JPH02311852A - Production of polymerized toner - Google Patents

Abstract

PURPOSE:To obtain a polymerized toner ensuring high image density and not causing fogging by melting and kneading carbon black and a polymer and dissolving or dispersing the resulting polymer contg. finely dispersed carbon black of <=0.2mum number average particle size in a polymerizable monomer. CONSTITUTION:When a polymerized toner is produced by suspension- polymerizing a polymerizable monomer compsn. contg. a polymerizable monomer A, carbon black B and a polymer C, the carbon black B and the polymer C are melted and kneaded to obtain a polymer contg. finely dispersed carbon black of <=0.2mum number average particle size. This polymer is dissolved or dispersed in the polymerizable monomer and the resulting polymerizable monomer compsn. is suspension-polymerized to obtain a toner not lowering image density, having a sharp electric charge distribution and not causing fogging at the time of using as a toner. Since the dispersibility of the carbon black is improved, satisfactorily high image density is obtd.

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, a polymerized toner has been produced by dispersing carbon black in a polymerizable monomer and then suspending and polymerizing it in a dispersion medium that is substantially incompatible with the polymerizable monomer. There is a law.

[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 the carbon black in the 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 suspension polymerization in Sufficient image density cannot be obtained.

- [Means for Solving the Problems] The present inventor has arrived at the present invention as a result of intensive 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 by suspension polymerization from a polymerizable monomer composition containing a polymerizable monomer (A), carbon black (B), and a polymer (C). Suspension polymerization of a polymerizable monomer composition obtained by melt-kneading a polymer and finely dispersing carbon black to a number average dispersed particle size of 0.2 μm or less in a polymerizable monomer. This is a unique method for producing polymerized toner.

In the present invention, carbon black (B) that has a specific surface area of 80+112/g or more as determined by BET can be used. Particularly preferably a specific surface area of 130n+
278 or more are used.

Surface-treated carbon black can also be used. Examples of surface treatments include polymer grafting, surface oxidation treatment, and surface adsorption treatment.

In the present invention, the polymer <C> is a polymer consisting of a styrene monomer, a (meth)acrylic monomer and/or a maleic acid monomer, and a polymer consisting of an amino group-containing monomer. can be mentioned.

Examples of styrenic monomers include styrene and styrene-substituted monomers (
Alkylstyrenes such as α-methylstyrene, o-,
it- or p-methylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, p-n-butylstyrene, p-tert-butylstyrene, p-n-hexylstyrene, p-n-octylstyrene), etc. can be mentioned.

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 1-butyl (meth)acrylate, n-octyl (meth)acrylate, 2-ethylhexyl ( meth)acrylate, lauryl (meth)acrylate and stearyl (meth)acrylate],
Examples include hydroxyl group-containing (meth)acrylates [hydroxylethyl (meth)acrylate, etc.]. Among these, methyl (meth)acrylate, ethyl (meth)acrylate, n- or i
-Butyl (meth)acrylate, 2-ethylhexyl (
meth)acrylates, 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 (butyl 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.],
Amino group-containing (meth)acrylamide [N,N-dimethylacrylamide and the like can be mentioned.

The polymer (C) can also contain other monomers as copolymerization components. Other monomers include styrene monomers, (meth)acrylic monomers, maleic acid monomers,
Amino group-containing monomers, nitrile group-containing (meth)acrylic compounds (acrylonitrile, etc.), (meth)acrylic compounds, vinyl esters, vinyl propionate, etc.), aliphatic hydrocarbon vinyl monomers (butadiene, etc.), j.lyl compounds (acrylonitrile, methacrylonitrile, etc.), vinyl ethers (vinyl methyl ether, vinyl ethyl ether, vinyl isobutyl ether, etc.)
, vinyl ketones (vinyl methyl lactone, vinyl hexyl ketone), N-vinyl compounds (tovinylvirol, N-vinylcarbazole, N-vinylindole,
tovinylpyrrolidone, etc.), vinyl halides (vinyl chloride, etc.), and the like.

In order to obtain a polymer with a higher molecular weight, a monomer having at least two polymerizable double bonds may be copolymerized. Examples of the polyfunctional monomer include di- or polyvinyl compounds (divinylbenzene, divinyltoluene, ethylene glycol diacrylate, 1°6-hexanediol diacrylate, trimethylolpropane triacrylate, etc.).

When the polymer (C) is a copolymer 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 the maleic acid monomer is usually 100:5 to 100, preferably 10
0:10-50. If the content of the (meth)acrylic monomer and/or maleic acid monomer is less than 5, the minimum fixing temperature will be high and it will not be practical as a toner, and if it exceeds 100, the glass transition point will be low and the toner will have poor storage stability. becomes worse.

When the polymer (C) consists of an amine group-containing monomer, the weight ratio of the amino group-containing monomer to other monomers is usually
100:O-900, preferably 100:100-40
It is 0.

The amount of each monomer in the total monomers is based on the weight of the total monomers when starting with styrene monomers, (meth)acrylic monomers, and/or maleic acid monomers. Styrenic monomer content is usually 45-95%, preferably 60-90%
, (meth)acrylic monomer and/or maleic acid type R
Other monomers are usually 10% or less, preferably 5% or less, and polyfunctional monomers are usually 3% or less, preferably 1% or less. It is.

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 0 to 90%, preferably 50 to 80%
%, polyfunctional monomer is usually 3% or less, preferably 1% or less.

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

The number average molecular weight of the polymer (C) is usually 1.000 to 400
,000, preferably 1,500 to 30,000 or 70,000 to 30o, particularly preferably 2
, 500 to 20,000.

The molecular weight distribution of the polymer (C) may exhibit either a single peak or two or more peaks.

The polymer (C) may have a crosslinked structure.

When melt-kneading carbon black (B) and polymer (C), magnetic powder (ferromagnetic metal powder such as iron, cobalt, nickel, etc. or compound such as magnetite, hematite, ferrite, etc.) may be added to polymer (C) as necessary. ) 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.

In addition, the polymer (C) also has anti-offset, improved fluidity,
A low molecular weight polyolefin wax can be uniformly dispersed and used for the purpose of improving fixing properties. Examples of this low molecular weight polyolefin wax are (a): polyethylene, polypropylene, ethylene-α
Olefin (carbon number 3 to 8) copolymer (e.g. ethylene 50% by weight or more, especially 70% by weight or more) (0)
: Maleic acid derivatives (a) (maleic anhydride, maleic acid dimethyl ester, maleic acid diethyl ester, maleic acid di-2-ethylhexyl ester, etc.)
Adduct, (c) = oxide of (i), (d): ethylenically unsaturated carboxylic acid [(meth)acrylic acid, itaconic acid, etc. and/or its ester [alkyl (C7-Cl8) ester, etc.] and ethylenically unsaturated hydrocarbons (ethylene, propylene, butene-1, etc.)
Examples include copolymers with and mixtures of two or more of these.

Among the above-mentioned low molecular weight polyolefin waxes, (a) is a high molecular weight polyolefin (the molecular weight is usually io or oo).

~2,000,000) by thermally degrading (pyrolysis) 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. (C) can be obtained by oxidizing a low molecular weight polyolefin wax with oxygen or an oxygen-containing gas (air), or by oxidizing it with ozone-containing oxygen or an ozone-containing gas (air).

The oxide value is usually 100 or less, preferably 50 or less. (d) is obtained by copolymerization of an ethylenically unsaturated carboxylic acid and/or its alkyl ester (Ct to Cl8) and an ethylenically unsaturated hydrocarbon. The amount of ethylenically unsaturated carboxylic acid and/or its alkyl ester is usually 30% or less, preferably 20% or less, based on weight.

The molecular weight of the polyolefin wax was measured using GPC (gel permeation chromatography) as a solvent.
It can be measured using dichlorobenzene at 135°C.

The low molecular weight polyolefin wax can be uniformly dispersed in the polymer by melt-kneading 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 such as charge control agents (metal complexes, nigrosine, etc.), lubricants (bolite, dorafluoroethylene, fatty acids or metal salts, or amides, etc.)) 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 black (B) during melt-kneading is the same as that of the polymer (C
), preferably 20 to 45%.

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 (B), polymer (C), and other components if necessary, a general kneader such as a twin-screw extruder, three-roll mill, or lab blast 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 (A) consists of a styrene monomer, a (meth)acrylic monomer and/or a maleic acid monomer, and an amino group-containing monomer. Things can be mentioned.

The styrene monomer, (meth)acrylic monomer, maleic acid monomer and amino group-containing monomer are the same as the monomers described in the section of polymer (C). , preferred ones are also the same.

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

A monomer 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 polymer (C).

In the case where the polymerizable monomer (A) 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
100:5-100, preferably 100:t.

~50. If the content of the (meth)acrylic monomer and/or maleic acid monomer is less than 5, the minimum fixing temperature will be high and it will not be practical as a toner, and if it exceeds 100, the glass transition point will be low and the toner will have poor shelf life. Deteriorate.

When the polymerizable monomer (A) consists of an amino group-containing monomer, the weight ratio of the amino group-containing monomer to other monomers is usually 100:100 to 900, preferably 100:1.
50-400.

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 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 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 50%, preferably 20 to 40%, based on the weight of all monomers. %,
Other monomers are usually 50-90%, preferably 60-80%
%, polyfunctional monomer is usually 1% or less, preferably 0.5
% or less.

When the amount of polyfunctional monomer exceeds 1%, the MF increases,
It cannot withstand practical use as a toner.

The amount of carbon black (B) is 5 to 15%, preferably 7 to 10%, based on the total polymerizable monomer composition.

The amount of polymer (C) is usually 55% or less, preferably 45% or less, particularly preferably 30% or less, based on the weight of the total polymerizable monomer composition. %
If it exceeds this, the viscosity of the polymerizable monomer composition will increase and the dispersed particle size during suspension polymerization will become coarse.

The amount of magnetic powder is usually 0 to 50% of the total polymerizable monomer composition.
It is.

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

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

In suspension polymerizing the polymerizable monomer, the radical polymerization initiator used for suspension polymerization of the polymerizable monomer composition is an oil-soluble peroxide (benzoyl peroxide, lauroyl peroxide, etc.) and/or Azo polymerization initiators (2,2'-azobisisobutyronitrile, 2,2'-azobis(2,4-dimethylvaleronitrile, etc.) are used alone or in combination of two or more. Also, A chain transfer agent can be used if necessary in the suspension polymerization of the polymerizable monomer composition. Examples of the chain transfer agent include mercaptan compounds, halogen compounds, and α-methylstyrene dimer.

The amount of the polymerization catalyst used is usually O01 to 10%, preferably 0.3 to 5%, based on the weight of the total polymerizable monomer composition.

The amount of chain transfer agent is usually less than 5%, preferably less than 1%, based on the total weight of the entire polymerizable monomer composition.

Such a polymerizable monomer composition is dispersed and suspended in a bell-shaped dispersion medium that contains a dispersion stabilizer and is substantially incompatible with the polymerizable monomer composition.

Water is an example of a liquid dispersion medium that is substantially incompatible with the above monomer composition.

Examples of dispersion stabilizers include water-soluble polymers (gelatin, gum tragacanth, starch, methylcellulose, hydroxyethylcellulose, carboxymethylcellulose, polyvinyl alcohol, polyvinylpyrrolidone, polyacrylate, etc.), poorly soluble inorganic compounds in the form of fine powder ( barium sulfate, calcium sulfate, barium carbonate, calcium carbonate, magnesium carbonate, calcium phosphate, talc, bentonite, diatomaceous earth, clay, etc.).

Additionally, a surfactant and an anti-emulsifying agent may be used if necessary. Examples of the surfactant include sulfonate (sodium dodecylbenzenesulfonate, sodium arylalkylpolyether sulfonate, 3,3-disulfone diphenyl urea-4,4-diazo-bis-amino-
Sodium 8-naph I--6-sulfonate, ortho-carboxybenzene-azo-dimethylaniline, 2,
2,5,5-tetramethyl-triphenylmethane-4,
Sodium 4-diazo-bis-β-naphthol disulfonate, etc.), sulfate ester salts (sodium tetradecyl sulfate, sodium pentadecyl sulfate, sodium octyl sulfate, etc.), fatty acid salts (sodium oleate, sodium laurate, sodium capric acid, sodium caprylate, sodium caproate, potassium stearate, calcium oleate, etc.).

Examples of the anti-emulsifying agent include water-soluble inorganic salts (such as sodium chloride).

The amount of dispersion stabilizer is usually 0.01 to 10% by weight of water.
%, preferably 0.1 to 5%.

The amount of surfactant used is usually 0.01 based on the weight of water.
~1%, and the amount of anti-emulsifying agent used is usually 0.1-10% based on the weight of water.

The concentration of the polymerizable monomer composition in the dispersion is usually 5 to 5% by weight, preferably 10 to 45% by weight, particularly preferably 20% by weight.
It is 0 to 40% by weight.

There are two methods for dispersing and suspending the polymerizable monomer composition in a dispersion medium: mechanical stirring (for example, using a homomixer, homogenizer, etc.) and ultrasonic waves. good.

As a typical dispersion method, when a homomixer is used, stirring conditions are such that the stirring rotational speed is usually 1000 rp+n≦. The temperature is usually 10-50°C. Stirring time is usually 1~
It is 30 minutes.

The dispersed polymerizable monomer composition is usually classified. It is best to use a classifier for classification. As the classifier, it is preferable to use a so-called wet classifier that utilizes the difference in sedimentation speed of particles in a liquid. Wet classifiers include sedimentation tank type, mechanical classifier type, hydraulic classifier type, hydrocyclone type, centrifugal classifier type, and inertial classifier type.

Preferred are a hydraulic classifier system, a hydrocyclone system, a centrifugal classifier system, and an inertial classifier system, and particularly preferred are a hydrocyclone system, a centrifugal classifier system, and an inertial classifier system.

The average particle size of a toner suitably used as a polymerized toner is usually 30 μm or less, preferably 2 to 20 μm. Therefore, it is preferable to classify the particles according to this particle size. Compared to these particle sizes, the sedimentation tank classifier and mechanical classifier can classify large particle sizes, and although it is difficult to use them alone in the present invention, which aims at toner, they can be used in combination.

Super Chron (manufactured by Oishi Kikai Seisakusho) In TR-10 cyclone, the treatment per cyclone is at an inlet pressure of 3 to 4 kg/cm2.
This makes it possible to process 8 liters/minute. In addition, Decanting Centrifuge (manufactured by Mitsubishi Kakoki) KVZ2O
Type 5 is used under the conditions of a flow rate of 0.5 to 1T+1''/hour and a centrifugal effect of 500 G or less (2114 rpm or less). Furthermore, a Humboldt centrifuge (manufactured by Kotobuki Giken) is used at 500 G or less.

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

Suspension 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 toner is washed with water, filtered, and dried under reduced pressure to obtain a spherical polymerized toner having an average particle size of 3 to 20 μm.

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 toner will be hard to beat and cannot be used practically as a toner.

Molecular weight distribution of polymer in toner [The ratio of weight average molecular weight to number average molecular weight (Mw/m) is usually 1
0 or more, preferably 20 or more as a binder for electrophotographic toner. If the molecular weight distribution is less than 10, the balance between the temperature at which offset occurs (HO) and the minimum fixing temperature (MF) will be poor.

The weight average molecular weight of the tetrahydrofuran (TIIF) soluble portion of the polymer in the toner, such as styrene/acrylic acid ester or styrene/maleic ester, is usually 1 x 10
3 to 1×106, preferably 5×103 to 1×105. When the molecular weight is less than 1x103, the glass transition point (Tg
) decreases, blocking characteristics worsen, and 1x10
When using a heat roller to fix an electrostatic latent image visualized with toner, the lower limit temperature for fixing (6)
becomes too high.

The molecular weight can be expressed as a weight average by gel permeation (GPC) using T)IF as a solvent and standard polystyrene.

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

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

Synthesis Example 1 720 parts of styrene, 1 part of 2-ethylhexyl acrylate
A mixed solution of 90 parts of methyl methacrylate, 90 parts of methyl methacrylate, and 6.5 parts of divinylbenzene [referred to as (solution 1-1)]
, 2. A solution of 8.5 parts of 2'-azobisisobutyronitrile and 250 parts of toluene [(Solution 1-2) and 2 parts of 2'-azobisisobutyronitrile and 55 parts of toluene A solution called (solution 1-3) was 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 the toluene was refluxed for 4 hours (
Solution 1-1) and (solution 1-2) were added dropwise, and then 2
Refluxed for an hour. Thereafter, (solution 1-3) was added twice every hour to complete the polymerization. The solvent is distilled off and the glass transition point is 6.
A vinyl polymer having a number average molecular weight of 300,000 and a weight average molecular weight of 300,000 was obtained at 1°C. ``This polymer is referred to as Polymer (C-1).

Example 1 200 parts of carbon black MA100 (manufactured by Mitsubishi Kasei),
After mixing 800 parts of polymer (C-1) into powder, use a lab blast mill at 150°C and at a rotation speed of 10~? Orp
The mixture was melt-kneaded for 30 minutes at m. When the cross section was observed with an electron microscope, carbon black was 0.02 μm to 0.2 μm.
It has a dispersed particle size distribution of m and its number average dispersed particle size is 0.
It was removed at 0.04 μm. The above polymer in which carbon black is finely dispersed is referred to as Polymer (C-2).

After powder-mixing 875 parts of polymer (C-2), 100 parts of Viscole ejop c (low molecular weight polypropylene manufactured by Sanyo Chemical Industries) and 25 parts of Bontron N-10 (manufactured by Orient Chemical Co., Ltd.), the mixture was heated at 140° C. in a lab blast mill. The mixture was melt-kneaded for 30 minutes at a rotational speed of 10 to 70 rpm+. The above polymer in which carbon black and Viscoel 660P are finely dispersed is referred to as Polymer (C-3).

504 parts of styrene, 7 parts of 2-ethylhexyl acrylate
6 parts, 1-120 parts of methyl methacrylate, 2,2'-
20 parts of azobisisobutyronitrile and 10 parts of t-lauryl mercaptan were mixed, and 300 parts of polymer (C-2) was dissolved and dispersed. This dispersion was mixed into a polymerizable monomer composition (
D-1). The above polymerizable monomer composition (D-1)
1000 parts of water containing 1.5% of tertiary calcium phosphate and 0.015% of sodium alkylbenzenesulfonate
In addition to 0 parts, add 1001000 parts in a homomixer at 30°C.
The monomer composition was dispersed by stirring for 1 minute.

Next, the dispersed monomer composition was classified. The classification conditions were to use a super cyclone (manufactured by Anaishi Kikai Seisakusho), with an inlet pressure of 3 to 4 kg/cm2, a top pressure of OKg/am2, and a M
Idle pressure OKg/cm2, Bottom pressure 0.3~
It was adjusted to 0.5Kg/cm2. Coarse particles (volume average diameter of about 10 μm) coming out of the bottom were sent back to the dispersion step to be atomized again.

Next, the classified dispersion of the monomer composition was heated under a nitrogen atmosphere while stirring at low speed with a paddle type stirrer at 60°C for 5 hours, at 75°C for 2 hours, and further at 95°C for 2 hours. Polymerization was carried out.

The aqueous medium containing the polymerized toner was cooled, neutralized with an aqueous hydrochloric acid solution, washed with water, dehydrated, and dried to obtain a polymerized toner.

A polymerized toner having a particle size of 1 μm to 15 μm (average particle size 81-t) as measured by a Coulter counter was obtained with a yield of 98%.

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 Example 10 When preparing the polymer (C-3), carbon black MA100 (manufactured by Mitsubishi Kasei), the polymer (C-2'
), Viscol 660P (low molecular weight polypropylene manufactured by Sanyo Chemical Industries) and Bontron N-10 (manufactured by Orient Chemical Industries) were simultaneously powder-mixed, and then mixed in a lab blast mill at 140°C and at a rotation speed of 10~? A polymerized toner was obtained in the same manner as in Example 1, except that the mixture was melt-kneaded for 50 minutes using Orpm.

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 3 Polyvinyl alcohol (Saponification degree 8
A polymerized toner was obtained in the same manner as in Example 1, except that 2500 parts of water containing 8% and 0.3% polymerization degree was used.

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.

Comparative Example 1 Styrene 504 instead of polymerizable monomer composition (D-1)
parts, 76 parts of 2-ethylhexyl acrylate, 120 parts of methyl methacrylate, 20 parts of 2,2'-azobisisobutyronitrile, and 10 parts of t-lauryl mercaptan.
To this, carbon black MA100 (manufactured by Mitsubishi Kasei), polymer (C-1), and Viscol 660P (
After adding low molecular weight polypropylene (manufactured by Sanyo Chemical Industries) and Bontron N-10 (manufactured by Orient Chemical),
Polymerizable monomer composition (D-2) prepared by stirring for 100010000 rpm in a homomixer at °C
A polymerized toner was obtained in the same manner as in Example 1 except that .

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] According to 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 diameter of carbon black in a polymerizable monomer is reduced by a small amount, and the resulting polymer is suspension polymerized in a dispersion medium that is substantially incompatible with the polymerizable monomer. By eliminating deviations in the carbon black content of each particle, we produce a polymerized toner that, when used as a toner, has a sharp charge distribution and no fogging, and provides sufficiently high image density due to improved dispersibility of carbon black. It becomes possible to do so.

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.

Claims (1)

[Claims] 1. A method for producing a polymerized toner by suspension polymerization from a polymerizable monomer composition containing a polymerizable monomer (A), carbon black (B), and a polymer (C) , a polymerizable monomer composition in which carbon black and a polymer are melt-kneaded and carbon black is finely dispersed to a number average dispersed particle size of 0.2 μm or less is dissolved and dispersed in a polymerizable monomer. A method for producing a polymerized toner characterized by polymerization. 2. The production method according to claim 1, wherein the polymerizable monomer (A) comprises a styrene monomer, a (meth)acrylic monomer, and/or a maleic acid monomer. 3. The manufacturing method according to claim 1, wherein the polymerizable monomer (A) comprises a polymerizable monomer having an amino group. 4. The specific surface area of carbon black (B) is 130m^2
The manufacturing method according to any one of claims 1 to 3, wherein the amount is at least /g. 5. Any one of claims 1 to 4, wherein the polymer (C) is a copolymer of a styrene monomer, a (meth)acrylic monomer, and/or a maleic acid monomer. Manufacturing method described. 6. The production method according to any one of claims 1 to 4, wherein the polymer (C) is a (co)polymer of monomers comprising a polymerizable monomer having an amino group. 7. The production method according to any one of claims 1 to 6, wherein the polymer (C) contains a monomer having at least two polymerizable double bonds. 8. The manufacturing method according to any one of claims 1 to 7, wherein the mixing weight ratio of carbon black (B) and polymer (C) during melt-kneading is 10 to 100 parts by weight of carbon black to 100 parts by weight of polymer. .