JPS62227902A - Production of solvent-resistant porous fine particle of uniform particle diameter - Google Patents

Abstract

PURPOSE:To produce the titled fine particles excelling in solvent resistance and having a uniform particle diameter, by extracting solvent-soluble matter from a specified precursor of porous fine crosslinked polymer particles. CONSTITUTION:A monomer mixture comprising 99-99.95wt% noncrosslinking monomer and 1-0.05wt% crosslinking monomer is added to an aqueous dispersion of uncrosslinked fine polymer particles of a particle diameter of 0.5-2mum and a standard deviation of a particle size distribution <=0.1mum, obtained by forming an uncrosslinked polymer by polymerizing a mixture containing water, an emulsifier, a surfactant and a noncrosslinking monomer and increasing the diameter of the polymer particles by repeating such polymerization at least twice by using the polymer as initial seed particles, and the resulting mixture is polymerized to obtain crosslinked fine polymer particles. 100-3,000pts.wt. monomer mixture comprising 50-90wt% noncrosslinking monomer and 50-10wt% crosslinking monomer and 100-6,000pts. wt. pore modifier are absorbed by 100pts.wt. above produced fine particles and copolymerized in an aqueous medium to obtain a precursor of crosslinked porous fine polymer particles. Solvent-soluble matter is extracted from this precursor to obtain solvent-resistant porous fine particles having a uniform diameter, a particle diameter of 2-30mum and a standard deviation of a particle size distribution <=1mum.

Description

Detailed Description of the Invention: Industrial Field of Application The present invention provides a porous crosslinked polymer comprising non-crosslinked polymer fine particles, a pore control agent, a crosslinked T12 polymer with a low crosslinking density, and a crosslinked polymer with a high crosslinking density. A method for producing fine particles of uniform particle size that are 2 to 30 μm in diameter, have a standard deviation of particle size distribution of 1+7+n or less, are solvent resistant, and are porous, and are characterized by removing solvent-soluble substances from a precursor of the fine particles. Regarding the manufacturing method.

BACKGROUND OF THE INVENTION Polymer fine particles used as opacifying agents, matting agents, organic pigments or fillers, thickness and gap adjusting agents, carriers for chromatography, etc. are strongly required to have uniform particle diameters. Furthermore, when used in a dispersed state in various solvents, such as when used as a thickness gap adjustment material or a carrier for chromatography, it is required that the material does not dissolve or swell in the solvent. Furthermore, in applications where a large surface area is advantageous, such as when used as a carrier for chromatography or a carrier for various substances, porous properties are also desired.

Conventionally, methods for producing solvent-resistant, uniformly sized fine particles include:
A method was known in which polymer fine particles in a crosslinked state were used as seed particles, and a non-crosslinking monomer or a mixture of crosslinking monomers was absorbed into the seeds for polymerization treatment (Japanese Unexamined Patent Application Publication No. 1983-1993).
18705, British Patent No. 728508, British Patent No. 1116800).

On the other hand, as a method for producing porous particles of uniform particle size, a hydrophilic vinyl monomer and acrylic acid, etc. are mixed in the presence of an organic solvent that dissolves the monomers used but does not dissolve the reaction product. , or a method of polymerizing a phenyl group-containing hydrophobic monomer and a hydrophilic monomer in aqueous suspension and then removing the organic solvent is known, as disclosed in JP-A-58-88657;
(Japanese Unexamined Patent Publication No. 58-83260).

Problems to be Solved by the Invention However, in any of the above-mentioned methods for simply obtaining solvent-resistant particles, there is a problem in that the resulting fine particles have poor uniformity in particle size.

Further, even in the aqueous suspension polymerization method for obtaining porous materials, there is a problem that the particle size distribution of the resulting particles is wide (several microns to several tens of microns) and is poor in uniformity.

As described above, it has been difficult to obtain fine particles with excellent uniformity in particle size using conventional methods. Therefore, the current practice is to perform a classification process after polymerization to make the particle size uniform. However, classification processing has not yet been carried out so that the standard deviation of the particle size distribution is 1 μm or less in the particle size range of 2 to 30 μm.

Therefore, no method has been known to date for producing solvent-resistant, porous, uniformly sized fine particles having a particle size of 2 to 30 uII and a standard deviation of particle size distribution of 1 μm or less.

Means for Solving the Problems The present inventors have overcome the above problems, and the particle size is 2 to 30 μm.
As a result of intensive research to develop a manufacturing method that can obtain solvent-resistant and porous uniform-sized fine particles without classification, the standard deviation of the particle size distribution is 1 μm fl or less. Non-crosslinked polymer fine particles whose particle size has been grown using a seed polymerization method are first treated with a monomer mixture containing a low concentration of crosslinkable monomers, and then crosslinked into the resulting crosslinked polymer fine particles. Infiltrating a monomer mixture with a high concentration of polypropylene monomers and a pore control agent, copolymerizing them, and extracting and removing solvent-soluble substances from the obtained precursor of porous crosslinked polymer fine particles. The inventors have discovered that the object can be achieved by the following methods, and have come up with the present invention.

That is, the present invention includes (A) adding water and a non-crosslinking monomer to an aqueous dispersion of seed particles, polymerizing them, and using the obtained particles as the next seed particle to further grow the diameter. , obtained by repeating a non-crosslinked polymer obtained by treating a non-crosslinkable monomer in an aqueous medium twice or more as initial seed particles,
The particle size is 0.5 to 2 μm and the standard deviation of particle size distribution is 0. lu
99 to 99.95% by weight of a non-crosslinkable monomer and 1 to 0% by weight of a crosslinkable monomer to an aqueous dispersion of non-crosslinked polymer fine particles of +n or less.
A monomer mixture consisting of 0.05% by weight was added and polymerized,
In the obtained crosslinked polymer fine particles, non-crosslinkable monomer 5
A monomer mixture consisting of 0 to 90% by weight and 50 to 10% by weight of a crosslinkable monomer and a pore regulator are absorbed and copolymerized in an aqueous medium to form a precursor of porous crosslinked polymer fine particles. and (B) extracting a solvent-soluble substance from the precursor of the porous crosslinked polymer fine particles obtained in the above step, the particle size is 2 to 30 μm and the standard deviation of the particle size distribution is 111111 or less. , provides a method for producing solvent-resistant, porous, uniformly sized fine particles.

In the method of the present invention, first, non-crosslinked polymer fine particles obtained by a seed polymerization method are treated with a monomer mixture containing a low concentration of crosslinkable monomers, and the resulting crosslinked polymer fine particles contain crosslinkable polymer particles. A monomer mixture containing a high concentration of monomers and a pore adjusting agent are absorbed and copolymerized to obtain a precursor of porous crosslinked polymer fine particles (Step A).

In this case, the non-crosslinked polymer fine particles are obtained by repeating seed polymerization twice or more, have a particle size of 0.5 to 2 μI, and have a standard deviation of particle size distribution of 0.0 lum or less, preferably 0.05 μm.
The following are used: That is, an aqueous dispersion of seed particles is mixed with water, a non-crosslinking monomer, and, if necessary, an emulsifier in an amount necessary to stabilize the reaction (with a surface tension of 55 dynes/
It is preferable to set the distance to be at least cm. ) and a polymerization initiator, polymerization treatment is performed, and (4) the particles are used as the next seed particles to further grow the diameter, which is repeated two or more times to obtain a predetermined size.

As the initial seed particles, a non-crosslinked polymer obtained by treating a non-crosslinkable monomer in an aqueous medium is used. That is, for example, a non-crosslinked monomer, a non-crosslinked polymer in an emulsion obtained by processing a conventional emulsion polymerization method, etc. are used. By using non-crosslinked polymer fine particles that satisfy these conditions, the standard deviation of the particle size and particle size distribution in the final target product can be achieved.

The above-mentioned non-crosslinked polymer fine particles are subjected to treatment with a 4-mer mixture containing a low concentration of crosslinkable monomer. That is, the non-crosslinked polymer fine particles contain 99 to 99.95% by weight, preferably 99.5 to 99.95% by weight of the non-crosslinkable monomer in the aqueous dispersion.
A monomer mixture consisting of 9.9% by weight and a crosslinkable monomer of 1 to 0.05% by weight, preferably 0.5 to 0.1% by weight is added, and this is absorbed into the non-crosslinked polymer fine particles. The polymer is then polymerized to form crosslinked polymer fine particles. This makes it possible to swell with a monomer mixture containing a high crosslinking monomer content or its constituent monomers to be used later. In addition, it is possible to obtain a final target product that generally has excellent sphericity. The swelling degree (the volume ratio of the particles before and after swelling) of the crosslinked polymer fine particles obtained using the monomer mixture having the above-mentioned mixing ratio is usually 8 to 100. A material with a degree of swelling of this level is preferable in the method of the present invention. Therefore, if the content of the crosslinkable monomer in the monomer mixture used in the above treatment is too low, a product with an excessive degree of swelling will be obtained, and the solvent resistance of the final target product, uniform particle size fine particles, will be reduced. On the other hand, if the content of the crosslinkable monomer is too high, a product with an insufficient degree of swelling (excessive crosslinking density) may be obtained.
The purpose of the method of the present invention is that the 112-body mixture used later cannot be sufficiently diffused into the particles, resulting in insufficient polymerization in the particles, and new particles are likely to be generated, which causes variation in particle size. has been fully achieved.

The amount of the monomer mixture used in the treatment for converting the non-crosslinked polymer fine particles into crosslinked polymer fine particles is not limited, but is not more than 2000 parts by weight per 100 parts by weight of the non-crosslinked polymer fine particles. , particularly preferably 1000 parts by weight or less. If the amount used is excessive, the resulting crosslinked polymer fine particles may have a wide particle size distribution, and the object of the present invention may not be achieved.

In addition, when adding the monomer mixture to the aqueous dispersion of non-crosslinked polymer fine particles, it may be added as an emulsion to facilitate absorption into the non-crosslinked polymer fine particles. In this case, it is more preferable to use an oil-soluble polymerization initiator dissolved in the monomer mixture.

Based on the monomer mixture (non-crosslinked polymer fine particles are modified with a crosslinked polymer having a low crosslink density), the crosslinked polymer fine particles are a monomer mixture with a high concentration of crosslinkable monomers. That is, the monomer mixture and the pore control agent are absorbed into crosslinked polymer fine particles, and then subjected to a copolymerization treatment in the presence of a polymerization initiator. As a result, the crosslinked polymer fine particles having a crosslinked polymer with a low crosslinking density are changed, based on a monomer mixture with a high concentration of crosslinkable monomers (with a crosslinked polymer having a high crosslinking density). A precursor of porous crosslinked polymer fine particles having an expanded particle size and containing a pore regulating agent at least inside can be obtained, and a final target product having a large specific surface area can be obtained.

The filtration treatment involves absorbing a monomer mixture and a pore-adjusting agent into cross-linked polymer fine particles. A common method is to add a conditioning agent and stir. This method has the advantage that the copolymerization process can be carried out in a series using a preparation solution of crosslinked polymer fine particles. However, the method is not limited to this, and any method may be used as long as the absorption state is formed as a result. The monomer mixture and the pore regulating agent may be added as a mixture, or may be added separately, or may be added in combination. Therefore, the monomer mixture and the pore control agent may or may not be present in a mixed and integrated state in the crosslinked polymer fine particles. Further, during the absorption treatment, heating may be performed to increase the absorption rate, or a water-soluble solvent such as acetone or ethanol may be added. Furthermore, the monomer mixture and the pore regulator may be emulsified in advance and added. In addition, in a method using a solvent, it is preferable to remove the solvent before starting the polymerization.

The appropriate amount of the monomer mixture used in the treatment for obtaining the precursor of the porous crosslinked polymer fine particles described above is 100 to 3000 parts by weight per 100 parts by weight of the crosslinked polymer fine particles. If the amount used is less than 100 parts by weight, the resulting fine particles of uniform particle size will have insufficient solvent resistance,
If the amount exceeds 0 parts by weight, polymerization outside the crosslinked polymer particles tends to proceed undesirably.

Non-crosslinking monomer and crosslinking property in the monomer mixture! J
The appropriate mixing ratio with the L-mer is 50 to 90% by weight of the non-crosslinking monomer and 50 to 10% by weight of the crosslinking 11 monomer. If the mixing ratio of the crosslinkable monomer exceeds 50% by weight, the crosslinking density of the crosslinked polymer will be too high, and if it is less than 10% by weight, the crosslinking density will be too low, making it difficult to achieve the object of the present invention.

In the present invention, the monomer in the non-crosslinking monomer for obtaining non-crosslinked polymer fine particles, or the monomer mixture for obtaining the precursor of crosslinked polymer fine particles or porous crosslinked polymer fine particles is , those which themselves or their polymers are poorly soluble or insoluble in water are preferably used. If the material is easily soluble in water, polymerization will proceed in water, causing the particle size of seed particles to grow (harden), new particles to form (or become crosslinked in non-crosslinked polymer fine particles). This is not preferable because it may be difficult to absorb into the polymer fine particles of the system.

Preferably used non-crosslinking monomers include styrenic monomers such as styrene, methylstyrene, and ethylstyrene, butyl acrylate, butyl methacrylate,
Examples include acrylic acid and methacrylic acid ester monomers having an alkyl group having 4 or more carbon atoms, such as 2-ethylhexyl acrylate and 2-ethylhexyl methacrylate.

Examples of crosslinking monomers that can be preferably used include monomers having two or more ethylenic double bonds, such as trimethylolpropane trimethacrylate, diethyl glycol dimethacrylate, and divinylbenzene.

Only one non-crosslinking monomer and crosslinking monomer may be used, or 2fff1 or more may be used.

Determined according to the intended use of the object. For example, when used as a thickness gap adjustment material or a carrier for chromatography, pressure resistance is required, so a styrene monomer with a high polymer glass transition point is used as a non-crosslinking monomer,
It is preferable to use divinylbenzene, which has low solubility, as the crosslinking monomer. Incidentally, the styrene-based polymer also has the advantage that the copolymerization process can proceed stably without agglomeration.

The appropriate amount of the pore regulator used is 100 to 6,000 parts by weight per 100 parts by weight of the crosslinked polymer fine particles. In general, it is determined based on the monomer mixture with a high concentration of crosslinkable monomer used, and although it varies depending on the type of monomer, it is usually 10 to 350% by weight, preferably 10 to 350% by weight based on the monomer mixture. 50-250% by weight. If the amount used is less than 10% by weight, the pores formed may be too small, resulting in the resulting uniform particle size fine particles having poor porous properties. If the amount used exceeds 350% by weight, pores may be formed. In some cases, the pores formed become too large, and the inside of the resulting fine particles of uniform particle size becomes hollow, forming a hollow object. Therefore, from the viewpoint of porosity, pore control agents that are undesirable include solvents that can be used in the subsequent extraction process. A removable substance is used as the dissolved substance. In general, those that have a solubility in water of 1% by weight or less at room temperature (water-insoluble) and are soluble in the non-crosslinkable monomer and/or crosslinkable monomer used are used.The solubility is 1% by weight or less. If it exceeds 100%, it may not be absorbed into the crosslinked polymer fine particles and may remain in the aqueous medium, not contributing to the formation of porosity, or inhibiting the stability of the reaction system.

Specific examples of pore control agents include saturated hydrocarbons such as hexane, heptane and isooctane, aromatic hydrocarbons such as toluene, xylene and edylhensen, n-hexyl alcohol, n-octyl alcohol and 2-ethylhexyl alcohol. Examples include linear polymers such as alcohols, polystyrene, and liquid paraffin. Only one type of pore adjusting agent may be used, or two or more types may be used in combination.

The copolymerization treatment for obtaining a precursor of porous crosslinked polymer fine particles can be carried out using an appropriate medium under usual polymerization treatment conditions. When using an aqueous medium, a common oil-soluble radical initiator is preferably used as the polymerization initiator.

If it is water-soluble, new particles may be generated, which may cause problems. Note that it is preferable to use the oil-soluble polymerization initiator dissolved in the monomer mixture in an amount of 0.1 to 5% by weight in order to smoothly carry out the polymerization in the crosslinked polymer fine particles.

Incidentally, during the copolymerization treatment, it is desirable to stabilize the particles using an emulsifier or a polymerization stabilizer.

It is appropriate that the amount used is such that no new particles are generated other than the precursor of the porous crosslinked polymer fine particles.

By carrying out the copolymerization treatment as described above, a structure having a pore regulating agent and a crosslinked polymer with a high crosslink density inside the crosslinked polymer fine particles has a particle size of 2 to 30 μm, preferably 2 to 20 μm, A precursor of porous crosslinked polymer fine particles having a standard deviation of particle size distribution of l jun or less, preferably 0.5 μm or less, and generally having excellent sphericity can be obtained.

Note that the crosslinked polymer having a high crosslink density in the precursor of the porous crosslinked polymer fine particles may or may not be chemically bonded to the precursor. Further, the surface of the precursor of the porous crosslinked polymer fine particles may have a crosslinked polymer having a high crosslink density.

In the method of the present invention, the precursor of the porous crosslinked polymer fine particles obtained in the above step is then subjected to a step of extracting a solvent-soluble substance (Step B). As a result, uniform particle size particles can be obtained, which are made of crosslinked polymer particles imparted with porosity. These uniformly sized fine particles generally have excellent mechanical strength.

Extraction of solvent-soluble substances can be performed, for example, by the following method.

That is, water as a dispersion medium in the aqueous dispersion containing the precursor of porous crosslinked polymer fine particles obtained in the above step A is gradually replaced with a less polar medium, and the non-crosslinked monomer used is Finally, the polymer or its polymer is replaced with a medium having a similar SP value (solubility parameter) to that of the pore control agent, and washing is repeated with this medium to make the precursor of the porous crosslinked polymer fine particles soluble in the solvent. Extract the substance.

As the substitution medium, it is generally desirable to use a volatile low boiling point solvent, since it is ultimately desired to remove it from the fine particles. Typical examples include alcohols such as methanol and ethanol, ketones such as acetone, acetonide salts thereof, chloroform, tetrahydrofuran, benzene, toluene, xylene, and ethylbenzene. The displacement medium may be a mixed medium with water or a mixed medium using two or more types of solvents.

In some cases, it is efficient to carry out the extraction process by dispersing the precursor of the porous crosslinked polymer particles in a replacement medium. In that case, it is also possible to apply a dispersion method using ultrasonic waves, for example.

Note that the substitution medium remaining in the porous crosslinked polymer fine particles after the extraction treatment can be easily removed by, for example, a vacuum drying method, a spray dryer, or the like.

As described above, the particle size is 2 to 30 um%, preferably 2 to 20 μIl+, the standard deviation of particle size distribution is 1 μm or less, preferably 0.5μ10 or less, excellent solvent resistance, and porous uniform particle size. Fine particles are obtained. These uniform particle size particles generally contain a crosslinked polymer with a high crosslinking density inside a crosslinked polymer with a low crosslinking density, and have a huge network porosity.
It consists of crosslinked polymer microparticles with a specific structure of 30n? /g or more, preferably 50-1000+&/g
, more preferably 100 to 500 jt/g, and has excellent sphericity and mechanical strength.

In addition, it is also possible to use an ion exchange resin or the like as the uniform particle size fine particles having a functional group such as an ion exchange group.

Effects of the Invention According to the present invention, non-crosslinked polymer fine particles with excellent particle size uniformity are first made into crosslinked polymer fine particles having a crosslinked polymer with a low crosslink density, and then these are made into crosslinked polymer fine particles containing a crosslinkable monomer. The method uses a method in which a precursor of porous crosslinked polymer fine particles is obtained by treating it with a monomer mixture with a high concentration and a pore control agent, and then solvent-soluble substances are removed from this precursor, resulting in uniform particle size. It is possible to obtain uniformly sized fine particles with excellent solvent resistance and porosity in a high yield without classifying them (in a state that can be used for practical purposes). It has a large specific surface precision.

Examples Reference Examples Sodium lauryl sulfate 0.6 parts (parts by weight, the same applies hereinafter)
After dispersing 30 parts of styrene in 65 parts of ion-exchanged water, the temperature was raised to 70°C under a nitrogen stream while stirring, and then 5 parts of ion-exchanged water with 0.03 parts of potassium persulfate dissolved therein. The mixture was heated to 70° C. for 8 hours to obtain an aqueous dispersion of a non-crosslinked polymer as initial seed particles. The particle size of this non-crosslinked polymer was 0.045 μm, and the standard deviation of the particle size distribution was 0.011 μI or less.

Next, 10 parts of the aqueous dispersion of the obtained initial seed particles and 65 parts of ion-exchanged water were mixed, heated to 70°C, 27 parts of styrene was added and stirred for 1 hour, and then 0.1 parts of potassium persulfate was added. Add 5 parts of ion-exchanged water and heat to 70°C.
The particle size was maintained at 2 pm for 8 hours.

An aqueous dispersion of secondary seed particles with a standard deviation of particle size distribution of 0.014 μl was obtained. Further, according to the above, the tertiary seed particles are replaced with the secondary seed particles, and the tertiary seed particles are replaced with 4 times the tertiary seed particles.
Secondary seed particles were sequentially prepared from 4th seed particles to 5th seed particles with the compositions shown in the table.

Example 1 The quaternary seed particles obtained in Reference Example were used as non-crosslinked polymer particles (Atsuno particles), and 100 parts of ion-exchanged water and 10 parts of polyvinyl alcohol with a saponification degree of 88% were added to 10 parts of water dispersion a as a preparation liquid. After adding 5.0 parts of % aqueous solution and stirring uniformly, 99.85% by weight of styrene and 0 parts of divinylbenzene were added.
．． 0.2 parts of benzoyl peroxide was dissolved in 16 parts of a 15% by weight monomer mixture, and 120 parts of ion-exchanged water and 0.015 parts of sodium lauryl sulfate were mixed therewith to form an emulsion under ultrasonication. was added and polymerized for 8 hours at 80° C. under a nitrogen stream while stirring to obtain an aqueous dispersion containing crosslinked polymer fine particles. The particle size of this crosslinked polymer fine particle is 1.217 parts m, and the standard deviation of the particle size distribution is 0.060 parts m.
The degree of swelling with respect to styrene was 11.

Next, 100 parts of ion-exchanged water and 5 parts of the above-mentioned polyvinyl alcohol aqueous solution were added to 12 parts of the obtained aqueous dispersion of crosslinked polymer fine particles, and after uniformly stirring, styrene 6
Dissolve 0.8 part of benzoyl peroxide in a mixture of 16.8 parts of a monomer mixture of 5% by weight and 35% by weight of divinylbenzene and 14 parts of 11-hexyl alcohol, and add 130 parts of ion-exchanged water and sodium lauryl sulfate to this solution. A mixture of 0.012 parts and an emulsion was added under ultrasonication, and copolymerization was carried out at 55°C for 2 hours under a nitrogen stream while stirring, and then heated to 80°C for 6 hours to form a porous An aqueous dispersion containing a precursor of crosslinked polymer fine particles was obtained. The particle size of this precursor is 3.1
The standard deviation of the 1 μm 1 particle size distribution was 0.15 tt+n.

Next, the dispersion medium in this aqueous dispersion was changed from water to methanol, ethanol, acetone, acetone/toluene (1/1
) and toluene to prepare a toluene dispersion, which was then heated at its boiling point temperature for 40 hours. Thereafter, fine particles were separated from the toluene dispersion and further washed with toluene, and then the dispersion medium was replaced in the reverse order to prepare an aqueous dispersion.

The extracted porous crosslinked polymer fine particles were separated from the obtained aqueous dispersion and dried under reduced pressure.

The uniform particle size fine particles as the porous crosslinked polymer fine particles obtained have a particle size of 3.5 mm. The standard deviation of the llums particle size distribution was 0.15 μm, which was the same as that of the precursor described above. In addition, the weight loss of the fine particles after the extraction treatment, that is, the weight loss of the uniform diameter fine particles as the porous crosslinked polymer fine particles obtained by the extraction treatment with respect to the precursor of the porous crosslinked polymer fine particles is 40%. %Met.

Furthermore, B, E.

The specific surface area determined by the T method (nitrogen gas adsorption) is 210
．． It was 4nY/g. In addition, as a result of observation using a scanning electron microscope, it was found that in addition to being porous, it was also excellent in perfect spherical shape 11.

Example 2 The 5th seed particles obtained in Reference Example were used as non-crosslinked polymer fine particles, and 10 parts of an aqueous dispersion as a preparation liquid, 100 parts of ion-exchanged water, and the above-mentioned polyvinyl alcohol water-soluble i5 were added.
After stirring uniformly, 0.2 parts of benzoyl peroxide was dissolved in 16 parts of a monomer mixture of 99.85% by weight of styrene and 0.15% by weight of divinylbenzene, and 120 parts of ion-exchanged water was dissolved therein. , sodium lauryl sulfate o, o
The ts part was mixed and an emulsion was added under ultrasonic treatment, and the mixture was polymerized at 80°C for 8 hours under a nitrogen stream while stirring.
An aqueous dispersion containing crosslinked polymer fine particles was obtained. The particle size of this crosslinked polymer fine particle is 2.41 parts m, the standard deviation of the particle size distribution is 0.12 parts m, and the degree of swelling with respect to styrene is 1
It was 2.

Next, 50 parts of ion-exchanged water and 3 parts of the above-mentioned polyvinyl alcohol aqueous solution were added to 5 parts of the obtained aqueous dispersion of crosslinked polymer fine particles and stirred uniformly. % monomer mixture 8.
Dissolve 0.4 part of benzoyl peroxide in a mixture of 4 parts of n-hexyl alcohol and 7 parts of n-hexyl alcohol, and add 65 parts of ion-exchanged water to this solution.
1 part and 0.006 part of sodium lauryl sulfate were mixed together to make an emulsion under ultrasonication, and the mixture was copolymerized at 55°C for 2 hours under a nitrogen stream with stirring, and then heated to 80°C for 6 hours. An aqueous dispersion containing a precursor of porous crosslinked polymer fine particles was obtained. The particle size of this precursor was 6.71 μm, and the standard deviation of the particle size distribution was 0.28 μm.

Next, extraction treatment and drying treatment were carried out in the same manner as in Example 1 to obtain porous crosslinked polymer fine particles.

The obtained porous crosslinked polymer fine particles having a uniform particle size had a particle size of 6.70 μm and a standard deviation of particle size distribution of 0.28 μIII, which was almost the same as that of the precursor described above. . Furthermore, the weight reduction of the fine particles after the extraction treatment was 38%.

Furthermore, the specific surface area determined by the B, E, T method (nitrogen gas adsorption) is 106. It was LJ/g. In addition, as a result of observation using a scanning electron microscope (IMM), it was found that in addition to being porous, it was also excellent in sphericity.

Example 3 50 parts of ion-exchanged water and 3 parts of the above polyvinyl alcohol aqueous solution were added to 5 parts of the aqueous dispersion of the same crosslinked polymer fine particles as in Example 2 and stirred uniformly, followed by 65% by weight of styrene and divinylbenzene. 35% by weight monomer mixture8.
4 parts, 70% by weight of n-hexyl alcohol, and 3 parts of toluene.
Dissolve 0.4 parts of benzoyl peroxide in a mixture with 10 parts of a 0% by weight precipitant/swelling agent mixture, mix 65 parts of ion-exchanged water and 0.006 parts of sodium lauryl sulfate, and subject to ultrasonication. The emulsion was added and copolymerized for 2 hours at 55°C under a nitrogen stream with stirring, then heated to 80°C for 6 hours to form an aqueous dispersion containing a precursor of porous crosslinked polymer fine particles. I got the liquid. The particle size of this precursor is 6.75μ
The standard deviation of the m1 particle size distribution was 0.28 part m.

Next, extraction treatment and drying treatment were carried out in the same manner as in Example 17 to obtain porous crosslinked polymer fine particles.

The obtained porous crosslinked polymer fine particles having a uniform particle size had a particle size of 6.75 μm and a standard deviation of 1 particle size distribution of 0.28 parts m, which was the same as that of the precursor described above. Ta. Further, the weight loss of the fine particles after the extraction treatment was lI 1%. Furthermore, the specific surface area determined by the B, E, T method (nitrogen gas adsorption) is 156.2
It was J/g. Furthermore, as a result of observation using a scanning electron microscope, it was found that in addition to being porous, it also had excellent sphericity.

Example 4 The 5th seed particles obtained in Reference Example were used as non-crosslinked polymer fine particles, and 100 parts of ion-exchanged water and the above polyvinyl alcohol aqueous solution 5 were added to 10 parts of an aqueous dispersion as a preparation liquid.
99.85% by weight of styrene and 0.15% by weight of divinylbenzene! Dissolve 0.2 parts of benzoyl peroxide in 16 parts of the 4L polymer mixture, mix 120 parts of ion-exchanged water and 0.015 parts of sodium chloride sulfate, and add the resulting emulsion under sonication. The mixture was polymerized for 8 hours at 80° C. under a nitrogen stream with stirring to obtain an aqueous dispersion containing crosslinked polymer fine particles.

The particle size of this crosslinked polymer fine particle was 2.41 μm, the standard deviation of the particle size distribution was 0.12 μm, and the degree of swelling with respect to styrene was 12.

Next, 50 parts of ion-exchanged water and 3 parts of the above-mentioned polyvinyl alcohol aqueous solution were added to 5 parts of the aqueous dispersion of crosslinked polymer fine particles (q), and after uniformly stirring, styrene 65
% by weight, monomer mixture of 35% by weight of divinylbenzene 8
．． 0 parts of benzoyl peroxide in a mixture of 4 parts and 1 part of toluene.
．． 4 parts of the solution was dissolved, 65 parts of ion-exchanged water and 0.006 parts of sodium lauryl sulfate were mixed thereto, an emulsion was added under ultrasonication, and the mixture was heated for 55 minutes under a nitrogen stream while stirring.
The mixture was copolymerized at 80° C. for 2 hours and then heated to 80° C. for 6 hours to obtain an aqueous dispersion containing a precursor of porous crosslinked polymer particles.

The particle size of this precursor was 6.80 νIn, and the standard deviation of the particle size distribution was 0.33 μm1.

Next, extraction treatment and drying treatment were carried out in the same manner as in Example 1 to obtain porous crosslinked polymer fine particles.

The obtained porous crosslinked polymer fine particles with a uniform particle size have a particle size of 6.8 parts m% and a standard deviation of the particle size distribution of 0.33 μm, which is almost different from that of the precursor described above. There was no. Furthermore, the weight reduction of the fine particles after the extraction treatment was 38%.

Furthermore, the specific surface area determined by the B,E,'r method (nitrogen gas adsorption) was 305.2r&/g. Furthermore, as a result of observation using a scanning electron microscope, it was found that in addition to being porous, it also had excellent sphericity.

Claims (1)

[Claims] 1. (A) Water and a non-crosslinking monomer are added to an aqueous dispersion of seed particles and polymerized, and the resulting particles are used as the next seed particle to further grow the diameter. The operation was repeated two or more times using a non-crosslinked polymer obtained by treating a non-crosslinkable monomer in an aqueous medium as initial seed particles, and the particle size was 0.5 to 2.
A non-crosslinking monomer of 99 to 99 mm is added to an aqueous dispersion of non-crosslinked polymer fine particles having a standard deviation of particle size distribution of 0.1 μm or less in μm.
A monomer mixture consisting of 95% by weight and 1 to 0.05% by weight of a crosslinkable monomer is added and polymerized, and 50 to 90% of a non-crosslinkable monomer is added to the resulting crosslinked polymer fine particles. A step of absorbing a monomer mixture consisting of 50 to 10% by weight of a crosslinkable monomer and a pore control agent, and copolymerizing the same in an aqueous medium to obtain a precursor of porous crosslinked polymer fine particles. (B) consists of a step of extracting a solvent-soluble substance from the precursor of porous crosslinked polymer fine particles obtained in the above step.The particle size is 2 to 30 μm and the standard deviation of the particle size distribution is 1.
A method for producing fine particles having a uniform particle size of .mu.m or less, solvent resistance, and porosity. 2. The method according to claim 1, which uses an emulsifier. 3. The method according to claim 1, wherein the pore regulating agent is insoluble in water and soluble in the monomer mixture or its constituent monomers. 4. A monomer mixture containing 50 to 10% by weight of a crosslinkable monomer per 100 parts by weight of crosslinked polymer fine particles.
2. The method according to claim 1, wherein the pore-adjusting agent is used in an amount of 100 to 6,000 parts by weight. 5. The method according to claim 1, wherein the monomer mixture containing 50 to 10% by weight of the crosslinkable monomer contains a polymerization initiator. 6. The method according to claim 1, wherein a monomer mixture containing 50 to 10% by weight of a crosslinkable monomer and a pore regulator are added in an emulsified state to an aqueous dispersion of crosslinked polymer fine particles.