JPS5918407B2 - Method for producing bead-shaped polymer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing bead-shaped water-soluble cationic polymers, and more specifically, the present invention relates to a method for producing bead-shaped water-soluble cationic polymers.
The present invention relates to a method of polymerizing a monomer containing DAA (hereinafter referred to as DAA) into a bead-shaped polymer.

Water-soluble polymers obtained by polymerizing monomers containing DAA are useful, for example, as flocculants, and their production methods are generally disclosed in Japanese Patent Publication No. 34-10644 and Japanese Patent Publication No. 34-1064.
A suspension polymerization method as described in Japanese Patent No. 7-15033 is known.

This polymerization method is a method in which an inert dispersion medium and an aqueous monomer solution are polymerized as a water-in-oil or oil-in-water emulsion using a nonionic emulsifier in the presence of a catalyst. This method is preferred because the polymerization heat generated by polymerization is easily removed, the polymer does not deteriorate due to heat, and a polymer with a high molecular weight cannot be obtained. However, the resulting polymer tends to be in the form of fine powder. I tend to say
If the polymer is in the form of a fine powder, for example, when it is used as a flocculant, it will contain air bubbles when dissolved in water, slowing down the dissolution rate, and it will also generate dust during the dissolution process, worsening the working environment. . Conventionally, attempts have been made to carry out polymerization by changing the state of the emulsion by changing the proportion of the dispersion medium, stirring conditions, etc. in order to increase the particle size of the obtained polymer, but these methods have not yielded fully satisfactory results. It has not been done. On the other hand, in recent years, a method has been known in which a monomer aqueous solution is well dispersed by using ethyl cellulose as a dispersant, and furthermore, the dispersed droplets are kept stable and polymerization is carried out in a water-in-oil type to obtain bead-shaped polymers. ing.

Although this method is an excellent method for producing bead-shaped polymers, the nature of ethylcellulose and the dispersion medium are viscous, so it requires some steps to separate the polymer after polymerization.
It becomes troublesome. Therefore, if the amount of ethyl cellulose used can be reduced, this problem will not occur and it is also preferable from an economical point of view. Furthermore, it is conceivable to recover ethylcellulose from the mixture after polymerization and reuse it in the next reaction, but the function of recovered ethylcellulose as a dispersant for producing beaded polymers tends to be significantly reduced. . Therefore, it is preferable if the function of the recovered ethylcellulose as a dispersant can be improved since it can be reused. In view of the above circumstances, the present inventors conducted various studies on methods for improving the function of ethyl cellulose as a dispersant when producing bead-shaped polymers by suspension polymerizing DAA using ethyl cellulose as a dispersant. By using ethyl cellulose that has been treated with Completed the invention.

That is, the gist of the present invention is to convert DAA alone or a mixture of the monomer and a copolymerizable monomer into a water-in-oil type in the presence of a catalyst in a mixture consisting of a hydrocarbon dispersion medium, water, and a dispersant. A method for producing a bead-shaped polymer, characterized in that in the suspension polymerization method, ethyl cellulose obtained by contact treatment with an aqueous caustic alkali solution containing 0.1 to 10% by weight of the monomer is used as a dispersant. . The present invention will be explained in detail below.

The DAA targeted by the present invention has the following general formula (1) (wherein,
R1 is a hydrogen atom or a methyl group, R2 and R3 are a straight chain or branched alkyl group having 1 to 4 carbon atoms, R2 and R3 may be the same, R4 is a hydrogen atom, and R4 is a hydrogen atom or a methyl group;
~8 linear or branched alkyl group, a hydroxy-substituted alkyl group having 1 to 4 carbon atoms, or a benzyl group.

Y represents an alkylene group having 2 to 4 carbon atoms or a hydroxy-substituted alkylene group. X7 represents a halogen ion such as Ct or Br, a sulfate ion, a nitrate ion, a phosphate ion, a carboxylate ion, a sulfonate ion, an alkyl sulfate ion having an alkyl group having 1 to 8 carbon atoms, or the like. ) is a compound represented by.

For example, dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, diethylaminoethyl acrylate, diethylaminoethyl methacrylate,
Dibutylaminoethyl acrylate, dibutylaminoethyl methacrylate, etc. and hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid,
Neutralized salts with acids such as acetic acid, propionic acid, benzenesulfonic acid and β-methacryloyloxyethyltrimethylammonium chloride, β-methacryloyloxyethyltrimethylammonium methylsulfate, β
-methacryloyloxyethyldimethylethylammonium bromide, β-methacryloyloxyethyldimethylethylammonium monoethyl sulfate, β-
Examples include quaternized products such as methacryloyloxyethyldimethylbenzylammonium chloride, β-acryloyloxyethyltrimethylammonium chloride, β-acryloyloxyethyltriethylammonium bromide, and 2-hydroxy-3methacryloyloxypropyltrimethylammonium chloride. The cationic high molecular weight water-soluble polymer that is the object of the present invention is
The compound represented by the general formula (1) alone, or the compound represented by the general formula (
Examples include copolymers with monomers copolymerizable with the compound represented by 1), such as acrylamide, methacrylamide, vinylpyridine neutralized salts or quaternized products, and dimethyldiallylammonium compounds. In the case of this copolymer, the content of DAA is usually 5 mol% or more, preferably 10 mol% or more. The dispersion medium used in the present invention is usually an alicyclic hydrocarbon such as cyclohexane, cyclopentane, cycloheptane, methylcyclohexane, or cyclooctane, or an aromatic hydrocarbon such as benzene, toluene, xylene, ethylbenzene, chlorobenzene, or dichlorobenzene. Examples include hydrocarbons such as hydrogen.

These dispersion media are usually used in an amount of 1 to 10 times the weight of the monomer, preferably 1 to 5 times the weight of the monomer. In the present invention, it is essential to use ethyl cellulose obtained by contact treatment with an aqueous caustic solution as a dispersant. Caustic alkali is caustic soda or caustic potash,
It is usually used as an aqueous solution of 0.1 to 47% by weight.
If the concentration of caustic alkali is too low, sufficient effects cannot be obtained. The contact temperature is usually 20 to 80°C, and the contact time varies somewhat depending on the concentration of caustic alkali and the contact temperature, but is usually about 10 to 120 minutes under the above conditions. The contact treatment is usually carried out by adding ethyl cellulose to an aqueous caustic solution and stirring and holding the ethyl cellulose slurry for a predetermined period of time.

After the treatment, the ethyl cellulose powder is usually filtered out, washed with water, and, if necessary, dried and recovered. The ethyl cellulose used in the caustic contact treatment may be fresh, or it may be recovered ethyl cellulose that has been used as a dispersant in the reaction of the present invention.

When using fresh ethyl cellulose, excellent effects can be obtained even when the amount used as a dispersant is reduced, while when using recovered ethyl cellulose, the effect is comparable to that of untreated, fresh ethyl cellulose. can be obtained. The amount of dispersant used varies somewhat depending on the reaction conditions, but is usually 0.1 to 10% by weight, preferably 0.3 to 5% by weight, based on the monomer; if this amount is too small, the resulting polymer If the amount is too large, the polymer particles tend to solidify together when the polymer is dried, and furthermore, the solubility of the product polymer in water decreases, which is not preferable.

Polymerization in the present invention is usually carried out by charging a dispersion medium and a dispersant into a reactor, adding a separately prepared monomer aqueous solution and a catalyst, and mixing and stirring to form a water-in-oil suspension in the dispersion medium, water, and dispersant. It is possible to form a state and carry out polymerization.

The concentration of the monomer aqueous solution at this time is usually 10 to 80% by weight, preferably 40 to 80% by weight. Ideally, the stirring state is such that good dispersion is achieved and the dispersed particles are large. Catalysts usually include peroxides such as ammonium persulfate, potassium persulfate, hydrogen peroxide, etc.
,2″-azobis-2-amidinopropane hydrochloride, 4,
Known water-soluble catalysts such as azo compounds such as 4'-azobis-4-cyanopentanoictaacid can be mentioned.

In the case of peroxides, they can also be used as redox catalysts in combination with reducing agents such as sodium metabisulfite, sodium sulfite, and ferrous chloride. The amount of these catalysts used is usually about 10 to 3000 ppm based on the monomer. The polymerization temperature varies somewhat depending on the type of monomer used, but is usually from 35°C to the boiling point of the mixture, preferably from 40 to 70°C.

After polymerization, the produced polymer is separated from the mixture,
By washing the polymer and drying it according to a conventional method, a uniform bead-like polymer is recovered. On the other hand, a mother liquor consisting of a dispersion medium and water containing ethylcellulose is usually recovered by distilling off the dispersion medium, and recovering the ethylcellulose precipitated in the remaining water. The ethyl cellulose recovered here was treated with caustic alkali as described above, and then treated again.
Can be used in polymerization. Next, the present invention will be explained in more detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist thereof.

Example 1 1t with temperature control device, stirrer and monomer supply port
In a closed reactor, 1 ethylcellulose (manufactured by Hercules, trade name T-100) was stirred in a 5Wt0/) caustic soda aqueous solution 1009 at a temperature of 8°C for 2 hours, filtered, suspended and washed. Ethylcellulose 1.89 (0.7 wt% based on monomer) obtained by drying and 2cyclohexane 3509 (1.27 wt% based on monomer)
The system was kept in a degassed state with N2 gas, and the liquid temperature was heated to 50°C. p. To this was added 61.m of acrylamide, which had been previously degassed with N2 gas, under stirring.
79 and dimethylaminoethyl acrylate hydrochloride 12
A 66 wt % aqueous solution containing 0.09 (40% based on all monomers) and 2,25-azobis-2-amidinopropane hydrochloride 0.279 (1,500 ppm based on monomers) was gradually mixed dropwise over 60 minutes. Then, stirring was continued for an additional 60 minutes.

Note that the temperature at this time was in the range of 50 to 55 degrees Celsius.
After the reaction was completed, the mixture was filtered through F to recover the produced polymer, which was washed with water and dried, and the state of the particles was observed, and the results shown in Table 1 were obtained. On the other hand, the finished liquid was slowly and dropwise supplied to a distillation apparatus lined with water at 85°C, cyclohexane and water were azeotropically distilled off, and finally the ethyl cellulose remaining in the water was filtered out and recovered.

Example 2 Ethyl cellulose recovered by the same force method as in Example 1 was treated with caustic soda in the same manner as in Example 1, and 0.14 wt% of the monomer was used, under the same conditions as in Example 1. The reaction was carried out.

Claims (1)

[Claims] 1 A neutralized salt of dialkylaminoalkyl (meth)acrylate and/or a quaternized monomer alone, or a mixture of the monomer and a copolymerizable monomer, in a mixture consisting of a hydrocarbon dispersion medium, water, and a dispersant. In a water-in-oil suspension polymerization method in the presence of a dissolving medium, ethyl cellulose obtained by contact treatment with a caustic alkali aqueous solution of 0.1 to 10% by weight based on the monomer is used as a dispersant. A method for producing a bead-shaped polymer characterized by: