JPH07104613B2 - Method for manufacturing developing toner - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a developing toner used in electrophotography, and more specifically, it contains a coloring agent in a polymerization process of a fixing resin. However, the present invention relates to a method for producing a toner in which the particle size is in a range suitable for the toner and the particle size distribution is uniform.

(Prior Art) In the field of electrophotography, toner is used for the purpose of visualizing an electrostatic image. The toner particles are composed of a composition in which a colorant and, if necessary, another compounding agent such as a charge control agent are mixed in a resin medium in a certain particle size range, for example, a particle size range of 1 to 30 μm. As the resin medium, a resin having a desired electroscopic property and binding property, for example, a styrene resin or the like is used, and as the colorant, carbon black or another organic or inorganic color pigment is used. To be done.

The most typical method for producing an electrophotographic toner comprises a step of melt-kneading the above-mentioned resin medium and a colorant, cooling and pulverizing the kneaded composition, and classifying the pulverized material to make it uniform within a certain particle size range. However, the yield of the toner obtained by this pulverization / classification is low, and a large amount of equipment is required for these operations, which makes the manufacturing cost of the toner extremely high. In addition, since the shape of the obtained particles is irregular, the flowability of the toner is generally low, and blocking is likely to occur.

Heretofore, many proposals have been made for directly manufacturing a toner in a step of polymerizing a resin for the toner. A typical example thereof is a water-insoluble monomer in which a soluble polymerization initiator is dissolved, and an additive such as a colorant is further added, and the composition is mixed with a suitable dispersant such as a water-soluble polymer. The colored polymer particles are produced by suspending the mixture in an aqueous solution containing an inorganic powder, a surfactant and the like by high-speed shearing stirring and polymerizing the suspension.

(Problems to be Solved by the Invention) However, in this suspension polymerization method, the particle size of the final toner is determined by the suspension state of the monomer composition in water, and the particle size distribution is a single amount. Depending on how the body composition is put into water and how it is stirred, it is very broad and it is difficult to obtain particles having a single particle size. In addition, this suspension polymerization method generally produces only coarse particles of about several tens of μm to several mm, and it is difficult to obtain particles having a particle size of 1 to 30 μm, which are useful as toners for developers. Of course, it is possible to make the particle size of the produced toner finer by increasing the blending amount of the dispersant, but in this case, the dispersant is contained in the toner, and it tends to be sensitive to humidity. Deterioration of electrophotographic characteristics is likely to occur. In order to prevent this, a special post-treatment operation is required, and the number of steps is large and impractical.

In particular, the problem with toner by the suspension polymerization method is that
Unevenness in particle size, it is difficult to avoid mixing fine particles at a certain ratio, and such fine particles are particles consisting of a polymer alone containing no toner additives such as colorants. Therefore, even if it is mixed in a small amount, it may cause toner scattering or fogging during development, and may easily cause deterioration of toner fluidity. Also, even if these fine particles could be removed,
The obtained toner particles are significantly different from the initial compounding composition, and not only the desired characteristics cannot be obtained, but also the cost is increased due to the decrease in yield.

Therefore, an object of the present invention is to provide a method in which the above-mentioned drawbacks of the conventional production of toner for electrophotography are eliminated.

Another object of the present invention is to provide a colored resin which has a particle size constitution and a uniform particle size distribution suitable for use as a toner and which does not substantially contain an inhibitor for the electrophotographic properties of the toner.
Another object of the present invention is to provide a method for producing an electrophotographic toner which can be directly produced in a resin polymerization step.

Still another object of the present invention is to control the particle size of the colored resin in the polymerization step stably within the range of 1 to 30 μm, which is suitable for the toner, and maintain the particle size distribution evenly to prevent mixing of fine particles. It is an object of the present invention to provide a method for producing a toner that can be prevented.

(Means for Solving Problems) According to the present invention, as a fixing resin monomer, a colorant, a radical polymerization initiator having a solubility in water at 25 ° C. of 0.05 g / 100 cc or less, and a suspension stabilizer. A surface active agent in an amount less than the critical micelle concentration is mixed with water at a temperature lower than the polymerization temperature to prepare a suspension dispersion of monomers, and then the suspension dispersion is heated to a polymerization temperature range. A method for producing a developing toner by carrying out suspension polymerization is provided.

(Function) Principle In the suspension polymerization method, a monomer is dispersed and suspended in water by a suspension dispersion stabilizer, and polymerization is carried out in the presence of a radical polymerization initiator dissolved in the monomer. Inorganic fine powders, water-soluble polymer protective colloids, surfactants and the like are known as suspension stabilizers, but all of them have advantages and disadvantages in terms of particle size control of resin particles produced by polymerization. That is, the inorganic fine powder and the protective colloid are not yet sufficiently satisfactory for the suspension stabilizer, and the resin particles produced have a coarse particle size and are likely to have a very broad particle size distribution. On the other hand, the surfactant is excellent in suspension stability,
There is an unavoidable tendency to emulsify a part of the monomer, and it is inevitable to mix emulsion-polymerized particles having a fine particle size into the suspension-polymerized particles. In the present invention, as a suspension dispersion stabilizer, using a surfactant at a concentration lower than the critical micelle concentration,
As a radical polymerization initiator, its solubility in water at 25 ° C is 0.
In combination with the use of a radical initiator of 05 g / 100 cc or less, it becomes possible to homogenize the suspension polymerized particles to a particle size suitable for the toner and prevent mixing of fine polymerized particles.

That is, in the present invention, the use of a surfactant is indispensable from the viewpoint of controlling the suspension polymerized particles to have a particle size suitable for the toner and uniformizing the particle size distribution. However,
From the viewpoint of preventing the inclusion of emulsion-polymerized particles, the first condition is to use the surfactant at a concentration lower than the critical micelle concentration. The surfactant ionizes into long-chain ions (anions) and counter ions when the concentration is sufficiently low, but the long-chain ions aggregate at a certain concentration, that is, at a critical micelle concentration or more. However, it has a property of forming micelles and becoming colloidal ions. In the present invention, the surfactant is used at a concentration lower than the critical micelle concentration to prevent the formation of colloidal ions, that is, the formation of monomer emulsified particles.

According to the study of the present inventors, it is found that using a surfactant at a concentration lower than the critical micelle concentration during suspension polymerization is not sufficient to prevent the incorporation of fine emulsion-polymerized particles having a particle size. all right. To completely prevent the mixture of emulsion-polymerized particles, the solubility in water at 25 ° C is 0.05 g / 10
The second essential condition is to use a radical polymerization initiator of 0 cc or less.

In the present invention, the reason why the mixture of emulsion-polymerized particles is prevented by using the above-mentioned specific radical polymerization initiator is considered as follows. That is, in the suspension polymerization system, the monomers dissolved in water are present to some extent. The monomer dissolved in this water is initiated by the radical polymerization initiator which is also dissolved in water,
It is considered that the generated polymer radicals serve as nuclei, and the dissolved monomers in water are absorbed in the nuclei to cause growth to the emulsion polymerization particle size. On the other hand, according to the present invention, by setting the solubility of the radical polymerization initiator in water to be equal to or less than 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 to be.

Raw Material In the present invention, the monomer used is a radically polymerizable monomer, and the resulting polymer has the fixability and the electric detection property required for the toner, and the monomer has ethylenic unsaturation. One kind or a combination of two or more kinds is used under the above-mentioned restrictions. Suitable examples of such monomers are:
Monovinyl aromatic monomers, acrylic monomers, vinyl ester monomers, vinyl ether monomers, diolefin monomers, monoolefin monomers and the like.

The monovinyl aromatic monomer has the formula In the formula, R ₁ is a hydrogen atom, a lower alkyl group or a halogen atom, and R ₂ is a hydrogen atom, a lower alkyl group, a halogen atom, an alkoxy group, an amino group, a nitro group, a vinyl group or a carboxyl group. Aromatic hydrocarbons such as styrene, α-methylstyrene, vinyltoluene, α-chlorostyrene,
O-, m-, p-chlorostyrene, p-ethylstyrene, sodium styrenesulfonate, and divinylbenzene may be used alone or in combination of two or more, and the above-mentioned other monomers are as follows. Are listed respectively.

formula In the formula, R ₃ is a hydrogen atom or a lower alkyl group, R ₄ is a hydrogen atom, a hydrocarbon group having up to 12 carbon atoms, a hydroxyalkyl group,
Acrylic monomers, which are vinyl ester groups or aminoalkyl groups, such as acrylic acid, methacrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, phenyl acrylate , Methyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, β-hydroxy acrylate, γ-hydroxy acrylate, δ-hydroxy butyl acrylate, β-hydroxy methacrylate, γ-amino acrylate , Γ-NN-diethylamino acrylate propyl ester, ethylene glycol dimethacrylate ester, tetraethylene glycol dimethacrylate ester and the like.

formula In the formula, R ₅ is a hydrogen atom or a lower alkyl group, and vinyl esters such as vinyl formate, vinyl acetate, vinyl propionate and the like.

formula, In the formula, R ₆ is a monovalent hydrocarbon group having up to 12 carbon atoms, such as vinyl ether, for example, vinyl methyl ether, vinyl ethyl ether, vinyl-n-butyl ether, vinyl phenyl ether, vinyl cyclohexyl ether and the like.

formula, In the formula, each of R ₇ , R ₈ and R ₉ is a hydrogen atom, a lower alkyl group or a halogen atom, and the diolefins and the like include butadiene, isoprene and chloroprene.

formula, In the formula, each of R ₁₀ and R ₁₁ is a hydrogen atom or a lower alkyl group, and monoolefins, especially ethylene, propylene, isobutylene, butene-1, pentene-1, 4-methylpentene-1 and the like.

Suitable examples of color 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 S, hanzer yellow G,
Hansar Yellow 10G, Benzidine Yellow G, Benzidine Yellow GR, Quinoline Yellow Rake, Permanent Yellow NCG, Tartrazine Rake.

Orange pigment Red lead yellow lead, molybdenum orange, permanent tones
GTR, Pyrazolo Orange, Vulcan Orange, Indanthrene Priliant Orange RK, Benzidine Orange G, Indanthrene Pluriant Orange GK.

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

Purple pigment Manganese purple, fast violet B, methyl violet lake.

Blue pigment Navy blue, cobalt blue, alkali blue lake, pictoria blue lake, phthalocyanine blue, metal-free phthalocyanine blue, phthalocyanine blue partially chlorinated, fast sky blue, indanthrene blue B
C.

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

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

Extender barite powder, barium carbonate, clay, silica, white carbon, talc, alumina white.

Conventional magnetic material pigments include, for example, ferric tetroxide (Fe
₃ O ₄ ), iron sesquioxide (γ-Fe ₂ O ₃ ), zinc iron oxide (ZnFe ₂ O
_4), iron oxide yttrium _{(Y 3 Fe 5 O 12)} , oxide Kadoriumu (CDFE ₂ O _4), iron oxide gadolinium _{(Gd 3 Fe 5 O 12)} , oxidized iron-copper (CuFe ₂ O _4), oxidation Tetsunamari ( PbFe ₁₂ O ₁₉ ), iron neodymium oxide (NdFeO ₃ ), iron oxide barium (BaFe ₁₂ O ₁₉ ), magnesium iron oxide (MgFe ₂ O ₄ ), iron manganese oxide (MnFe _2).
O ₄ ), lanthanum iron oxide (LaFeO ₃ ), iron powder (Fe), cobalt powder (Co), nickel powder (Ni), etc. are known. Any one can be used.

In the present invention, an additive component which is desirable to be contained in the toner in addition to the above-described colorant may be blended in the polymerization system prior to the polymerization.

For example, for use as a two-component pigment, a charge control agent known per se, for example, an oil-soluble dye such as nigrosine base (CI5045) oil black (CI26150) and spirone black, a metal salt of naphthenic acid, and a fatty metal soap. , A resin acid soap and the like can be blended, and a release agent such as low molecular weight polyethylene, low molecular weight polypropylene, various waxes, and silicone oil can be contained in order to add an offset preventing effect to the toner.

An anionic surfactant is advantageously used as the surfactant used as the suspension dispersion stabilizer. Suitable examples thereof include, but are not limited to:

Fatty acid salts such as sodium oleate and potassium castor oil; higher alcohol sulfate salts such as sodium lauryl sulfate and sodium cetyl sulfate; alklycyl sulfonates such as sodium dodecylbenzenesulfonate; sodium alkylnaphthalenesulfonate, β -Naphthalenesulfonic acid formalin condensate sodium salt, etc .; Naphthalenesulfonic acid salt derivatives; Dialkylsulfosuccinic acid salts; Dialkylphosphoric acid salts; Polyoxyethylene alkyl ether sulfates; Polyoxyethylene alkyl ether sulfate triethanolamines; Polyoxy Ethylene alkylphenol ether sulfates, etc.

As the suspension dispersion stabilizer, water-insoluble inorganic powder may be used in combination with the above-mentioned surfactant. As the inorganic fine powder, those having a particle size of 0.001 to 5 μm are advantageously used. Suitable examples thereof are tricalcium phosphate, talc, bentonite, kaolin, titanium oxide, alumina,
Zinc white, aluminum hydroxide, magnesium hydroxide, basic magnesium silicate, titanium hydroxide, ferric hydroxide, barium sulfate, silica, magnesium carbonate, calcium carbonate and the like.

The radical polymerization initiator must be soluble in the above-mentioned monomer and have a solubility in water at 25 ° C. of 0.05 g / 100 cc or less. Hydroperoxides such as cumene hydroperoxide used in ordinary suspension polymerization,
Many of the azobis compounds such as dimethyl-2,2'-azobisisobutyrate do not meet this requirement. Suitable examples thereof include, but are not limited to: Lauryl peroxide, benzoyl peroxide, 2,2'-azobis-2,4-dimethylvaleronitrile, 1-phenylethylazodiphenylmethane, 2,2'-azobis-2,4,
4, -trimethylpentane and the like.

Polymerization method According to the present invention, a monomer to be a fixing resin, a colorant and a radical polymerization initiator, and optionally a toner compounding agent are prepared by using the above-mentioned surfactant which is a suspension dispersion stabilizer. It is dispersed in water, and this suspension dispersion is heated to carry out suspension polymerization. In this case, it is necessary to prepare the suspension dispersion liquid at a temperature lower than the polymerization temperature. That is, when the suspension dispersion liquid is prepared in the polymerization temperature range, the polymerization proceeds before the suspension dispersion particles containing the monomer are stably formed, so that the suspension dispersion particles containing the particle size are stable. This is because it is difficult to obtain toner particles having a uniform particle size because the polymerization proceeds before being formed.

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

The colorant may be added in an amount contained in the toner resin, and is generally 1 to 30% by weight, particularly 3% by weight, based on the charged amount of the monomer.
A range of from 20 to 20% by weight is suitable. When a magnetic material is used as a pigment, it is generally 5 to 30 per monomer charge.
0% by weight, especially 10 to 250% by weight, is suitable.

The blending amount of the radical initiator may be a so-called catalyst proper amount, and it is generally preferable to use it in an amount of 0.1 to 10% by weight based on the charged monomers.

In addition, the surfactant has a concentration lower than the critical micelle concentration,
Generally, it is preferable to use it by adding it to an aqueous medium at a concentration of 50 to 100% of the critical micelle concentration. When the inorganic powder is used in combination, the concentration of the inorganic powder in the aqueous medium is preferably 0.01 to 50% by weight, particularly 0.1 to 10% by weight.

The polymerization temperature and time may be those known in the art, and generally 40 to
Polymerization at a temperature of 100 ° C. for 1 to 50 hours is sufficient. still,
The reaction system may be stirred gently so that a homogeneous reaction occurs as a whole, and even if the reaction system is replaced with an inert gas such as nitrogen in order to prevent the polymerization from being suppressed by oxygen. Good.

Since the polymerization product after the reaction is obtained in the form of granules having the above-mentioned particle size range, the produced particles are filtered, washed with water or the like if necessary, and dried to obtain colored particles for toner.

If necessary, the colored particles for toner are sprinkled with carbon black, hydrophobic silica or the like to obtain the final toner.

(Effect of the Invention) According to the present invention, a toner having a particle size of 1 to 30 μm in the toner suitable particle size range and having a sharp particle size distribution can be obtained by a polymerization method. In particular, this toner is an emulsion having a fine particle size. It has the advantage that it contains substantially no polymerized particles. Thus, this toner has the advantages that it is excellent in fluidity and that it does not cause toner scattering or fog, and that the toner can be manufactured in an extremely high yield.

(Experimental Example) The present invention will be described in more detail with the following example.

Example 1 Styrene 80 parts by weight n-butyl methacrylate 20 parts by weight Carbon black (Printex L; made by Degussa) 5 parts by weight Charge control agent (Spiron Black TRH; made by Hodogaya Chemical Co., Ltd.) 1 part by weight Low molecular weight polypropylene wax ( Viscole 550P; Sanyo Kasei Co., Ltd.) 2 parts by weight 2,2'-azobis-2,4-dimethylvaleronitryl (V-65; Wako Pure Chemical Industries, Ltd.) 5 parts by weight The above toner composition is 0.2% sodium dodecyl sulfate. In addition to 400 parts by weight of the aqueous solution (critical micelle concentration 0.26%), TKr Auto Homo Mixer (made by Tokushu Kika Kogyo Co., Ltd.) was used for 6000 r.
Stirring was performed at a stirring speed of pm for 10 minutes to carry out suspension dispersion.

This dispersion was placed in a separable flask under a nitrogen stream at 60r.
The mixture was stirred at pm and polymerized at 60 ° C. for 6 hours. When the polymer was allowed to stand for a while, a precipitate was formed, and the supernatant liquid was transparent. The supernatant liquid is removed by decantation, the precipitate is dried, and the toner having a particle size of 5 to 15 μm is used.
Parts by weight were obtained. This toner is used as a copy machine DC-100 by Mita Kogyo Co., Ltd.
As a result of putting 1000 sheets into 1 and performing a copy test, a clear image without fog was obtained and toner scattering was small.

Example 2 Styrene 80 parts by weight n-butyl methacrylate 20 parts by weight Permanent Red FNG (manufactured by Sanyo Dye Co., Ltd.) 8 parts by weight Charge control agent (Bontron E-82 manufactured by Orient Chemical Co., Ltd.) 1 part by weight Low molecular weight polypropylene wax (Viscole 550P; 2 parts by weight Lauryl peroxide (manufactured by Wako Pure Chemical Industries, Ltd.) 3 parts by weight The above toner composition is mixed well, and 0.03% sodium dodecylbenzenesulfonate aqueous solution (critical micelle concentration 0.04%) together with 4 parts by weight of tricalcium phosphate. % Or less) 400 parts by weight, and the suspension was dispersed by stirring with a TK Auto Homomixer at a stirring speed of 8000 rpm for 10 minutes. This dispersion was polymerized in the same manner as in Example 1. The tricalcium phosphate was dissolved and removed with dilute hydrochloric acid, filtered and dried to obtain 108 parts by weight of a toner having a particle size of 5 to 15 μm. This toner was put into a copying machine DC-1001 manufactured by Mita Kogyo Co., Ltd., and a copying test was performed. As a result, clear images were obtained.

Comparative Example 1 Dimethyl 2,2'-azobisisobutyrate (V-60) was used instead of 2,2'-azobis-2,4-dimethylvaleronitrile.
1; manufactured by Wako Pure Chemical Industries, Ltd.) and the polymerization was carried out in the same manner as in Example 1 except that the polymerization temperature was 70 ° C. When the polymer was allowed to stand for a while, a black precipitate was produced, but the supernatant was clouded with many polymer particles of 1 μm or less containing no colorant. When the supernatant was removed by decantation and the precipitate was dried, only 84 parts by weight of a toner having a particle size of 5 to 15 μm was obtained. As a result of performing a copying test by putting this toner into a copying machine DC-1001 manufactured by Mita Kogyo Co., Ltd.,
Image density was low, fogging occurred, and severe toner scattering occurred in the copying machine.

Comparative Example 2 Polymerization was carried out in the same manner as in Example 1 except that the concentration of the sodium dodecyl sulfate aqueous solution was 0.5%. When the polymer was allowed to stand for a while, a black precipitate was produced, but the supernatant was clouded with many polymer particles of 1 μm or less containing no colorant. When the supernatant was removed by decantation and the precipitate was dried, only 90 parts by weight of a toner having a particle size of 5 to 15 μm was obtained. This toner was put in a copying machine DC-1001 manufactured by Mita Kogyo Co., Ltd., and a copying test was conducted. As a result, the image density was low and fogging occurred.

Comparative Example 3 Polymerization was performed in the same manner as in Example 2 except that cumene hydroxyperoxide was used instead of lauryl peroxide. Compared with the case of Example 2, the polymer had many fine particles of 1 μm or less of the polymer alone, and was slightly cloudy.

The polymer was washed with dilute hydrochloric acid, filtered and dried, then 5 to 15μ
Only 85 parts by weight of a toner having a particle diameter of m was obtained. This toner was put in a copying machine DC-1001 manufactured by Mita Kogyo Co., Ltd., and a copying test was performed. As a result, the image was slightly fogged.

Claims (1)

[Claims] 1. A monomer for fixing resin, a colorant, a radical polymerization initiator having a solubility in water at 25 ° C. of not more than 0.05 g / 100 cc at 25 ° C., and a surfactant as a suspension stabilizer in an amount less than the critical micelle concentration. Is mixed with water at a temperature lower than the polymerization temperature to prepare a suspension dispersion liquid of the monomer, and then the suspension dispersion liquid is heated to a polymerization temperature range to carry out suspension polymerization, thereby developing toner. A method of manufacturing.