JP3010433B2 - Purification method of ionic polymer compound - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for purifying an ionic polymer compound, and more particularly to a method for efficiently removing ionic low molecular weight impurities such as residual monomers from the ionic polymer compound. About the method.

[0002]

2. Description of the Related Art Generally, when a low molecular weight impurity is separated and removed from a polymer compound, it is often volatilized by evaporation. However, when the low molecular impurities are ionic, such as an electrolyte, they are often non-volatile, and in this case, this method cannot be applied. In addition, a method of extracting a polymer compound using another solvent different from the solvent of the polymer solution is also conceivable. However, it is difficult to select an appropriate solvent, and a large amount of the solvent is used. For this reason, the operation is complicated and is not practical because it is dangerous or requires a step of removing the residual solvent from the polymer compound after purification.

A method for removing low molecular weight impurities using an ultrafiltration membrane is disclosed in Japanese Patent Application Laid-Open No. 3-66705 and Japanese Patent Publication No. 7-59609. In these methods, the polymer compound and the low-molecular-weight impurity are separated from each other by the difference in molecular size between the polymer compound and the low-molecular-weight impurity. According to these methods, it is possible to reduce the residual low-molecular-weight impurity concentration to a predetermined value without using a further solvent other than the solvent for the polymer solution, but it requires a large amount of time for purification. There's a problem.

Japanese Patent Application Laid-Open No. 8-217802 discloses a method of removing low molecular weight compounds having a molecular weight of 10,000 or less and unreacted monomers by using an ionic polymer compound with an ultrafiltration membrane. . However, even in this method, a method of removing the polymer while concentrating the polymer concentration during the treatment from 1% by weight to about 5% by weight is exemplified. Remaining.

In addition to such a method, a method of removing low molecular weight impurities mainly composed of unreacted monomers from a cationic polymer compound by using an electrodialysis method is disclosed in Japanese Patent Publication No. 7-68.
No. 298. However, in this electrodialysis method, since a low molecular weight ionic substance is removed by passing an electric current, the concentration of the low molecular weight ionic substance is 0.1%.
%, The current that can flow becomes extremely small, so that much time is required for purification.

[0006]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a low-molecular-weight compound having the same sign as the ionic polymer compound such as an ionic residual monomer in a shorter time from the ionic polymer compound. An object of the present invention is to provide a method for purifying an ionic polymer compound that efficiently removes impurities.

[0007]

The inventors of the present invention have studied and found that low molecular weight impurities, such as ionic polymer compounds and ionic residual monomers, charged to the same sign as the ionic polymer compound are contained. The aqueous solution to be prepared is prepared under the conditions that the concentration of the ionic polymer compound is 7 to 20% by weight and the charge amount of the ionic polymer compound in the aqueous solution is 0.30 g equivalent / L or more.
It has been found that the use of an ultrafiltration membrane and / or a reverse osmosis membrane makes it possible to efficiently remove low-molecular-weight impurities having a common counterion with the ionic polymer compound, thereby completing the present invention. Reached.

That is, the gist of the present invention is to provide (1) an aqueous solution containing an ionic polymer compound and a low-molecular-weight impurity charged to the same sign as the ionic polymer compound such as an ionic residual monomer. , The concentration of the ionic polymer compound is 7 to
Removal of the low molecular weight impurities using an ultrafiltration membrane and / or a reverse osmosis membrane under the condition that the amount of the ionic polymer compound in the aqueous solution is 20% by weight and the charge amount of the ionic polymer compound is 0.30 g equivalent / L or more. A method for purifying an ionic polymer compound,
(2) The ionic polymer compound has a charge amount of 3.0 g.
(1) The method for purifying an ionic polymer compound according to the above (1), wherein the solvent is 60% by weight or more of water constituting the aqueous solution. (1) The method for purifying an ionic polymer compound according to (1) or (2), (4) wherein the ultrafiltration membrane or the reverse osmosis membrane is a ceramic filter.
(3) The method for purifying an ionic polymer compound according to any one of (5), wherein the average pore diameter of the ultrafiltration membrane or the reverse osmosis membrane is 4
(1) to (1)
(4) The method for purifying an ionic polymer compound according to any one of (6) and (6), wherein the ionic polymer compound has a weight average molecular weight of 5,000 or more and a low molecular weight impurity has a molecular weight of 500 or less. (1) The method for purifying an ionic polymer compound according to any one of (1) to (5), (7) the method according to any one of (1) to (6), wherein the ionic polymer compound is a cationic polymer compound. (8) The method for purifying an ionic polymer compound according to the above (1) to (7).
After purifying the ionic polymer using any of the purification methods described above, a method for purifying the ionic polymer, further comprising contacting the ionic polymer with an ionic exchange resin, About.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The ionic polymer compound used in the present invention will be described below. The dissociating group of the ionic polymer compound is not particularly limited as long as it forms a salt in the presence of an acid or a base, and may be any of anionic, cationic, or zwitterionic groups. For example, in the production of a cationic polymer compound, a cationic monomer having an odor often remains in many cases, and is suitably applied to a cationic polymer compound from the viewpoint of improving the odor. Specific examples of such a salt-forming group include a carboxyl group, a sulfonic acid residue, a sulfuric acid residue, a phosphoric acid residue, a nitric acid residue, an amino group, and an ammonium group. One or more of these groups may be contained in one compound.

Specific examples of such high molecular compounds include, for example, mucopolysaccharides such as hyaluronic acid and hyaluronic acid N
a, Na chondroitin sulfate; natural or semi-synthetic ones such as hemicelluloses such as alginic acid, sodium alginate, ammonium alginate, sodium carboxymethylcellulose, and carboxymethylamylose, and the like, but synthetic ones are more preferable. Examples of the synthetic system include those obtained by polymerizing one or more of the following monomers or (meth) acrylic acid such as a vinyl ester of an aliphatic carboxylic acid such as vinyl acetate and methyl methacrylate. Esters, alkyl vinyl ethers such as methyl vinyl ether, N-vinyl cyclic amides such as N-vinyl pyrrolidone, copolymers with other general monomers having no salt-forming group such as styrene and alkyl-substituted styrene, and polymers thereof And mixtures thereof.

The following monomers are exemplified as the anionic monomer. Unsaturated carboxylic acid monomers such as acrylic acid (AA), methacrylic acid (MA), maleic acid, itaconic acid, etc. or their anhydrides or salts thereof; styrenesulfonic acid, 2-acrylamide-2-methylpropanesulfonic acid (AMPS) ) And unsaturated phosphoric acid monomers such as vinyl phosphonic acid and acid phosphoxyethyl (meth) acrylate.

The following monomers are exemplified as the cationic monomer. (Meth) acrylate or (meth) acrylate having a dialkylamino group such as dimethylaminoethyl acrylate (DMAEA), dimethylaminoethyl methacrylate (DMAEMA), dimethylaminopropyl acrylamide (DMAPAAm), and dimethylaminopropyl methacrylamide (DMAPMAAAm)
Acrylamides; dimethylaminostyrene (DMAS
t), dimethylaminomethylstyrene (DMAMSt)
Styrenes having a dialkylamino group such as styrene; vinylpyridines such as 4-vinylpyridine and 2-vinylpyridine; or known quaternary compounds such as alkyl halide, benzyl halide, alkyl or aryl sulfonic acid, and dialkyl sulfate. Quaternized using an agent.

The following monomers are exemplified as the amphoteric monomer. N- (3-sulfopropyl) -N-
Acryloyloxyethyl-N, N-dimethylammonium betaine, N- (3-sulfopropyl) -N-methacryloylamidopropyl-N, N-dimethylammonium betaine, N- (3-carboxymethyl) -N-methacryloylamide Propyl-N, N-dimethylammonium betaine, N- (3-sulfopropyl) -N-methacryloyloxyethyl-N, N-dimethylammonium betaine, N-carboxymethyl-N-methacryloyloxyethyl-N, N-dimethylammonium Betaine.

When the salt-forming group of these polymer compounds is not ionized, an existing acid such as hydrochloric acid,
Inorganic acids such as sulfuric acid; organic acids such as acetic acid, propionic acid, lactic acid, succinic acid, and glycolic acid; or tertiary amines such as bases such as trimethylamine and triethylamine; What ionized the salt formation group of a molecular compound can be used.

The concentration of the ionic polymer compound in the aqueous solution according to the present invention is preferably 7 to 20% by weight, more preferably 9 to 20% by weight.
-18% by weight, particularly preferably 10-15% by weight. If the concentration of the ionic polymer compound is too low than 7% by weight, the amount of the ionic polymer compound that can be treated per unit purification time decreases. On the other hand, if it exceeds 20% by weight, it is possible to purify with a small amount of filtrate. However, since the viscosity becomes too high, the amount of filtrate permeating decreases and the purification time becomes longer. Further, the charge amount of the ionic polymer compound in the aqueous solution is desirably 0.30 g equivalent / L or more, more preferably 0.4 g equivalent / L or more, and particularly preferably 0.5 g equivalent / L or more. If the charge amount in the treatment aqueous solution is smaller than 0.30 g equivalent / L, it is considered that the action mechanism of the purification method described later does not function sufficiently,
Low molecular weight impurities are not efficiently removed.

The charge per unit weight of the ionic polymer compound itself is preferably at least 3.0 g equivalent / kg, more preferably at least 5.0 g equivalent / kg. When the charge amount of the ionic polymer compound itself decreases,
The effect of the present invention may not be sufficiently obtained.

The weight average molecular weight of the ionic polymer compound used in the present invention is desirably about 5,000 to 1.5 million. If it is less than 5000, it becomes difficult to separate low molecular weight impurities by the membrane. On the other hand, if it exceeds 1.5 million, the viscosity of the aqueous solution containing the ionic polymer compound becomes too high, so that the amount of the permeated liquid of the aqueous solution decreases, and as a result, it takes a lot of time for purification.

The ultrafiltration membrane or reverse osmosis membrane used in the present invention is capable of separating low molecular weight impurities such as residual monomers substantially and not ionic high molecular compounds, but separating them. It is possible to select a membrane having an optimum average pore diameter according to the molecular weight of the ionic polymer compound to be separated. Preferably 4
A membrane having an average pore size of from 100 to 100 nm, particularly preferably from 10 to 50 nm, is used. If the average pore diameter is too small, the permeation of low molecular weight impurities may be hindered, and the amount of permeate per unit area may decrease. On the other hand, if the average pore diameter is too large, the permeation inhibition rate of the ionic polymer compound decreases. For this purpose, a film that meets the above conditions can be arbitrarily selected from commercially available films. When the weight average molecular weight of the ionic polymer compound used in the present invention is 10,000 or more, an ultrafiltration membrane can be suitably used, and when it is less than 10,000, a reverse osmosis membrane can be suitably used.

The ultrafiltration membrane in the present invention has fine pores and is capable of transmitting low molecular weight impurity molecules charged to the same sign as the ionic polymer compound such as ionic residual monomer. Anything can be used without particular limitation. Examples of a material for forming such an ultrafiltration membrane include organic polymer compounds such as polyethersulfone, polysulfone, polyvinyl alcohol, polyamide, polyvinylidene fluoride, and polytetrafluoroethylene, and porous glass and ceramics. Inorganic materials can be given.

Reverse osmosis membranes have been originally used for separating inorganic ions such as desalination of seawater and desalination of industrial water by preventing permeation of low molecular compounds such as NaCl. As a reverse osmosis membrane used for such a purpose of desalination, N
Although a film having an aCl permeation rejection of 95% or more has been used, a film having a NaCl permeation rejection of 10 to 50% has recently been put on the market. This membrane is characterized in that it allows low molecular compounds such as salts to permeate, but does not allow a certain amount of high molecular compounds to permeate. That is, the permeation inhibition rate of NaCl is 1
When a reverse osmosis membrane having a concentration of 0 to 50% is used, it is possible to separate an ionic high molecular compound from an ionic low molecular compound. As a material for forming such a reverse osmosis membrane, for example, polysulfone, polyvinyl alcohol, cellulose acetate and the like are used. As a reverse osmosis membrane having such a permeation inhibition rate, SU-600 (Toray Industries, Inc.)
NTR1550 (manufactured by Nitto Denko Corporation, trade name) and the like.

The separation device equipped with the ultrafiltration membrane or reverse osmosis membrane may be of any type, whether ultrafiltration or reverse osmosis, and may be a flat membrane type, a spiral type, a tubular type, or a follow-up type. Each device such as a fiber type and a vibration type can be applied. At this time, the higher the permeation inhibition rate of the ionic polymer compound, the better. If a membrane with a small pore size is selected, the permeation rejection will increase, but on the contrary, the permeation flow rate will decrease, which may result in a longer purification time. In order to obtain a high permeation rejection and a large permeation flow rate, it is appropriate to use a membrane having a narrow pore size distribution. Therefore, it is generally preferable to use a ceramic filter having a sharp pore size distribution. The method for removing and purifying low molecular weight impurities using a membrane is not particularly limited, and examples thereof include a concentration method and a diafiltration method in which the same amount of water as the permeated filtrate is added. Further, a method of repeating concentration and dilution several times or a method combining a concentration method and a diafiltration method may be used. Among them, diafiltration is preferable because the ionic polymer compound concentration during the treatment can be maintained at an optimum concentration for purification.

The low molecular weight impurities such as residual monomers referred to in the present specification may be those which are charged to the same sign as the target ionic polymer compound, and are efficiently removed by the method of the present invention. be able to. Specific examples of such low molecular weight impurities include residual polymerizable monomers, oligomers having a low degree of polymerization, and salts of decomposition products of a polymerization initiator. The molecular weight of the low molecular weight impurities is desirably 500 or less. If the molecular weight is too high, it will be difficult to separate the ionic polymer compound and low molecular weight impurities by the membrane. Examples of the polymerization initiator include, for example, 2,2 ′
-Azobis (2-amidino-propane) dihydrochloride, 2,2'-azobis (2- (5-methyl-2-
Imidazolin-2-yl) propane) dihydrochloride, 2,2'-azobis (2- (2-imidazoline-
Azo-based water-soluble polymerization initiators such as 2-yl) dihydrochloride and 2,2′-azobis (2-methylbutanamidooxime) dihydrochloride, and polymerization initiators such as potassium persulfate, ammonium persulfate and sodium persulfate. And other common water-soluble polymerization initiators.

In the present invention, the ionic polymer compound purified as described above may be subjected to a contact treatment with an ion exchange resin for further purification. This makes it possible to efficiently remove low molecular weight impurities that have the same sign as the ionic polymer compound at a low concentration. As the ion exchange resin that can be used in the present invention,
Cation exchange resins and anion exchange resins are exemplified.
These may be used alone or in combination.

As the cation exchange resin, a strongly acidic cation exchange resin and a weakly acidic cation exchange resin can be used. As a strong acidic cation exchange resin, for example,
Resins having a sulfonic acid group as an exchange group are exemplified. Specific examples thereof include DIAION SK1B, SK104, SK110, SK112, and SK112 (trade names) manufactured by Mitsubishi Chemical Corporation.
K116, PK208, PK212, PK216, PK
220, PK228, HPK25, Amberlite IR-120B, IR-12 (trade name) manufactured by Organo Corporation
4, 200C, 201B, 252, IR-118 and the like. As a weakly acidic cation exchange resin, for example,
Examples thereof include methacrylic acid-based and acrylic acid-based ion exchange resins in which the exchange group is a carboxylic acid group, and specific examples thereof include Diaion WK1 (trade name) manufactured by Mitsubishi Chemical Corporation.
0, WK11, WK100, WK01S, WK40, Amberlite IRC-5 (trade name) manufactured by Organo Corporation
0, IRC-76 and the like. When the pH of the solution containing the ionic polymer compound is less than 8, it is desirable to use a strongly acidic cation exchange resin capable of performing ion exchange in the entire pH range. When the pH of the solution containing the ionic polymer compound is 8 or more, it is desirable to use a weakly acidic cation exchange resin having a large total ion exchange capacity and easy regeneration.

As the anion exchange resin, a strongly basic anion exchange resin and a weakly basic anion exchange resin can be used. Examples of the strongly basic anion exchange resin include a resin having a quaternary ammonium group as an exchange group, and specific examples thereof include Diaion SA10A, SA11A, and SA12 (trade names) manufactured by Mitsubishi Chemical Corporation.
A, NSA100, SA20A, SA21A, PA30
8, PA312, PA316, PA408, PA41
2, PA418, HPA25, HPA75, Amberlite IRA-400, trade name, manufactured by Organo Corporation
RA-400T, IRA-401, IRA-402, I
RA-402BL, IRA-410, IRA-411
S, IRA-440B, IRA-458, IRA-90
0, IRA-904, IRA-910, IRA-958
And the like. Examples of the weakly basic ion exchange resin include resins in which the exchange group is a primary to tertiary amine, and specific examples thereof include Diaion WA10, WA20, and WA21J (trade names) manufactured by Mitsubishi Chemical Corporation. , WA3
0, Amberlite IRA (trade name) manufactured by Organo Corporation
-35, IRA-60E, IRA-68, IRA-93
ZU, IRA-94S and the like.

When the pH of the solution containing the ionic polymer compound is 5 or more, it is preferable to use a strongly basic anion exchange resin capable of performing ion exchange in the whole pH range. When the pH of the solution containing the ionic polymer compound is less than 5, it is desirable to use a weakly basic anion exchange resin having a large total ion exchange capacity and easy regeneration.

In the present invention, when the ion-exchange resin is not regenerated when the ion-exchange resin is used, the ion-exchange resin is used after performing a generally performed regeneration treatment. That is, in the case of a cation exchange resin,
Non-H type, for example, Na type, use hydrochloric acid or sulfuric acid aqueous solution before use, and in the case of anion exchange resin, non-OH type, for example, Cl type,
Before use, each ion exchange resin is treated in a container filled with each ion exchange resin using an aqueous sodium hydroxide solution, and then washed with demineralized water to regenerate each ion exchange resin.

In the present invention, when the regenerated ion exchange resin is used, any of a batch method and a column method may be used according to the purpose. As for the use conditions, in the batch method, a cation- or anion-exchange resin having an exchange group amount of 1 equivalent or more is added to the ionic impurities contained in the polymer solution. To remove the ion exchange resin. In the case of the column type, either the circulation method or the circulation method may be used. Although the flow rate is not particularly limited, for example, in the circulation method, the space velocity (= (flow rate m ³
/ Time) / (resin amount m ³⁾⁾ in 1 Hr ^-1 or more conditions, also it is preferable to set the flow rate and ion exchange resin amount 100 Hr ^-1 following conditions at flow method. Further, in consideration of the strength of the ion exchange resin, a flow rate at which the differential pressure of the resin layer can be operated at a differential pressure of 1 MPa or less within the above space velocity range is desirable. The column capacity is determined by resin swelling and shrinkage and resin regeneration,
In consideration of the washing operation, the volume is preferably 1.2 to 5 times the resin volume.

As a method of using a cation exchange resin and an anion exchange resin in combination, a mixed bed purification method in which they are mixed, a purification method in which each is filled in a separate container or column, and the like, is used. Is raised.

In the present invention, the solution containing the ionic polymer compound and the low-molecular-weight impurity to be purified is an aqueous solution and water is used as a solvent, but does not prevent dissociation of the ionic polymer compound and the low-molecular-weight impurity. It may contain a small amount of an organic solvent such as methanol, ethanol, isopropyl alcohol, and acetone. However, even when an organic solvent other than water is contained, the proportion of water in the solvent is preferably at least 60% by weight, particularly preferably at least 80% by weight. When the content of water in the solvent is less than 60% by weight, the degree of dissociation of the ionic polymer compound is reduced, so that the amount of charge in the aqueous solution of the ionic polymer compound to be treated is reduced, and the effect of the present invention is reduced. Is not sufficiently obtained. When the degree of dissociation of the ionic polymer compound varies depending on the pH, it is desirable to adjust the pH so that the degree of dissociation becomes higher.

The mechanism of action of the purification method of the present invention is not clear, but is presumed as follows. That is, it is generally considered that a low-molecular compound that can permeate a membrane permeates at the same concentration as the mother liquor (treatment liquid) side. But as in this application,
If an ionic polymer compound that cannot pass through the membrane is present in the aqueous solution, and the counter ion of the ionic polymer compound can pass through the membrane, the counter ion of the ionic polymer compound will also be in the mother liquor ( Attempts to permeate the membrane at the same concentration as the (processing solution) side. Since the electrical neutrality must be maintained in an aqueous solution, the high molecular compound serving as the ion pair must simultaneously pass therethrough. However, since the high molecular compound cannot pass through the membrane as described above, as a result, a low molecular compound that is permeable through the membrane and has the same charge as the high molecular compound permeates. As a result, it is considered that the low molecular compound permeates at a higher concentration than when permeating the membrane surface alone. Based on this consideration, it is presumed that the effects of the present invention become more pronounced as the concentration of the ionic polymer compound is higher and the counterion concentration of the ionic polymer compound is higher.

[0032]

The present invention will be described in more detail with reference to the following Examples and Comparative Examples, but the present invention is not limited to these Examples and the like.

Example 1 An 18% by weight aqueous solution of cationic polymethacryloyloxyethyltrimethylammonium chloride was obtained by a polymerization reaction. The charge per unit weight of the ionic polymer compound was 4.81 g equivalent / kg. At this time, the weight average molecular weight of the ionic polymer compound was 220,000. The weight concentration of the residual monomer per solid is 1260p
pm. The molecular weight of the remaining monomer was 207.7. The weight concentration of the remaining monomer was measured by a liquid chromatography method. 10 kg of this aqueous solution was added with 5 kg of ion-exchanged water to form a 12% by weight aqueous solution, and the solution was placed in a ceramic filter (manufactured by Toshiba Ceramics Corp., trade name: MEMBRALOX) ultrafiltration apparatus to purify the ionic polymer compound. went. The charge amount of the ionic polymer compound in the treatment aqueous solution was 0.58 g equivalent / L. The pore size of the ceramic filter was 10 nm, and the membrane area was 0.4 m ² .

The operating conditions were determined by a diafiltration filtration method in which the same amount of water as the permeated filtrate was charged. The circulation flow rate of the aqueous solution in the membrane was 1.2 m / s, the inlet pressure of the membrane module was 9.0 kgf / cm ² , Outlet pressure 6.5 kgf / cm
^{Was 2} . Table 1 shows the change over time in the concentration of the residual monomer per solid content and the amount of the integrated filtrate in the treatment aqueous solution at the time of purification.
Further, the residual monomer concentration per solid content in the treatment aqueous solution, which is theoretically calculated from the integrated filtrate amount, is shown for comparison. This theoretical calculation value is based on the following theoretical calculation formula used when purified by the diafiltration method. C = Co ・ e- ^{V / Vs,} where: V: integrated filtrate amount Vs: total amount of the treatment aqueous solution C: residual monomer concentration in the treatment solution at the accumulated filtrate amount V Co: residual single amount in the initial treatment solution Represents body concentration.

[0035]

[Table 1]

Example 2 10 kg of an aqueous 18% by weight aqueous solution of poly (methacryloyloxyethyltrimethylammonium chloride) and 10 k of ion-exchanged water
Purification was performed in the same manner as in Example 1 except that g was added to obtain a 9% by weight aqueous solution. At this time, the charge amount of the ionic polymer compound in the treatment aqueous solution was 0.43 g equivalent / L. Table 2 shows the results.

[0037]

[Table 2]

Example 3 2 kg of ion-exchanged water was added to 10 kg of an aqueous 18% by weight polymethacryloyloxyethyltrimethylammonium chloride solution.
Was performed in the same manner as in Example 1 except that a 15% by weight aqueous solution was added. At this time, the charge amount of the ionic polymer compound in the treatment aqueous solution was 0.72 g equivalent / L.
Table 3 shows the results.

[0039]

[Table 3]

Example 4 1.2 L of a treated aqueous solution (15 kg of a 12% by weight aqueous solution, a residual monomer concentration of 358 ppm per solid, pH 5.6) obtained in the same manner as in Example 1 and obtained after 2 hours of purification was used. Strongly acidic cation exchange resin (SK1B: manufactured by Mitsubishi Chemical Corporation)
A column (diameter 70 mm, length 780 mm) packed with is flowed at a flow rate (space velocity 1) of 15 kg / hour (liquid specific gravity 1.01).
(2.4 Hr ^-1 ). The residual monomer concentration per solid content in the obtained treatment aqueous solution was 29 ppm.

Example 5 The treated aqueous solution (purity 3 hours, 20 kg, residual monomer concentration 298 ppm per solid, pH 5.7) obtained after 3 hours of purification obtained in the same manner as in Example 2 was used in the same manner as in Example 4. 20 kg flow rate into a column packed with ion exchange resin
/ Hr (space velocity: 16.5 Hr ^-1 ). The residual monomer concentration per solid content in the obtained treatment aqueous solution is 31.
ppm.

Example 6 The treated aqueous solution (12 kg of 15% by weight aqueous solution, residual monomer concentration per solid content of 430 ppm, pH 5.5) obtained in the same manner as in Example 3 and obtained after 2 hours of purification was the same as in Example 4. 12 kg /
The solution was passed at a time flow rate (space velocity of 9.9 Hr ^-1 ). The residual monomer concentration per solid content in the obtained treatment aqueous solution is
It was 30 ppm.

Comparative Example Polyvinyl methacryloyloxyethyltrimethylammonium chloride (10 kg) was added to 10 kg aqueous solution and ion-exchanged water (35 k)
g in the same manner as in Example 1 except that a 4% by weight aqueous solution was added. At this time, the charge amount of the ionic polymer compound in the treatment aqueous solution was 0.19 g equivalent / L.
Table 4 shows the results.

[0044]

[Table 4]

As is clear from Tables 1 to 4, Examples 1 to
In No. 3, it can be seen that the residual monomer concentration in the treatment aqueous solution obtained is much lower than the theoretically calculated value, and the residual monomer in the treatment aqueous solution is efficiently removed in a short time. On the other hand, when the concentration of the ionic polymer compound in the aqueous solution is low and the charge amount is lower than 0.30 g equivalent / L as in the comparative example, the residual monomer concentration of the obtained treatment aqueous solution is different from the theoretically calculated value. It was almost the same, and the effect of the present invention was not recognized. Also, from the results of Examples 4 to 6, Examples 1 to 3
Each of the treatment aqueous solutions obtained in step (a) is passed through a column filled with a strongly acidic cation exchange resin, and is subjected to contact treatment with the ion exchange resin, whereby the residual monomer concentration per solid component in each treatment aqueous solution is reduced. It can be seen that the residual monomer was further reduced and the residual monomer was efficiently removed.

[0046]

According to the method for purifying an ionic polymer of the present invention, low molecular weight impurities such as the ionic polymer and ionic residual monomers which are charged to the same sign as the ionic polymer are contained. Purification of an aqueous solution using an ultrafiltration membrane and / or a reverse osmosis membrane under predetermined conditions, thereby effectively removing and purifying low molecular weight impurities from an ionic polymer compound in a shorter time than before. Is played.

Continuing from the front page (72) Inventor Takashi Nojiri 1334 Minato, Wakayama City, Kao Corporation Research Laboratory (72) Inventor Shinobu Hiramatsu 1334 Minato, Wakayama City Kao Corporation Research Laboratory (56) References JP-A-8-217802 (JP, A) JP-A-5-97913 (JP, A) JP-A-7-25903 (JP, A) JP-A-3-66705 (JP, A) JP-B-7-59609 (JP, B2) ( 58) Field surveyed (Int.Cl. ⁷ , DB name) C08F 6/06

Claims (8)

(57) [Claims] An aqueous solution containing a low-molecular-weight impurity charged to the same sign as the ionic polymer compound, such as an ionic polymer compound and an ionic residual monomer, is dissolved in an aqueous solution containing the ionic polymer compound at a concentration of the ionic polymer compound. The low molecular weight impurities are removed using an ultrafiltration membrane and / or a reverse osmosis membrane under a condition of 7 to 20% by weight and a charge amount of the ionic polymer compound in the aqueous solution of 0.30 g equivalent / L or more. A method for purifying an ionic polymer compound, comprising: 2. The method for purifying an ionic polymer compound according to claim 1, wherein the charge amount of the ionic polymer compound is 3.0 g equivalent / kg or more. 3. The method for purifying an ionic polymer compound according to claim 1, wherein 60% by weight or more of the solvent constituting the aqueous solution is water. 4. The method for purifying an ionic polymer compound according to claim 1, wherein the ultrafiltration membrane or the reverse osmosis membrane is a ceramic filter. 5. The method for purifying an ionic polymer compound according to claim 1, wherein the ultrafiltration membrane or the reverse osmosis membrane has an average pore diameter of 4 to 100 nm. 6. The purification of an ionic polymer compound according to claim 1, wherein the weight average molecular weight of the ionic polymer compound is 5,000 or more, and the molecular weight of the low molecular weight impurities is 500 or less. Method. 7. The method for purifying an ionic polymer according to claim 1, wherein the ionic polymer is a cationic polymer. 8. After purifying the ionic polymer using the purification method according to claim 1, the ionic polymer is further subjected to contact treatment with an ion-exchange resin. A method for purifying an ionic polymer compound.