JPH0315861A - Production of polymerized toner - Google Patents

Abstract

PURPOSE:To obtain the polymerized toner which has a high image density and is free from fogging by previously melting and kneading a carbon black with a thermoplastic resin to finely dispersing the carbon black to a specific state and dissolving and dispersing the dispersion into a polymerizable monomer. CONSTITUTION:The carbon black is previously melted and kneaded with the thermoplastic resin to finely disperse the carbon black to <=0.2mum number average dispersion particle size. The particles are dissolved and dispersed into the polymerizable monomer. Namely, the dispersion average particle size of the carbon black in the polymerizable monomer is sufficiently reduced to eliminate the deviation in the carbon black contents in the respective particles of the polymer obtd. by emulsion polymn. and flocculation in a dispersion medium which is substantially incompatible with the polymerizable monomer. The sharp electrostatic charge quantity distribution is obtd. and the generation of the fogging is obviated when this toner is used as the toner. The sufficiently high image density is thus obtd. by the improved dispersibility of the carbon black.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for producing polymerized toner. More specifically, the present invention relates to a method for producing a polymerized toner with high image density and no fog.

[Prior Art] Conventionally, there is a method for producing a polymerized toner in which carbon black is dispersed in a polymerizable monomer and then emulsion polymerized in a dispersion medium that is substantially incompatible with the polymerizable monomer. .

[Problems to be Solved by the Invention] However, in this technique, the dispersed average particle size of carbon black in the polymerizable monomer is coarse, and carbon black in a dispersion medium that is substantially incompatible with the polymerizable monomer is This results in large deviations in the carbon black content in each particle of the polymer obtained by emulsion polymerization in The image density cannot be obtained.

[Means for Solving the Problems] The present inventor has arrived at the present invention as a result of extensive studies regarding a method for producing a polymerized toner with high image density and no fog.

That is, the present invention provides a method for producing a polymerized toner from a polymerizable monomer containing carbon black by emulsion polymerization, in which carbon black (A) is preliminarily treated with a thermoplastic resin (
Carbon black is finely dispersed to a number average dispersed particle size of 0.2 μm or less by melt-kneading with B), and this is dissolved and dispersed in a polymerizable monomer (C). It is a manufacturing method.

In the present invention, carbon black (A) that has a specific surface area of 8 h"/g or more as determined by BET can be used. Preferably, a carbon black that has a specific surface area of +301/g or more is used.

Surface-treated carbon black can also be used. Examples of surface treatments include polymer grafting, surface oxidation treatment, and surface adsorption treatment. These can be done in the usual way.

In the present invention, the thermoplastic resin (B) is a copolymer consisting of a styrene monomer, a (meth)acrylic monomer and/or a maleic acid monomer, and an amino group-containing monomer ( Examples include co)polymers.

Examples of styrenic monomers include styrene and styrene-substituted monomers (
Alkylstyrenes such as α-methylstyrene, o-,
m- or p-methylstyrene, p-ethylstyrene,
2,4-dimethylstyrene, p-n-'tilstyrene,
p"tert-butylstyrene, p-n-hexylstyrene, p-11-octylstyrene), and the like.

Among these, styrene is preferred.

Examples of (meth)acrylic monomers include alkyl (
meth)acrylate [alkyl having 1 to 18 carbon atoms, such as methyl (meth)acrylate, ethyl (meth)acrylate, n- or tobutyl (meth)acrylate], n-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, ) acrylate, lauryl (meth)acrylate and stearyl (meth)acrylate], hydroxyl group-containing (meth)acrylate [hydroxylethyl (meth)acrylate, etc. Among these, methyl (meth)acrylate, ethyl (meth)acrylate, n- or I-
Butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and mixtures of two or more thereof.

Examples of the maleic acid monomer include maleic acid; maleic anhydride; and maleic acid derivatives such as dialkyl maleate (phthyl maleate, 2-ethylhexyl maleate, etc.). Among these, maleic acid dialkyl esters are preferred.

Examples of amino group-containing monomers include amino group-containing (meth)acrylates [dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, etc.]
Examples include amino group-containing (meth)acrylamide [N,N-dimethylacrylamide, etc.].

Styrenic monomer and (meth)acrylic monomer and/or
Alternatively, in the case of a copolymer consisting of a maleic acid monomer, an amino group-containing monomer may be included as a copolymerization component.

In the case of a (co)polymer consisting of an amino group-containing monomer, a styrene monomer, (meth)acrylic monomer, or maleic acid monomer can also be included as a copolymerization component.

The thermoplastic resin (B) can also contain other monomers as copolymerization components. Other monomers include (meta)
Acrylic acid, vinyl esters (vinyl acetate, vinyl propionate, etc.), aliphatic hydrocarbon vinyl monomers (butadiene, etc.), nitrile compounds (acrylonitrile,
methacrylonitrile, etc.), vinyl ethers (vinyl methyl ether, vinyl ethyl ether, vinyl isobutyl ether, etc.), vinyl ketones (vinyl methyl ketone, vinyl hexyl ketone, etc.), N-vinyl compounds (N
-vinylpyrol, N-vinylcarpazole, N-vinylindole, N-vinylpyrrolidone, etc.), vinyl halides (vinyl chloride, etc.), and the like.

As other monomers, monomers having at least two polymerizable double bonds may be copolymerized to obtain a polymer having a crosslinked structure and a higher molecular weight. Examples of the polyfunctional monomer include di- or polyvinyl compounds (divinylbenzene, divinyltoluene, ethylene glycol diacrylate, I,G-hexanediol diacrylate, trimethylolpropane triacrylate, etc.).

When the thermoplastic resin (B) is a copolymer of a monomer consisting of a styrene monomer and a (meth)acrylic monomer and/or a maleic acid monomer, the styrene monomer and The weight ratio of the (meth)acrylic monomer and/or maleic acid monomer is usually 100:5 to J00, preferably 100:5 to 80, particularly preferably 100.
:1G to 50. (meth)acrylic monomer and/or
If the maleic acid monomer content is less than 5, the lower limit fixing temperature will be too high to be used in practical use as a toner; if it exceeds 100, the glass transition point will be low and the toner will have poor storage stability.

The amount of each monomer in the total monomer is based on the weight of the total monomer when it consists of a styrene monomer, a (meth)acrylic monomer, and/or a maleic acid monomer. System monomer usually 45-95%, preferably 60-90%
, (meth)acrylic monomer and/or maleic acid monomer usually 5 to 45%, preferably IO to 40%, other monomers usually 10% or less, preferably 5% or less, polyester. The amount of functional monomer is usually 3% or less, preferably 1% or less.

In the case where the thermoplastic resin (B) is composed of the amine 7 group-containing monomer b, the weight ratio of the amine 7 group-containing monomer to other monomers is usually t00:0 to 900, preferably 100:100.
~400.

When the amount of each monomer in the total monomers consists of amino group-containing monomers, the amount of amino group-containing monomers is usually 10 to 100%, preferably 20 to 50%, based on the weight of all monomers. %
, other monomers are usually θ~90%, preferably 50~80%
%, polyfunctional monomer is usually 3% or less, preferably 1% or less.

When the amount of polyfunctional monomer exceeds 3%, the IF becomes high;
Melting and kneading requires a large amount of energy.

The number average molecular weight of the thermoplastic resin (B) is usually 1. 000
~400,000, preferably 1,500-30.00
0 or 70,000 to 300,000, particularly preferably 2,500 to 20,000.

The molecular weight distribution of the thermoplastic resin (B) may exhibit either a single peak or two or more peaks.

The thermoplastic resin (B) may have a crosslinked structure.

When melting and kneading carbon black (A) and thermoplastic resin (B), magnetic powder (ferromagnetic metal powder such as iron, cobalt, nickel, or magnetite, hematite, ferrite, etc.) may be added to the thermoplastic resin (B) as necessary. (compound) can be dispersed by melt-kneading. These magnetic powders may be treated with a resin such as a silane coupling agent or a titanium coupling agent. The magnetic powder may be melt-kneaded before or after the carbon black is melt-kneaded, or may be melt-kneaded simultaneously.

Furthermore, low molecular weight polyolefin wax can be uniformly dispersed in the thermoplastic resin (B) for the purpose of preventing offset, improving fluidity, improving fixing properties, etc. Examples of this low molecular weight polyolefin wax include (a): polyethylene, polypropylene, ethylene-α-olefin (3 to 8 carbon atoms) copolymer (e.g. 50% by weight or more of ethylene, especially 70% by weight or more) (
(c) = (a) maleic acid derivative (maleic anhydride, maleic acid dimethynoester, maleic acid diethyl ester, maleic acid di-2-ethylhexyl ester, etc.) adduct, (c) = oxidation of (a) (2): Ethylenically unsaturated carboxylic acids [(meth)acrylic acid, itaconic acid, etc.] and/or their esters [alkyl (C, -C) esters, etc.] and ethylenically unsaturated hydrocarbons (ethylene, Examples include copolymers with propylene, butene, etc.) and mixtures of two or more of these.

Among the above low molecular weight polyolefin waxes, (a) is a high molecular weight polyolefin (the molecular weight is usually 10,000 to 2
,000,000), or by monopolymerizing or copolymerizing olefins. (0 can be obtained by addition-reacting a low molecular weight polyolefin wax and a maleic acid derivative in the presence of a peroxide catalyst or in the absence of a catalyst. It can be obtained by oxidizing with ozone-containing oxygen or ozone-containing gas (air).

The acid value of the oxide is usually 100 or less, preferably 50 or less. (2) is obtained by copolymerization of ethylenically unsaturated carboxylic acid and/or its alkyl ester ((+ to C) and ethylenically unsaturated hydrocarbon. Ethylenically unsaturated carboxylic acid and/or its alkyl ester The amount is usually 30% or less, preferably 20% or less on a weight basis.

The molecular weight of the polyolefin wax was determined by GPC (gel permeability chromatography) using 0-
The measurement can also be carried out using dichlorobenzene at 135°C.

As a method for uniformly dispersing the low molecular weight polyolefin wax in the polymer, it can be dispersed by melt mixing the low molecular weight polyolefin wax and the polymer.

The low molecular weight polyolefin wax may be melt-kneaded before or after the carbon black is melt-kneaded, or may be melt-kneaded simultaneously.

Another method for uniformly dispersing a low molecular weight polyolefin wax in a polymer is to add the low molecular weight polyolefin wax during the production of the above polymer (when producing the styrenic polymer or styrene/acrylic polymer). can. Specifically, a method is employed in which the polyolefin wax is mechanically made into fine particles and then added to the monomer, or a method in which the polyolefin wax is melted in a heated monomer and dispersed by stirring.
Furthermore, various additives [a charge control agent (metal complex, nigrosine, etc.), a lubricant (such as polytetrafluoroethylene, fatty acid or metal salt, or amide)] may be added to the polymer as necessary. Note that these can also be used by being mixed (externally added) with toner particles.

The amount of carbon plaque (A) during melt-kneading is 10 to 100%, preferably 20 to 45% of the thermoplastic resin (B).

The amount of magnetic powder is usually 0 to 60% of the total of (B), (C), and other components if necessary.

The amount of polyolefin wax is usually 40% or less, preferably 30% or less of the total of (B), (C) and other components if necessary. If the amount of polyolefin wax exceeds 40%, dispersion will be insufficient.

The amount of other additives is usually 0 to 15%.

Carbon black is finely dispersed to a number average dispersed particle diameter of 0.2 μm or less. When the particle size exceeds 0.2 μm, fogging occurs and image density decreases. The particle size can be confirmed by electron micrograph.

For melt-kneading carbon black (A), thermoplastic resin (B), and other components if necessary, a general kneading machine such as a two-wheel extruder, three-roll extruder, or Laboplast mill is used.

The temperature during melt-kneading is usually 70 to 210°C, preferably 1
The temperature is 10-180°C.

In the present invention, the polymerizable monomer (C) consists of a styrene monomer, a (meth)acrylic monomer and/or a maleic acid monomer, and a monomer containing an amino group. can be mentioned.

The styrene monomers, (meth)acrylic monomers, maleic acid monomers, and amino group-containing monomers are the same as those listed in the thermoplastic resin (R) section. and preferred ones are also the same.

In the case of monomers consisting of styrene monomers, (meth)acrylic monomers and/or maleic acid monomers, amino group-containing monomers can also be included.

In the case of monomers consisting of amino group-containing monomers, styrene monomers, (meth)acrylic monomers, and maleic acid monomers can also be included.

The polymerizable monomer (C) can also contain other monomers. As other monomers, the same monomers as those described in the section of thermoplastic resin (B) can be mentioned.

As other monomers, monomers having at least two polymerizable double bonds can also be included in order to obtain a polymer with a higher molecular weight. Examples of this polyfunctional monomer include those similar to the polyfunctional polymerizable monomers described in the section of thermoplastic resin (B).

In the case where the polymerizable monomer (C) consists of a styrene monomer, a (meth)acrylic monomer and/or a maleic acid monomer, the styrene monomer and the (meth)acrylic monomer The weight ratio of maleic acid monomer and/or maleic acid monomer is usually
100:5~I Go1 Preferably 100:10~
It is 5G. If the content of the (meth)acrylic monomer and/or maleic acid monomer is less than 5, the minimum fixing temperature will be too high and it cannot be used as a toner. If it exceeds 100, the glass transition point will be low and the toner will have poor storage stability. becomes worse.

The amount of each monomer in the total monomer is based on the weight of the total monomer when it consists of a styrene monomer, a (meth)acrylic monomer, and/or a maleic acid monomer. System monomer usually 45-95%, preferably 60-90%
, (meth)acrylic monomer and/or maleic acid monomer, usually 5 to 45%1, preferably 10 to 40%, other monomers usually 10% or less, preferably 5% or less, polyester. The amount of functional monomer is usually 1% or less, preferably 0.5% or less.

When the polymerizable monomer (C) consists of a monomer containing 7 amino groups, the weight ratio of the monomer containing amino groups to other monomers is usually 100:100 to 900, preferably 100:1. 50-400.

When the amount of each monomer in the total monomers consists of monomers containing 7 amino groups, the amount of the monomers containing amino groups is usually 10 to 50%, preferably 20 to 50%, based on the weight of all monomers. 40%,
Other monomers are usually 50-90%, preferably 60-80%
%, polyfunctional monomer is usually 1% or less, preferably 0.5
% or less.

If the amount of the polyfunctional monomer exceeds 1%, the toner becomes too expensive to be used in practical use as a toner.

The amount of carbon black (A) is 5 to 1 in all polymerizable monomers.
5% by weight, preferably 7-10% by weight.

The amount of thermoplastic resin (B) is usually 55% or less, preferably 45% or less, particularly preferably 30% or less, based on the weight of all polymerizable monomers. If the amount of the thermoplastic resin (B) exceeds 55%, the viscosity of the polymerizable monomer will increase and the dispersed particle size during suspended S polymerization will become coarse.

The amount of magnetic powder is usually 0 to 50% by weight based on the total polymerizable monomers.

The amount of polyolefin wax is usually 30% or less, preferably 20% or less, based on the weight of total polymerizable monomers. If the amount of polyolefin wax exceeds 30%, dispersion will be insufficient.

The amount of other additives is usually 0 to 5%.

Emulsion polymerization of polymerizable monomers uses an emulsifier and, if necessary, a dispersion stabilizer, to disperse and emulsify fine particles in a liquid dispersion medium that is substantially incompatible with the monomer, such as water, and perform water-soluble polymerization. This is carried out using an initiator or a combination of a water-soluble initiator and an oil-soluble initiator, with the addition of a chain transfer agent if necessary.

As the emulsifier, anionic surfactants, cationic surfactants, amphoteric surfactants, and nonionic surfactants can be used.

Examples of anionic surfactants include fatty acid salts (sodium oleate, etc.), alkyl sulfate salts (sodium lauryl sulfate, ammonium lauryl sulfate, etc.), alkylbenzene sulfonates (sodium dodecylbenzenesnolephonate, etc.), and alkylnaphthalene sulfonates. , dialkyl sulfosuccinates, alkyl phosphate ester salts, naphthalene sulfonic acid formalin condensates, polyoxyethylene alkyl sulfate ester salts, and the like.

Examples of the cationic surfactant include alkylamine salts (laurinoleamine acetate, stearinoleamine acetate, etc.), quaternary ammonium salts (lauryltrimethylammonium chloride, stearyltrimethylammonium chloride, etc.), and the like.

Examples of the amphoteric surfactant include lauryl trimethynoleammonium chloride.

Examples of nonionic surfactants include polyoxyethylene alkyl ether, polio. xyethylene alkylphenol ether, polyoxyethylene fatty acid ester,
Examples include sorbitan fatty acid ester, polyoxysorbitan fatty acid ester, polyoxyethylene alkylamine, glycerin, fatty acid ester, oxyethylene-oxypropylene block polymer, and the like.

Anionic surfactants are preferred.

Dispersion stabilizers include water-soluble polymers (gelatin, gum tragacanth, starch, methylcellulose, hydroxyethylcellulose, carboxymethylcellulose, polyvinyl alcohol, polyvinylpyrrolidone, polyacrylates, etc.), poorly soluble fine powder inorganic compounds (barium sulfate, Calcium sulfate, barium carbonate, calcium carbonate, magnesium carbonate, calcium phosphate, talc, bentonite, diatomaceous earth, clay, etc.).

The amount of emulsifier used is usually 0.01 to 1 based on the weight of water.
0%, preferably 0.05 to 4%.

The amount of dispersion stabilizer is usually 0-2%, preferably 0.1-1%, based on the weight of water.

Examples of water-soluble initiators include ammonium persulfate, potassium persulfate, sodium metabisulfite, hydrogen peroxide,
Examples include t-butyl hydroperoxide, cumene hydroperoxide, 4,4'-azobiscyanovaleric acid, and mixtures of two or more thereof.

Examples of oil-soluble initiators include penzoyl peroxide, lauroyl peroxide, 1, tobis(t-butylbaroxy)3,
, 3.5-}limethylcyclohexane, 2,2'-azobisisobutyronitrile, 2.2'-azobis(2.4
monomethylvaleronitrile), and mixtures of two or more thereof.

The molar ratio of the water-soluble initiator to the oil-soluble initiator is usually 0 to 2,000, preferably 0 to 100, particularly preferably 20 to 50, of the oil-soluble initiator to 100 of the water-soluble initiator.

The amount of the polymerization catalyst used is usually 0.01-10%, preferably 0.1-5%, based on the weight of the total polymerizable monomers.

Examples of the chain transfer agent include mercabutane compounds, nologen compounds, and α-methylstyrene dimer.

The amount of chain transfer agent is usually 5% or less, preferably 1% or less, based on the total weight of all polymerizable monomers.

The polymerizable monomer concentration of the dispersion is usually 5 to 50% by weight, preferably 10 to 45% by weight, particularly preferably 20 to 4% by weight.
It is 0% by weight.

A method for dispersing and emulsifying the polymerizable monomer in a dispersion medium includes a method of mechanical stirring (for example, a method using a homomixer homogenizer), a method using ultrasonic waves, etc., and any of these methods may be used.

As a typical dispersion emulsification method, when a homomixer is used, stirring conditions are such that the stirring rotation speed is usually 1000 rpm≦. The temperature is usually 10 to 50°C. Stirring time is usually 1
~30 minutes.

Emulsion polymerization is carried out under a nitrogen stream and with stirring.

The polymerization temperature is usually 40 to 140°C, preferably 60 to 12°C.
It is 0°C. The polymerization time is usually 2 to 30 hours, preferably 4 to 20 hours.

After the polymerization is completed, the emulsion polymer is aggregated to the size of a toner.

Coagulation is carried out by dropping a coagulant into the polymer solution while stirring.

Examples of flocculants include inorganic acids (such as hydrochloric acid and sulfuric acid), organic acids (such as oxalic acid and formic acid), and water-soluble metal salts (such as those consisting of an acid and an alkali metal, and those consisting of an acid and aluminum). Particularly preferred are magnesium chloride, calcium chloride, sodium chloride, magnesium sulfate and hydrochloric acid. These may be used alone or in combination.

The amount of flocculant is usually 20 to 35 parts by weight per 100 parts by weight of emulsifier.
Use 0 parts by weight.

The flocculant is usually used as a 0.5 to IO weight % aqueous solution.

After coagulation, wash with water, filter, and dry under reduced pressure to reduce the average particle size to 3.
A non-spherical polymerized toner of ~20μ can be obtained.

The particle size can be confirmed using a particle size distribution measuring device (such as a light transmission type particle size distribution measuring device).

The glass transition point of the polymer in the polymerized toner obtained in the present invention is usually 40 to 80°C, preferably 45 to 70°C.

If the glass transition point is less than 40°C, the toner will have poor storage stability, and if it exceeds 80°C, the temperature will be too high and it will not be suitable for practical use as a toner.

Molecular Weight Distribution of Polymer in Toner [The ratio of weight average molecular weight to number average molecular weight (My/Mn) is usually 10 or more, and preferably 20 or more for a binder for electrophotographic toner. If the molecular weight distribution is less than 10, the temperature at which offset occurs (1!O) and the minimum fixing temperature (MF)
becomes unbalanced.

The weight average molecular weight of the tetrahydrofuran (T}IF-soluble portion of the polymer such as styrene/acrylic acid ester or styrene/maleic ester in the toner is usually IxlG
'~1xlO', preferably 5xlO'' ~1xlO
'is. When the molecular weight is less than 1xlG', the glass transition point (
Tg) decreases, blocking characteristics worsen, and I
If the temperature exceeds XIO'', the minimum fixing temperature (IF) becomes too high when a heat roller is used to fix the electrostatic latent image visualized with toner.

The molecular weight can be expressed as a weight average using gel permeacylon (GPC) using THF as a solvent and converted to standard polystyrene.

The polymerized toner in the present invention is used by being fixed on a support (paper, polyester film, etc.), and as a fixing method, a known hot roll fixed fixing method or a pressure fixing method can be applied. In particular, it can be preferably applied to a hot roll fixing method.

[Example] The present invention will be further explained below with reference to Examples, but the present invention is not limited thereto. Parts in the examples are parts by weight.

Synthesis example l 720 parts of styrene, 1 part of 2-ethylhexyl acrylate
A mixed solution of 90 parts of methyl methacrylate and 6.5 parts of divinylbenzene (solution 1-1), a solution of 8.5 parts of 2,2'-azobisisobutyronitrile and 250 parts of toluene [ (Solution!-2) and a solution [(Solution 1-3)] of 2 parts of 2,2'-azobisisobutyronitrile and 55 parts of toluene were prepared. 250 parts of toluene was charged into a reactor equipped with a thermometer, a stirrer, a gas inlet tube, a dropping funnel, and a cooling tube. The system was purged with nitrogen and maintained under a nitrogen atmosphere thereafter. The temperature was raised while stirring, and (Solution 1-1) and (Solution 2) were added dropwise over 4 hours while refluxing toluene, and the mixture was further refluxed for 2 hours. Thereafter, (solution 1-3) was added twice every hour to complete the polymerization. After distilling off the solvent, the glass transition point was 61°C.
, number average molecular weight 11,000, weight average molecular weight 30G,
000 vinyl polymer was obtained. This polymer is referred to as a thermoplastic resin (B-1).

Example l 200 parts of carbon black MAIOO (manufactured by Mitsubishi Kasei),
After powder mixing 800 parts of thermoplastic resin (B-1) and 800 parts of thermoplastic resin (B-1), the mixture was heated at 150°C and at a rotation speed of 10 to 7 in a laboplast mill.
The mixture was melt-kneaded for 30 minutes at ORPM. When the cross section was observed with an electron microscope, carbon black was 0.02 μm to 0.
．． It had a dispersed particle size distribution of 2 μm, and its number average dispersed particle size was 0.04 μm. The above polymer slightly enriched with carbon black is used as a thermoplastic resin (B=2).

875 parts of thermoplastic resin (B-2), Viscoel GIlf
OP (low molecular weight polypropylene manufactured by Sanyo Chemical Industries)! 0
0 parts and Bontron 10 (manufactured by Orient Chemical) 25
After mixing the parts into powder, use the Laboplast Mill! The mixture was melt-kneaded for 30 minutes at 40° C. and a rotational speed of 10 to 70 rpm. The above polymer in which carbon black and viscol [i60 P are finely dispersed is referred to as a thermoplastic resin (B-3).

Styrene 504g, 2-ethylhexyl acrylate 7
6 parts, 120 parts of methyl methacrylate, 2.2'-
Thermoplastic resin (Ill-2) is obtained by mixing 2 parts of azobisisobutyronitrile and 10 parts of t-lauryl merbutane.
300 parts were dissolved and dispersed. This dispersion liquid is referred to as a polymerizable monomer composition (D-1). 1000 parts of the above polymerizable monomer composition (D-1) were mixed with 0.4% Aerosil #20G (manufactured by Nippon Aerosil) and 0.5% Newpol PE-68 (oxypropylene-oxyethylene block polymer manufactured by Sanyo Chemical Industries). %, and 1% of sodium totecylbenzenesulfonate, and the monomer composition was stirred at 30° C. with a homomixer at 10,000 rpm for 130 minutes to disperse the monomer composition.

Next, lθ part of potassium persulfate was added to the dispersion, and the temperature was raised under a nitrogen atmosphere while stirring at low speed with a paddle type stirrer, and the polymerization was carried out at 55°C for 5 hours, at 80°C for 5 hours, and at 75°C for 2 hours.
Add 200 parts of % potassium persulfate aqueous solution at 75°C.
Polymerization was carried out at 95° C. for 2 hours and then at 95° C. for 2 hours.

After the polymerization was completed, 400 parts of the polymerization solution was taken and added dropwise over 1 hour to 1000 parts of a 1% magnesium sulfate aqueous solution stirred with snow at 8000 rpm using a homomixer to cause agglomeration.

The aqueous medium containing the polymerized toner was cooled, washed with water, dehydrated, dried, and then classified using an air classifier to obtain a polymerized toner.

A polymerized toner having a particle size of Iμ1 to 15μ (average particle size 8μ) as measured by a Coulter counter was obtained in a yield of 78%.

When an image was formed using the polymerized toner thus obtained as a developer using a commercially available electrophotographic copying machine, a clear image with high image density was obtained without fogging.

Example 2 The thermoplastic resin (B-3) of Example I was added to m! ml! When doing so, carbon black MAIGO (manufactured by Mitsubishi Kasei), polymer (C-1), Viscol 660P (low molecular weight polypropylene manufactured by Sanyo Chemical Industries), and Bontron Fl-10
(manufactured by Orient Chemical Co., Ltd.) at the same time, the powder was mixed at the same time in a laboplast mill at 140°C and at a rotation speed of 10 to 70 rpm.
A polymerized toner was obtained in the same manner as in Example 1, except that the mixture was melt-kneaded for 50 minutes. When an image was formed using the polymerized toner thus obtained as a developer using a commercially available electrophotographic copying machine, a clear image with high image density and no fogging was obtained.

Comparative Example I Styrene 504 instead of polymerizable monomer composition (D-1)
7B parts of 2-ethylhexyl acrylate, 120 parts of methyl methacrylate, 2 parts of 2.2'-azobisisobutyronitrile and 10 parts of t-lauryl mercabutane, and carbon black MAIOO ( manufactured by Mitsubishi Kasei), thermoplastic resin (B-1), Viscoel HOP
(low molecular weight polypropylene manufactured by Sanyo Chemical Industries) and Bontron N-10 (manufactured by Orient Chemical).
10,000 rpm 240 in a homomixer at 30°C
Polymerizable monomer composition prepared by stirring for minutes (
A polymerized toner was obtained in the same manner as in Example 1 except that D-2) was used.

When an image was formed using the polymerized toner thus obtained as a developer using a commercially available electrophotographic copying machine, fogging and a decrease in image density were observed.

[Effects of the Invention] By the production method of the present invention, a polymerized toner without a decrease in image density and without fogging can be obtained. That is, the dispersed average particle size of carbon black in a polymerizable monomer is sufficiently reduced, and a polymer obtained by emulsion polymerization and aggregation in a dispersion medium that is substantially incompatible with the polymerizable monomer is obtained. To eliminate deviations in the carbon black content of each particle and produce a polymerized toner that, when used as a toner, has a sharp charge distribution, does not cause fogging, and provides sufficiently high image density by improving the dispersibility of carbon plaques. becomes possible.

Since it has the above effects, the toner obtained by the present invention is useful as a toner for electrophotography.

The styrene-acrylic type is useful as a negatively charged toner, and the amino group-containing type is useful as a positively charged toner.

? ■　--J

Claims (1)

[Claims] 1. In a method for producing a polymerized toner by emulsion polymerization from a polymerizable monomer containing carbon black, the carbon black (A) is melt-kneaded with a thermoplastic resin (B) in advance. Black is finely dispersed to a number average dispersed particle size of 0.2 μm or less, and this is mixed with polymerizable monomer (C
) A method for producing a polymerized toner by emulsion polymerization, characterized by dissolving and dispersing the toner. 2. The method according to claim 1, wherein the polymerizable monomer (C) comprises a styrene monomer, a (meth)acrylic monomer, and/or a maleic acid monomer. 3. The production method according to claim 1, wherein the polymerizable monomer (C) comprises a polymerizable monomer having an amino group. 4. The specific surface area of carbon black (A) is 80 m^2/
The manufacturing method according to any one of claims 1 to 3, wherein the amount is at least g. 5. Thermoplastic resin (B) that finely disperses carbon black
) is a copolymer consisting of a styrene monomer, a (meth)acrylic monomer and/or a maleic acid monomer. 6. The manufacturing method according to any one of claims 1 to 4, wherein the thermoplastic resin (B) is a (co)polymer consisting of an amino group-containing monomer. 7. Claims 1 to 7, wherein the thermoplastic resin (B) has a crosslinked structure.
6. The manufacturing method according to any one of 6. 8. According to any one of claims 1 to 7, the mixing weight ratio of carbon black (A) and thermoplastic resin (B) during melt-kneading is 10 to 100 parts by weight of carbon black to 100 parts by weight of (B). Manufacturing method. 9. The manufacturing method according to any one of claims 1 to 8, wherein two or more types of polymerization initiators are used in combination in the emulsion polymerization of the polymerizable monomer. 10. The production method according to any one of claims 1 to 9, wherein a water-soluble polymerization initiator alone or a water-soluble polymerization initiator and an oil-soluble polymerization initiator are used in the emulsion polymerization of the polymerizable monomer.