JPH08143627A - Production of singly dispersible polystyrene particle - Google Patents

Abstract

PURPOSE: To obtain the subject particles useful for delustering agents, chromatrographic carriers, medicine carriers, powder coatings, electrophotographic toners, cosmetics, etc., by polymerizing a styrenic monomer in the presence of a specific polymer as a stabilizer. CONSTITUTION: (B) Styrene or its mixture with a copolymerizable monomer such as a monomer of formula II (R<2> is H, methyl; R<3> is H, an <=18C alkyl) is polymerized in the presence of (S) a polymer containing 0.1-20 pts.wt. of (A) a monomer of formula I (R<1> is an <=18C alkyl, phenyl) and having a weight- average mol.wt. of >=10000 in an alcoholic solvent comprising a <=4C aliphatic alcohol, an ether alcohol, etc., to obtain the objective particles having an average particle diameter of 1-20μm. The polymerization is preferably performed by controlling the pH of the alcoholic solvent containing the preliminarily dissolved polymer S to 8-13, heating the Ph controlled solution at a room temperature to 80 deg.C for 15min to 1hr to convert the thiol ester group of formula I into the mercapto group, and subsequently polymerizing the monomer (mixture) B.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to resin particles which are widely used as matting agents, chromatographic carriers, medicinal carriers, powder coatings, electrophotographic toners, cosmetics, etc. The present invention relates to a method for producing micron-sized resin particles having various particle size distributions.

[0002]

2. Description of the Related Art As a conventional method for producing micron-sized monodisperse polymer particles, a suspension polymerization method,
The seed polymerization method and the dispersion polymerization method can be used.

The suspension polymerization method is a method in which a monomer is mechanically stirred in water in the presence of a dispersion stabilizer to form droplets, and particles are obtained by using an appropriate oil-soluble polymerization initiator. In the suspension polymerization method, it is difficult to obtain particles having a sharp particle size distribution because the particle size depends on mechanical stirring.

The seed polymerization method is a method in which polymer particles previously synthesized by some method are used as seed particles and the seed particles are swollen with a solvent and a polymerizable monomer to increase the particle size. The limit is about 10 times the volume, and seed polymerization must be repeated several times to obtain particles having a large particle size. Also, J.
A two-step swelling seed polymerization method developed by Ugelstd et al. (J. Polymer Science, Polym. Symposium 72,225 (198
5)) enhances the monomer absorption capacity of the seed particles,
1 by volume by using swelling aids such as oligomers
This is a method for obtaining large particles by increasing the swelling ratio up to about 000 times. This method requires removal of the swelling aid. The seed polymerization method and the two-step swelling seed polymerization method are very effective as a method for synthesizing monodisperse micron-sized particles, but it takes time and labor because two or more steps are involved, and the manufacturing cost is also industrial. It is not preferable as a method.

In the dispersion polymerization method, particles are obtained by polymerizing in an organic solvent in the presence of a dispersion stabilizer in such a system that the polymerizable monomer is dissolved in the solvent but the obtained polymer is insoluble in the solvent and precipitates. Is the way. The dispersion polymerization method is advantageous in terms of labor and cost since micron-sized monodisperse particles can be obtained in one step. Generally, Y. Almog et al. (British Polym J. 14, 131 (1982)) and J. W. Van
derhoff et al. (J. Polym Science: Part A: 24, 2995 (19
86)), a method of synthesizing polystyrene particles by a dispersion polymerization method is known, but in these methods, the particle size and the monodispersity are remarkably increased depending on the conditions such as the concentration of the polymerizable monomer and the concentration of the dispersant. It tends to change, and sub-micron-sized particles are likely to be by-produced or aggregated. The particle size distribution of the copolymer particles of styrene and various acrylate monomers also tends to widen. Therefore, from an industrial point of view, there is a problem in large-scale and stable production. Furthermore, since a large amount of at least 10 to 20% of the polymer dispersant with respect to the particles is required, the obtained particles and the dispersant are not sufficiently separated, and the polymer dispersant is excessively adsorbed on the particle surface. , Particles tend to adhere to each other, resulting in poor redispersibility.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for producing polystyrene particles which can stably obtain monodisperse particles by a dispersion polymerization method against changes in polymerization conditions. Further, by using a small amount of the dispersion stabilizer, the contamination of the surface of the particle with the dispersion stabilizer is reduced to obtain particles having good redispersibility. Further, it is also necessary to obtain similar particles having good monodispersity in a copolymerization system of styrene and a monomer copolymerizable with styrene.

[0007]

According to the present invention, a monomer B shown above is polymerized in an alcoholic medium in the presence of a polymer S as a dispersion stabilizer having the monomer A shown in the chemical formula 1. By doing so, the average particle size is 1 μm
The method for producing monodisperse polystyrene-based particles is characterized by producing monodisperse polystyrene-based particles having a particle size of 20 μm or less.

The monomer A represented by the chemical formula 1 may be an ortho isomer, a meta isomer or a para isomer, and in the chemical formula 1, R ¹ has 18 carbon atoms
The following alkyl group or phenyl group is represented. Examples thereof include thioacetic acid, thiopropionic acid, thiobutyric acid, thiovaleric acid, thiocaproic acid, and thiobenzoic acid.

As the monomer B forming particles,
Styrene may be used alone or a mixture of styrene and a monomer copolymerizable with styrene may be used. The monomer copolymerizable with styrene is preferably the monomer shown in Chemical Formula 2 or monomers having two or more double bonds in the molecule. In the chemical formula ² , R ² represents a hydrogen atom or a methyl group, and R ³ represents a hydrogen atom or an alkyl group having 18 or less carbon atoms.

The compound represented by Chemical formula 2 is acrylic acid, methacrylic acid and esters thereof, such as methyl acrylate, ethyl acrylate, n-butyl acrylate, tert-butyl acrylate, 2-ethylhexyl acrylate, Methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, tert-methacrylate
Butyl, 2-ethylhexyl methacrylate and the like can be mentioned. Examples of the monomer having two or more double bonds in the molecule include divinylbenzene, divinylnaphthalene, and aromatic divinyl compounds which are derivatives thereof, ethylene glycol dimethacrylate, diethylene glycol diacrylate, trimethylolpropane triacrylate, trimethylol. Propane trimethacrylate, allyl methacrylate, vinyl methacrylate, 1,3
-Diethylenic acrylic acid such as butanediol dimethacrylate and methacrylic acid ester.

The mixture of styrene with a monomer copolymerizable with styrene may be a mixture of styrene with one monomer selected from the monomers capable of copolymerization,
It may be a mixture of two or more kinds of monomers selected from copolymerizable monomers and styrene. Further, it is preferable to use these monomers copolymerizable with styrene in an amount of 1 to 40 parts by weight in 100 parts by weight of the mixture.

As the alcoholic medium, methanol,
Ethanol, n-propanol, isopropanol, n
Preferred examples include aliphatic alcohols having 4 or less carbon atoms such as -butyl alcohol and tert-butyl alcohol, and ether alcohols such as methyl cellosolve and ethyl cellosolve. These are used alone or as a mixture of two or more kinds. When alcohols other than these are used alone, the monodispersibility of the particles obtained may decrease, but aliphatic alcohols having 5 to 8 carbon atoms, such as n-pentanol, n
-Hexanol, n-octanol and the like can be advantageously used by mixing with aliphatic alcohols having 4 or less carbon atoms. Further, a medium miscible with aliphatic alcohols having 4 or less carbon atoms, for example, aromatic hydrocarbons such as benzene, toluene, xylene, ethers such as ethyl ether and tetrahydrofuran, ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone. A mixed medium containing 20 parts by weight or less in 100 parts by weight of the mixed medium is preferably used. By changing the solubility parameter of the medium, it is possible to control the particle size and particle size distribution of the particles obtained by synthesis.

The polymer S is the monomer A shown in the chemical formula 1 above.
Is a copolymer containing 0.1 to 20 parts by weight of
And at least one of the monomers C selected from the monomer group represented by the above Chemical formula 3, Chemical formula 4, Chemical formula 5, Chemical formula 6, Chemical formula 7, and Chemical formula 8
A copolymer containing 50 to 99.9 parts by weight of the seed is preferably used. Here, in Chemical formula 3, R ⁴ represents a hydrogen atom or a methyl group, R ⁵ and R ⁶ represent a methyl group or an ethyl group,
n represents an integer of 1 to 3. In Chemical Formula 4, R ⁷ represents a hydrogen atom or a methyl group, and R ⁸ and R ⁹ represent a hydrogen atom or an alkyl group having 4 or less carbon atoms. In Chemical formula 5, R ¹⁰ , R ¹¹ , and R ¹² represent a hydrogen atom or a methyl group, and n represents an integer of 0 to 10. In Chemical formula 7, R ¹³ represents a hydrogen atom or a methyl group.

As a concrete example of the chemical formula 3, acrylic acid 2-
(N, N-dimethylamino) ethyl, acrylic acid 2-
(N, N-diethylamino) ethyl, methacrylic acid 2-
(N, N-dimethylamino) ethyl, methacrylic acid 2-
An acrylic monomer having an amino group such as (N, N-diethylamino) ethyl may be mentioned. As specific examples of the chemical formula 4, N, N-dimethylacrylamide, N, N-
Examples thereof include acrylamide monomers such as diethyl acrylamide, N, N-dimethylaminopropyl acrylamide, ethyl acrylamide, N-isopropyl acrylamide and tert-butyl acrylamide. Specific examples of Chemical Formula 5 include acrylic monomers having a carboxyl group or a hydroxyl group such as acrylic acid, methacrylic acid, 2-hydroxyethyl acrylate, and 2-hydroxyethyl methacrylate, and as Chemical Formula 6, N- Specific examples of vinylpyrrolidone and Chemical formula 7 include monomers having a nitrogen atom or a heterocycle thereof such as vinylpyridine and vinylimidazole.

In producing the polymer S, the monomer C is used.
One type may be copolymerized with the monomer A, or two or more types of the monomer C selected from the above-mentioned monomer group may be used as the monomer A.
It may be copolymerized with. These monomers A and C are polymerized in an alcoholic medium to obtain a polymer S.

Monodisperse particles are synthesized by polymerizing the monomer B in a medium in which the polymer S is dissolved.
In the polymer S synthesized from the monomer A and the monomer C, the particle size of the polystyrene particles synthesized by using the polymer S containing 0.1 to 20 parts by weight of the monomer A and having a large content of the monomer A is It tends to become smaller.

When the molecular weight of the polymer S is too low, particles may not be formed even if dispersion polymerization is carried out in the presence of the polymer S, so that the weight average molecular weight of 10,000 or more is preferable. The polymer S may be used as it is after polymerization,
A polymer purified by precipitation using a suitable poor solvent may be used. Further, the amount of the polymer S used is suitably in the range of 0.1 to 30 parts by weight with respect to 100 parts by weight of the monomer B forming particles, and a more preferable amount of use is 0.5.
10 to 10 parts by weight, and particularly preferably 0.5 to
It is in the range of 5 parts by weight. No significant change was found in the particle size of the polystyrene-based particles synthesized in this range, and monodisperse particles having a narrow particle size distribution were obtained.

As the polymerization initiator, for example, 2,2'-azobisisobutyronitrile and 2,2'- are used.
Azobis (2-methylbutyronitrile), 2,2'-azobis (2,4-dimethylvaleronitrile), dimethyl 2,2'-azobis (2-methylpropionate),
Examples thereof include azo initiators such as 4,4′-azobis (4-cyanovaleric acid) and peroxide initiators such as benzoyl peroxide.

The concentration of the polymerization initiator is preferably 0.1 to 5 parts by weight with respect to 100 parts by weight of the monomer B. Under normal polymerization conditions, 1 to 2 parts by weight is used, and the particle size of polystyrene particles produced tends to increase as the concentration of the polymerization initiator increases.

The concentration of the monomer B at the start of polymerization is
45% by weight or less is suitable in the alcoholic medium, but if the particle size distribution is to be extremely narrowed, it is preferably 40% by weight or less.

Polymerization is carried out by dissolving the polymer S in an alcoholic medium, adding the monomer B under a nitrogen atmosphere while stirring, and adding a polymerization initiator after heating. Polymerization time is 6
It takes about 12 hours. Further, the polymerization rate can be increased and the polymerization time can be shortened by further adding a polymerization initiator during the polymerization.

At this time, the polymer S may be dissolved in an alcoholic medium, and then the monomer B may be added to carry out the polymerization as it is. However, under a nitrogen atmosphere, the pH is adjusted to 8 to 13 by using an appropriate alkali. After heating at room temperature to 80 ° C. for about 15 minutes to 1 hour, it is desirable to add the monomer B to carry out these polymerizations. This is because the thiol ester group in the polymer S is hydrolyzed and converted into a mercapto group under alkaline conditions. Since the converted mercapto group undergoes chain transfer to the monomer B, a graft polymer of the polymer S and the monomer B is formed, and the polymer S as a dispersion stabilizer is more efficiently immobilized on the particle surface. Become. Therefore, by hydrolyzing the polymer S before the polymerization of the monomer B, it is possible to stably synthesize the particles by using a small amount of the dispersion stabilizer and to obtain the particles having good monodispersity. Generally, although particles obtained by polymerization of styrene alone have good monodispersity, the particle size distribution of copolymer particles of styrene and a monomer copolymerizable with styrene is often wide, but when the polymer S is used, Due to the effects as described above, similar monodisperse particles can be obtained for the copolymer particles.

After the completion of the polymerization, the polymer slurry is recovered by operations such as sedimentation, centrifugation, decantation, etc.
After washing, filtering and drying, a powder of polystyrene particles can be obtained. The particles obtained as a powder are easily redispersed in water or an alcoholic medium.

The dry powder thus obtained can be used in various fields such as dry toners, fillers and matting agents as specific application examples, and in each case, the individual powder particles can be used. It is necessary that the particles do not agglomerate, and if adhesion and agglomeration of the powder particles occur, there is no point in synthesizing the monodisperse particles. One of the effects of the monodisperse particles obtained in the present invention is that the monodispersity of the particles obtained by synthesis is further improved as compared with the conventional method, and the obtained monodisperse particles are dried. It can be mentioned that the fluidity of the particles when taken out as particles is excellent, adhesion and coalescence of particles are not observed, and the redispersibility in liquid is also very excellent.

[0025]

EXAMPLES The present invention will be described in more detail with reference to examples.

Synthesis Example 1 (Polymer S) 40 g of ethanol, 160 g of water, 1 g of 4-vinylbenzyl thioacetate as monomer A and 1 g of N-vinylpyrrolidone as monomer B were put in a 500 ml four-necked flask.
00 g was added, and the mixture was heated to 55 ° C. with stirring under a nitrogen atmosphere to obtain 2,2′-azobis [2- (2-imidazoline-
Polymerization was started by adding 1 g of 2-yl) propane] dihydrochloride. After polymerization for 3 hours at 60 ° C., a viscous polymer solution was obtained, and a polymer S was obtained as a dispersion stabilizer.

Synthesis Examples 2 to 9 (Polymer S) According to the composition shown in Table 1, polymer S was synthesized in the same manner as in Synthesis Example 1.

Synthesis Example 10 (Comparative Polymer) According to the composition shown in Table 1, polyvinylpyrrolidone was synthesized as a dispersion stabilizer in the same manner as in Synthesis Example 1.

[0029]

[Table 1]

As the monomer A, one having a methyl group as R ¹ in Chemical formula ¹ was used. VA-044: 2,2'-azobis [2- (2-imidazolin-2-yl) propane] dihydrochloride AIBN: 2,2'-azobisisobutyronitrile V-65: 2,2'-azobis (2,4-Dimethylvaleronitrile) NVP: N-vinylpyrrolidone HEA: 2-hydroxyethyl acrylate HEMA: 2-hydroxyethyl methacrylate DMAEMA: 2- (dimethylamino) ethyl methacrylate

Example 1 In a 500 ml four-necked flask equipped with a stirrer, a reflux condenser and a thermometer, the polymer S obtained in Synthesis Example 1 was added in a solid content of 2.
After adding 4 g and 187 g of ethanol and dissolving, ammonia water was added to adjust the pH to about 10, and the mixture was heated in a water bath at 70 ° C. for 1 hour under a nitrogen atmosphere while stirring at 120 rpm. After adding 80 g of styrene and substituting with nitrogen for about 15 minutes, 0.8 g of N, N'-azobisisobutyronitrile was added.
Addition started the polymerization. White turbidity started immediately after addition 3
It became a milky white dispersion in about 0 minutes. 72 after initiation of polymerization
The temperature is raised to ˜73 ° C. and the reaction is carried out for 4 hours, 0.4 g of N, N′-azobisisobutyronitrile is further added, and further 2
Polymerization was carried out for a time. It was confirmed by gas chromatography that the polymerization rate reached 98%. A small amount of this dispersion was set aside and the particle size distribution was measured with a Coulter counter. The average particle size was 3.2 μm and the coefficient of variation was 13
It was found to exhibit a very monodisperse particle size distribution of%.

When the obtained dispersion was left standing for 3 days, the particles settled down, and only particles could be obtained by decantation. When the slurry particles were redispersed in methanol and centrifugally sedimented at 1500 rpm for 10 minutes, all the particles were sedimented and the supernatant liquid became transparent. After washing with methanol again, filtration was performed. The filtered particles were air-dried for 24 hours and then dried under reduced pressure for 24 hours to obtain white powder polystyrene particles. The dry powder has a very high fluidity, and it was confirmed by observation with an optical microscope that the individual particles were completely independent without agglomeration.

The powdery particles were redispersed in water simply by stirring, and the particle size distribution was measured again by a Coulter counter. As a result, there were no aggregates of 2 particles or more, and the value was measured using the dispersion liquid. It showed a similar distribution.

Comparative Example 1 In a device similar to that of Example 1, the polyvinylpyrrolidone obtained in Synthesis Example 10 was added in a solid content of 8 g and ethanol in an amount of 187 g.
After the addition and dissolution, 80 g of styrene monomer was added and the temperature was raised to 70 ° C. in a water bath while stirring at 120 rpm under a nitrogen atmosphere, and 0.8 g of N, N′-azobisisobutyronitrile was added. Then, the polymerization was started. After the temperature was raised to 72 to 73 ° C. and polymerization was carried out for 4 hours, 0.4 g of N, N′-azobisisobutyronitrile was added and polymerization was further carried out for 2 hours. A small amount of this dispersion was taken and the particle size distribution was measured with a Coulter counter.

After the completion of the polymerization, the particles were washed with methanol in the same manner as in Example 1 to obtain slurry-like particles, which were more sticky and more viscous than Example 1. After air-drying for 24 hours, it was dried under reduced pressure for 24 hours to obtain white powdery polystyrene particles. The dry powder contained many aggregates of several to several tens or more polystyrene particles, and it was found by observation with an optical microscope that the particles were adhered to each other on their surfaces. Since these particles have poor redispersibility, they were redispersed by sonication in water for about 1 hour, and the particle size distribution was measured with a Coulter counter. In addition to the average particle size in the dispersion, two particles A large particle size, which is considered to be due to the above aggregation, was observed.

Comparative Example 2 Polymerization was carried out in the same manner as in Comparative Example 1. However, the polyvinylpyrrolidone obtained in Synthesis Example 10 was used in a solid content of 2.4 g. Aggregation occurred in the latter part of the polymerization, and polymer deposits were observed on the flask wall. Especially after 4 hours of polymerization, adding 0.4 g of N, N'-azobisisobutyronitrile increased the agglomerates and stirring. A fairly large lump of polymer was found on the wings. After the polymerization, the particle size distribution was measured with a Coulter counter, and a wide distribution from fine particles of 1 μm or less to particles of 6 μm or more was observed.

Examples 2 to 8 According to the compositions shown in Table 2, polystyrene particles were synthesized in the same manner as in Example 1. In each case, particles were stably synthesized. Table 3 shows the results of the particle sizes and particle size distributions of Examples 1 to 8 and Comparative Examples 1 and 2. In each of Examples 1 to 8, the fluidity of the dry particle powder was good, and neither adhesion nor aggregation of particles was observed. The redispersibility in water was also good.

[0038]

[Table 2]

[0039]

[Table 3]

(1) The particle size distribution grades were classified as follows according to the coefficient of variation of the particle size distribution. 1: 20% or less, 2: 20% or more and less than 35%, 3:35
%that's all

Example 9 The polymer S obtained in Synthesis Example 6 was placed in the same apparatus as in Example 1.
2.4 g of solid content and 187 g of ethanol were added and dissolved, and the pH was adjusted to about 10 with aqueous ammonia and 120 rpm.
The mixture was heated in a water bath at 70 ° C. for 1 hour under a nitrogen atmosphere while being stirred. Styrene 64g, n-butyl acrylate 1
6 g was added and the atmosphere was replaced with nitrogen for about 15 minutes, and 0.8 g of N, N'-azobisisobutyronitrile was added to initiate polymerization. After the addition of the initiator, the temperature was raised to 72 to 73 ° C., and the dispersion became bluish and began to become cloudy in 15 minutes, and became a milky white dispersion after 45 minutes. After the polymerization for 6 hours, 0.4 g of N, N'-azobisisobutyronitrile was added and the polymerization was further performed for 2 hours. After completion of the polymerization, the particle size distribution of the dispersion was measured with a Coulter counter to find that the average particle size was 3.2 μm.
m, and the coefficient of variation was 15%. Further, when the particles were taken out as a dry powder in the same manner as in Example 1,
It was confirmed that the individual particles exist independently without the formation of aggregates due to the adhesion of the particles to each other, and the redispersibility in water was good.

Comparative Example 3 8 g of a commercially available polyvinylpyrrolidone K-30 (manufactured by Tokyo Kasei) as a dispersion stabilizer and 187 g of ethanol were added and dissolved in the same apparatus as in Comparative Example 1, and then styrene 64 was added.
g, n-butyl acrylate 16 g, and 120 rpm
While stirring in a nitrogen atmosphere, the temperature was raised to 70 ° C. in a water bath and 0.8 g of N, N′-azobisisobutyronitrile was added.
Polymerization was carried out by adding the polymer to start the polymerization and raising the temperature to 72 to 73 ° C. Aggregation was observed in the latter stage of polymerization, and after 6 hours of polymerization, N, N
Aggregation increased when 0.4 g of'-azobisisobutyronitrile was added. After 8 hours of polymerization, the polymerization was completed, and the particle size distribution of the dispersion at the completion of the polymerization was measured with a Coulter counter and observed with a scanning electron microscope. From small particles of about 1 μm to large particles of about 13 μm. It showed a very broad particle size distribution.

Examples 10 to 16 Polystyrene-based particles having the composition shown in Table 4 were synthesized in the same manner as in Example 9. In each case, particles were stably synthesized. Table 5 shows the results of the particle sizes and particle size distributions of Examples 9 to 16 and Comparative Example 3. Examples 9-1
Regarding No. 6, no aggregates in the dry powder were observed in any case, and the redispersibility in water was good.

[0044]

[Table 4]

BA: n-butyl acrylate DVB: divinylbenzene BMA: n-butyl methacrylate MA: methyl acrylate MAA: methacrylic acid IPA: isopropanol OA: octyl alcohol

[0046]

[Table 5]

(1) The particle size distribution grades were classified as follows according to the coefficient of variation of the particle size distribution. 1: 20% or less, 2: 20% or more and less than 35%, 3:35
%that's all

[0048]

According to the production method of the present invention, a stable and sharp particle size distribution is obtained in an alcoholic medium,
Moreover, it is possible to obtain polystyrene-based particles having good redispersibility after being made into powder.

[Brief description of drawings]

1 is a scanning electron micrograph of Example 4. FIG.

Claims (7)

[Claims] 1. An average particle size of 1 μm by polymerizing a monomer B shown below in the presence of a polymer S having a monomer A shown in Chemical formula 1 in an alcoholic medium.
A method for producing monodisperse polystyrene-based particles, which comprises producing monodisperse polystyrene-based particles having a size of m or more and 20 μm or less. Embedded image (In the chemical formula 1, R ¹ represents an alkyl group having 18 or less carbon atoms or a phenyl group.) Monomer B: styrene or a mixture of styrene and a monomer copolymerizable with styrene. 2. The thiol ester group of Chemical formula 1 is converted to a mercapto group under the condition that the pH of the alcoholic medium in which the polymer S is dissolved is 8 or more and 13 or less, and then the monomer B is polymerized. The method for producing monodisperse polystyrene-based particles according to claim 1. 3. As a monomer copolymerizable with styrene, 1 to 100 parts by weight of a mixture of a monomer represented by Chemical formula 2 or a monomer having two or more double bonds in the molecule is used.
2. Use in the range of 40 parts by weight.
Alternatively, the method for producing monodisperse polystyrene-based particles according to item 2. Embedded image (In Chemical Formula 2, R ² represents a hydrogen atom or a methyl group, and R ³ represents a hydrogen atom or an alkyl group having 18 or less carbon atoms.) 4. The alcoholic medium comprises at least one alcohol selected from aliphatic alcohols or ether alcohols having 4 or less carbon atoms, water miscible with the alcohols, aromatic hydrocarbons and ethers. The method for producing monodisperse polystyrene-based particles according to claim 1, 2 or 3, which is a mixed medium containing a solvent selected from ketones in an amount of 20 parts by weight or less based on 100 parts by weight of the medium. 5. The polymer S is a copolymer containing 0.1 to 20 parts by weight of the monomer A shown in Chemical formula 1, and together with the monomer A, Chemical formula 3, Chemical formula 4, Chemical formula 5, Chemical formula 6, Chemical formula 7, Chemical formula At least one monomer C selected from the monomer group represented by 8
The method for producing monodisperse polystyrene-based particles according to any one of claims 1 to 4, which is a copolymer containing 0 to 99.9 parts by weight. Embedded image (Wherein R ⁴ is a hydrogen atom or a methyl group, R ⁵ and R ⁶
Represents a methyl group or an ethyl group, and n represents an integer of 1 to 3. ) [Chemical 4] (4 in R ⁷ is a hydrogen atom or a methyl group of, R ^8, R ⁹
Represents a hydrogen atom or an alkyl group having 4 or less carbon atoms. ) [Chemical 5] (In Chemical Formula 5, R ¹⁰ , R ¹¹ , and R ¹² represent a hydrogen atom or a methyl group, and n represents an integer of 0 to 10.) [Chemical 7] (In the chemical formula 7, R ¹³ represents a hydrogen atom or a methyl group.) 6. The method for producing monodisperse polystyrene-based particles according to claim 1, wherein 0.1 to 30 parts by weight of the polymer S is used with respect to 100 parts by weight of the monomer B. 7. The method for producing monodisperse polystyrene particles according to claim 1, wherein the weight average molecular weight of the polymer S is 10,000 or more.