JPH04337332A - Production of resin particle - Google Patents

Abstract

PURPOSE:To obtain the subject resin particles (group of particles) having 0.1-100mum average particle size and a sharp distribution of particle size. CONSTITUTION:A method for producing a resin particle, composed of minute dispersion of a resin having one or more kinds of ionic groups such as sulfonic group, carboxylic group, phosphoric group, ammonium group and/or their salt groups into an aqueous medium, elimination of the ionic group from the above minutely dispersed particles and combination of the minutely dispersed particles into one body.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is widely used as a matting agent, anti-blocking material, carrier for chromatography, carrier for pharmaceuticals, powder coating, gap adjustment material, toner for electrophotography, cosmetics, etc. This invention relates to a method for producing resin particles that has been widely used.

0002

BACKGROUND OF THE INVENTION Conventionally, a "polymerization granulation method" can be exemplified as a method for obtaining resin particles used for such purposes. Polymerization granulation methods can be broadly classified into emulsion polymerization, suspension polymerization, seed polymerization, and dispersion polymerization.

[0003] In the emulsion polymerization method, resin particles are obtained by polymerizing in water in micelles of polymerizable monomers stabilized with a surfactant. In the emulsion polymerization method, particles having a sharp particle size distribution can be obtained. However, the particle size is determined by the size of micelles that can stably exist, so the particle size is approximately 0.
．． Limited to the range of 01 to 0.5 μm, approximately 1 μm
It is impossible to obtain particles with a larger particle size. Furthermore, since the surfactant essential for stabilizing micelles remains on the surface of the prepared particles, the range of use of the obtained resin particles is limited.

The suspension polymerization method is a method in which particles are obtained by polymerizing polymerizable monomers in a suspension system obtained by mechanically stirring water and polymerizable monomers. In the suspension polymerization method, the particle size depends on mechanical stirring, so the shear
It is difficult to obtain polymer particles with a narrow particle size distribution. The particle size range of particles obtained by suspension polymerization method is approximately 10 μm.
That's all.

[0005] In the seed polymerization method, particles obtained by other methods are used as seed particles, the seed particles are swollen with a solvent and a polymerizable monomer, and in the swollen seed particles, This is a method of growing seed particles to a large size through polymerization. In the seed polymerization method, in principle, particles with a sharp particle size distribution can be obtained by selecting appropriate seed particles, and the particle size of the particles is The swelling ratio of the -de particles and the polymerizable monomer can be controlled. In the seed polymerization method, particles obtained by emulsion polymerization, ie, vinyl polymer particles, are used as seeds. It is difficult to swell vinyl polymer particles with polymerizable monomers. The swelling rate is determined by the interaction between the polymer constituting the seed particles and the monomer used for swelling, and
It is determined by the balance with the interfacial tension of the swollen particles, and in reality, the limit is about 2 to 10 times at most. That is, the swelling ratio cannot be made extremely large, and there is naturally a limit to the particle size range that can be grown at one time. Increasing the particle size by 10 times increases the volume by 100
This corresponds to increasing the amount by 0 times, so in order to achieve this by seed polymerization, it is necessary to repeat the seed polymerization. The two-step swelling seed polymerization method is a method devised to increase the swelling ratio of seed particles. In the two-step swelling seed polymerization method, seed particles are first swollen with an oligomer or a poorly water-soluble low molecular weight substance (swelling agent), and then swelled with a polymerizable monomer. By this method, the swelling rate of the seed particles can be increased several thousand times. However, since swelling agents remain in the particles obtained by the two-stage swelling seed polymerization method, a step for removing them is essential. The seed polymerization method and the two-step swelling seed polymerization method are excellent methods in the sense of producing micron-order resin particles with a sharp particle size distribution, but the above-mentioned problems arise in the seed polymerization method. This makes it difficult to commercialize the depolymerization method.

In the dispersion polymerization method, a polymerizable monomer, an initiator,
This method involves dissolving a stabilizer in an organic solvent and initiating polymerization, thereby growing polymer particles insoluble in the organic solvent using the oligomer aggregates generated in the initial stage as particle nuclei. Although the dispersion polymerization method is an excellent method for producing micron-order resin particles with a sharp particle size distribution, it is difficult to mass produce because it uses an organic solvent as a medium, and the industrial production of resin particles is difficult. It cannot be established as a production method.

[0007] The above-mentioned "polymerization granulation method", that is,
Resin particles produced by emulsion polymerization, suspension polymerization, seed polymerization, and dispersion polymerization are limited to "vinyl polymer" particles, as is obvious from the manufacturing method. By such a method, resin particles of condensation polymers such as polyester, polyamide, etc. cannot be obtained. As methods for producing resin particles that are not limited to the type of resin, methods such as a mist drying method, a salting out method, a solvent removal method, and a dispersion molding method have been proposed.

The mist drying method is a method for obtaining particles by drying a resin emulsion or solution. The particle size of the obtained particles can be controlled to some extent by controlling the concentration of the emulsion or solution and the size of the mist droplets formed during mist drying. However, it is difficult to make the size of the mist droplets perfectly uniform, and since the mist droplets coalesce, the resulting particles have a broad particle size distribution.

[0009] The salting out method is a method in which a resin dissolved in a solvent is extruded into a system in which the resin is insoluble to precipitate it and form particles. According to this method, it is possible to control the average particle size to some extent by controlling the concentration of the solution. However, since the size of individual particles depends on the mechanical conditions after discharge, the particle size distribution will still be somewhat broad.
It has to be something terrible.

The solvent removal method is a method in which resin particles are obtained by mechanically suspending a solution of a resin dissolved in an organic solvent in water and gradually volatilizing the organic solvent. In this method, like the suspension polymerization method, the particle size depends on mechanical stirring, so it is difficult to obtain fine resin particles with a uniform particle size distribution.

[0011] The dispersion molding method is a method in which, after pulverizing a resin, the pulverized particles are dispersed in a nonsolvent of the resin, and the particles are sphericalized by applying a temperature higher than the softening temperature of the resin. However, it is difficult to disperse fine powder in water, and a dispersant, suspension stabilizer, etc. are essential. Since these remain on the surface of the produced particles, the range of use of the obtained resin particles is limited. Since the pulverized resin has an amorphous shape, it is difficult to make the particle size uniform through classification, and furthermore, the particle size distribution becomes broad due to secondary aggregation of resin particles that occurs in a non-solvent. . In order to suppress secondary agglomeration of resin particles, it is necessary to lower the concentration of resin particles in the dispersion medium, and in addition to the difficulty of dispersing resin particles itself mentioned above, it is difficult to realize this method industrially. It makes it difficult.

0012

[Problems to be Solved by the Invention] As mentioned above, the conventional method for producing resin particles is highly dependent on the type of resin, and moreover, it is difficult to produce a resin that has a sharp particle size distribution at a given particle size. It has been difficult to produce the particles industrially.

[0013]

[Means for Solving the Problems] In view of this situation, the present inventors have developed a method that has a sharp particle size distribution and has a particle diameter of 0.1 μm.
As a result of intensive research to find an industrial method for producing resin particles (resin particle group) having arbitrary particle diameters in the range from 100 μm to 100 μm and independent of the type of resin, the following invention was achieved. That is, the present invention provides at least one group selected from a sulfonic acid group, a carboxyl group, a phosphoric acid group, an ammonium group, and/or a salt group thereof.
An ionic group-containing resin containing various types of ionic groups in the range of 5 to 1000 milliequivalents/kg is microdispersed in an aqueous medium, and then the ionic groups contained in the microdispersed particles are cut off. This method of producing resin particles is characterized by destroying the stability of dispersed particles and causing the resin particles to grow into coalesced particles.

Since the purpose of the present invention is to provide a method for producing resin particles that does not depend on the type of resin, the type of resin is not limited in any way, and includes vinyl resins such as styrene and acrylic resins, It can be applied to all kinds of resins that can be water-dispersed by introducing ionic groups, such as condensation resins such as polyester and polyamide resins, or epoxy resins.

However, the significance of the present invention can be realized by applying it to areas where industrial resin particle manufacturing methods have not yet been established, that is, to condensation resins such as polyester resins and polyamide resins. Particularly preferred are polyester resins, and both saturated polyester resins and unsaturated polyester resins can be used as the polyester resin. The polyester resin in the present invention is
It mainly consists of a dicarboxylic acid resin and a glycol component. Examples of the dicarboxylic acid component include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, orthophthalic acid, and 1,5-naphthalic acid, p-oxybenzoic acid,
Aromatic oxycarboxylic acids such as p-(hydroxyethoxy)benzoic acid, succinic acid, adipic acid, azelaic acid,
Aliphatic dicarboxylic acids such as sebacic acid and dodecanedicarboxylic acid, unsaturated aliphatic acids such as fumaric acid, maleic acid, itaconic acid, hexahydrophthalic acid, and tetrahydrophthalic acid, and alicyclic dicarboxylic acids are used. be able to. As the acid component, a small amount of tri- and tetracarboxylic acids such as trimellitic acid, trimesic acid, and pyromellitic acid may be included if necessary. As a glycol component,
For example, ethylene glycol, propylene glycol,
1,3-propanediol, 1,4-butanediol,
1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, diethylene glycol, dipropylene glycol, 2,2,4-trimethyl-1,
3-pentanediol, 1,4-cyclohexanedimethanol, spiroglycol, 1,4-phenylene glycol, ethylene oxide adduct of 1,4-phenylene glycol, dimethylolheptane, tricyclodecane Diols, diols such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol, ethylene oxide adducts and propylene oxide adducts of bisphenol A, hydrogenated bisphenol A
Ethylene oxide adducts, propylene oxide adducts, and the like can be used. In addition to these, small amounts of triols and tetraols such as trimethylol ethane, trimethylolpropane, glycerin, and pentaelthritol may be included, if necessary. The polyester polyol may also include lactone-based polyester polyols obtained by ring-opening polymerization of lactones such as ε-caprolactone. Among polyester resins, particularly preferably used resins are those in which an aromatic polycarboxylic acid is used as the acid component and an aliphatic and/or alicyclic polyhydric alcohol is used as the alcohol component.

The ionic group contained in the resin has the function of stably dispersing the resin in an aqueous medium. What is stable dispersion?
It means a state in which the resin itself is dispersed in an aqueous medium due to the action of an electric double layer formed by dissociation of ionic groups contained in the resin itself. The ionic groups contained in the resin include anionic groups such as carboxyl groups, sulfonic acid groups, sulfuric acid ester groups, phosphoric acid groups, or salts thereof (hydrogen salts, metal salts, ammonium salts), or It is a cationic group such as a primary to tertiary amine group, and preferably a carboxyl group, an ammonium carboxylate base, a sulfonic acid group, an alkali metal sulfonate base, etc. can be used. These ionic groups are preferably contained in a form in which an ionic group-containing monomer is copolymerized with the resin, or in a form in which it is grafted onto a side chain of the resin.

[0017] In the polyester resin, it is preferable that the ionic group is contained in the form of copolymerization with the resin or in the form of being introduced at the end of the polymer. As the ionic group-containing compound copolymerizable with the polyester resin, examples of the sulfonic acid metal base-containing compound include sulfoterephthalic acid, 5
-Metal salts such as sulfoisophthalic acid, 4-sulfophthalic acid, 4-sulfonaphthalene-2,7dicarboxylic acid, and 5[4-sulfophenoxy]isophthalic acid, and as amino group-containing compounds, 2-dimethylaminomethyl, 2- Methyl 1
, 3-propanediol, etc. Examples of metal salts include salts of Li, Na, K, Mg, Ca, Cu, Fe, etc., and particularly preferred is Na salt. Furthermore, when introducing an ionic group to the end of the polymer, for example, sulfobenzoic acid and its metal salts can be used.

These ionic groups are essential for stably dispersing the resin in an aqueous medium. The content of ionic groups can be arbitrarily set within a range that allows the target resin to be dispersed in water, but is generally 5 to 100% of the resin.
0 meq/kg, preferably 10-500 meq/kg
kg, more preferably 20 to 200 milliequivalents/kg,
is within the range of If the ionic group content is less than this lower limit, it may be difficult to microdisperse the resin in an aqueous medium. Moreover, if the upper limit is exceeded, the resin may become water-soluble.

The method of microdispersing the resin containing ionic groups in an aqueous medium is not particularly limited, but for example, the resin is once dissolved in an amphoteric solvent such as alcohol, cellosolve, or ketone, and then the resin is dissolved therein. how to add water to,
Examples include a method of directly adding hot water to a hot molten resin, and a method of mixing water and a bipolar solvent in advance and adding the mixture to the resin. The resin into which ionic groups have been introduced in the present invention has a self-emulsifying effect and is therefore rapidly microdispersed. The particle size of the microdispersed particles takes a value between about 0.01 μm and 1.0 μm, but in the present invention, it is approximately 0.05 to 0.0 μm.
It is preferable to adjust the microdispersion step and the ionic group content of the resin so that the particle size is about 5 μm. Furthermore, a microdispersion obtained by emulsion polymerization of a vinyl monomer may be used to create the presence of a reactive monomer containing an ionic group. The micro-dispersed particles of ionic group-containing resin produced in this way have an electric double layer formed on their surface due to the dissociation of the ionic groups possessed by the resin itself, and have extremely stable dispersion ability. be.

[0020] Even if such microdispersed particles are dried and taken out, they aggregate due to their small particle size, and it is impossible to take out individual particles as independent powders, so their industrial applicability is extremely low. It will be limited. Attempts have been made to cause the microdispersed particles to moderately agglomerate into resin particles with a certain size by applying a coagulant or the like to an aqueous dispersion of such a resin. Since the resin particles cannot be formed uniformly, the particle size distribution of the resulting resin particles becomes broad. In the present invention, the electric double layer is not destroyed by an external environmental element such as a coagulant and the micro-dispersed particles are aggregated, but the ionic groups themselves present on the surface of the micro-dispersed particles are cut off from the resin. The feature is that the dispersion stability of the micro-dispersed particles is destroyed, and a plurality of micro-dispersed particles are combined to cause particle growth.

[0021] There is no particular restriction on the method of cutting off the ionic group from the resin, but preferably by heating in an alkaline or acidic environment.
Alternatively, a method in which a part of the polymer containing an ionic group is hydrolyzed is preferred. The method of controlling the pH of the system is not particularly limited, but in order to avoid sudden pH changes, electrolytes with a certain degree of buffering effect, such as acetic acid and dimethylamine, trimethylamine, dimethylaminoethanol, etc. are used.
It is desirable to control the pH by using ammonium cations such as chloride, or alkali metal ions. Note that a hydrolysis catalyst may also be used at this time. Examples of the hydrolysis catalyst include compounds containing a carboxyl group, a sulfonic acid group, or a salt group thereof. Furthermore, when a carbonate group, a phosphoric acid group, or the like is used as an ionic group, it is possible to cut off the ionic group by heating or light irradiation.

Microdispersed particles with ionic groups cut off have unstable dispersibility because the density of ionic groups on their surfaces decreases. Therefore, they aggregate and coalesce with other particles, but as the specific surface area of the resin particles decreases due to coalescence, the ionic group density on the particle surface increases (returns to its original state) and regains dispersion stability. The most characteristic effect of the present invention is stabilization of redispersion due to the coalescence of a plurality of particles. That is, in a system where the dispersion stability has been disrupted by external environmental factors such as the introduction of a flocculant, the dispersion stability once disrupted does not return to its original state and aggregation progresses over time. Therefore, due to mechanical action such as stirring, agglomeration of particles progresses until aggregation and separation of agglomerates reach equilibrium, and the particle size distribution of the resulting particles depends on the mechanical environment. However, in a system in which dispersion stability, which has once collapsed, is restabilized by particle coalescence, particle aggregation does not proceed indefinitely, but proceeds depending on the degree of release of ionic groups. Therefore, the particle size of the resin particles obtained can be easily controlled by changing the amount of ionic groups released and the speed thereof, and the particle size distribution thereof can be extremely sharp.

The amount of ionic groups to be cut off depends on the particle size of the initial microdispersed particles and the particle size of the desired resin particles, so it is difficult to limit it unconditionally. If the diameter is assumed to be 0.1 μm and the target particle size is approximately 1 to 10 μm, this corresponds to cutting off approximately 10 to 50% of the initial ionic group content. If defects occur due to residual ionic groups in the desired resin particles, the removal may be performed not within this range, but until the content of ionic groups can be considered to be substantially nil.

[0024] In order to achieve redispersion stability through coalescence, the specific surface area of the resin particles must be rapidly reduced through coalescence, that is, the resin particles must become spherical. Therefore, the environment in which the ionic group is cut off is preferably such that the resin is plasticized to some extent. Plasticization of the resin is achieved, for example, by introducing a solvent or the like, or simply by raising the environmental temperature above the softening point of the resin.

In addition, other dispersion stabilizers may be added to the system in order to prevent unnecessary agglomeration of the particles until the particles lose their stability due to the release of ionic groups and are re-stabilized by coalescence and spheroidization. There is no problem in introducing it. Examples of dispersion stabilizers having such an effect include formalin condensates of naphthalene sulfonates, polystyrene sulfonates, polyacrylic acids or salts thereof, polyvinyl alcohols,
Other commercially known cationic, anionic, or nonionic dispersants having a protective colloid effect can also be used. Further, inorganic fine particles such as silica, alumina, titanium oxide, etc. can also be used as a dispersion stabilizer.

The obtained resin particles are taken out as a dry powder by a conventional method such as filtration, freeze drying, spray drying, fluidized drying or the like. By coexisting other dispersions, such as pigments, inorganic particles such as carbon black, silica, and talc, or polymer particles, in the aqueous medium used for the coalescence growth of resin particles, these particles can be grown. It can be incorporated into particles as they coalesce and grow. These can be added as appropriate for the purpose of imparting color or hiding properties to the resin particles, and further imparting other functionality, within a range that does not impair the stability of the dispersion. Furthermore, the resin particles obtained by the present invention have excellent dispersion stability in an aqueous medium, and therefore can be easily colored with dyes. The resin particles in the present invention can be easily colored at a high concentration with disperse dyes, Vat dyes, acid dyes, basic dyes, and the like.

[0027] The present invention will be explained in more detail with reference to Examples below, but the present invention is not limited to these in any way.

[Example 1] Dimethyl terephthalate was placed in an autoclave equipped with a thermometer and a stirrer.
151 parts by weight,
dimethyl isophthalate
47 parts by weight, 5
-Sodium sulfodimethyl isophthalate
9 parts by weight, tricyclodecane dimethylo-
40 parts by weight,
ethylene glycol
140 parts by weight,
Tetrabutoxy titanate
Prepare 0.1 part by weight, 180
The transesterification reaction was carried out by heating at ~230°C for 120 minutes. Then, the temperature of the reaction system was raised to 250°C, and the system pressure was reduced to 1
As a result of continuing the reaction for 60 minutes at a pressure of ~10 mmHg, a copolyester resin (A1) was obtained. The obtained copolymerized polyester resin (A1) has a number average molecular weight of 3800, a glass transition temperature of 63.4°C, and a composition determined by NMR analysis to contain terephthalic acid as an acid component.
72.6mol% isophthalic acid
24.4mo
l %5-Sodium sulfoisophthalic acid
3.0mol% Ethylene glycol as alcohol component
It was 79.3 mol% tricyclodecane dimethylol and 20.7 mol%. Also S
The sodium sulfonate group content was determined to be 102 milliequivalents/kg.

After dissolving 100 parts by weight of copolymerized polyester resin (A1) and 30 parts by weight of butyl cellosolve at 110°C, 200 parts of water at 80°C was added to obtain a particle size of about 0.1μ.
An aqueous microdispersion of a copolymerized polyester resin of m was obtained. Furthermore, the obtained aqueous microdispersion was placed in a distillation flask and distilled until the distillate temperature reached 100°C, and after cooling, water was added to make the solid content concentration 34%. 220 parts by weight of copolyester aqueous dispersion, 1.5 parts by weight of acetic acid, and 1.0 parts by weight of sodium hydroxide were added to a four-necked 1-liter separable flask equipped with a thermometer, condenser, and stirring blade. . The pH of the system was 5.5. Then, the temperature was raised to 90°C and stirring was continued for 180 minutes. As a result, the particle size present in the copolymerized polyester aqueous dispersion was 0.1μ.
The micro-dispersed particles of m grow as coalesced particles and have an average particle size of 6.3.
Substantially spherical polyester resin particles were obtained with an occupation rate of 97 wt% of particles having a particle size in the range of 0.5D to 2D, where D is the diameter. The sodium sulfonate group content of the obtained polyester particles was 64 meq/kg, and about 27% of the initial ionic groups were cleaved.

[0029]

[Example 2] Dimethyl terephthalate was placed in an autoclave equipped with a thermometer and a stirrer.
570.4 parts by weight,
dimethyl isophthalate
564.5 parts by weight, sodium sulfobenzoic acid methyl ester 35.7 parts by weight,
ethylene glycol
491.0 parts by weight,
Neopentyl glycol
549.1 parts by weight, tetrabutoxy titanate
Prepare 0.5 parts by weight and heat at 180 to 230℃ for 12 hours.
The transesterification reaction was carried out by heating for 0 minutes. Then, the temperature of the reaction system was raised to 250°C, and the reaction was continued for 60 minutes at a system pressure of 1 to 10 mmHg, thereby obtaining a copolymerized polyester resin (A2). The obtained copolymerized polyester resin (
A2) has a number average molecular weight of 4500 and a glass transition temperature of 57.
．． At 4℃, the composition was determined by NMR analysis to be terephthalic acid as the acid component.
49.1mol% isophthalic acid
48.5mo
l% sodium sulfobenzoic acid
2.6mol% Ethylene glycol as alcohol component
58.4mol% neopentyl glycol
It was 41.6 mol%. Also, from the determination of S, the sodium sulfonate group content was 86
It was milliequivalent/kg.

After dissolving 100 parts by weight of copolymerized polyester resin (A2) and 30 parts by weight of butyl cellosolve at 110°C, 200 parts of water at 80°C was added to obtain a particle size of about 0.1μ.
An aqueous microdispersion of a copolymerized polyester resin of m was obtained. Furthermore, the obtained aqueous microdispersion was placed in a distillation flask and distilled until the distillate temperature reached 100°C, and after cooling, water was added to make the solid content concentration 34%. Copolymerized polyester aqueous microdispersion 2 was placed in a four-necked 1-liter separable flask equipped with a thermometer, condenser, and stirring blade.
20 parts by weight and 2.0 parts by weight of acetic acid were added, and then dimethylaminoethanol was added to adjust the pH of the system to 9.5. Then, the temperature was raised to 70°C and stirring was continued for 120 minutes. As a result, the microdispersed particles with a particle size of 0.1 μm that were present in the copolymerized polyester aqueous dispersion grew into coalesced particles, with an average particle size of 4.5 μm and a diameter of 0.5D~2
Polyester resin particles were obtained in which the occupancy of particles having a particle size in the range D was 94 wt %. The sodium sulfonate group content of the obtained polyester particles was 52 milliequivalents/kg, and about 40% of the initial ionic groups were cleaved.

[0031]

[Example 3] A methacrylic ester containing sodium benzenesulfonate (H2 C=C(C
H3 ) COO(CH2 CH2 O)4 C6 H5
1 part by weight of SO3 Na) and 1500 parts by weight of deionized water were charged and mixed at room temperature. Then, methyl methacrylate (H2C=C(CH3)COOCH3)49
parts by weight and 50 parts by weight of styrene were added, and the temperature was raised while flowing nitrogen gas into the flask. When it reached 70°C, 0.5 parts by weight of potassium peroxodisulfate was added, and the temperature of the system was maintained at 70°C. Stirring was continued for 240 minutes. As a result, the monomers in the system underwent emulsion polymerization to obtain a microdispersion (C) of a methacrylic acid/styrene copolymer containing a sodium sulfonate group. The particle size of microdispersed particles is approximately 0.07
As a result of salting out a part of the microdispersion and quantifying S, the content of sodium sulfonate groups in the copolymer was 97 milliequivalents/kg.

100 parts by weight of a microdispersion (C) of a methacrylic acid/styrene copolymer containing a sodium sulfonate group was placed in a four-necked 1-liter separable flask equipped with a thermometer, a condenser, and a stirring blade. Trimethylamine was then added to bring the pH of the system to 11. Then, the temperature was raised to 90°C and stirring was continued for 120 minutes. the result,
The microdispersed particles with a particle diameter of 0.07 μm that were present in the microdispersion grew into coalesced particles, and the average particle diameter was 12.5 μm, and when the diameter was D, the particles with a particle size in the range of 0.5D to 2D occupied. Resin particles having a ratio of 89 wt% were obtained. The sodium sulfonate group content of the obtained particles was 58 meq/k
g, and approximately 40% of the initial ionic groups were cleaved.

[0033]

[Effects of the Invention] As described above, the present invention enables industrial production of resin particles having any average particle size and sharp particle size distribution, and is not dependent on the type of resin in principle. This method is extremely useful as a method for producing resin particles.

Claims (1)

[Claims] Claim 1: At least one type of ionic group selected from a sulfonic acid group, a carboxyl group, a phosphoric acid group, an ammonium group, and/or a salt group thereof, in an amount of 5 to 1000
The ionic group-containing resin containing milliequivalents/kg is microdispersed in an aqueous medium, and then the stability of the microdispersed particles is broken by cutting off the ionic groups contained in the microdispersed particles. A method for producing resin particles, characterized by growing particles in a coalesced particle manner.