JPH11228625A - Preparation of polymer fine particle dispersion - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for obtaining a non-aqueous medium dispersion liquid of hydrophobic polymer fine particles without the necessity of a load-intensive facility as in the prior art. SOLUTION: A polymerizable monomer having a vinyl group (here, the monomer does not have an ionic group) and a polymerizable monomer having an anionic group or a cationic group, After copolymerization by suspension polymerization in an aqueous medium to obtain polymer fine particles, the surface of the polymer fine particles is made hydrophobic by forming an ion complex with a hydrophobizing agent having a charge opposite to the ionic group in the polymer. And a step of replacing the aqueous medium with a non-aqueous medium to obtain a non-aqueous medium dispersion of polymer fine particles.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a polymer fine particle dispersion, and more particularly, to a polymer in which polymer fine particles are dispersed in a non-aqueous medium without going through complicated steps such as drying / crushing / mixing. The present invention relates to a method for easily obtaining a fine particle dispersion.

[0002]

2. Description of the Related Art A polymer fine particle dispersion in which polymer fine particles are dispersed in a non-aqueous medium has been widely used in various applications, for example, in the fields of paints, chemicals, household goods, cosmetics, etc. It is used as a lubricant and a lubricant, and its importance has been increasing in recent years. Generally, polymer particles are synthesized in an aqueous medium by a method such as suspension polymerization or emulsion polymerization. When synthesized in an aqueous medium, the water-soluble dispersant or surfactant to be used remains on the surface of the polymer fine particles, resulting in surface hydrophilic particles. When the polymer fine particles thus obtained are dispersed in a desired non-aqueous medium, it is necessary to perform a surface hydrophobic treatment. In that case, the dispersant or surfactant used at the time of synthesizing the polymer fine particle dispersion is washed away, dried,
After crushing or the like to form primary particles, the particles are generally subjected to a hydrophobic treatment and dispersed in a non-aqueous medium.

As described above, the conventional method for producing a polymer fine particle dispersion in which the polymer fine particles are dispersed in a non-aqueous medium has many complicated steps, takes a long time, and is disadvantageous in cost. Therefore, simplification of the process has been desired. Accordingly, the problem to be solved by the present invention is to provide a method for obtaining a non-aqueous medium dispersion of hydrophobic polymer fine particles without the need for a load-intensive facility as in the prior art.

[0004]

The present invention provides a polymerizable monomer having a vinyl group (here, the monomer does not have an ionic group; hereinafter, referred to as monomer A) and an anion. A polymerizable monomer having a functional group or a cationic group (hereinafter, referred to as monomer B) is copolymerized by suspension polymerization in an aqueous medium to obtain polymer fine particles, and then the ionic polymer in the polymer is obtained. By forming an ion complex with a hydrophobizing agent having a charge opposite to the group, a step of hydrophobizing the surface of the polymer fine particles and a step of replacing the aqueous medium with a non-aqueous medium, Provided is a method for producing a non-aqueous medium dispersion of polymer fine particles.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, first, a monomer A and a monomer B are copolymerized by suspension polymerization in an aqueous medium.
Obtain polymer microparticles. In this case, the monomer A is not particularly limited as long as it has a vinyl group and no ionic group, and may be an aromatic vinyl-based monomer such as styrene, ethylvinylbenzene, α-methylstyrene, and vinylpyridine. Monomer, methyl (meth) acrylate, ethyl (meth) acrylate, t-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, benzyl (meth) acrylate, cyclohexyl Various (meth) acrylate monomers such as (meth) acrylate and methoxyethyl (meth) acrylate, vinyl acetate,
Vinyl ester monomers such as vinyl propionate and vinyl pivalate, cyan monomers such as acrylonitrile and methacrylonitrile, amide monomers such as acrylamide and methacrylamide, and halogen monomers such as vinyl chloride and vinylidene chloride Monomers, α-olefin monomers such as ethylene, propylene, isobutylene, 1-butene and 1-hexene, conjugated double bond-containing monomers such as butadiene and isoprene, ethyl vinyl ether, butyl vinyl ether and hexyl vinyl ether And vinyl ether monomers such as cyclohexyl vinyl ether, and at least one of these can be used.

[0006] Examples of the anionic group in the monomer B include a carboxyl group, a sulfo group and a phosphate group. As the carboxyl group-containing monomer, acrylic acid,
Examples include carboxylic acid-containing monomers such as methacrylic acid, maleic acid and itaconic acid, and dicarboxylic acid ester monomers such as monomethyl maleate, monobutyl maleate and monomethyl itaconate. Examples of the sulfo group-containing monomer include styrenesulfonic acid, acryloyloxyalkylsulfonic acid, methacryloyloxyalkylsulfonic acid, acrylamidoalkylsulfonic acid, and methacrylamidoalkylsulfonic acid. Examples of the phosphoric acid group-containing monomer include 2-acryloyloxyethyl phosphoric acid, 2-methacryloyloxyethyl phosphoric acid, 2-acryloyloxyethoxyethyl phosphoric acid, and 2-methacryloyloxyethoxyethyl phosphoric acid.

On the other hand, examples of the polymerizable monomer having a cationic group include polymerizable monomers having a primary amine, a secondary amine, a tertiary amine, a quaternary ammonium salt, and the like. Specific examples include dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dimethylaminopropylacrylamide, 2- (methacryloyloxy) ethyltrimethylammonium chloride, and the like. At least one of these can be used.

If the amount of the monomer B is too small, it is difficult to form an ion complex, and it is difficult to disperse the polymer particles in a non-aqueous medium. If the amount is too large, the suspension polymerization tends to be unstable. Since the particles are easily aggregated in a non-aqueous medium, the content is preferably 0.1 to 30% by weight, more preferably 0.3 to 20% by weight, particularly preferably 0.5 to 10% by weight, based on the total weight of the monomers A and B.

The aqueous medium in the present invention means water or a mixture of water and a lower alcohol (methanol, ethanol, etc.). When copolymerizing the monomer A and the monomer B, it is preferable to use a crosslinking agent. The crosslinking agent is not particularly limited as long as it can be dissolved in the monomer, and examples thereof include divinylbenzene, polyethylene glycol diacrylate, 1,3-butylene glycol diacrylate, and 1,4-butylene glycol diacrylate. 1,6-hexylene glycol diacrylate, neopentyl glycol diacrylate, methylene bisacrylamide, trimethylolpropane triacrylate, trimethylolethane triacrylate, tetramethylolmethane triacrylate, ditrimethylolpropane tetraacrylate, pentaerythritol tetraacrylate, Ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, polyethylene glycol dimethacrylate 1,3-butylene glycol dimethacrylate, 1,4-butylene glycol dimethacrylate, 1,6-hexane glycol dimethacrylate, neopentyl glycol dimethacrylate, dipropylene glycol dimethacrylate, polypropylene glycol dimethacrylate, 2,2 '-Bis (4-methacryloxydiethoxyphenyl) propane, trimethylolpropane trimethacrylate, trimethylolethanetrimethacrylate and the like can be mentioned, and at least one of these can be used. The amount of the crosslinking agent used is not particularly limited, but is preferably 0.1 to 0.1% based on the total weight of the monomers A and B.
It is 50% by weight, particularly preferably 10 to 30% by weight.

In the suspension polymerization of the present invention, conventionally known dispersants such as polyvinyl alcohol and polyvinyl pyrrolidone are usually used. From the viewpoint of forming an ion complex between the polymer fine particles obtained by the suspension polymerization and the hydrophobizing agent, it is preferable to reduce the dispersant used during the suspension polymerization and suppress the inhibition of the hydrophobization treatment. When a large amount of the dispersant is adsorbed on the surface of the polymer fine particles, the reaction between the ionic group present on the surface of the polymer fine particles and the hydrophobizing agent is hindered. The use amount of the dispersant is preferably 10% by weight or less, more preferably 3% by weight or less, particularly 0.3-1.
0% by weight is preferred.

In the suspension polymerization of the present invention, the method of dispersing the mixture of the above monomers in an aqueous medium is not particularly limited,
Depending on the desired particle size, a dispersion method using various kinds of rotating blades such as an anchor blade, a Faudler blade, and a turbine blade, and a mechanical dispersion method such as a homomixer can be appropriately used.

The polymerization initiator used in the suspension polymerization is not particularly limited as long as it is used in ordinary suspension polymerization. Benzoyl peroxide, lauroyl peroxide, di-t
-Butyl peroxide, cumene hydroperoxide, t
Peroxide such as -butylperoxy 2-ethylhexanoate, azobisisobutyronitrile, 2,2'-azobis (2,4-dimethylvaleronitrile), 2,2'-azobis (4-methoxy-2 Azo compounds such as 2,4-dimethylvaleronitrile) and dimethyl 2,2'-azobisisobutyrate, and at least one of these is used.

The reaction temperature in the suspension polymerization depends on the decomposition temperature of the initiator used, but is usually 30 to 90 ° C., preferably 30 to 90 ° C.
Performed at 50-80 ° C. The particle size of the polymer fine particles obtained by the suspension polymerization is not particularly limited depending on the purpose of use, but is preferably 0.5 to 200 to facilitate the post-treatment process, particularly for suppressing particle aggregation.
μm is preferable, and 1 to 100 μm is more preferable.

Next, the aqueous medium in the aqueous medium suspension of polymer fine particles thus obtained is replaced with a non-aqueous medium. This substitution is performed by adding a hydrophobizing agent and a non-aqueous medium to an aqueous medium suspension of polymer fine particles, transferring the polymer fine particles into the non-aqueous medium, and then separating the aqueous medium and the non-aqueous medium, This is done by removing the aqueous medium.

In this case, the addition of the hydrophobizing agent and the non-aqueous medium is
The hydrophobizing agent may be added first, followed by the non-aqueous medium, or conversely, the non-aqueous medium may be added first, followed by the hydrophobizing agent, or both may be added simultaneously. However, it is preferable to add the hydrophobizing agent first.

In the present invention, the surface of the polymer fine particles can be hydrophobized by forming an ion complex with a hydrophobizing agent having a charge opposite to the ionic group present on the surface of the polymer fine particles suspended in the aqueous medium. Importantly, in this case, the hydrophobizing agent is preferably a compound having an alkyl group having 12 or more carbon atoms, a perfluoroalkyl group or a polysiloxane group having 4 or more carbon atoms, and an anionic group or a cationic group. is there. In this case, a group represented by the general formula (I) is exemplified as the polysiloxane group.

-[SiR ¹ R ² O]-(I) wherein R ¹ and R ² are the same or different and represent an alkyl group having 1 to 18 carbon atoms or an aryl group having 6 to 30 carbon atoms in total Or an aralkyl group.) As a hydrophobicizing agent having a cationic group, amino-modified polysiloxanes (viscosity of 100 to 1,000,000 mPa · s, functional equivalent of 300
To 100,000 g / mol), alkylamines having 12 or more carbon atoms, perfluoroalkylamines having 4 or more carbon atoms, and the like. Examples of hydrophobizing agents having anionic groups include carboxyl-modified polysiloxanes (viscosity of 100 to 1,000,000 mPa · s, functional group equivalent of 300 to 100,000 g / mol), fatty acids having an alkyl moiety of 12 or more carbon atoms, higher Examples thereof include alcohol sulfates, fatty oil sulfates, alkylarylsulfonic acids, and aliphatic alcohol phosphates.

If the amount of the hydrophobizing agent is too small, it is difficult to form an ion complex, and it is difficult to incorporate particles into the non-aqueous medium. If it is too large, it will be excessively present in the non-aqueous medium. Since there may be a problem in performance, the content is preferably 0.1 to 50% by weight, more preferably 0.5 to 30% by weight, based on the total weight of the monomers A and B.

When a hydrophobizing agent is added to the polymer fine particle dispersion after the completion of the suspension polymerization, an aqueous dispersion of the hydrophobizing agent or an organic solvent having an affinity for water (such as an alcohol having 1 to 3 carbon atoms) may be used. It can be added as a solution or a dispersion. At this time, for the hydrophobizing agent without self-emulsifying property,
An aqueous dispersion may be prepared using a surfactant or the like. For example, for an amino-modified silicone having a high molecular weight and amine equivalent and having no self-emulsifying property, an aqueous dispersion which is forcibly emulsified using a surfactant such as polyoxyethylene alkyl ether may be used.

The non-aqueous medium used in the present invention has a solubility at 25 ° C. of 1 g / 100 g H ₂ O or less, and can be used as long as it does not swell or dissolve the polymer particles.
-Aliphatic hydrocarbon solvents such as butane, n-hexane, n-heptane, n-octane, n-decane, n-dodecane and n-tridecane, and alicyclic hydrocarbon solvents such as cyclopentane, cyclohexane and cycloheptane Etc. are exemplified. Here, the addition amount of the non-aqueous medium is preferably from 60 to 1000% by weight, more preferably from 100 to 500% by weight, based on the weight of the polymer fine particles.

After adding the hydrophobizing agent and the non-aqueous medium to the suspension of the polymer fine particles in the aqueous medium, the mixture is stirred at 30 to 100 ° C. for 30 minutes to 10 hours. Then, after separating and removing the aqueous medium,
The resulting non-aqueous medium dispersion of polymer fine particles can be further subjected to dehydration under reduced pressure, if necessary.

[0022]

According to the present invention, a nonaqueous medium dispersion of surface-hydrophobic polymer fine particles can be easily produced by a simple method without going through complicated steps such as drying / crushing.

[0023]

Example 1 In a 2 L beaker, 574.2 g of ion-exchanged water and 5.8 g of polyvinyl alcohol (GL-03, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) were charged and dissolved and mixed. Next, styrene 75 was used as monomer A.
g, divinylbenzene (Nippon Steel Chemical Co., Ltd., DVB-8
10) 20 g, 5 g of methacrylic acid as monomer B, and 2.4 g of 2,2′-azobis (2,4-dimethylvaleronitrile) (V-65) manufactured by Wako Pure Chemical Industries, Ltd. as a polymerization initiator After dissolving and mixing the solution, the mixture was mixed and then subjected to a dispersion treatment at 10,000 rpm for 5 minutes using a homomixer. This dispersion was placed in a reactor equipped with a thermometer, a cooling pipe, a nitrogen introduction pipe and a stirrer, the temperature was raised to 60 ° C. while introducing nitrogen, and the polymerization reaction was carried out for 12 hours, and the average particle size was 2.3 μm. Of a 15% polymer fine particle aqueous dispersion was obtained. Next, an aqueous solution of an amino-modified silicone (manufactured by Kao Corporation, Kaosilicon,
35 g of TA-02) and 185 g of dodecane were added, reacted at 100 ° C. for 1 hour, cooled and allowed to stand for 30 minutes. After removing the separated aqueous phase, a dehydration operation was performed at 120 ° C. for 1 hour to give a concentration of 35% by weight.
A dodecane dispersion of the hydrophobic polymer fine particles was obtained.

Examples 2 to 4, Comparative Example 1 The same operation as in Example 1 was performed except that the charged amount and the reaction conditions were set to the values shown in Table 1. As a result, in the case of Examples 2 to 4, a dodecane dispersion of hydrophobic polymer fine particles having a polymer fine particle concentration of 35% by weight was obtained. In the case of Comparative Example 1, polymer fine particles did not migrate to the dodecane layer, and a dodecane dispersion of polymer fine particles was not obtained.

[0025]

[Table 1]

Claims (2)

[Claims] 1. A polymerizable monomer having a vinyl group (here, the monomer does not have an ionic group) and a polymerizable monomer having an anionic group or a cationic group. After copolymerization by suspension polymerization in an aqueous medium to obtain polymer fine particles, the surface of the polymer fine particles is formed by forming an ion complex with a hydrophobizing agent having a charge opposite to the ionic group in the polymer. A process for producing a dispersion of polymer fine particles in a non-aqueous medium, which comprises a step of hydrophobizing and a step of replacing an aqueous medium with a non-aqueous medium. 2. The compound according to claim 1, wherein the hydrophobizing agent is a compound having an alkyl group having 12 or more carbon atoms, a perfluoroalkyl group or a polysiloxane group having 4 or more carbon atoms, and an anionic group or a cationic group. Recipe.