JPH06822B2 - Method for producing monodisperse vinyl polymer fine particles - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing monodisperse vinyl polymer fine particles,
In particular, it relates to a method for producing monodisperse vinyl polymer fine particles having a relatively large particle size and a uniform particle size.

In the conventional emulsion polymerization, when obtaining a monodisperse latex having a uniform particle size, the maximum particle size is generally 0.5 μm.
It was about m. Conventionally, as means for increasing the particle size of polymer fine particles obtained by emulsion polymerization, (1)
It is known to reduce the amount of emulsifier, (2) reduce the amount of polymerization initiator, and (3) add an inorganic electrolyte. These methods have the drawbacks that the emulsion polymerization stability is reduced, and that even if polymer fine particles having a large particle size are obtained, the particle size becomes polydisperse. As means for improving these drawbacks, for example, as described in JP-A-59-22904,
A method for controlling the concentration of the inorganic electrolyte, or a method for obtaining a latex of a styrene-acrylamide copolymer by using a solvent in combination with water, as described in Proceedings of the Society of Polymer Science, Vol. 34, has been proposed. There is.

Problems to be Solved by the Invention However, in the above method for controlling the concentration of the inorganic electrolyte, it was not possible to obtain particles having a particle size of 1 μm or more. Further, the method of obtaining a latex of styrene-acrylamide copolymer by using a solvent in combination with water gives particles having a particle size of 1 μm or more, but is applicable to monomers other than styrene and acrylamide used for the polymerization. Therefore, it could not be used for various purposes.

In view of the above situation, the inventors of the present invention have made extensive studies on a method for producing polymer fine particles having a particle size of 1 μm or more and having an extremely narrow particle size distribution, and as a result, have completed the present invention.

Therefore, an object of the present invention is to provide a method for producing monodisperse vinyl polymer particles having a large particle size and an extremely narrow particle size distribution.

Another object of the present invention is to provide a method for producing polymer fine particles without being greatly restricted by the type of monomer used as a raw material.

Means and Actions for Solving Problems In order to increase the particle size and maintain monodispersity, the present inventors have found that the type and concentration of the polymerization initiator, the type and concentration of the electrolyte, and the polymerization temperature. In addition, it was found that the surfactant used at the time of polymerization is also an important factor, and as a result of diligent studies, it was found that when the compound represented by the following general formula (I) is used and the polymerization is carried out under specific conditions, It has been found that, and particularly good results are obtained when used in a copolymerization system using a silicon atom-containing vinyl monomer, leading to the completion of the present invention. .

That is, the method for producing monodisperse vinyl polymer fine particles of the present invention,
One or more monomers selected from the group consisting of vinyl aromatic compounds, acrylic acid esters and methacrylic acid esters 99.9% to 60.0% by weight, and a silicon atom-containing vinyl compound 0.1 to 40% by weight. % In the presence of a compound represented by the following general formula (I) as a surfactant, and a persulfate salt of 10 ⁻¹ to 10 ⁻³ as a polymerization initiator.
Mol / and divalent metal sulfate as electrolyte 10 ^-2 to 10
It is characterized in that the polymerization is carried out at ^-4 mol / mol. As a result, monodisperse vinyl polymer fine particles having a number average particle size of 1.0 to 10.0 μm and a particle size distribution with a standard deviation of 1.25 or less by a Coulter counter can be obtained.

(In the formula, R ₁ and R _{2, which} may be the same or different, each represents an alkyl group having 4 to 8 carbon atoms, a substituted or unsubstituted phenyl group, or a substituted or unsubstituted cyclohexyl group, and M Represents an alkali metal) Hereinafter, the present invention will be described in detail.

In the present invention, examples of the silicon atom-containing vinyl monomer include those represented by the following general formulas (II) and (III).

(In the formula, R ₁ , R ₂ and R ₃ each represent a hydrogen atom, an alkyl group having 1 to 8 carbon atoms or a phenyl group, and R ₄ represents a hydrogen atom or a methyl group.) Silicon atom-containing monomer Because of its low surface tension,
It acts to improve the retention of the emulsion. In the present invention, the silicon atom-containing monomer is used in the range of 0.1 to 40% by weight based on all the monomers. If the amount of the silicon-containing monomer is less than 0.1% by weight, the effect of improving the stability of the emulsion during emulsion polymerization cannot be expected, and if it is more than 40% by weight, a copolymer having desirable properties cannot be obtained. .

In the present invention, the major component constituting the vinyl copolymer is one or more selected from the group consisting of vinyl aromatic compounds such as styrene, acrylic acid esters and methacrylic acid esters, and all monomers. Against 9
It is used in the range of 9.9 to 60.0% by weight.

In the present invention, the polymerization may be carried out in one step, but it may be carried out in two steps. For example, first, a method of polymerizing only styrene, followed by adding styrene and a silicon-containing vinyl monomer to continue the polymerization reaction, or when using a hydrophilic monomer such as methyl methacrylate, First, a method is used in which styrene, 2-ethylexyl acrylate, etc. are polymerized, and after the particle size / potential balance reaches equilibrium, methyl methacrylate and a silicon-containing vinyl monomer are added to carry out polymerization. it can.

The emulsion polymerization reaction is carried out in the presence of the compound represented by the general formula (I), and specific compounds include the following.

The addition amount of these compounds can be set arbitrarily, but it is particularly preferable to use them in the aqueous solution concentration range of 0.04 to 0.80 g / dl.

In emulsion polymerization, the surfactant properties required to increase the particle size and maintain monodispersity are 1) have a higher surface tension than commonly used sodium dodecyl sulfate, etc. The conditions are that the number of repetitions of generation / disappearance is as small as possible, and 3) the surface charge is sufficient. The above 1) is a condition for controlling polydispersion (generation of fine particles) by generating conditions for increasing the particle size, and 3) is polydispersion by preventing interparticle bonding (for coarse particles). This is a condition for controlling (generation). The surfactant represented by the general formula (I) used in the present invention satisfies the above conditions. That is, compared with a linear activator such as sodium dodecyl sulfate which has been conventionally used, the generation and disappearance of the emulsion are less repeated, and the number of carbon atoms in the alkyl group is 4 to 8 to reduce the particle size and the surface. This makes it easy to balance the electric potential.

In the present invention, a persulfate-based initiator is used as the polymerization initiator, and for example, potassium persulfate, ammonium persulfate and the like are most preferably used. In this case, it is necessary to use the aqueous solution in the concentration range of 10 ^-1 to 10 ^-3 mol /. If it deviates from this range, monodisperse vinyl polymer fine particles having a predetermined particle size and standard deviation cannot be obtained.

In the present invention, divalent metal phosphates such as cuprous sulfate (CuSO ₄ ) and ferrous sulfate (FeSO ₄ ) are used as the electrolyte, whereby the average particle size of the polymer fine particles is increased. Becomes larger and the particle size distribution becomes sharper. The concentration of the electrolyte needs to be in the range of 10 ⁻² to 10 ⁻⁴ mol /. Outside this range, monodisperse vinyl polymer fine particles having a predetermined particle size and average deviation cannot be obtained.

Further, together with the surfactant represented by the general formula (I),
A water-soluble polymer such as an acrylic acid-maleic acid copolymer may be used as a dispersion stabilizer. In that case, the surface tension is 4
It should be between 0 and 75 dynes / cm.

The polymerization temperature is 40 to 90 ° C, preferably 45 to 75 ° C.

Examples Hereinafter, the present invention will be described with reference to Examples. All of the following examples were carried out using a 5 glass-lined autoclave equipped with an N ₂ inlet, an anchor type stirring blade, and a temperature controller.

Example 1 Distilled water 3.2 was placed in a reactor and replaced with nitrogen gas, and then the temperature was raised to 50 ° C. To this was added an aqueous solution obtained by dissolving 4.32 g of the following compound and 0.72 g of an acrylic acid-maleic acid copolymer (Poise 520 manufactured by Kao Corporation) in 0.2 water.

Then, an aqueous solution obtained by dissolving 28.8 g of ammonium persulfate in 0.2 of water was added. Furthermore, styrene 40
0 ml and 0.6 g of cuprous sulfate were added, and the polymerization temperature was 50 ° C.
Polymerization was carried out for 4 hours while maintaining After 4 hours, a mixed solution of 400 ml of styrene and 20 ml of polydimethylsiloxane macromer (FM-0700, manufactured by Chisso Corporation) (n = 1, m = 3 in the general formula (II)) was added dropwise, and further 40 hours. The polymerization was continued.

The obtained particles had a size of 4.0 μm and were monodisperse, and the standard deviation of the particle size distribution by a Coulter counter was 1.14. The polymer fine particles had a weight average molecular weight of 33600 and a number average molecular weight of 94,000.

Comparative Example 1 Polymerization was carried out in the same manner as in Example 1 except that the dimethylsiloxane macromer FM-0700 was not used, and the particle size of the obtained particles was 3.0 to 5.5 μm, showing large variations. .

Example 2 Dimethylsiloxane macromer used in Example 1
Polymerization was performed in the same manner except that FM-0700 was replaced with dimethylsiloxane macromer (manufactured by Chisso Corporation) (n = 1, m = 3 in the general formula (II)). The polymer fine particles obtained had a number average diameter of 3.4 μm and a standard deviation in particle size distribution of 1.14. The polymer fine particles were gelled.

Example 3 Dimethylsiloxane macromer used in Example 1
FM-0700 is a dimethylsiloxane macromer FM-0711 (manufactured by Chisso Corporation) (general formula (II) average molecular weight 1000, m = 3)
Polymerization was performed in the same manner except that the substitution was performed with. The number average particle size of the obtained polymer fine particles was 4.2 μm, and the standard deviation in the particle size distribution was 1.12. The polymer fine particles had a polymerization average molecular weight of 318,000 and a number average molecular weight of 88,000.

Effect of the Invention According to the present invention, the number average particle size of 1.
Monodisperse polymer fine particles having extremely large particles of about 0 to 10.0 μm and having a narrow particle size distribution with a standard deviation of 1.25 or less can be easily obtained without requiring complicated steps.

In addition, the polymer fine particles obtained by the present invention include biological carriers, immobilized enzyme carriers, immunoserologic diagnostic drug carriers, drug administration carriers, ion exchange resins, crystal display spacers, column packing materials, and electron carriers. It can be applied to a photographic developer, a paint, etc., and particularly colored polymer fine particles can be used as an electrophotographic developer as they are, which is advantageous.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location C08F 230/08 MNU 7242-4J 299/08 MRY 7442-4J

Claims (1)

[Claims] 1. 99.9% to 60.0% by weight of at least one monomer selected from the group consisting of vinyl aromatic compounds, acrylic acid esters and methacrylic acid esters, and a silicon atom-containing vinyl compound 0 1 to 40% by weight in emulsion polymerization, in the presence of a compound represented by the following general formula (I) as a surfactant, persulfate 1 as a polymerization initiator
A method for producing fine particles of monodispersed vinyl polymer, characterized in that polymerization is carried out using 0 ^-1 to 10 ^-3 mol / and a divalent metal sulfate of 10 ^-2 to 10 ^-4 mol / as an electrolyte. (In the formula, R ₁ and R _{2, which} may be the same or different, each represents an alkyl group having 4 to 8 carbon atoms, a substituted or unsubstituted phenyl group, or a substituted or unsubstituted cyclohexyl group, and M Represents an alkali metal)