JPH10319631A - Production of toner for developing electrostatic charge image - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a toner having a sharp particle size distribution and excellent in durability. SOLUTION: A process for preparing a polymerizable monomer compsn., a process for preparing a dispersive medium, a process for granulating toner particles and a polymerizing process are carried out. In the 2nd process, a dispersant is formed by mixing trisodium phosphate contg. 0.1-5.0% (expressed in terms of sodium hydroxide) free alkali with an aq. soln. of calcium chloride.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a method for producing a toner for visualizing an electrostatic latent image.

[0002]

2. Description of the Related Art Electrophotography is disclosed in U.S. Pat.
A number of methods are known as described in US Pat. No. 691, generally using a photoreceptor made of a photoconductive material, forming an electric latent image on the photoreceptor by various means, and then forming the latent image on the photoreceptor. The latent image is developed using a toner to form a visible image, and if necessary, a toner image is transferred to a transfer material such as paper.
The toner image is fixed on the transfer material by heat, pressure or the like to obtain a copy or printed matter. Various methods have been conventionally proposed as a method of developing with toner or a method of fixing a toner image.

Conventionally, toners used for these purposes are:
In general, a colorant comprising a dye or a pigment is melt-kneaded in a thermoplastic resin, uniformly dispersed, and then finely pulverized by a fine pulverizing device. Has been manufactured.

[0004] Although this method can produce fairly good toners, it has certain limitations, namely, the range of choice of toner materials. For example, the resin colorant dispersion must be brittle enough to be pulverized in economically feasible manufacturing equipment. However, when the resin colorant dispersion is fragile to satisfy these requirements, when the dispersion is actually finely pulverized at a high speed, the particle size range of the formed particles tends to be widened, and in particular, a relatively large proportion of fine particles Is included in this. Further, a toner obtained from such a brittle material is liable to be further pulverized or powdered in a developing device such as a copying machine. Also,
In this method, it is difficult to completely and uniformly disperse solid fine particles such as a colorant in a resin, and depending on the degree of the dispersion, an increase in fog during image formation, a decrease in image density, color mixing or transparency. Great care must be taken in dispersing the colorant as this will cause defects. Also, by exposing the colorant to the fracture surface of the pulverized particles,
In some cases, the development characteristics may fluctuate.

On the other hand, in order to overcome the problems of the toner caused by these pulverization methods, Japanese Patent Publication Nos.
Various polymerization toners and production methods thereof have been proposed, including the suspension polymerization toners disclosed in Japanese Patent Nos. 10799 and 51-14895 and the like. For example, in a suspension polymerization method toner, a polymerizable monomer, a colorant and a polymerization initiator, and if necessary, a crosslinking agent, a charge control agent, and other additives are uniformly dissolved or dispersed to prepare a monomer composition. And then
The monomer composition is dispersed in a continuous phase containing a dispersion stabilizer, for example, an aqueous phase using a suitable stirrer, and simultaneously undergoes a polymerization reaction to obtain toner particles having a desired particle size.

According to this method, since a pulverizing step is not included at all, the toner does not need to be brittle, a soft material can be used as a resin, and the colorant is not exposed on the particle surface. There is an advantage that a toner having a uniform triboelectric charging property can be obtained. Further, the particle size distribution of the obtained toner is relatively sharp. Further, since a large amount of a low softening point substance can be included in the toner as a release agent, there is an advantage that the obtained toner is excellent in offset resistance.

[0007]

As the dispersant used in the suspension polymerization method, for example, polyvinyl alcohol, gelatin, methylcellulose, methylhydroxypropylcellulose, ethylcellulose, sodium salt of carboxymethylcellulose, starch and the like can be used. Molecules have been proposed. However, when these dispersants are used, the resulting toner particles contain many fine particles, and
The result is a broad particle size distribution.

[0008] Further, as poorly water-soluble inorganic compounds, tricalcium phosphate, magnesium phosphate, aluminum phosphate, zinc phosphate, calcium carbonate, magnesium carbonate,
Calcium hydroxide, magnesium hydroxide, aluminum hydroxide, calcium metasilicate, calcium sulfate, barium sulfate, bentonite, silica, alumina and the like have been proposed. When these dispersants are used, toner particles having a relatively sharp particle size distribution can be obtained, but the stability of the particles during the polymerization reaction is slightly unstable, so that coalescence of the particles easily occurs, and coarse particles are generated. It's easy to do. As measures against these problems, JP-A-60-117256,
179650 proposes a method in which a dispersant is additionally added during polymerization or after granulation. Although these methods are certainly useful, they have the disadvantage of complicating the process and stabilizing the physical properties (such as molecular weight distribution) of the obtained toner due to temperature changes in the reaction system.

Further, the combination use of a poorly water-soluble inorganic compound and a surfactant is disclosed in JP-A-4-195153 and JP-A-6-124.
However, it is difficult to completely remove the surfactant after completion of the polymerization reaction, and it is difficult to stabilize the charging characteristics of the obtained toner.

Therefore, an object of the present invention is to reduce the generation of fine particles and coarse particles without going through complicated steps,
An object of the present invention is to provide a method for producing a toner having a high yield and a sharp particle size distribution.

Another object of the present invention is to provide a method for producing a toner having excellent chargeability.

Another object of the present invention is to provide a method for producing a toner having excellent fixability.

[0013]

The object of the present invention is to provide a method for producing a toner comprising a polymerizable monomer composition preparing step, a dispersion medium preparing step, a toner particle granulating step and a polymerization step. The step is achieved by mixing trisodium phosphate containing 0.1 to 5.0% of a free alkali as sodium hydroxide with an aqueous solution of calcium chloride to generate a dispersant.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.

As a result of intensive studies, the present inventors have mixed trisodium phosphate containing 0.1 to 5.0% of free alkali as sodium hydroxide with an aqueous solution of calcium chloride to precipitate hydroxyapatite. By granulating the polymerizable monomer composition in a dispersion medium, the generation of fine particles and coarse particles is reduced without complicated steps, and a toner with a sharp particle size distribution can be obtained in high yield. I found something to be done.

This is because when hydroxyapatite is produced,
It is considered that the presence of excess free alkali generates extremely fine and uniform hydroxyapatite, which can be stably present.

When the content of the free alkali exceeds 5.0%, the pH in the reaction system becomes too high, and the hydrolysis of the ester in the polymerizable monomer composition is not preferred. On the other hand, if it is less than 0.1%, it is insufficient to produce fine and uniform hydroxyapatite.

The hydroxyapatite is preferably prepared so as to be 0.2 to 10.0% based on the polymerizable monomer composition. When the content is less than 0.2%, the amount of coarse particles is large. On the contrary, when the content is more than 10.0%, a large amount of fine particles are generated, and a desired particle size distribution cannot be obtained.

In the step of preparing a dispersion medium, the liquid temperature is preferably 40 ° C. or higher. When the liquid temperature is lower than 40 ° C., fine and uniform hydroxyapatite is not formed.

Further, it is preferable that the dispersant is generated by a stirring means having a high shearing force. This is because a very fine and uniform dispersant can be obtained when the dispersant is formed under a high shear force. As a device for granulating by high shearing force used in the present invention, T.I. K. Homomixer,
T. K. Any of high-line mills (manufactured by Tokushu Kika Kogyo Co., Ltd.) and Clear Mix (M-Technic Co., Ltd.) may be used as long as they impart a high shearing force.

In the method for producing a toner according to the present invention, the polymerizable monomer composition preferably contains a polar resin. This is because the polar resin is localized at the particle interface, electrically acts with the dispersant, and further stabilizes the particles during granulation / polymerization. As the polar resin used in the present invention,
Styrene and (meth) acrylic acid copolymers, maleic acid copolymers, saturated polyester resins and epoxy resins are preferably used. It is particularly preferable that the polar resin does not contain an unsaturated group capable of reacting with the polymerizable monomer in the molecule.

The molecular weight of the polar resin is Mw of 5,
000-50,000, Mw / Mn 1.2-5.
0 is preferred. If the Mw is smaller than 5,000, the resulting toner will have reduced blocking resistance. Also, 50,
If it exceeds 000, the toner will have poor low-temperature fixability. The glass transition temperature (Tg) is preferably set higher than the Tg of the outer shell resin.

The toner of the present invention preferably has a core / shell structure.

As a specific method for encapsulating the low softening point substance, the polarity of the material in the aqueous medium is set to be smaller for the low softening point substance than for the main monomer, and a small amount of a large polar resin or By adding a monomer, a toner having a so-called core / shell structure in which a material having a low softening point is coated with an outer shell resin can be obtained.

The main component of the core is a low softening point substance, and the low softening point substance preferably has a melting point of 40 to 90 ° C. The melting point is measured according to ASTM D3418-
8 was determined as the main peak value measured. If the maximum peak is less than 40 ° C., the self-cohesive force of the low softening point substance becomes weak, and as a result, the high-temperature offset property becomes weak, which is not preferable. On the other hand, when the maximum peak exceeds 90 ° C., the fixing temperature increases, which is not preferable. Furthermore, if the temperature of the maximum peak value is high, a substance having a low softening point mainly precipitates during granulation, which is not preferable because it hinders the suspension system.

In the measurement of the temperature of the maximum peak value of the present invention,
For example, DSC-7 manufactured by PerkinElmer is used. The temperature correction of the device detection unit uses the melting points of indium and zinc, and the heat quantity correction uses the heat of fusion of indium. An aluminum pan was used as a sample, an empty pan was set as a control, and the temperature was raised at a rate of 10 ° C./min. Was measured.

Specifically, paraffin wax, polyolefin wax, Fischer-Tropsch wax,
Amide waxes, higher fatty acids, ester waxes and their derivatives or their graft / block compounds can be used.

The low softening point substance is added to the toner in an amount of 5 to 30%.
It is preferable to add by weight. If the addition is less than 5% by weight, sufficient fixability cannot be obtained, and if the addition exceeds 30% by weight, coalescence of toner particles tends to occur during granulation even in production by a polymerization method, and the particle size distribution is poor. A wide product was easily formed and was not suitable for the present invention.

As a specific method for measuring the tomographic plane of the toner in the present invention, the toner is sufficiently dispersed in a room temperature curable epoxy resin and then cured in an atmosphere at a temperature of 40 ° C. for 2 days. After dyeing the cured product using ruthenium tetroxide, osmium tetroxide as needed,
A flaky sample was cut out using a microtome provided with diamond teeth, and the tomographic morphology of the toner was measured using a transmission electron microscope (TEM). In the present invention, it is preferable to use a ruthenium tetroxide staining method in order to give a contrast between the materials by utilizing a slight difference in crystallinity between the low softening point substance used and the resin constituting the outer shell. .

The polymerizable monomer used in the present invention includes styrene, o (m-, p-)-methylstyrene, m
Styrene monomers such as (p-)-ethylstyrene; methyl (meth) acrylate, ethyl (meth) acrylate,
Propyl (meth) acrylate, butyl (meth) acrylate, octyl (meth) acrylate, dodecyl (meth) acrylate, stearyl (meth) acrylate, behenyl (meth) acrylate, 2-ethylhexyl (meth) acrylate (Meth) acrylate monomers such as dimethylaminoethyl (meth) acrylate and diethylaminoethyl (meth) acrylate; ene monomers such as butadiene, isoprene, cyclohexene, (meth) acrylonitrile, and acrylamide The body is preferably used. These can be used alone or in general in the published Polymer Handbook, 2nd Edition (J) -P139-192 (John Wiley).
& Sons Corporation) theoretical glass transition temperature (Tg)
However, monomers are appropriately mixed and used so as to show a temperature of 40 to 80 ° C. If the theoretical glass transition temperature is less than 40 ° C,
Problems arise in terms of the storage stability of the toner and the durability stability of the developer. On the other hand, when the temperature exceeds 80 ° C., the fixing point is increased. In particular, in the case of a full color toner, the color mixture of each color toner becomes insufficient. Poor color reproduction and OHP
The transparency of the image is remarkably reduced, which is not preferable from the viewpoint of high image quality.

The molecular weight of the shell resin is measured by GPC (gel permeation chromatography). As a specific measuring method of GPC, a toner is extracted in advance with a toluene solvent using a Soxhlet extractor for 20 hours, and then toluene is distilled off with a rotary evaporator. An organic solvent in which the resin cannot be dissolved, for example, chloroform, etc., was added and washed sufficiently, and a solution obtained by dissolving a solution in THF (tetrahydrofuran) was filtered through a solvent-resistant membrane filter having a pore diameter of 0.3 μm. 150C
And the column configuration was A-801, 802, manufactured by Showa Denko
803, 804, 805, 806, 807 can be connected to measure the molecular weight distribution using a standard polystyrene resin calibration curve. The number average molecular weight (Mn) of the obtained resin component is 5,
000 to 1,000,000, and the ratio (Mw / Mn) between the weight average molecular weight (Mw) and the number average molecular weight (Mn)
In the present invention, an outer shell resin showing 2 to 100 is preferable.

In the present invention, an outermost shell resin layer may be further provided on the surface of the toner.

The glass transition temperature of the outermost resin layer is designed to be equal to or higher than the glass transition temperature of the outer resin layer in order to further improve the blocking resistance, and is further crosslinked so as not to impair fixability. Is preferred. The outermost resin layer preferably contains a polar resin and a charge control agent for improving the chargeability.

The method for providing the outermost shell resin layer is not particularly limited, but includes, for example, the following methods.

1. The latter half of the polymerization reaction, or after the end, if necessary in the reaction system, dissolved polar resin, charge control agent, cross-linking agent, etc., added a monomer dispersed and adsorbed on the polymer particles,
A method in which polymerization is performed by adding a polymerization initiator.

2. If necessary, an emulsion polymerization particle or a soap-free polymerization particle composed of a monomer containing a polar resin, a charge control agent, a cross-linking agent, etc. is added to the reaction system, and aggregated on the surface of the polymerization particle.If necessary, heat or the like is used. How to stick.

3. A method in which emulsion polymerized particles or soap-free polymerized particles comprising a monomer containing a polar resin, a charge control agent, a cross-linking agent, and the like, if necessary, are dry-mechanically fixed to the toner particle surfaces.

As the colorant used in the present invention, a black colorant which is toned to black using carbon black, a magnetic substance, and a yellow / magenta / cyan colorant shown below is used.

Examples of the yellow colorant include condensed azo compounds, isoindolinone compounds, anthraquinone compounds,
Compounds represented by azo metal complexes, methine compounds and allylamide compounds are used. Specifically, C.I. I. Pigment Yellow 12, 13, 14, 15, 17, 6
2, 74, 83, 93, 94, 95, 109, 110,
111, 128, 129, 147, 168, etc. are preferably used.

Examples of the magenta colorant include condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinones, quinacridone compounds, basic dye lake compounds, naphthol compounds, benzimidazolone compounds, thioindigo compounds, and perylene compounds. Specifically, C.I.
I. Pigment Red 2, 3, 5, 6, 7, 23, 4
8; 2, 48; 3, 48; 4, 57; 1, 81; 1, 1
44, 146, 166, 169, 177, 184, 18
5, 202, 206, 220, 221, 254 are particularly preferred.

As the cyan coloring agent, copper phthalocyanine compounds and derivatives thereof, anthraquinone compounds, basic dye lake compounds and the like can be used. Specifically, C.I. I.
Pigment Blue 1, 7, 15, 15: 1, 15: 2,
15; 3, 15: 4, 60, 62, 66 and the like can be particularly preferably used. These colorants can be used alone or as a mixture or in the form of a solid solution. In the case of a color toner, the colorant of the present invention is selected from the viewpoints of hue angle, saturation, lightness, weather resistance, OHP transparency, and dispersibility in the toner. The amount of the coloring agent is 1 to 100 parts by weight of the resin.
Used in an amount of up to 20 parts by weight.

When a magnetic material is used as the black colorant, unlike other colorants, 40 to 100 parts by weight of the resin is used.
Used by adding 150 parts by weight.

The charge control agents used in the present invention include:
Although a known toner can be used, in the case of a color toner, a charge control agent which is colorless, has a high toner charging speed, and can stably maintain a constant charge amount is particularly preferable. Furthermore,
A charge control agent having no polymerization inhibition and no solubilized substance in an aqueous system is particularly preferable. Specific compounds include salicylic acid, naphthoic acid, metal compounds of dicarboxylic acids, sulfonic acids, high molecular compounds having carboxylic acids in their side chains, boron compounds, urea compounds, silicon compounds, curryx arenes, etc. as negative compounds. As the positive system, a quaternary ammonium salt, a high molecular compound having the quaternary ammonium salt in a side chain, a guanidine compound, an imidazole compound and the like are preferably used. The charge control agent is preferably used in an amount of 0.5 to 10 parts by weight based on 100 parts by weight of the resin. However, in the present invention, the addition of a charge control agent is not essential, and when a two-component developing method is used, a non-magnetic one-component blade coating developing method utilizing frictional charging with a carrier is used. In this case, the toner does not always need to include a charge control agent by positively utilizing the triboelectric charging between the blade member and the sleeve member.

Examples of the polymerization initiator used in the present invention include 2,2′-azobis- (2,4-dimethylvaleronitrile), 2,2′-azobisisobutyronitrile,
1,1′-azobis (cyclohexane-1-carbonitrile), 2,2′-azobis-4-methoxy-2,4-
Azo-based polymerization initiators such as dimethylvaleronitrile and azobisisobutyronitrile, benzoyl peroxide, methyl ethyl ketone peroxide, diisopropyl peroxycarbonate, cumene hydroperoxide, 2,4-
A peroxide-based polymerization initiator such as dichlorobenzoyl peroxide and lauroyl peroxide is used.

The amount of the polymerization initiator to be added varies depending on the desired degree of polymerization, but generally ranges from 0.5 to 2 parts by weight based on the monomer.
0% by weight is used. The type of the initiator slightly varies depending on the polymerization method, but with reference to the 10-hour half-life temperature,
Used alone or as a mixture.

In order to control the degree of polymerization, a known crosslinking agent, chain transfer agent, polymerization inhibitor or the like may be further added and used.

The step of preparing a dispersion medium according to the present invention is specifically performed as follows.

Trisodium phosphate containing 0.1 to 5.0% of a free alkali as sodium hydroxide and calcium chloride are mixed with each other in an aqueous solution so as to be equivalent based on the following chemical reaction formula for hydroxyapatite formation. Is prepared, and an aqueous calcium chloride solution is added to an aqueous solution of trisodium phosphate at 40 ° C. or higher under high shearing force to generate hydroxyapatite. _{10CaCl 2 · 2H 2 O + 6Na} 3 PO 4 + 2H 2 O
→ [Ca ₃ (PO ₄ ) ₂ ] ₃・ Ca (OH) ₂ ↓ + 18
NaCl + 2HCl

A specific method for producing a toner according to the present invention is to add a releasing agent, a colorant, a charge control agent, a polymerization initiator and other additives which are low softening points to a polymerizable monomer. The polymerizable monomer composition uniformly dissolved or dispersed by an ultrasonic disperser or the like is dispersed in the dispersion medium prepared in the above-described dispersion medium preparation step using a homomixer or the like.

The granulation step is stopped when the desired size of the toner particles is obtained from the droplets of the polymerizable monomer composition.

Thereafter, the polymerization temperature is kept at 40 ° C. or higher, generally 50 to 9 while stirring to such an extent that the particle state is maintained and the sedimentation of the particles is prevented by the action of the dispersant.
The polymerization step is performed at a temperature of 0 ° C.

The temperature may be raised in the latter half of the polymerization reaction, and the above-described method of providing the outermost shell layer may be performed.

Further, in order to remove unreacted polymerizable monomers and by-products, the aqueous medium may be partially distilled off in the latter half of the reaction or after completion of the reaction.

After the completion of the reaction, the suspension is made acidic, the hydroxyapatite is dissolved, and the resulting toner particles are washed.
Collect by filtration and dry.

In the suspension polymerization method, it is usually preferable to use 300 to 3000 parts by weight of water as a dispersion medium with respect to 100 parts by weight of the polymerizable monomer composition.

The external additive used for the purpose of imparting various toner properties preferably has a particle diameter of 1/10 or less of the weight average diameter of the toner particles from the viewpoint of durability when added to the toner. . The particle size of the additive means an average particle size obtained by observing the surface of the toner particles with an electron microscope. As the external additive, for example, the following are used.

Metal oxides (aluminum oxide, titanium oxide, strontium titanate, cerium oxide, magnesium oxide, chromium oxide, tin oxide, zinc oxide, etc.), nitrides (silicon nitride, etc.), carbides (silicon carbide, etc.)
Metal salts (calcium sulfate, barium sulfate, calcium carbonate, etc.), fatty acid metal salts (zinc stearate, calcium stearate, etc.), carbon black, silica, etc.

These external additives are used in an amount of 0.01 to 10 parts by weight, preferably 0.05 to 5 parts by weight, based on 100 parts by weight of the toner particles. These external additives may be used alone or in combination. Those subjected to a hydrophobic treatment are more preferable.

The average particle size and particle size distribution of the toner can be measured by various methods such as Coulter Counter TA-II or Coulter Multisizer (manufactured by Coulter Co., Ltd.). In the present invention, the Coulter Counter TA-I is used.
Interface (Nikkaki) and PC980 for outputting number distribution and volume distribution using Type I (Coulter)
1 A personal computer (manufactured by NEC) is connected, and a 1% NaCl aqueous solution is prepared using primary grade sodium chloride as an electrolytic solution. For example, ISOTON R-II (manufactured by Coulter Scientific Japan) can be used. As a measuring method, 100 to 150 m of the electrolytic aqueous solution is used.
A surfactant, preferably an alkylbenzene sulfonate, is added as a dispersant in an amount of 0.1 to 5 ml, and a measurement sample is further added in an amount of 2 to 20 mg. The electrolytic solution in which the sample was suspended was subjected to dispersion treatment for about 1 to 3 minutes using an ultrasonic disperser, and the volume and number of toner particles of 2 μm or more were measured using a 100 μm aperture as the aperture by the Coulter Counter TA-II. The volume distribution and number distribution were calculated. Then, a volume-based weight average particle diameter (D4: the median value of each channel is a representative value of the channel) and a weight variation coefficient (S
4), the number-based length average particle diameter (D
1) and the length variation coefficient (S1) were determined.

The image density is a value obtained by measuring (5 mm square, 5 mm round, solid black) with a Macbeth densitometer (manufactured by Macbeth).

Hereinafter, the present invention will be described in more detail with reference to specific production methods, examples and comparative examples.

[0062]

【Example】

[Example 1] Prepared using trisodium phosphate containing 1.4% of free alkali as sodium hydroxide,
600 ml of a 0.1 M Na ₃ PO _{4 4} aqueous solution was poured into 500 ml of ion-exchanged water, heated to 60 ° C., and TK
Using a homomixer (manufactured by Tokushu Kika Kogyo)
The mixture was stirred at 00 rpm. 1.0M-CaCl ₂
100 ml of an aqueous solution was gradually added to obtain an aqueous medium containing hydroxyapatite. On the other hand, (monomer) 170 g of styrene 30 g of n-butyl acrylate (colorant) I. Pigment Blue 15.3 10 g (Charge control agent) Salicylic acid metal compound 1 g (Polar resin) Saturated polyester 20 g (Acid value 10, peak molecular weight; 11,000) (Release agent) Ester wax (melting point 70 ° C.) 40 g

The above formulation was heated to 60 ° C. and 10,000 rpm using a TK homomixer (manufactured by Tokushu Kika Kogyo).
m and uniformly dispersed. In addition, polymerization initiator 2,
2'-azobis (2,4-dimethylvaleronitrile) 5
g was dissolved to prepare a polymerizable monomer composition.

The polymerizable monomer composition was charged into the aqueous medium, and the mixture was stirred at 60 ° C. under a nitrogen atmosphere with a TK homomixer at 10,000 rpm for 15 minutes.
The polymerizable monomer composition was granulated. Thereafter, the temperature was raised to 70 ° C. while stirring with a paddle stirring blade, and the reaction was performed for 10 hours.
After completion of the polymerization reaction, the remaining monomer was distilled off under reduced pressure, and after cooling, hydrochloric acid was added to dissolve the hydroxyapatite,
After filtration, washing and drying, colored suspension particles were obtained. Hydrophobic silica having a specific surface area of 200 m ² / g by a BET method was externally added to 100 parts by weight of the obtained particles to obtain a polymerized toner. Table 1 summarizes the physical properties of the obtained toner.

When the tomographic plane of the toner was observed, a core / shell structure was confirmed.

Example 2 A similar operation was performed as in Example 1 except that trisodium phosphate containing 2.1% of free alkali as sodium hydroxide was used, and a quinacridone pigment was used as a coloring agent. Thus, a polymerized toner was obtained. Table 1 summarizes the physical properties of the obtained toner.

When the tomographic plane of the toner was observed, a core / shell structure was confirmed.

[Example 3] In Example 1, trisodium phosphate containing 0.5% of free alkali as sodium hydroxide was used, and C.I. I. Pigment Yellow 17 was used, and the same operation was performed to obtain a polymerized toner. Table 1 summarizes the physical properties of the obtained toner.

When the tomographic plane of the toner was observed, a core / shell structure was confirmed.

Example 4 A polymerized toner was obtained in the same manner as in Example 1, except that the liquid temperature in the dispersion medium preparation step was 30 ° C., and then the temperature was raised to 60 ° C. Table 1 summarizes the physical properties of the obtained toner.

When the tomographic plane of the toner was observed, a core / shell structure was confirmed.

To 5 parts by weight of this toner, 95 parts by weight of an acryl-coated ferrite carrier were mixed to prepare a developer. Using this developer, continuous printing of 5,000 single-color images was evaluated using a modified full-color copying machine CLC500 manufactured by Canon Inc., and fogging occurred around 4,500 sheets.

Example 5 A developer was prepared by mixing 95 parts by weight of an acryl-coated ferrite carrier with 5 parts by weight of the toner obtained in Examples 1 to 3. Using this developer, a Canon full color copier CLC500
Evaluation of image output on 5,000 continuous sheets was performed using a remodeled machine. As a result, no fog was found, the image density was stable, and good images were obtained.

[Comparative Example 1] A similar operation was performed as in Example 1 except that trisodium phosphate containing 0.05% of free alkali as sodium hydroxide was used.
A polymerized toner was obtained. Table 1 summarizes the physical properties of the obtained toner.

When the tomographic surface of the toner was observed, a core / shell structure was confirmed.

To 5 parts by weight of this toner, 95 parts by weight of an acryl-coated ferrite carrier were mixed to prepare a developer. When this developer was used to evaluate 5,000 continuous single-color images on a modified full-color copying machine CLC500 manufactured by Canon Inc., fogging occurred at around 4,000 sheets.

Comparative Example 2 A polymerized toner was obtained in the same manner as in Example 1, except that trisodium phosphate containing 5.5% of free alkali as sodium hydroxide was used. Table 1 summarizes the physical properties of the obtained toner.

When the tomographic plane of the toner was observed, a core / shell structure was confirmed.

To 5 parts by weight of the toner, 95 parts by weight of an acryl-coated ferrite carrier were mixed to prepare a developer. Using this developer, continuous printing of 5,000 single-color images was evaluated using a modified full-color copying machine CLC500 manufactured by Canon Inc., and fogging occurred at about 1,000 sheets.

[0080]

[Table 1]

[0081]

As described above, according to the present invention, a very fine and uniform dispersant can be obtained, and as a result, a toner having a sharp particle size distribution and excellent durability can be obtained.

Claims (8)

[Claims] 1. A method for producing a toner comprising a step of preparing a polymerizable monomer composition, a step of preparing a dispersion medium, a step of granulating toner particles, and a step of polymerization. A method for producing a toner for developing an electrostatic image, comprising mixing an aqueous solution of calcium chloride with trisodium phosphate containing 0.1 to 5.0% as sodium to form a dispersant. 2. The method according to claim 1, wherein the dispersant is hydroxyapatite. 3. The method for producing a toner for developing an electrostatic charge image according to claim 1, wherein the liquid temperature in the dispersion medium preparation step is 40 ° C. or higher. 4. The method according to claim 1, wherein the dispersant is generated by a stirring means having a high shearing force. 5. The electrostatic image according to claim 1, wherein the dispersant is prepared to be 0.2 to 10.0% based on the polymerizable monomer composition. A method for producing a developing toner. 6. The method for producing a toner for developing an electrostatic image according to claim 1, wherein a polar resin is contained in the polymerizable monomer composition. 7. The method for producing an electrostatic image developing toner according to claim 1, wherein the toner has a core / shell structure. 8. The toner according to claim 7, wherein a main component of the core is a low softening point substance, and the melting point of the low softening point substance is 40 to 90 ° C. Production method.