JPS63286405A - Method for purifying cationic water-soluble polymer - Google Patents

Abstract

PURPOSE:To carry out purification by an extremely simple method, by removing impurities consisting essentially of an unreacted monomer contained in an aqueous solution of a cationic water-soluble polymer prepared by a solution polymerization method using an ion exchange membrane electrodialytic method. CONSTITUTION:An aqueous solution of a cationic a water-soluble polymer (e.g. polyallylamine, polydimethylaminoethylmethacrylamide or dimethyldiallylammonium chloride) obtained by solution polymerizing a cationic monomer is purified by subjecting the solution to ion exchange membrane electrodialysis to remove impurities consisting essentially of the unreacted monomer. Thereby the unreacted monomer can be removed to about 0.1-0.3% and safety is increased without evaporating toxic gases, since heat is applied to the monomer.

Description

DETAILED DESCRIPTION OF THE INVENTION (I) Industrial Field of Application The present invention is directed to an aqueous solution of a cationic water-soluble polymer obtained by a solution polymerization reaction, whose main component is unreacted monomers. The present invention relates to a method for purifying a cationic water-soluble polymer by removing impurities by using an ion exchange membrane electrodialysis method.

(TI) Conventional technology For example, when producing polyallylamine by solution polymerizing a cationic monomer such as monoallylamine in water, the cationic monomer as a raw material is polymerized as a salt of an inorganic or organic acid. This is common. Therefore, impurities mainly composed of inorganic or organic IN acid salts of unpolymerized monomers remain in the water-soluble polymer aqueous solution after the polymerization reaction.

When producing various derivatives using polymers containing such impurities as raw materials, it is necessary to obtain high-purity polymers from which these impurities have been removed as much as possible, as the decrease in purity will cause a decrease in the yield of the derivatives. has been done.

However, since impurities mainly composed of unreacted monomers are generally highly toxic, product polymers must be handled with care, especially if these polymers need to be heated. There is a risk that the polymer will evaporate, and its handling is extremely complicated.

Conventionally, the method for removing impurities mainly composed of unreacted monomers is to neutralize the high molecular weight polymer solution containing the impurities with an inorganic or organic base after the polymerization reaction, and to remove the remaining impurities. There is a method of converting the cationic monomer into a volatile free state and then removing impurities mainly composed of the residual monomer by evaporation or the like. This method requires a large amount of neutralizing agent, and there is a risk of thermal denaturation of the polymerized polymer.
This method had drawbacks such as the need to take sufficient safety measures because the working environment deteriorated due to the evaporation of the proprietary monomer.

Another method is to precipitate the polymer using a reprecipitation solvent that precipitates only the polymer in the polymerization reaction solution, and then separate impurities mainly composed of monomers dissolved in the solvent. However, it is necessary to re-collect the solvent and filter the precipitate, making the operation complicated and requiring a large amount of operating cost. Furthermore, in recent years, research has been conducted on methods that use reverse osmosis membranes or ultrafiltration membranes to permeate and remove impurities along with low-molecular-weight polymers, and separation using gel filtration that sieves based on molecular size. It may be necessary to lower
Since the scale of the device becomes very large, industrial application is still under consideration.

In addition to the above-mentioned method of removing monomers, there are other methods that allow the raw material monomer to remain after the polymerization reaction, such as prolonging the polymerization time or increasing the amount of polymerization initiator or catalyst. It has also been proposed to perform operations such as applying high temperature and high pressure to complete the reaction. However, these methods also have the disadvantage that the operations themselves are complicated and require a large amount of cost.

(Ill) Problems to be Solved by the Invention The present invention aims to remove impurities mainly composed of monomers remaining in an aqueous solution of a cationic water-soluble polymer obtained by solution polymerization of monomers. Disadvantages of conventional technology, part et al., neutralizing agent,
Requires auxiliary materials such as solvents, and requires complicated operations such as evaporation, solvent recovery, and precipitation filtration.Furthermore, there are concerns about operational safety due to evaporation of monomers when processing at high temperatures. This is an attempt to solve all the problems such as the fact that the In addition, in order to eliminate the uneconomical nature of conventional methods in which monomers do not remain after the reaction, the reaction is completed within an economical range, and the residual monomers are separated and recovered using an extremely simple method. Moreover, the separated and recovered residual monomer is intended to be reused as a raw material.

(rV) Means for Solving the Problems The present invention has been based on the conventional wisdom that when an aqueous solution of an ionic polymer is brought into contact with an ion exchange membrane, the polymer adheres to the membrane surface, causing membrane contamination. The above-mentioned problems were solved by using the ion exchange membrane electrodialysis method, which had not been used because of the conventional This method allows industrially very advantageous purification of cationic water-soluble polymers.

That is, in the present invention, an aqueous cationic water-soluble polymer solution obtained by solution polymerizing a cationic monomer is subjected to ion exchange lI electrodialysis to remove impurities mainly composed of unreacted monomers. This is a method for purifying a cationic water-soluble polymer, characterized by purification by removal.

The cationic water-soluble polymer to be used in the purification method of the present invention is obtained by solution polymerizing cationic monomers and is mainly composed of unreacted cationic polymers dissolved in water. This is an aqueous polymer solution containing impurities. The present invention can be used in any of these polymers and monomers that form acid salts, or in which these acid salts are completely or partially neutralized.

Such cationic water-soluble polymers include polyallylamine obtained by polymerizing monoallylamine, or polyallylamine hydrochloride and polyallylamine hydrobromide obtained by polymerizing an acid salt of monoallylamine. All homologs of are cationic water-soluble polymers referred to in the present invention. The present invention can also be applied to completely or partially neutralized products. A cross-linked polymer of polyallylamine using a cross-linking agent such as α, β-epoxy γ-halo alkane,
In addition, copolymers with diallylamine hydrochloride and triallylamine hydrochloride, polyN-alkyl substituted (meth)acrylamides such as polydimethylaminoethylmethacrylamide, polyN-furkyl substituted (meth)acrylamides such as polydiethylaminopropylacrylate, etc. The present invention is also applicable to homopolymers or copolymers of cationic water-soluble polymers such as meth)acrylic acid esters, N-alkyl-substituted diallylamines such as dimethyldiallylammonium chloride, polyvinylpyridine, and polyaminostyrene. I can do it.

An embodiment of the purification method using ion exchange membrane electrodialysis according to the present invention will be explained with reference to FIG. The battery container 9 is composed of a dilution chamber 3, a concentration chamber 4, and an electrode chamber 5, in which cation exchange membranes C and anion exchange membranes are arranged alternately in parallel, and are partitioned by the membranes. In the 1lri polar chamber 5 at both ends of
An anode and a cathode galvanic plate 6 are respectively provided. The cationic water-soluble polymer aqueous solution containing unreacted monomers put into the stock solution tank 1 is transferred to the dilution chamber 3 of the battery tank 9 by the pump P1.
sent to. Here, the unreacted monomer is "cation exchange W"
It moves to the concentration chamber 4 through AC, and the inorganic or organic acid forming the salt with the unreacted monomer or polymer exchanges anions! It passes through the lA membrane A and moves to the concentration chamber 4. At this time,
Cationic water-soluble polymers are cation exchange I! It is cut off by IC, and the water-soluble polymer from which unreacted monomers have been removed remains in the dilution chamber 3 as it is. On the other hand, the concentrated liquid tank 2 and the electrode chamber 5 are filled with an electrolytic solution of 1 to 2% concentration.
A NaCl solution or a Na2SO4 solution is generally used, but the present invention is not limited thereto, and any electrolyte solution may be used. This concentrated liquid is sent to the concentration chamber 4 by pump P2. Normally, a cationic polymer solution contains from several percent to more than ten percent of unreacted monomers based on the solid content, and the stock solution, concentrated solution, and electrode solution are divided into a dilution chamber, a concentration chamber, and a concentration chamber. By circulating the polymer solution to the electrode chamber and applying a DC voltage to the electrode plate 6, unreacted monomers are gradually removed by dialysis from the polymer aqueous solution containing unreacted monomers introduced into the stock solution tank 1. The unreacted monomers dialyzed into the concentrate are concentrated in the concentrate tank 2, and the purified polymer aqueous solution is finally in the concentrate tank 1, and the unreacted monomers are in the concentrate tank 2. The body becomes concentrated and stored.

In this way, a purified water-soluble polymer from which unreacted monomers have been removed can be obtained.

The cation exchange membrane and anion exchange membrane used in the present invention are general ion exchange membranes 11 (for example, C made by Asahi Glass Co., Ltd.).
MV, AMV, etc.), and there is no need to use a special ion exchange membrane. Furthermore, the electrodialysis tank to which these ion exchange membranes are attached may be commercially available, and there is no need to specially set the lI spacing, number of chambers, indoor permeation, etc.

(V) Actions and Effects By electrodialyzing an aqueous solution of a cationic water-soluble polymer, several percent to several tens of percent of unreacted monomers are removed based on the solid content contained in the solution. The body can be removed to the extent of 0.1% to 0.3%. As a result, it is no longer necessary to neutralize the polymerization reaction aqueous solution that has been commonly used so far and evaporate the monomers into a free state, so in the case of the purification method of the present invention, the monomer Since no heat is applied to the body, toxic gases do not evaporate, increasing safety, and the single-mouthed body can now be removed with an extremely simple process. Additionally, there is no need to use auxiliary materials such as neutralizers and solvents. The present invention has produced a number of effects, such as the fact that the unreacted monomer moves independently to the concentration chamber side of the electrodialysis tank, so it can be recovered and reused as a raw material. Furthermore, unlike in the past, there is no need to make extreme efforts to increase the polymerization rate without leaving unreacted monomers, and the polymerization reaction can be stopped at an economical point where unreacted monomers remain. , the processing of the present invention may be performed.

(Vl) Examples Representative examples of the present invention will be shown below, but the present invention is not limited thereto.

Example 1 An ou-ob tank manufactured by Asahi Glass Co., Ltd. was used as an electrodialysis device, and in this tank, 11 each of cation exchange membranes CMV and anion exchange membranes AMV, also manufactured by Asahi Glass, were arranged as shown in Figure 1. A dilution chamber 3, a concentration chamber 4 and an electrode chamber 5 are provided, and a stock solution tank 1,
A concentrated liquid tank 2 and circulation pumps P and P2 were installed. The self-effective membrane area of the ion exchange membrane is 0.188TrL2.

Stock solution 4f11 contains a 10% aqueous solution 3 of polyallylamine hydrochloride (weighted average molecular field 10,000, residual monomer concentration 9.93 weight percent based on solid content) as a stock solution.
．． 000g was prepared. In addition, the concentrated liquid tank 2 and the electrode chamber 5
Each was charged with 2000 grams of 1% NaCl solution.

When these solutions were circulated at a flow rate of 150 to 1601/Hr and a DC voltage of 16 to 17 volts was applied between the electrodes, after opening at 1.5 o'clock, the residual monomer in the stock solution was reduced to a solid content base. It was 0.3%, and the pH was 9.6.

Note that the analysis was performed by gas chromatography.

Example-2 The electrodialyzer, ion exchange membrane, attached equipment, operating conditions, etc. were completely the same as in Example-1, and as stock solutions, allylamine hydrochloride and diallylamine salt 111 salt were copolymerized at a molar ratio of 4:1. When an electrodialysis test was carried out using a 3% solution (containing 6.8 percent monomer on a solids basis) of the same product, it was possible to remove up to 0.09 percent monomer.

Example 3 Using the same equipment as in Example 1, an electrodialysis test was conducted using a 5% aqueous solution of a polymer of polydimethyldiallylammonium chloride (containing 3.5% as a monomer in terms of solid content) as a stock solution. As a result, it was possible to remove up to 0.3% of the monomer.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an electrodialysis apparatus used in the purification method of the present invention. 1: Stock solution tank, 2: Li condensation liquid tank, 3: Dilution chamber, 4: Concentration chamber, 5: Electrode chamber, 6: Electrode plate, 7: 11 Condensation liquid path, 8:1
1 condensation route, 9: electric tower, Pl, P2 nippon, A: anion exchange membrane, C: cation exchange membrane.

Claims (1)

[Claims] A cationic water-soluble polymer aqueous solution obtained by solution polymerization of a cationic monomer is purified by subjecting it to ion exchange membrane electrodialysis to remove impurities mainly composed of unreacted monomers. A method for purifying a cationic water-soluble polymer, characterized by: