JPH09114135A - Manufacture of electrophotographic toner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of the toner having the grain size distribution of grains sufficiently sharp for use as the toner and excellent lot reproducibility of the average grain size. SOLUTION: A stirring device has a rotary shaft fitted with main stirring blades and auxiliary stirring blades in a stirring tank. The terminals of the main stirring blades are separated from the inner wall side face of the stirring tank to generate a rising liquid flow at the time of stirring, and the auxiliary stirring blades have scrapers inclined vertically or in the raking direction as rotated on the inner wall side of the stirring tank and paddles connected to the scrapers and inclined vertically or in the depressing direction as rotated. An aqueous medium is added and mixed into the organic solvent solution of a mixture constituted of a colorant and a binding resin made of a water- nonsoluble resin dispersible in water as the principal constituent for phase inversion and emulsification to form colored resin fine grains, then the organic solvent is removed, and the spherical colored resin fine grains dispersed in the aqueous medium are taken out as dry powder.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a dry toner which employs a phase inversion emulsification formula and is used for developing electrophotographic copying machines, printers, faxes and the like.

[0002]

Spherical colored fine particles obtained by mixing an organic solvent solution of a mixture of a binder resin and a colorant as essential components with an aqueous medium, emulsifying the mixture, and then removing the solvent in the dispersion. As a manufacturing method of, for example, JP-B-61-28
No. 688 and Japanese Patent Application Laid-Open No. 4-303849, a method of using an emulsifier, and an emulsifier using a self-water-dispersible resin described in Japanese Patent Application Laid-Open No. 3-221137 and 5-66600 as a binder resin. There are known methods such as not using.

In the formation of spherical colored fine particles utilizing such an emulsification phenomenon, if the resin composition and the organic solvent composition are the same, the stirring and mixing method of the organic solvent solution and the aqueous medium is the particle size distribution of the fine particles. It has a great influence on the lot reproducibility of particle size.

As a stirring / mixing device that can be used for these, conventionally known devices have been used. Examples of stirring blades used for them are anchor blades, turbine blades, hoodler blades, Maxblend blades (Sumitomo Heavy Industries, Ltd.), full zone blades (Shinko Pantech Co., Ltd.), etc. -As a mixing device, there is a homomixer (Tokuki Kika Kogyo Co., Ltd.) and the like.

[0005]

However, in the method for producing spherical toner particles using the above stirring / mixing device in the phase inversion emulsification step, the particle size distribution of the obtained particles is broad and the average of the particles is large. Large fluctuation in particle size due to lot. Therefore, for example, in order to put it into practical use in the toner field in which control of charging property is strictly required, a step of classifying the obtained spherical toner particles to make the particle size distribution sharper is separately performed. It was essential to have it. Therefore, there is a problem that the yield of toner particles falling within a required predetermined particle size distribution is reduced, resulting in an increase in manufacturing cost and a decrease in productivity.

In the present invention, a particle size distribution of particles is used as a toner by using a special stirring device, whether or not an emulsifier or dispersion stabilizer is used in the phase inversion emulsification step. It is an object of the present invention to provide a method which is sufficiently sharp and has excellent lot reproducibility of the average particle size.

[0007]

Means for Solving the Problems As a result of a detailed study of the role and flow of each part of the stirring blade, the present inventors have found that a multi-stage stirring blade having a specific structure is provided in the stirring tank to obtain a particle size distribution. The inventors have found that sharp spherical toner particles can be efficiently and reproducibly manufactured, and have completed the present invention.

That is, according to the present invention, in a stirrer having a rotating shaft in which a main stirring blade and an auxiliary stirring blade are mounted in a stirring tank, the main stirring blade is connected to the end of the stirring shaft so as to generate an ascending liquid flow during stirring. It is separated from the side surface of the inner wall of the stirring tank and is located at the lowest stage of the central axis. On the other hand, the auxiliary stirring blade stirs the scraper inclined vertically or in the direction of scraping with its rotation. It is provided on the inner wall side of the tank and has a paddle that is connected to the scraper and is inclined vertically or in a direction to push it down as it is rotated. The stirring device is characterized in that it is installed so as to cause a phase shift in the direction opposite to the direction of rotation of the rotating shaft with respect to the lower end of the stirring blade of the Dispersible water-insoluble tree An organic solvent solution of a mixture consisting of a binder resin consisting of an essential component and a phase inversion emulsion by adding and mixing an aqueous medium, or a colorant, and a binder resin consisting of a water-insoluble resin as an essential component. An aqueous medium containing an emulsifier and / or a dispersion stabilizer is added to and mixed with the organic solvent solution to form phase inversion emulsification to form colored resin fine particles, and then the organic solvent is removed to obtain a spherical shape dispersed in the aqueous medium. The present invention provides a method for producing an electrophotographic toner by taking out colored resin fine particles as a dry powder.

Hereinafter, "an organic solvent solution of a mixture containing a colorant and a binder resin consisting of a water-insoluble resin that can disperse in water by itself" as an essential component and "from the colorant and the water-insoluble resin" An organic solvent solution containing a binding resin that is an essential component together, and simply referred to as an organic solvent solution (A), together with an "aqueous medium" and an "aqueous medium containing an emulsifier and / or a dispersion stabilizer", It is simply referred to as an aqueous medium (B). The aqueous medium is water or a liquid medium containing water as a main component.

In this agitator, the creativity for simultaneously improving both the shear mixing property and the total circulation mixing property is the basis. That is, in the stirring in this stirring device, the liquid in the stirring tank becomes a discharge flow from the bottom of the tank generated by the main stirring blades, rises along the wall surface of the tank, and then descends near the central axis. Simultaneously with formation, shear mixing is performed by a scraper having an auxiliary stirring blade without canceling the circulation.

First, in the main stirring blade of the present stirring device, the end of the main stirring blade is separated from the side surface of the inner wall of the stirring tank so as to generate an ascending liquid flow at the time of stirring. It produces a strong ejection force that is the starting point.

Here, the distance between the end of the main stirring blade and the side surface of the inner wall of the stirring tank may be so large as to cause an ascending liquid flow at the time of stirring. Above all, a strong circulating flow in the tank is obtained. Therefore, it is preferable that the ratio of the inner diameter of the stirring tank to the length passing through the central axis of the stirring blade is 0.5 to 0.9.

The shape is not particularly limited, but a wide paddle is preferable from the viewpoint of excellent discharge force. Further, the installation location is at the lowest stage of the central axis, but it is preferable that it is provided along the wall surface of the bottom of the tank, because it greatly contributes to the generation of the rising liquid flow.

The auxiliary stirring blade in the present stirring device does not cancel the rising liquid flow generated by the main stirring blade, but rather contributes to the overall circulation mixing property in the tank, and at the same time, the outer end of the blade and the tank are The gap is reduced, scraping and shear mixing are performed to prevent adhesion to the tank wall, etc., and the scraper is inclined vertically or in the direction of scraping with its rotation.
The pad is provided on the inner wall side of the stirring tank, and is also connected to the scraper and has a paddle that is inclined vertically or in a direction of pushing down with rotation.

Although the number of the auxiliary stirring blades may be one, it is preferable that the number of auxiliary stirring blades is plural from the viewpoint of excellent shear mixing property and circulation mixing property. For example, the number thereof is preferably 2 to 5 stages. .

With respect to the shape of the auxiliary stirring blade, both the scraper portion at the outer end and the paddle portion supporting it inside may be vertical, but in the direction in which the scraper portion scrapes up as it rotates, and It is more preferable that the paddle portion is inclined in the direction of scraping with rotation. Particularly, in the region where the liquid viscosity is low and the inertial flow is dominant, the inclined shape shows a better mixing property.

Further, in a plurality of stirring blades composed of a main stirring blade and an auxiliary stirring blade, the stirring blades vertically adjacent to each other are such that the upper end of the lower stirring blade is the rotation direction of the rotating shaft with respect to the lower end of the upper stirring blade. Since they are installed so as to cause a phase shift in the opposite direction, the overall circulation and mixing property in the stirring tank becomes remarkably excellent. In particular, in the region where the liquid viscosity is high and it is difficult for the inertial force to propagate, it shows an extremely large contribution to the overall circulation and mixing property.

That is, for example, when the phase difference between the stirring blades is set to 0 degree, the phenomenon that the entire liquid in the tank makes one solid rotation and the mixing property is remarkably deteriorated easily occurs.

In detail, the action of the circulation mixing property caused by the phase difference between the stirring blades in the present stirring device is described. That is, the rotating stirring blade always has a positive pressure on its front surface and a rear stirring surface. Negative pressure is generated. At this time, if the upper ends of the adjoining lower stirring blades exist so as to be out of phase with each other in the direction opposite to the rotation direction, that is, to be behind, the front surface of the lower stirring blade and the rear surface of the upper stirring blade A pressure gradient occurs between them, and the liquid can be more efficiently transported to the upper part near the wall surface of the stirring tank.

Of course, it is expected that this phase difference has a canceling effect on the downward flow near the central axis, but the paddle-to-paddle spacing near the central axis should be the same as that between scrapers. It's much wider than that and not a problem.

What is noteworthy here is that, when stirring a high-viscosity liquid, the pressure can easily propagate even though it is difficult for the inertial force to propagate under high liquid viscosity. As a result, the agitator of the present invention can have excellent overall circulation and mixing properties from the low viscosity region to the high viscosity region.

The phase difference is not particularly limited as long as adjacent upper and lower stirring blades are in a position having a relationship of upper end stirring blade lower end leading and lower stirring blade rear upper end row. Is 10 to 70 degrees, more preferably,
It is preferably in the range of 30 to 60 degrees.

Particularly, it is preferable that the upper blade and the lower blade are close to each other in the scraper section because the effect of the total circulation mixing property is great.

Further, in the present stirring device, it is preferable that a baffle plate is provided on the inner wall of the stirring tank in the vicinity of the scraper. This baffle diverts the flow in the circumferential direction to the flow in the axial direction in the low-viscosity region, and in the high-viscosity region, partial shear mixing with the scraper, or circulation of the liquid in the tank. It plays an important role for prevention purposes. In order to enhance this effect, it is preferable that the baffle plates are provided at a plurality of positions along the circumferential direction of the cylindrical inner wall.

The shape is not particularly limited, but it must be designed so as not to contact the main stirring blade and the auxiliary stirring blade. For example, a T-shaped plate shape as shown in FIG. The following are listed. Especially, this baffle is T
When the baffle plate is in the shape of a template, it is preferable that the baffle plate is further inclined in a direction to push up the rotating liquid flow.

The stirring tank has a cylindrical shape, and
As described above, it is preferable that baffle plates are provided at a plurality of positions along the circumferential direction of the inner wall.

In the step of forming spherical colored fine particles using the principle of phase inversion emulsification, as the aqueous medium (B) is added to the organic solvent solution (A), the phase inversion point (from W / O Viscosity increases until it reaches the point where it changes to O / W,
Immediately after passing the phase inversion point, a sharp decrease in viscosity occurs, so
This stirring device having excellent overall mixing properties from the low viscosity region to the high viscosity region is particularly suitable.

According to the knowledge of the present inventors, regarding the particle size control in the formation of spherical resin fine particles utilizing the emulsification phenomenon, in the case of toner particles of submicron order, the particle size control is relatively easy and the particle size distribution is Although it is easy to obtain sharp particles of 2 to 20 like the existing toner particles for electrophotography.
In the case of particles of about μm, the particle size distribution becomes broad,
And it is known that lot reproducibility of particle size is poor,
In this micron order, the effect of the present invention is particularly remarkable.

If the stirrer of the present invention is used, the mixing conditions of the organic solvent solution (A) and the aqueous medium (B), the kind and amount of the organic solvent (resin concentration), the emulsifier and / or the emulsifier /
Alternatively, when using a dispersion stabilizer, the type and amount thereof, which is a suitable binder resin used in the present invention, when using a self-water-dispersible resin, the type and amount of the neutralizing agent (neutralization ratio ) And the like can be selected to produce spherical toner particles having an arbitrary average particle diameter and a sharp particle size distribution with good lot reproducibility.

In this case, generally, as the number of revolutions of stirring is increased, when the emulsifier and / or the dispersion stabilizer is used, the amount thereof is increased, and when the self-water-dispersible resin is used, it is moderate. The average particle size of the obtained spherical colored fine particles tends to become smaller as the amount of the solvating agent increases.

The phase inversion emulsification can be carried out by mixing the organic solvent solution (A) and the aqueous medium (B).
In the present invention, phase inversion emulsification is carried out by a method of adding the aqueous medium (B) to the organic solvent solution (A), which is more preferable in terms of the effect of the present invention.

For the method of adding the aqueous medium (B) to the organic solvent solution (A), refer to "Amount of aqueous medium required for phase inversion emulsification".
All of the above can be added at a constant rate with stirring or at an arbitrary rate (including changing the rate of addition in the middle) to obtain colored fine particles, but the amount of the aqueous medium required for phase inversion emulsification can be obtained in advance. 50% by weight or more of
Adding the rest of the aqueous medium at a constant rate over 0.5 hours and carefully passing through the phase inversion point not only improves productivity, but also makes the particle size distribution of the obtained colored resin fine particles sharper. And the lot reproducibility is improved.

In this case, of the "amount of aqueous medium required for phase inversion emulsification", the amount of aqueous medium charged at one time is 50 to 95% by weight, preferably 55% by weight of the amount of aqueous medium required for phase inversion emulsification. It is preferable to add the remaining 20 to 45% by weight of the aqueous medium at a constant rate of about 10 to 40% by weight per hour. Practically, this water addition time should be selected within 0.5 to 4 hours, which is more efficient than adding the total amount of the aqueous medium at a constant rate over a long period of time. is there.

The above-mentioned "amount of aqueous medium required for phase inversion emulsification" means a spherical colored resin fine particle having no mechanical voids (voids) due to phase inversion from W / O to O / W. It is the minimum amount of aqueous medium required to form a dispersion liquid, which is determined by the resin composition, organic solvent composition, emulsifier, neutralizing agent, and the like. After the addition of the "amount of aqueous medium required for phase inversion emulsification" is completed, it is preferable to additionally add an excessive aqueous medium in order to prevent the aggregation of fine particles in the subsequent step.

Regarding the temperature of the solution when forming the spherical colored resin fine particles by phase inversion emulsification, in order to prevent the produced fine particles from aggregating in the solution, the temperature is higher than the glass transition temperature (Tg) of the binder resin. It is suitable to lower the temperature by about 10 ° C or more.

Since the Tg of a toner is generally around 60 ° C. due to restrictions such as the heat resistant storage stability of the toner and the fixing temperature, the solution temperature during emulsification according to the present invention is preferably about 50 ° C. or lower. As for the lower limit of the temperature, spherical fine particles can be formed by emulsification within the range of the freezing temperature of the solution or higher, but it is practically preferable to select the temperature from about 5 ° C or higher.

The binding resin used in the present invention includes:
It is not particularly limited as long as it is soluble in the organic solvent used when preparing the organic solvent solution (A), and is, for example, a water-insoluble substance having “self-water dispersibility” that can disperse in an aqueous medium by itself. There are resins and water-insoluble resins that can be dispersed in an aqueous medium only by using an emulsifier or a dispersion stabilizer without being dispersed in the aqueous medium itself.

As such a water-insoluble resin for toner, for example, styrene resin, acrylic resin, styrene acrylic resin, polyester resin, polyurethane resin or epoxy resin is suitable.

The above-mentioned resin has a molecular weight of a level required to develop sufficient mechanical strength, usually 3,000 to 300,000 as a weight average molecular weight, and acrylic resin has 10,000 to 300,000, and
In the DSC measurement, the glass transition temperature (Tg) is 50 to
A temperature of 100 ° C. is preferable.

Among the above-mentioned binder resins, the self-water-dispersible resin preferably used in the present invention is a resin containing a functional group capable of becoming an anionic or cationic hydrophilic group by neutralization. A resin which is capable of forming a stable aqueous dispersion under the action of an aqueous medium, in which some or all of functional groups capable of forming properties are neutralized with a base or an acid, without using an emulsifier or a dispersion stabilizer.

In the case of anionic resins, examples of the functional group that can be converted into a hydrophilic group by neutralization include so-called acidic groups such as a carboxyl group, a phosphoric acid group and a sulfonic acid group. In this case, for example, so-called basic groups such as dimethylamino group and diethylamino group can be mentioned. Examples of resins containing these functional groups include styrene resins, acrylic resins, styrene acrylic resins, polyester resins, polyurethane resins,
Epoxy resins and the like can be mentioned.

Taking a carboxy group-containing anionic resin that can become a hydrophilic group by neutralization as an example, the content of the carboxyl group that can become an anionic hydrophilic group by neutralization in the resin is particularly limited. Acid value 4
About 0 or more is preferable because particles can be easily formed by the phase inversion emulsification method. Particularly preferably, the acid value is 50 to 150.

The basic neutralizing agent used for these is not particularly limited, but examples thereof include inorganic alkalis such as caustic soda, potassium hydroxide, lithium hydroxide, calcium hydroxide, sodium carbonate and ammonia, and diethylamine, Examples include organic bases such as triethylamine and isopropylamine.

The acidic neutralizing agent is not particularly limited, and examples thereof include inorganic acids such as hydrochloric acid, sulfuric acid and phosphoric acid, and organic acids such as formic acid, acetic acid and propionic acid.

In the present invention, when a non-water-soluble resin which does not disperse in water as described above, that is, does not have self-water dispersibility, is used as the non-water-soluble resin which is a binding resin, a resin solution is used. It is necessary to add emulsifiers and / or dispersion stabilizers to the aqueous medium that is mixed with and / or with it.

The dispersion stabilizer is preferably a water-soluble polymer compound, and examples thereof include polyvinyl alcohol, polyvinylpyrrolidone, hydroxyethyl cellulose, carboxymethyl cellulose and the like. Examples of the emulsifier include various nonionic surfactants such as polyoxyethylene alkylphenol ether, and various anionic or cationic surfactants such as sodium alkylbenzenesulfonate. Of course, two or more kinds of emulsifiers may be used in combination, two or more kinds of dispersion stabilizers may be used in combination, or an emulsifier and a dispersion stabilizer may be used in combination. It is common to use an emulsifier in combination.

In this case, when an emulsifying agent or a dispersion stabilizer is used, its concentration in the aqueous medium is suitably about 0.5 to 3% by weight.

Compared to the practice of the present invention by combining an emulsifier and / or a dispersion stabilizer with a water-insoluble resin that does not disperse in water by itself, the resin that can be dispersed in water is neutralized by neutralization. The self-water dispersible resin, which can be dispersed in water by itself, is less likely to cause disadvantages such as moisture absorption and bleeding due to the emulsifier and the dispersion stabilizer, and as described later for avoiding the disadvantages. This is more preferable because it is possible to omit a special washing step and the productivity is improved.

Examples of the organic solvent used for dissolving the binder resin and dispersing the colorant in the present invention include hydrocarbons such as pentane, hexane, heptane, benzene, toluene, xylene, cyclohexane and petroleum ether. Halogenated hydrocarbons such as methylene chloride, chloroform, dichloroethane, dichloroethylene, trichloroethane, trichloroethylene, carbon tetrachloride; alcohols such as methanol, ethanol, isopropyl alcohol, butanol; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone Esters such as ethyl acetate and butyl acetate, and the like;
You may use these 2 or more types in mixture.

The colorant used in the present invention is not particularly limited, but it is conventionally known as a toner material such as carbon black, copper phthalocyanine pigment, azo pigment, benzidine pigment, quinacridone pigment, magnetic powder and the like. Various kinds of pigments and dyes. The content of the colorant is preferably 3 to 15% by weight based on the binder resin.

In the toner of the present invention, if necessary, a charge control agent such as a chromium-containing metal complex salt dye, nigrosine, waxes (release agent) such as polyethylene wax, polypropylene wax, paraffin wax, and silicone. Add 0.1 to 1 of additives such as oil to the binder resin
You may contain about 0 weight %.

Regarding the addition of these additives and the colorant, after adding them to the organic solvent solution of the binder resin, they are sufficiently pulverized using a general mixing / dispersing machine such as a ball mill or a continuous bead mill.・ Methods such as mixing may be used.

The aqueous dispersion of spherical colored resin fine particles thus obtained by phase inversion emulsification is generally used for electrophotographic powders by removing the aqueous medium, then filtering and drying by means such as filtration. It can be used as a body toner. The spherical colored resin fine particles obtained by using the emulsifier and the dispersion stabilizer are preferably washed more thoroughly before use.

In removing the aqueous medium in the aqueous dispersion of the spherical colored resin fine particles, the organic solvent is removed in advance and then the water is removed. It is preferable because it is small.

Of course, as the binding resin, a self-water-dispersible resin obtained by neutralizing a water-insoluble resin having an acidic group, which becomes an anionic hydrophilic group by neutralization, with a basic neutralizing agent. In the case of using the present invention to obtain spherical resin fine particles using the organic solvent, the functional group based on the neutralized hydrophilic group obtained on the surface of the fine particles with the acidic neutralizing agent is used. It is preferable to employ a method in which the hydrophilicity of the fine particles themselves is further reduced by carrying out a reverse neutralization treatment in which the water is removed, and then water is removed, followed by filtration and drying.

Any known and commonly used method can be adopted for the above-mentioned drying. For example, it may be dried under atmospheric pressure or reduced pressure at a temperature at which the toner particles are not thermally fused or aggregated, or may be freeze-dried. Can be mentioned. There is also a method of simultaneously separating and drying toner particles from an aqueous medium using a spray dryer or the like.

When the spherical colored resin fine particles obtained in the present invention are used as powder, the drying condition is preferably a temperature at which the fine particles do not fuse or aggregate.

The toner particles obtained in the present invention have a binder resin and a colorant as essential components. When the colorant is a pigment, the pigment particles are included in the matrix of the binder resin. Or, it has a shape in which it is uniformly dispersed.

As the particle size of the toner powder of the present invention, any size can be selected within a practical level as a toner. The volume average particle diameter is 2 to 200 μm, preferably 4 to 1 from the viewpoint of matching with the current machine.
The range of 2 μm is preferable.

The dry powder toner composed of the spherical colored resin fine particles thus obtained can be used as it is as a toner for electrophotography, but inorganic fine particles such as hydrophobic silica, titanium oxide and aluminum oxide, and various polymer fine particles, etc. It is preferable to select an appropriate one from the above and use it as a toner after externally treating it. These inorganic fine particles and polymer fine particles may be used in combination of a relatively large particle diameter and a relatively small particle diameter.

The electrophotographic toner of the present invention thus obtained can be used as a non-magnetic one-component toner or a magnetic one-component toner, or as a two-component developer in combination with a carrier. Good characteristics can be obtained as a two-component developer.

As the carrier, any known carrier can be used, and examples thereof include iron, nickel, copper, zinc,
Powders of metals such as cobalt, manganese, chromium, rare earths and alloys or oxides thereof, surface-treated glass, silica and the like can be used. Needless to say, a ferrite carrier or magnetite carrier coated with an acrylic resin, a fluororesin and / or a silicone resin can be used. The carrier has a particle size of, for example, about 20 to 200 microns.

When a two-component electrostatic image developer is obtained from the toner obtained in the present invention and a carrier, for example, the toner is mixed at a ratio of 1 to 15 parts by weight of toner per 100 parts by weight of carrier. You can use it.

[0064]

BEST MODE FOR CARRYING OUT THE INVENTION Next, an embodiment of the present invention will be described by taking a preferred embodiment as an example. Styrene and (meth) acrylic acid as essential components, acid value 50-150, weight average molecular weight 1
0000-300000, glass transition temperature 50-100
℃, with a basic neutralizing agent, to obtain a styrene resin that can be self-dispersible in water, a more hydrophobic organic solvent that dissolves it, a more hydrophilic organic solvent that dissolves it, By mixing with a basic neutralizing agent, a water-insoluble resin as a binder resin is a self-water-dispersible resin, and an organic solvent solution is obtained.

This organic solvent solution is stirred in a stirrer having a rotating shaft in which a main stirring blade and an auxiliary stirring blade are mounted in a stirring tank, and the main stirring blade has its end so as to generate an ascending liquid flow during stirring. And the side surface of the inner wall of the stirring tank are separated, and
The auxiliary stirring blade is located at the lowest stage of the central axis, and the auxiliary stirring blade has a scraper that is vertical or inclined in the direction of scraping with its rotation, on the inner wall side of the stirring tank, and It has a paddle that is connected and tilted vertically or in a direction that pushes it down as it rotates. It is installed in a stirrer, which is installed so that a phase shift occurs in the direction opposite to the direction, and the liquid temperature in the tank is adjusted to 10 to 50 ° C.
The temperature is set so that it is in a stirring state.

Then, the total amount of the aqueous medium required for the phase inversion emulsification is obtained in advance, and the liquid temperature in the tank of the stirrer is made to be the same, and 50% by weight or more of the total amount is stirred at once at once. Add to this condition and mix. The remaining aqueous medium of less than 50% by weight kept at the liquid temperature in the tank was added dropwise over 0.5 hours to carry out phase inversion emulsification to obtain an aqueous dispersion of spherical colored resin fine particles, and further add water. .

From this dispersion, the organic solvent is removed, and an inorganic acid aqueous solution is used to restore the carboxyl groups present on the surface of the spherical colored resin fine particles and neutralized with the basic neutralizing agent to the original carboxyl groups. After reverse neutralization, the fine particles are filtered and washed with water, and then dried under the condition that the fine particles do not fuse with each other, and the average particle size is 2 to 50 μm, which is self-dispersible in water by neutralization. A spherical colored resin fine particle powder is obtained in which smaller pigment particles are included in the binder resin matrix of the organic resin and dispersed therein. The fine particles obtained here have a very sharp particle size distribution, and a very small amount of loss is required as compared with the prior art, even if the particles are not separately classified or classified. Therefore, the productivity is also good.

0.05 based on the weight of the obtained toner powder
To 2% by weight of hydrophobic inorganic fine particles having an average primary particle diameter of 5 to 30 nm are mixed by a mixer to obtain externally added toner particle powder.

Next, 3 to 10 parts by weight of the powder is added and mixed per 100 parts by weight of the carrier to prepare a two-component type electrophotographic two-component dry developer.

[0070]

The present invention will be described more specifically below with reference to examples of the present invention. However, the invention is not limited to these examples. The “parts” are all based on weight.

Example 1 Methyl ethyl ketone 700
Parts were placed in a reaction vessel and heated to 80 ° C. Then
Acrylic acid 77 parts, styrene 600 parts, acrylic acid 2-
Ethylhexyl 143 parts, methyl methacrylate 180
Part, 7 parts of "Perbutyl O" (Nippon Oil & Fat Products Co., Ltd.) was added dropwise over about 2 hours. After the dropping of the above mixture, 2 parts of "perbutyl O" was added to the reaction solution every 4 hours, and the reaction was continued at 80 ° C for 24 hours. The reaction was performed under a nitrogen atmosphere. After the reaction was completed, a solution of an anionic synthetic resin having a weight average molecular weight of about 48,000 and an acid value of about 60 was obtained.

1000 parts of this resin solution, 127 parts of methyl ethyl ketone and 59 parts of "Elftex 8" (Carbon Black manufactured by Cabot) were added to "Eiger Motor Mill M-250 VSE-EXJ" (manufactured by Eiger).
Were mixed to prepare a mill base.

700 parts of this mill base was placed in a cylindrical reactor having an internal volume of 2 liters having a stirring device as shown in FIG. 1, and 112 parts and 1 part of isopropyl alcohol were added.
Charge 32 parts of normal caustic soda solution.

In this agitator, a central shaft 1 is installed at the center of the tank, and two wide paddles 2 are attached to the lower end of the shaft along the bottom wall surface of the tank. 3 is a paddle having a scraper 4 at its tip, both the paddle and the scraper are vertical, and the lower end of the upper scraper and the lower scraper
An example is shown in which the phase difference at the upper end of the optical path is 45 degrees, and the upper side is attached in the upper direction with respect to the rotation direction. 5 is a baffle,
It is installed between each multi-stage blade and at multiple points along the circumferential direction.

While stirring the stirring blade of the present reactor, which was charged with the mill base, the additional solvent and the base, at a rotation speed of 300 rpm, 213 parts of water was added thereto at one time. After the liquid temperature in the reaction vessel was set to 35 ° C., 174 parts of water which was also at 35 ° C. was added at a constant rate of 59 parts per hour for 3 hours to carry out phase inversion emulsification.

Next, 420 parts of water was added at one time, and the mixture was sufficiently stirred and mixed, and then the organic solvent was removed by distillation under reduced pressure, a 1N aqueous hydrochloric acid solution was added to adjust the pH to about 3, and filtration,
After washing with water, the wet cake was dried to obtain a spherical colored resin fine particle powder containing a non-water-soluble resin capable of self-water dispersion by neutralization as a binder resin.

The spherical colored resin fine particles had a weight average particle diameter of 8.0 μm as measured by a Coulter counter.
Dp / Dn (volume average particle diameter / number average particle diameter) is 1.12.
It had a very sharp particle size distribution. Furthermore, the particle ratio of 4 μm or less is 1.8%, and the particle ratio is 16 μm.
The above particle ratio was 0%, which was very good. Further, when the fine particles are observed by SEM (scanning electron microscope), they are true spheres. When the cross section of the fine particles embedded with resin and cut by a microtome is observed by TEM (transmission electron microscope),
The carbon black was uniformly dispersed in the particles, and the presence of voids (voids) was not recognized.

The spherical colored resin fine particles were mixed with hydrophobic silica "AEROSIL R972" (average primary particle diameter 16n).
m. 0.3% by weight of Nippon Aerosil Co., Ltd.) was externally added using a Henschel mixer, and the charge amount of the obtained toner was measured and found to be −29 μC / g.

Further, using this toner, the particle size is 80 μm.
To 100 parts by weight of the ferrite carrier of m, 4 parts by weight of this toner was added and mixed to prepare a two-component dry developer for two-component electrophotography, and a commercially available electrophotographic copying machine (DC-111 manufactured by Mita Kogyo Co., Ltd., etc. ), After developing the electrostatic latent image,
A clear image was obtained that was sufficiently practical.

(Comparative Examples 1 to 4) A stirring blade of a 2 liter cylindrical reactor similar to that used in Example 1 was replaced by a Maxblend blade (Comparative Example 1), a full zone blade (Comparative Example 2), and a hoodler blade (Comparative Example 3). ), In place of the turbine blade (Comparative Example 4), the same operation as in Example 1 was performed except that the rotation speeds of the stirring blades were changed to 280, 300, 500 and 700 rpm, respectively, in order to obtain an average particle diameter of approximately 8 μm. A true spherical colored fine particle powder was obtained. As shown in Table 1, Dp / D in all four cases
The particles were broad particles having a particle size distribution of n of 1.3 to 1.7. Further, the particle ratio of 4 μm or less is 3.0 to 7.1.
%, And the particle ratio of 16 μm or more is 0.9 to 3.
It was as high as 5%.

[0081]

[Table 1]

Example 2 The average particle diameters of the toner particle production experiment conducted in Example 1 repeated 5 times were 7.9, 8.0, 7.9, 8.1 and 7.8 μm, respectively. Met.

(Comparative Examples 5-8) Table 2 shows the average particle diameters when Comparative Examples 5-8 were each repeated 5 times under the same apparatus and experimental conditions as in Comparative Examples 1-4. ,
The fluctuation between lots was larger than that in Example 2.

[0084]

[Table 2]

[0085]

EFFECT OF THE INVENTION A method for producing electrophotographic toner particles by adding and mixing an aqueous medium (B) to an organic solvent solution (A) of a mixture containing a binder resin and a colorant as essential components, and subjecting the mixture to phase inversion emulsification. In the use of a stirring device having a multi-stage stirring blade having a specific structure in a stirring tank having a cylindrical shape, the particle size distribution of toner particles can be controlled by controlling the addition method of an aqueous medium as necessary. Was so sharp that classification was unnecessary, and lot reproducibility of the average particle size was good. In addition, this has significantly improved the toner productivity and realized a significant reduction in manufacturing cost.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an example of a stirrer used in the present invention.

[Explanation of symbols]

 1 central axis 2 wide paddle 3 paddle 4 scraper 5 T-shaped plate-shaped baffle plate

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroko Sakurai 6-3-17-203 Konakadai, Inage-ku, Chiba-shi, Chiba

Claims (4)

[Claims] 1. A stirring device having a rotating shaft in which a main stirring blade and an auxiliary stirring blade are mounted in a stirring tank, wherein the main stirring blade has its end and an inner wall of the stirring tank so as to generate an ascending liquid flow during stirring. The side wall is separated from the side surface and is located at the lowermost stage of the central axis. On the other hand, the auxiliary stirring blade has a scraper inclined vertically or in a direction of scraping with its rotation. And a paddle that is connected to the scraper and is inclined vertically or in a direction that pushes down with rotation, and the upper end of the lower stirring blade in the vertically adjacent stirring blades is the upper stirring blade. Using a stirring device characterized in that it is installed so as to cause a phase shift in the direction opposite to the rotation direction of the rotation shaft with respect to the lower end of the coloring agent, the coloring agent and the coloring agent itself can be dispersed in water. Binding made of water-insoluble resin An organic solvent solution of a mixture containing a resin as an essential component is added and mixed with an aqueous medium for phase inversion emulsification, or a colorant, and an organic solvent solution containing a binder resin composed of a water-insoluble resin as an essential component. In addition, an aqueous medium containing an emulsifier and / or a dispersion stabilizer is added and mixed for phase inversion emulsification to form colored resin fine particles, and then the organic solvent is removed to obtain spherical colored resin fine particles dispersed in the aqueous medium. A method for producing an electrophotographic toner by taking out as a dry powder. 2. An aqueous medium is added to and mixed with an organic solvent solution of a self-water-dispersible non-water-soluble resin that contains a colorant and is dispersible in water by itself, and then the phase inversion emulsification is carried out. The method for producing an electrophotographic toner according to claim 1, wherein the organic solvent therein is removed and the spherical colored resin fine particles are taken out as a dry powder. 3. 50% by weight of the amount of aqueous medium required for phase inversion emulsification
The above is added at a time while stirring to the stirring tank charged with the organic solvent solution, and then the remaining aqueous medium is added at a constant rate over 0.5 hours or more to perform phase inversion emulsification. Manufacturing method of electrophotographic toner. 4. The method for producing an electrophotographic toner according to claim 1, 2 or 3, wherein a resin that can be self-dispersible in water by neutralization is used as the binding resin.