JP6388329B2 - Water-soluble polymer dispersion containing low inorganic salt and process for producing the same - Google Patents

Description

The present invention relates to a water-soluble polymer dispersion in which an inorganic salt content is suppressed by a dispersion polymerization method in a salt aqueous solution in the presence of a polymer dispersant, and a method for producing the same.

Various patent publications disclose a technique of a dispersion liquid composed of an ionic water-soluble polymer in the presence of an ionic polymer dispersant in an aqueous salt solution. For example, Patent Document 1 discloses a method in which a cationic polymer soluble in an aqueous salt solution coexists as a dispersant when producing a dispersion in which the monomer is soluble in the aqueous salt solution and the polymerized polymer is insoluble. Is disclosed. Further, Patent Document 2 is a method in which a polyhydric alcohol such as ethylene glycol, propylene glycol, glycerin or polyethylene glycol is allowed to coexist when a dispersion comprising an anionic or cationic water-soluble polymer is produced. Furthermore, in Patent Document 3, when producing a dispersion composed of an anionic or cationic water-soluble polymer, the coexisting ionic polymer dispersant is composed of an anionic or cationic polymer that is soluble in an aqueous salt solution. Is disclosed. Various methods of using an additive as a thickening inhibitor during dispersion polymerization have also been disclosed (Patent Documents 4 and 5). It is described that the concentration of the salt constituting the salt aqueous solution used in these is at least 15% by mass. However, since these salts do not act as active ingredients and may inhibit the function of the polymer, there is a demand for less. In general, ammonium sulfate is widely used as an inorganic salt at the time of dispersion polymerization, but the total nitrogen content derived from the ammonium sulfate salt constituting the dispersion composed of the ionic water-soluble polymer used in these is 50,000 ppm (water-soluble) Polymer dispersion product) grade is included. Total nitrogen content has a great influence on crops. Plants absorb nitrogen in the form of ammonium nitrogen or nitrate nitrogen and use it for its growth. However, it is known that excessive nitrogen is adversely affected, and a reduction in the content is required. In addition, with the amendment of the Water Pollution Control Act of 2014, ammonium compounds have been designated as hazardous substances, and therefore there is a need for a dispersion polymerization solution that can reduce or reduce ammonium sulfate.

Japanese Patent Laid-Open No. 62-15251 JP 62-20502 A JP-A-62-20511 JP 2000-248209 A JP 2003-41135 A

An object of the present invention is to provide a water-soluble polymer dispersion in which an inorganic salt content is suppressed by a dispersion polymerization method in a salt aqueous solution in the presence of a polymer dispersant, and a method for producing the same.

As a result of intensive studies to solve the above problems, a monomer or monomer mixture containing a specific monomer as an essential component in a salt aqueous solution containing chloride ions and polyvalent anions is By carrying out dispersion polymerization in the presence of a molecular dispersant, it is possible to obtain a water-soluble polymer dispersion in which the inorganic salt content is suppressed.

  The water-soluble polymer dispersion in the present invention is a water-soluble polymer dispersion having a reduced inorganic salt content and a method for producing the same, and can exhibit the function of the polymer to the maximum and is released to the environment. Inhibition of salt-derived nitrogen content can be achieved.

The water-soluble polymer dispersion in the present invention contains a monomer or a monomer mixture aqueous solution containing a monomer represented by the following general formula (1) as an essential component in a salt aqueous solution. This is a water-soluble polymer dispersion obtained by coexisting a soluble polymer dispersant and dispersing polymerization with stirring.
General formula (1)
R ₁ is hydrogen or a methyl group, R ₂ and R ₃ are alkyl groups having 1 to ₃ carbon atoms, alkoxy groups, and R ₄ is an alkyl group or aryl group having 7 to 20 carbon atoms. A represents oxygen or NH, B represents an alkylene group or alkoxylene group having 2 to 4 carbon atoms, and X ₁ represents an anion.

The cationic monomer represented by the general formula (1) used for producing the water-soluble polymer dispersion in the present invention is a halogen such as dimethyl chloride of dimethylaminoethyl (meth) acrylate or dimethylaminopropylacrylamide. Cationized aryl compounds and quaternized products of alkyl halides having 7 to 20 carbon atoms. These cationic vinyl monomers can be used alone or in combination of two or more. You can also. Specific examples include (meth) acryloyloxyethyldimethylbenzylammonium chloride, (meth) acryloyloxy-2-hydroxypropylbenzyldimethylammonium chloride, (meth) acryloylaminopropyldimethylbenzylammonium chloride, and the like. The cationic monomer represented by the general formula (1) is preferably in the range of 5 to 100 mol%, more preferably 10 to 100 mol%.

A cationic monomer represented by the general formula (1) and a cationic monomer represented by the following general formula (2) used for producing the water-soluble polymer dispersion in the present invention are copolymerized. Can be used.

General formula (2)
R ₅ is hydrogen or a methyl group, R ₆ and R ₇ are alkyl or hydroxyalkyl groups having 1 to 3 carbon atoms, R ₈ is hydrogen and an alkyl group having 1 to 3 carbon atoms, A is oxygen or NH, B is represents an alkylene group having 2 to 4 carbon atoms, _{X 2} ^- represents respectively an anion.

Examples of the cationic monomer represented by the general formula (2) include dimethylaminoethyl (meth) acrylate, alkyl halides such as methyl chloride, and the like. It can also be used and it can also be used in combination of 2 or more types. Specific examples include quaternized products of dimethylaminoethyl (meth) acrylate or dimethylaminopropylacrylamide with a halide of a lower alkyl group such as methyl chloride or ethyl chloride. For example, (meth) acryloyloxyethyltrimethylammonium chloride, (meth) acryloyloxy-2-hydroxypropyltrimethylammonium chloride, (meth) acryloylaminopropyltrimethylammonium chloride, and the like.

Examples of the nonionic monomer used when the cationic monomer represented by the general formula (1) and the nonionic monomer are copolymerized include (meth) acrylamide, N, N-dimethylacrylamide, Examples include acrylonitrile, 2-hydroxyethyl (meth) acrylate, diacetone acrylamide, N-vinylpyrrolidone, N-vinylformamide, N-vinylacetamide, acryloylmorpholine, and the like. Two or more of these may be used in combination. Moreover, you may copolymerize the cationic monomer represented by General formula (1), the cationic monomer represented by General formula (2), and a nonionic monomer.

The water-soluble polymer dispersion in the present invention may be amphoteric in ionicity. In that case, an anionic monomer represented by the following general formula (3) is used at the time of production.
General formula (3)
R ₉ is hydrogen, methyl group or carboxymethyl group, Q is SO ₃ , C ₆ H ₄ SO ₃ , CONHC (CH ₃ ) ₂ CH ₂ SO ₃ , C ₆ H ₄ COO or COO, R ₁₀ is hydrogen or COOY ₂ , Y ₁ or Y ₂ each represents hydrogen or a cation.

The anionic monomer represented by the general formula (3) used when producing the amphoteric water-soluble polymer dispersion in the present invention is in the range of 0 to 40 mol%. Examples of anionic monomers include vinyl sulfonic acid, vinyl benzene sulfonic acid or 2-acrylamido-2-methylpropane sulfonic acid, methacrylic acid, acrylic acid, itaconic acid, maleic acid, phthalic acid or p-carboxystyrene acid Etc. Two or more of these may be used in combination. An anionic monomer and a nonionic monomer represented by the general formula (3) may be used, and an anionic monomer represented by the general formula (3) and the general formula (2) A cationic monomer and a nonionic monomer represented by

The salt water dispersion polymerization in the present invention can be produced by a conventional method disclosed in JP-A-62-215251, JP-A-62-25111, or JP-A-2007-16086. In the salt aqueous solution, a polymer dispersant containing diallyldimethylammonium chloride as a structural unit is coexisted in the salt aqueous solution, and a monomer containing the monomer represented by the general formula (1) as an essential component or The aqueous monomer mixture solution is subjected to dispersion polymerization. The water-soluble polymer obtained by containing the monomer represented by the general formula (1) as an essential component is difficult to dissolve in an aqueous salt solution due to the presence of a hydrophobic group such as a benzyl group in the general formula (1). It is suitable for dispersion polymerization. At the time of dispersion polymerization, by adding 0.5 to 5 mol% of a polymerization retarding substance with respect to all monomers, there is an effect of suppressing thickening, and it can be produced by appropriately adding. Examples of the polymerization retarding substance include itaconic acid, maleic acid, and phthalic acid.

In the present invention, the polymer dispersant used for the salt water dispersion polymerization is one containing diallyldimethylammonium chloride as a structural unit. Polydiallyldimethylammonium chloride may be used, but a copolymer of diallyldimethylammonium chloride and a nonionic monomer can also be used. Examples of nonionic monomers include acrylamide, N-vinylformamide, N-vinylacetamide, N-vinylpyrrolidone, N, N-dimethylacrylamide, acrylonitrile, diacetone acrylamide, 2-hydroxyethyl (meth) acrylate, etc. However, a copolymer with acrylamide is preferred. In addition, other cationic monomers such as (meth) acryloyloxyethyltrimethylammonium chloride may be contained in the polymer dispersant composition.

When the molecular weight of the polymer dispersant is high, the viscosity of the dispersion becomes high, which is not preferable. Therefore, it is 5,000 to 2,000,000, preferably 50,000 to 1,000,000. The addition rate of a polymer dispersing agent is 1-20 mass% with respect to a monomer, Preferably it is 5-20 mass%. The amount is preferably less than 5% by mass with respect to the dispersion. This is because containing 5% by mass or more is economically disadvantageous and may inhibit the function of the polymer.

As the inorganic salt used at the time of polymerization, a salt containing a chloride ion and a polyvalent anion is used. By using these two types of salts as essential, it is possible to produce a water-soluble polymer dispersion in which a large viscosity is suppressed and the total amount of inorganic salts is reduced. Examples of the salt containing chloride ions include sodium chloride, potassium chloride, calcium chloride and the like. As a salt containing a polyvalent anion, sodium sulfate and magnesium sulfate are preferable. The ratio of the chloride ion-containing salt to the polyvalent anion-containing salt is in the range of 1: 9 to 9: 1 by mass ratio, preferably 3: 7 to 7: 3. Alkali metal ions, halide ions, nitrate ions, phosphate ions, ammonium ions and the like other than these may also be included. The monomers are dissolved in these inorganic salt aqueous solutions, a polymer dispersant is further allowed to coexist, the pH is adjusted to 2 to 5, and after substitution with nitrogen, polymerization is initiated by a polymerization initiator.

When chloride ions and polyvalent anions are used in combination, the total amount of inorganic salts can be reduced, and the total amount of water-soluble polymer dispersion can be reduced to less than 15% by mass. Usually, a stable dispersion cannot be produced unless it is present in an amount of 20% by mass or more. This is because large thickening occurs during production. However, in the present invention, a polymer dispersing agent containing diallyldimethylammonium chloride as a structural unit is used, thickening is suppressed by using chloride ions and polyvalent anions in combination, and the total amount of inorganic salts is 15 mass. As a result, the present invention was found.

  Theoretically, there are many unclear points about the fact that the use of a polymeric dispersant containing diallyldimethylammonium chloride as a structural unit and the combined use of chloride ions and polyvalent anions has the effect of suppressing thickening. However, it is as follows when estimated from the phenomenon side. That is, as polymerization proceeds in an aqueous salt solution, the concentration of the produced polymer becomes higher than the solubility, and precipitation of polymer particles begins, but the polymer itself (polymerization system) because of the dissolved polymer before that. The viscosity of the polymer also increases, and the dissolved polymer and precipitated particles coexist. Thereafter, the ratio of the precipitated polymer increases, the viscosity of the polymer gradually decreases, and changes into a dispersed state. In this coexisting state, the slip between the precipitated particles and the gel-like dissolved polymer is improved, and the phase transition from the thickened state before the phase change to the dispersed state smoothly shifts. It is considered the main role. In the initial stage of polymerization, due to the action of diallyldimethylammonium chloride, which is a constituent unit of the dispersant, and chloride ions, it participates in the phase separation of the resulting polymer with a relatively low molecular weight, allowing the phase change to proceed smoothly. In the latter half of the process, it is considered that the polymer dispersion can be stably produced as a result of promoting the salting out effect of the produced polymer with a relatively high molecular weight by the action of the polyvalent anion having a strong salting out power.

In the present invention, an inorganic salt that does not act as an active ingredient and may inhibit the function of the polymer can be suppressed. In particular, ammonium sulfate is preferably used as the inorganic salt of the water-soluble polymer dispersion, but the total nitrogen content derived from the ammonium sulfate salt is about 50,000 ppm (for water-soluble polymer dispersion products). ing. By eliminating the nitrogen derived from the ammonium sulfate salt, the total nitrogen content can be reduced to less than 30000 ppm (for a water-soluble polymer dispersion product). Total nitrogen content has a great influence on crops. Plants absorb nitrogen in the form of ammonium nitrogen or nitrate nitrogen and are used for its growth. However, it is known that excessive nitrogen causes adverse effects, and a reduction in the content is required. In addition, since the ammonium compound is designated as a hazardous substance in accordance with the revision of the Water Pollution Control Law in 2014, there is a concern about the impact on the environment. The water-soluble polymer dispersion of the present invention has a total amount of inorganic salts. Since it can be suppressed to less than 15% by mass, the influence on the environment can be greatly reduced.

The polymerization concentration is 10% by mass to 35% by mass as the monomer concentration, and preferably 15% by mass to 30% by mass. This is because the higher the monomer concentration, the more economically advantageous due to the problem of transportation costs. However, if the monomer concentration exceeds 35% by mass, the viscosity increases during production and it becomes difficult to obtain a dispersion. is there. As a monomer supply method, it may be charged all at once at the start of polymerization, or may be charged in an appropriate manner.

The polymerization conditions are usually determined appropriately depending on the monomers used and the copolymerization mol%, and the temperature is in the range of 0 to 100 ° C. For the initiation of polymerization, a radical polymerization initiator is used. These initiators may be either oil-soluble or water-soluble, and can be polymerized by any of azo, peroxide, and redox systems. Examples of oil-soluble azo initiators are 2,2′-azobisisobutyronitrile, 1,1′-azobis (cyclohexanecarbonitrile), 2,2′-azobis (2-methylbutyronitrile), 2,2′-azobis (2-methylpropionate), 4,4-azobis (4-methoxy-2,4dimethyl) valeronitrile, and the like are mentioned, which are dissolved in a water-miscible solvent and added.

Examples of water-soluble azo initiators include 2,2′-azobis [2- (2-imidazolin-2-yl) propane] dihydrochloride, 2,2′-azobis [2- (2-amidinopropane) And dihydrochloride, 4,4′-azobis (4-cyanovaleric acid), and the like. Examples of the redox system include a combination of ammonium peroxodisulfate and sodium sulfite, sodium bisulfite, trimethylamine, tetramethylethylenediamine and the like. Further examples of peroxides include ammonium or potassium peroxodisulfate, hydrogen peroxide, benzoyl peroxide, lauroyl peroxide, octanoyl peroxide, succinic peroxide, t-butylperoxy 2-ethylhexanoate, and the like. be able to. Most preferred among these initiators is the water-soluble azo initiator 2,2′-azobis [2- (2-imidazolin-2-yl) propane] dihydrochloride, 2,2′-azobis [2- (2-Amidinopropane) dihydrochloride. The addition amount of the azo initiator is 50 to 500 ppm, preferably 70 to 200 ppm per monomer at the start of polymerization. However, since the polymerization rate is lowered by a single addition, it is preferable to add in several portions.

In addition, when copolymerizing with a redox initiator, it is difficult to control the polymerization when the polymerization is started at a temperature of 40 ° C. or more, and a rapid temperature rise or agglomeration of the polymerization solution occurs, resulting in a high degree of polymerization and stability. Since a dispersion liquid cannot be obtained, 15-35 degreeC is preferable. The initiator is added at a rate of 5 to 100 ppm, preferably 10 to 50 ppm per monomer at the start of polymerization. However, since the polymerization rate is lowered by a single addition, it is preferably added several times. As addition frequency, it is 2-5 times, Preferably it is 2-3 times. The addition amount of the polymer dispersant composed of these ionic polymers is 1 to 30% by mass, preferably 2 to 20% by mass with respect to the monomer. If it is 1% by mass or less, there is no effect as a dispersing agent, and if it is 30% by mass or more, the viscosity of the dispersion becomes high and the cost becomes disadvantageous.

The water-soluble polymer dispersion in the present invention is used for agglomeration treatment of municipal sewage, human waste, raw sludge from general industrial wastewater, surplus sludge, agglomerated sludge, digested sludge, or mixed sludges thereof, or a decanter, belt press, filter press. , Chemicals added when coagulating and dewatering with a screw press dehydrator, etc., oil separation process or oil separation process used in industrial wastewater containing oil, and oil separation agent used in processing, drainage improver used in papermaking process, yield improver, 0.5 mass% salt which can be used as a papermaking agent such as a valuable material recovery agent in white water and serves as an index of the molecular weight of the water-soluble polymer dispersion in the present invention in order to exert its function as these uses The aqueous solution viscosity, i.e., the aqueous solution viscosity in a 2 mass% ammonium sulfate aqueous solution at 0.5 mass% measured at 25C of the water-soluble polymer constituting the dispersion is 5 to 1 It is in the range of 0mPa · s, 20~150mPa · s is preferable. The aqueous solution viscosity in a 4% by mass sodium chloride aqueous solution is in the range of 5 to 150 mPa · s, and preferably 15 to 150 mPa · s.

The water-soluble polymer dispersion and the method for producing the same according to the present invention will be specifically described below, but the present invention is not limited to the following examples.

(Production Example 1) In a 0.5 L separable flask equipped with an anchor blade stirrer, a cooling tube and a nitrogen introduction tube, 154.2 g of demineralized water, 20.5 g of 35 mass% polydiallyldimethylammonium chloride, and sodium chloride 11 0.1 g and sodium sulfate 4.5 g were added, and the mixture was heated to 40 ° C. with stirring and dissolved uniformly. Next, 41.7 g of 50% by mass acrylamide, 10.9 g of 80% by mass acryloyloxyethyltrimethylammonium chloride, and 38 g of 80% by mass acryloyloxyethyldimethylbenzylammonium chloride were added to make a homogeneous solution, and immersed in a 40 ° C. hot water bath. The temperature was stabilized. Next, in a nitrogen atmosphere, 10 ppm by mass of 2,2′-azobis [2- (2-imidazolin-2-yl) propane] dihydrochloride aqueous solution as a polymerization initiator was added at 200 ppm per monomer and stirred. Polymerization was carried out at 40 ° C. for 18 hours. After completion of the reaction, 18 g of sodium sulfate was added to the obtained dispersion, and the mixture was stirred until the remaining sodium sulfate was not dissolved to obtain a water-soluble polymer dispersion. The molar composition ratio of this water-soluble polymer is acrylamide / acryloyloxyethyltrimethylammonium chloride / acryloyloxyethyldimethylbenzylammonium chloride = 65/10/25 mol%. The dispersion had a viscosity of 526 mPa · s, and the viscosity when the water-soluble polymer dispersion was dissolved in a 2% by mass aqueous ammonium sulfate solution at a concentration of 0.5% by mass was 85 mPa · s. This is shown in Table 1 as Example 1. The total nitrogen content of this water-soluble polymer dispersion is theoretically 23,87 ppm (vs. dispersion).

(Production Example 2) In a 0.5 L separable flask equipped with an anchor blade stirrer, a cooling pipe and a nitrogen introducing pipe, 139.2 g of demineralized water, 32.4 g of 35% by mass polydiallyldimethylammonium chloride, and further sodium chloride 6 .3 g and sodium sulfate 4.2 g were added, and the mixture was heated to 40 ° C. with stirring and dissolved uniformly. Next, 24.6 g of 50% by mass acrylamide, 20.9 g of 80% by mass acryloyloxyethyltrimethylammonium chloride, and 58.2 g of 80% by mass acryloyloxyethyldimethylbenzylammonium chloride were added to obtain a homogeneous solution, and a hot bath at 40 ° C. So as to stabilize the temperature. Next, in a nitrogen atmosphere, 10 ppm by mass of 2,2′-azobis [2- (2-imidazolin-2-yl) propane] dihydrochloride aqueous solution as a polymerization initiator was added at 200 ppm per monomer and stirred. Polymerization was carried out at 40 ° C. for 18 hours. After the completion of the reaction, 14 g of sodium sulfate was added to the obtained dispersion, and the mixture was stirred until there was no undissolved sodium sulfate to obtain a water-soluble polymer dispersion. The molar composition ratio of this water-soluble polymer is acrylamide / acryloyloxyethyltrimethylammonium chloride / acryloyloxyethyldimethylbenzylammonium chloride = 40/20/40 mol%. This dispersion was 5460 mPa · s, and the viscosity when the dispersion was dissolved in a 2% by mass ammonium sulfate aqueous solution to a concentration of 0.5% by mass was 71 mPa · s. This is shown in Table 1 as Example 2. The total nitrogen content of this water-soluble polymer dispersion is 23448 ppm (vs. dispersion) as a theoretical value.

(Production Example 3) In a 0.5 L separable flask equipped with an anchor blade stirrer, a cooling pipe and a nitrogen introduction pipe, 156 g of demineralized water, 25.7 g of 35% by mass polydiallyldimethylammonium chloride, and further 14.8 g of sodium chloride 4.8 g of sodium sulfate was added, and the mixture was heated to 40 ° C. with stirring and dissolved uniformly. Next, 63.3 g of 50% by mass acrylamide and 16.7 g of 80% by mass acryloyloxyethyldimethylbenzylammonium chloride were added to obtain a homogeneous solution, which was then immersed in a 40 ° C. hot water bath to stabilize the temperature. Next, in a nitrogen atmosphere, 10 ppm by mass of 2,2′-azobis [2- (2-imidazolin-2-yl) propane] dihydrochloride aqueous solution was added as a polymerization initiator at 100 ppm per monomer and stirred. Polymerization was carried out at 40 ° C. for 18 hours. After the completion of the reaction, 18.7 g of sodium sulfate was added to the obtained dispersion, and the mixture was stirred until the sodium sulfate remained undissolved to obtain a water-soluble polymer dispersion. The molar composition ratio of this water-soluble polymer is acrylamide / acryloyloxyethyldimethylbenzylammonium chloride = 90/10 mol%. This dispersion was 11600 mPa · s, and the viscosity when the dispersion was dissolved in a 4% by mass sodium chloride aqueous solution to a concentration of 0.5% by mass was 52 mPa · s. This is shown in Table 1 as Example 3. The total nitrogen content of this water-soluble polymer dispersion is 25715 ppm (vs. dispersion) as a theoretical value.

(Production Example 4) In a 0.5 L separable flask equipped with an anchor blade stirrer, a cooling pipe and a nitrogen introduction pipe, 193.6 g of demineralized water, 12.3 g of 35% by mass polydiallyldimethylammonium chloride, and 12% of sodium chloride 0.4 g and magnesium sulfate 4.9 g were added, and the mixture was heated to 36 ° C. with stirring and dissolved uniformly. Next, 25.0 g of 50% by mass acrylamide, 6.6 g of 80% by mass acryloyloxyethyltrimethylammonium chloride, and 22.8 g of 80% by mass acryloyloxyethyldimethylbenzylammonium chloride were added to form a homogeneous solution, and a 36 ° C. water bath So as to stabilize the temperature. Next, in a nitrogen atmosphere, 10 ppm by mass of 2,2′-azobis [2- (2-imidazolin-2-yl) propane] dihydrochloride aqueous solution as a polymerization initiator was added at 80 ppm per monomer and stirred. Polymerization was carried out at 36 ° C. for 18 hours. After the completion of the reaction, 17.0 g of magnesium sulfate was added to the obtained dispersion, and the mixture was stirred until the magnesium sulfate was not dissolved to obtain a water-soluble polymer dispersion. The molar composition ratio of this water-soluble polymer is acrylamide / acryloyloxyethyltrimethylammonium chloride / acryloyloxyethyldimethylbenzylammonium chloride = 65/10/25 mol%. This dispersion was 425 mPa · s, and the viscosity when the dispersion was dissolved in a 2% by mass ammonium sulfate aqueous solution to a concentration of 0.4% by mass was 61 mPa · s. This is shown in Table 1 as Example 4. The total nitrogen content of this water-soluble polymer dispersion is 15131 ppm (vs. dispersion) as a theoretical value.

  (Comparative Production Example 1) Production was carried out under the same conditions as in Example 1 using only sodium sulfate as the inorganic salt. To a 0.5 L separable flask equipped with an anchor blade stirrer, a cooling pipe and a nitrogen introduction pipe, 154.2 g of demineralized water, 20.5 g of 35% by mass polydiallyldimethylammonium chloride, and 15.5 g of sodium sulfate were added. The temperature was raised to 40 ° C. with stirring, and the mixture was uniformly dissolved. Next, 41.7 g of 50% by mass acrylamide, 10.9 g of 80% by mass acryloyloxyethyltrimethylammonium chloride, and 38 g of 80% by mass acryloyloxyethyldimethylbenzylammonium chloride were added to make a homogeneous solution, and immersed in a 40 ° C. hot water bath. The temperature was stabilized. Next, in a nitrogen atmosphere, 10 ppm by mass of 2,2′-azobis [2- (2-imidazolin-2-yl) propane] dihydrochloride aqueous solution as a polymerization initiator was added at 200 ppm per monomer and stirred. Polymerization was started at 40 ° C. During the reaction, the viscosity of the reaction solution increased, making stirring difficult and solidifying.

  (Comparative Production Example 2) Under the same conditions as in Example 1, the polymer dispersant polydiallyldimethylammonium chloride was produced in place of polyacryloyloxyethyltrimethylammonium chloride. In a 0.5 L separable flask equipped with an anchor blade stirrer, a condenser tube and a nitrogen inlet tube, 118 g of demineralized water, 56.7 g of 20% by mass polyacryloyloxyethyltrimethylammonium chloride, 11.1 g of sodium chloride, sodium sulfate 4.5g was added, and it heated up to 40 degreeC with stirring and melt | dissolved uniformly. Next, 41.7 g of 50% by mass acrylamide, 10.9 g of 80% by mass acryloyloxyethyltrimethylammonium chloride, and 38 g of 80% by mass acryloyloxyethyldimethylbenzylammonium chloride were added to make a homogeneous solution, and immersed in a 40 ° C. hot water bath. The temperature was stabilized. Next, in a nitrogen atmosphere, 10 ppm by mass of 2,2′-azobis [2- (2-imidazolin-2-yl) propane] dihydrochloride aqueous solution as a polymerization initiator was added at 200 ppm per monomer and stirred. Polymerization was started at 40 ° C. During the reaction, the viscosity of the reaction solution increased, making stirring difficult and solidifying.

(Table 1)
AAM: acrylamide DMQ: acryloyloxyethyltrimethylammonium chloride DMBZ: acryloyloxyethyldimethylbenzylammonium chloride polymer dispersant p-DD: polydiallyldimethylammonium chloride polymer dispersant p-DMQ: polyacryloyloxyethyltrimethylammonium Salt during chloride polymerization: (a) sodium chloride, (b) sodium sulfate, (c) magnesium sulfate monomer concentration: mass ratio of monomer to water-soluble polymer dispersion inorganic salt concentration: water-soluble polymer dispersion Mass ratio of inorganic salt to liquid Dispersion viscosity: Viscosity of water-soluble polymer dispersion measured at 25 ° C. 0.5% by weight Salt aqueous solution viscosity: (Examples 1, 2, 4) Polymer in 2% by weight ammonium sulfate water To 25 ° C when dissolved to a concentration of 0.5% by mass There viscosity was measured, viscosity measured at 25 ° C. when dissolved as polymer concentration of 0.5 wt% (Example 3) 4% by weight sodium chloride in water.

In Examples 1 to 4 of water-soluble polymer dispersions obtained using polydiallyldimethylammonium chloride as a polymer dispersant and chloride ions and polyvalent anions as inorganic salts, the total amount of inorganic salts is: It is a low water-soluble polymer dispersion having a content of 8.1 to 12.7% by mass and an inorganic salt content of less than 15% by mass. In Comparative Production Example 1 in which sodium chloride was not used as an inorganic salt, and in Comparative Production Example 2 in which a polymer dispersant containing no diallyldimethylammonium chloride was used as a structural unit, a dispersion could not be produced. Using a polymer dispersant containing diallyldimethylammonium chloride as a structural unit, and using a chloride ion and a polyvalent anion together as an inorganic salt, the dispersion can be suppressed without using ammonium sulfate. Was found to be obtained.

Claims (4)

In a salt aqueous solution containing a chloride ion and a polyvalent anion, a monomer or monomer mixture aqueous solution containing the monomer represented by the following general formula (1) as an essential component is constituted in the salt aqueous solution. A water-soluble polymer dispersion obtained by co-existing a polymer dispersant containing a polymer containing diallyldimethylammonium chloride as a unit, and dispersion polymerization under stirring, with respect to the total amount of the water-soluble polymer dispersion A water-soluble polymer dispersion, wherein the total amount of the inorganic salt is less than 15% by mass.
General formula (1)
R1 is hydrogen or a methyl group, R2 and R3 are alkyl groups having 1 to 3 carbon atoms, alkoxy groups, and R4 is an alkyl group or aryl group having 7 to 20 carbon atoms. A represents oxygen or NH, B represents an alkylene group or alkoxylene group having 2 to 4 carbon atoms, and X1 represents an anion. The water-soluble polymer dispersion according to claim 1, wherein the salt containing the polyvalent anion is sodium sulfate or magnesium sulfate. In a salt aqueous solution containing a chloride ion and a polyvalent anion, a monomer or monomer mixture aqueous solution containing the monomer represented by the following general formula (1) as an essential component is constituted in the salt aqueous solution. A water-soluble polymer dispersion obtained by co-existing a polymer dispersant containing a polymer containing diallyldimethylammonium chloride as a unit, and dispersion polymerization under stirring, with respect to the total amount of the water-soluble polymer dispersion A method for producing a water-soluble polymer dispersion, wherein the total amount of the inorganic salt is less than 15% by mass.
General formula (1)
R1 is hydrogen or a methyl group, R2 and R3 are alkyl groups having 1 to 3 carbon atoms, alkoxy groups, and R4 is an alkyl group or aryl group having 7 to 20 carbon atoms. A represents oxygen or NH, B represents an alkylene group or alkoxylene group having 2 to 4 carbon atoms, and X1 represents an anion. The method for producing a water-soluble polymer dispersion according to claim 3, wherein the salt containing the polyvalent anion is sodium sulfate or magnesium sulfate.