JPH0197967A - Manufacture of electrophotographic toner - Google Patents

Abstract

PURPOSE:To enhance fixability and offset resistance and to prevent fog by executing a specified combination of the emulsion polymerization and suspension polymerization methods and using as a specified suspension dispersion stabilizer a specified surfactant specified in concentration during polymerization. CONSTITUTION:The electrophotographic toner always stable in fixability and offset resistance and capable of forming a fog-free good image can be obtained by emulsion polymerizing a radically polymerizable monomer capable of dissolving its polymer, dissolving the obtained polymer particles in the monomer in a prescribed proportion, and dispersing a colorant into it to produce a solution uniform in composition, suspending this solution in water, and suspension polymerizing it in the presence of the surfactant as the suspension emulsion stabilizer in a concentration less than a critical micell concentration together with a radical polymerization initiator in a solubility in water of <=0.05g/100cc at 25 deg.C. Thus, the title toner giving good image, stable fixability and offset resistance, is obtd.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention provides a toner for electrophotography that has an excellent combination of fixing properties and anti-offset properties, and has a particle size suitable for electrophotographic development and a uniform particle size distribution. Regarding the manufacturing method of
More specifically, the toner is produced by performing a specific combination of an emulsion polymerization method and a suspension polymerization method, and using a specific suspension dispersion stabilizer concentration and a specific surfactant during the suspension polymerization. Regarding the method.

[Prior art]

Conventionally, in the field of electrophotography, toner is used for the purpose of visualizing electrostatic images. These toner particles are made of a composition comprising a colorant and, if necessary, other additives such as a charge control agent, mixed in a resin medium to a certain particle size range, for example, 1 to 30.
The resin medium is a styrene resin with the desired electrodetection properties and binding properties, and the coloring agent is carbon black or other organic Color pigments of organic or inorganic type are used.

The most typical manufacturing method for electrophotographic toners consists of the steps of melt-kneading the above-mentioned resin medium and colorant, cooling and pulverizing this kneaded composition, and classifying the pulverized product to make the particle size within a certain range. However, the yield of toner obtained by this pulverization and classification is low, and a large amount of equipment is required for these operations, which makes the manufacturing cost of toner extremely high. Furthermore, since the shape of the resulting particles is irregular, the fluidity of the toner is generally low and blocking is likely to occur.

Conventionally, many proposals such as emulsion polymerization method, suspension polymerization method, etc. have been accepted regarding the direct production of toner through the polymerization process of resin for toner. A typical method is to dissolve a polymerization initiator soluble in a water-insoluble monomer, add additives such as a coloring agent, and then mix this composition with a suitable dispersant, such as a water-soluble polymer, Colored polymer particles are produced by suspending the suspension in an aqueous solution containing an inorganic powder, a surfactant, etc. by high-speed shear stirring, and polymerizing the suspension.

Generally, resins with large molecular weights have poor fixing properties, and resins with small molecular weights tend to offset easily. Many proposals have already been made to improve the fixing properties and anti-offset properties of toner particles obtained by suspension polymerization, such as (2) a method of lowering the molecular weight using a chain transfer agent.

■ Partial crosslinking method.

■ Method of mixing polyolefin wax etc.

■ A method in which polymer resin particles produced by suspension polymerization and monomers are suspended and polymerized.

etc. are known.

[Problem that the invention seeks to solve]

However, the suspension polymerization method has the following problems.

In the above-mentioned means for improving fixing properties and offset resistance, (2) lowering the molecular weight too much improves fixing properties but tends to cause offset, (3) is effective in improving offset resistance, but
The appropriate amount range of poly-lipid-sensitive monomer is narrow and difficult to adjust. If it is too small, offset resistance cannot be obtained, and if it is too large, fixing performance is poor.

In case (1), the compatibility between the polyolefin wax and the vinyl monomer (polymer) is poor (good dispersion cannot be obtained, and sufficient anti-offset effect cannot be obtained, and the electrophotographic properties may be adversely affected).

In case (2), the molecular weight of the resin obtained by the suspension polymerization in the first stage is still lower than that obtained by emulsion polymerization, and the offset resistance is still not fully satisfactory, and the polymerized polymer resin is filtered and washed. Not only is it necessary to go through a complicated process of removing the dispersant by washing, drying it, and then mixing it with monomers and carrying out suspension polymerization, but if washing is insufficient, the hygroscopicity of the dispersant can lead to high humidity. The disadvantage is that the charging characteristics at the bottom become unstable.

In addition, in the suspension polymerization method, the particle size of the final toner is determined by the state of suspension of the monomer composition in water, and the particle size distribution is determined by adding the monomer composition into water or stirring it. Depending on the situation, it is very broad and it is difficult to obtain particles with a single particle size.

Furthermore, in general, in this suspension polymerization method, the
It is difficult to obtain particles with a particle size of 1 to 30 μm that are useful as developer toners. Of course, it is possible to make the particle size of the produced toner finer by increasing the amount of dispersant blended, but in this case, the dispersant is contained in the toner and the toner tends to be sensitive to humidity. etc., which tends to cause deterioration of electrophotographic characteristics. In order to prevent this, special post-processing operations are required and the number of steps is large, making it impractical.

In particular, a problem with toner produced by the suspension polymerization method is that it is difficult to avoid particle size asymmetry, especially the incorporation of fine particles at a certain ratio. Particles consisting solely of polymers that do not contain
Since the characteristics are different from toner particles, even if a small amount is mixed in, it will cause toner scattering and fogging during development.Also, even if these fine particles can be removed, the resulting toner particles will have a different composition than the initial composition. will be significantly different, and not only will the desired properties not be obtained, but the yield will decrease, resulting in higher costs.

Therefore, the object of the present invention is to solve the above problems at the same time,
The composition of high molecular weight resin that contributes to offset resistance and low molecular weight resin that contributes to fixing properties is uniform and constant for each toner particle, and the fine particle size and uniform particle size distribution are suitable for developing toner. As a result, it is possible to always obtain stable fixing properties and anti-offset properties, and also to provide good images without fogging, and it is possible to directly produce toner particles through a suspension polymerization process. The goal is to provide a method.

[Means for solving problems]

According to the present invention, high molecular weight resin particles obtained by emulsion polymerization of a radically polymerizable monomer having a property that the resulting polymer dissolves in the monomer are dissolved in the monomer at a constant ratio. and disperse the colorant to produce a solution of homogeneous composition, and this solution is suspended in water and treated as a suspension dispersion stabilizer in the presence of a surfactant at a concentration lower than the critical micelle concentration.
There is provided a method for producing a developing toner characterized by carrying out suspension polymerization in the presence of a radical polymerization initiator having a solubility in water of 0.05 g/100 cc or less at 5°C.

[Effect]

In the present invention, a radically polymerizable monomer having a property that the resulting polymer dissolves in the monomer is first used. By subjecting this radically polymerizable monomer to emulsion polymerization, a blended resin component having a high molecular weight sufficient to impart sufficient anti-offset properties to the toner can be obtained.

One of the important features of the present invention is that the high molecular weight resin particles obtained by this emulsion polymerization are dissolved in the above-mentioned monomers in a fixed quantitative ratio to form a solution with a uniform composition. Generally, the particle size of resin particles obtained by emulsion polymerization is on the order of 0.01 to 1 μm, and the particle size for electrophotography is 1 to 30 μm.
The particle size is very small in the μm range.

Therefore, when monomers are polymerized using individual particles by emulsion polymerization as seeds and grown to the above-mentioned toner particle size, the content ratio of the emulsion polymerized resin, that is, the high molecular weight resin becomes small, and sufficient durability is required. This means that the offset property cannot be changed. Of course, if one suspended particle contains emulsion polymerized particles in a proportion or number commensurate with a predetermined blending ratio, such drawbacks may be overcome, but in this case, individual The composition ratio of the emulsion polymerized particles and the monomer contained varies for each suspended particle, and therefore the combination of fixing properties and anti-offset properties varies for each toner particle.

In the present invention, by dissolving the emulsion polymerized resin particles in the monomer and homogenizing the whole, the composition of the suspended particles becomes constant for each particle, and excellent combination properties can be obtained.

However, even with the above method, the particle size of the produced toner exhibits a broad distribution. Therefore, the present invention uses a radical polymerization initiator whose solubility in water at 25° C. is 0.05 g/10'Oc c or less in the presence of a surfactant at a concentration lower than the critical micelle concentration as a suspension dispersion stabilizer for suspension polymerization. The above problem was solved by conducting the test in the presence of.

The principle is shown below.

In the suspension polymerization method, suspended particles are dispersed in water using a suspension dispersion stabilizer, and polymerization is performed in the presence of a radical polymerization initiator dissolved in the suspended particles. As suspension stabilizers, inorganic fine powders, water-soluble polymeric protective colloids, surfactants, etc. are known, but all of these have advantages and disadvantages depending on their polymerization.

That is, inorganic fine powders and protective colloids are not yet fully satisfactory as suspension stabilizers, and the resulting resin particles tend to be coarse in particle size and have a very broad particle size distribution. On the other hand, although surfactants have excellent suspension stability, they cannot avoid the tendency to emulsify some of the suspended particles, resulting in the mixing of fine-sized emulsion polymer particles into the suspension polymer particles. I can't escape it. In the present invention, the use of a surfactant is indispensable from the viewpoint of controlling the particle size of the suspended polymer particles to a level suitable for the toner and uniformizing the particle size distribution.

However, from the standpoint of preventing emulsion polymerization contamination, the first condition is to use the surfactant at a concentration lower than the critical micelle concentration. Surfactants are ionized into long chain ions (anions) and counter ions when the concentration is small enough, but when the concentration reaches a certain level, that is, the critical micelle concentration, the long chain ions aggregate. , which has the property of forming micelles and becoming colloidal ions. The present invention attempts to prevent the generation of colloidal ions by using a surfactant at a concentration lower than the critical micelle concentration.

According to the research conducted by the present inventors, using a surfactant at a concentration lower than the critical micelle concentration during suspension polymerization is insufficient to avoid contamination with emulsion polymerization particles having a fine particle size. Understood. In order to completely prevent the contamination of emulsion polymer particles, the solubility in water at 25°C is 0.05.
The second essential condition is to use a radical polymerization initiator of g/100 cc or less.

In the present invention, the reason why contamination of emulsion polymer particles is prevented by using the above-mentioned specific radical polymerization initiator is considered to be as follows. That is, in a suspension polymerization system, there are monomers dissolved in water to varying degrees.

The monomer dissolved in water is polymerized by a radical polymerization initiator dissolved in water, and the generated polymer radical becomes a nucleus, which absorbs the monomer dissolved in water and grows to the size of emulsion polymerized particles. This seems to be the case. In contrast, according to the present invention, by controlling the solubility of the radical polymerization initiator in water to be below the above-mentioned reference value, the initiation of polymerization of the monomer dissolved in water is suppressed, and the generation of fine polymer particles is suppressed. It seems that

In the present invention, the monomers used are radically polymerizable, and the resulting polymer has the fixing properties and electrodetection properties required for toners, and monomers having ethylenic unsaturation are used. One or a combination of two or more of these substances may be used subject to the limitations set forth above. Suitable examples of such monomers include monovinyl aromatic monomers or combinations thereof with acrylic monomers, vinyl ester monomers, vinyl ether monomers, diolefin monomers, and monoolefin monomers. Quantities, etc.

As a monovinyl aromatic monomer, R1 is a hydrogen atom, a lower alkyl group, or a halogen atom, and R2 is a hydrogen atom, a lower alkyl group, a halogen atom, an alkoxy group, an amino group, a nitro group, or a vinyl group. or a monovinyl aromatic hydrocarbon which is a carboxy group, such as styrene α-chlorostyrene, 0-1m-1p
-, chlorostyrene, p-ethylstyrene, sodium styrene sulfonate, and divinylbenzene singly or in combination of two or more, and as the other monomers mentioned above, the following may be mentioned, respectively.

Formula % Formula % (2) In the formula, R3 is a hydrogen atom or a lower alkyl group, and R4 is a hydrogen atom, a hydrocarbon group having up to 12 carbon atoms, a hydroxyalkyl group, a vinyl ester group, or an aminoalkyl group. Monomers such as acrylic acid, methacrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, phenyl acrylate, 2-methacrylate
-ethylhexyl, ethyl β-hydroxyacrylate,
γ-hydroxypropyl acrylate, δ-hydroxybutyl acrylate, β-hydroxyethyl methacrylate,
T-aminopropyl acrylate, γ-N, N-diethylaminopropyl acrylate, ethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, etc.

Vinyl esters of the formula % formula % in which R3 is a hydrogen atom or a lower alkyl group, such as vinyl formate, vinyl acetate, vinyl propionate, etc.

Vinyl ethers such as vinyl methyl ether, vinyl ethyl ether, vinyl-n-butyl ether, vinyl phenyl ether, vinyl cyclohexyl ether, etc., where R6 is a monovalent hydrocarbon group having up to 12 carbon atoms.

Diolefins, particularly butadiene, isoprene, chloroprene, etc., of formula % formula % (5) in which each of R7, R11, and R1 is a hydrogen atom, a lower alkyl group, or a halogen atom.

Formula %Formula % (6) In the formula, each of R9° and Ro is a hydrogen atom or a lower alkyl group, monoolefins, especially ethylene, propylene, isobutylene, butene-1, pentene-1,4-methylpentene -1st class.

A preferred monomer composition is 30 to 100% by weight of styrene, particularly 50 to 90% by weight, and 0 to 70% by weight of acrylic monomer.
% by weight, especially 1% to 50MN.

As the colorant, various pigments and dyes (hereinafter simply referred to as coloring pigments) for coloring the toner are used.

Suitable examples of colored pigments are:

Black pigment carbon black, acetylene black, lamp black, aniline black yellow pigment yellow lead, zinc yellow, cadmium yellow, yellow iron oxide mineral fast yellow, nickel titanium yellow, navel yellow, naphthol yellow S1 Hansa Yellow G1 Hansa Yellow 10G , Benzidine Yellow G1 Benzidine Yellow GR, Quinoline Yellow Lake, Permanent Yellow NCG.

Tartrazine rake.

Orange pigment red yellow lead, molybdenum orange, permanent orange GTR, pyrazolo orange, palkan orange, indanthrene brilliant orange RK1 benzidine orange G1 indanthrene brilliant orange GK.

Red pigment Red pigment Red Garla, Cadmium Red, Red Lead, Mercury Cadmium Sulfide, Permanent Red 4R, Lysole Red, Pyrazolone Red, Watching Red Calcium Salt, Lake Red D1 Brilliant Carmine 6B, Eosin Lake, Rhodamine Lake B1 Alizarin Lake, Brilliant Carmine 3 Purple Pigment Manganese purple, Fast Violet B1 Methyl Violet Lake.

Blue pigments navy blue, cobalt blue, alkali blue lake, Victoria blue lake, phthalocyanine blue, metal-free phthalocyanine blue, phthalocyanine blue partially chlorinated product, first sky blue, indanthremble-BG
.

Green pigment chrome green, chromium oxide, pigment green B,
Malachite Green Lake, Fanal Yellow Green G.

White pigments zinc white, titanium oxide, antimony white, zinc sulfide extender pigment pallite powder, barium carbonate, clay, silica, white carbon, talc, alumina white.

Conventionally, as magnetic material pigments, for example, triiron tetroxide (Fe,
04), iron sesquioxide (7-Fe, O,), zinc iron oxide (Z n FezOa ), iron yttrium oxide (
Y3 Fe50+z), cadmium oxide (Cd Fe
zO1), gadolinium oxide (Gd3Fes0.2),
Iron copper oxide (Cu Fe, O,), iron oxide complex (P b
Fe+z 0.9), iron nickel oxide (N i Fet
e), neodymium iron oxide (NdFe03), barium iron oxide (BaFe,,O,,), magnesium iron oxide (MgFez04), magnesium iron oxide (MnF
e, 04), lanthanum iron oxide (LaFeO3), iron powder (Fe), cobalt powder (Co), nickel powder (Ni), etc., and the present invention also uses fine powders of these known magnetic materials. Any one can be used.

In the present invention, in addition to the above-mentioned colorants, additive components that are desirable to be included in the toner can be blended into the polymerization system prior to polymerization.

For example, for use as a two-component pigment, charge control agents known per se, such as nigrosynpase (C15045), may be used.
, Oil Black (CI26150), Spiron Black, and other oil-soluble dyes, naphthenic acid metal salts, fatty metal soaps, fatty acid soaps, etc. can be blended. It can contain a mold release agent such as molecular weight polyethylene, low molecular weight polypropylene, various waxes, and silicone oil.

The emulsion polymerized resin particles used in the present invention are produced by subjecting the monomers described above to emulsion polymerization, which is known per se. Generally speaking, this resin particle is 0.01 to 1μ
m, in particular a particle size of 0.1 to 0.7 μm, and 200,000
It has a weight average molecular weight t (Mw) of 300,000 to 2,000,000.

Resin particles obtained by ordinary emulsion polymerization have a layer of a surfactant used as an emulsifier on their surfaces. The surfactant on the surface of the resin particles is removed by washing, extraction, or other means.

Particularly desirable emulsion polymerized resins for the purposes of the present invention are those obtained by so-called emulsifier-free emulsion polymerization.

Emulsifier-free emulsion polymerization refers to monomers that are dispersed or dissolved in an aqueous phase by using a water-soluble radical polymerization catalyst such as persulfate or redox without adding an emulsifier to a polymerization system containing water and monomers. The emulsion polymerized resin particles obtained by this method are particularly excellent in purity and electrical properties.

The above-mentioned emulsion polymerized resin particles and monomers are mixed in a fixed quantitative ratio and heated if desired to prepare a homogenized solution. The mixing ratio of high molecular weight resin particles and monomer varies depending on the required properties, but is 5:95 to 50:
50. In particular, it is preferable to mix at a weight ratio of 10:90 to 30:70.

If the blending ratio of emulsion polymerized particles is less than the above range, the offset resistance tends to be poor, while if it is greater than the above range, the fixing properties tend to be poor.

Compounding agents used in the developing toner, such as coloring agents, are preferably blended into this resin solution in an amount of 1 to 30% by weight, particularly 3 to 10% by weight, based on the total amount of resin and monomer. Similarly, the charge control agent is preferably blended in an amount of 10% by weight or less, particularly 1 to 5% by weight, and the mold release agent is blended in an amount of 10% by weight or less, particularly 1 to 5% by weight.

According to the present invention, the resin solution, the colorant, and, if necessary, the toner compounding agent are suspended and dispersed in water in the presence of a suspension dispersion stabilizer, and the resin solution and the colorant are suspended and dispersed in water in the presence of a radical polymerization initiator. polymerize in suspension.

In the suspension polymerization process, anionic surfactants are advantageously used as nasal surfactants used as suspension dispersion stabilizers. Suitable examples include, but are not limited to:

Fatty acid salts such as sodium oleate and castor oil potassium soap; Higher alcohol sulfate ester salts such as sodium lauryl sulfate and sodium cetyl sulfate; Alkylaryl sulfonates such as sodium dodecylbenzenesulfonate, sodium alkylnaphthalene sulfonate, β
- Sodium salts of naphthalene sulfonic acid formalin condensates, etc.; Nidialkyl sulfosuccinates, derivatives of naphthalene sulfonates; dialkyl phosphates; polyoxyethylene alkyl ether sulfates; polyoxyethylene alkyl ether sulfate triethanolamine, etc.;
Polyoxyethylene alkylphenol ether sulfates, etc.

As the suspension dispersion stabilizer, a water-insoluble inorganic powder may be used in combination with the above-mentioned surfactant.

This inorganic fine powder has a particle size of 0.001 to 5 μm.
are advantageously used. Suitable examples are tricalcium phosphate, talc, bentonite, kaolin, titanium oxide, alumina, zinc white, aluminum hydroxide, magnesium hydroxide, basic magnesium silicate, titanium hydroxide, ferric hydroxide, sulfuric acid. These include barium, silica, magnesium carbonate, calcium carbonate, etc.

The radical polymerization initiator is dissolved in the monomers mentioned above, and has a solubility in water of 0.05 g/100c at 25°C.
Must be less than or equal to c.

Hydroperoxides such as cumene hydroperoxide used in ordinary suspension polymerization and azobis compounds such as dimethyl-2゜2''-azobisisobutyrate do not meet this condition. Suitable examples are: , but are not limited to: lauryl peroxide, benzoyl peroxide, 2.2-azobis-2,4-dimethylvaleronitrile, 1-phenylethylazodiphenylmethane, 2.2'-azobis-2. 4,4.-1-
Limethylpentane etc.

The monomer is preferably used in an amount of 5 to 200 parts by weight, particularly 10 to 100 parts by weight, per 100 parts by weight of the aqueous medium.

The colorant may be blended in the amount contained in the toner resin, and is generally in the range of 1 to 30% by weight based on the amount of monomer charged. Further, when a magnetic material is used as a pigment, it is generally appropriate to use 5 to 300% by weight, particularly 10 to 250% by weight, based on the amount of monomer charged.

The amount of the radical initiator to be blended may be a so-called catalyst appropriate amount, and is generally preferably used in an amount of 0.1 to 10% by weight based on the monomers charged.

In addition, the surfactant can be used at a concentration lower than the critical micelle concentration,
-S is preferably added to an aqueous catalyst at a concentration of 50 to 100% of the critical micelle concentration.

In addition, when inorganic powder is used in combination, the concentration of inorganic powder in the aqueous catalyst is 0.01 to 50% by weight, especially 0.1 to 10.
It is best to use it in a way that makes it valuable.

The polymerization temperature is generally 40 to 100°C, particularly 50 to 90°C.
The temperature range is suitable, and although the polymerization time varies depending on the type of monomer, it is preferable to select a time for completing the polymerization from a range of 2 to 20 hours.

According to the present invention, by performing polymerization under the above conditions,
The particle size of the produced polymer particles, that is, toner particles, is 1 to 30μ.
It is easy to control m1 particularly within the range of 5 to 20 μm, the particle size distribution is extremely sharp, and the standard deviation thereof is generally 2 or more. The generated particles are separated from the reaction medium, subjected to purification operations such as washing if necessary, and dried to produce a toner product.

The colored particles for toner are sprinkled with carbon black, hydrophobic silica, etc., if necessary, to form a final toner.

〔Example〕

The invention will be explained more specifically with the following example.

Example 1 7 parts by weight of styrene and 3 parts by weight of n-butyl methacrylate were placed in a Yotsuro flask together with 90 parts by weight of water in which 0.1 part by weight of potassium persulfate was dissolved, and the mixture was heated at 100 rpm under a nitrogen stream.
Polymerization was carried out at 70° C. for 5 hours while stirring at . The molecular weight of the obtained polymer was Mw=650,000. This emulsion was centrifuged, the supernatant was discarded, and 32 parts by weight of styrene, 8 parts by weight of n-butyl methacrylate, 3 parts by weight of carbon black (PrinteL; manufactured by Degussa Corporation), and a charge control agent (Spiron Black TRH, manufactured by Hodogaya Chemical Co., Ltd.) were added. (manufactured by) 1
Part by weight, 3 parts by weight of 2.2'-azobis-2,4-dimethylvaleronitrile (V-65; manufactured by Wako Pure Chemical Industries, Ltd.) was added to O42.
χ Sodium dodecyl sulfate aqueous solution (critical micelle concentration 0.
In addition to 300 parts by weight of 26%), it was added to T. at 6000 rpm using an autohomogen mixer (manufactured by Tokushu Kika Kogyo).

Suspension and dispersion was performed by stirring for 10 minutes at a stirring speed of m.

This dispersion was put into a separable flask and heated for 60 minutes under a nitrogen stream.
Stirring was carried out at r, p, and m, and polymerization was carried out at 60° C. for a certain period of time. When the polymer was allowed to stand for a while, a precipitate formed and the supernatant liquid was transparent. The supernatant liquid was removed by decantation, and the precipitate was dried to obtain a toner.

When the particle size of this toner was measured using a Coulter counter, the average particle size was 10 .mu.m, and 90% of the particles were in the range of 5 to 15 .mu.m, indicating an extremely sharp particle size distribution. Further, the obtained toner had a Wardell practical sphericity of 0.95 to 1.0 and excellent fluidity.

Next, we investigated the molecular weight distribution of the resin that makes up the toner using GPC (gel permeation chromatography).
Polymer i! It had a molecular weight distribution with two peaks: (300,000 to 2,000,000) and low molecular weight (3,000 to 30,000).

This toner and a 150/300 mesh ferrite carrier (manufactured by Nippon Tetsuko Co., Ltd.) were mixed at a toner concentration of 4.5%, and the amount of charge was measured using a blow-off charge amount measuring device and found to be -18 μC/g.

The above two-component developer was applied to a copying machine manufactured by Sanda Kogyo Co., Ltd. DC-1001.
When a copying test was carried out, images with no fog and good tonality and blackness were obtained. When fixing was carried out at a fixing temperature of 170 degrees Celsius, the fixing rate was as good as 99%, and no offset phenomenon was observed when it was wrapped around the fixing roller. Further, even after 2000 copies were made continuously (the lifespan of the toner cartridge of DC-1001), no image deterioration was observed.

Comparative Example 1 Dimethyl 2,2°-azobisisobutyrate instead of 2.2″-azobis-2,4-dimethylvaleronitrile)
Example 1 except that (V-601; manufactured by Wako Pure Chemical Industries, Ltd.) was used.
Polymerization was carried out in the same manner as. When the polymer was left to stand for a while, a black precipitate was formed, but the supernatant liquid was cloudy with a large number of polymer particles of 1 μm or less that did not contain a colorant. The supernatant liquid was removed by decantation, and the precipitate was dried to obtain a toner.

When the particle size of this toner was measured using a Coulter counter, the average particle size was 11 μm. However, particles with a wide particle size distribution, ranging from 5 to 15 μm in diameter, have a diameter of 60 μm.
It was about %.

Next, when the molecular weight distribution of the resin constituting the toner was examined by GPC, it was found that the resin had a molecular weight distribution with two peaks at high molecular weight (300,000 to 2,000,000) and low molecular weight (3,000 to 30,000).

This toner and a 150/300 mesh ferrite carrier were mixed at a toner concentration of 4.5%, and the amount of charge was measured using a blow-off charge amount measuring device, which was -18 μC/g.
Met. The above two-component developer was used in a copying machine manufactured by Sanda Kogyo Co., Ltd.
A copy test was conducted with -1001. When fixing was carried out at a fixing temperature of 170 degrees Celsius, the fixing rate was as good as 99%, and no offset phenomenon was observed when it was wrapped around the fixing roller.

Although the initial image was not much different from Example 1.

In continuous copying, some fogging was observed after about the 1000th copy, and slight scattering of toner with large particle diameters was also observed.

Comparative Example 2 The concentration of sodium dodecyl sulfate aqueous solution was 0. Polymerization was carried out in the same manner as in Example 1 except that the amount was 5%. When the polymer was left to stand for a while, a black precipitate was formed, but the supernatant liquid was cloudy with a large number of polymer particles of 1 μm or less that did not contain a colorant. The supernatant liquid was removed by decantation, and the precipitate was dried to obtain a toner.

When the particle size of this toner was measured using a Coulter counter, the average particle size was 11 μm. However, the particle size distribution is wide, with particles in the 5-15 μm diameter range having a diameter of 70 μm.
It was about %.

Next, when the molecular weight distribution of the resin constituting the toner was examined by GPC, it was found that the resin had a molecular weight distribution with two peaks at high molecular weight (300,000 to 2,000,000) and low molecular weight (3,000 to 30,000).

This toner and 150/300 mesh ferrite carrier were mixed at a toner concentration of 4.5%, and the amount of charge was measured using a blow-off charge amount measuring device: 18 μC/
It was g. The above two-component developer was applied to a copier D manufactured by Sanda Kogyo Co., Ltd.
A copy test was conducted using C-1001. When fixing was carried out at a fixing temperature of 170 degrees Celsius, the fixing rate was as good as 99%, and no offset phenomenon was observed when it was wound around the fixing roller.

Although the initial image was not significantly different from Example 1, some fogging was observed from about the 1000th copy in continuous copying, and slight scattering of toner with large particle diameters was also observed.

Comparative Example 3 Styrene 39 parts by weight, n-butyl methacrylate) 111
i part by weight, 3 parts by weight of carbon black, 1 part by weight of charge control agent (spiron black TRH), 2°2''-azobis-
3 parts by weight of 2,4-dimethylvaleronitrile and 0.2χ sodium dodecyl sulfate aqueous solution were added to T and K.

Suspension and dispersion was performed by stirring for 10 minutes at a stirring speed of 6000 r, p, m using an autohomogen mixer.

This dispersion was put into a separable flask and heated for 60 minutes under a nitrogen stream.
Stirring was carried out at r, p, m, and polymerization was carried out at 60° C. for 6 hours. When the polymer was left to stand for a while, a precipitate formed and the supernatant liquid was transparent. The supernatant liquid was removed by decantation, and the precipitate was dried to obtain a toner.

When the particle size of this toner was measured using a Coulter counter, the average particle size was 10 .mu.m, and 90% of the particles were in the range of 5 to 15 .mu.m, indicating an extremely sharp particle size distribution. Further, the obtained toner had a Wardell practical sphericity of 0.95 to 1.0 and excellent fluidity.

Next, when the molecular weight distribution of the resin constituting the toner was examined by GPC, it was found that the resin had a molecular weight distribution with one peak at low molecular weights (3,000 to 30,000).

This toner and a 150/300 mesh ferrite carrier were mixed at a toner concentration of 4.5%, and the amount of charge was measured using a blow-off charge amount measuring device, which was -18 μC/g.
Met. The above two-component developer was used in a copying machine manufactured by Sanda Kogyo Co., Ltd.
-1001, an image with no fog and good tonality and blackness was obtained. Fixing temperature 17
When it was fixed at 0 degrees, the fixing rate was 99%, which was good. However, an off-cent phenomenon was observed, and wrapping around the fixing roller also occurred.

〔Effect of the invention〕

According to the present invention, the composition of the high molecular weight resin that contributes to offset resistance and the low molecular weight resin that contributes to fixing properties is uniform and constant for each toner particle, and the composition is fine particles suitable for a developing toner. It is an object of the present invention to provide a method for producing an electrophotographic toner that can obtain a particle size distribution that is uniform in diameter and, as a result, consistently stable fixing properties and anti-offset properties, and can provide good images without fogging. can.

Claims (6)

[Claims] (1) High molecular weight resin particles obtained by emulsion polymerization of a radically polymerizable monomer that has a property that the resulting polymer dissolves in the monomer are dissolved in the monomer at a certain ratio and colored. A solution having a uniform composition is prepared by dispersing the agent, and this solution is suspended in water, and in the presence of a surfactant at a concentration lower than the critical micelle concentration as a suspension dispersion stabilizer, the solubility in water at 25°C is 0. A method for producing an electrophotographic toner, which comprises subjecting monomers in suspended particles to suspension polymerization in the presence of a radical polymerization initiator of 0.05 g/100 cc or less. (2) The method according to claim 1, wherein the radically polymerizable monomer is a styrene monomer or a combination of a styrene monomer and an acrylic monomer. (3) The method according to claim 1, wherein the high molecular weight resin particles obtained by emulsion polymerization are obtained by emulsion polymerization without an emulsifier. (4) The method according to claim 1, wherein the high molecular weight resin particles have a particle size of 0.01 to 1 μm and a polymerization average molecular weight of 200,000 or more. (5) High molecular weight resin particles and monomer in a ratio of 5:95 to 50:
The method of claim 1, wherein the solution is formed by mixing in a weight ratio of 50. (6) The method according to claim 1, wherein the suspended particles are polymerized to form toner particles of 1 to 30 μm.