JP2547095B2 - Method for producing hydrophilic resin particles - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing hydrophilic resin particles.

[Prior Art] Conventionally, in a reverse phase emulsion polymerization or a reverse phase suspension polymerization, which is one method for obtaining hydrophilic resin particles, an activator such as sorbitan monostearate and a polymer protective colloid such as ethyl cellulose are used. .

[Problems to be Solved by the Invention] However, it is difficult to synthesize relatively large particles with an activator, and it is difficult to synthesize fine particles with a conventional polymer protective colloid. Therefore, even the hydrophilic resin particles having the same composition cannot use the same particle size surface property from the fine particles to the large particles because the dispersant used is different, and the use is limited depending on the particle size.

[Means for Solving the Problems] Then, as a result of intensive research to solve the above problems, the present invention has been achieved. That is, the present invention is a reverse phase emulsion polymerization or a reverse phase suspension polymerization in which an aqueous solution of a hydrophilic monomer is emulsified or suspended in a hydrophobic medium to polymerize the polymer of the monomer represented by the formula [1]. A method for producing hydrophilic resin particles, which comprises solubilizing in a permeable medium and polymerizing, [1] formula (In the formula, R ₁ is H or CH ₃ , R ₂ is a long-chain alkyl group having 5 or more carbon atoms, n is a real number of 2 to 50, and m is a real number of 0 to 20.); The above-mentioned production method is characterized in that the aqueous monomer solution contains a crosslinking agent.

In the formula [1], n is usually a real number of 2 to 50. n
Is less than 2, the dispersion stability during polymerization is poor. m is usually a real number from 0 to 20.

The order of OC ₂ H ₄ and OC ₃ H ₆ does not matter. The connection form may be random, block, or the like, and is not particularly limited.

R ₁ is H or CH ₃ , preferably H. R
The long-chain alkyl group of ₂ may be linear, branched or cyclic, but the number of carbon atoms is preferably 5 or more, more preferably
20 or more. If it is less than 5, the dispersion stability during polymerization is deteriorated.

The method for synthesizing the monomer represented by the formula [1] is not particularly limited, but is usually obtained by an ester reaction of an ethylene oxide and / or propylene oxide adduct of a higher alcohol with (meth) acrylic acid or (meth) acrylic acid chloride. be able to.

In the present invention, a copolymer of the monomer represented by the formula [1] and a copolymer of another monomer copolymerizable with the monomer represented by the formula [1] can be used.

The monomer copolymerizable with the monomer represented by the formula [1] is not particularly limited, and may be a hydrophobic monomer or a nonionic hydrophilic monomer.

Examples of the hydrophobic monomer include styrene, acrylic acid ester, vinyl acetate, ethylene and the like. Examples of the nonionic hydrophilic monomer include hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, (meth) acrylamide, vinylpyrrolidone and the like.

The weight ratio of the monomer represented by the formula [1] and the monomer copolymerizable with the monomer is usually 100/0 to 20/80. If the weight ratio of the monomer represented by the formula [1] is less than 20/80, the dispersion stability of the polymerization becomes poor.

The method for producing the monomer represented by the formula [1] alone and / or the polymer with the monomer copolymerizable therewith is not particularly limited and may be bulk polymerization, solution polymerization, suspension polymerization or the like.

Examples of the hydrophilic monomer used in the present invention include anionic monomers, cationic monomers, nonionic hydrophilic monomers and mixtures thereof.

Any anionic monomer may be used as long as it exhibits anionic properties, but it is preferably one having a carboxyl group and / or a sulfone group.

The anionic monomer having a carboxyl group is an unsaturated mono- or polycarboxylic acid [(meth) acrylic acid (which means acrylic acid and / or methacrylic acid.
The same description is used below. ), Ethacrylic acid, crotonic acid, sorbic acid, maleic acid, itaconic acid, cinnamic acid, etc.], their anhydrides [maleic anhydride, etc.], and their salts [alkali metal salts (sodium, potassium,
Salts such as lithium), alkaline earth metal salts (salts such as calcium and magnesium), ammonium salts and amine salts (salts of alkylamines such as methylamine and trimethylamine; salts of alkanolamines such as triethanolamine and diethanolamine) )] And a mixture of two or more of the above monomers. Among these, preferable are (meth) acrylic acid alkali metal salts.

Examples of the anionic monomer having a sulfonic group include aliphatic or aromatic vinyl sulfonic acids [vinyl sulfonic acid, allyl sulfonic acid, vinyl toluene sulfonic acid, styrene sulfonic acid, etc.], (meth) acrylic sulfonic acid [(meth) acrylic acid Sulfoethyl, sulfopropyl (meth) acrylate, etc., (meth) acrylamidesulfonic acid [2-acrylamido-2-methylpropanesulfonic acid, etc.], and salts thereof [alkali metal salts (salts of sodium, potassium, lithium, etc.)] , Alkaline earth metal salts (salts such as calcium and magnesium), ammonium salts and amine salts (salts of alkylamines such as methylamine and trimethylamine; salts of alkanolamines such as triethanolamine and diethanolamine)] and the above simple salts. Mixtures of two or more bodies and the like. Of these, alkali metal (meth) acrylamidosulfonic acid is preferred.

The cationic monomer may be any one as long as it shows a cationic property, but preferably has a quaternary ammonium salt group.

Examples of the cationic monomer having a quaternary ammonium salt group include a reaction product of a dialkylaminoalkyl (meth) acrylate with an alkyl halide or dialkylsulfate [eg (meth) acryloyloxyethyl trimethylammonium chloride or bromide, (meth) acryloyloxyethyl). Trimethylammonium methosulfate, (meth) acryloyloxyethyl dimethylethylammonium chloride, (meth) acryloyloxyethyl diethylmethylammonium chloride, (meth) acryloyloxyethyl dimethylbenzylammonium chloride, (meth) acryloyloxypropyl trimethylammonium chloride,
(Meth) acryloyloxypropyltrimethylammonium methosulfate, etc.]; Reaction product of dialkylaminohydroxyalkyl (meth) acrylate and alkyl halide or dialkylsulfate [eg (meth)
Acryloyloxyhydroxyethyltrimethylammonium chloride or bromide, (meth) acryloyloxyhydroxyethyltrimethylammonium methosulfate, (meth) acryloyloxyhydroxypropyltrimethylammonium chloride, etc.];
Reaction products of dialkylaminoalkyl (meth) acrylamides with alkyl halides or dialkylsulfates [eg chloride or bromide of trimethylaminoethyl (meth) acrylamide, chloride of trimethylaminopropyl (meth) acrylamide, diethylmethylaminopropyl (meth)] Acrylamide chloride, etc.]; Reaction product of dialkylaminohydroxyalkyl (meth) acrylamide with alkyl halide or dialkylsulfuric acid [eg trimethylaminohydroxyethyl (meth)]
Acrylamide chloride, trimethylaminohydroxypropyl (meth) acrylamide chloride, diethylmethylaminohydroxypropyl (meth) acrylamide chloride, etc.]; N-alkylvinylpyridinium halides [eg N-methyl-2-vinylpyridinium chloride or Examples thereof include bromide, N-methyl-4-vinylpyridinium chloride, etc.], trialkylallylammonium halide [eg, trimethylallylammonium chloride or bromide, triethylallylammonium chloride], and mixtures of two or more thereof. Preferred among these are reactants of a dialkylamino (meth) acrylate with an alkyl halide.

Examples of the nonionic hydrophilic monomer include the same as those described in the section of the polymer of the monomer represented by the formula [1].

The weight ratio of the hydrophilic monomer to the homopolymer of the monomer represented by the formula [1] and / or the copolymer of the monomer copolymerizable therewith and the hydrophilic monomer is usually 1/99 to 80/20. Ratio is 1/99
If it is smaller, the polymerization stability becomes worse. If the ratio is more than 80/20, the dispersion stability is not improved.

In the present invention, it is possible to produce either a water-soluble polymer or a water-absorbing cross-linked polymer hydrophilic resin.

In order to obtain a crosslinked polymer, a method of using a peroxide as a polymerization initiator to cause self-crosslinking during polymerization, a method of using a crosslinking agent, and the like can be mentioned.

The cross-linking agent used in the present invention includes a compound (1) having at least two polymerizable double bonds and a cationic vinyl monomer and / or anionic vinyl monomer having at least one polymerizable double bond. Examples thereof include compound (2) having at least one group capable of reacting with a functional group of a monomer.

 Examples of the compound (1) include the following.

Bis (meth) acrylamide: N, N-alkylene (C ₁ ~
C ₆₎ bis (meth) acrylamides (e.g. N, N-methylenebisacrylamide).

Di- or polyester of polyols and unsaturated mono- or polycarboxylic acids: Di- or tri- (meth) acrylic acid of polyols [ethylene glycol, trimethylolpropane, glycerin, polyoxyethylene glycol, polyoxypropylene glycol, etc.] Esters: unsaturated polyesters [obtained by reaction of the above polyols with unsaturated acids such as maleic acid] and di- or tri- (meth) acrylic acid esters [obtained by reaction of polyepoxides with (meth) acrylic acid] "Such.

Carbamyl ester: polyisocyanate [tolylene diisocyanate, hexamethylene diisocyanate,
Carbamyl ester obtained by reacting 4,4'-diphenylmethane diisocyanate and NCO group-containing prepolymer (obtained by reaction of the above polyisocyanate with active hydrogen atom-containing compound) and hydroxyethyl (meth) acrylate .

Di or polyvinyl compounds: divinyl benzene, divinyl toluene, divinyl xylene, divinyl ether,
Divinyl ketone, trivinyl benzene, etc.

Di- or poly- (meth) allyl ethers of polyols: Di- or poly- (meth) allyl ethers of polyols [alkylene glycols, glycerin, polyalkylene glycols, polyalkylene polyols, carbohydrates etc.] such as polyethylene glycol diallyl ether and Allylated starch, allylated cellulose.

Di- or poly-allyl esters of polycarboxylic acids:
Diallyl phthalate, diallyl adipate and the like.

Esters of unsaturated mono- or polycarboxylic acids with mono (meth) allyl ethers of polyols: (meth) acrylates of polyethylene glycol monoallyl ether and the like.

Polyallyloxyalkanes: tetraallyloxyethane and the like.

Examples of the compound (2) include ethylenically unsaturated compounds containing a group reactive with a carboxyl group, a sulfone group and / or a quaternary ammonium salt group such as a hydroxyl group, an epoxy group and a tertiary amine group. Specifically, a hydroxyl group-containing unsaturated compound [N-methyl roll (meth) acrylamide, etc.] and an epoxy group-containing unsaturated compound [glycidyl (meth) acrylate, etc.] and a tertiary amino group-containing unsaturated compound [(meth)
Dimethylaminoethyl acrylate, diethylaminoethyl (meth) acrylate, etc.] and the like.

Among these crosslinking agents, the compound (1) is preferable, and N, N-methylenebisacrylamide, ethylene glycol diacrylate, trimethylolpropane triacrylate and tetraallyloxyethane are particularly preferable.

The amount of the cross-linking agent is usually 0.01 to 10% by weight, preferably 0.1 to 5% by weight, based on the total weight of the monomer represented by [1] and the hydrophilic monomer.

As a polymer composed of these monomers,
Examples thereof include a monomer represented by the formula [1] and a sodium acrylate crosslinked polymer, and a monomer represented by the formula [1] and a poly-2-acrylamido-2-methylpropanoic acid crosslinked polymer.

As the polymerization method, reverse phase emulsion polymerization and reverse phase suspension polymerization are preferable.

Usually, the polymerization catalyst used for reverse phase emulsion polymerization is oil-soluble, and the polymerization catalyst used for reverse phase suspension polymerization is water-soluble.

Examples of the oil-soluble polymerization catalyst include azo-based catalysts such as azobisisobutyronitrile and organic peroxide-based catalysts such as isobutyl peroxide.

As the water-soluble polymerization catalyst, an azo catalyst such as azobisamidinopropane dihydrochloride, an organic peroxidation catalyst such as t-butylpermaleic acid, an inorganic peroxidation catalyst such as potassium persulfate, and a redox catalyst Can be given.

As the hydrophobic medium used in the reverse phase emulsion polymerization and the reverse phase suspension polymerization, a polymer of the monomer represented by the formula [1] and / or a copolymer with a monomer copolymerizable therewith can be solubilized. Any hydrophobic hydrocarbon such as aliphatic hydrocarbons, alicyclic hydrocarbons, halogenated hydrocarbons, aromatic hydrocarbons and mineral oils can be used.

Of these, preferred are aliphatic hydrocarbons and alicyclic hydrocarbons.

Dehydration of the water-containing resin after the polymerization and separation from the hydrophobic medium may be carried out by a conventional method. That is, dehydration by azeotropic distillation in a hydrophobic medium in an emulsified or dispersed state, separation by centrifugation or filtration, separation of particles from the hydrophobic medium and dehydration drying with hot air or reduced pressure, or spray drying. , Freeze-drying method and the like.

[Examples] Hereinafter, the method for producing the hydrophilic resin particles of the present invention will be further described with reference to Examples, but the present invention is not limited thereto. In the following, "part" means "part by weight". The evaluation method was as follows.

<Amount of Adhesion> The dispersion stability of polymerization was evaluated by the weight% of the polymer adhering to the reactor or the agglomerated polymer with respect to the charged monomers.

<Water Absorption> The water absorption of the resin obtained by the reverse phase suspension polymerization method was evaluated by the following method.

0.1 g of resin was placed in a 250-mesh nylon bag, immersed in a large amount of ion-exchanged water for 1 hour, then drained for 15 minutes, and the amount of water absorption was defined as 10 times the weight increase.

The water absorption of the resin obtained by the reverse phase emulsion polymerization method was evaluated by the following method.

0.1 g of the resin was placed in a 100 ml beaker and allowed to absorb ion-exchanged water for 1 hour. The aqueous dispersion solution of hydrated fine particle gel was separated into a lower gel layer and a surplus water layer by a centrifuge, and the amount of water absorption was 10 times the amount of the gel layer.

<Viscosity> The viscosity increase of the uncrosslinked hydrophilic polymer was evaluated by the viscosity in an aqueous solution at a polymer concentration of 1.0% by weight and a temperature of 30 ° C.

Example 1 [Reverse Phase Emulsion Polymerization of Anionic Resin] Synthesized by esterification reaction of an ethylene oxide adduct of a higher alcohol with acrylic acid, In the formula [1], R ₁ is H, n is 20, m is 0, and R ₂ is carbon number.
20 parts of the linear alkyl group monomer (A) of 20 was dissolved in 20 parts of cyclohexane, and polymerization was carried out in a nitrogen atmosphere at 50 ° C. with 0.01 part of azobisisobutyronitrile as a catalyst to obtain a polymerization rate.
A polymer (B) solution of 99% or more was obtained.

6 parts of the obtained polymer (B) solution and cyclohexane
30 parts was placed in a stirrable reaction vessel, and nitrogen substitution was carried out at 50 ° C. for 1 hour. With stirring, sodium acrylate containing methylenebisacrylamide (0.2% relative to acrylic acid) (74 mol%
Neutralization) Of 16 parts of 45% aqueous solution, 4 parts were put into a reaction vessel, and 0.001 part of azobisisobutyronitrile was added. After 30 minutes, the rest of the aqueous sodium acrylate solution was added dropwise over 1.5 hours, and the mixture was aged at 60 ° C for 1 hour. It was dehydrated azeotropically at 70 to 80 ° C. to obtain an emulsion in which a sodium acrylate cross-linked polymer was dispersed (average particle diameter: 0.2 μ). 35 emulsion
When filtered through a 0-mesh wire net, there were no resin particles aggregated in the residue, and almost no resin particles adhered to the reaction vessel. The filtered emulsion was separated from the solvent and the resin by using an ultracentrifuge, and the aggregated resin was re-ground by using a jet mill to obtain the hydrophilic resin particles of the present invention.

Table 1 shows the amount of resin adhering to the reaction vessel and the amount of water absorption of the resin during polymerization.

Example 2 [Reverse Phase Emulsion Polymerization of Cationic Resin] Instead of 16 parts of a 45% aqueous solution of methylenebisacrylamide-containing Na acrylate (74 mol% neutralized) in Example 1, methylenebisacrylamide-containing (to 0.1% of monomer).
%) Acryloyloxyethyltrimethylammonium chloride 60% aqueous solution was used in the same manner as above to obtain an emulsion in which the cationic crosslinked polymer was dispersed (average particle size: 1.3 μ). During the polymerization, there were no resin particles aggregated and almost no resin particles adhered to the reaction vessel. Post-treatment was carried out in the same manner as in Example 1 to obtain the hydrophilic resin particles of the present invention.

Table 1 shows the amount of resin adhering to the reaction vessel and the amount of water absorption of the resin during polymerization.

Example 3 [Reverse Phase Emulsion Polymerization of Amphoteric Resin] In Example 1, instead of 16 parts of a 45% aqueous sodium acrylate (74 mol% neutralized) 45% methylenebisacrylamide-containing solution, a methylenebisacrylamide-containing (pair of monomer 0.2
%) Acryloyloxyethyl trimethyl ammonium chloride and acrylic acid mixture (molar ratio 1: 1) 60%
Polymerization was performed in the same manner except that 16 parts of the aqueous solution was used to obtain an emulsion in which the amphoteric crosslinked polymer was dispersed (average particle size: 0.8
μ). During the polymerization, there were no resin particles aggregated and almost no resin particles adhered to the reaction vessel. Post-treatment was carried out in the same manner as in Example 1 to obtain the hydrophilic resin particles of the present invention.

Table 1 shows the amount of resin adhering to the reaction vessel and the amount of water absorption of the resin during polymerization.

Example 4 [Reverse Phase Suspension Polymerization of Anionic Resin] Synthesized by esterification reaction of an adduct of ethylene oxide and propylene oxide of a higher alcohol with acrylic acid, In the formula [1], R ₁ is H, n is 25, m is 1 and R ₂ is carbon number.
20 parts of a linear alkyl group monomer (C) and 2 parts of methyl methacrylate are dissolved in 20 parts of cyclohexane and polymerized by polymerizing 0.01 part of azobisisobutyronitrile at 50 ° C. in a nitrogen atmosphere as a catalyst. A polymer (D) solution having a rate of 99% or more was obtained.

5 parts of the obtained polymer (D) solution and cyclohexane
30 parts was put into a stirrable reaction vessel, dissolved at 50 ° C., and purged with nitrogen for 1 hour. Under stirring, 16 parts of 45% aqueous solution of sodium acrylate (74 mol% neutralized) containing methylenebisacrylamide (0.2% of acrylic acid) mixed with 0.05% ammonium persulfate as an aqueous polymerization catalyst, 4
Parts were placed in a reaction vessel. After 30 minutes, the rest of the aqueous sodium acrylate solution was added dropwise over 1.5 hours, and the mixture was aged at 60 ° C for 1 hour. Dehydrated azeotropically at 70-80 ° C, Na acrylate
A solution in which the system cross-linked polymer was dispersed was obtained. This was filtered through a 350 mesh wire mesh. The filtration residue was spread on a Teflon plate and dried to obtain the hydrophilic resin particles of the present invention having an average particle size of 80μ. There were no agglomerated resin particles and almost no resin particles adhered to the reaction vessel.

Table 1 shows the amount of resin adhering to the reaction vessel and the amount of water absorption of the resin during polymerization.

Example 5 [Reverse Phase Emulsion Polymerization of Anionic Resin] Synthesized by an esterification reaction of an ethylene oxide adduct of a higher alcohol with acrylic acid, In the formula [1], R ₁ is H, n is 30, m is 0, and R ₂ is carbon number.
19 parts of 16 linear alkyl group monomers (E) and 1 part of vinyl acetate were dissolved in 20 parts of cyclohexane, and the solution was placed in a nitrogen atmosphere.
Polymerization was carried out at 50 ° C. with 0.01 part of azobisisobutyronitrile as a catalyst to obtain a polymer (F) solution having a polymerization rate of 99% or more.

5 parts of the obtained polymer (F) solution and cyclohexane
30 parts of the reaction mixture was placed in a stirrable reaction vessel, the monomer (D) was dissolved at 50 ° C., and the atmosphere was replaced with nitrogen for 1 hour. Under stirring, sodium acrylate (74 mol% neutralized) containing no cross-linking agent 45
% 16% aqueous solution, 4 parts were put in a reaction vessel, and 0.001 part of azobisisobutyronitrile was added. After 30 minutes, the rest of the aqueous sodium acrylate solution was added dropwise over 1.5 hours, and the mixture was aged at 60 ° C for 1 hour. At 70-80 ° C, dehydrate by azeotropic distillation,
An emulsion in which a sodium acrylate polymer was dispersed was obtained (average particle size: 0.1 μ). When the emulsion was filtered through a wire mesh of 350 mesh, there were no resin particles aggregated in the residue, and almost no resin particles adhered to the reaction vessel.
The filtered emulsion was separated from the solvent and the resin by using an ultracentrifuge, and the aggregated resin was re-ground by using a jet mill to obtain the hydrophilic resin particles of the present invention.

Table 1 shows the amount of resin adhering to the reaction vessel during polymerization and the viscosity of the resin in aqueous solution.

Comparative Example 1 [Reverse Phase Emulsion Polymerization of Anionic Resin] In Example 1, instead of 3 parts of the monomer (A),
Synthesized by esterification reaction of ethylene oxide adduct of aliphatic alcohol and acrylic acid, In the formula [1], R ₁ was H, n was 1, m was 0, and R ₂ was a similar polymer except that a linear alkyl group having 2 carbon atoms was used. During the polymerization, the resin particles aggregated and the dispersion stability was poor. In addition, the amount of adhesion to the reaction container was large.

Comparative Example 2 [Reverse Phase Emulsion Polymerization of Anionic Resin] In Example 1, instead of 3 parts of the monomer (A),
Polymerization was conducted in the same manner except that 3 parts of hydroxyethyl cellulose was used. During the polymerization, the dispersion stability was good, but it did not emulsify,
When the stirring was stopped after the polymerization, the particles were settled. In addition, the amount attached to the reaction vessel was also considerably large.

The resin particle dispersion was filtered through a 350-mesh wire net. When the filtration residue was spread on a Teflon plate and dried, the average particle size of the obtained resin was 120μ.

Table 1 shows the amount of resin adhering to the reaction vessel during polymerization and the viscosity of the resin in aqueous solution.

[Effects of the Invention] The present invention is capable of producing a hydrophilic resin from fine particles to large particles by using only a polymeric protective colloid having a similar composition. In the reverse phase emulsion polymerization, the conventional activator is not required. Therefore, the hydrophilic resin particle emulsion obtained by reverse phase emulsion polymerization is a dispersion system containing no activator, and can be applied to limited applications (eg, paints, pharmaceutical materials, etc.) that have been adversely affected by activators. It is possible.

Since the monomer represented by the formula [1] has both a hydrophilic segment and a lipophilic segment, it is considered that the polymer forms a stable monomer micelle phase during polymerization. Therefore, in the polymer of the monomer represented by the formula [1] used as the protective colloid, the hydrophilic segment and the hydrophobic segment can be easily controlled by synthesis,
The particle size can be easily controlled based on this segment balance, and a resin having an arbitrary particle size can be obtained.

Claims (6)

(57) [Claims] 1. In a reverse phase emulsion polymerization or a reverse phase suspension polymerization in which an aqueous solution of a hydrophilic monomer is emulsified or suspended in a hydrophobic medium to polymerize, a polymer of the monomer represented by the formula [1] is made hydrophobic. A method for producing hydrophilic resin particles, which comprises solubilizing in a medium and polymerizing. [1] Expression (In the formula, R ₁ is H or CH ₃ , R ₂ is a long-chain alkyl group having 5 or more carbon atoms, n is a real number of 2 to 50, and m is a real number of 0 to 20.) 2. The method according to claim 1, wherein the hydrophobic medium is an aliphatic hydrocarbon or an alicyclic hydrocarbon. 3. The method according to claim 1, wherein the hydrophilic monomer is one kind or a mixture of two or more kinds selected from the group consisting of anionic monomer, cationic monomer and nonionic hydrophilic monomer. 4. The method according to claim 1, wherein the alkyl group of R ₂ has 20 or more carbon atoms. 5. The production method according to claim 1, wherein R ₁ is H. 6. The method according to claim 1, wherein the aqueous hydrophilic monomer solution contains a crosslinking agent.