JPH0694484B2 - Method for producing monodisperse polymer particles with increased particle size - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing monodisperse polymer particles having an increased particle size, and more specifically, a monomer present in a dispersion medium of seed polymer particles. The present invention relates to a method for producing polymer particles having an increased particle size by reducing the solubility of the monomer to allow the monomer to be absorbed in the seed polymer particles and performing polymerization in this state.

[Conventional technology]

Heretofore, as a method for producing spherical polymer particles, an emulsion polymerization method, a suspension polymerization method, and a dispersion polymerization method have been known. Each of these polymerization methods is characterized by the obtained particle size, particle size distribution and molecular weight, and the emulsion polymerization method can obtain high molecular weight monodisperse fine particles, but only a small particle diameter of 1.0 μm or less. On the other hand, although the suspension polymerization method can obtain particles having a large particle size of 10 μm or more, only those having a polydisperse particle size distribution can be synthesized. Furthermore, in dispersion polymerization, the particle size is 7μ.
Although it has been reported that monodisperse particles of about m have been synthesized, it is not easy to control the molecular weight and particle size of the polymer constituting the particles, and the monomers that can be used are limited.

To improve these shortcomings, Journal of Polymer Science; Polymer Symposium 72,2
25-240 (1985) proposes a "two-step swelling method" in which monodisperse particles synthesized by emulsion polymerization are swollen with an oligomer or a solvent, and then swollen with a monomer to carry out polymerization.

[Problems to be solved by the invention]

However, the above-mentioned methods of the prior art require a complicated means of two-step swelling, require a long time for the swelling operation itself, and have a problem of low productivity.

If spherical polymer particles having a particle size on the order of several μm to several tens of μm and a monodispersed particle size distribution can be obtained, this product has a sharp particle size distribution and does not require operations such as classification. It is expected to be used for toners, gap adjusting agents for liquid crystal display plates, standard particles for Coulter counters, column packings for chromatography, carriers for immunodiagnostics, and fillers for cosmetics.

Therefore, an object of the present invention is to provide a method capable of producing monodisperse polymer particles having an increased particle size with high productivity.

Another object of the present invention is to reduce the solubility of the monomer in the dispersion medium, by utilizing the monomer absorption of the seed polymer particles,
It is another object of the present invention to provide a method capable of efficiently producing large-diameter monodisperse polymer particles in a short time.

[Means for solving problems]

A water-miscible organic solvent that dissolves a monomer but does not dissolve the polymer or a mixed solution of the water-miscible organic solvent and water is used as a solvent, and the monomer has a swelling property with respect to the monomer. The seed polymer particles shown, a dispersion stabilizer and an oil-soluble polymerization initiator are dissolved or dispersed in the solvent, and the dispersion system is brought into contact with water through a semipermeable membrane to give a single amount in the seed polymer particles. Of a polymer and a polymerization initiator, and a polymer particle diameter is increased by selectively polymerizing a monomer absorbed in a seed polymer particle, and a monodisperse polymer having an increased particle diameter. A method of making particles is provided.

[Action]

In the present invention, a water-miscible organic solvent which dissolves a monomer but does not dissolve the polymer, or a mixed solution of the organic solvent and water, is used as a solvent / seed polymer particle for dissolving the monomer. It is used as a dispersion medium for dispersion. That is, in the solvent / dispersion medium used in the present invention, the decrease in the monomer solubility due to the addition of water is remarkable, and the amount of the monomer commensurate with the decrease in the solubility is forcibly absorbed into the seed polymer particles, Swelling of the polymer particles will occur. In order to cause forced swelling of the polymer particles, the seed polymer particles must of course be swellable with respect to the monomers. Also, the seed polymer particles must be present as stable and independent dispersed particles in this polymerization system, and for this purpose a dispersion stabilizer must be added to the polymerization system. Further, it is important that the initiation of polymerization is selectively carried out only for the monomer absorbed in the seed polymer particles, and if the polymerization is initiated for the monomer dissolved in the dispersion medium, the production weight The monomer is absorbed by the coalesced particles, and particle growth occurs, and it becomes difficult to obtain a monodisperse polymer particle.Therefore, the polymerization initiator is oil-soluble, and together with the monomer, a seed polymer particle is formed. Desirable to be absorbed.

The method of the present invention is, as described above, forcibly swelling the seed polymer particles with the monomer by using the decrease in the solubility of the monomer in the solvent / dispersion medium as a driving force. It is characterized in that it is brought into contact with water through a semipermeable membrane as means for reducing the solubility of the polymer. That is, water is introduced into the dispersion system through the semipermeable membrane in a relatively uniform state due to the difference in osmotic pressure,
Further, the organic solvent in the dispersion system can be discharged out of the system. In particular, discharging the organic solvent out of the system is effective in significantly reducing the number of monomers dissolved in the solvent, and is effective in preventing the monomers from polymerizing alone to form particles having a small particle size. There is.

From the above action, the semipermeable membrane passes only water and an organic solvent,
On the other hand, those which do not pass through monomers and polymerization initiators including seed polymers are desirable. However, a material such as cellophane which allows a monomer or a polymerization initiator to pass therethrough can be sufficiently used. This is because the rate of water penetration into the system is higher than the diffusion of the polymerization initiator and the monomer, so that the solubility of the monomer and the polymerization initiator is reduced and the absorption to the seed polymer is reduced. It is thought that this is because it occurs rapidly. It is also possible to apply pressure to the water side so that the monomers and the polymerization initiator do not diffuse through the membrane so that the water is forced into the dispersion system. Further, the solubility decreasing effect can be promoted by combining two or more kinds of means for lowering the temperature of the dispersion system and means for adding an electrolyte such as sodium chloride into the system.

As already pointed out, in the usual method, it is very difficult to cause the polymer particles to absorb a large amount of the monomer in a short time and to cause the swelling thereof, but according to the method of the present invention. For example, by utilizing the decrease in the solubility of the monomer in the specific solvent / dispersion medium to deposit and absorb the monomer in the seed polymer, the swelling treatment of the seed polymer particles can be performed efficiently in a short time. It can be done well. Moreover, since the monomer absorbed by the polymer particles can be selectively polymerized, the particle size can be increased, and spherical polymer particles having a monodisperse particle size distribution can be obtained.

[Preferred embodiment]

Monomer The monomer used in the present invention is an ethylenically unsaturated monomer having radical polymerizability, and suitable examples thereof include monovinyl aromatic monomer, acrylic monomer and vinyl ester monomer. Polymers, vinyl ether-based monomers, diolefin-based monomers, mono-olefin-based monomers, halogenated olefin-based monomers, polyvinyl-based monomers and the like.

The monovinyl aromatic monomer has the formula (In the formula, R ₁ is a hydrogen atom, a lower alkyl group or a halogen atom, and R ₂ is a hydrogen atom, a lower alkyl group, a halogen atom, an alkoxy group, an amino group, a nitro group, a vinyl group or a carboxyl group.) Monovinyl aromatic hydrocarbons such as styrene, α-methylstyrene, vinyltoluene, α-chlorostyrene,
O-, m-, p-chlorostyrene, p-ethylstyrene, sodium styrenesulfonate, and divinylbenzene can be used alone or in combination of two or more kinds thereof, and the above-mentioned other monomers are as follows. Are listed respectively.

formula (In the formula, R ₃ is a hydrogen atom or a lower alkyl group, R ₄ is a hydrogen atom, a hydrocarbon group having up to 12 carbon atoms, a hydroxyalkyl group,
Vinyl ester group or aminoalkyl group) acrylic monomer such as acrylic acid, methacrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, acrylic acid Phenyl, methyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, ethyl β-hydroxyacrylate, butyl γ-hydroxylate, butyl δ-hydroxyl acrylate, ethyl β-hydroxymethacrylate, γ-aminopropyl acrylate , Γ-N, N-diethylamino propyl acrylate, ethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate and the like.

formula (Wherein R ₅ is a hydrogen atom or a lower alkyl group), for example vinyl formate, vinyl acetate, vinyl propionate and the like.

formula (In the formula, R ₆ is a monovalent hydrocarbon group having up to 12 carbon atoms), for example, vinyl methyl ether, vinyl ethyl ether, vinyl-n-butyl ether, vinyl phenyl ether, vinyl cyclohexyl ether and the like.

formula (Wherein each of R ₇ , R ₈ and R ₉ is a hydrogen atom, a lower alkyl group or a halogen atom), particularly butadiene, isoprene, chloroprene and the like.

formula (Wherein each of R ₁₀ and R ₁₁ is a hydrogen atom or a lower alkyl group), especially ethylene, propylene, isoprene, butene-1, pentene-1, 4-methylpentene-1 and the like.

Examples of halogenated olefin monomers include vinyl chloride and vinylidene chloride, and examples of polyvinyl monomers include divinylbenzene, diallyl phthalate,
Examples include triallyl sialate.

These monomers may be used alone or in combination of two or more. Suitable monomers are styrene, (meth) acrylic acid esters, styrene / (meth) acrylic acid esters, styrene / divinylbenzene.

Organic solvents Water-miscible organic solvents include methanol, ethanol,
Lower alcohols such as isopropanol; polyhydric alcohols such as ethylene glycol, propylene glycol, butanediol, diethylene glycol, triethylene glycol; cellosolves such as methyl cellosolve and ethyl cellosolve; ketones such as acetone and methyl ethyl ketone; ethers such as tetrahydrofuran Examples include esters such as ethyl acetate; organic acids such as formic acid, acetic acid, and propionic acid. Of these, those in which the monomer dissolves but the polymer does not dissolve Used in combination. An organic solvent which is excellent in the solubility of the monomer and which can be mixed with water at an arbitrary ratio and therefore is particularly useful for the purpose of the present invention is a lower alcohol such as ethanol.

This water-miscible organic solvent can be used alone,
It can also be used in the form of a mixed solution with water. In this latter case, it is desirable to contain water as much as possible within a range that does not practically reduce the solubility of the monomer, and the mixing ratio is determined by the monomer and the organic solvent used. When a lower alcohol is used as the solvent, the organic solvent and water can be used in a volume ratio of 10: 1 to 3: 5, particularly 4: 3 to 3: 4.

Seed Polymer Particles The seed polymer particles used in the present invention are swellable with respect to the above-mentioned monomers, and are polymer particles obtained by polymerizing one or more of the above-mentioned monomers. Is. The polymer particles are generally formed from the same kind of monomer as the monomer used, but may be formed by polymerization of a monomer different from this monomer. The former example is a combination of styrene polymer particles and a styrene monomer, and the latter example is a combination of acrylic polymer particles and a styrene monomer.

The seed polymer particles have a monodisperse particle size distribution,
The particle size is generally 0.01 to 50 μm, especially 0.5 to 20 μm
It is desirable to be within the range. Such seed polymer particles can be easily obtained by a known dispersion polymerization method, emulsion polymerization method, or by pulverizing and classifying the polymer.

Dispersion stabilizer As a dispersion stabilizer for improving the dispersibility of the seed polymer particles in the solvent and dispersion medium, known per se, polyvinyl alcohol, methyl cellulose, ethyl cellulose,
Polymer dispersion stabilizers such as polyacrylic acid, polyacrylic imide, polyethylene oxide, poly (hydroxystearic acid-g-methyl methacrylate-co-methacrylic acid) copolymer, nonionic surfactants, anionic interfaces Activators, cationic surfactants, amphoteric surfactants and the like are used.

Among these, polymer dispersion stabilizers such as polyvinyl alcohol are suitable, and give good results when combined with an organic solvent-water mixture.

Polymerization Initiator Any polymerization initiator can be used as long as it is oil-soluble. For example, as a radical polymerization initiator,
Suitable for azo compounds such as azobisisobutyronitrile and monomers such as cumene hydroperoxide, t-butyl hydroperoxide, dicumyl peroxide, di-t-butyl peroxide, benzoyl peroxide and lauroyl peroxide. A melt is used. Further, in the case of polymerization by ultraviolet rays, an oil-soluble photopolymerization initiator known per se can be used. Among the oil-soluble ones, it is particularly preferable to use a polymerization initiator which is hardly dissolved in the organic solvent so that the monomer is difficult to polymerize alone in the organic solvent.

Semipermeable membrane As a semipermeable membrane, cellophane, collodion membrane, sulfuric acid paper, cellulose membrane, cellulose derivative membrane, acrylonitrile-
Dialysis membranes such as sodium methacryl sulfonate copolymer membranes, polycarbonate-polyether block copolymer membranes, ethylene-vinyl alcohol copolymer membranes; cellulose acetate membranes such as cellulose acetate and cellulose acetate sulfate, polyamide hydrazides, polypiperazine Polyamide-based membranes such as amides and m-phenylisophthalamide-terephthalamide copolymers, polyethyleneimine-based membranes, polyethyleneoxide-based membranes, pylon, polybenzimidazolone,
Reverse osmosis membranes such as polyimide; ultrafiltration membranes such as cellulose dioxide, polybenzoxazinedione sulfonated, polyamide-imide, etc., which are relatively small in permeation, and the like can be arbitrarily used.

Polymerization Method According to the present invention, first, a monomer, seed polymer particles, a dispersion stabilizer, and a polymerization initiator are dissolved or dispersed in a water-miscible organic solvent or a mixed solution of the water-miscible organic solvent and water.

The concentration of seed polymer particles in the dispersion is generally 0.01 to
It is preferably used in an amount of 50% by weight, particularly 0.1 to 20% by weight. The amount of the monomer added also differs depending on the desired degree of increase in particle size.

That is, n ³ times as many monomers are needed to increase the particle size of the seed polymer by n times. The seed polymer particles and the monomers in the system are generally preferably present in a weight ratio of 1: 1 to 1:10 ^9, particularly 1:10 to 1:10 ⁶ .

The dispersion stabilizer is preferably used in an amount of 0.1 to 30% by weight, particularly 1 to 10% by weight, based on the seed polymer particles, while the polymerization initiator is 0.001 to 10% by weight, particularly 0.01 It is preferable to use it in an amount of from 0.5 to 0.5% by weight.

By bringing this dispersion system into contact with water through the semipermeable membrane, substantially all of the charged monomers can be deposited and absorbed in the seed polymer particles. Generally, it is desirable that 50% by weight or more, especially 90% by weight or more of the charged monomers be absorbed in the seed polymer particles. It is a remarkable feature of the present invention that this treatment is carried out within an extremely short time, and the absorption of the polymerization initiator is carried out simultaneously with the absorption of the monomer.

As a method of contacting the dispersion with water, a means of putting water filled in the dispersion into the dispersion, a means of partitioning with a semipermeable membrane in water, a partition with a semipermeable membrane There is a means such as putting the dispersion system and water into the container at the same time, but increase the contact area per volume of the dispersion system so that the water diffuses as uniformly as possible in the dispersion system, and the dispersion system flows. Therefore, it is desirable to provide a stirring means. Moreover, for example, if a tubular device is partitioned by a semipermeable membrane and water and a dispersion system are contacted by convection, efficient continuous production can be achieved.

Next, the monomer absorbed in the polymer particles is polymerized.
Polymerization is generally performed at -30 ° C to 90 ° C in an inert atmosphere such as nitrogen.
It is carried out at a temperature of ℃, especially 30 ℃ to 80 ℃. The polymerization conditions differ depending on the type of the polymerization initiator, and for example, a photopolymerization initiator may be irradiated with light having an appropriate wavelength. If the polymerization initiator reacts at a low temperature, the polymerization of the monomer may start at the same time as absorption into the seed polymer, but it is better to start the polymerization after the absorption has been completed. Is more desirable because there is no danger of polymerizing by itself to form particles with a small particle size.

The polymerization time is such that the absorbed monomer is completely polymerized, and generally 0.1 to 30 hours is appropriate. The method of the present invention may be carried out in only one step, or may be carried out in a plurality of steps until it grows to a predetermined grain size. The resulting polymer generally has a particle size of 1 to 1000 μm, especially 5 to 100 μm.
It has the characteristics of being highly monodisperse. The obtained polymer particles can be used for various purposes in the form of suspension, or can be used for various purposes in the form of powder after being separated by filtration and washed with water if necessary.

〔Example〕

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

(Example 1) Styrene 20 ml, deionized water 36 ml, ethanol 144 ml,
Azobisisobutyronitrile 284mg and polyacrylic acid 2
The mixed solution of g was placed in a 3-necked separable flask equipped with a reflux condenser, and the mixture was stirred at 100 rpm under a nitrogen stream at 12 ° C at 70 ° C.
The reaction was allowed to proceed for a period of time to complete the polymerization. The polymer was observed by an optical microscope and found to be monodisperse particles of about 2 μm. 0.4 g of the polymer synthesized in this manner was added to 70 g of ethanol, 70 g of ion-exchanged water, 3 g of styrene, and 0.1 g of polyvinyl alcohol.
An emulsion was obtained by dispersing in 5 g and a solution of 2,2'-azobis (2,4-dimethylvaleronitrile) 0.15 g.

As shown in FIG. 1, a cellulose acetate film 4 was provided on the outside of an aluminum colander-like container 3 and was attached to the upper end 3a of the container 3 with a vinyl tape. This container was gently inserted into a water tank 2 containing ion-exchanged water 1 and a stirring device 5 was provided. When the emulsion is gently poured into the container 3 while rotating the stirring device 5 before water enters the cellophane, the ion-exchanged water 1 in the water tank 2 enters the container 3,
The water level in the container 3 rose rapidly.

When the emulsion was observed with an optical microscope in this state, the particles were swollen into a spherical shape of about 8 μm. This emulsion was placed in a 300 ml three-necked flask equipped with a reflux condenser, and reacted at 70 ° C. for 8 hours while stirring at 100 rpm in a nitrogen stream to complete the polymerization reaction.

The polymer obtained from the above reaction was filtered and then dried to 3 g.
Resin fine particles of The filtrate was almost clear. When the particle size distribution of the obtained particles was measured by a Coulter counter, as shown in Table 1, the particles were very monodisperse and spherical particles having an average particle size of 7.7 μm.

(Example 2) 14 ml of styrene, 6 ml of butyl acrylate, 36 m of ion-exchanged water
l, ethanol 144 ml, azobisisobutyronitrile 280
g and 2 g of polyacrylic acid were placed in a 300 ml three-neck separable flask equipped with a reflux condenser, and reacted at 70 ° C. for 12 hours while stirring at 100 rpm under a nitrogen stream to complete the polymerization.
When the polymer was observed with an optical microscope, it was found to be monodisperse particles of about 2 μm.

0.4 g of the polymer obtained above was dispersed in a solution consisting of 70 g of methanol, 70 g of ion-exchanged water, 20 g of styrene, 0.3 g of polyvinyl alcohol and 0.15 g of benzoyl peroxide to obtain an emulsion.

As shown in FIG. 2, the U-shaped tube 10 is attached to the cellulose diacetate membrane 11
Then, ion-exchanged water is injected from one side, and the emulsion is injected from the other side at the same time. A pressure of 10 g / cm ² is applied to the ion-exchanged water side, and a stirrer piece 12 is put on the emulsion side and stirred with a magnetic stirrer 13. When the water level on the emulsion side stopped increasing, the emulsion was observed with an optical microscope to find that the particles had swollen to a spherical shape of about 14 μm. This emulsion was placed in a 200 ml three-neck separable flask equipped with a reflux condenser, and reacted at 70 ° C. for 8 hours while stirring at 100 rpm in a nitrogen stream to complete the polymerization.
The polymer was filtered and dried to obtain 16 g of resin particles.
The filtrate was almost clear. When the particle size distribution of the resin particles was measured by a Coulter counter, as shown in Table 2, the particles were very monodisperse and spherical particles having an average particle size of 13.8 μm.

(Example 3) 20 ml of styrene, 36 ml of deionized water, 144 ml of ethanol,
A mixed solution of 284 mg of 2.2'-azobisisobutyronitrile and 2 g of polyacrylic acid was placed in a 3-necked separable flask equipped with a reflux condenser, and stirred under a nitrogen stream at 100 rpm while stirring.
Polymerization was completed by reacting at 12 ° C for 12 hours. The polymer was observed by an optical microscope and found to be monodisperse particles of about 2 μm. 0.4 g of the polymer thus obtained was added to ethanol 30
g, ion-exchanged water 50 g, methyl methacrylate 3 g, lauryl trimethyl ammonium chloride 0.15 g and 2.2'-
It was dispersed in a solution consisting of 0.15 g of azobis- (2.4-dimethylvaleronitrile).

As shown in FIG. 3, ion-exchanged water 21 is put in the water tank 20, and the central part of the cellophane tube (made by Wako Pure Chemical Industries, Ltd.) 22 is put in the water tank.
It was submerged in 20 and the above emulsion was injected from one end. When the liquid flowing out from the other end was taken in a beaker and observed with an optical microscope, the particles were swelled in a pearl shape to about 8 μm.
This emulsion was placed in a 300 ml 3-neck separable flask equipped with a reflux condenser, and reacted at 70 ° C. for 8 hours while stirring at 100 rpm in a nitrogen stream to complete the polymerization. The polymer was filtered and then dried to obtain 3 g of resin particles. The filtrate was slightly cloudy. When the particle size distribution of the obtained resin particles was measured by a Coulter counter, they were very monodisperse and spherical particles having an average particle size of 7.4 μm as shown in Table 3.

Example 4 20 ml of methyl methacrylate, 36 ml of ion-exchanged water, 144 ml of isopropyl alcohol, 200 mg of 2.2'-azobisisobutyronitrile and 2 g of polyacrylic acid were added to a 300 ml three-neck separable flask equipped with a reflux condenser. Then, the mixture was reacted at 70 ° C. for 12 hours while stirring at 100 rpm in a nitrogen stream to complete the polymerization. When the polymer was observed with an optical microscope, it was found to be monodisperse particles of about 1 μm.

0.1 g of the polymer obtained above was added to isopropyl alcohol 40
g, ion-exchanged water 100 g, methyl acrylate 20 g, polyacrylic acid 0.15 g and 2.2'-azobisisobutyronitrile 0.
Dispersed in a solution consisting of 15 g. Next, the cellulose acetate membrane in the apparatus used in Example 1 was changed to an ethylene-vinyl alcohol copolymer membrane, and the particles in the emulsion were swollen.

When the emulsion was observed under an optical microscope in this state, the particles were swollen by about 13 μm. This emulsion was placed in a 300 ml three-neck separable flask equipped with a reflux condenser, and reacted at 70 ° C. for 8 hours while stirring at 100 rpm in a nitrogen stream to complete the polymerization. The polymer was filtered and then dried to obtain 20 g of resin particles. The filtrate was almost clear. When the particle size distribution of the obtained resin particles was measured by a Coulter counter, they were very monodisperse spherical particles having an average particle size of 12.5 μm as shown in Table 4.

(Example 5) 90 ml of butyl acrylate, 320 ml of ion-exchanged water and potassium persulfate were placed in a 500 ml three-necked separable flask equipped with a reflux condenser and stirred at 150 rpm under a nitrogen stream at 70 ° C.
The reaction was allowed to proceed for 24 hours to complete the polymerization. When the particles of the polymer were observed with a transmission electron microscope, they were monodisperse particles of about 0.6 μm.

1 mg of the polymer obtained above was mixed with 70 g of methanol and ion-exchanged water.
70g, styrene 4g, polyvinyl alcohol 0.2g and 2.2 '
-Azobis- (2.4-dimethylvaleronitrile) was dispersed in a solution consisting of 0.15 g. Next, in the apparatus used in Example 2, the cellulose diacetate membrane was replaced with a polybenzoxazinedione membrane to swell the particles in the emulsion. When the emulsion was observed with an optical microscope, the particles were found to be spherical and swelled to about 15 μm.

The above emulsion was placed in a 200 ml three-neck separable flask equipped with a reflux condenser and reacted at 70 ° C. for 8 hours while stirring at 100 rpm under a nitrogen stream to complete the polymerization. The polymer was filtered and dried to obtain 3 g of resin particles. The filtrate was almost clear. When the particle size distribution of the obtained resin particles was measured by a Coulter counter, the particles were very monodisperse spherical particles having an average particle size of 15.0 as shown in Table 5.

(Example 6) Styrene 150 g, ion-exchanged water 600 g, potassium persulfate 0.3 g
Then, 0.3 g of polyoxyethylene sorbitan monolate was placed in a 3-neck separable flask equipped with a reflux condenser, and reacted at 70 ° C. for 12 hours while stirring at 150 rpm under a nitrogen stream to complete the polymerization. When the particles of the obtained polymer were observed with a transmission electron microscope, they were monodisperse particles of about 0.8 μm.

The polymer particles 1 mg obtained above methanol 70 g, ion-exchanged water 70 g, styrene 4 g, sodium laurate 0.2 g and
2.2'-Azobisisobutyronitrile was dispersed in a solution of 0.15 g to obtain an emulsion. Next, the particles in the emulsion were swollen in the same manner as in Example 1. When the emulsion was observed with an optical microscope, the particles were swollen to about 20 μm. Then, the emulsion was irradiated with ultraviolet rays by an ultraviolet lamp for 30 hours to complete the polymerization reaction.

The polymer obtained above was filtered and then dried to obtain 4 g of resin fine particles. The filtrate was clear. Then, the particle size distribution of the obtained resin particles was measured with a Coulter counter, and as shown in Table 6, monodispersed spherical resin particles having an average particle size of 19.7 μm were obtained.

(Example 7) Polystyrene resin was pulverized and classified to obtain resin particles having a particle size distribution shown in Table 7 and an average powder diameter of 1.75 µm. 0.04 g of the resin particles were dispersed in a solution of 70 g in ethanol, 70 g of ion-exchanged water, 12 g of styrene, 0.15 g of polyvinyl alcohol and 0.15 g of 2.2'-azobis- (2.4-dimethylvaleronitrile) to give an emulsion.

Next, the particles in the emulsion were swollen in the same manner as in Example 1. When this emulsion was observed with an optical microscope, the particles were swollen into a spherical shape of about 11.5 μm. To this emulsion at -10 ° C, 50 g of ion-exchanged water at 0 ° C was added all at once, and the mixture was placed in a 300 ml three-necked separable flask equipped with a reflux condenser and reacted at 70 ° C for 8 hours while stirring at 100 rpm under a nitrogen stream. To complete the polymerization.

The obtained polymer was filtered and then dried to obtain about 10 g of resin particles. The filtrate became slightly cloudy. When the particle size distribution of the obtained resin particles was measured with a Coulter counter,
As shown in Table-8, the average monodisperse particle size is 11.5 μm.
It was a spherical particle.

Table 8 shows the particle size distribution of the resin particles thus obtained and the polystyrene resin prepared by using a pulverizer (IDS-2, manufactured by Nippon Pneumatic Co., Ltd.) and having an average particle diameter of 11.6μ, which is measured by a Coulter counter. Write down the value.

From the table, it can be seen that the resin particles obtained by polymerization are much more monodispersed than those obtained by crushing.

Effects of the Invention According to the present invention, it is possible to effectively reduce the solubility of the monomer in the water-miscible organic solvent that is a solvent for the monomer and a dispersion medium for the seed polymer particles. By allowing the polymer particles to absorb an amount of the monomer commensurate with this decrease, it became possible to efficiently swell the seed polymer particles with the monomer within an extremely short time. . Further, since the monomer absorbed by the seed polymer particles is polymerized with good selectivity, the monodisperse polymer particles having an increased particle size are used as standard for electrophotographic toner, liquid crystal display gap adjuster, and Coulter counter. It can be supplied at low cost for uses such as particles, column fillers for chromatography, immunodiagnostic carriers, cosmetic fillers, and the like.

Furthermore, according to the production method of the present invention, colored particles can be easily produced by simply adding an oil-soluble dye to the dispersion system, and the monodisperse colored polymer thus obtained is used as a cosmetic product or the like. The colored fine particles can be directly used in each field.

Further, in addition to the dye, by adding a substance that adds a function to the particles, for example, by adding an oil-soluble fragrance or the like, it is possible to obtain particles having a scent. You can In addition, the additive must be easily incorporated into the seed polymer together with the monomer.

[Brief description of drawings]

1 to 3 show an embodiment of means for absorbing a monomer into seed polymer particles in the present invention.

Claims (1)

[Claims] 1. A water-miscible organic solvent which dissolves a monomer but does not dissolve the polymer or a mixed solution of the water-miscible organic solvent and water as a solvent, On the other hand, the seed polymer particles showing swelling property, the dispersion stabilizer and the oil-soluble polymerization initiator are dissolved or dispersed in the solvent, and the dispersion system is brought into contact with water through a semipermeable membrane to give a seed polymer. Increasing the particle size characterized by increasing the polymer particle size by absorbing the monomer and the polymerization initiator in the particles and selectively polymerizing the monomer absorbed in the seed polymer particles For producing the monodisperse polymer particles described above.