JP2922616B2 - Electrophotographic toner and method for producing the same - Google Patents

Description

The present invention relates to an electrophotographic toner and a method for producing the same.
More specifically, the present invention relates to an electrophotographic toner used for an electrostatic copying machine, a laser beam printer, and the like, and a method for manufacturing the same.

<Prior Art and Problems to be Solved by the Invention> Conventionally, for the purpose of improving charging characteristics, improving image quality, and the like, an electrophotographic toner containing a charge control agent or an electrophotographic toner having a surface treated with the charge control agent has been used. Various photographic toners have been proposed.

As an electrophotographic toner containing a charge control agent,
For example, the following are mentioned.

An electrophotographic toner containing a salt of an aliphatic quaternary ammonium and tetraphenylboron for imparting chargeability (see JP-A-59-78364).

An electrophotographic toner containing a salt of a tertiary amine and sulfonic acid for imparting chargeability and preventing deterioration of the fixing roller (see JP-A-59-119363).

An electrophotographic toner containing a salt of a long-chain aliphatic quaternary ammonium and a long-chain carboxylic acid in order to make the charging characteristics uniform (see JP-A-63-23167).

An electrophotographic toner containing a salt of an aliphatic quaternary ammonium and molybdic acid or tungstic acid in order to improve charge stability (see JP-A-64-54).

An electrophotographic toner containing a water-soluble dye for imparting chargeability (see JP-A-64-90454).

Electrophotographic toner containing nigrosine and an aliphatic quaternary ammonium salt to improve image quality
-259371).

In addition, as an electrophotographic toner whose surface is treated with a charge controlling agent, for example, in order to facilitate charge injection and improve developability,
An electrophotographic toner in which an anionic surfactant is adsorbed on the surface (see JP-A-59-135480).

However, in the above-described electrophotographic toners, the charge control agent is simply mixed in the fixing resin, and thus, the toner in the toner is subjected to a shearing force due to friction between the toner and the carrier during repeated image formation. There is a problem that the charge control agent separates from the toner and moves to the carrier, thereby deteriorating the chargeability of the developer.

Further, in the electrophotographic toner, since the styrene-acrylic resin used as the fixing resin is negatively charged in water, the anionic surfactant has resin particles on the alkyl group side which is a lipophilic group. Adsorb to. For this reason, the resulting electrophotographic toner becomes hydrophilic due to the hydrophilic group of the anionic surfactant, and thus has a problem that the environmental charging stability under high temperature and high humidity is reduced.

An electrophotographic toner in which a carboxyl group on the surface of a toner is treated with a divalent or higher valent metal cation is also known (see JP-A-58-211164). This is intended to enhance the offset resistance of the toner by crosslinking the fixing resin of the toner with a metal cation, but does not contribute to the improvement of the charging characteristics. Conversely, the salt between the carboxyl group and the metal cation is used. Is inferior in water resistance, so that there is a problem that environmental charging stability is deteriorated.

The present invention has been made in view of the above circumstances, and does not cause the charge control agent to transfer from the toner to the carrier during repeated image formation, and has excellent environmental charge stability. It is an object of the present invention to provide a toner for use and an efficient production method thereof.

<Means and Actions for Solving the Problems> To solve the above problems, the electrophotographic toner of the present invention is obtained by subjecting a monomer to suspension polymerization in water in which an alkali metal salt of a polycarboxylic acid is dissolved. A particulate toner having a carboxylate group on the surface, wherein a charge control agent is formed on the surface by adsorption of a cationic surfactant on the surface.

Further, the method for producing an electrophotographic toner of the present invention, after hardly water-soluble or insoluble monomer is subjected to suspension polymerization in water in which an alkali metal salt of polycarboxylic acid is dissolved, to obtain resin particles, It is characterized in that the resin particles are treated with a cationic surfactant.

In the present invention having the above-described structure, the carboxylate group unevenly distributed on the surface of the resin particles, which is caused by the alkali metal salt of polycarboxylic acid grafted and incorporated into the surface of the resin particles during the suspension polymerization, is used. Since the charge control agent is formed on the surface by adsorbing the cationic surfactant, the charge control agent is strongly bonded to the toner surface, and is separated from the toner and transferred to the carrier during repeated image formation. Less to do. In addition, since the surfactant forming the charge control agent is cationic, there is no possibility of causing a decrease in chargeability of the carrier even if the surfactant is transferred to the carrier. Moreover, since the cationic surfactant is adsorbed to the negatively charged resin particles in water on the hydrophilic group side, the obtained electrophotographic toner is
Due to the hydrophobic group of the cationic surfactant, the cationic surfactant becomes hydrophobic, and environmental charge stability is improved.

The monomer used in the present invention is an ethylenically unsaturated monomer that has radical polymerizability and is hardly soluble or insoluble in water, and suitable examples thereof include a monovinyl aromatic monomer and an acrylic monomer. Monomers, vinyl ester monomers, vinyl ether monomers, diolefin monomers, monoolefin monomers, halogenated olefin monomers, polyvinyl monomers and the like.

As the monovinyl aromatic monomer, the following general formula (I), Monovinyl aromatic hydrocarbons represented by, for example, styrene, α-methylstyrene, vinyltoluene, α-chlorostyrene, o, m, p-chlorostyrene, p-ethylstyrene, sodium styrenesulfonate, divinylbenzene .

As the acrylic monomer represented by the following general formula (II), For example, methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, phenyl acrylate, methyl methacrylate, butyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, β- Ethyl hydroxyacrylate, butyl γ-hydroxyacrylate, butyl δ-hydroxyacrylate, ethyl β-hydroxymethacrylate, propyl γ-aminoacrylate,
γ-N, N-diethylamino propyl acrylate, ethylene glycol dimethacrylate, and tetraethylene glycol dimethacrylate. Since acrylic acid and methacrylic acid are easily soluble in water,
It cannot be used in the present invention.

Examples of the vinyl ester monomer represented by the following general formula [III] include vinyl formate, vinyl acetate, and vinyl propionate.

Examples of the vinyl ether monomer represented by the following general formula [IV] include vinyl methyl ether, vinyl ethyl ether, vinyl-n-butyl ether, vinyl phenyl ether, and vinyl cyclohexyl ether.

Examples of the diolefin-based monomer represented by the following general formula [V] include butadiene, isoprene and chloroprene.

Monoolefin monomers represented by the following set [VI] include, for example, ethylene, propylene, butene-1,
Penten-1 and 4-methylpentene-1 are exemplified.

Examples of the halogenated olefin-based monomer include vinyl chloride and vinylidene chloride, and examples of the polyvinyl-based monomer include divinylbenzene, diallyl phthalate, and tricyanurate.

Each of the above monomers can be used alone or in combination of two or more. Among the above-mentioned monomers, the monomers suitably used in the present invention include styrene, (meth) acrylate, a combination system of styrene and (meth) acrylate, and a mixture of styrene and divinylbenzene. Combination systems are mentioned.

Examples of the alkali metal salt of polycarboxylic acid, which is dissolved in water for suspension polymerization of the monomer, include a polymer of an alkali metal (meth) acrylate or an alkali metal (meth) acrylate. And other monomers such as styrene and (meth) acrylate are preferably used. The amount of the alkali metal salt of the polycarboxylic acid is preferably in the range of 0.1 to 10 parts by weight per 100 parts by weight of the monomer. The amount of water used is preferably in the range of 100 to 500 parts by weight per 100 parts by weight of the monomer.

A polymerization initiator or the like for initiating polymerization of the monomer is blended in the reaction solution in which the above components are dispersed.

As the polymerization initiator, azo compounds such as azobisisobutyronitrile; cumene hydroperoxide, t-butyl hydroperoxide, dicumyl peroxide, di-t-
Conventionally known radical polymerization initiators such as butyl peroxide, benzoyl peroxide, and peroxides such as lauroyl peroxide can be used, and when performing polymerization by irradiation of ultraviolet light or visible light, a conventionally known photopolymerization initiator can be used. Can also be used. As the polymerization initiator, those which are insoluble in water and soluble in monomers are used. The amount of the polymerization initiator to be used is preferably in the range of 0.001 to 10% by weight, particularly 0.01 to 0.5% by weight, based on the monomer. When the polymerization is started using γ rays, accelerated electron beams, or the like, the above polymerization initiator may not be used.

Further, in addition to the above-mentioned components, for example, a charge control agent known per se, an offset preventing agent (release agent), and the like can be added to the reaction solution, if necessary.

The charge control agent is compounded when the toner is used in a two-component developer, and includes a nigrosine base (CI5045),
Oil-soluble dyes such as oil black (CI26150) and spiron black; metal naphthenate, fatty metal soap, resin acid soap and the like.

Examples of the anti-offset agent include low molecular weight polyethylene, low molecular weight polypropylene, various waxes, and silicone oil.

The reaction solution containing each of the above components is stirred using a homomixer, a homogenizer, or the like, and the polymerization reaction is performed in a state where the monomers are dispersed in water as oil droplet particles having a uniform particle size distribution suitable for the toner. I do. At this time, it is preferable to replace the inside of the reaction system with an inert gas in order to suppress the termination reaction of the polymerization due to oxygen. As the polymerization reaction proceeds, resin particles having the alkali metal salt of polycarboxylic acid grafted and incorporated on the particle surface are obtained. After completion of the reaction, the resin particles are separated from the reaction solution by filtration, and, if necessary, are subjected to an acid treatment using dilute hydrochloric acid or the like, and then washed with water or a suitable solvent and dried to cause the alkali metal salt of polycarboxylic acid. Carboxylate groups are unevenly distributed on the surface. The acid treatment is not necessarily required in the present invention, but it is preferable to perform the acid treatment in order to increase the ζ potential of the resin particles in water and to promote the adsorption of the cationic surfactant. . The particle size of the resin particles obtained as described above is not particularly limited, but is preferably in the range of 1 to 30 μm.

In order to color the resin particles, a colorant such as a pigment or a dye is dispersed in the reaction solution, and with the polymerization of the monomer, the colorant is incorporated into the resin particles and colored.
There is a method of dyeing the resin particles after polymerization with a dye.

Examples of the pigment among the coloring agents used in the former method include various coloring pigments, extender pigments, conductive pigments, magnetic pigments, and photoconductive pigments. These may be used alone or in combination of two or more depending on the application.

As the coloring pigment, those described below are preferably used.

Black Carbon black such as furnace black, channel black, thermal, gas black, oil black, acetylene black, lamp black, aniline black.

White zinc white, titanium oxide, antimony white, zinc sulfide.

Red Bengala, Cadmium Red, Lead Tan, Mercury Sulfide, Permanent Red 4R, Risor Red, Pyrazolone Red, Watching Red Calcium Salt, Lake Red D, Brilliant Carmine 6B, Eosin Lake, Rhodamine Lake B, Alizarin Lake, Brilliant Carmine 3B.

Orange Red mouth yellow lead, molybdenum orange, permanent orange GTR, pyrazolo orange, Vulcan orange, indanthrene brilliant orange RK, benzidine orange G, indanthrene brilliant orange GK.

Yellow Yellow lead, zinc white, cadmium yellow, yellow iron oxide, mineral fast yellow, nickel titanium yellow, navels yellow, naphthol yellow S, Hanser yellow G, Hanser yellow 10G, benzidine yellow G, benzidine yellow GR, quinoline Yellow rake,
Permanent yellow NCG, tartrazine rake.

Green Chrome Green, Chrome Oxide, Pigment Green B, Malachite Green Lake, Fanal Yellow Green G.

Blue Navy Blue, Cobalt Blue, Alkaline Blue Lake, Victoria Blue Lake, Phthalocyanine Blue Partially Chlorinated, First Sky Blue, Indanthrene Blue B
C.

Purple Manganese purple, first violet B, methyl violet lake.

Examples of the extender include pearlite powder, barium carbonate, clay, silica, white carbon, talc, alumina white and the like.

Examples of the conductive pigment include conductive carbon black and aluminum powder.

Examples of magnetic pigments include various ferrites, for example, iron tetroxide (Fe ₃ O ₄ ), iron sesquioxide (γ-Fe ₂ O ₃ ), zinc iron oxide (ZnFe ₂ O ₄ ), and yttrium iron oxide (Y ₃ Fe ₅ O ₁₂ ), iron cadmium oxide (CdFe ₂ O ₄ ), iron gadolinium oxide (Gd ₃ Fe ₅ O ₄ ), iron oxide copper (CuFe ₂ O ₄ ), lead iron oxide (PbFe ₁₂ O ₁₉ ), and neodymium iron oxide (NdFeO ₃ ), barium iron oxide (BaFe ₁₂ O ₁₉ ), magnesium iron oxide (MgFe ₂ O ₄ ), iron manganese oxide (MnFe ₂ O ₄ ), lanthanum iron oxide (LaFeO ₃ ), iron powder, cobalt powder, nickel And the like.

Examples of the photoconductive pigment include zinc oxide, selenium, cadmium sulfide, cadmium selenide, and the like.

The pigment is used in a proportion of 1 to 20 parts by weight, preferably 2 to 10 parts by weight, based on 100 parts by weight of the monomer.

On the other hand, as the dye used in the former method, a dye that is more soluble in a monomer than water, for example, an oil-soluble dye is preferably used. Specific examples of the above oil-soluble dyes are shown below.

Black dye Black FS-Special A, Black S, Black #
103, Black # 107, Black # 215, Black # 141
(Both are brand names manufactured by Chuo Gosei Kagaku Co., Ltd.), Oplus (OPLA
S) Black HZ, Oplus Black # 836, Oplus Black # 838 (all are trade names manufactured by Orient Chemical Industries).

Red dye MACROLEX Red 5B, Macrorex Red Violet R (all trade names manufactured by Bayer AG), Samiplast Red AS, Samiplast Red B-2, Samiplast Red HLG-Z (all are Sumitomo) Opras Red RR, Opras Red # 330 (all trade names manufactured by Orient Chemical Industries), Red 6B, Red TR-71 (all trade names manufactured by Chuo Gosei Kagaku Co., Ltd.).

Orange dye Macrolex Orange 3G, Macrolex Orange R (all trade names made by Bayer), Orange S, Orange R, Orange # 826N (all trade names made by Chuo Gosei Kagaku), Oplus Orange PS, o Plus Orange RR (all trade names made by Orient Chemical Industries), Samiplast Orange HRP (trade names made by Sumitomo Chemical Co., Ltd.).

Yellow dye Macrolex Yellow 6G, Macrolex Yellow R (all trade names made by Bayer), Yellow D, Yellow GE, Yellow # 189 (all trade names made by Chuo Gosei Kagaku), Samiplast Yellow GC, Sami Plast Yellow R (all trade names manufactured by Sumitomo Chemical Co., Ltd.), Oplus Yellow 3G, Oplus Yellow # 130 (all trade names manufactured by Orient Chemical Co., Ltd.).

Violet dye Macrolex Violet 3R, Macrolex Violet B (all trade names made by Bayer), Violet MVB (trade name made by Chuo Gosei Kagaku), Samiplast Violet RR, Samiplast Violet B (all are Sumitomo Chemical Industries Brand name), Oplus violet #
370, Oplus Violet # 732 (both are trade names manufactured by Orient Chemical Industries).

Blue dye Macrolex Blue RR (trade name, manufactured by Bayer AG),
Blue BO, Blue # 8B (both brand names manufactured by Chuo Gosei Kagaku), Samiplast Blue OR, Samiplast Blue GP,
Samiplast Blue S (all trade names manufactured by Sumitomo Chemical Co., Ltd.), Oplus Blue IIN, Oplus Blue # 630 (all trade names manufactured by Orient Chemical Co., Ltd.).

Green dye Macrolex Green 5B, Macrolex Green G (both are brand names manufactured by Bayer AG), Green # 550,
Green # 201 (both are trade names manufactured by Chuo Gosei Kagaku)
Samiplast Green G (trade name, manufactured by Sumitomo Chemical Co., Ltd.), Oplus Green # 502, Oplus Green # 503
(All are trade names manufactured by Orient Chemical Industries).

Brown dye Brown PB, Brown SG (both are trade names manufactured by Chuo Gosei Kagaku), Oplus Brown # 430, Oplus Brown # 431 (both are trade names manufactured by Orient Chemical Industries).

The amount of the oil-soluble dye used varies depending on the desired degree of coloring concentration, but is usually used in a proportion of 1 to 20 parts by weight, preferably 2 to 15 parts by weight, per 100 parts by weight of the monomer. You.

The latter method of dyeing the resin particles after polymerization with a dye is carried out, for example, by dispersing the resin particles together with a dispersible dye described later in an aqueous medium and stirring the mixture at a predetermined temperature for a predetermined time.

The temperature at the time of dyeing is not particularly limited, but is preferably in the range of the glass transition temperature of the polymer constituting the resin particles or the glass transition temperature + 40 ° C.

The reason why the temperature at the time of dyeing is preferably within the above range is as follows. That is, if the temperature is lower than the glass transition temperature of the polymer constituting the resin particles, it may not be possible to dye to a desired coloring concentration or it may take a long time to dye. May fuse to form a lump.

Examples of dispersible dyes used for dyeing include azo dyes, anthraquinone dyes, indigoid dyes, sulfur dyes, and phthalocyanine dyes. It is preferable that the dispersible dye has a high affinity for a polymer constituting the resin particles and can dye the resin particles firmly. The amount of the disperse dye used varies depending on the desired degree of the coloring concentration, but is usually preferably at least 2% by weight, particularly preferably at least 4% by weight, based on the resin particles.

Water is usually used as the aqueous medium, but if the dispersibility of the resin particles and the dye is poor, a small amount of an appropriate organic solvent may be added. The amount of the aqueous medium used is the resin particles 10
It is preferably at least 500 parts by weight based on 0 parts by weight.

In order to adsorb the cationic surfactant on the surface of the resin particles colored by either of the above two methods, the resin particles may be treated with the cationic surfactant. The above treatment is performed in a liquid that negatively charges the toner surface, such as water, a water-miscible organic solvent, or a mixture of water and a water-miscible organic solvent.

Various conventionally known cationic surfactants can be used. That is, examples of the cationic surfactant include aliphatic amine salts, aliphatic quaternary ammonium salts, benzalkonium salts, benzethonium chloride, pyridinium salts, and imidazolinium salts.
In particular, an aliphatic quaternary ammonium salt represented by the following general formula [VII] is preferably used.

Note that one of the groups R ^{12 to} R ^{15 in} the above formula has a carbon number of
It is preferably a linear alkyl group having 12 or more, particularly 12 to 15 carbon atoms. If all of the groups R ^{12 to} R ¹⁵ have 11 or less carbon atoms, the toner for electrophotography may not be made hydrophobic and the environmental charging stability may not be improved.

Examples of the water-miscible organic solvent include lower aliphatic alcohols such as methyl alcohol, ethyl alcohol, and isopropyl alcohol; lower aliphatic carboxylic acids such as acetic acid and propionic acid; lower aliphatic carboxylic acids such as methyl acetate and ethyl acetate; Lower alkyl esters include aliphatic or alicyclic ethers such as tetrahydrofuran, dioxane and diisopropyl ether; and dialkyl ketones such as acetone and methyl ethyl ketone.

The electrophotographic toner obtained as described above may be dusted with carbon black, hydrophobic silica or the like, if necessary.

<Example> Hereinafter, the present invention will be described based on examples and comparative examples.

Example 1 First, 400 parts by weight of water and 6 parts by weight of sodium polyacrylate were placed in a reaction vessel, stirred and uniformly dissolved, and then a mixture of the following components was charged.

Monomer: styrene 80 parts by weight butyl methacrylate 20 parts by weight divinylbenzene 1.8 parts by weight 2-ethylene glycol dimethacrylate 1.5 parts by weight Polymerization initiator: 2,2'-azobis (2,4-dimethylvaleronitrile) 10 parts by weight Pigment: carbon black (trade name: MA-100, manufactured by Mitsubishi Kasei Co., Ltd.) 5 parts by weight Offset inhibitor: low molecular weight polypropylene (trade name: Viscol 550P, manufactured by Sanyo Chemicals Co., Ltd.) 2 parts by weight The mixture was stirred using a homomixer, and the monomers were granulated into oil droplets of about 10 μm at 80 ° C.
For 10 hours.

After completion of the reaction, the reaction product is filtered off from the reaction solution, and diluted hydrochloric acid is added.
After treating with 400 parts by weight, washing and drying were performed to obtain black resin particles having a particle size of about 10 μm.

Next, 100 g of the obtained resin particles was added to an aqueous solution of cetyl methyl ammonium chloride as a cationic surfactant.
After dispersing in 1 kg (concentration: 0.1% by weight) and adsorbing cetyl methyl ammonium on the surface of the resin particles, the resin particles were separated by filtration, washed with distilled water several times, and dried to obtain an electrophotographic toner.

The toner for electrophotography thus obtained is mixed with a ferrite carrier to prepare a developer (toner concentration: 3% by weight), and its blow-off charge is measured by a blow-off type charge meter (Toshiba Chemical Corporation). Made at −21.2 μC / g under conditions of normal temperature and normal humidity (20 ° C., 65%).
It was -19.3 μC / g under conditions of high temperature and high humidity (35 ° C., 85%), and it was confirmed that the charge amount hardly changed due to environmental changes.

When the above developer was used in an electrostatic copying machine (Model No. DC-1205 manufactured by Mita Kogyo Co., Ltd.), copying was performed under the same normal temperature and normal humidity conditions and high temperature and high humidity conditions. In the case of the above, a good image was obtained.

Further, after performing 100,000 continuous copying (running test) in the above electrostatic copying machine, the ferrite carrier was separated from the developer and washed with methyl alcohol to obtain a washing liquid. The washing solution was concentrated, developed on a silica gel thin phase using an acetone-concentrated aqueous ammonia mixture medium, and analyzed using a thin-phase automatic detection device (trade name: Iatroscan MK-5 manufactured by Yatron). Although very little cetyl methyl ammonium was detected, the image hardly changed before and after the running test.

Example 2 An electrophotographic toner was obtained in the same manner as in Example 1 except that 1 kg of an aqueous solution of dodecyl ammonium bromide (concentration: 0.1% by weight) was used instead of 1 kg of an aqueous solution of cetyl methyl ammonium chloride. A developer (toner concentration 3% by weight) was prepared by mixing with a carrier.

The blow-off charge amount of this developer was measured using the above-mentioned blow-off type charge amount measuring device. Under normal temperature and normal humidity (20 ° C., 65%) conditions, −31.9 μC / g, high temperature and high humidity ( 35
(° C., 85%) was −28.3 μC / g, and it was confirmed that the charge amount hardly changed due to environmental changes.

Further, when the above developer was used in the electrostatic copying machine and copying was performed under the same normal temperature and normal humidity conditions and high temperature and high humidity conditions, a good image was obtained in any case. Was.

Comparative Example 1 A developer having a toner concentration of 3% by weight was prepared in the same manner as in Example 1 except that the resin particles were not treated with the cetyl methyl ammonium chloride aqueous solution.

The blow-off charge amount of the developer was measured using the blow-off type charge amount measuring device, and was −28.6 μC / g under the condition of normal temperature and normal humidity (20 ° C., 65%).
Under conditions of high temperature and high humidity (35 ° C, 85%), the temperature decreased to -17.3 μC / g.

Further, when the above developer was used for copying in the electrostatic copying machine, a normal image was obtained although the image density was slightly lower under the same normal temperature and normal humidity conditions, but the high temperature and high humidity conditions were obtained. With the condition paper, fog was remarkable and a normal image could not be obtained.

Comparative Example 2 First, 400 parts by weight of water, 6 parts by weight of tricalcium phosphate and sodium dodecylbenzenesulfonate were placed in a reactor.
After stirring, the mixture was uniformly dissolved, and then a mixture of the following components was added.

Monomer: styrene 80 parts by weight butyl methacrylate 20 parts by weight divinylbenzene 1.8 parts by weight 2-ethylene glycol dimethacrylate 1.5 parts by weight Polymerization initiator: 2,2'-azobis (2,4-dimethylvaleronitrile) 10 parts by weight Pigment: carbon black (trade name: MA-100, manufactured by Mitsubishi Kasei Co., Ltd.) 5 parts by weight Charge control agent: hexadecyltrimethylammonium tridecane 1 part by weight Offset inhibitor: low molecular weight polypropylene (trade name: Viscol 550P manufactured by Sanyo Chemical Co., Ltd.) 2 parts by weight) Next, the above mixed solution was stirred using a homomixer,
The monomer was granulated into oil droplet particles of about 10 μm and reacted at 80 ° C. for 10 hours.

After completion of the reaction, the reaction product is filtered off from the reaction solution, and diluted hydrochloric acid is added.
After treatment with 400 parts by weight, washing and drying were performed to obtain a black electrophotographic toner having a particle size of about 10 μm, and this was mixed with a ferrite carrier to prepare a developer (toner concentration: 3% by weight). .

The blow-off charge amount of this developer was measured using the above-mentioned blow-off type charge amount measuring device, and was found to be −18.8 μC / g under normal temperature and normal humidity (20 ° C., 65%). 35
-18.0 μC / g under the conditions of (° C., 85%), and it was confirmed that the charge amount hardly changed due to environmental changes.

Further, when the above developer was used in the electrostatic copying machine and copying was performed under the same normal temperature and normal humidity conditions and high temperature and high humidity conditions, a good image was obtained in any case. Was.

Then, when 100,000 sheets of continuous copying were performed in the above-mentioned electrostatic copying machine, fogging of the image became remarkable from around 70,000 sheets, and a large amount of toner scattering was confirmed in the developing section of the copying machine.

Further, after performing the above continuous copying, the ferrite carrier is separated from the developer, washed with methyl alcohol,
A washing solution was obtained. This washing solution was concentrated, developed on a silica gel thin phase using a chloroform-methyl alcohol-formic acid mixed medium, and analyzed by a thin phase automatic detection device. As a result, a large amount of tridecanoic acid was detected. From this,
Hexadecyltrimethylammonium tridecanoate compounded as a charge control agent in the toner is separated from the toner and transferred to the carrier during repeated image formation, deteriorating the chargeability of the developer, and causing the fog and toner scattering. It was presumed to have occurred.

<Effect of the Invention> Since the electrophotographic toner of the present invention is configured as described above, the charge control agent does not separate from the toner and migrate to the carrier during repeated image formation. It also has excellent environmental charging stability. In addition, according to the production method of the present invention, the monomer is suspension-polymerized to obtain resin particles, and the treatment with a cationic surfactant only allows the cationic surfactant to be adsorbed on the surface of the resin particles. As a result, the charge control agent can be formed, so that the electrophotographic toner of the present invention can be efficiently produced.

Claims (12)

(57) [Claims] 1. A granular toner having a carboxylate group on the surface, obtained by subjecting a monomer to suspension polymerization in water in which an alkali metal salt of a polycarboxylic acid is dissolved, and comprising a cationic interface on the surface. A toner for electrophotography, wherein a charge control agent is formed on the surface by adsorption of an activator. 2. The electrophotographic toner according to claim 1, wherein the cationic surfactant is an aliphatic quaternary ammonium salt. 3. The electrophotographic toner according to claim 2, wherein one of the substituents of the aliphatic quaternary ammonium salt is a linear alkyl group having 12 or more carbon atoms. 4. The alkali metal salt of a polycarboxylic acid is a polymer of an alkali metal (meth) acrylate.
The toner for electrophotography according to the above. 5. The electrophotographic toner according to claim 1, wherein the alkali metal salt of the polycarboxylic acid is a copolymer of an alkali metal (meth) acrylate and another monomer. 6. Resin particles are obtained by subjecting a monomer that is hardly soluble or insoluble in water to suspension polymerization in water in which an alkali metal salt of polycarboxylic acid is dissolved, to obtain resin particles. And a method for producing an electrophotographic toner. 7. The method for producing an electrophotographic toner according to claim 6, wherein the obtained resin particles are previously treated with an acid and then treated with a cationic surfactant. 8. The method according to claim 6, wherein the cationic surfactant is an aliphatic quaternary ammonium salt. 9. The method for producing an electrophotographic toner according to claim 8, wherein one of the substituents of the aliphatic quaternary ammonium salt is a linear alkyl group having 12 or more carbon atoms. 10. The electrophotographic toner according to claim 6, wherein the treatment of the resin particles with the cationic surfactant is performed in water, a water-miscible organic solvent, or a mixture of water and a water-miscible organic solvent. Manufacturing method. 11. An alkali metal salt of a polycarboxylic acid,
7. The method for producing an electrophotographic toner according to claim 6, wherein the toner is a polymer of an alkali metal (meth) acrylate. 12. An alkali metal salt of a polycarboxylic acid,
7. The method for producing an electrophotographic toner according to claim 6, which is a copolymer of an alkali metal (meth) acrylate and another monomer.