JPH05125117A - Production of water-soluble polymer - Google Patents

Abstract

PURPOSE:To efficiently obtain without causing gelation the title polymer of high molecular weight useful as e.g. a flocculant by suspension polymerization of an N-vinylcarboxylic acid amide by a specific means followed by acidic hydrolysis of the resulting polymer. CONSTITUTION:Firstly, >=20wt.% of water of the whole water to be used is suspended, in advance, in a hydrocarbon dispersion medium (pref. n-hexane) in the presence of a dispersant (pref. polyoxyethylene alkyl ether). Thence, an N-vinylcarboxylic acid amide of the formula (R is H or methyl)(pref. N- vinylformamide) or its mixture with another water-soluble vinyl compound copolymerizable therewith is added to the suspension either directly or in the form of an aqueous solution incorporated with the rest of the water, and suspension polymerization of the monomer(s) is carried out in the presence of the dispersion medium, water, dispersant and a polymerization initiator (pref. 2,2'- azobis-2-amidinopropane hydfochloride) followed by acidic hydrolysis of the resulting polymer using pref. hydrogen chloride.

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 apt to gel (insolubilize water) in the hydrolysis step, and it is possible to efficiently produce a powdery water-soluble polymer of high quality. It was difficult.

[0004]

The inventors of the present invention have conducted diligent studies on the above-mentioned problems, and as a result, when the polymerization was carried out by a specific method, after the suspension polymerization and after the acidic hydrolysis, The present inventors have found that the modified polymer of (1) is prevented from gelling and a powdery high-molecular weight water-soluble polymer is obtained.

That is, the gist of the present invention is that a monomer represented by the general formula

[0006]

Embedded image CH ₂ ═CHNHCOR

(In the formula, R represents a hydrogen atom or a methyl group), N-vinylcarboxylic acid amide alone,
Alternatively, a mixture of the N-vinylcarboxylic acid amide and another water-soluble vinyl compound copolymerizable with the N-vinylcarboxylic acid amide is subjected to suspension polymerization in the presence of a hydrocarbon-based dispersion medium, water, a dispersant and a polymerization initiator, and then acid hydrolysis. In the method for producing a water-soluble polymer by decomposing, 20% by weight or more of the total amount of water used is suspended in advance in a hydrocarbon dispersion medium in the presence of a dispersant, and then the monomer is used as it is, or, It exists in the manufacturing method of the water-soluble polymer characterized by adding as the aqueous solution which added the remaining water.

The present invention will be described in detail below. Formula CH ₂ = CHNHCOR (wherein, R represents a hydrogen atom or a methyl group.) Used in the present invention as the N- vinylcarboxamide represented by include N- vinylformamide and N- vinylacetamide However, for the purpose of obtaining a modified product of the N-vinylcarboxylic acid amide polymer, N-vinylformamide is preferable because the polymer has good hydrolyzability.

In the polymerization of the present invention, N-vinylcarboxylic acid amide alone or a mixture of N-vinylcarboxylic acid amide and another water-soluble vinyl compound is used as a monomer. As the water-soluble vinyl compound, a compound that is copolymerizable with N-vinylcarboxylic acid amide and is substantially insoluble in the hydrocarbon-based dispersion medium used in the present invention is used. Acrylonitrile, methacrylonitrile, acrylamide,
Examples thereof include water-soluble vinyl compounds such as methacrylamide, acrylic acid, methacrylic acid, acryloyloxyethyl trimethyl ammonium chloride, and methacryloyl oxyethyl trimethyl ammonium chloride.

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 hydrocarbon-based dispersion medium used in the suspension polymerization of the present invention is preferably a hydrocarbon azeotropic with water. For example, chain saturated hydrocarbons such as n-hexane, n-heptane, n-octane, nonane, decane, undecane, dodecane, petroleum fraction having a boiling point of 65 to 250 ° C, preferably petroleum fraction having a boiling point of 80 ° C to 180 ° C, Examples thereof include alicyclic hydrocarbons such as cyclohexane and methylcyclohexane, and aromatic hydrocarbons such as benzene, toluene, xylene and ethylbenzene.

As the dispersant, a non-emulsifying oil-soluble polymer or a general surfactant is usually used. Examples of the non-emulsifiable oil-soluble polymer include oil-soluble celluloses such as ethyl cellulose and hydroxyethyl cellulose, and adducts of olefins with maleic anhydride. Also,
As the surfactant, 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.

As the polymerization initiator, a general radical polymerization initiator can be used, but an azo compound is preferable. Particularly preferred is a water-soluble azo compound,
2,2'-azobis-2-amidinopropane hydrochloride,
Sulfates and acetates, azobis-N, N'-dimethyleneisobutylamidine hydrochlorides, sulfates and acetates,
Examples thereof include alkali metal salts and ammonium salts of 4,4′-azobis-4-cyanovaleric acid. The radical polymerization initiator is usually used in an amount of 10 based on the weight of the raw material monomers.
0 to 10000 ppm, preferably 500 to 5000
Used in the ppm range.

Further, in some cases, various additives may be used as a polymerization stabilizer, and, for example, ammonium chloride, calcium chloride, etc. are usually used in an amount of 1 to 1 with respect to the monomer.
10% by weight is used. Suspension polymerization is performed in a reaction system in which water is added to the above-described monomer, hydrocarbon-based dispersion medium, dispersant, and polymerization initiator. A feature of the polymerization method of the present invention is the step of adding a monomer to the reaction system during the polymerization.

In the conventional suspension polymerization method, an aqueous solution containing both a monomer and a polymerization initiator is prepared in advance, the aqueous solution is added to a dispersion medium with stirring, and the aqueous solution is added in the form of water droplets to the dispersion medium. The method of dispersing and polymerizing is generally used. And, even by the conventional method, it is possible to obtain a water-soluble polymer without polymerizing, modifying and gelling. However, the water-soluble polymer obtained by adopting the conventional method is limited to the case of a relatively low molecular weight. Usually, in order to obtain a polymer having a high molecular weight, means such as reducing the amount of the polymerization initiator in the reaction system or increasing the concentration of the aqueous monomer solution is selected. The effect is strong, and gelation tends to be remarkable when the concentration of the aqueous monomer solution is, for example, 20% by weight or more, particularly 30% by weight or more.

The polymerization method of the present invention will be described in more detail below. The amount of water used for suspension polymerization is usually 0.1 to 3 times by weight, preferably 0.4
~ 2 times the weight. If it is more than the range, the molecular weight tends to decrease, and if it is less than the range, dispersion of water droplets becomes insufficient. The amount of the dispersion medium is usually 0.5 to 10 times, preferably 1 to 5 times the total amount of the above-mentioned monomer and water.

20% by weight or more, preferably 50% by weight or more, particularly preferably 90% by weight or more of the total amount of water used is added to the dispersion medium in advance and a suspension phase is formed by stirring, and then, The monomer is added as it is or as an aqueous solution with the remaining water added. When the amount of water added to the suspension phase is 20% by weight or less, the difference in gelation preventing effect as compared with the conventional method becomes unclear.

The method of adding the monomer or the monomer aqueous solution is usually to slowly drop the monomer little by little. When the polymerization is carried out using a batch reactor, it is usually 0.5 to 8 hours, preferably 1 to add the whole amount.
It takes ~ 5 hours. During this period, there is no particular problem even if it is added intermittently to some extent, but it is not efficient in operation even if it takes more time than the above range, and the molecular weight of the polymer tends to decrease. On the other hand, if it is added earlier than this range, the conditions of the polymerization system are substantially the same as those in the conventional method, which is not preferable. In addition, it is generally preferable to extend the monomer addition time as the amount of water used for polymerization is reduced.

The above polymerization reaction is generally carried out at 30 to 100 ° C., preferably 40 to 80 ° C. under an inert gas stream, and the total reaction time including the above-mentioned monomer addition time is 0.5 to 1
It is carried out under the condition of 0 hours, preferably 1 to 8 hours. In addition, in the polymerization of the present invention, the polymerization initiator and the polymerization stabilizer may be added to either the bed liquid under suspension or the monomer side to be supplied, but usually, it is added to the bed liquid. It is desirable to put it.

The polymer obtained by the above method is usually provided for acidic hydrolysis as a solution or dispersion containing the polymer. Examples of the acid include hydrogen chloride, hydrogen bromide, hydrogen fluoride, sulfuric acid, nitric acid, sulfamic acid, alkanesulfonic acid, and the like, preferably hydrogen chloride, and the introduction form of the reaction system is gaseous, It may be in the form of aqueous hydrochloric acid.

The amount of the acid used is appropriately determined according to 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
In the case of N-vinylformamide polymer, 20 to 130
℃, preferably 60 to 120 ℃, in the case of N-vinyl acetamide polymer, 50 to 150 ℃, preferably 9
It is 0 to 130 ° C. If necessary, it is carried out in a pressure reaction system.

The hydrolyzed modified product is, as it is or after being neutralized, separated by solvent dehydration or azeotropic distillation of a dispersion medium to water, and recovered as a powdery water-soluble polymer.

[0022]

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 Cyclohexane 400 was placed in a 1 L 4-necked flask equipped with a stirrer, a cooling tube, a dropping funnel and a nitrogen gas introducing tube.
g, polyoxyethylene oleyl ether (Daiichi Kogyo Seiyaku Co., Ltd., trade name “Neugen ET140E”, HL.
B. = 14.0) 2 g, water 83 g, ammonium chloride 7
g was added and the temperature was raised to 55 ° C. with stirring.

Next, 2.7 g of a 10% by weight aqueous solution of 2,2'-azobis-2-amidinopropane dihydrochloride was added under a stream of nitrogen gas, and then N-vinylformamide (purity = 9) was added.
79%, acrylonitrile (purity = 99.5)
%) 65 g of a mixed solution was added dropwise over 3 hours. After that, the reaction was further continued for 3 hours. 500 g of the above reaction liquid 100 g
The mixture was transferred to a ml flask, 19.4 g of concentrated hydrochloric acid (1.3 times the molar amount relative to N-vinylformamide) was added, and the mixture was stirred under stirring 9
It was hydrolyzed at 5 ° C. for 5 hours. After cooling to room temperature, concentrated hydrochloric acid −
200 ml of a mixed solution of methanol (volume ratio 1: 9) was added, washed with stirring, filtered, and dried under reduced pressure to recover a polymer.

The reduced viscosities of the polymers obtained in Table 1 (η
sp / c) and the results of solubility in water are shown. -Method of measuring reduced viscosity (ηsp / c) After 0.1 g of a polymer sample was immersed in 100 g of 1N saline for 4 hours at room temperature and then dissolved, the reduced viscosity was measured with an Ostwald viscometer at 25 ° C. -Evaluation of Solubility in Water The amount of insoluble matter when 0.1 g of the polymer sample was dissolved in 100 g of water by stirring at room temperature for 4 hours was visually observed and judged according to the following criteria. ○ There is no insoluble matter. △ There is a very small amount of small insoluble matter. × A large amount of insoluble matter is present.

Examples 2 to 4 Table 1 shows the results of experiments conducted in the same manner as in Example 1 except that the amount of water added to the polymerization system was changed to 136 g and 204 g. In addition, in Example 4, an experiment was performed under the same conditions as in Example 3 except that ammonium chloride was not used.

Examples 5 to 9 Table 1 shows the results of the same experiment as in Example 1 except that the water used for polymerization was divided into the proportions shown in Table 1 and added to the reaction system.

Comparative Examples 1 to 3 The same amount of the dispersion medium and the dispersant as in Examples 1 to 3 was used as the base liquid, and the same amount of the monomers, water, polymerization initiator and chlorination as those used in Examples 1 to 3 were added to the liquid. The results of experiments conducted by adding ammonium are shown in Table 1.

[0028]

[Table 1]

[0029]

EFFECTS OF THE INVENTION According to the present invention, a high molecular weight water-soluble polymer starting 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.

Claims (2)

[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) as a monomer, or the N-vinylcarboxylic acid amide alone.
Suspension polymerization of a mixture of a vinylcarboxylic acid amide and another water-soluble vinyl compound that is copolymerizable in the presence of a hydrocarbon-based dispersion medium, water, a dispersant and a polymerization initiator, and then acidic hydrolysis. 20% by weight of the total amount of water used in the presence of a dispersant,
A method for producing a water-soluble polymer, which comprises suspending the above in a hydrocarbon dispersion medium in advance and then adding the monomer as it is or as an aqueous solution containing the remaining water. 2. The method according to claim 1, wherein the total amount of water used is 0.1 to 3 times the weight of the monomer.