JPS62227901A - Solvent-resistant porous fine particle of uniform particle diameter and its production - Google Patents

Abstract

PURPOSE:To produce the titled porous 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:An aqueous dispersion of uncrosslinked fine polymer particles of a particle diameter of 0.5-2mum and a standard deviation of a particle distribution <=0.1mum is obtained by repeating the polymerization of initial seed particles comprising an uncrosslinked polymer obtained by polymerizing a noncrosslinking monomer in an aqueous medium at least twice. To this aqueous dispersion a monomer mixture comprising 99-99.95wt% noncrosslinking monomer and 1-0.05wt% crosslinking monomer is added and polymerized to obtain a crosslinkable fine polymer particles. 100-3,000pts.wt. monomer mixture comprising 50-90wt% noncrosslinkable monomer and 50-10wt% crosslinkable monomer is absorbed by 100pts.wt. above-produced fine particles and copolymerized in an aqueous medium to obtain a precursor of porous fine crosslinked 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 Field of Industrial Application The present invention is a porous cross-linked polymer fine particle composed of a cross-linked polymer with a low cross-link density and a cross-linked polymer with a high cross-link density, and has a particle size of 2 to 30 μm. The present invention relates to solvent-resistant, porous, uniformly sized fine particles having a standard deviation of particle size distribution of 1 μm1 or less, and a method for producing the same.

Conventional Technology Polymer fine particles used as opacifying agents, matting agents, organic pigments or fillers, thickness and gap adjusting materials, carriers for chromatography, etc. are strongly required to have uniform particle diameters. In addition, 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 it does not dissolve or swell in the solvent.Furthermore, Porous properties are also desired in applications where a large surface pore is advantageous, such as when used as a chromatography carrier.

Conventionally, solvent-resistant fine particles with a uniform particle size have been produced by polymerizing seed particles of crosslinked polymer particles, absorbing a non-crosslinkable monomer or a mixture of crosslinkable monomers into the seed particles, and then polymerizing them. It was known (Japanese Unexamined Patent Publication No. 59-18705)
British Patent No. 728508, British Patent No. 111
No. 6800).

On the other hand, as porous particles with a uniform particle size, hydrophilic vinyl monomers and acrylic acid, etc., or phenyl group-containing particles are prepared by combining hydrophilic vinyl monomers and acrylic acid, etc., in the presence of an organic solvent that dissolves the monomers used but does not dissolve the reaction products. There are known methods in which a hydrophobic monomer and a hydrophilic monomer are polymerized in aqueous suspension and then the organic solvent is removed.
-83260).

Problems to be Solved by the Invention However, even when simply obtaining the above-mentioned solvent-resistant particles, there is a problem in that the particles obtained have poor uniformity in particle size.

Further, even when using an aqueous suspension polymerization method to obtain the porous 11, there is a problem that the particle size distribution of the obtained 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 3 hm.

Therefore, the standard deviation of the particle size distribution is 1 when the particle size is 2 to 30μ...
νm or less, solvent-resistant, and porous uniform particle size particles have not been known so far.

Means for Solving the Problems The present inventors have overcome the above problems, and have
As a result of intensive research to develop fine particles with a uniform particle size that is solvent resistant and porous, with a standard deviation of particle size distribution of 1 μI or less in p u The crosslinked polymer fine particles are first treated with a monomer mixture containing a low concentration of crosslinking monomer 11 to form crosslinked polymer fine particles, and then these are treated with a monomer mixture containing a high crosslinking monomer concentration. The purpose is achieved by copolymerizing the mixture while absorbing it to obtain a precursor of porous crosslinked polymer particles, and removing solvent-soluble substances from the obtained precursor to obtain porous crosslinked polymer particles. They discovered scales and came up with the present invention.

That is, the present invention uses a crosslinked polymer with a low crosslinking density obtained by copolymerizing a monomer mixture containing 0.05 to 1% by weight of a crosslinkable monomer, and a crosslinked polymer containing 10 to 50% by weight of a crosslinkable monomer. It consists of porous crosslinked polymer fine particles consisting of a crosslinked polymer with a high crosslinking density obtained by copolymerizing a monomer mixture containing % by weight, and the particle size is 2 to 3 h... and the standard deviation of the particle size distribution is 1 μm or less and
Solvent resistant and porous uniform particle size particles and (A) water and a non-crosslinked 11 monomer are added to an aqueous dispersion of seed particles and polymerized, and the resulting particles are used as the next seed particle. The operation of further growing the diameter 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 0.5. 99 to 99.95% by weight of non-crosslinkable monomer and 1 to 0.05% by weight of crosslinkable monomer to an aqueous dispersion of non-crosslinked polymer fine particles having a diameter of 2 um and a standard deviation of particle size distribution of 0.1 μfO or less. A monomer mixture consisting of 50 to 90% by weight of non-crosslinkable monomers and 50 to 10% by weight of crosslinkable monomers is added in the resulting crosslinked polymer fine particles. absorb the monomer mixture,
A step of copolymerizing this in an aqueous medium to obtain a precursor of porous crosslinked polymer fine particles, (B) 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 um, and the standard deviation of the particle size distribution is 1.
The present invention provides a method for producing fine particles having a uniform particle size of .mu.m or less, which is solvent resistant and porous.

Hereinafter, an example of the uniform particle diameter fine particles of the present invention will be explained based on its manufacturing method.

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. Absorbs a monomer mixture with a high concentration of monomers,
This is copolymerized to obtain a precursor of porous crosslinked polymer fine particles (Step A).

At that time, the non-crosslinked polymer fine particles were obtained by repeating seed polymerization using a non-crosslinkable monomer two or more times, and had a particle size of 0.
．． 5 to 2 μm, standard deviation of particle size distribution is 0, lun or less,
Preferably, one with a thickness of 0.05 um or less is used. That is, an aqueous dispersion of seed particles is mixed with water, a non-crosslinking monomer, and, if necessary, an amount of emulsifier (
It is preferable that the surface tension is 55 dynes/cm or more. ) and polymerization treatment by adding a polymerization initiator,
The obtained particles are used as the next seed particle and the operation of growing the diameter 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 polymer in an emulsion obtained by processing a non-crosslinkable monomer by a conventional emulsion polymerization method or the like is used.

By using non-crosslinked polymer fine particles that satisfy these conditions, the particle size, standard deviation of particle size distribution, and porosity in the final target product can be achieved.

The above-mentioned non-crosslinked polymer fine particles contain a crosslinkable monomer c
It is subjected to treatment with a monomer mixture having a low degree of a. That is, the non-crosslinked polymer fine particles contain 99 to 99.95% by weight of the non-crosslinkable monomer in the aqueous dispersion. 6, preferably 99.5~
99.9% by weight and 1 to 0.05% by weight of crosslinkable monomer? 6,
A monomer mixture preferably consisting of 0.5 to 0.1% by weight is added, and this is absorbed into non-crosslinked polymer fine particles and copolymerized to obtain crosslinked polymer fine particles. As a result, a monomer mixture with a high concentration of crosslinkable monomers used later or a monomer that is swollen with its constituent monomers is obtained, and a crosslinked polymer with a low crosslink density is formed in the final target product. The final target product can be made into fine particles with a uniform particle size and generally excellent sphericity. The swelling degree (volume ratio of particles before and after swelling) of the crosslinked polymer fine particles obtained using the monomer mixture at the above mixing ratio is usually 8 to 1.
It is 00. 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 to obtain the above-mentioned crosslinked tA-based polymer fine particles is too small, a product with an excessive swelling degree will be obtained. The purpose of the present invention is difficult to achieve because the solvent resistance of uniform particle size particles is insufficient.

On the other hand, if the content of the crosslinking monomer is too large, particles with too small a degree of swelling (excessive crosslinking density) will be obtained, and the monomer mixture used later will not be able to sufficiently diffuse into the particles. The purpose of the method of the present invention may not be fully achieved because the polymerization in the particles becomes insufficient and new particles are likely to be generated which causes variation in particle size.

The amount of the monomer mixture used in the treatment for obtaining crosslinked polymer fine particles from the non-crosslinked polymer fine particles described above is not limited, but is preferably 2000 parts by weight or less per 100 parts by weight of non-crosslinked polymer fine particles. It is preferably 1000 parts by weight or less. If the amount used is excessive, the resulting crosslinked polymer II particles may have a wide particle size distribution, and the purpose of the method 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-conducting polymer fine particles modified with a cross-linked polymer having a low cross-link density), the cross-linked polymer fine particles are composed of a monomer having a high concentration of cross-linkable monomers. It is used as a reaction base for mixtures.In other words, a monomer mixture containing a high concentration of crosslinkable monomers is absorbed into crosslinked polymer fine particles, and then this is absorbed in the presence of a polymerization initiator.
It is subjected to a copolymerization process. As a result, at least some of the crosslinked polymer fine particles having a crosslinked polymer with a low crosslinking density are filled with a monomer mixture containing a high concentration of crosslinkable monomer (high crosslinked polymer with a density of 19). A precursor of porous crosslinked polymer fine particles having an expanded particle size is obtained.

The process of absorbing the monomer mixture into crosslinked polymer fine particles is a method in which the monomer mixture is added to a dispersion of crosslinked polymer fine particles, especially an aqueous dispersion as an emulsion polymerization liquid, and the mixture is stirred. is common. 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. 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 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 amount of the monomer mixture used in the treatment to obtain the precursor of the porous crosslinked polymer fine particles is 1% of the crosslinked polymer fine particles.
100 to 3000 parts by weight per 00 parts by weight is suitable. If the amount used is less than 100 parts by weight, the solvent resistance of the resulting uniform particle size particles will be insufficient, and if it exceeds 3,000 parts by weight, polymerization outside the crosslinked polymer particles will tend to proceed, which is undesirable. .

The mixing ratio of the non-crosslinkable monomer and the crosslinkable monomer in the monomer mixture used in the treatment is 50 to 90% by weight of the non-crosslinkable monomer and 50 to 10% by weight of the crosslinkable monomer.
is appropriate. When the mixing ratio of the crosslinkable monomer exceeds 50% by weight, the crosslinking density of the resulting crosslinked polymer becomes excessive,
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.

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 desirable to use the oil-soluble polymerization initiator dissolved in the monomer mixture in an amount of 0.1 to 3% 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.

As a non-crosslinkable monomer for obtaining non-crosslinked polymer fine particles in the method of the present invention, or as a monomer in a monomer mixture for obtaining a precursor of crosslinked polymer fine particles or porous crosslinked polymer fine particles. It is preferable to use those which themselves or their polymers are poorly soluble or insoluble in water. If the material is easily soluble in water, polymerization will proceed in water, making it difficult for the particle size of seed particles to grow, making it easier to form new particles, or increasing the crosslinked polymer content in non-crosslinked polymer fine particles. This is not preferable because it may be difficult to absorb into molecular fine particles.

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

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

The number of non-crosslinkable monomers and crosslinkable monomers may be one, or two or more.

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. It is preferable to use divinylbenzene, which has low solubility, as the crosslinking monomer. Incidentally, styrene monomers have the advantage of not agglomerating during copolymerization (the process can proceed stably).

By performing the copolymerization treatment as described above, the particle size of the crosslinked polymer fine particles having a crosslinked polymer having a high crosslinking density inside the crosslinked polymer fine particles having a crosslinked polymer having a low crosslinking density becomes 2 to 3.
0 νm1 is preferably 2 to 20 νm, the standard deviation of the particle size distribution is 14 or less, preferably 0.5 μm or less, and a precursor of porous crosslinked polymer fine particles having generally 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.

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 is replaced with a medium that has a similar SP value (solubility parameter) to the polymer, and washing is repeated with this medium to extract and remove the solvent-soluble substances in the precursor of the porous crosslinked polymer fine particles. do.

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, acetonitrile, chloroform, tetrahydrofuran, benzene, toluene, xylene, and ethylbenzene. The displacement medium may be a hot medium with water or a hot medium using two or more types of solvents.

The extraction process may be carried out dynamically by dispersing the precursor of the porous crosslinked polymer fine particles in a displacement medium. In that case, it is also possible to apply a dispersion method using ultrasonic waves, for example.

Incidentally, the substitution medium remaining in the porous crosslinked polymer fine particles after the extraction treatment can be easily removed by, for example, a method such as a spray dryer.

As described above, it is made of porous crosslinked polymer fine particles that generally have a structure containing a crosslinked polymer with a high crosslinking density inside a crosslinked polymer with a low crosslinking density, and has excellent solvent resistance and a particle size of 2.
~30 u+n, preferably 2-20 μm, with a standard deviation of particle size distribution of 1 μm or less, preferably 0,5 p+
Fine particles with a uniform particle size of n or less can be obtained. These uniform particle size particles generally have excellent sphericity and have a particle size of 50+J/g.
In particular, it has a specific surface area of 30 nf/g or less.

In addition, the uniform particle diameter fine particles of the present invention can be obtained by, for example, a method in which a precursor of porous crosslinked polymer fine particles is obtained by removing it in a subsequent extraction step and using a pore control agent together, or by further replacing it with non-crosslinked polymer fine particles. Polymer fine particles with low crosslinking density and excellent particle size uniformity prepared by direct seed polymerization method etc. are used as particles to obtain a precursor of porous crosslinked polymer fine particles, and the above-mentioned pore control agent is used. It may be possible to increase the pore diameter or specific surface area or create a giant network-like porous structure by other methods.

Further, the uniform particle diameter fine particles of the present invention can be made into an ion exchange resin or the like by having a functional group such as an ion exchange group.

Effects of the Invention The uniform particle diameter fine particles of the present invention are composed of porous crosslinked polymer fine particles consisting of a crosslinked polymer with a low crosslinking density and a crosslinked polymer with a high crosslinking density, so they have excellent solvent resistance. It has a large specific surface area. It also has excellent particle size uniformity.

On the other hand, according to the method of the present invention, it is possible to obtain the above-mentioned uniform-sized fine particles in a high yield in a state where they can be used for practical purposes without being subjected to classification treatment.

Examples Reference Examples Sodium lauryl sulfate 0.6 parts (parts by weight, the same applies hereinafter)
After dispersing 28 parts of styrene in 70 parts of ion-exchanged water, the mixture was heated at 70°C under a nitrogen stream while stirring.
Then, 5 parts of ion-exchanged water in which 0.03 part of potassium persulfate was dissolved was added, and the mixture was kept at 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 0.04 μIn, and the standard deviation of the particle size distribution was 0.01 part m.

Next, 10 parts of the aqueous dispersion of the obtained initial seed particles and 65 parts of ion-exchanged water were mixed and heated to 708C, then 28 parts of styrene was added and stirred for 1 hour, followed by 0.03 part of potassium persulfate. Add 5 parts of ion-exchanged water dissolved in 7
Maintained at 0°C for 8 hours, particle size 0.138μIn.

An aqueous dispersion of secondary seed particles with a standard deviation of particle size distribution of 0.012 part m 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, and from 5th seed particles to 6th 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 fine particles, and the prepared solution was a water dispersion overnight of 10 parts, 120 parts of ion-exchanged water, and 100 parts by weight of polyvinyl alcohol with a degree of saponification of 88%. Part 6 Added 10 parts of aqueous solution and stirred homogeneously, then dissolved 0.2 parts of hendiyl peroxide in 12 parts of a monomer mixture of 99.7 parts by weight of styrene, 6 parts by weight of divinylbenzene, and 0.3 parts by weight of divinylbenzene. 150 parts of ion exchange water,
Add 0.015 parts of sodium lauryl sulfate to make an emulsion under ultrasonic treatment, and polymerize at 80°C for 9 hours under a nitrogen stream while stirring to obtain an aqueous dispersion containing crosslinked polymer fine particles. Obtained. The particle size of this crosslinked polymer fine particle is 1.12111, the standard deviation of the particle size distribution is 0.06 part m,
The degree of swelling with respect to styrene was 11.

Next, water dispersion of the obtained crosslinked polymer fine particles)
After adding 100 parts of ion-exchanged water and 20 parts of the above polyvinyl alcohol aqueous IrJt to the mixture and stirring uniformly,
0.4 parts of benzoyl peroxide is dissolved in 30 parts of a monomer mixture of 70% by weight of styrene and 30% by weight of divinylbenzene, and 200 parts of ion-exchanged water and 0.018 parts of sodium lauryl sulfate are mixed therein and treated with ultrasound. Add the emulsified liquid to the bottom, and stir at 60°C under a nitrogen stream for 2 hours.
Subsequently, the temperature was raised to 80° C. and a copolymerization treatment was performed for 6 hours to obtain an aqueous dispersion containing a precursor of porous crosslinked polymer fine particles. The particle size of this precursor was 2.81'lll%, and the standard deviation of the particle size distribution was 0.12+lll1.

Next, methanol, ethanol, acetone, acetone/toluene (1/
1) A mixed solvent and toluene were substituted in order to obtain a toluene dispersion, and the mixture was 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 porous crosslinked polymer fine particles after the extraction treatment were separated from the obtained aqueous dispersion, and treated and dried using a spray dryer.

The obtained porous crosslinked polymer fine particles with a uniform particle size have a particle size of 2.8μ11 and a standard deviation of particle size distribution of 0.
, 12+JI11, which was the same as in the case of the precursor described above. In addition, the weight loss of fine particles after extraction treatment, that is, the weight loss of uniform particle size fine particles as porous crosslinked polymer fine particles obtained by extraction treatment with respect to the precursor of porous crosslinked polymer fine particles, is 2 It was .2%. Furthermore, B, E.

The specific surface area determined by the T method (nitrogen residue adsorption) is 3,
211i/g, and was found to be more porous than this. Furthermore, as a result of observation using a scanning electron microscope, it was also found that the sphericity was excellent.

Example 2 The 5th seed particles obtained in Reference Example were used as non-crosslinked polymer fine particles, and water dispersion 1 ((120 parts of ion-exchanged water and 10 parts of the above polyvinyl alcohol aqueous solution were added to 10 parts of the above-mentioned polyvinyl alcohol aqueous solution to 10 parts) After stirring uniformly, step 1299.
0.15 parts of benzoyl peroxide was dissolved in 9 parts of a monomer mixture containing 5% by weight of divinylbenzene and 0.25% by weight of divinylbenzene. The emulsion was added to the emulsion under sonication, and polymerization was carried out at 80° C. under a nitrogen stream for 9 hours while stirring to obtain an aqueous dispersion containing crosslinked polymer fine particles. The crosslinked polymer fine particles had a particle size of 2.18 .mu.m, a standard deviation of particle size distribution of 0.09 .mu.m, and a swelling degree of 10 for 1 styrene.

Next, 60 parts of ion-exchanged water and 10 parts of the above-mentioned polyvinyl alcohol aqueous solution were added to 24 parts of the obtained aqueous dispersion of crosslinked polymer fine particles, and after uniformly stirring, 7 parts of styrene
0.2 parts of benzoyl peroxide is dissolved in 18 parts of a monomer mixture containing 0% by weight of divinylbenzene and 30% by weight of divinylbenzene, and 100 parts of ion-exchanged water and 0.0 parts of sodium lauryl sulfate are dissolved therein.
0.6 parts were mixed and treated with ultrasonic waves to form an emulsion, which was then copolymerized at 60°C for 2 hours under a nitrogen stream while stirring, and then heated to 80°C for 6 hours to form a porous crosslinking agent. An aqueous dispersion containing a precursor of polymer fine particles was obtained. The particle size of this precursor is 5.64 μm, and the standard deviation of the particle size distribution is 0. lhm
Met.

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 have a particle size of 5.64 parts ms and a standard deviation of particle size distribution of 0.19 parts m, which is different from that of the precursor described above. There was no. Furthermore, the weight loss of the fine particles after the extraction treatment was 2.4%. Furthermore, the specific surface area determined by the B, E, T method (nitrogen gas adsorption) is 6.5 J/
It was found that the material was porous. Furthermore, as a result of observation using a scanning electron microscope, it was also found that the sphericity was excellent.

Example 3 The sixth seed particles obtained in Reference Example were used as non-crosslinked polymer fine particles, and 120 parts of ion-exchanged water and the above polyvinyl alcohol aqueous solution 1 were added to 10 parts of an aqueous dispersion as a preparation liquid.
After adding 0 parts and stirring uniformly, add styrene 99.7S.
0.615 parts of benzoyl peroxide was dissolved in 10 parts of a monomer mixture of ffi amount% and divinylbenzene 0.25 ffi amount%, and 140 parts of ion-exchanged water and 0.01 part of sodium lauryl sulfate were mixed therewith and subjected to ultrasonic treatment. An emulsion was added to the mixture, and polymerization was carried out at 80° C. under a nitrogen stream for 9 hours without stirring to obtain an aqueous dispersion containing crosslinked polymer fine particles. The particle size of this crosslinked polymer fine particle was 4.39 μm, the standard deviation of the particle size distribution was 0.10 ν+n, and the degree of swelling with respect to styrene was 10.5.

Next, 100 parts of ion-exchanged water and the above-mentioned part of polyvinyl alcohol aqueous FtlB were added to 43 parts of the obtained aqueous dispersion of crosslinked polymer particles, and after uniformly stirring, 70% by weight of styrene and 30% by weight of divinylbenzene were added. Dissolve 0.4 part of benzoyl peroxide in 32 parts of a monomer mixture of
．． 012 parts were mixed and an emulsion was added under ultrasonic treatment, and the mixture was copolymerized at 60°C for 2 hours under a nitrogen stream while stirring, and then the temperature was raised to 80'C for 6 hours to form a porous crosslinker. An aqueous dispersion containing a precursor of polymer fine particles was obtained. The particle size of this precursor is 11.3 μm, and the standard deviation of the particle size distribution is 0.30 μm.
There was no hat.

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 had a particle size of 11.3 μm and a standard deviation of particle size distribution of 0.30 μm, which was the same as that of the precursor described above. . Furthermore, the weight loss of the fine particles after the extraction treatment was 2.2%. Furthermore, the specific surface area determined by the B, E, T method (nitrogen gas adsorption) is 13.1+
J/g and was found to be porous. In addition,
As a result of observation using a scanning electron microscope, it was also found that it has excellent sphericity.

Comparative Reference Example 700 parts of ion-exchanged water and 4 parts of a 0.6% aqueous solution of polyvinyl alcohol with a degree of saponification of 88% were added and stirred uniformly. Add 2 parts of benzoyl peroxide dissolved in 80 parts of the monomer mixture, and mix with a homogenizer to 1 part.
After stirring for 1 hour at 0,000 rpm, the
Polymerization treatment was carried out at °C for 9 hours to obtain polymer fine particles with a low crosslinking density.

(The particle size of the slicked polymer particles ranged from 2 to 15 μm. Furthermore, the particles were subjected to wet classification to have an average particle size of 9.4 rtfl, which is the standard particle size distribution in China. The deviation was more than 2 μm.

The degree of swelling of the polymer fine particles with respect to styrene is 14.
Met.

Comparative Example 1 Ion-exchanged water was added to 10 parts (solid content 30% by weight) of an aqueous dispersion of crosslinked polymer fine particles having a particle size of 5 parts m1, a standard deviation of particle size distribution of 1.0 μm, and a degree of swelling with respect to styrene of 10. 10
After adding 0 parts and 15 parts of a 10% by weight aqueous solution of polyvinyl alcohol mentioned above and stirring uniformly, 70% by weight of styrene and 30% by weight of divinylbenzene were added! , 0.5 parts of hendiyl peroxide was dissolved in 45 parts of the monomer mixture of
．． 018 parts were mixed together to make an emulsion under ultrasonication, and the mixture was copolymerized at 60°C for 2 hours under a nitrogen stream while stirring, and then heated to 80°C for 6 hours to form a porous crosslinked polymer. An aqueous dispersion containing a precursor of coalesced fine particles was obtained.

However, although the particle size of this precursor was 12.2 parts m, the standard deviation of its particle size distribution was as high as 2.1 μm.

Claims (1)

[Claims] 1. A crosslinked polymer with a low crosslinking density obtained by copolymerizing a monomer mixture containing 0.05 to 1% by weight of a crosslinkable monomer, and 10% by weight of a crosslinkable monomer. It consists of porous crosslinked polymer fine particles consisting of a crosslinked polymer with a high crosslinking density obtained by copolymerizing a monomer mixture containing ~50% by weight, and the particle size is 2 to 30 μm and the standard deviation of the particle size distribution is 1 μm. Fine particles with a uniform particle size that are as follows, solvent resistant and porous. 2. (A) Adding water and a non-crosslinking monomer to an aqueous dispersion of seed particles and polymerizing them, and using the resulting particles as the next seed particle to further grow the diameter, is a non-crosslinking method. A non-crosslinked polymer obtained by treating a monomer in an aqueous medium is used as an initial seed particle twice or more, and the particle size is 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 copolymerizing it in an aqueous medium to obtain a precursor of porous crosslinked polymer fine particles, (B) The particle size is 2 to 30 μm, the standard deviation of the particle size distribution is 1 μm or less, and the porous crosslinked polymer particles are solvent resistant and porous. A method for producing fine particles of uniform particle size. 3. The method according to claim 2, which uses an emulsifier. 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 2, wherein 000 parts by weight are used. 5. The method according to claim 2, wherein the monomer mixture containing 50 to 10% by weight of the crosslinkable monomer contains a polymerization initiator. 6. The method according to claim 2, wherein a monomer mixture containing 50 to 10% by weight of a crosslinkable monomer is added in an emulsified state to an aqueous dispersion of crosslinked polymer fine particles.