JPH0774913B2 - Method for producing polymerized toner - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a toner used in a method for developing a latent image.

BACKGROUND ART Toner that visualizes an electrical or magnetic latent image and the like is used in various processes for forming and recording images.

As an electrophotographic method which is one of such image forming processes, many methods are known as described in, for example, US Pat. No. 2,297,691. In this electrophotographic method, a photoconductive substance is generally used,
An electric latent image is formed on the photoconductor by various means, and then the latent image is developed with toner to form a toner image, and the toner image is transferred to a transfer material such as paper as necessary. Thereafter, the toner image is fixed on the transfer material or the like by heating, pressurizing, solvent vapor or the like, whereby a copy is obtained.
As a method of developing with toner or a method of fixing a toner image, various methods have been conventionally proposed, and a method suitable for each image forming process is adopted.

Conventionally, toners used for these purposes are generally prepared by melting and mixing a coloring material composed of a magnetic material or a dye / pigment in a thermoplastic resin to uniformly disperse the coloring agent, followed by fine pulverization.
By classification, it has been manufactured as a toner having a desired particle shape.

According to this manufacturing method (pulverization method), a considerably excellent toner can be manufactured, but there is a certain limitation, that is, the selection range of the toner material. For example, the resin colorant dispersion must be sufficiently brittle to be comminuted in an economically available manufacturing apparatus. From this request, the resin colorant dispersion has to be made sufficiently brittle, and when the dispersion is actually pulverized at a high speed, it is easy to form a particle group having a wide particle size range. The problem arises that a proportion of excessively finely divided particles is included in this group of particles. Further, such a highly brittle material is more susceptible to pulverization or pulverization when actually used for development in a copying machine or the like.

Further, in this pulverizing method, it is difficult to completely and uniformly disperse solid fine particles such as magnetic powder or a coloring agent in the resin, and depending on the degree of dispersion of the solid fine particles, an increase in fog and an image density Careful attention must be paid to the officialization of this dispersion as it causes a decrease. Also,
Exposure of the colorant on the fracture surface of the colored resin fine powder may cause variations in toner development characteristics.

On the other hand, in order to overcome the problems of the toner by the pulverization method, a method for producing the toner by the turbidity polymerization method has been proposed. In this turbidity polymerization method, a monomer composition prepared by uniformly dissolving or dispersing a polymerizable monomer and a colorant (further, if necessary, a polymerization initiator, a charge control agent, and other additives) is suspended. The monomer composition particles are formed by charging into a water phase (that is, a continuous phase) containing a stabilizer and granulating with stirring to form toner particles.

The polymerization reaction product containing the particles thus suspension-polymerized is subjected to solid-liquid separation, and the solid particles are dried to be used as an actual toner.

This suspension polymerization method is an excellent method that can eliminate the above-mentioned adverse effects of the pulverization method by omitting the melt-kneading step and the pulverization step. As a toner for visualizing an image, various characteristics are required, for example, that an original image can be faithfully reproduced, durability, and environmental resistance are excellent.

Conventionally, in order to obtain a polymerized toner having these excellent properties, an improvement in a granulation process of a monomer composition (for example, an improvement in dispersion / granulation conditions of a dispersing means, a dispersant, etc.), or a polymerization process (For example, the improvement of the polymerization conditions such as the type of the polymerization initiator and the conditions for applying the polymerization initiator) is vigorously carried out, but a polymerized toner which further satisfies the above-mentioned various characteristics is desired.

OBJECT OF THE INVENTION An object of the present invention is to provide a method for producing a polymerized toner which solves the above problems.

Another object of the present invention is to provide a method for producing a polymerized toner having good image characteristics, particularly a polymerized toner which gives a high image density and is excellent in durability and environmental resistance.

Still another object of the present invention is to provide a manufacturing method for efficiently manufacturing a polymerized toner having good image characteristics.

SUMMARY OF THE INVENTION As a result of intensive studies conducted by the present inventors in order to obtain a polymerized toner having favorable image characteristics, it goes without saying that the granulation step and the polymerization step of the monomer composition as described above are important. Furthermore, it has been found that the process of separating the liquid component from the toner particles, which is a polymerization product, has an extremely large influence on the actual image characteristics of the polymerized toner.

The method for producing a polymerized toner of the present invention is based on the above findings, and more specifically, it is characterized in that toner particles produced by a suspension polymerization method are suspended and suspended in a gas and dried while forming a fluidized bed. To do.

The reason why the above-described effect is achieved in the toner of the present invention is not always clear, but according to the knowledge of the present inventor, it is presumed as follows.

That is, in the drying step of the conventional polymerized toner manufacturing method, since the toner particles are dried without flowing (similar to general polymer powder), water, residual solvent, etc. remaining on the surface of the toner particles evaporate. At this time, the toner particles are deformed based on the action of the capillary pressure generated between the contacting particles (unevenly evaporating water or the like from the particle surface).
It is presumed that the fusion occurred, and furthermore, the water, solvent, etc. on the toner surface were not sufficiently removed (from the viewpoint of the image quality characteristics of the polymerized toner) (even after drying for a relatively long time).

Therefore, in the conventional manufacturing method, the toner particles are deformed and fused in the drying step (even if the toner particles having a uniform particle shape and particle size are generated due to the improvement of the granulation and polymerization steps). Good image characteristics cannot be obtained, and on the surface of the toner (a very small amount that is not a problem for ordinary polymer fine powder).
It is presumed that the residual water and the like caused a decrease in the image density of the polymerized toner or a decrease in durability and environmental resistance.

On the other hand, in the manufacturing method of the present invention having the above-described structure, the gas and the toner particles are almost uniformly contacted in the fluidized bed, and water, residual solvent, etc. are uniformly and efficiently discharged from the particle surface. Since the toner particles are removed, the deformation, fusion or aggregation of the toner particles due to the non-uniform evaporation of the liquid component is significantly suppressed, and the toner particles flow in the fluidized bed by using the gas as a cushion. It is estimated that the deformation of the toner particles is suppressed.

Furthermore, in the present invention, since water and solvent (or residual monomer) on the toner surface are removed efficiently and sufficiently, it is possible to obtain a toner excellent not only in image characteristics but also in durability and environmental resistance. Presumed.

The production method of the present invention having such advantages is particularly suitably used as a toner suitable for a high-speed copying machine when producing a low melting point toner (Tg of about 60 ° C. or less), which will be required more in the future.

Hereinafter, the present invention will be described in more detail with reference to the drawings as necessary. In the following description, “%” and “part” representing the quantitative ratio are based on weight unless otherwise specified.

DETAILED DESCRIPTION OF THE INVENTION In the toner manufacturing method of the present invention, toner particles obtained by suspension-polymerizing a polymerizable monomer are used as a raw material. Such toner particles are powdery in terms of fluidity. The water content is preferably 40% or less, more preferably 30% or less. Here, the water content refers to the water content based on the moisture content, that is, the ratio of the water weight to the total weight (sum of the anhydrous toner weight and the water weight).

Toner particles having such a water content can be easily obtained by an ordinary solid-liquid separation means (for example, filtration). In order to obtain a toner having such a water content, a preliminary drying may be performed, if necessary. You may go.

In the present invention, any device capable of drying toner particles in a fluidized bed state can be used without particular limitation. For example, a fluidized bed dryer having an embodiment as shown in the schematic side sectional view in the drawings is used. It is preferably used.

With reference to the drawings, the fluidized bed dryer 1 has a cylindrical shape as a whole as shown in the drawing, a gas inlet 2 and a plate for rectifying the gas along a gas flow path. Board 3
Fluidized bed drying chamber 4 in which a fluidized bed of particles, gas and gas is formed
A bag filter 5 for trapping particles, an exhaust port 6,
It is composed of an exhaust blower 7. The drying chamber 4 has a cross-sectional area in a direction perpendicular to the gas flow path (as shown in the drawing), which is higher than the lower portion (the side of the plate 3) (the bag filter 5).
It is preferable to have such a shape that the side) is larger.

A raw material feeding hopper 9 and a screw feeder 10 for feeding the raw material toner 8 into the drying chamber 4 are mounted on the outer wall of the drying chamber 4 between the perforated plate 3 and the bag filter 5.

The drying operation using the dryer 1 is performed as follows, for example. That is, the raw material (polymerized toner particles) 8 charged in the material charging hopper 9 is supplied into the fluidized bed drying chamber 4 by the screw feeder 10. On the other hand, when hot air is introduced from the gas inlet port 2 and introduced into the drying chamber 4 through the perforated plate 3, the toner particles 8 are blown up by the gas and form a fluidized bed with the gas in the drying chamber 4. Form. This gas finally passes through the exhaust port 6,
It is exhausted by the exhaust blower 7.

On the other hand, the toner particles 8 supplied into the drying chamber 4 are floated in the drying chamber 4 to form a fluidized bed by coming into contact with the above-mentioned gas and being loosened. Inside this fluidized bed,
The toner particles are mixed with the gas almost uniformly as a whole, and the particle surface is brought into uniform contact with the gas, so that the attached water or the residual solvent (or residual monomer) is efficiently removed from the particle surface. The water, solvent, etc. thus removed are discharged outside the system by the exhaust blower 7.

The toner particles blown up to the upper portion of the drying chamber 4 (on the side of the exhaust port 6) are captured by the bag filter 5 mounted on the upper portion of the drying chamber 4 (for example, by applying vibration to the bag filter 5). ) Toner particles are bag filter 5
Is wiped off and returned to the lower side (inside the drying chamber 4) again.

The type of gas introduced into the drying chamber 4 is not particularly limited, and an inert gas such as nitrogen may be used,
From the viewpoint of cost and the like, it is preferable to use air.

The temperature of this gas is preferably about 20 to 70 ° C (depending on the relative humidity described later), and more preferably about 35 to 50 ° C. It is preferable that the temperature of the gas is higher than the normal temperature (from the viewpoint of more efficient drying) (for example, 35 ° C. or higher) and introduced into the drying chamber 4 through the inlet.

On the other hand, it is desirable that the temperature of the gas be a temperature equal to or lower than the glass transition point of the toner 8 in order to suppress the deformation / fusion of the raw material toner 8 as much as possible.

The gas is preferably dehumidified to a relative temperature of about 0 to 50% (further, a relative humidity of about 0 to 30%) and then introduced into the drying chamber 4.

Further, when the flow velocity of the gas introduced into the drying chamber 4 is too high, the toner 8 does not form a fluidized bed, and the toner is simply dried.
When the flow velocity is too low, the toner 8 does not float in the drying chamber 4. Therefore, it is necessary to adjust the flow rate of the gas so that the toner particles supplied into the drying chamber 4 substantially form a fluidized bed. The official flow velocity varies depending on the specific gravity and particle size of the raw material toner particles, but when the dryer 1 shown in the drawing is used, it is generally about 0.1 to 2.0 m / sec (in the vicinity of the plate plate 3). Is preferred.

The time required for drying depends on the water content of the raw material powder 8. However, when the fluidized bed dryer 1 having the configuration shown in this drawing is used, for example, toner powder having a water content of 20% is used as the raw material.
It is possible to dry to a water content of 0.2% or less in about 60 minutes.

As the fluidized bed dryer preferably used in the present invention, specifically, a fluidized bed dryer FBA manufactured by Okawara Seisakusho
Type, FBAW type, FB type, FBS type, FCAS type, FCS type; indirect heating dryer manufactured by Kurimoto Iron Works.

As described above, in the method of the present invention, the suspension-polymerized toner containing almost no water and residual solvent can be efficiently produced in a short time by drying the raw materials in the fluidized bed.

On the other hand, in the conventional method for producing a polymerized toner,
Since drying was performed without flowing the drying raw material using a vacuum dryer or a dehumidifying dryer, it was not possible to sufficiently remove water and residual solvent from the surface of the toner particles (as described above). It is considered that even if it could be removed sufficiently, it took a very long time and the deformation of the toner particles was unavoidable.

The polymerized toner obtained by the production method of the present invention provides a stable triboelectric charge amount between the toner and the sleeve or between the toner and the toner carrier such as the carrier. Therefore, by using the toner obtained by the present invention, a high image density can be obtained, and even when the developer is continuously used for a long period of time, the initial characteristics are maintained and a high quality image can be stably obtained for a long period of time. be able to.

Further, even when used under high temperature and high humidity environmental conditions, the toner obtained by the present invention gives a stable developer triboelectric charge amount, and the charge amount hardly changes as compared with the normal temperature and normal humidity condition. It is possible to give an image that is faithful to the latent image with less fog and lowering of image density. Even when the toner obtained according to the present invention is used under low temperature and low humidity conditions, the triboelectrification amount distribution shows almost no change from that at normal temperature and normal humidity, so that there is no reduction in image density or fog, and there is no image blurring. It is possible to remarkably suppress the scattering at the time of transfer.

In the production method of the present invention, a polymerized toner obtained by suspension-polymerizing a polymerizable monomer is used as a raw material.

In the present invention, the polymerizable monomer constituting such a polymerized toner includes styrene, o-methylstyrene, m
-Methylstyrene, p-methylstyrene, p-methoxystyrene, p-phenylstyrene, p-chlorostyrene, 3,4-dichlorostyrene, p-ethylstyrene, 2,4
-Dimethyl styrene, pn-butyl styrene, p-te
rt-butyl styrene, pn-hexyl styrene, p-
n-octyl styrene, pn-nonyl styrene, p-
Styrene and its derivatives such as n-decylstyrene and pn-dodecylstyrene; ethylenically unsaturated monoolefins such as ethylene, propylene, butylene and isobutylene; halogens such as vinyl chloride, vinylidene chloride, vinyl bromide and vinyl fluoride. Vinyl chlorides; vinyl esters such as vinyl acetate, vinyl propionate and vinyl benzoate; methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, methacrylic acid Α-Methylene aliphatic monocarboxylic acid esters such as dodecyl, 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate; Methyl acid, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, propyl acrylate, n-octyl acrylate, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, phenyl acrylate Acrylic esters such as; vinyl ethers such as vinyl methyl ether, vinyl ethyl ether, vinyl isobutyl ether; vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone, methyl isopropenyl ketone; N-vinyl pyrrole, N-vinyl carbazole, N-vinyl compounds such as N-vinylindole and N-vinylpyrrolidone; vinylnaphthalenes; acrylic acid or methacrylic acid derivatives such as acrylonitrile, methacrylonitrile and acrylamide Vinyl monomer etc. is a combination of two or more thereof, if desired, are preferably used.

When polymerizing such a monomer, it is preferable to add a polymer having a polar group, a copolymer or a cyclized rubber as an additive to polymerize the monomer.

To obtain the polymerized toner (raw material) used in the present invention,
A polymerizable monomer composition containing a polymer having a polar group, a copolymer, or a cyclized rubber at the time of polymerization is suspended in an aqueous phase in which a dispersant having an opposite charge to the polar polymer or the like is dispersed. It is more preferable to polymerize.

In such an embodiment, the cationic or anionic polymer, copolymer or cyclized rubber contained in the monomer composition is the oppositely charged anionic or cationic polymer dispersed in the aqueous phase. The dispersant is electrostatically attracted to each other (on the surface of the particles that will become toner during polymerization), and the dispersant covers the surface of the particles to prevent the particles from coalescing and stabilize the particles. Furthermore, since the polar polymer added at the time of polymerization gathers on the surface layer of the toner particles, the particles have a kind of shell-like form, and the obtained toner particles become pseudo capsules.

Such relatively high molecular weight (eg, weight average molecular weight of 5,00
(0 to 500,000) polar polymer, copolymer or cyclized rubber is used to provide toner particles with excellent blocking resistance, phenomenon resistance and abrasion resistance, while the inside of the toner particles is relatively low. By using a material having a molecular weight and polymerizing so as to contribute to the improvement of the fixing property, a toner satisfying the contradictory requirements of the fixing property and the blocking resistance can be obtained.

The polar polymer (hereinafter, used to include a polar copolymer) and the reverse chargeable dispersant which can be used in the present invention are exemplified below.

(1) As the cationic polymer, a polymer of a nitrogen-containing monomer such as dimethylaminoethyl methacrylate or diethylaminoethyl acrylate; or styrene,
There is a copolymer of an unsaturated carboxylic acid ester or the like and the nitrogen-containing monomer.

(2) Examples of anionic polymers include nitrile-based monomers such as acrylonitrile, halogen-containing monomers such as vinyl chloride, unsaturated carboxylic acids such as acrylic acid, anhydrides of unsaturated dibasic acids, and nitro-based polymers. A polymer of monomers; or a cyclized rubber,
There are polyester resins and the like.

(3) As the anionic dispersant, a water-soluble polymer such as a partially saponified vinyl acetate polymer; or Aerosil #
There are colloidal silicas such as 200 and # 300 (manufactured by Nippon Aloezil).

(4) As the cationic dispersant, aluminum oxide,
There are hydrophilic positively charged silica fine powders such as magnesium hydroxide and aminoalkyl-modified colloidal silica.

A cyclized rubber may be used instead of the polar polymer described above.

On the other hand, as the colorant added to the above-mentioned monomer composition as necessary, a known dye or pigment as well as a polar substance, that is, a substance magnetized by being placed in a magnetic field is used.
Examples of such magnetic substances include powders of ferromagnetic metals such as iron, cobalt and nickel, or magnetite,
Examples include powders of alloys and compounds such as hematite and ferrite. Particle size is 0.05-5 μm, preferably 0.1-1 μm
Magnetic fine particles of m are preferably used. The content of the magnetic particles is preferably 10 to 60% by weight (further 25 to 50% by weight) based on the weight of the toner.

Further, these magnetic fine particles may be treated with a hydrophobizing agent such as a silane coupling agent or a titanium coupling agent, or a suitable reactive resin. In this case, although depending on the surface area of the magnetic fine particles and the density of the hydroxyl groups existing on the surface, sufficient dispersibility of the magnetic particles can be obtained with an amount of the treatment agent of 5% or less based on the weight of the untreated magnetic particles. Also, the physical properties of the toner are not adversely affected.

If necessary, a charge control agent, a colorant, and a fluidity modifier may be added to the toner. The charge control agent and the fluidity modifier may be used as a mixture (external addition) with toner particles. Examples of the charge control agent include metal-containing dyes and nigrosine, examples of the colorant include conventionally known dyes and pigments, and examples of the fluidity modifier include colloidal silica and fatty acid metal salts. Further, for the purpose of increasing the amount, a filler such as calcium carbonate or fine powder silica is added to the toner weight in an amount of 0.
You may mix | blend in a toner in the range of 5 to 20 weight%. Further, in order to prevent aggregation of toner particles and improve fluidity, a fluidity improver such as Teflon fine powder may be added to the toner.

Further, for the purpose of improving the releasability at the time of heat roll fixing, waxes generally used as a releasing agent in the toner such as a hydrocarbon compound and carnauba wax (preferably a softening point).
50 to 120 ° C.) may be added. In this case, such a hydrocarbon compound or the like is usually added to the monomer composition (before polymerization), but 1 to 200 parts of the waxes is added to 100 parts of the polymerizable monomer. (Further, 2 to 100 parts) is preferably added.

In this case, for example, the above-mentioned hydrocarbon compound is hydrophobic and has a relatively low molecular weight, so that it is more difficult for the hydrocarbon compound to appear on the toner surface as compared with the polar polymer, and the hydrocarbon compound is pushed into the toner particles. At the time of fixing, such a hydrocarbon compound comes out of the inside of the toner and remarkably improves the toner fixing property and offset property. At this time, it is considered that the hydrocarbon compound functions as a plasticizer, a lubricant, and an oil-like function.

In the present invention, examples of the hydrocarbon compound include paraffin polyolefin having carbon of ₆ or more,
More specifically, for example, 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.), PE-130 (manufactured by Hoechst). , Mitsui High Wax 110P (Mitsui Petrochemical), Mitsui High Wax 22
0P (Mitsui Petrochemical), Mitsui High Wax 660P (Mitsui Petrochemical) and others. Particularly preferably used hydrocarbon compounds are low molecular weight polyethylene, low molecular weight polypropylene and paraffin.

As a polymerization initiator for polymerizing the above-mentioned polymerizable monomer, any suitable polymerization initiator, for example, azobisisobutyronitrile (AIBN), benzoyl peroxide, methyl ethyl ketone peroxide, isoproperperoxy carbonate , Cumene hydroperoxide, 2,4-dichlorolylbenzoyl peroxide, lauroyl peroxide and the like can be used. Generally, it is sufficient to use about 0.5-5% by weight of the monomer of the polymerization initiator.

As a suitable dispersion medium (or continuous phase) used for suspending and polymerizing the monomer composition, for example, one obtained by incorporating any suitable stabilizer in the aqueous phase can be preferably used.

Examples of such stabilizers include polyvinyl alcohol, gelatin, methyl cellulose, methyl hydroxypropyl cellulose, ethyl cellulose, sodium salt of carboxymethyl cellulose, polyacrylic acid and salts thereof, starch, gum alginate, zein,
Casein, tricalcium phosphate, talc, barium sulfate, bentonite, aluminum hydroxide, secondary hydroxide
Any one or a mixture of iron, titanium hydroxide, thorium hydroxide and the like can be used. This stabilizer is used in a stabilizing amount in the continuous phase, preferably in the range of about 0.1 to 10% by weight, based on the polymerization of the polymerizable monomer.

Further, in order to finely disperse the inorganic dispersant, a surfactant in the range of 0.001 to 0.1% by weight based on the weight of the polymerizable monomer may be used. This surfactant is for promoting the intended action of the dispersion stabilizer, and specific examples thereof include sodium dodecylbenzene sulfonate, sodium tetradodecyl sulfate, sodium pentadecyl sulfate, sodium octyl sulfate, and allyl. -Sodium alkyl-polyether sulfonate, sodium oleate, sodium laurate, sodium caprate, sodium caprate, potassium stearate, calcium oleate, 3,3-disulfone diphenylurea-4,4-diazo-bis-amino -8-Naphthol-6-
Sodium sulfonate, ortho-carboxybenzene-
Examples thereof include azo-dimethylaniline, 2,2,5,5-tetramethyl-triphenylmethane-4,4-diazo-bis-β-naphthol-sodium disulfonate, and the like.

Also, when an easily soluble monomer is used in water, emulsion polymerization occurs in water at the same time, 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. This may prevent emulsion polymerization in the aqueous phase. Further, in order to increase the viscosity of the continuous phase (dispersion medium) and prevent the particles from coalescing, a polyhydric alcohol such as glycerin or glycol may be added to water. Also, NaCl, KCl, and Na ₂ SO ₄ are used to reduce the solubility of easily soluble monomers in water.
It is also possible to use salts such as.

At the time of polymerizing the polymerizable monomer, the following cross-linking agent may be present to carry out the polymerization to form a cross-linked polymer in the toner.

Examples of the cross-linking agent include divinylbenzene, divinylnaphthalene, divinyl ether, divinyl sulfone, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, ethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, 1,3-butylene glycol dimethacrylate, 1,6-hexane glycol dimethacrylate, neopentyl glycol dimethacrylate, dipropylene glycol dimethacrylate, polypropylene glycol dimethacrylate, 2,2'-bis (4-methacryloxydiethoxyphenyl) propane,
2,2'-bis (4-acryloxydiethoxyphenyl)
A general crosslinking agent such as propane, trimethylolpropane trimethacrylate, trimethylolpropane triacrylate, tetramethylolmethane tetraacrylate, dibromoneopentyl glycol dimethacrylate, and allyl phthalate can be appropriately used.

If the amount of these cross-linking agents used is too large, the toner is less likely to melt, and the fixability is reduced. If the amount of the cross-linking agent used is too small, the properties such as blocking resistance and durability required for the toner deteriorate, and during heat roll fixing, part of the toner does not adhere completely to the paper and adheres to the roller surface. However, it becomes difficult to prevent the offset phenomenon of transferring to the next paper. Therefore, the amount of these crosslinking agents used is preferably 0.001 to 15% by weight (more preferably 0.1 to 10% by weight) based on the total amount of the monomers.

When granulating the monomer composition in the aqueous dispersion medium, it is preferable to granulate using, for example, a homomixer or a homogenizer having a turbine and a stator rotating at high speed. Generally, it is preferable to adjust the stirring speed and time so that the monomer composition has a particle size of 30 μm or less.
More specifically, the rotation speed is 10-30 m / se when the weekly speed of the turbine is
The granulation time is not particularly limited, but it is preferably 5 to 60 minutes. The ratio of the monomer composition to the dispersion medium is preferably 200 to 3,000 parts by weight based on 100 parts by weight of the monomer composition.

By further polymerizing the monomer composition granulated as described above, the toner particles used in the present invention can be suitably obtained.

During this polymerization, the polymerization reaction proceeds, but the stirring may be carried out to such an extent that the dispersion state is maintained by the action of the dispersion stabilizer and the particles are prevented from settling. Polymerization temperature is 40
It is preferable to carry out the polymerization at a temperature of not lower than 0 ° C (further 60 to 90 ° C). The polymerization time may be set so that the polymerization is completed, and specifically, 2 to 24 hours are good.

To remove the dispersant, the particles obtained by polymerization are treated with an acid or alkali, or other method (or the dispersant is removed by washing without treatment), filtered, and then dried as described above. A toner is obtained in this way. When it is not necessary to remove the dispersant, the particles produced by the polymerization may be directly filtered and dried to obtain a toner.

After obtaining the toner by the production method of the present invention, fine powder may be removed by an air classifier, if necessary.

EFFECTS OF THE INVENTION As described above, according to the present invention, there is provided a method for producing a polymerized toner in which toner particles obtained by suspension polymerization of a polymerizable monomer are dried while being in a fluidized bed state with a gas.

The polymerized toner obtained by the production method of the present invention is prevented from being deformed and fused in the toner particles in the drying step, and is removed from the surface of the particles by a liquid component such as water which impairs image characteristics. The polymerized toner provides high image density and is excellent in durability and environmental resistance.

Hereinafter, the present invention will be described in more detail with reference to examples.

Example ( ^* Titanium coupling agent (manufactured by Ajinomoto Co., Inc.)) The components of the above formulation were dissolved in a container while heating to 70 ° C to disperse the magnetic substance. Next, in a container equipped with TK-Homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.), which is a mixing device having a high shearing force, while maintaining the dispersion liquid obtained above at 70 ° C., at 10,000 rpm for about 30 minutes. After mixing, 0.8 part by weight of azobisisobutyronitrile was further added and mixed for 10 minutes to obtain a monomer composition.

70 parts of 360 parts by weight of a water-based dispersion medium in which 1.2 parts by weight of Aerogel # 200 (manufactured by Nippon Aerozil) is dispersed in a granulation tank equipped with an Adjomo mixer (made by Tokushu Kika Kogyo).
The monomer composition obtained above was put into this dispersion medium while being heated to 0 ° C., and stirred at 3000 rpm for 30 minutes for granulation.

The dispersion liquid containing the granulated monomer composition particles was transferred to a polymerization kettle, heated and kept at 70 ° C., and stirred at 50 rpm with an ordinary Ikari type stirrer to complete the polymerization of the monomer composition. . 1.6 parts by weight of NaOH was added to the obtained polymerization product,
After removing the dispersant by treating with stirring at room temperature for 4 hours,
By washing with water and filtering, a toner powder having a water content of 20% and containing a small amount of styrene monomer was obtained.

With reference to the drawings, the obtained toner powder is put into a hopper 9 of a fluidized bed dryer FBS-0.5 type (manufactured by Okawara Seisakusho) with a bag filter having a structure as shown in the drawing, and a screw feeder 10 is used. Was introduced into the drying chamber 4 to dry. At this time, 5 kg of toner powder 8 was introduced into the drying chamber 4, and warm air at 45 ° C. was blown into the drying chamber 4 from the inlet 2 through the perforated plate 3 at a wind speed of 0.5 m / sec. The powder 8 was dried in the drying chamber 4 while forming a fluidized bed. The toner was taken out of the drying chamber 4 after 60 minutes, and the water content was measured by Karl Fischer titration. As a result, it was 0.1% or less. In addition, the amount of styrene monomer measured by gas chromatography is less than the detection limit (20
ppm) How was it?

To 100 parts of the polymerized toner thus obtained, 0.6 parts of hydrophobic silica was added.
When an image forming test was carried out with a copying machine NP150Z (manufactured by Canon Inc.) after adding parts to make it a developer, the decrease in density due to durability (10,000 sheets) was within a practically acceptable range.

Also, in the image forming test under high temperature and high humidity (32.5 ° C, 90%), the result without any practical problem was obtained.

Comparative Example Toner powder obtained by polymerizing a monomer composition was dispersed in the same manner as in the example, and dried at 45 ° C. under vacuum. After 60 minutes, the toner was taken out and the water content of the toner was measured and found to be 15%.

An image forming test was conducted in the same manner as in Example 1 using the thus obtained polymerized toner, and only a rough image was obtained even at room temperature and normal humidity.

[Brief description of drawings]

The drawing is a schematic side sectional view showing a specific example of a fluidized bed drying apparatus used in the toner manufacturing method of the present invention. 1 ... Fluidized bed dryer 2 ... Gas inlet 3 ... Drain plate 4 ... Drying chamber 5 ... Bag filter 6 ... Exhaust outlet 7 ... Exhaust blower 8 ... Raw toner powder 9 ... Raw material input Hopper 10 ... Screw feeder

Claims (2)

[Claims] 1. A method for producing a polymerized toner, characterized in that toner particles produced by a suspension polymerization method are suspended and suspended in a gas and dried while forming a fluidized bed. 2. The method for producing a polymerized toner according to claim 1, wherein a heated gas is used as the gas.