JPH0572923B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to uniformly sized fine particles having a structure in which a crosslinked polymer is added to a polymer fine particle and having an uneven surface, which has a uniform particle size and excellent solvent resistance, and a method for producing the same. be. BACKGROUND OF THE INVENTION Polymer particles used as opacifying agents, matting agents, organic pigments, thickness and gap adjusting materials, 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 strongly required that the material does not dissolve or swell in the solvent. Furthermore, there are cases where particles are desired to have a large surface area, such as when used as a carrier for chromatography. Conventionally, polymer fine particles having a large surface area or having solvent resistance have been produced using a monomer such as acrylic acid or methacrylic acid and a hydrophilic vinyl monomer having two or more functional groups. Porous particles are known to be obtained by copolymerizing the polymer by a suspension polymerization method in which a small amount of an organic solvent that is soluble in the body and insoluble in the polymer is added, and then the solvent is extracted from the resulting copolymer ( (Japanese Unexamined Patent Publication No. 1988-88657). In addition, monomer mixtures containing crosslinking monomers are polymerized using a suspension polymerization method using special suspending agents or dispersed under high-speed stirring, and monomers containing catalysts are also used. Also known was a product obtained by polymerizing an aqueous dispersion containing an anionic emulsifier under homogenization treatment using a homomixer or the like (Japanese Unexamined Patent Publication No. 1983-66406). Furthermore, it is also known that a styrene emulsifier is added to a suspension of styrene polymer beads to form a new styrene polymer layer around the beads using a seeding suspension polymerization method (Unexamined Japanese Patent Publication No. Showa 57-
128708). Problems to be Solved by the Invention However, the method for producing porous particles has a particle size of 5 to 13 μm, which is poor in uniformity, and the suspension polymerization method has a particle size of about 30 μm or less. It is difficult to obtain particles with a high yield in a high yield, and it is difficult to obtain particles of 8 μm or less using a homogenization method using a homomixer, etc., and when the obtained particles have an average particle size of 8 μm, for example. However, the uniformity of the particle size is poor, with the particle size distribution ranging from 3 to 15 μm.Furthermore, in the seeded suspension polymerization method, the particle size of the obtained particles is about 30 mesh, and the fineness of the particles is poor. There were problems such as being inferior. Therefore, with conventional methods, it is not possible to obtain polymer particles with a particle size of 1 to 30 μm, a wide surface area, and excellent solvent resistance, and in order to make the particle size distribution uniform, classification treatment is performed after polymerization. is the current situation. Means for Solving the Problems The present inventors have overcome the above problems and have been able to obtain polymer fine particles having a wide surface area and excellent solvent resistance, and having a narrow particle size distribution range. As a result of intensive research to develop a production method that can produce the desired results, we have found that polymer fine particles are used as seeds, crosslinkable and non-crosslinkable monomers are absorbed into these seed particles, and they are copolymerized. The inventors have discovered that the object can be achieved by copolymerizing the particle surface to form a crosslinked polymer, and have completed the present invention. That is, the present invention contains a crosslinked polymer formed by copolymerizing a crosslinkable monomer and a non-crosslinkable monomer inside the polymer fine particles, has an uneven surface, and has a particle size of 1. The standard deviation of the particle size distribution is ~30 μm.
Fine particles with a uniform particle size of 1 μm or less, solvent-resistant, and containing no pores in the body, and particles with a particle size of 20 μm or less with a standard deviation of particle size distribution.
An aqueous dispersion of a monomer mixture consisting of a crosslinking monomer and a non-crosslinking monomer is added to a dispersion of fine polymer particles of 0.5 μm or less in an amount of 100 to 100 parts by weight of the monomer mixture per 100 parts by weight of the fine polymer particles. The present invention provides a method for producing the above-mentioned uniform particle diameter particles, which comprises adding 3,000 parts by weight of the polymer and polymerizing the particles by rapidly heating the mixture to the decomposition temperature of the initiator in the presence of an oil-soluble polymerization initiator. The polymer fine particles used in the present invention have a particle size of 20 μm or less, preferably 0.4 to 15 μm,
Standard deviation of particle size distribution is 0.5μm or less, preferably
The particle size can be 0.2 μm or less, and non-porous particles that do not contain pores inside the particles are used. This makes it possible to form fine particles of uniform size that do not contain pores in the body, which is a target product that has excellent uniformity in particle size and can be used for practical purposes without being classified. In the present invention, the polymer fine particles may be non-crosslinked ones made of styrene, acrylic, or methacrylic polymers, but are preferably to the extent that they can swell with the monomer mixture used in terms of solvent resistance. It is a cross-linked product. This crosslinked polymer fine particle is
For example, it can be obtained as follows. That is, the non-crosslinkable monomer and the crosslinkable monomer are easily dispersed in emulsifier-containing water or emulsifier-free water, and polymerized in the coexistence with a water-soluble polymerization initiator (emulsion polymerization, non-emulsion polymerization). can be obtained. In this case, a polymerization method that does not use an emulsifier is preferable because the particle size of the polymer obtained is larger. In addition, the polymer in the emulsion obtained by the usual emulsion polymerization method is used as a seed particle, and it is mixed with a dispersion medium, a crosslinking monomer, a non-crosslinking monomer, and an emulsifier in the amount necessary to stabilize the polymerization reaction (surface The tension
It is preferable to set it to 55 dyne/cm or more. ) and a polymerization initiator for polymerization, which is repeated once or twice or more if necessary, to form particles larger than the initial seed particles. Particles obtained by this method have a more uniform particle size distribution and can therefore be preferably used in the present invention. In this case, as monomers, monomers that themselves or their polymers do not dissolve in water can be preferably used. If it is soluble in water, polymerization will proceed in water, making it difficult to grow the particle size of seed particles, etc., and making it easier to form new particles, which is undesirable. Examples of non-crosslinking monomers that can be preferably used include styrenic monomers such as styrene, methylstyrene, and ethylstyrene; Examples include acrylic acid or methacrylic acid ester monomers having four or more alkyl groups. The non-crosslinking monomers, like the crosslinking monomers described below, can be used alone or in combination of two or more, and are selected and used depending on the intended use of the crosslinked polymer fine particles and even uniform particle size particles. Ru. For example, when used in various thickness and gap adjustment materials and carriers for chromatography, the fine particles are required to have pressure resistance, so styrene diameter monomers with a high polymer glass transition point are particularly suitable. There is. On the other hand, examples of crosslinkable monomers include monomers having two or more ethylenic double bonds, such as trimethylolpropane triacrylate, diethylene glycol dimethacrylate, and divinylbenzene. Among these, those having low solubility in water, such as divinylbenzene, are preferably used. This is because particles with high water solubility generate new particles other than seed particles during the polymerization process. As mentioned above, the crosslinked polymer fine particles preferably used in the present invention are those that can be swollen by the monomer used, but this is because the non-crosslinkable monomer is, for example, 99 to
This can be achieved by mixing at a ratio of 99.95% by weight and 1 to 0.05% by weight of the crosslinkable monomer, and copolymerizing by the above-mentioned method such as emulsion polymerization method. The degree of swelling, defined as the volume ratio of the particles after swelling to that before swelling, of the crosslinked polymer fine particles obtained by copolymerizing at this usage ratio is usually 8 to 100, and the swelling degree of this degree is the present invention. It is suitable for In addition, if the proportion of the crosslinkable monomer used is too large, a product with too low degree of swelling (excessive crosslinking density) will be obtained, and the polymerization process when providing the crosslinked polymer in the crosslinked polymer fine particles will be difficult. In this case, the monomer cannot be sufficiently diffused into the particles, resulting in insufficient polymerization in the fine particles, and new particles are generated in addition to the fine particles, making it difficult to fully achieve the object of the present invention. As the crosslinkable monomer and non-crosslinkable monomer used in the present invention, the same ones as in the case of the crosslinked polymer fine particles described above can be mentioned. The appropriate ratio of the crosslinking monomer to the non-crosslinking monomer is 0.1 to 1 mole, preferably 0.2 to 0.8 mole, of the crosslinking monomer per mole of the non-crosslinking monomer. If the proportion of the crosslinkable monomer used is less than 0.1 mole, the crosslink density of the crosslinked polymer formed will be too low.
On the other hand, if the amount exceeds 1 mole, the crosslink density of the crosslinked polymer becomes too high, making it difficult to achieve the object of the present invention. In the method of the present invention, the above-mentioned crosslinkable monomer and non-crosslinkable monomer are added to the above-mentioned dispersion of polymer fine particles in the form of an aqueous dispersion of a mixture thereof. The addition ratio is per 100 parts by weight of polymer fine particles.
The amount of the mixture of both monomers is 100 to 3000 parts by weight, preferably 150 to 2500 parts by weight. If the addition ratio is less than 100 parts by weight, the resulting fine particles of uniform particle size will have insufficient solvent resistance, while if it exceeds 3,000 parts by weight, the weight will tend to increase in areas other than the polymer fine particles, which is undesirable. Further, the proportion of the crosslinkable monomer in the monomer mixture of both monomers, that is, the crosslinkable monomer and the non-crosslinkable monomer, is suitably 10 to 50% by weight. If a crosslinking monomer that is easily soluble in water is used as the monomer, the monomer will not effectively penetrate into the polymer fine particles, and new particles will often be generated in addition to the fine particles. Therefore, a material that is sparingly soluble in water, such as divinylbenzene, can be preferably used. Furthermore, for the same reason, a non-crosslinking monomer that is sparingly soluble in water can be preferably used. Therefore, a preferred combination in the present invention is a combination of a crosslinked polymer that is poorly soluble in water, such as a crosslinked polymer and a crosslinked polymer fine particle made of a styrene monomer and divinylbenzene. The combination of the above-mentioned styrene monomer and divinylbenzene has a high glass transition temperature based on them, so it is suitable for use in cases where pressure resistance is particularly required, such as when used as a chromatography carrier. It has advantages suitable for various uses. In the method of the present invention, an aqueous dispersion of a monomer mixture is added to a dispersion of fine polymer particles, and the copolymerization reaction is carried out by rapidly heating to the decomposition temperature of the initiator in the presence of an oil-soluble polymerization initiator. let As a result, at the same time as the monomer mixture penetrates into the polymer fine particles and the subsequent copolymerization occurs, the polymerization of the oil droplets of the monomer mixture proceeds in the vicinity of the fine particles, and active species based on the polymerization initiator are formed. The oil droplets come into contact with the polymer fine particles and react with the monomers that have penetrated (absorbed) into the fine particles. Therefore, if the oil droplet size of the monomer mixture is uniform, irregularities based on the crosslinked polymer having a regular size will be formed on the surface of the polymer fine particles, resulting in particles with a large surface area. . Furthermore, based on the above, a crosslinked polymer that does not contain pores within the inner diameter is formed inside and outside the polymer fine particles, and a state in which the inner diameter does not contain pores is maintained, thereby obtaining uniform-sized fine particles of the target object. It should be noted that the smaller the oil droplets of the monomer mixture, and the easier they are in contact with the fine polymer particles, the more convenient it is in the present invention.
Preferably, the minimum necessary amount of emulsifier is added and the dispersion is treated with ultrasonic waves to form an emulsion, so that the oil droplets are
It is preferable to add the monomer mixture in a state where the size is 0.1 to 0.5 μm. From this point of view, the particle size of polymer fine particles is 0.5 μm or more, especially
It is preferable that the thickness is 1 μm or more. By making the oil droplets of the monomer mixture relatively small with respect to the polymer fine particles,
This is to improve the efficiency of increasing the surface area. On the other hand, as the polymerization initiator for carrying out the above-mentioned polymerization reaction, an oil-soluble radical initiator is usually used. If it is water-soluble, new particles may be generated in addition to the seed particles, which may cause problems. In order to smoothly carry out copolymerization, it is preferable that the polymerization initiator be used in a form of 0.1 to 3% by weight dissolved in the monomer or a mixture thereof. By carrying out the polymerization reaction as described above, the particles having a crosslinked polymer in the fine polymer particles of the present invention and having the crosslinked polymer in an uneven state on the surface of the fine polymer particles have a particle size of 1 to 30 μm. , preferably 1
~20 μm, the standard deviation of the particle size distribution is 1 μm or less, preferably 0.5 μm or less, and it is possible to obtain uniformly sized fine particles that have a wide surface area, excellent solubility, and uniform particle size, and do not contain pores in the body. It will be done. The crosslinked polymer in the uniform particle size fine particles may or may not be chemically bonded to the fine particles. Effects of the Invention The uniform particle size fine particles of the present invention have a crosslinked polymer on the surface in an uneven manner and also on the inside, so they have a wide surface area, excellent solvent resistance, and uniform particle size. It is excellent. Furthermore, it has a structure that does not contain any pores inside the body, and has excellent strength such as pressure resistance. Further, according to the method of the present invention, the uniform particle size fine particles can be obtained in a high yield and in a state with excellent particle size uniformity, and products that can be used for practical purposes can be manufactured without performing classification treatment. It has advantages. Reference Example 1 After dispersing 30 parts of styrene in which 0.25% (by weight, the same below) of divinylbenzene was dissolved in 70 parts of ion-exchanged water in which 0.6 parts (by weight, the same below) of sodium lauryl sulfate was dissolved. This was heated to 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 temperature was maintained at 70°C for 8 hours to form a dispersion of polymer particles. Obtained. The particle size of the polymer particles was 0.043 μm, and the standard deviation of the particle size distribution was 0.01 μm. Next, 10 parts of the obtained dispersion of polymer particles and 65 parts of ion-exchanged water were mixed and the temperature was raised to 70°C, and then 30 parts of styrene in which 0.25% divinylbenzene was dissolved was added and stirred for 1 hour. , then potassium persulfate
Add 5 parts of ion-exchanged water in which 0.03 part of
C. for 8 hours to obtain an aqueous dispersion of polymer particles having a particle size of 0.149 .mu.m and a standard deviation of the particle size distribution of 0.012 .mu.m. Furthermore, using the obtained dispersion liquid, seed polymerization was carried out with the composition shown in Table 1 to obtain an aqueous dispersion of polymer particles.

[Table] In this way, a dispersion B of loosely crosslinked crosslinked polymer fine particles having a good particle size distribution and containing no pores in the body, which is used in the present invention, was obtained. The degree of swelling of the fine particles in the dispersion B obtained here with respect to the styrene monomer was measured to be 15. Reference Example 2 A dispersion of crosslinked polymer fine particles shown in Table 2 was obtained in the same manner as in Reference Example 1.

[Table] Example 1 120 parts of ion-exchanged water and 8 parts of a 10% aqueous solution of polyvinyl alcohol (Kuraray Poval 224, degree of saponification 88%, manufactured by Kuraray Co., Ltd.) were added to 10 parts of the dispersion of Reference Example 1B, and the mixture was stirred uniformly. , 0.5 part of benzoyl peroxide was dissolved in 48 parts of a monomer mixture consisting of 65% styrene and 35% divinylbenzene, and 180 parts of ion-exchanged water was added.
1 part and 0.018 part of sodium lauryl sulfate were mixed and treated with ultrasound to make an emulsion, and
Polymerize at 80°C for 9 hours under a nitrogen stream while stirring,
A dispersion of fine particles of uniform particle size without containing pores in the body was obtained. The particle size of the fine particles was 1.9 μm, and the standard deviation of the particle size distribution was 0.12 μm. After drying the fine particles, they were immersed in various solvents and stored at 50°C for 800 hours, after which the weight increase rate was examined. The results are shown in Table 3.

[Table] Furthermore, no elution of the polymer into the solvent was observed, the solvent resistance was good, and the surface roughness was also good when observed with an electron microscope. Example 2 120 parts of ion-exchanged water and 5 parts of a 10% polyvinyl alcohol aqueous solution were added to 10 parts of the dispersion of Reference Example 2F, stirred uniformly, and then mixed with 75% styrene and divinylbenzene.
200 parts of ion-exchanged water in which 0.6 parts of benzoyl peroxide was dissolved in 60 parts of a monomer mixture consisting of 25%;
Add 0.016 parts of sodium lauryl sulfate and apply ultrasonic treatment to make an emulsion. Polymerize with stirring at 80°C under a nitrogen stream for 9 hours to disperse fine particles with a uniform size and no pores in the body. I got the liquid. The particle size of the fine particles was 7.7 μm, and the standard deviation of the particle size distribution was 0.30 μm. Moreover, its solvent resistance was also excellent. Furthermore, as is clear from the attached electron micrograph, the surface was uneven and had an excellent wide surface area.

[Brief explanation of the drawing]

The photograph is an electron micrograph (2000x magnification) of an example of the present invention.

Claims (1)

[Scope of Claims] 1 A crosslinked polymer formed by copolymerizing a crosslinkable monomer and a non-crosslinkable monomer is contained inside the polymer fine particles, and the surface is uneven, and the particle size is is 1~
Uniform particle size particles with a particle size distribution of 30 μm and a standard deviation of 1 μm or less, solvent resistant, and containing no pores in the body. 2 When the particle size is 20 μm or less, the standard deviation of the particle size distribution is
An aqueous dispersion of a monomer mixture consisting of a crosslinking monomer and a non-crosslinking monomer is added to a dispersion of fine polymer particles of 0.5 μm or less in an amount of 100 to 100 parts by weight of the monomer mixture per 100 parts by weight of the fine polymer particles. 3,000 parts by weight of a crosslinkable monomer and a non-crosslinkable monomer are polymerized by adding 3000 parts by weight and rapidly heating to the decomposition temperature of the initiator in the coexistence of an oil-soluble polymerization initiator. Contains a crosslinked polymer formed by polymerization inside the polymer fine particles, has an uneven surface, has a particle size of 1 to 30 μm, has a standard deviation of particle size distribution of 1 μm or less, and is solvent resistant. , a method for producing uniformly sized fine particles that do not contain pores in the body. 3 Monomer mixture contains 10 to 50% by weight of crosslinkable monomer
3. The method according to claim 2, which contains an oil-soluble polymerization initiator dissolved therein.