JPS63293188A - Method for producing polymeric acids - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing a water-soluble polymeric acid. Specifically, when releasing a salt of a water-soluble polymeric acid to obtain the polymeric acid, an electrodialysis device in which amphoteric ion exchange membranes and cation exchange membranes are arranged alternately is used to release the salt of the water-soluble polymeric acid. A step of neutralizing the mixed solution of the released neutral salt and chloride, and an electrodialysis device equipped with a bipolar membrane and an anion and cation exchange membrane for discharging the neutralized solution. The present invention relates to a method for producing a polymeric acid, which comprises a step of regenerating it into an acid and an alkali.

[Prior art and its problems] Conventionally, methods for obtaining free water-soluble polymeric acids include, for example, methods of polymerizing water-soluble unsaturated acids, and methods of polymerizing salts of polymeric acids with acids, ion exchange resins, or ion exchange membranes. By electrodialyzing using 1 m2 of the polymer, 1! There is a way to make it a.

However, in the method of polymerizing water-soluble unsaturated acids, it is difficult to polymerize any desired polymeric acid.

In addition, in the method of converting a salt of a polymeric acid by conversion, it is necessary to use an acid stronger than the polymeric acid.
A strong acid salt is produced as a by-product, and a solid phase forms when separated from the target polymeric acid. Furthermore, the method using an ion exchange resin has a problem in that the conversion rate to a polymeric acid is low and the ion exchange resin in the IC needs to be regenerated.

[Problem that the invention seeks to solve]

On the other hand, a method of converting a water-soluble polymeric acid salt into a polymeric acid by electrodialysis using a cation exchange membrane was disclosed in Japanese Patent Laid-open No. 5
As described in Japanese Patent Application No. 9-173282, the above-mentioned problems of the conventional technology can be solved and the desired water-soluble polymeric acid can be obtained, but the salt of the polymeric acid can diffuse through the cation exchange membrane. , the conversion rate to polymeric acids is extremely poor. Therefore, in a method using electrodialysis using such a cation exchange membrane, in order to improve the conversion rate from a salt of a polymeric acid to a polymeric acid, the concentration of the acid used must be adjusted.

This is not industrially preferable because it requires an increase in capacity and the cost becomes very high.

[Means for solving problems]

In view of the above, the present invention is an extremely efficient polymeric acid that can recover polymeric acids from polymeric acid salts at high conversion rates and yields, and that can also regenerate and reuse used waste acids. The present invention provides a method for manufacturing.

That is, in the present invention, when liberating a salt of a water-soluble polymeric acid and obtaining the polymeric acid, the water-soluble polymeric acid is obtained by using an electrodialysis apparatus in which amphoteric ion exchange membranes and cation exchange membranes are arranged alternately. Kobo (A) for obtaining a polymeric acid by liberating an acid salt;
Next, a solution (
B), Step 1: Regenerating the neutralized solution into acid and alkali using an electrodialysis device equipped with a bipolar membrane, +1m ion exchange membrane, and cation exchange membrane. Consisting of (C),
This method of producing a polymeric acid is characterized in that this regeneration is used as a source of obtaining a polymeric acid, and a part of the regenerated alkali is reused as a neutralizing liquid.

The salt of the water-soluble polymeric acid used in the present invention has a salt in the molecule, for example, a carboxylic acid group, a sulfonic acid group, or a phosphoric acid group.

It is a polymer having acid groups such as sulfate groups. For example, sodium alginate obtained from nature, or a polymerizable monomer having an acid group as described above, may be partially or completely KNa before or after polymerization.

These include water-soluble polymeric acid salts in the form of salts of K, Ca, Ba, etc.

Examples of polymers having carboxylic acid groups as described above include acrylic acid and methacrylic acid.

It is a polymer of monomers such as maleic acid, 7-malic acid, and itaconic acid. Examples of polymers containing sulfonic acid include vinyl sulfonic acid.

It is a polymer of monomers such as p-styrene sulfonic acid and 2-hydroxy-3-7 lyloxypyl sulfonic acid. Examples of polymers having phosphoric acid groups include mono(2-hydroxyethyl methacrylate), mono(3chloro-2
It is a polymer of monomers such as -hydroxypropyl methacrylate) and 7-side phosphate. Examples of polymers having sulfate groups include polymers of monomers such as 7lyl sulfate and esters. In addition, monomers that can be polymerized with monomers having these acid groups, such as acrylic esters,
Methacrylic acid ester, 7-crylonitrile, methacrylonitrile, styrene.

Examples include copolymers with α-methylstyrene, vinyl acetate, acrylic 7ζ-do, N-methyl 7-acryl 7mide, NN'-dimethyl, aminoethyl methacrylate, and the like.

The amphoteric ion exchange membrane used in step (A) of the present invention is:
It has a uniform mixture of cation exchange groups and hard ion exchange groups.For example, conventionally known sulfonic acid and carboxylic acid groups are suitable as cation exchange groups, and quaternary groups are suitable as anion exchange groups. Onium bases such as quaternary pyridinium bases, sulfonitum bases, and phosphonium bases, which are class heptammonium bases, and weak bases such as primary, secondary, 1g, and tertiary amino groups are preferably used. These amphoteric ion exchange membranes are so-called hydrogen ion selectively permeable membranes, and any conventionally known membranes having this property can be used. Further, as the cation exchange membrane, a membrane that selectively allows only cations to permeate, and generally known membranes having sulfonic acid groups, carboxylic acid groups, etc., can be used.

In addition, the cation exchange membrane to be combined with the electrodialysis apparatus using a bipolar membrane in step (C) must be a monovalent selective cation exchange membrane having an anion exchange base layer on at least one surface of the cation exchange membrane. is preferred.

The anion exchange membrane used in step (C) of the present invention may be any conventionally known anion exchange membrane that selectively allows anions to pass therethrough, but weakly basic anion exchange membranes are particularly preferred. . Furthermore, bipolar membranes are composite membranes that have a cation exchange base layer on one side and an anion exchange base layer on the other, and in particular, the cation exchange base layer accounts for 10% to 60% of the total membrane thickness. Any conventionally known membranes such as bipolar membranes, composite ion exchange membranes, and amphoteric membranes can be used as long as they have the same properties.

The dialysis conditions of the electrodialysis tank configured by alternately arranging amphoteric ion exchange membranes and cation exchange membranes in step (A) of the present invention are preferably a current density of 110. S ~20 A/
d7FLs, a polymer wave can be produced at a high conversion rate by electrodialysis at a temperature of Fl 1o to 5°C. In addition, by double decomposition of the neutral salt in step (C), it is possible to generate highly concentrated acids and alkalis with higher current efficiency than by performing electrodialysis under the same conditions in an electrodialysis tank that regenerates acids and alkalis. Can be done.

The strong acids used in the production process of the polymeric acid of the present invention include:
Generally known organic or inorganic strong acids are used, such as sulfuric acid,
These include nitric acid and furkylsulfonic acid.

The method of the present invention will be explained based on the drawings. However, the drawings show only one example of the apparatus used in the method of the present invention, and the present invention is not limited thereby.

(A) The electrodialysis tank 1 in the step is a cation exchange membrane 15
and an amphoteric ion exchange membrane 16 into a polymeric acid chamber 7 and an acid chamber 8.

The water-soluble polymeric acid salt 4 described above is supplied to the chamber 7, and the acid 1
4 is supplied to chamber 8. And the amphoteric ion exchange membrane 16
Only the cod is passed through, and the water-soluble polymeric acid salt is converted into polymeric acid 5 at a high conversion rate and recovered. On the other hand, the liberated salt passes through the cation exchange membrane 15 and becomes a neutral salt.
A mixture 6 of neutral salt and low concentration acid is discharged from the chamber 7. This discharged liquid 6 is supplied to the neutralization tank 3 in step (B), and is neutralized with an alkali 13 such as sodium hydroxide or potassium hydroxide to become a neutral salt. This neutral salt aqueous solution 9 is supplied to the intermediate chamber 12e'C of the electrodialysis apparatus 2 in step (C). In addition, what is necessary is just to implement the neutralization process (B) with the well-known neutralizer 9 using the existing neutralization apparatus.

The electrodialysis apparatus 2 is divided into three chambers, an intermediate chamber 12, an acid generation chamber 10, and a potassium generation chamber 11, by a bipolar membrane 18, an anion exchange membrane 1, and a cation exchange membrane 19. An aqueous solution 9 of neutral salts is fed into an intermediate chamber 12 . Then, the cations pass through the cation exchange membrane 19, and the bipolar membrane 18
It combines with the hydroxyl groups generated from the above to form caustic alkali. In addition, the negative ions pass through the anion exchange membrane 17 and become bipolar B! It combines with H+ generated from X18 to become an acid. The regenerated acid 14 is supplied to the chamber 8 of the electrodialysis cell 1 and is used as an acid for converting a salt of a water-soluble polymeric acid into the polymeric acid. On the other hand, the regenerated alkali 13 is used in the neutralization step (B) K
Used as a neutralizing agent.

Example 1 A 20% sodium polyacrylate aqueous solution (Na classification 58111> shown in Figure 1) obtained by polymerizing a sodium acrylate aqueous solution and an ammonium persulfate aqueous solution was treated according to the sheet, and polyacrylic acid, acid and alkali were Collection was carried out.

(A) Neo Shichibuta CS is used as an electrodialysis tank in the process.
V, an electrodialysis tank TS-2 divided into polymer acid-rich and acid-rich areas using 9 amphoteric ion exchange membranes and 1 strong cation exchange membrane made by Neo Nanbuta CM (Tatsu@Tokuyama, respectively)! ml (manufactured by Tokuyama Soda@); effective membrane area 26 d/pair) was used.

The electrodialysis tanks used in the regeneration process in the (C) process are Neo Jojibuta CMS and Neo Shichibuta ACM (Tokuyama Soda@); -Value selective cation exchange membrane 1 Weakly basic anion exchange membrane An electrodialysis tank (BPM (Tokuyama Soda@)) divided into an intermediate chamber, an acid generation chamber, and an alkali generation chamber (a bipolar membrane with a strongly acidic cation exchange group and a strongly basic anion exchange group) (Tokuyama 1) @) IIs s-chamber double decomposition tank, effective membrane area 2dd/pair) was used. Also,(
A neutralization sedimentation tank was provided as a neutralization device in the step B).

In the electrodialysis apparatus of step (A), a sodium polyacrylate aqueous solution (Na content 58 I!/l) with a polymerization rate of 20% is supplied as a water-soluble polymeric acid salt, and 3N sulfuric acid is supplied as a conversion device, and the average Dialysis was performed at a current density of 4 A/d at 27°C. As a result, the conversion rate from polyacrylic acid (7 um) to polyacrylic acid was 96%, and the H current efficiency was 99%. The waste liquid contained an acid and a neutral salt, and its concentration was 0.54N for sulfuric acid and 1.2N for the neutral salt. The waste liquid was supplied to a neutralization tank and first neutralized using sodium hydroxide. The neutralized filtrate is supplied to the intermediate chamber 12 of the electrodialysis tank in step (C) 11, and the temperature is 35°C.
Electrodialysis was performed at an average current density of 5 A/dm'.

As a result, a regenerated liquid containing 3.1 N of sulfuric acid and 3.0 N of sodium hydroxide was obtained.

This regenerated acid was then supplied to the acid form of the electrodialysis tank in step (A) and used as regenerated acid, and the regenerated alkali was used as a neutralizing agent in the neutralization step. “Example 2 Sodium polystyrene sulfonate aqueous solution (Na content 25
11/l) was treated according to sheet 7 in FIG. 1 to recover polystyrene sulfonic acid, acid, and alkali.

The electrodialysis method was performed under the same conditions and steps as in Example 1.

As a result, polystyrene sulfonic acid with a conversion rate of 98% was obtained, sulfuric acid was 3.2 N, sodium hydroxide was 3.1
Got the regulations.

[Brief explanation of the drawing]

FIG. 1 is a flow diagram showing a typical manufacturing method of the present invention. In Figure 1, 1 is an electrodialysis device for obtaining polymeric acid, 2 is an electrodialysis device for regenerating acid and alkali, 3 is a neutralization tank, 4 is a salt of polymeric acid, 5 is a polymeric acid, and 6 is a Waste acid and neutral salt, 9 indicates neutralized liquid, 13 indicates regenerated alkali IJ, 14 indicates regenerated acid, and in the electrodialyzer unit, 7 indicates high molecular acid chamber, and 8 indicates acid chamber. In the electrodialyzer 2, IO is an acid generation chamber, 11 is an alkali generation chamber, 12 is a desalination chamber, 15 is a cation exchange membrane, 16 is an amphoteric ion exchange membrane, and 17 is an anion exchange membrane. , 18 shows the flow of a bipolar membrane, and 19 shows the flow of a monovalent ion permeable cation exchange membrane.

Claims (4)

[Claims] (1) When liberating the salt of a water-soluble polymeric acid and obtaining the polymeric acid, the salt of the water-soluble polymeric acid is separated using an electrodialyzer equipped with alternating amphoteric ion exchange membranes and cation exchange membranes. Step (A) of liberating and obtaining a polymeric acid; then step (B) of neutralizing the liberated mixed solution of neutral salt and acid; A method for producing a polymeric acid, comprising a step (C) of regenerating it into an acid and an alkali using an electrodialysis device equipped with a membrane. (2) The method according to claim 1, wherein the acid regenerated from step (C) is used as the acid in step (A). (3) Part of the alkali regenerated from step (C) is transferred to step (
The method according to claim 1, which is used as a neutralizing solution in B). (4) Claim 1, wherein the water-soluble polymer acid salt is a polymer having a carboxylic acid, sulfonic acid, or phosphoric acid group partially or completely converted into a salt in the molecule. the method of.