JPH01167304A - Production of polymer granules - Google Patents

Abstract

PURPOSE:To obtain in high efficiency polymer granules of narrow granular size distribution along with stably retaining the polymerization system, by inverse phase suspension polymerization of a water-soluble ethylenic unsaturated monomer using, as the dispersant, a combination of a specific oil-soluble cationic copolymer and nonionic surfactant. CONSTITUTION:Using as the dispersant, a combination of (A) an oil-soluble cationic copolymer obtained by copolymerization between 70-99.5mol% of a lipophilic ethylenic unsaturated monomer (e.g., styrene, alkyl-substituted styrene) and 0.5-30wt.% of a second ethylenic unsaturated monomer having quaternary ammonium group [e.g., dialkylaminoalkyl(meth)acrylate quaternary salt] and (B) a nonionic surfactant (e.g., sucrose fatty acid ester, sorbitan fatty acid ester), a water-soluble ethylenic unsaturated monomer is put to inverse phase suspension polymerization in a hydrophobic solvent. Preferably, the amount of the component A to be used is 0.1-10wt.% based on the water-soluble ethylenic unsaturated monomer, whereas for the component B, 0.05-5wt.%.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention involves adding an aqueous solution of a water-soluble ethylenically unsaturated monomer to a polymerization inert and hydrophobic solvent to perform reverse phase suspension polymerization. It relates to a method for producing cohesive particles, and more specifically, by using a specific combination of dispersants, it is possible to maintain the polymerization system stably and to efficiently produce polymer particles with a narrow particle size distribution. The present invention relates to a method for producing polymer particles by reverse-phase suspension polymerization, which can be easily produced.

The present invention has conventionally been obtained by a reversed-phase suspension polymerization method,
It can be suitably used in the production of super absorbent resins, thickeners, flocculants, etc.

[Conventional technology]

Method 1 of polymerizing water-soluble ethylenically unsaturated monomers
The so-called reversed-phase suspension polymerization method, in which an aqueous monomer solution is polymerized by suspending or dispersing it in a hydrophobic solvent, is well known. It is important to accurately select a dispersant that can stably disperse an aqueous solution in a hydrophobic solvent and then prevent or reduce agglomeration of the resulting polymer particles.

In other words, by selecting a suitable dispersant, productivity can be significantly improved and polymer particles with uniform physical properties can be obtained.

Dispersants conventionally used in the reverse phase suspension polymerization of water-soluble ethylenically unsaturated monomers include, for example, sorbitan monostearate, sorbitan monooleate, ethoxylated fatty acid amides, and glycerin. Nonionic surfactants such as fatty acid esters are known (Japanese Patent Publication No. 54-30710, etc.).

In addition to the above, polymer compounds such as allyl group-containing resins treated with maleic anhydride, polymers containing carboxyl groups that have affinity for organic solvents, and lipophilic cellulose derivatives may also be used. Known (Unexamined Japanese Patent Publication No. 57-7
Publication No. 4309, etc.).

[Problem that the invention seeks to solve]

However, when nonionic surfactants from the former group are used as dispersants, the resulting polymer becomes fine particles, causing problems such as generation of dust during the separation and drying process, and handling thereof. may be difficult. If the latter group of polymer compounds is used as a dispersant, the resulting polymer will be in the form of small granules, which can improve the above-mentioned drawbacks, but during the polymerization operation, the polymer particles may It tends to stick to tank walls, stirrers, etc., and a considerable portion of the reacted monomer may be lost as unusable deposits in the polymerization tank. Generally, it takes a great deal of effort to remove water-soluble ethylenically unsaturated monomer deposits from a polymerization tank, which hinders efficient production of particulate polymers.

[Means for solving problems]

The present inventors have solved the above-mentioned problems of the prior art (as a result of intensive research), it has been found that lipophilic ethylenically unsaturated monomer units and cationic group-containing ethylenically unsaturated monomer units are essential. It was discovered that a polymer having a constituent component of is useful as a dispersant in this technical field, and
It was disclosed in JP-A-157505.

As a result of further studies, the stability during polymerization was further increased by using the oil-soluble cationic copolymer together with a nonionic surfactant, and the particle size distribution of the resulting small granular polymer was improved. It was discovered that the distance becomes narrower, leading to the present invention.

That is, in the present invention, when carrying out reverse phase suspension polymerization of a water-soluble ethylenically unsaturated monomer in a hydrophobic solvent, 70 to 99.5 mol% of a lipophilic ethylenically unsaturated monomer and 4 Ethylenically unsaturated monomer having grade ammonium group 0.5~
A method for producing polymer particles, characterized by using an oil-soluble cationic copolymer (8) obtained by copolymerizing 30 mol% with a nonionic surfactant (B) as a dispersant. It provides:

Examples of the lipophilic ethylenically unsaturated monomer that is a component of the oil-soluble cationic copolymer (A) in the present invention include styrene, alkyl-substituted styrene (alkyl group has 1 to 18 carbon atoms), ( meth)acrylic acid alkyl ester (alkyl group has 1 to 18 carbon atoms), fatty acid ester of vinyl alcohol (fatty acid has 2 to 1B carbon atoms), N-alkyl (meth)acrylamide (alkyl group has 1 to 18 carbon atoms), etc. can be exemplified. These can be used alone or in combination of two or more.

Furthermore, as the other constituent component of the oil-soluble cationic copolymer (A), the ethylenically unsaturated monomer having a quaternary ammonium group, for example, a quaternary ammonium group represented by the formula - , vinyl group, (meta)
Examples include monomers having an ethylenically unsaturated group such as an acryloyl group, and these may be used alone, or two types may be used.
A mixture of more than one species may be used.

These ethylenically unsaturated monomers having a quaternary ammonium group are generally obtained by quaternizing the corresponding ethylenically unsaturated monomer having a tertiary amino group using a suitable quaternizing agent. .

Examples of the ethylenically unsaturated monomer having a tertiary amino group used here include dimethylaminomethyl acrylate, dimethylaminoethyl acrylate, dimethylaminopropyl acrylate, diethylaminomethyl acrylate, diethylaminoethyl acrylate, diethylaminopropyl acrylate, and Corresponding methacrylates; dimethylaminomethylacrylamide, dimethylaminoethyl acrylamide, dimethylaminopropylacrylamide, diethylaminomethylacrylamide, diethylaminoethyl acrylamide, diethylaminopropylacrylamide, and their corresponding methacrylamide; vinylpyridine, 2-methyl-4
- Vinylpyridines such as vinylpyridine and 2-methyl-5-vinylpyridine; Styrenes having a dialkylamino group such as N,N-dimethylaminostyrene and N,N-dimethylaminomethylstyrene; 2-dimethylaminoethyl vinyl ether Examples include vinyl ethers having a dialkylamino group such as.

Examples of quaternizing agents include alkyl halides such as methyl chloride, methyl bromide, methyl iodide, ethyl chloride, ethyl bromide, propyl bromide, butyl bromide, and octyl bromide, and sulfuric acids such as dimethyl sulfate and diemyl sulfate. Examples include alkyl esters.

In addition to these methods using a quaternizing agent, the monomer having a tertiary amino group as described above is converted into an acid salt such as hydrochloric acid or acetic acid, and then an alkylene oxide such as ethylene oxide or propylene oxide is used. A method of quaternizing by reacting can also be used.

The oil-soluble cationic copolymer (8) in the present invention can be obtained by copolymerizing a lipophilic monomer such as styrene with a heptamer having a tertiary amino group, and then quaternizing the copolymer with a quaternizing agent. Although it is possible to produce the quaternizing agent, it is necessary to use an excessive amount of the quaternizing agent to complete the quaternizing process, and the post-treatment of the excess quaternizing agent is complicated. A method of copolymerizing class salt monomers is preferred.

For copolymerization, a method of radical polymerization using an azo or peroxide initiator in the presence of a solvent capable of dissolving each of the constituent monomers and the resulting copolymer is appropriately used.

When using the thus obtained oil-soluble cationic copolymer as a dispersant in reverse-phase suspension polymerization, the balance between hydrophilicity and lipophilicity is important from the viewpoint of solubility in the solvent and dispersion performance during suspension polymerization. It becomes a factor.

These factors can be controlled by the type and content of each constituent monomer described above, and are selected to be compatible with the water-soluble ethylenically unsaturated monomer and solvent used for polymerization.

In the present invention, the amounts of the lipophilic ethylenically unsaturated monomer and the ethylenically unsaturated monomer having a quaternary ammonium group constituting the oil-soluble cationic copolymer (8) are as follows:
70-99.5 mol% and 0.5-30 mol%, respectively
It is. More preferably, the content of the ethylenically unsaturated monomer having a quaternary ammonium group is 1 to 15 mol%.

If the content of the ethylenically unsaturated monomer having a quaternary ammonium group exceeds 30 mol%, the solubility in the oily solvent used as the dispersion medium will be poor and the dispersion stability will be poor due to the bias toward the hydrophilic side. That's why I don't like it.

Further, the molecular weight of the oil-soluble cationic copolymer (A) in the present invention is preferably a number average molecular weight of 500 to 500,000. If the number average molecular weight is less than 500 or more than 500,000, a sufficient dispersion stabilizing effect will not be exhibited even if the balance between hydrophilicity and lipophilicity is achieved.

The oil-soluble cationic copolymer (A) in the present invention is a copolymer of the above lipophilic ethylenically unsaturated monomer and an ethylenically unsaturated monomer having a quaternary ammonium group. There are various combinations of the two, but among them, styrene or α-methylstyrene,
A copolymer of an alkyl-substituted styrene such as vinyltoluene and a dialkylaminoalkyl (meth)acrylate quaternary salt or a dialkylaminoalkyl (meth)acrylamide quaternary salt is preferred).

In the present invention, the above oil-soluble cationic copolymer (A
) Examples of the nonionic surfactant (B) in combination with sucrose fatty acid ester, sorbitan fatty acid ester, glycerin fatty acid ester, polyoxyethylene alkyl ether, polyoxyethylene alkylphenol ether, etc., and only one of these can be used. It can be used alone or in combination of two or more kinds.

These nonionic surfactants (B) are appropriately selected and used depending on the chemical structure and HLB depending on the water-soluble ethylenically unsaturated monomer and solvent used for polymerization, but among the above, Sucrose fatty acid esters and sorbitan fatty acid esters are preferred, and particularly preferred are sucrose fatty acid esters with an HLB of 2 to 15, or sorbitan fatty acid esters with an IILB of 4 to 8.

In the present invention, when a water-soluble ethylenically unsaturated monomer is subjected to reverse phase suspension polymerization in a hydrophobic solvent, the above-mentioned oil-soluble cationic copolymer (^) and a nonionic surfactant ( B
) is used in combination as a dispersant, and the appropriate amount of the oil-soluble cationic copolymer (A) to be added is based on the water-soluble ethylenically unsaturated monomer. Usually 0.1 to IO% by weight, preferably 0.5 to 5% by weight
It is. Further, the appropriate amount of nonionic surfactant (B) to be added is usually 0.05 to 5% by weight, preferably 0.1 to 3% by weight based on the water-soluble ethylenically unsaturated monomer. be.

Further, the weight ratio of the added amounts of the oil-soluble cationic copolymer (A) and the nonionic surfactant (B) can be appropriately selected within the above range, but preferably (A
) / (B) = 50/1 to l/10, more preferably (^)/(B) = 20/1 to 11
The range is 5.

If the amount of the oil-soluble cationic copolymer (A) and/or nonionic surfactant (B) is outside the above range,
Polymerization stability deteriorates, and particle aggregation and agglomeration occur, which is undesirable. Furthermore, if the amount is too large, no improvement in dispersion performance will be observed, and the particles may become more likely to aggregate.

Furthermore, if the ratio of the oil-soluble cationic copolymer (8) and the nonionic surfactant (B) is out of the above range, the characteristic of narrow particle size distribution of the resulting polymer particles is lost. Put it away.

Using a dispersant consisting of a combination of the oil-soluble cationic copolymer (^) and a nonionic surfactant (B) described above, a water-soluble ethylenically unsaturated monomer is added to a hydrophobic solvent. An aqueous solution of is dispersed together with a water-soluble radical polymerization initiator to perform polymerization.

In principle, any hydrophobic solvent can be suitably used as long as it is inactive for polymerization and does not dissolve water. Considering the removal of polymerization heat and the drying process of the obtained polymer, aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons, or a mixed solvent thereof having a boiling point of 30 to 200°C are preferable, especially n -hexane,
Cyclohexane, benzene, toluene, or a mixed solvent thereof is preferably used.

Various types of water-soluble ethylenically unsaturated monomers can be mentioned. For example, alkali metal salts, ammonium salts, amine salts of acrylic acid or methacrylic acid,
Examples include acrylamide or methacrylamide, water-soluble N-substituted acrylamide or methacrylamide, vinylpyrrolidone, sulfonated styrene, alkali metal salts such as vinylsulfonic acid, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, and the like. These monomers can be used in any combination of one or more types. Further, other oil-soluble monomers can be copolymerized within a range that does not impair hydrophilicity.

Furthermore, if necessary, a water-soluble crosslinking agent having two or more polymerizable unsaturated groups, such as methylene bisacrylamide, or two or more polymerizable unsaturated groups capable of reacting with the functional group of the ethylenically unsaturated monomer may be added. It is also possible to carry out a crosslinking reaction during or after the (co)polymerization of the monomers using a water-soluble crosslinking agent having a functional group, such as ethylene glycol diglycidyl ether.

Although the monomer concentration of the aqueous monomer solution can be varied within a wide range, it is preferably 15 to 80% by weight for boat fishing.

Further, the ratio between the amount of the monomer aqueous solution and the amount of the polymerization-inactive and hydrophobic solvent can be varied over a wide range, but usually the volume ratio is 1=1 to 1:4. A range of is suitable.

Examples of water-soluble radical polymerization initiators include peroxides,
Hydroperoxide, an azo compound, etc. are used in a conventional manner. It is also possible to use a mixture of two or more of these polymerization initiators, and it is also possible to use them as a redox polymerization initiator by adding chromium ions, sulfites, hydroxylamine, hydrazine, etc. It is.

〔Example〕

The present invention will be specifically explained below with reference to Synthesis Examples, Examples, and Comparative Examples, but the present invention is not limited to these Examples.

Synthesis Example-1 104.2 g of styrene was placed in a 300@Z fourth flask equipped with a stirrer, thermometer, reflux condenser, and nitrogen gas inlet tube.
(1.0 mol), methacryloylethyltrimethylammonium chloride 6.4 g (0.03 mol), toluene 11.9 g, isopropyl alcohol (IP
A) After adding and mixing 27.6 g, 3 g of 2.2”-azobisisobutyronitrile (hereinafter abbreviated as AIBN),
Sufficient nitrogen gas replacement was performed. After raising the temperature to 80°C, polymerization was carried out at 80'C for 8 hours. After diluting with toluene, the polymer solution was precipitated from a two-layer n-hexane/water solvent system, filtered and dried to obtain 93.2 g of oil-soluble cationic copolymer-8.

The nitrogen content of this material is 0.60%, and from this value 4
The content of class salt monomer units is 4.7 mol%. Further, the number average molecular weight by GPC was 30,000 (in terms of polystyrene).

Synthesis Example-2 Styrene 104.2 g (1.0 mol), methacryloylethyltrimethylammonium methosulfate 14.9 g (0.05 mol), acetonitrile 29.
Polymerization and polymer isolation were carried out in the same manner as in Synthesis Example 1 using 8g of 8IBN and 1.3g of 8IBN.

97.2 g of oil-soluble cationic copolymer-B was obtained,
This product had a nitrogen content of 0.76% and contained 6.3 mol% of quaternary salt monomer units. Further, the number average molecular weight by GPC was 34.000 (in terms of polystyrene).

Example-1 127.5 g of 80% acrylic acid aqueous solution was weighed into a 500 liter fourth flask, and while stirring under cooling, 30
% caustic soda aqueous solution was added dropwise to neutralize the mixture.

Next, add 0.23 g of potassium persulfate to 7.0 g of ion-exchanged water.
5 g of the solution was added and mixed, and dissolved oxygen was removed by nitrogen gas blowing to prepare a monomer/initiator aqueous solution.

In a 1F fourth flask equipped with a stirrer, a thermometer, a reflux condenser, a dropping funnel, and a nitrogen gas introduction tube, add cyclohexane 400- and the oil-soluble cationic copolymer-A obtained in Synthesis Example-1 1.25 g, and Rheodol 5p-plo
(Sorbitan monopalmitate, Kao ■) 0.50
The temperature was raised to 75°C while blowing nitrogen gas to drive out dissolved oxygen. Next, the monomer/initiator aqueous solution was mixed with cyclohexane under refluxing conditions for 3
Dropped in 30 minutes while stirring at 50 rpm,
Thereafter, polymerization was carried out under reflux conditions for 3 hours. After the polymerization, the produced polymer was filtered and dried under reduced pressure at 80"C to 100°C to obtain 88.0 g of granular sodium polyacrylate. .

The median particle size of the obtained polymer was 300 ts, and the 25% diameter and 75% diameter were each 230.370 n.

In addition, almost no deposits were observed in the tank.

Examples-2 to 5 Oil-soluble cationic copolymer-^ obtained in Synthesis Example-1 as an oil-soluble cationic copolymer, or Oil-soluble cationic copolymer-B obtained in Synthesis Example-2 and Rheodol 5P-LIO (, sorbitan monolaurate) as a nonionic surfactant.

(manufactured by Kao ■), Sugar Ester 5770.51570 (
Sig sugar fatty acid ester, manufactured by Mitsubishi Kasei Foods ■), Rheodol^015 (sorbitan sesquioleate.

Polymerization was carried out in the same manner as in Example 1, except that a polymer (manufactured by Kao Corporation) was used.

The yield of the obtained sodium polyacrylate and the particle size of the particles are shown in Table I.

In either case, almost no deposits were observed in the tank.

Table-1 Example-6 Other than using 1.0 g of the oil-soluble cationic copolymer-B obtained in Synthesis Example-2 as the oil-soluble cationic copolymer and 57701.0 g of sugar ester as the nonionic surfactant. Polymerization was carried out in the same manner as in Example-1.

The yield and particle size of the obtained sodium polyacrylate are shown in Table 2. In addition, almost no deposits were observed in the tank.

Example-7 Example except that 82.5 g of the oil-soluble cationic copolymer obtained in Synthesis Example-2 was used as the oil-soluble cationic copolymer, and 57700.5 g of sugar ester was used as the nonionic surfactant. Polymerization was carried out in the same manner as in -1.

The yield and particle size of the obtained sodium polyacrylate are shown in Table 2. In addition, almost no deposits were observed in the tank.

Table 2 Comparative Example 1 Styrene-dimethylaminoethyl methacrylate copolymer (dimethylaminoethyl methacrylate 4.
The same operation as in Example 1 was carried out except that 25 g of 5 mol % content, number average molecular weight 28,000 N, and 25 g were used.

During the dropwise addition of the monomer/initiator aqueous solution, the generated sodium polyacrylate became lumpy and became impossible to stir.

Comparative Example-2 The same operation as in Example-1 was performed except that 1.25 g of sorbitan monostearate was used as a dispersant. 8
6.5 g of sodium polyacrylate fine particles were obtained, and the average particle size was 50-.

Furthermore, considerable deposits were observed inside the reaction tank.

Comparative Example 3 In Example 1, polymerization was carried out using only the oil-soluble cationic copolymer without adding any nonionic surfactant.
87.8 g of sodium polyacrylate was obtained, and almost no adhesion was observed in the reaction tank. However, the median particle size of the obtained polymer was 320-, 25% diameter, 7
The 5% diameter is 200.445-, respectively, and Example-1
The particle size distribution was wide compared to that of .

〔Effect of the invention〕

As specifically explained in the examples, the polymer produced by reverse-phase suspension polymerization according to the method of the present invention has an average particle size of several hundreds, and the particle size distribution is It is narrow and contains few coarse and fine powders. Moreover, since there are almost no polymer aggregates in the reaction tank, it has the effect of allowing repeated production without having to remove deposits inside the tank, significantly improving workability and productivity. .

Claims (1)

[Claims] 1. When carrying out reverse phase suspension polymerization of a water-soluble ethylenically unsaturated monomer in a hydrophobic solvent, 70 to 99.5 mol% of a lipophilic ethylenically unsaturated monomer and , an oil-soluble cationic copolymer (A
) and a nonionic surfactant (B) as a dispersant. 2. 0.1 to 10% by weight of the oil-soluble cationic copolymer (A) and 0.05 to 5% by weight of the nonionic surfactant (B) based on the water-soluble ethylenically unsaturated monomer. % of the polymer particles according to claim 1. 3. The lipophilic ethylenically unsaturated monomer is styrene or alkyl-substituted styrene, and the ethylenically unsaturated monomer having a quaternary ammonium group is dialkylaminoalkyl (meth)acrylate quaternary salt or dialkylamino The method for producing polymer particles according to claim 1 or 2, which is an alkyl (meth)acrylamide quaternary salt. 4. The method for producing polymer particles according to any one of claims 1 to 3, wherein the nonionic surfactant (B) is a sucrose fatty acid ester and/or a sorbitan fatty acid ester. .