JPH0820757B2 - Method for manufacturing toner for developing electrostatic image - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a toner for developing an electrostatic charge image in an image forming method such as an electrophotographic method, an electrostatographic method, and an electrostatic printing method, and more specifically, The present invention relates to a method for producing a toner for developing an electrostatic charge image by an improved suspension polymerization method, which has a granulation step for efficiently forming particles having a sharp particle size distribution.

BACKGROUND ART Conventionally, in an electrophotographic method, an electrostatic recording method, an electrostatic printing method, or the like, methods of developing an electrostatic charge image formed on a recording medium are roughly classified into various pigments and dyes in an insulating liquid. A liquid developing method using a dispersed developer, and a cascade method, a hair brush method, a magnetic method using fine particles called toner in which a coloring agent such as carbon black is dispersedly contained in a natural or synthetic polymer or wax. There are so-called dry developing methods such as a brush method, an impression method, and a powder cloud method.

The liquid developing method is troublesome in processing the developer and has a problem that a specific unpleasant odor is generated during and after development and fixing. Therefore, the dry developing method mainly using the toner is put to practical use. ing.

The toner for electrostatic image development used in the dry developing method is usually, for example, a vinyl-based polymer such as polystyrene or polyacrylic ester, an epoxy-based polymer, a petroleum-based polymer, a binder composed of an ester-based condensate, and the like, for example. It is manufactured by mixing with a colorant composed of carbon black, melting and kneading, cooling and pulverizing, and further classifying so that the toner particle size becomes 1 to 50 μm. The toner formed in this manner is required to satisfy various characteristics such as storage stability, durability, moisture resistance, electrostatic characteristics, fluidity, fixability and imageability.

It is said that most of the dry toners currently on the market are manufactured by this crushing method, because forming the toner by the above-mentioned so-called crushing method has many advantages.

However, this method has many problems. In other words, in the crushing method, the wind-type collision crusher used in the main part of pulverization in the crushing process uses a large amount of compressed air, which requires a large amount of equipment cost and consumes electric power during operation. Therefore, these costs occupy most of the toner processing cost. In particular, recently, a toner having a sharp particle size distribution or a toner having a small particle size has been demanded due to the demand for high quality of a copied image. It is difficult to generate a toner having a sharp distribution or a toner having a small particle size, which considerably increases the cost. Further, when a toner having a sharp distribution or a toner having a small particle size is generated by a pulverization method, the particle size distribution of the pulverized product tends to be broad and a large amount of unnecessary ultrafine powder tends to be generated. Is extremely difficult to remove.

Furthermore, in order to be effectively crushed in this crushing method,
Since it is necessary for the toner material to have moderate brittleness,
The selection of raw material is limited to the range having such brittleness. Further, when a softer material is used to improve the fixing property of the toner, the heat generated during the pulverization and the pressure for the pulverization easily cause fusion in the devices used in various steps. In such a case, it becomes impossible to continuously operate the toner manufacturing apparatus for a long time.

In order to overcome these problems, a method for producing a toner by a suspension polymerization method, which does not involve dry pulverization, has been proposed. This method is an excellent method that can eliminate the above-mentioned adverse effects by omitting the melting and kneading step and the crushing step. However, in the dry toner production by the conventional suspension polymerization method, New problems are emerging.

That is, firstly, in the toner production by the usual suspension polymerization method, a granulation step of granulating a liquid monomer composition containing a polymerizable monomer and a colorant in a liquid dispersion medium is performed. However, there is a problem that it is very difficult to efficiently control the particle size to a desired value. Secondly, in the current suspension polymerization method, the particle size distribution of the polymer particles produced is wide, and polymer particles having a large particle size are produced, so the weight ratio of particles in the appropriate particle size range is small. There is a problem that productivity is not good. In the above-mentioned pulverization method, those removed by the classification operation for obtaining an appropriate particle size range, after being mixed with the raw material again, can be reused through a kneading step,
In this suspension polymerization method, it is difficult to reuse the resulting polymer particles having a bad particle size at present.

In the suspension polymerization method, in order to solve the above-mentioned problems of particle size distribution, particles of a monomer composition having a particle size capable of finally producing a toner having a desired particle size distribution are prepared. Although it is necessary to stably produce a product in a high yield in the granulation process, many problems remain to be solved in the conventional suspension polymerization method in this respect.

One of the most important of these problems is the problem of dispersion stabilizers for obtaining proper particle size distribution. That is, in the suspension polymerization method, the main steps are carried out in a liquid medium (usually water is used as a medium), but in the granulation step, dispersion and stabilization are performed in order to generate and stabilize the monomer composition particles. Agents are used. As such a dispersion stabilizer, a poorly water-soluble inorganic fine powder such as BaSO ₄ , CaSO ₄ , CaCO ₃ or silicic acid (silica), a water-soluble polymer such as polyvinyl alcohol or gelatin, or a water-soluble surfactant is usually used. Etc. are used alone or in combination.

These dispersion stabilizers have strong hydrophilicity due to their roles, and when they remain in the toner formed, the developing ability and the transfer efficiency are reduced mainly due to the decrease in the chargeability of the toner. In particular, under high humidity conditions, the copy density is lowered, the resolution is lowered, and the image quality such as blemishes and black spots is lowered. Therefore, from this point, it is required to reduce the amount of the dispersion stabilizer used, while using a small amount of the dispersion stabilizer to reduce the particle size of the monomer composition,
Moreover, the problem of sharpening the particle size distribution must be solved.

In order to solve this problem, attempts have been made to improve the material of the dispersion stabilizer itself and to reduce the amount of the dispersion stabilizer used.However, in the conventional dispersion method, simply reducing the dispersion stabilizer would reduce the particle size of the monomer composition particles. Becomes coarse and has a wide particle size distribution, secondary aggregation of the monomer composition particles frequently occurs in the subsequent polymerization step, and it becomes difficult to obtain a polymer having an appropriate particle size.
In particular, when trying to obtain a toner having a sharp particle size distribution or a toner having a small particle size, this secondary aggregation becomes a very serious problem.

Object of the Invention An object of the present invention is to provide a toner production method capable of efficiently producing a toner having an extremely narrow average particle size distribution, in which the toner for developing an electrostatic image by a suspension polymerization method can be easily controlled. To provide.

Another object of the present invention is to provide a method for efficiently producing a dry toner having a small particle size.

Still another object of the present invention is to provide a method for producing a toner having a uniform and sharp particle size distribution while reducing the amount of the dispersion stabilizer used in the production of the toner by the suspension polymerization method. .

Still another object of the present invention is to improve the powder property,
An object of the present invention is to provide a method for producing a toner having good transfer, fixing and cleaning properties.

It is still another object of the present invention to provide a low cost and highly productive toner manufacturing method.

SUMMARY OF THE INVENTION As a result of intensive studies to solve the above-mentioned various problems, the present inventors have found that, in the coexistence of a dispersion stabilizer, a shearing force based on two or more high shearing force stirring devices arranged in the same granulation container. Granulating the monomer composition under the interaction of not only allows granulation with a uniform and sharp particle size distribution (even with smaller amounts of dispersion stabilizer), but also It has been found that it is possible to significantly improve the uniform dispersibility of the colorant in the polymerized toner particles.

The toner manufacturing method of the present invention is based on such knowledge, and more specifically, a dispersion stabilizer containing a monomer composition containing at least a polymerizable monomer and a colorant in a granulation container. And when granulating by dispersing in a liquid dispersion medium substantially incompatible with the above-mentioned polymerizable monomer; two or more high-shear stirring devices arranged in the same granulating container; It is characterized by being used and granulated.

The reason why the above-described effects are obtained in the present invention is not necessarily clear, but is presumed as follows.

In the granulation step of the present production method, the monomer composition is subjected to shearing force, impact, and turbulent flow based on the action of two or more high shearing force stirring devices arranged in the same granulating vessel in the presence of the dispersion stabilizer. The particles are granulated by the above method. At this time, the granulation efficiency is remarkably improved due to the synergistic effect of the impact of the dispersion liquids flowing out from the respective stirring devices and the complicated turbulent flow generated around the respective stirring devices.

Further, in this granulation step, the finely divided monomer composition particles dispersed and suspended in the liquid dispersion medium are subjected to a predetermined stabilizing action of the dispersion stabilizer, and have a large particle diameter of a certain level or more. Coarse composition particles having the above are further atomized by the action of the above-mentioned shearing force, impact, and turbulent flow, but the above-mentioned composition particles having a predetermined particle size have a relative protective effect by the dispersion stabilizer at this particle size. Due to the increase, the number of the composition particles having the above-mentioned predetermined particle size increases remarkably within a short time because the particles are more difficult to be made into fine particles.

Therefore, according to the production method of the present invention, the improvement of the granulation efficiency and the increase of the dispersion stabilizer protecting action are combined, so that the particle size distribution of the monomer composition particles which is extremely sharp is short. Estimated to be obtained in time.

Furthermore, in the present invention, the dispersibility of the colorant in the monomer composition particles is remarkably improved, which is presumed to be due to the following reasons.

That is, in the monomer composition particles containing a pigment (particularly, magnetic particles having a high specific gravity) as the colorant, aggregation and uneven distribution of the colorant tend to occur. Providing the particles with a strong and non-uniform shearing force (from a single stirrer) as in conventional granulation processes results in more uneven distribution of the colorant among the more finely divided monomer particles. It is estimated that it will be remarkable.

On the other hand, in the granulation step of the present invention, in order to apply more equalized shearing force to the monomer composition particles from two or more high shearing force stirring devices arranged in the same granulating vessel. The uneven distribution of the coloring agent is unlikely to occur between the particles subdivided by the shearing force. In addition, since the time interval until the once subdivided monomer composition particles are subdivided is short, aggregation and uneven distribution of the coloring agent in the particles hardly occur during this time. In the present invention, it is presumed that improvement of the uniform dispersibility of the colorant in the monomer composition particles is achieved by combining these two effects.

In particular, when the monomer composition contains a polymerization initiator, the above-mentioned difference in uniform dispersibility of the colorant becomes more remarkable. In such a case, the viscosity of the monomer composition particles is increased even in the granulation step, so that the coloring agent, which has been relatively freely moving until then, aggregating and repeating discretely, is gradually blocked in its movement, It is presumed that it is difficult for the coloring agent once aggregated and unevenly distributed to be dispersed again.

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

DETAILED DESCRIPTION OF THE INVENTION In the production method of the present invention, a monomer composition containing a polymerizable monomer such as styrene, a colorant such as carbon black, and a polymerization initiator (if necessary) is dispersed. In the presence of a stabilizer, two or more high-shear-force stirring devices in a liquid dispersion medium disperse by shearing force, impact, or turbulent flow.
It is suspended and granulated preferably as particles having an average particle size of 15 μm or less.

In the present invention, as such a high-shear stirring device, a turbine-type stirrer for applying a high shearing force to a dispersion liquid by a turbine and a stator rotating at high speed as shown in a schematic side sectional view in FIG. 1, or A high speed disperser (1a in FIG. 4 (c) described later) that gives a high shearing force to the dispersion by a stirring blade that rotates at high speed is preferably used.

With reference to FIG. 1, such a turbine-type stirrer 1
Comprises a turbine 2 rotating at a high speed, a stator 3 for applying a shearing force to the dispersion liquid between the turbine 2, a turbine bearing 4 provided with a dispersion liquid outlet 4a, and a dispersion liquid inlet 5a. It is composed of a bottom plate 5.

In such a turbine type stirrer 1, the dispersion liquid 6 composed of the monomer composition and the liquid dispersion medium enters the stirrer 1 through the injection port 5a and is generated between the turbine 2 and the stator 3 which rotate at high speed. After being stirred by strong shearing force, impact, and turbulent flow to form micron-order monomer composition particles, they flow out from the dispersion liquid outlet 4a.

In the stirrer 1 having the above-described structure, the high-viscosity turbine 2a having a shape as shown in the schematic perspective view of FIG. 2 (a) (there is no bottom plate in this case) depending on the viscosity of the monomer composition. ,
Alternatively, a low-viscosity turbine 2b having a shape as shown in the schematic perspective view of FIG. 2 (b) is preferably used. 3 (a) and 3 (b) are schematic side cross-sectional views showing a state in which the high-viscosity turbine 2a and the low-viscosity turbine 2b are arranged in the stator 3, respectively (however,
The turbines 2a and 2b are shown in a schematic side view. ).

As such a turbine type stirrer 1, it is preferable to use a stirrer such as TK Homomixer, TK Unimixer, TK Combimix manufactured by Tokushu Kika Kogyo Co., Ltd.

On the other hand, as described above, in the present invention, a high-speed disperser having a stirring blade that rotates at high speed is also preferably used as the high-shear stirring device. This high-speed disperser forms micron-order particles by stirring the dispersion liquid at high speed by the shearing force, impact, and turbulent flow of a stirring blade. As this high-speed disperser, for example, TK homodisbar manufactured by Tokushu Kika Kogyo Co., Ltd. is preferably used.

In the present invention, a stirring device that causes a large flow in the liquid, such as a device such as an anchor type mixer, has little effect of particle formation, but is useful for adjusting the flow of the liquid in the container. Due to the synergistic effect of the two high-shear stirring devices, more preferable particle formation can be performed.

A preferable combination of stirrers used in the present invention is to use two turbine stirrers 1 (for example, TK homomixer) in the granulating vessel 6 as shown in a schematic side sectional view in FIG. 4 (a). Is. In this case, as shown in FIG. 4 (b), an agitator such as an anchor type mixer
A combination of 7 is more preferable.

Another preferable combination is a combined use of a turbine type stirrer 1 such as a TK homomixer and a high speed disperser 1a such as a TK homodisbar as shown in a schematic perspective view in FIG. 4 (c). In this case, it is more preferable to further combine the stirrer 7 such as the anchor type mixer.

In the present invention, the above-mentioned two or more high shear stirring devices may be arranged in the same granulation container, and the mode (position, interval, etc.) of the arrangement is not particularly limited, but the dispersion liquid in the granulation container is not limited. From the point of averaging the shearing force to be applied, so as to be symmetric with respect to the perpendicular line passing through the center of the bottom surface of the granulation container 6,
It is preferable to arrange two or more stirring devices.

Further, the shape of the granulation container is preferably a container having a round bottom. It is considered that this is because there is no corner or dead space that hinders the flow of liquid.

Further, it is preferable that the positions of the stirring section of the stirrer are installed so that both are at the same height.

In such a granulation step, when a polymerization initiator is contained in the monomer composition, such a monomer composition is mixed with the progress of the polymerization even at the time of granulation. The viscosity of the dispersion increases as it gradually changes from the polymer to the polymer. In this case, the granulating property of the stirrer may gradually decrease as the viscosity increases, and it may be difficult to form fine particles.

In order to solve such a problem, it is conceivable to lower the granulation temperature (to slow down the progress of polymerization) for the granulation, but the molecular weight distribution required as a toner characteristic also changes, which is not preferable. In addition, it may be difficult to lower the granulation temperature from the viewpoint of the solubility of the added material (for example, a substance such as wax).

On the other hand, it is possible to granulate at a temperature at which polymerization does not substantially progress (remarkably low temperature) and then to raise the temperature after granulation to polymerize, but granulation may be difficult for the above reasons.

However, according to the present invention, by applying shearing force simultaneously from two or more stirrers, the efficiency of granulation is significantly increased, and even when the polymerization initiator is included in the monomer composition, the temperature It is possible to efficiently perform granulation in a short time and achieve preferable fine particle formation without being substantially affected by.

Further, as described above, in the present invention, since the dispersibility of the colorant in the polymerized toner produced is remarkably improved, the toner particles having a small content of the colorant, or the toner containing substantially no colorant. Generation of particles (particularly in fine powder toner) is extremely small.

Such an improvement in the dispersibility of the colorant is particularly remarkable when a polymerization initiator is contained in the monomer composition or when the colorant is magnetic particles having a high specific gravity.

It is considered that this is because in the present invention (as described above), the generation of particles having a small amount of the coloring agent is extremely small because the non-uniform force as in the aggressive granulation due to the action of the strong shearing force does not work. To be

The dispersibility of the colorant is one of the very important characteristics as a toner in terms of forming a clear image or maintaining the quality of an initial image during continuous use.

In the granulating step of the present invention, when a solid fine powder dispersion stabilizer such as silica is used as the dispersion stabilizer, the coarse monomer composition particles are atomized and at the same time form an aggregate. Since the agglomerates of the fine powder dispersion stabilizer, which did not work effectively, are further dispersed and come closer to the more effectively distributed particles, the dispersion stabilizing ability of the dispersion stabilizer as a whole is improved. As a result, the finely divided monomer composition particles are protected by the fine powder dispersion stabilizer having improved dispersion stabilizing ability. Therefore, the possibility that the monomer composition particles are further subdivided is extremely low as compared with the conventional granulation method.

Further, when the dispersion stabilizer is a solid fine powder dispersion stabilizer such as silica fine powder, it is also preferable to add a dispersion step of the fine powder dispersion stabilizer itself before this granulation step.

Here, the step of dispersing the fine powder dispersion stabilizer refers to a step of reducing the aggregates of the dispersion stabilizer in the dispersion medium and forming a finely dispersed dispersion stabilizer that is better dispersed. By providing such a dispersion step, the dispersion stabilizing ability as a whole dispersion stabilizer is improved, and the finely divided monomer composition particles are fine powder dispersion stabilizers having an improved dispersion stabilizing ability. It is preferable because it will be protected.

As a dispersing device used in the dispersion step of the dispersion stabilizer, a device such as a high shearing force mixer such as TK homomixer, a piston type high pressure homogenizer or the like is preferably used.

When the liquid temperature during the granulation step in the present invention is adjusted to a temperature at which the monomer composition has a viscosity of 1 to 1,000,000 cps, and preferably 10 to 100,000 cps, the particle size of the monomer composition particles becomes 1 ˜20 μm, and finally a developing toner having a volume average particle size of 1 to 20 μm can be manufactured. As the liquid dispersion medium, usually water or an aqueous medium containing water as a main component is preferably used, and therefore the liquid temperature of the dispersion liquid is preferably adjusted to 20 to 80 ° C., and more preferably 40 to 70 ° C. .

In the above dispersion liquid, it is preferable that the liquid dispersion medium is present in an amount of 200 to 1000 parts with respect to 100 parts of the monomer composition. The dispersion stabilizer is 1 part with respect to 100 parts of the liquid dispersion medium.
It is preferable to use 10 to 10 parts, more preferably 3 to 8 parts.

In the granulation step of the present invention, the monomer composition particles having the same average particle diameter having a weight average particle diameter of about 1 to 20 μm are prepared by the conventional method by using two or more shearing force agitators as described above. 90% to 10% of the case where the monomer composition particles are produced by using the single stirring and mixing apparatus usually used in
It is possible to granulate with the amount of dispersion stabilizer used. Further, as described above, in the present invention, the time required for the granulation step can be made remarkably shorter than the conventional time.

Before subjecting the monomer composition particles formed by the granulation step as described in detail above to the next polymerization step, the monomer composition particles are subjected to classification treatment by a wet classifier or the like, if necessary. May be.

At this time, particles having a desired particle size generated during granulation are separated by a classifier from a particle group having a particle size outside the specified range, and then are gently set under conditions such that coalescence of particles and sedimentation do not occur. It is guided to a polymerization process using a stirrer and is used for a polymerization reaction.

On the other hand, the non-specified coarse particles separated by the classifier are
It is preferable that the particles are reduced to the granulation step, and subsequently subjected to the granulation step to obtain particles having a desired particle size, then sequentially taken out as particles having a desired particle size in the same manner as above, and similarly subjected to the polymerization step.

As a result, the desired particle size of the coarse particles can be achieved without being affected by the size reduction of the monomer composition particles having the desired particle size, and the yield in the granulation step can be improved.

When performing such a classification treatment, it is preferable to use a so-called wet classifier that utilizes the difference in the sedimentation speed of particles in the liquid as the classifier.

As the classification of the wet classifier, there are a sedimentation tank system, a mechanical classifying system, a hydraulic classifying system, a hydrocyclone system, a centrifugal classifying system, an inertial classifying system, and the like. Cyclone method, centrifugal classification method, inertial force classifier method is preferably used,
Among them, the hydrocyclone system, centrifugal classifier system, and inertial force classifier system are particularly preferably used.

Next, the materials constituting the monomer composition will be described.

The polymerizable monomer used in the present invention is a monomer having a CH ₂ ═C group, and specific examples thereof include the following monomers.

That is, styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-methoxystyrene, p-phenylstyrene, p-chlorostyrene, 3,4
-Dichlorostyrene, p-ethylstyrene, 2,4-dimethylstyrene, pn-butylstyrene, p-tert-butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn- Styrene and its derivatives such as nonyl styrene, pn-decyl styrene, pn-dodecyl styrene; ethylene unsaturated monoolefins such as ethylene, propylene, butylene, isobutylene; vinyl chloride, vinylidene chloride, vinyl bromide, Vinyl halides such as vinyl fluoride; Vinyl esters such as vinyl acetate, vinyl propionate and vinyl benzoate; methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, methacrylic acid n-octyl, dodecyl methacrylate, methacryl 2-ethylhexyl acid, stearyl methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate and other α-methylene aliphatic monocarboxylic acid esters; methyl acrylate, ethyl acrylate, n-butyl acrylate , Acrylic acid esters such as isobutyl acrylate, propyl acrylate, n-octyl acrylate, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, phenyl acrylate; maleic acid, maleic acid Half-esters; vinyl ethers such as vinyl methyl ether, vinyl ethyl ether, vinyl isobutyl ether; vinyl such as vinyl methyl ketone, vinyl hexyl ketone, methyl isopropenyl ketone Ton acids; N- vinyl pyrrole, N- vinyl carbazole, N-
N-vinyl compounds such as vinylindole and N-vinylpyrrolidone; vinylnaphthalenes; acrylonitrile,
Acrylic acid or methacrylic acid derivatives such as methacrylonitrile and acrylamide may be used alone or in admixture of two or more.

Among the above-mentioned monomers, it is preferable to use styrene or a styrene derivative alone or in combination with another monomer as a polymerizable monomer in terms of enhancing the toner developing characteristics and durability.

The monomer composition has a fixability in hot pressure roller fixing,
In order to improve the offset resistance, waxes such as paraffin wax, low molecular weight polyolefins such as low molecular weight polyethylene and low molecular weight polypropylene, and the like, having a low softening point compound (preferably a melting point of 60 to 60).
130 ° C.) is preferably added. In this case, the addition amount of the low softening point compound is 1 to 300 parts, and more preferably 4 to 100 parts with respect to 100 parts of the polymerizable monomer.

As the low softening point compound, paraffin, wax, low molecular weight polyolefin, modified wax having an aromatic group, hydrocarbon compound having an alicyclic group, natural wax, a long-chain hydrocarbon chain having 12 or more carbon atoms [CH ₃ CH _{2 11} or CH ₂
Examples thereof include long-chain carboxylic acids having ₁₂ or more aliphatic carbon chains] and esters thereof. Different low softening point compounds may be mixed and used.

As such a low softening point compound, specifically, paraffin wax (manufactured by Nippon Oil Co., Ltd.), paraffin wax (manufactured by Nippon Oil Co., Ltd.), microwax (manufactured by Nippon Oil Co., Ltd.), microcrystalline wax (manufactured by Nippon Seiro Wax Co., Ltd.), hard paraffin. Wax (made by Nippon Seiro) PE-130 (made by Hoechst); Mitsui High Wax 110P, Mitsui High Wax 220P, Mitsui High Wax 660P, Mitsui High Wax 210P, Mitsui High Wax 320P, Mitsui High Wax 410P, Mitsui High Wax 420
P, Highlets-100X, Highlets T-200X, Highlets T-300X, Petrosin 80, Petrosin 100, Petrosin 120, Tack Ace A-100, Tack Ace F-100,
Tack Ace B-60, Modified Wax JC-1141, Modified Wax JC-2130, Modified Wax JC-4020, Modified Wax JC
-1142, modified wax JC-5020 (all manufactured by Mitsui Petrochemical Co., Ltd.); beeswax, carnauba wax, montan wax and the like.

In order to produce a crosslinked polymer in the monomer composition,
Suspension polymerization may be carried out in the presence of the following crosslinking agent. In particular, when a cyclized rubber is not added to the polymer or copolymer in the monomer composition, it is preferable to add a crosslinking agent.

Examples of the crosslinking agent include divinylbenzene, divinylnaphthalene, polyethylene glycol dimethacrylate,
Diethylene glycol diacrylate, triethylene glycol diacrylate, 1,3-butylene glycol dimethacrylate, 1,6-hexane glycol dimethacrylate, neopentyl glycol dimethallylate, dipyropyrene glycol dimethacrylate, polypropylene glycol dimethacrylate, 2, 2'-bis (4-methacryloxydietoxoxyphenyl) propane, 2,2'-
Generally, a cross-linking agent such as bis (4-acryloxydiethoxyphenyl) propane, trimethylolpropane trimethacrylate, trimethylolpropane triacrylate, tetramethylolmethane tetraacrylate, dibromoneopentyl glycol dimethacrylate, diallyl phthalate is appropriately used. be able to.

If the amount of these cross-linking agents used is too large, the toner is less likely to be melted by heat, resulting in poor heat fixability or heat pressure fixability. 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. , It becomes difficult to prevent the offset phenomenon of transferring to the next paper. Therefore, the amount of these cross-linking agents used is based on 100 parts of the polymerizable monomer.
It is preferable to use 0.001 to 15 parts (more preferably 0.1 to 10 parts).

As the colorant contained in the monomer composition, conventionally known dyes, carbon black, and pigments such as grafted carbon black obtained by coating the surface of carbon black with a resin can be used. The colorant is used in an amount of 0.1 to 30 parts based on 100 parts of the polymerizable monomer.

If necessary, a charge control agent and a fluidity modifier may be added (internally 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 complexes of organic compounds having a carboxyl group or a nitrogen-containing group, metal-containing dyes, nigrosine and the like. Examples of the fluidity modifier or the auxiliary agent for cleaning the surface of the latent image carrier (photoreceptor) include colloidal silica and metal salts of fatty acids. 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 the toner particles from agglomerating with each other and improve the fluidity, in order to improve the fluidity such as Teflon fine powder or zinc stearate powder, the fluid such as Teflon fine powder or zinc stearate powder is improved. You may mix a property improving agent.

In order to produce the magnetic polymerized toner, magnetic particles may be added to the monomer composition. In this case, the magnetic particles also serve as (a part or all of) the colorant.

As the magnetic particles that can be used in the manufacturing method of the present invention, a substance that is magnetized when placed in a magnetic field is used, such as iron,
Examples thereof include powders of ferromagnetic metals such as cobalt and nickel, and powders of alloys and compounds such as magnetite, hematite and ferrite. As the magnetic particles, magnetic fine particles having a particle size of 0.05 to 5 μm, preferably 0.1 to 1 μm are usually used, but when a small particle size toner is produced, magnetic particles having a particle size of 0.8 μm or less should be used. Is preferred.

The magnetic particles contained 10 to 60 parts in 100 parts of the monomer composition.
Parts, more preferably 20 to 50 parts.

Further, these magnetic fine particles may be treated with a surface treating agent such as a silane coupling agent or a titanium coupling agent, or an appropriate reactive resin. In this case, depending on the surface area of the magnetic fine particles or the density of hydroxyl groups present on the surface, a treatment amount of 5 parts or less (preferably 0.1 to 3 parts) of the surface treatment agent is usually sufficient for 100 parts of the magnetic fine particles. The dispersibility in the polymerizable monomer is obtained, and the physical properties of the toner are not adversely affected. In addition, the magnetic particles rendered lipophilic by the above treatment and the untreated hydrophilic magnetic particles may be mixed and used.

Next, the polymerization initiator used for the polymerization of the monomer composition composed of the above materials will be described.

In the present invention, the polymerization initiator may be added to the dispersion liquid containing the monomer composition after granulation, but from the viewpoint of uniformly imparting the polymerization initiator to the individual monomer composition particles. It is preferable that the monomer composition is contained in the monomer composition before granulation.

According to the knowledge of the present inventors, when a water-soluble polymerization initiator is used, the resulting 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 preferable to use a substantially water-insoluble polymerization initiator.

Here, in the present invention, the substantially water-insoluble polymerization initiator is one having a solubility of 1 g or less in 100 g of water at room temperature, preferably 0.5 g or less in 100 g of water, particularly It preferably has a low solubility of 0.2 g or less in 100 g of water.

When the polymerization initiator 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 reduces the moisture resistance of the polymerized toner.

Further, the polymerization initiator used in the present invention is preferably soluble in the polymerizable monomer, usually used amount range (for example, 1 to 10 parts of the polymerization initiator to 100 parts of the polymerizable monomer). )
Then, it is preferable that the resin has a solubility characteristic that it is satisfactorily dissolved in the polymerizable monomer.

Examples of such a polymerization initiator include 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 peroxy carbonate, cumene hydroperoxide, 2,4-
Peroxide-based polymerization initiators such as dichlorylbenzoyl peroxide and lauroyl peroxide are exemplified.

In the production method of the present invention, the polymerization initiator preferably has a melting point equal to or lower 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 adjusting the molecular weight and molecular weight distribution of the polymer or for adjusting the reaction time.

The amount of the polymerization initiator used is usually 0.1 to 20 parts, preferably 1 to 10 parts, based on 100 parts of the polymerizable monomer. If the polymerization initiator is less than 0.1 part, it is difficult to uniformly disperse or impart a sufficient amount of the polymerization initiator to each of the monomer composition particles, while if the polymerization initiator exceeds 20 parts, As the molecular weight of the polymerization product decreases, the tendency for the polymerization reaction to occur nonuniformly increases.

In the present invention, the suspension polymerization reaction is usually carried out at a polymerization temperature of 50.
It is carried out at a temperature of not less than 0 ° C, and 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.

After confirming that the monomer composition particles formed by the granulation step have a predetermined particle size, adjust the liquid temperature of the dispersion medium such as an aqueous medium containing the particles (for example, to 55 to 70 ° C). Then, the polymerization reaction proceeds.

Further, when the polymerizable monomer is polymerized by adding an additive comprising a polar polymer having a polar group soluble in the polymerizable monomer, a polar copolymer, a cyclized rubber or the like to the monomer composition. A polymerized toner having preferable characteristics can be obtained.

The polar polymer, polar copolymer or cyclized rubber is preferably added in an amount of 0.5 to 50 parts, more preferably 1 to 40 parts, per 100 parts of the polymerizable monomer. If the polar copolymer etc. is less than 0.5 part,
It is difficult to form a sufficient pseudocapsule structure as described below with the polymerizable monomer, and when the amount of the polymer or the like exceeds 50 parts, the amount of the polymerizable monomer is insufficient, and the properties as a polymerized toner become poor. The tendency to decrease becomes stronger.

A polarizable polymer, a polar copolymer, or a polymerizable monomer composition to which a cyclized rubber has been added is used in the aqueous phase of an aqueous medium in which a fine powder dispersion stabilizer having an opposite charge to the polar copolymer or the like is dispersed. It is preferable to suspend and polymerize. That is, the cationic or anionic polymer, the cationic or anionic copolymer or the anionic cyclized rubber contained in the polymerizable monomer composition is a reversely charged anion dispersed in an aqueous medium. Electrostatically or cationic fine powder dispersion stabilizer is electrostatically attracted to the surface of the toner particles, and the fine powder dispersion stabilizer covers the surface of the particles to prevent unification of the particles and to stabilize the particles. In addition to this, since the added polar polymer, polar copolymer or cyclized rubber gathers on the surface layer of the particle that becomes the toner, the polar polymer or the like forms a kind of shell, and the obtained particles are It has a pseudo capsule structure. The relatively high molecular weight polar polymer, polar copolymer or cyclized rubber collected on the surface layer of the particles has excellent properties such as blocking resistance, developability, charge control property, and abrasion resistance. Is given.

Some of the polar polymers (hereinafter, used to include the polar copolymer and the cyclized rubber) that can be used in the present invention are exemplified below. The polar polymer having a weight average molecular weight of 5,000 to 500,000 as measured by GPC is preferably used because it is well soluble in the polymerizable monomer and has durability.

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

(2) 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 anhydride polymers or copolymers, or copolymers of styrene and these monomers. Further, polyester and cyclized rubber can also be used as the anionic polymer.

On the other hand, as the dispersion stabilizer, either a hydrophilic organic dispersant or a fine powder dispersion stabilizer can be used, but a fine powder dispersion stabilizer is preferably used from the viewpoint of improving the obtained toner moisture resistance.

As the hydrophilic organic dispersant, for example, 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 etc. are mentioned.

As the fine powder dispersion stabilizer, an inorganic fine powder which has a capability of dispersing and stabilizing the monomer composition particles in a liquid medium such as an aqueous medium and is hardly soluble in water is preferably used. The amount of dispersant added to the aqueous medium is 0.5 to 50% based on water.
It is preferable to add (preferably 1 to 20%).

As an anionic fine powder dispersion stabilizer, Aerosil #
200, # 300 (Nippon Aerosil) Nipseal E-220A
Colloidal silica such as (made by Nippon Silica), Fineseal T-32 (made by Tokuyama Soda) and the like can be mentioned.

Examples of the cationic fine powder dispersion stabilizer include aluminum oxide, magnesium oxide, hydrophilic positively charged silica fine powder such as aminoalkyl-modified colloidal silica treated with a coupling agent, and the like.

In addition, in the production method of the present invention, a dispersion stabilizer is necessary, but it is not always necessary to use a dispersion stabilizer having a chargeability opposite to that of the polar polymer in the liquid medium.

Further, in combination with the fine powder dispersion stabilizer, a suitable stabilizer, for example, 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, tricalcium phosphate, talc, barium sulfate, bentonite, aluminum hydroxide, ferric hydroxide, hydroxide Any one or a mixture of two or more of titanium, thorium hydroxide,
You may use it in the range which does not have a bad influence on the manufacturing method of this invention in an aqueous medium.

Further, in order to uniformly disperse the inorganic dispersion stabilizer, a surfactant may be used within a range that does not adversely affect the production method of the present invention. This is to accelerate 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-polyether. Sodium sulfonate, sodium oleate, sodium laurate, sodium caprate, sodium caprylate, sodium caproate, 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. However, it should be noted that when a hydrophilic organic stabilizer or surfactant is used, the moisture resistance of the polymerized toner tends to decrease.

It is also preferable to add a Bronsted acid such as hydrochloric acid to the aqueous medium in order to enhance the ionicity of the polar group of the polar polymer or cyclized rubber in the monomer composition. In particular, adding a Bronsted acid such as hydrochloric acid to the aqueous medium is
It is more preferable for enhancing the effect of the anionic polymer, the anionic copolymer or the cyclized rubber and the dispersant (particularly the cationic fine powder dispersion stabilizer).

After completion of the polymerization reaction, polymerized toner particles are obtained by post-treatment by a usual method. For example, the polymerized toner is obtained by washing the produced polymer particles, removing the dispersion stabilizer, collecting the polymer particles by an appropriate method such as filtration, decantation, centrifugation, etc., and drying.

The polymerized toner obtained by the production method of the present invention can be applied to a known dry electrostatic image developing method without particular limitation. This polymerized toner is obtained by, for example, a two-component developing method such as a cascade method, a magnetic brush method, a microtoning method, a two-component AC bias developing method; a conductive-component developing method, an insulating-component developing method,
One-component developing method using magnetic toner such as jumping developing method; powder cloud method and fur brush method; toner is carried to a developing section by being held on a toner carrier by electrostatic force and used for development. Non-magnetic-component developing method; toner is conveyed to the developing section by the electric field curtain method,
It can be applied to an electric field curtain developing method used for development. The toner obtained by the present invention can be preferably applied to a developing method using a small particle size toner having a weight average particle size of about 2 to 8 μm, which requires a particularly sharp particle size distribution.

Effect of the Invention As described above, according to the present invention, shearing force is applied to a monomer composition in a liquid dispersion medium from two or more high shearing force agitators arranged in the same granulation container, so that the monomer By granulating the composition efficiently and sharply in a sharp particle size distribution,
Provided is a method for producing a toner for developing an electrostatic charge image, which obtains a toner having excellent characteristics.

Examples Hereinafter, the present invention will be described more specifically based on Examples.

Example 1 Using an attritor, the above polymerizable monomer mixture
Monomer composition by mixing at 30 ℃ (viscosity at 60 ℃ 300 cp
s) was prepared. Next, 5 parts of amino-modified silica (100 parts by weight of Aerosil # 200 manufactured by Nippon Aerosil Co., Ltd., was reacted with 5 parts by weight of aminopropyltriethoxysilane),
The monomer composition prepared above was added to a 20-liter stainless steel container (cylindrical shape, bottom diameter 35 cm) containing 600 parts of distilled water and 20 parts of 1/10 N hydrochloric acid, and the turbine at 60 ° C. Using two TK homomixers (made by Tokushu Kika Kogyo)
Granulated by stirring at 10,000 rpm for 10 minutes. During this granulation,
The TK homomixers (2 pieces) were placed in parallel with each other at a distance of 9 cm at symmetrical positions with respect to the center of the bottom surface of the stainless steel container.

After granulation, the monomer composition was polymerized under the conditions of 60 ° C. for 10 hours using a paddle stirring blade.

The polymerized product obtained above was cooled and dehydrated, then washed with a sodium hydroxide solution, dehydrated and dried to obtain a polymerized toner.

When the viscosity of the obtained toner was measured with a Coulter counter (aperture 100 μm), the volume average particle diameter of the toner was 5.2 μm, and the volume percentage of fine powder of 2.52 μm or less was 6%, and the volume percentage of coarse powder of 8.0 μm or more. Had a very narrow particle size distribution of 3%.

Example 2 Using an attritor, the above polymerizable monomer mixture
A monomer composition was prepared by mixing at 30 ° C.

Amino-modified silica (Aerosil # 20 manufactured by Nippon Aerosil Co., Ltd.)
100 parts by weight of 0 was reacted with 5 parts by weight of aminopropyltriethoxysilane) 6 parts, 600 parts of distilled water, 1 / 10N
The monomer composition prepared above was added to a stainless steel container having a volume of 20 liters containing 22 parts of hydrochloric acid, and the same procedure as in Example 1 was repeated.
℃, using two TK homomixer (made by Tokushu Kika Kogyo)
After granulating with stirring at 10,000 rpm for 30 minutes, polymerization was carried out in the same manner as in Example 1 at 60 ° C. for 10 hours.

The obtained polymerized product was cooled, dehydrated, washed with a sodium hydroxide solution, dehydrated, and dried to obtain a polymerized toner.

When the viscosity of the obtained toner was measured with a Coulter (aperture 50 μm), the volume average particle diameter of the toner was 4.5 μm, the volume percentage of fine powder of 2.52 μm or less was 3%, and the volume percentage of coarse powder of 8.0 μm or more. Is 3%
The particle size distribution was extremely narrow.

Example 3 Using an attritor, the above polymerizable monomer mixture
Monomer composition by mixing at 30 ℃ (viscosity at 60 ℃ 300 cp
s) was prepared.

Next, after granulating in the same manner as in Example 1 except that 5 parts of colloidal silica (Aerosil # 200 manufactured by Nippon Aerosil) and 600 parts of water were used, 60 ° C. and 10
Polymerization was carried out under the condition of time.

The obtained polymerized product was cooled and dehydrated, then washed with a sodium hydroxide solution, dehydrated and dried to obtain a polymerized toner.

When the particle size of the obtained toner is measured with a Coulter counter (aperture 100 μm), the volume average particle size is
The particle size distribution was 5.2 μm, and the volume percentage of fine powder of 2.52 μm or less was 6%, and the volume percentage of coarse powder of 8.0 μm or more was 3%, showing an extremely narrow particle size distribution.

Example 4 ^* Isopropyltriisostearoyl titanate,
(Ajinomoto Co., Inc.) Planeact KR-TTS The above polymerizable monomer mixture was mixed with an attritor 30
Monomer composition by mixing at ℃ (viscosity 100 cps at 80 ℃)
Was prepared.

Next, 6 parts of amino-modified silica (100 parts by weight of Nippon Aerosil Aerosil # 200 reacted with 5 parts by weight of aminopropyltriethoxysilane), 600 parts of distilled water, and 20 parts of 1 / 10N hydrochloric acid were added. Add the monomer composition prepared above to a stainless steel container with a capacity of 20 liters.
Example 1 using two homomixers (made by Tokushu Kika Kogyo)
After granulating in the same manner as above, polymerization was performed.

The obtained polymerizable product was cooled and dehydrated, then washed with a sodium hydroxide solution, dehydrated, and dried to obtain a polymerized toner.

When the viscosity of the obtained toner was measured with a Coulter counter (aperture 100 μm), the volume average particle diameter was
The particle size distribution was 5.5 μm, the volume percentage of fine powder of 2.52 μm or less was 6%, and the volume percentage of coarse powder of 8.0 μm or more was 3%, showing a very narrow particle size distribution.

0.4 part of hydrophobic silica (R-972 manufactured by Aerozir Co., Ltd.) was externally added to 100 parts of the polymerized toner thus obtained, and then an image was obtained using a commercially available copying machine (NP-250 manufactured by Canon Inc.). As a result of a formation test, a good image was obtained with the image density and the image quality.

Comparative Example 1 A toner was obtained by granulating and then polymerizing in the same manner as in Example 1 except that one TK homomixer was used as a stirrer.

In this polymerized toner, coarse powder of 16 μm or more was observed, and the toner had a wider particle size distribution than the toner of Example 1.

Comparative Example 2 A toner was obtained by granulating and polymerizing in the same manner as in Example 4 except that one TK homomixer was used as the stirring means and the granulating time was 60 minutes.

When this toner was observed under an optical microscope (400 parts), a large number of transparent particles (particles containing no colorant) were observed.

After classifying this toner to an average particle size of 5.5 μm,
To 100 parts of this classified toner, hydrophobic silica (R-97
When 0.4 part of 2) was externally added and an image forming test was conducted using NP-250 as in Example 4, only a rough image with low image quality was obtained.

[Brief description of drawings]

FIG. 1 is a schematic side sectional view showing an embodiment of a high shear stirring device used in the present invention, and FIGS. 2 (a) and 2 (b) are schematic perspective views showing an embodiment of a turbine used in the stirring device,
3 (a) and 3 (b) are schematic cross-sectional views showing an embodiment in which a turbine is arranged in a stator, and FIGS. 4 (a), 4 (b) and 4 (c) are arrangements of two or more stirring devices. FIG. 3 is a schematic side cross-sectional view or schematic perspective view showing FIG. DESCRIPTION OF SYMBOLS 1 ... High shear stirring device 2 ... Turbine 3 ... Stator 4 ... Turbine bearing 5 ... Bottom plate 6 ... Granulation container 7 ... Agitator Representative drawing: FIG. 4 (a)

Front page continuation (72) Inventor Hitoshi Kanda 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (56) Reference JP-A-60-120986 (JP, A) JP-A-53-17735 ( JP, A)

Claims (1)

[Claims] 1. A granulation container containing a dispersion stabilizer, a monomer composition containing at least a polymerizable monomer and a colorant,
And when granulating by dispersing in a liquid dispersion medium that is substantially incompatible with the above polymerizable monomer; granulating using two or more high shearing force agitators arranged in the same granulating vessel A method for producing a toner for developing an electrostatic charge image, comprising: