JPH07120072B2 - Method for producing polymerized toner - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a polymerized toner by a suspension polymerization method.

[Prior Art] Conventionally, a toner is generally a thermoplastic resin in which a colorant and other additives are melt-mixed, uniformly dispersed, and then pulverized by a fine pulverizer and classified by a classifier to obtain a desired particle size. Have been manufactured. This manufacturing method can produce a fairly good toner, but has potential problems due to the grinding process. That is, the toner obtained using the crushing method must have brittleness so that the material is crushed to some extent. However, if the toner is too brittle, it will be too finely pulverized, and the fine powder will have to be cut later in order to obtain a toner having an appropriate particle size distribution, which results in an increase in cost. Further, in the developing device of the copying machine, it is sometimes further pulverized. Further, when a material having a low melting point or a material having a pressure fixing property is used in order to improve the heat fixing property, a fusion phenomenon may occur in the crushing device or the classifying device, and continuous production may not be possible.

Other requirements for the toner are that it has a triboelectric charging property suitable for development, that it forms an excellent image, that there is no change in performance when left alone, and that it does not coagulate (blocking, etc.),
It has suitable heat or pressure fixing characteristics and does not contaminate the surface of the photoreceptor. Especially in fixing, the offset phenomenon in which toner adheres to the fixing roller and is re-transferred onto the next copy paper is always a problem.To prevent this, a releasing agent such as silicone oil is applied to the fixing roller. Application has been done. However, in recent years, a method has been generally used in which the toner is made to contain a polyolefin such as polypropylene or polyethylene and the release agent is not applied to the fixing roller or the application amount is reduced to prevent the offset. recent years,
In order to further improve the offset resistance, it has been attempted to add a larger amount of polyolefin, or to use a polyolefin having a lower melting point, but fusion may occur in a pulverizer or a classifier, and the pulverization method It was difficult to put it into practical use.

Therefore, a method of producing a toner from a monomer by a suspension polymerization method has been proposed as one means for overcoming the problems of the pulverization method.

Conventionally, in the suspension polymerization method, when a monomer composition having at least a colorant, a polymerizable monomer and a polymerization initiator is granulated into a toner particle size in an aqueous medium and the polymerization initiator is decomposed by heat. The polymerizable monomer is polymerized by radicals generated in the above to form a polymer, thereby producing a polymerized toner. That is,
Since this method does not include a crushing step, brittleness is not necessary and the shape is spherical, so that it has characteristics such as excellent fluidity and uniform triboelectrification. In recent years, improvements in image quality of copied images, speeding up of copying machines and / or energy saving have been aimed at, and the development characteristics of toner have been further improved, and blocking resistance, fluidity and abrasion resistance have not been lowered, and more A toner capable of forming a good fixed image by low-temperature fixing and / or low-pressure fixing, and an efficient manufacturing method of the toner are desired.

In order to improve the developing characteristics of the toner, there is a method of sharpening the particle size distribution of the toner, and in the suspension polymerization method, a method of sharpening the particle size distribution is as follows: There is a method of lowering the viscosity to facilitate granulation. The greater the amount of various additives other than the polymerizable monomer in the monomer composition, the higher the need to raise the temperature of the monomer composition to lower its viscosity. However, in the conventional suspension polymerization method, since the polymerization initiator is already present in the monomer composition during the granulation step, the temperature at which the polymerization initiator decomposes to generate radicals (for example, about 50
If the temperature is higher than (~ 60 ° C) (for example, about 80 ° C), the polymerization initiator decomposes too rapidly and is lost rapidly, so the polymerization reaction of the polymerizable monomer can proceed satisfactorily. There wasn't.

As another method of sharpening the particle size distribution, there is a method of classifying the polymerized toner after completion of the suspension polymerization reaction to sharpen the particle size distribution of the polymerized toner. In the toner manufacturing method using the pulverization method, it was possible to mix coarse toner and ultrafine particle toner having a particle size outside the specified range classified by classification with the starting materials and circulate them to the melt-kneading step for reuse. In the production method by the turbid polymerization method, it is difficult to mix the unspecified coarse toner and the ultrafine particle toner separated by the classification with the monomer composition and to reuse them. Is very problematic in terms of yield. Therefore, there is a demand for a method for producing a polymerized toner that does not require a classifying step or a method for recycling coarse particles classified by classification.

Further, for the purpose of lowering the fixing temperature of the polymerized toner and / or lowering the fixing pressure, a low softening point compound such as solid paraffin or low molecular weight polyolefin having shape retention at room temperature in the monomer composition. When a large amount of is added, the polymerizable monomer and the low softening point compound are generally poor in compatibility and difficult to uniformly disperse at low temperature. It was necessary to disperse and granulate the monomer composition in an aqueous medium.

However, as described above, in the conventional suspension polymerization method, since the polymerization initiator already exists at the time of dispersion granulation, there is a limit to raising the liquid temperature of the aqueous medium, and therefore the addition of the low softening point compound is limited. The quantity was very limited.

[Problems to be Solved by the Invention] An object of the present invention is to provide a method for producing a polymerized toner, which solves the problems associated with the conventional methods for producing a suspension polymerization toner as described above.

An object of the present invention is to provide a method for producing a polymerized toner having a spherical shape, good fluidity, and a sharp particle size distribution.

An object of the present invention is to provide a method for producing a polymerized toner having a predetermined particle size distribution with good yield.

An object of the present invention is to provide a method for producing a polymerized toner capable of low-temperature fixing and / or low-pressure fixing for energy-saving fixing or for high-speed machines.

[Means and Actions for Solving Problems] The present invention relates to a method for producing a polymerized toner by a suspension polymerization method, in which a monomer composition containing at least a polymerizable monomer and a colorant is mixed at a polymerization temperature. Dispersion granulation in an aqueous medium heated to a higher temperature than that, adding a substantially water-insoluble polymerization initiator to the aqueous medium cooled to the polymerization temperature after granulation, suspension polymerization A method for producing a polymerized toner characterized by the above.

In the present invention, a polymerization initiator for polymerizing the polymerizable monomer is added to the aqueous medium after granulating the monomer composition. Therefore, it is possible to granulate by setting the temperature of the aqueous medium, which is the dispersion medium of the monomer composition, to a high temperature. Furthermore, a classification step is provided after granulation to classify the monomer composition particles having a predetermined particle size and the monomer composition particles having a non-specified particle size, and then a polymerization initiator is added to carry out polymerization. It is also possible to mix the separated monomer composition particles having a non-specified particle size with another monomer composition before the polymerization step, and to carry out dispersion granulation for reuse. is there. Further, during the granulation step, the temperature of the aqueous medium can be raised to high temperature without considering the decomposition temperature of the polymerization initiator, so that a substantial amount of paraffin or low molecular weight polyolefin such as polyolefin may be added to the monomer composition. A low softening point compound that is insoluble in the polymerizable monomer can be added in a large amount, and even if a large amount is added, granulation can be performed at a high temperature, so that a low temperature having a sharp particle size distribution can be obtained. Polymerized toners that can be fixed and / or low pressure fixed can be produced.

According to the knowledge of the present inventors, when a water-soluble polymerization initiator is used, the produced polymerized toner has reduced moisture resistance, and the development characteristics and blocking resistance at high temperature and high humidity deteriorate. In order to produce a polymerized toner having excellent environmental characteristics, it is necessary to use a substantially water-insoluble polymerization initiator. When a substantially water-insoluble polymerization initiator is used, in a system in which the monomer composition is previously dissolved and mixed as in the conventional case, the polymerization initiator is evenly distributed to each monomer composition particle. It is expected that, even in a system in which a substantially water-insoluble polymerization initiator is added after granulating a monomer composition in an aqueous medium as in the present invention, a good polymerization reaction occurs in each particle. That is surprising.

The polymerization initiator used in the present invention is substantially water-insoluble. The substantially water-insoluble polymerization initiator in the present invention has a solubility of 1 g or less with respect to 100 g of water at room temperature, preferably 0.5 g or less with respect to 100 g of water, and particularly preferably 100 g of water. It has a low solubility of 0.2 g or less. When it has a solubility of more than 1 g in 100 g of water, the decomposition product of the polymerization initiator remaining on the surface of the polymerized toner particles after the completion of the polymerization undesirably lowers the moisture resistance of the polymerized toner. Further, the polymerization initiator used in the present invention is soluble in the polymerizable monomer, and is usually used in an amount range (2 to 5 parts by weight of the polymerization initiator relative to 100 parts by weight of the monomer).
Has a property of being dissolved in a polymerizable monomer. As the polymerization initiator usable in the present invention, 2,2'-azobis-
(2,4-dimethylvaleronitrile), 2,2'-azobisisobutyronitrile, 1,1'-azobis (cyclohexane-1-carbonitrile), 2,2'-azobis-4-methoxy-2, Azo- or diazo-type polymerization initiators such as 4-dimethylvaleronitrile and other azobisisobutyronitriles (AIBN); benzoyl peroxide, methyl ethyl ketone peroxide, isopropyl peroxycarbonate, cumene hydroperoxide, 2,4-
Examples thereof include peroxide type polymerization initiators such as dichlorylbenzoyl peroxide and lauroyl peroxide.
In the production method of the present invention, the polymerization initiator preferably has a melting point equal to or higher than the polymerization temperature (usually 50 ° C. or higher). It is also preferable to use a mixture of two or more polymerization initiators for the purpose of controlling the molecular weight and molecular weight distribution of the polymer or the reaction time. In that case, it is preferable to use at least one having a melting point at a temperature corresponding to the liquid temperature in the aqueous medium at the time of polymerization or at a temperature lower than that. This is because the polymerization initiator is oiled at the liquid temperature during the polymerization reaction, so that the polymerization initiator or the radicals generated from the polymerization initiator is added to each of the monomer composition particles dispersed after being added to the aqueous medium. It is because it is imparted more favorably. By the way, the 2,2'-azobis- (2,4-dimethylvaleronitrile) used in the examples is a meso form (mp 55-57 ° C) and a dl form (mp
74-77 ° C.), the mixture starts melting at about 45 ° C. and ends melting at about 70 ° C. The amount of the polymerization initiator used is 0.1 to 20 parts by weight, preferably 1 to 10 parts by weight, based on 100 parts by weight of the polymerizable monomer. If it is less than 0.1 parts by weight, it is difficult to uniformly apply the polymerization initiator to each monomer composition particle, and if it exceeds 20 parts by weight, the molecular weight of the polymerization product becomes too low and the polymerization reaction becomes too low. Is more likely to occur unevenly.

The suspension polymerization reaction is usually performed at a polymerization temperature of 50 ° C or higher,
The upper limit temperature is set in consideration of the decomposition rate of the polymerization initiator. If the set polymerization temperature is too high, the polymerization initiator will be rapidly decomposed, which is not preferable. In the present invention,
Since it is not necessary to allow the polymerization initiator to be present in the monomer composition during suspension granulation, the liquid temperature of the aqueous medium during granulation is, for example, 75
Granulation can be easily performed by lowering the melt viscosity of the monomer composition at a temperature of not lower than 0 ° C.

After confirming that the formed monomer composition particles have a predetermined particle size, lower the liquid temperature of the aqueous medium containing the particles to the polymerization temperature (for example, 55 to 70 ° C), and then start the polymerization. Add agent. By lowering the liquid temperature of the aqueous medium, the shape retention of the monomer composition particles is improved, and coalescence of the particles is suppressed. The polymerization reaction time varies depending on the type of polymerization initiator and the polymerization temperature, but is usually 2 to 30 hours.

In the production method of the present invention, since dispersion granulation at high temperature is possible, it is possible to add a large amount of the low softening point compound as an additive to the monomer composition. The low softening point compound in the present invention has a softening point of 40 to 130 measured by the ring and ball method.
Those having a temperature of 50 ° C, preferably 50 to 120 ° C. If the softening point is less than 40 ° C, the blocking resistance of the toner is insufficient, and if it exceeds 130 ° C, the effect of lowering the fixing temperature is small. As the low softening point compound, paraffin, low molecular weight polyolefin, modified wax having an aromatic group,
Hydrocarbon compounds with alicyclic groups, natural wax, carbon number
Examples thereof include long-chain carboxylic acids having 12 or more long-chain hydrocarbon chains and esters thereof. Specifically, paraffin wax (manufactured by Nippon Oil Co., Ltd.), paraffin wax (manufactured by Nippon Seiro Co., Ltd.), microwax (manufactured by Nippon Oil Co., Ltd.), microcrystalline wax (manufactured by Nippon Seiro Wax Co., Ltd.), hard paraffin wax (manufactured by Nippon Seiro Wax Co., Ltd.), PE-130 (Hoechst), Mitsui High Wax 110P (Mitsui Petrochemical), Mitsui High Wax 22
0P (Mitsui Petrochemical), Mitsui High Wax 660P (Mitsui Petrochemical), Mitsui High Wax 210P (Mitsui Petrochemical), Mitsui High Wax 320P (Mitsui Petrochemical), Mitsui High Wax 410P (Mitsui Petrochemical) ), Mitsui High Wax 420P (Mitsui Petrochemical), Highlets T-100X (Mitsui Petrochemical), Highlets T-200X (Mitsui Petrochemical), Highlets T-300X (Mitsui Petrochemical); Petrosin 80 (Mitsui) Petrochemical), Petrosin 100 (Mitsui Petrochemical),
Petrosin 120 (Mitsui Petrochemical), Tuck Ace A-100
(Mitsui Petrochemical), Tack Ace F-100 (Mitsui Petrochemical), Tack Ace B-60 (Mitsui Petrochemical), Modified Wax JC-1141 (Mitsui Petrochemical), Modified Wax JC-21
30 (Mitsui Petrochemical), modified wax JC-4020 (Mitsui Petrochemical), modified wax JC-1142 (Mitsui Petrochemical), modified wax JC-5020 (Mitsui Petrochemical); beeswax, carnauba wax, Examples include montan wax. When a low softening point compound having a softening point of 100 ° C or higher is used, the liquid temperature of the aqueous medium is 100 ° C under pressure.
It is preferable to carry out dispersion granulation as described above.

The above-mentioned low softening point compound is a fixing temperature of the polymerized toner and / or
Alternatively, in order to lower the fixing pressure, it is preferable to mix 50 to 3,000 parts by weight with respect to 100 parts by weight of the polymerizable monomer, especially 1
00 to 1,000 parts by weight is preferred. If it is less than 50 parts by weight, it is insufficient to lower the fixing temperature, and if it exceeds 3,000 parts by weight, the blocking resistance and durability tend to be lowered.

The polymerizable monomer applicable to the present invention, styrene,
o-methylstyrene, m-methylstyrene, p-methylstyrene, p-methoxystyrene, p-phenylstyrene, p-chlorostyrene, 3,4-dichlorostyrene, p
-Ethylstyrene, 2,4-dimethylstyrene, pn-
Butyl styrene, p-tert-butyl styrene, pn-
Hexyl styrene, pn-octyl styrene, pn
-Nonylstyrene, pn-decylstyrene, pn-
Styrene and its derivatives such as dodecyl styrene; ethylenically unsaturated monoolefins such as ethylene, propylene, butylene, isobutylene; vinyl halides such as vinyl chloride, vinylidene chloride, vinyl bromide, vinyl fluoride; vinyl acetate, propion Vinyl esters such as vinyl acrylate and vinyl benzoate; acrylic acid, methacrylic acid, maleic acid, maleic acid half ester; methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, methacrylic acid α-methylene such as n-octyl, dodecyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate Aliphatic monocarboxylic acid esters;
Methyl acrylate, ethyl acrylate, acrylic acid n-
Butyl, isobutyl acrylate, propyl acrylate,
Acrylic esters such as n-octyl acrylate, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, phenyl acrylate; vinyl ethers such as vinyl methyl ether, vinyl ethyl ether, vinyl isobutyl ether Vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone, and methyl isopropenyl ketone; N-vinyl pyrrole, N-vinyl carbazole, N-
N-vinyl compounds such as vinylindole and N-vinylpyrrolidone; vinylnaphthalenes; acrylonitrile,
There are monomers having a reactive double bond such as vinyl group such as acrylic acid or methacrylic acid derivative such as methacrylonitrile and acrylamide. These may be used alone or in combination of two or more. Moreover, you may add the polymer of these polymerizable monomers in a monomer composition. Among the above-mentioned monomers, styrene or a combination of styrene having a substituent such as an alkyl group or a combination of styrene and another monomer is preferable in view of the developability and durability of the polymerized toner.

Further, when a polymer having a polar group, a copolymer or a cyclized rubber is added as an additive at the time of polymerizing the monomer to polymerize the monomer, a preferable polymerized toner can be obtained. A polymerizable monomer composition containing a polymer having a polar group, a copolymer, or a cyclized rubber is suspended in an aqueous phase in which a dispersant having an opposite charge to the polar polymer is dispersed and polymerized. It is preferable. That is, the cationic or anionic polymer, copolymer or cyclized rubber contained in the polymerizable monomer composition is a reversely charged anionic or cationic dispersant dispersed in an aqueous medium. A type of toner that attracts electrostatically on the surface of the particles that become the toner and prevents the particles from coalescing by covering the surface of the particles with a dispersant and stabilizes them, and the added polar polymer collects on the surface layer of the particles that become the toner. The resulting particles have a pseudo-capsule shape. Further, since a relatively high molecular weight polar polymer, copolymer or cyclized rubber is used, the polymerized toner particles are provided with excellent properties such as blocking resistance, developability and abrasion resistance. The polar polymers (including polar copolymers) and the oppositely charged dispersants that can be used in the present invention are exemplified below. The polar polymer has a weight average molecular weight measured by GPC of 5,000 to 500,000.
Those of are preferably used.

(I) Examples of the cationic polymer include polymers of nitrogen-containing monomers such as dimethylaminoethyl methacrylate and diethylaminoethyl acrylate, and copolymers of styrene and unsaturated carboxylic acid esters with the nitrogen-containing monomers. .

(Ii) Examples of anionic polymers include nitrile monomers such as acrylonitrile, halogen-containing monomers such as vinyl chloride, unsaturated carboxylic acids such as acrylic acid, unsaturated dibasic acids, and unsaturated dibasic acids. There are polymers of anhydrides and nitro monomers.

(Iii) Examples of anionic dispersants include Aerosil # 200,
There are colloidal silica such as # 300 (manufactured by Nippon Aerosil Co., Ltd.).

(Iv) Examples of the cationic dispersant include fine particles of hydrophilic positively charged silica such as aluminum oxide, magnesium hydroxide and colloidal silica modified with aminoalkyl.

A cyclized rubber having an anionic property may be used instead of the polar polymer.

To produce magnetically polymerized toner, magnetic particles are added to the monomer composition. The magnetic particles that can be used in the present invention include substances that are magnetized when placed in a magnetic field, such as iron,
Examples include powders of ferromagnetic metals such as cobalt and nickel, and powders of alloys and compounds such as magnetite, hematite and ferrite. Magnetic fine particles having a particle size of 0.05 to 5 μm, preferably 0.1 to 1 μm are used. The content of the magnetic particles is 10 to 60% by weight, preferably 25 to 50% by weight, based on the weight of the toner. Further, these magnetic fine particles may be treated with a treating agent such as a silane coupling agent or a titanium coupling agent, or an appropriate reactive resin. In this case, although depending on the surface area of the magnetic fine particles and the density of hydroxyl groups existing on the surface, sufficient dispersibility is obtained with a treatment amount of 5% or less, and the physical properties of the toner are not adversely affected. If necessary, a charge control agent, various colorants, and a fluidity modifier may be added to the polymerized toner. The charge control agent and the fluidity modifier may be used as a mixture (external addition) with toner particles. There are metal-containing dyes, nigrosine, etc. as charge control agents, and conventionally known dyes as colorants, pigments such as carbon black and grafted carbon black in which the surface of carbon black is coated with resin can be used. And, as the fluidity modifier, colloidal silica,
There are fatty acid metal salts and the like. Further, for the purpose of increasing the amount, a filler such as calcium carbonate or fine powder silica may be blended in the toner in the range of 0.5 to 20% by weight. Further, in order to prevent aggregation of the toner particles and improve fluidity, a fluidity improver such as Teflon fine powder may be added. Also, when a hydrocarbon compound or carnauba wax that improves releasability at the time of heat roll fixing is used as a low softening point compound, for example, a hydrocarbon compound is hydrophobic and has a low molecular weight, and thus is formed by polymerization. It is less likely to mix with the polymer and less likely to be exposed on the surface than the polar polymer, so that it is pushed into the polymerized toner. As a result, even if it contains a large amount of the low softening point compound, it is excellent in durability and blocking resistance because it is encapsulated. Then, the toner comes out of the inside at the time of fixing and remarkably improves the fixability and the offset resistance. At that time, the hydrocarbon compound is considered to act as a plasticizer, a lubricant, and an oil-like function.

The suspension method is to uniformly dissolve the colorant (including a magnetic material in the present invention), the polymerizable monomer, and the additive,
Alternatively, the dispersed monomer composition is used in an aqueous medium containing 0.1 to 50% by weight of a suspension stabilizer (for example, a sparingly soluble inorganic dispersant) (for example, 5 ° C or higher than the polymerization temperature, preferably 10 ° C).
The mixture is heated in the above temperature) and dispersed by an ordinary stirrer, homomixer, homogenizer or the like. Preferably the monomer droplets are of the desired toner particle size, generally
The stirring speed, the time, and the liquid temperature of the aqueous medium are adjusted so as to have a size of 30 μm or less (for example, a volume average particle diameter of 0.1 to 20 μm). Then, the liquid temperature of the aqueous medium is lowered to the polymerization temperature while stirring is carried out to the extent that the sedimentation of the particles is prevented so that the state of the dispersion stabilizer is almost maintained by the action of the dispersion stabilizer. The polymerization temperature is set to 50 ° C. or higher, preferably 55 to 80 ° C., particularly preferably 60 to 75 ° C., and the polymerization is carried out by adding a substantially water-insoluble polymerization initiator while stirring. After the completion of the reaction, the produced toner particles are recovered by an appropriate method such as washing, filtering, decanting, centrifuging, etc. and dried to obtain a polymerized toner. In the suspension polymerization method, usually 200 to 3000 parts by weight of water is used as an aqueous dispersion medium with respect to 100 parts by weight of the polymerizable monomer.

Also suitable stabilizers such as polyvinyl alcohol,
Gelatin, methyl cellulose, methyl hydropropyl cellulose, ethyl cellulose, sodium salt of carboxymethyl cellulose, polyacrylic acid and salts thereof, starch, gum alginate, zein, casein,
Any one or a mixture of tricalcium phosphate, talc, barium sulfate, bentonite, aluminum hydroxide, ferric hydroxide, titanium hydroxide, thorium hydroxide and the like is used as an aqueous medium to adversely affect the production method of the present invention. Those that are included to the extent not included may also be used.

Further, in order to uniformly disperse the inorganic dispersant, a surfactant may be used to the extent that it does not adversely affect the production method of the present invention. This is for promoting the intended action of the above dispersion stabilizer, and specific examples thereof include sodium dodecylbenzenesulfonate, sodium tetradecyl sulfate, sodium pentadecyl sulfate, sodium octyl sulfate, and allyl-alkyl-poly. Sodium ether sulfonate, sodium oleate, sodium laurate, sodium caprate, sodium caprate, sodium caproate, potassium stearate, calcium oleate, 3,3-disulfone diphenylurea-4,4-diazo-bis-amino -8-naphthol-6
-Sodium sulfonate, ortho-carboxybenzene-azo-dimethylaniline, 2,2,5,5-tetramethyl-
Mention may be made of sodium triphenylmethane-4,4-diazo-bis-β-naphthol-disulfonate, and others. Further, a water-soluble monomer simultaneously undergoes emulsion polymerization in water, and the resulting suspension polymer is contaminated with small emulsion-polymerized particles.Therefore, a water-soluble polymerization inhibitor such as a metal salt is added to emulsify it in the aqueous phase. It is also good to prevent polymerization. It is also possible to add glycerin, glycol or the like to water in order to reduce the viscosity of the aqueous medium and prevent the particles from coalescing during polymerization.
Also, to reduce the solubility of easily soluble monomers in water, NaCl, K
It is also possible to add Bronsted acids such as hydrochloric acid to the aqueous medium in order to increase the ionicity of salts such as Cl, Na ₂ SO ₄ or polar groups.

The polymerized toner obtained by the production method of the present invention can be applied to a known electrostatic image developing method. For example, a two-component developing method such as a cascade method, a magnetic brush method, or a microtoning method;
One-component developing method using magnetic toner such as conductive one-component developing method, insulating one-component developing method and jumping developing method; powder cloud method and fur brush method; holding on toner carrier by electrostatic force It is applicable to a non-magnetic one-component developing method in which the toner is conveyed to the developing section and is developed; and an electric field curtain developing method in which the toner is conveyed to the developing section and developed by the electric field curtain method.

[Examples] Hereinafter, the present invention will be described in detail based on Examples.

Example 1 The above components were mixed with an attritor at a temperature of 80 ° C. for 4 hours to prepare a monomer composition.

254 parts by weight of the obtained monomer composition, 20 parts by weight of amino-modified silica (100 parts by weight of Aerosil 200 treated with 5 parts by weight of aminopropyltriethoxysilane) and 0.
Distilled water 1200 containing 25 parts by weight of 1N hydrochloric acid and heated to 85 ° C
Add to a part by weight of an aqueous medium under stirring with a TK homomixer,
After charging, the mixture was stirred for 15 minutes at 10,000 rpm to carry out dispersion granulation.

After granulation, the liquid temperature was lowered to 60 ° C, and 3 parts by weight of 2,2'-azobis- (2,4-dimethylvaleronitrile) and 1.5 parts by weight of 2,2'-azobisisobutyronitrile were used as a polymerization initiator. Added to the aqueous medium and stirred for 30 minutes. Further, the stirring was changed to a paddle blade stirring, and stirring was carried out at 60 ° C. for 10 hours to complete the polymerization.

The obtained polymerized toner-containing aqueous medium is cooled and dehydrated,
Washing with sodium hydroxide solution to dissolve and remove amino-modified silica, washing with water, dehydration, and drying (if necessary, fine particles of unnecessary component particles are removed to remove them) Volume average particle size
A 6.5 μm (measured with a Coulter counter using a 100 μm aperture) toner was obtained. The obtained toner did not cause blocking even if left in an environment of 50 ° C. for one day.

10 parts by weight of the obtained toner, 0.1 part by weight of zinc stearate powder, 0.1 part by weight of hydrophobic silica (Aerosil R972, manufactured by Nippon Aerosil Co., Ltd.), and an average particle size of 40 μm formed of triiron tetraoxide and an epoxy resin. 90 parts by weight of carrier particles were mixed to prepare a developer, and development was performed under the following conditions.

The developing device shown in FIG. 1 was used. Image carrier 1
Has a selenium photosensitive member, the peripheral speed of the photosensitive member is 100 mm / sec, the maximum potential of the electrostatic charge image formed on the image carrier 1 is +750 V, the outer diameter of the sleeve 2 is 20 mm, and the peripheral speed is 100 mm / sec. Seconds of magnet
The magnetic flux density in the vertical direction on the sleeve surface of the N and S poles is 1000 gauss, the thickness of the developer layer is 200 μm, the sleeve 2 and the image carrier 1
The gap was 300 μm, the bias voltage applied to the sleeve was DC voltage component +200 V, AC voltage component was 3.0 KHz, and development was performed at 1400 V _PP . The electrostatic latent image is well developed, the developed toner image is electrostatically transferred to plain paper, and the toner image on the plain paper is heated under a pressure of 10 Kg / cm ² with a hot roller fixing device (nip width 7 mm, paper When the image was fixed through the advancing speed of 150 mm / sec), it was well fixed at the fixing temperature of 100 ° C.

Example 2 2000 parts by weight of carnauba wax (softening point 84 ° C.) and 155 ° paraffin instead of 4000 parts by weight of paraffin 155 ° F.
A polymerized toner was produced in the same manner as in Example 1 except that 2000 parts by weight of F (softening point 69 ° C.) was used and the temperature of the aqueous medium during dispersion granulation was 90 ° C. A toner image on plain paper obtained in the same manner as in Example 1 was fixed at a fixing temperature of 100 with the same fixing device as in Example 1.
When it was fixed at ℃, it was fixed well.

Comparative Example 1 A polymerization initiator was dissolved and mixed in advance in a monomer composition,
When dispersion granulation was carried out in the same manner as in Example 1 in an aqueous medium at 85 ° C., the polymerization initiator rapidly decomposed by heat, and unreacted styrene and oligomer were produced in large amounts due to insufficient polymerization reaction. No polymerized toner was obtained.

Comparative Example 2 Except that the liquid temperature of the aqueous medium at the time of dispersion granulation was 60 ° C.,
When the same procedure as in Example 1 was performed, only a polymerized toner having many coarse particles having a particle size of 100 μm or more and having an extremely wide particle size distribution was obtained.

Example 3 The above components were mixed with an attritor for 4 hours to prepare a monomer composition. Separately 20 parts by weight of amino-modified silica, 0.1N hydrochloric acid
75 parts by weight of an aqueous medium consisting of 25 parts by weight and 1200 parts by weight of distilled water
The mixture was heated to ℃, 244 parts by weight of the above monomer composition was added to the aqueous medium under stirring with a TK homomixer, and after the addition, 30 rpm at 10,000 rpm.
After stirring for a minute and after granulation, the aqueous medium was cooled to 60 ° C. As a polymerization initiator, 8 parts by weight of 2,2'-azobis- (2,4-dimethylvaleronitrile) and 4 parts by weight of 2,2'-azobisisobutyronitrile were added, and the mixture was further stirred for 30 minutes. Then, while stirring at 100 rpm with a normal stirrer, 60
The reaction was carried out at 0 ° C for 10 hours. After that, when post-treatment was carried out in the same manner as in Example 1, the volume average particle size was 4.6 with a sharp particle size distribution.
A polymerized toner having a size of μm was obtained. The polymerized toner obtained contained only about 2.0% by weight or less of particles having a particle size of 10 μm or more.

The polymer produced from styrene and 2-ethylhexyl methacrylate contained in the obtained polymerized toner was measured by gel permeation chromatography (using a molecular weight measuring device Waters 150C column A-80M) to obtain a weight average polystyrene equivalent. It was confirmed to have a molecular weight (w) of 23,039 and a number average molecular weight (n) of 10,633.

Comparative Example 3 A polymerization initiator was previously mixed and dissolved in the monomer composition,
A polymerized toner was prepared in the same manner as in Example 3 except that dispersion granulation was carried out at 60 ° C., and then polymerization was carried out at 60 ° C.

The obtained polymerized toner had an average particle size of 6.5 μm, but the particle size distribution was wider than in Example 3. The obtained polymerized toner contained about 12% by weight or more of particles having a particle size of 10 μm or more. Also, the polymerized toner is w23,747 and n
It has 10,721, and it was confirmed that the polymerization reaction also occurred in the same manner as in the conventional method.

[Effects of the Invention] As described above, according to the production method of the present invention, a polymerized toner containing a large amount of a low softening point compound can be obtained, and a good image can be obtained at low pressure and low temperature. Further, a spherical polymerized toner having good fluidity and a sharp particle size distribution can be obtained.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing a developing device used in Examples and Comparative Examples of the present invention. 1 ... Photosensitive drum, 2 ... Sleeve, 3 ... Magnet roller, 4 ... Developer, 5,6 ... Development bias power supply, 10
…… Doctor blade.

Claims (1)

[Claims] 1. A method for producing a polymerized toner by a suspension polymerization method, wherein a monomer composition containing at least a polymerizable monomer and a colorant is heated in an aqueous medium at a temperature higher than the polymerization temperature. A method for producing a polymerized toner, which comprises dispersion-granulating in step (1), adding a substantially water-insoluble polymerization initiator to the aqueous medium cooled to the polymerization temperature after granulation, and performing suspension polymerization.