JPH0586115A - Production of water-soluble polymer - Google Patents

Abstract

PURPOSE:To produce a water-soluble powdery polymer of high quality without causing gelation by polymerizing an N-vinylcarboxamide by suspension polymerization in the presence of a specific compound and hydrolyzing the polymer with hydrogen chloride. CONSTITUTION:An N-vinylcarboxamide represented by the formula (wherein R is H or CH3) is polymerized alone or with other water-soluble vinyl compound(s) copolymerizable therewith (e.g. (meth)acrylonitrile), by suspension polymerization conducted in the presence of an ammonium halide (e.g. ammonium chloride) and/or a calcium halide (e.g. calcium chloride). The polymer is then hydrolyzed with hydrogen chloride to produce a water-soluble polymer. Thus, a water-soluble polymer can be efficiently produced from an N- vinylcarboxamide without causing gelation. This polymer is utilizable in a variety of industrial fields as a flocculant, papermaking additive, etc.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing a water-soluble polymer. Specifically, it relates to a method for producing a modified product of a water-soluble N-vinylcarboxylic acid amide (co) polymer.

[0002]

BACKGROUND OF THE INVENTION N-Vinylcarboxylic acid amide polymers are prepared by suspension polymerization of a mixture of N-vinylcarboxylic acid amides, and optionally other water-soluble vinyl compounds, and further hydrolysis of the polymer. A method for obtaining a water-soluble modified product is known (Japanese Patent Laid-Open No. 61-141712). The modified polymer is expected to have an excellent effect as a coagulant for dehydrating organic sludge, a chemical for paper and the like.

[0003]

However, in the conventional method, the modified product is easily gelled (water-insolubilized) in the hydrolysis step, and it is possible to efficiently produce a high-quality powdery water-soluble polymer. It was difficult.

[0004]

The inventors of the present invention have made extensive studies in view of the above-mentioned problems, and as a result, by adding a specific compound during the polymerization, gelation of the modified product was prevented and the powdered product was obtained. The present invention has been accomplished by finding that the water-soluble polymer can be obtained. That is, the gist of the present invention is the general formula

[0005]

Embedded image N ₂ -vinylcarboxylic acid amide represented by CH ₂ ═CHNHCOR (wherein R represents a hydrogen atom or a methyl group) or the N-vinylcarboxylic acid amide
In a method for producing a water-soluble polymer by suspension-polymerizing a mixture of a vinylcarboxylic acid amide and another water-soluble vinyl compound which is copolymerizable, and then hydrolyzing the mixture with hydrogen chloride, an ammonium halide is used in the polymerization system. And / or the presence of calcium halide in a process for producing a water-soluble polymer. Hereinafter, the present invention will be described in detail. General formula used in the present invention

[0006]

Embedded image Examples of the N-vinylcarboxylic acid amide represented by CH ₂ ═CHNHCOR (wherein R represents a hydrogen atom or a methyl group) include N-vinylformamide and N-vinylacetamide. For the purpose of obtaining a modified carboxylic acid amide polymer, N-
Vinylformamide is preferred. For the polymerization of the present invention, N-
Vinylcarboxylic amides alone or mixtures of N-vinylcarboxylic amides with other water-soluble vinyl compounds are used. As the water-soluble vinyl compound, a compound that is copolymerizable with N-vinylcarboxylic acid amide and is substantially insoluble in the hydrocarbon solvent used in the present invention is used. Acrylonitrile, methacrylonitrile, acrylamide, methacrylamide, acryl Acid, methacrylic acid,
Water-soluble vinyl compounds such as acryloyloxyethyltrimethylammonium chloride and methacryloyloxyethyltrimethylammonium chloride are exemplified.

When the N-vinylcarboxylic acid amide (A) is copolymerized with the above water-soluble vinyl compound (B),
The copolymerization molar ratio of (A) and (B) is usually 20: 80-9.
It is 5: 5, preferably 30:70 to 90:10, and more preferably 40:60 to 80:20, but is not particularly limited to this range. The above-mentioned raw material vinyl compound is dispersed in a dispersion medium in the form of an aqueous solution and subjected to suspension polymerization. The aqueous solution concentration of the raw material monomer is polymerized at any concentration within the range of 5 to 95% by weight, but it is 20 to obtain a high molecular weight polymer.
-80 wt% is preferred. As the dispersion medium, for example, n-
Chain saturated hydrocarbons such as hexane, n-heptane, n-octane, nonane, decane, undecane and dodecane, petroleum fraction having a boiling point of 65 to 250 ° C, preferably boiling point of 80 ° C to 1
Examples include petroleum fractions at 80 ° C., alicyclic hydrocarbons such as cyclohexane and methylcyclohexane, and aromatic hydrocarbons such as benzene, toluene, xylene, and ethylbenzene. The dispersion medium is usually an aqueous solution of the raw material vinyl compound,
It is used in a range of 0.5 to 10 times by weight, preferably 1 to 5 times by weight.

In the polymerization, a non-emulsifying oil-soluble polymer or a general surfactant is usually used as a dispersion stabilizer. As the non-emulsifying oil-soluble polymer,
Examples thereof include oil-soluble cellulose such as ethyl cellulose and hydroxyethyl cellulose, and adducts of olefins and maleic anhydride. The surfactant is preferably H.I. L. B. A nonionic surfactant having a ratio of 9 or more, for example, polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, etc. is used. The amount of the above dispersion stabilizer used is usually 0.01 to 5% by weight, preferably 0.05 to 1% by weight, based on the dispersion medium.
Is. A general radical polymerization initiator can be used as the polymerization initiator, but an azo compound is preferable.
Particularly preferred is a water-soluble azo compound, which is 2,2'-
Azobis-2-amidinopropane hydrochloride, sulfate and acetate, azobis-N, N′-dimethyleneisobutylamidine hydrochloride, sulfate and acetate, 4,4′-azobis-4-cyanovaleric acid Examples thereof include alkali metal salts and ammonium salts. The radical polymerization initiator is usually 100 to 10 on a weight basis with respect to the raw material vinyl compound.
It is used in the range of 000 ppm, preferably 500 to 5000 ppm.

The present invention requires the presence of ammonium halide and / or calcium halide in the above polymerization system as an essential requirement. Examples of the halide include ammonium chloride, ammonium bromide, calcium chloride, calcium bromide, calcium iodide and the like, but ammonium chloride is preferable. The amount of the halide to be used is usually 0.1% with respect to the total amount of the monomers (monomer purity is 100%).
It is 1 to 20% by weight, preferably 1 to 15% by weight. When the amount used is small, the effect of preventing gelation of the target polymer modified product becomes weak. Conversely, even if the amount used exceeds the range, the effect of preventing gelation is constant and not economical,
In addition, the molecular weight of the polymer tends to be slightly decreased. After the polymerization by using the above specific halide, gelation of the modified product of the polymer obtained by further hydrolyzing with hydrochloric acid is prevented, but at the time when the polymerization is substantially completed. However, even if ammonium chloride or the like is added to the reaction solution, the effect of preventing gelation is not recognized. Therefore, it is presumed that the addition effect of the specific halogen compound of the present invention removes the gelling factor existing at the time of polymerizing the monomer.

The polymerization temperature in the process of the present invention is usually 30.
To 100 ° C., and the polymerization time is usually 0.5 to 1
It is 0 hour, preferably 1 to 8 hours. During the polymerization, heat of polymerization is generated, and therefore the polymerization temperature is usually adjusted by cooling the polymerization system so that the polymerization temperature is maintained within the above range. To carry out the polymerization, a water-insoluble organic solvent containing a dispersant is kept under the polymerization conditions, and a monomer aqueous solution containing a polymerization initiator, ammonium chloride, etc. is gradually supplied to the mixture under stirring to carry out the polymerization. However, the mixing order of the raw material, the solvent, and the auxiliary is not particularly limited. By the suspension polymerization described above, after the raw material vinyl compound is polymerized in the dispersion medium to form polymer particles, hydrogen chloride can be added to start the hydrolysis reaction. In this case, hydrogen chloride may be introduced into the reaction system in a gaseous form, or may be added as an aqueous hydrochloric acid solution.

At the time of hydrolysis, the higher the concentration of the polymer in the water-containing polymer is, the faster the modification rate is. Therefore, it is preferable to use a saturated aqueous solution. If necessary, the water-containing N-vinylcarboxylic acid amide polymer may be dehydrated by azeotropic distillation of water as a dispersion medium, and then hydrogen chloride may be added. The amount of hydrogen chloride used is appropriately used depending on the desired hydrolysis rate, but is usually 1 to 2 times the equivalent of the amide group having the desired hydrolysis rate. The temperature of hydrolysis is 20 to 130 ° C. in the case of N-vinylformamide polymer, preferably 60 to
The temperature is 120 ° C, and in the case of N-vinylacetamide polymer, it is 50 to 150 ° C, preferably 90 to 130 ° C. If necessary, it is carried out in a pressure reaction system. The hydrolyzed modified product is, as it is, or subjected to a neutralization treatment, separated by solvent dehydration or azeotropic distillation of a dispersion medium to water, and recovered as a powdery water-soluble polymer.

[0012]

EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded. Example 1 To a 1-liter 4-necked flask equipped with a stirrer, a cooling tube, a dropping funnel and a nitrogen gas introducing tube, toluene 40 was used as a dispersion medium.
0 g and polyoxyethylene oleyl ether (Daiichi Kogyo Seiyaku Co., Ltd., trade name "Neugen ET104E", HL.
(B = 14.0) 2 g was added and the temperature was raised to 60 ° C. with stirring.
Next, under a nitrogen gas stream, in a dropping funnel, 76 g of N-vinylformamide (purity = 93.0%), 53 g of acrylonitrile (purity = 99.5%), 2,2′-azobis-2-amidinopropane 2 Water was added to 0.2 g of hydrochloride and 6.4 g of ammonium chloride as an additive to obtain a total amount of 210
The solution of g was added dropwise to the above dispersion medium, which was kept at 60 ° C., under stirring for 3 hours. Then, the reaction was carried out at 60 ° C. for 3 hours under stirring in a nitrogen gas stream.

100 g of the above reaction solution was transferred to a 500 ml flask, 36.7 g of concentrated hydrochloric acid (1.3 times the molar amount relative to N-vinylformamide) was added, and hydrolysis was carried out at 95 ° C. for 5 hours while stirring. After cooling to room temperature, 200 ml of a concentrated hydrochloric acid-methanol mixed solution (volume ratio 1:10) was added, washed with stirring, filtered, and dried under reduced pressure to recover a polymer. Table 1
The results of the reduced viscosity (ηsp / c) and water solubility of the obtained polymer are shown below. ° Reduced viscosity (ηsp / c) measurement method 0.1g of polymer sample was immersed in 100g of 1N saline for 4 hours at room temperature and then dissolved, and then reduced viscosity was measured at 25 ° C with Ostwald viscometer. did. Evaluation of Solubility in Water The amount of insoluble matter when 0.1 g of a polymer sample was dissolved in 100 g of water by stirring for 4 hours at room temperature was visually observed and judged according to the following criteria. ○ There is no insoluble matter at all. △ There is a very small amount of small insoluble matter. X There is a large amount of insoluble matter.

Examples 2 to 4 and Comparative Examples 1 to 5 The same as Example 1 except that the polymerization temperature, the type of dispersion medium, the type and amount of additives were changed as shown in Table 1 in Example 1. The results of the experiments are shown in Table 1. Example 5 In Example 2, the total amount of raw material monomers was N-vinylformamide, the dispersion medium was cyclohexane, and the polymerization temperature was 7.
Table 1 shows the results of the same experiment as in Example 2 except that the temperature was 0 ° C. Comparative Example 6 Table 1 shows the results of the same experiment as in Example 1 except that ammonium chloride was added to the reaction solution after polymerization in Example 1.

[0015]

According to the present invention, a water-soluble polymer made from N-vinylcarboxylic acid amide can be efficiently produced without gelation. The water-soluble polymer is expected to be widely used in many industrial fields as a flocculant, a drug for paper and the like.

[0016]

[Table 1]

Claims (1)

[Claims] 1. An N-vinylcarboxylic acid amide represented by the general formula: CH ₂ ═CHNHCOR (wherein R represents a hydrogen atom or a methyl group), or the N-vinylcarboxylic acid amide alone.
In a method for producing a water-soluble polymer by suspension-polymerizing a mixture of a vinylcarboxylic acid amide and another water-soluble vinyl compound which is copolymerizable, and then hydrolyzing the mixture with hydrogen chloride, an ammonium halide is prepared in the polymerization system. And / or the presence of a calcium halide.