JPH01234401A - Production of polymer fine granule - Google Patents

Abstract

PURPOSE:To obtain the title granules with high monodisperse nature within a reasonable size range, excellent in dispersion stability, by emulsion polymerization, in the presence of seed granules, of a vinyl monomer mixture containing a specific group-carrying vinyl monomer. CONSTITUTION:The objective polymer fine granules with a size of pref. 0.03-3mum and the size dispersion degree of <=5% can be obtained by emulsion polymerization of a vinyl monomer mixture containing normally 0.5-5wt.% of a vinyl monomer (e.g., stylenesulfonic acid, 2-sulfoethyl methacrylate) having group(s) of the formula -SO3X (X is H, alkali metal or NH4) and/or the formula -OSO3X in the presence of seed granules such as of styrene polymer with a size of prep. 0.05-0.7mum. Said polymer fine granules is suitable as standard granules for use in granulometers, granule counters, etc., and the calibration of said counters, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for producing fine polymer particles suitable as standard particles used in the calibration of particle measuring instruments such as particle size meters and particle counters.

[Prior art] Conventionally, the size and number of particles in various media have been measured using particle measuring instruments such as the Coulter principle method, light shielding method, and light scattering method, but it is difficult to maintain the reliability of measurements. In order to achieve this goal, it is necessary to calibrate particle measuring instruments with high precision. For this purpose, a particle dispersion having a defined particle size or particle size and number of particles is used.

The particles dispersed in this particle dispersion liquid should (a) have excellent monodispersity within an appropriate particle size range.

(b) It has excellent dispersion stability against large dilutions with water used as a dispersion medium, electrolyte aqueous solution, etc., and particles do not aggregate with each other or adsorb to the inner wall of the container during long-term storage.

The following characteristics are required.

Conventionally, styrene monomer, styrene-
Monomer particles such as acrylic acid comonomer and styrene-methacrylic acid comonomer have been used.

Such monomer particles are usually produced by emulsion polymerization, but it is still necessary to control the particle size of the monomer particles and to impart high dispersion stability to the dispersion medium over a long period of time. It was difficult to do so.

[Problems to be Solved by the Invention] The present invention solves the problems of the prior art as described above, and provides standard particles with high monodispersity within an appropriate particle size range and excellent dispersion stability. It is an object of the present invention to provide a method for producing suitable polymer fine particles.

[Means for solving the problem] The above problem is solved by the general formula -so3 in the presence of sheet particles.
The problem is solved by producing fine polymer particles by emulsion polymerization of a vinyl monomer mixture containing a vinyl monomer having a group represented by Ru.

Materials for the monomer particles used in the sheet particles used in the present invention include styrene monomer, styrene-butadiene comonomer, styrene-acrylic acid comonomer, styrene-methacrylic acid comonomer, etc. styrenic comonomer,
Examples include (meth)acrylic monomers and comonomers such as methyl methacrylate monomer, and these monomers can be copolymerized with polyfunctional monomers such as divinylbenzene. It may be crosslinked by

The particle size of the sheet particles used in the present invention is 0.01 to 3 μm.
It is preferably selected within the range of 0.0 depending on the conditions such as the particle size of the polymer particles to be obtained.
It is selected in the range of 3 to 2 μm, more preferably 0.05 to 0.7 μm. Particle size of sheet particles is 0.01
If the particle size is less than μm, the degree of dispersion of the particle size is generally large and unstable, so that the degree of dispersion of the particle size of the resulting polymer fine particles is also large. Moreover, if the particle size exceeds 3 μm, unnecessary particles will be produced in the production of polymer fine particles, resulting in a problem that the degree of dispersion of the particle size of the obtained polymer fine particles will increase. Further, the particle size of the sheet particles is preferably uniform in order to reduce the degree of dispersion of the particle size of the obtained polymer fine particles, and the degree of dispersion of the particle size of the sheet particles used in the present invention is 10% or less, Preferably 5
% or less. The degree of dispersion herein refers to a value obtained by dividing the standard deviation value of particle diameters obtained by randomly measuring 100 or more particles on an electron micrograph by the average particle diameter.

Examples of vinyl monomers that can be used in the present invention and are polymerized in the presence of sheet particles include styrene, chlorostyrene, chloromethylstyrene, α
- methylstyrene, divinylbenzene, acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate,
Ethyl acrylate, ethyl methacrylate, acrylic acid
n-butyl, n-butyl methacrylate, acrylic acid
2-hydroxyethyl, 2-hydroxyethyl methacrylate, polyoxyethylene acrylate, polyoxyethylene methacrylate, glycidyl acrylate, glycidyl methacrylate, ethylene glycol di-acrylate, ethylene glycol di-methacrylate , tribromophenyl acrylate, tribromophenyl methacrylate, acrylonitrile, methacrylonitrile, acrolein, methacrolein, acrylamide, methacrylamide, N-methylol-acrylamide, N-methylol-methacrylamide, dimethylol acrylamide, methylenebisacrylamide, methylene bismethacrylamide, vinyl acetate, vinyl pyridine,
N-vinylpyrrolidone, vinyl chloride, vinylidene chloride,
Examples include aromatic vinyl compounds such as vinyl bromide, (meth)acrylic compounds, and halogenated vinyl compounds. Further, conjugated diene compounds such as butadiene and isoprene may also be used.

These vinyl monomers can be used alone or in combination of two or more.

The usage ratio of the vinyl monomer is 10 to 400 parts by weight, preferably 20 to 3 parts by weight, based on 100 parts by weight of the sheet particles.
00 parts by weight. If this proportion is less than 10 parts by weight, it will be difficult to control the particle size of the monomer particles obtained, and if it exceeds 400 parts by weight, unnecessary particles will be produced in the production of monomer particles. A problem arises in that the degree of dispersion of the particle size of the obtained monomer particles increases.

In the present invention, a vinyl monomer having a group represented by the general formula -3O3X and/or -0803X (where X is H1 alkali metal or NH4) is used as a part of the vinyl monomer.

Examples of such vinyl monomers include styrene sulfonic acid, divinylbenzenesulfonic acid, ethylstyrenesulfonic acid, α-methylstyrenesulfonic acid, acrylamide-N-propanesulfonic acid, sulfuric acid poloxyethylene acrylate, and 2-sulfoethyl methacrylate. , isoprene sulfonic acid, and their lithium salts, sodium salts, potassium salts, ammonium salts, and the like.

The proportion of vinyl monomers having -SO3X and/or -oso3X groups used is 0.01 to 20% by weight, preferably 0.1 to 10% by weight of the total monomers to be polymerized together with the sheet particles. %, more preferably 0.5
~5% by weight.

If the usage ratio is less than +0.01% by weight, the polymer fine particles will not have sufficient dispersion stability in the aqueous dispersion medium used as a dispersion medium such as water or an aqueous electrolyte solution, and the particles may aggregate or form on the inner wall of the container. May be adsorbed. On the other hand, if the usage ratio exceeds 20% by weight, unnecessary particles will be generated during the production of polymer fine particles, or the hydrophilicity of the polymer fine particles will be too large, causing the particles themselves to swell or crack, making them unsuitable as standard particles. It will be appropriate.

In producing the polymer fine particles of the present invention, an emulsion polymerization method is used as a polymerization method.

The polymerization initiator used in emulsion polymerization is a water-soluble radical polymerization initiator, and specific examples thereof include sodium persulfate,
Redox initiators such as potassium persulfate, ammonium persulfate, hydrogen peroxide, and combinations thereof with sodium bisulfite, sodium thiosulfate, ferrous chloride, sodium ascorbate, and the like can be mentioned. The amount of the polymerization initiator used is usually about 0.1 to 1.0 parts by weight, preferably 0.3 to 0.6 parts by weight, based on 100 parts by weight of the vinyl monomer to be polymerized when present together with the sheet particles.
Parts by weight.

In the production method of the present invention, it is particularly preferable to use a soap-free emulsion polymerization method that does not use an emulsifier, because it contains fewer impurities and can obtain polymer particles with high monodispersity. However, in order to improve the dispersion state of the sheet particles in the aqueous dispersion or the dispersion state of the obtained polymer fine particles, an emulsifier can be used as necessary. As such emulsifiers, commonly used emulsifiers can be used, including anionic surfactants such as sodium dodecylbenzenesulfonate, sodium lauryl sulfate, sodium dialkylsulfoconolinate, and formalin condensate of naphthalenesulfonic acid. Further examples include nonionic surfactants such as polyoxyethylene nonylphenol ether, polyethylene glycol monostearate, and sorbitan monostearate.

When using an emulsifier, the amount used is usually 100 parts by weight of the total amount of vinyl monomer and sheet particles.
It is 1 part by weight or less, preferably 0.5 part by weight or less.

The vinyl monomer is polymerized by being mixed with sheet particles dispersed in an aqueous medium, but there are no particular restrictions on the method of adding the vinyl monomer to the polymerization system. Any of a batch method, a divided method, or a continuous method can be used. Further, in the production method of the present invention, the vinyl monomer may be previously dispersed in an aqueous medium to form an aqueous dispersion, and this may be introduced into the polymerization system.

Water is used as the aqueous medium used in the polymerization, and may further contain a water-soluble organic solvent such as methanol, ethanol, and acetone.

The amount of water used as an aqueous medium is typically
The content is 40% by volume or more, preferably 50% by volume or more. The aqueous medium is usually used in an amount of 300 to 5,000 parts by weight based on 100 parts by weight of the vinyl monomer and sheet particles.

The temperature of the polymerization reaction varies depending on the type of vinyl monomer and polymerization initiator used, but is usually 10 to 90°C.
, preferably 30 to 80°C, and the time required for polymerization is usually about 2 to 50 hours.

The particle size of the polymer fine particles suitably used as standard particles obtained by the method described above is controlled by conditions such as the particle size of the sheet particles and the relative usage ratio of the sheet particles and the vinyl monomer, Usually 0.0
The thickness is 1 to 4.5 μm, preferably 0.03 to 3 μm.

In addition, the dispersity of the particle size of the polymer fine particles produced is 10%.
Below, it is preferably 5% or less; if it exceeds 10%, the particle size distribution becomes wide, making it unsuitable for highly accurate calibration of particle measuring instruments.

[Example] The present invention will be explained in more detail with reference to Examples below.

[Example 1: 0.35 μm target] Polystyrene particles 7 with an average particle size of 0.309 μm and a dispersity of 2.5% produced by soap-free polymerization as sheet particles
750g of latex containing 0g was heated to 75℃,
While stirring at 0 ppm, 0.5 g of potassium persulfate was added, followed by 31 g of styrene and 0.3 g of sodium styrene sulfonate, and polymerization was carried out for 3 hours.

The average particle diameter of the obtained polymer particles determined by electron micrograph was 0.350 μm, and the degree of dispersion was 2.1%.

When this polymer fine particle was measured using a Nikkiso light scattering particle size meter, the average particle size was 0.356 μm, and the dispersity was 4.5%.
was obtained, and considering the characteristics of the light scattering granulometer, it was found that the particles were sufficiently uniformly dispersed as measured by the light scattering granulometer.

Next, the particles were diluted with pure water to adjust the number of particles to about 1.000 particles/ml, and the number of particles was counted using a particle counter manufactured by Rion KLOI. The count value is 860 pieces/ml, 0
．． All counts fell within the range of 25-0.5 μm. Considering the counting efficiency, it was found that the obtained polymer fine particles were uniformly dispersed.

Furthermore, this dispersion was placed in a polyethylene container and stored at 25°C for 60 days, 50°C for 20 days, and 5°C for 20 days, and then counted again. It was found that all the counts fell within the range of .25 to 0.5 μm, indicating that the stability was very excellent.

[Comparative Example] Instead of the vinyl monomer of Example 1, emulsion polymerization was carried out using 30 g of styrene and 0.6 g of methacrylic acid, or 31 g of styrene alone, and the average particle size of each was 0.348 μm.
and 0.350 μm particles with a dispersity of 1.8% and 262% were obtained.

In the same manner as in Example 1, the aqueous dispersion with a particle number adjusted to approximately 1,000 particles/ml was measured using a particle size meter and a particle counter, and the results were as shown in the table below. The obtained polymer particles were slightly agglomerated. I found out that there is.

Furthermore, this dispersion was placed in a polyethylene container and heated to 25°C.
After 60 days of storage, measurements were taken again and the results were as shown in the table below, indicating that further aggregation occurred during storage.

[Example 2: 0.50 μm target] As sheet particles, average particle size 0.390 μm, dispersity 1
．． Latex 6 containing 47g of 9% polystyrene particles
50g, potassium persulfate 0.5g.

53 g of styrene and 0.53 g of sodium salt of 2-sulfoethyl methacrylate were added, polymerized in the same manner as in Example 1, and measured with a particle size meter. The average particle size was 0.505 μm.
Polymer fine particles were obtained which were monodispersed in water with a degree of dispersion of 1.4%.

These particles were tested for storage stability in water, dispersion stability in physiological saline, and storage stability in the same manner as in Example 1, and were found to be good.

[Example 3: 0.75 μm target] As sheet particles, average particle size 0.683 μm, dispersity 2
．． Latex 80 containing 75g of 3% polystyrene particles
0g and potassium persulfate 0.5g.

Adding 25g of styrene and 2.7g of ammonium salt of polyoxyethylene acrylate sulfate, polymerizing in the same manner as in Example 1, and measuring with a particle size meter, the average particle size was 0.754μ
Polymer fine particles were obtained which were monodispersed in water with a m1 dispersity of 1.8%.

These particles were tested for storage stability in water, dispersion stability in physiological saline, and storage stability in the same manner as in Example 1, and were found to be good.

[Effects of the Invention] According to the manufacturing method of the present invention, it has high monodispersity within an appropriate particle size range and is suitable for the calibration of particle measuring instruments such as particle size meters and particle counters that have excellent dispersion stability. Polymer microparticles suitable for the standard particles used can be obtained.

Patent applicant: Japan Synthetic Rubber Co., Ltd.

Claims (1)

[Claims] In the presence of sheet particles, a vinyl monomer mixture containing a vinyl monomer having a group represented by the general formula -SO_3X and/or -OSO_3X (where X represents H, an alkali metal or NH_4) is emulsion polymerized. A method for producing polymer fine particles, characterized in that: