JPH093203A - Water-based dispersion of water-soluble polymer - Google Patents

Abstract

PURPOSE: To obtain a water-based dispersion of a water-soluble polymer containing the water-soluble polymer, a water-soluble inorganic salt, water- insoluble inorganic fine particles and water, keeping good fluidity with low viscosity, excellent in handleability, economic efficiency and safety and suitable for coagulating and dehydrating agent for sludge, an additive for paper, etc. CONSTITUTION: This dispersion contains (A) preferably 10-50wt.% water-soluble polymer such as polyacrylamide, (B) preferably 10-40wt.% water-soluble inorganic salt such as sodium nitrate, (C) preferably 0.5-20wt.% water-insoluble inorganic fine particles such as fine particles of silicon oxide, and (D) water.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an aqueous dispersion of a water-soluble polymer. More specifically, the present invention relates to a stable aqueous dispersion of a water-soluble polymer used as a coagulant dehydration agent for sludge, an additive for paper, etc., and uses an oil like a water-in-oil emulsion polymer. Without
The present invention relates to an aqueous dispersion of a water-soluble polymer which is liquid and does not generate dust during handling, and has excellent handling properties in terms of automation and labor saving.

[0002]

2. Description of the Related Art Conventionally, a large amount of water-soluble polymers such as cationic polymers have been used as a coagulating dehydration agent for sludge and an additive for paper. Such a water-soluble polymer is generally required to have a high molecular weight, and in particular, a polymer having a dissociative group introduced therein and being made into an electrolyte has a large polymer chain due to electrostatic repulsion between ionizing groups in water. Since it spreads, even a low-concentration aqueous solution tends to have high viscosity. When the viscosity of the aqueous solution becomes high, various difficulties arise in handling such as pumping being impossible. Therefore, even water-soluble polymers are often commercialized and handled in the form of powder. However, products in powder form also have safety problems such as generation of dust during handling, and need to be dissolved before use, which requires time and labor. For this reason, a liquid product in which a water-soluble polymer is easy to handle is required, and various proposals have been made. For example, by using a water-in-water emulsion as the water-soluble polymer, it is possible to improve handleability, automate the work, and save labor, but since mineral oil is used, odor and safety are reduced. Moreover, improvement is required from the viewpoint of global environment protection. Water-based liquid products have also been developed, but many of them are difficult to handle in terms of stability and workability, such as poor dispersibility and high solution viscosity. Further, a liquid product in which a polymer is hydrophobically modified with a benzyl group and has low viscosity and excellent dispersibility has been commercialized, but the benzyl group may pose a problem in terms of safety. Further, Japanese Unexamined Patent Application Publication No.
105809 proposes a method for producing an aqueous dispersion of a water-soluble polymer by polymerizing a benzylammonium-based cationic monomer in a polyvalent salt aqueous solution. However, it is difficult to increase the molecular weight of a polymer containing a benzylammonium-based cationic monomer, and the cation equivalent value cannot be increased. Therefore, the application range of coagulants, sludge dewatering agents, paper additives, etc. is narrowed. The present inventors have previously proposed a composition in which a cationic polymer having an amidine structure or an amine structure is dispersed in water containing an inorganic salt, a water-soluble polymer and a surfactant. This aqueous dispersion composition is an aqueous dispersion that does not use oil, has a low viscosity, is easy to handle, and has excellent workability, but the development of a highly concentrated dispersion of a water-soluble polymer that is still versatile Is desired.

[0003]

DISCLOSURE OF THE INVENTION The present invention provides a stable aqueous dispersion of a water-soluble polymer which maintains a low viscosity even at a high concentration and is easy to handle in terms of automation and labor saving. It was made for the purpose.

[0004]

Means for Solving the Problems As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that the stability can be improved by dispersing a water-soluble polymer in water containing an inorganic salt and inorganic fine particles. It has been found that an excellent and easy-to-handle aqueous dispersion can be obtained, and the present invention has been completed based on this finding. That is, the present invention includes (1) a water-soluble polymer, a water-soluble inorganic salt, a water-insoluble inorganic fine particle, and an aqueous dispersion of a water-soluble polymer, and (2) a water-insoluble polymer. Wherein the inorganic fine particles are fine particles of silicon oxide, the aqueous dispersion of the water-soluble polymer according to item (1),
Is provided. Further, as a preferred embodiment of the present invention, (3) the content of the water-soluble polymer is 10 to 50% by weight, the content of the water-soluble inorganic salt is 10 to 40% by weight, and the water-insoluble inorganic fine particles are Content of 0.5-2
0% by weight of an aqueous dispersion of the water-soluble polymer according to any of (1) to (2), (4) a water-soluble polymer according to any one of (1) to (3), wherein the water-soluble polymer is polyacrylamide. Aqueous dispersion, (5) The water-soluble polymer is a cationic polymer, Aqueous dispersion of the water-soluble polymer according to (1) to (3), (6) The cationic polymer is represented by the following general formula [1]. An aqueous dispersion of the water-soluble polymer according to item (5), which has an amidine unit represented or an amine unit represented by the following general formula [2]:

Embedded image (However, in the formula, R ¹ and R ² are hydrogen or a methyl group, and X ⁻ is a salt-forming ion.) (7) The water-soluble polymer is an anionic polymer.
An aqueous dispersion of the water-soluble polymer according to items (1) to (3),
(8) An aqueous dispersion of the water-soluble polymer according to the item (7), in which the anionic polymer has a carboxylic acid unit.

The water-soluble polymer used in the present invention can be used without particular limitation as long as it is a polymer which is soluble in water at room temperature. Such water-soluble polymers include, for example, starch, glucomannan, sodium alginate, gum arabic, guar gum, xanthan gum, lanzan gum, pullulan, dextran, gelatin, natural water-soluble polymers such as casein, methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose. In addition to semi-synthetic water-soluble polymers such as carboxymethyl starch and cationized starch, various synthetic water-soluble polymers can be used. Examples of the synthetic water-soluble polymer include a cationic polymer containing an amidine unit obtained by hydrolyzing a copolymer of N-vinylcarboxylic acid amide and acrylonitrile, N
-Vinylcarboxylic acid amide homopolymer or cationic polymer having vinylamine units obtained by hydrolyzing a copolymer containing N-vinylcarboxylic acid amide as an essential component, hydrochloric acid of N, N-dimethylaminoethyl (meth) acrylate Copolymerization of (meth) acrylamide with salts, nitrates, acetates, methyl chloride quaternary compounds, methyl bromide quaternary compounds, methyl iodide quaternary compounds, ethyl iodide quaternary compounds, benzyl chloride quaternary compounds, etc. The resulting cationic polymer, N, N-dimethylaminopropyl (meth) acrylamide hydrochloride, nitrate, acetate,
Cationic polymer obtained by copolymerization of (meth) acrylamide with methyl chloride quaternary compound, methyl bromide quaternary compound, methyl iodide quaternary compound, ethyl iodide quaternary compound, benzyl chloride quaternary compound, dimethyl Cationic polymer obtained by copolymerization of diallyl ammonium chloride and acrylamide, homopolymer of N, N-dimethylaminoethyl (meth) acrylate tertiary or quaternary ammonium salt, homopolymer of dimethyl diallyl ammonium chloride, polyethyleneimine, Poly (meth) acrylamide, poly (N-vinylpyrrolidone),
Polyethylene oxide, polypropylene oxide,
Nonionic polymers such as poly (N-substituted acrylamide), polyvinyl alcohol, polyvinyl ether, poly (meth) acrylic acid and its alkali metal salts, polyvinyl sulfonic acid, poly (2-acrylamido-2-methylpropane sulfonic acid), polystyrene Examples thereof include anionic polymers such as sulfonic acid.

Further, in the synthetic water-soluble polymer used in the present invention, another copolymerizable vinyl monomer can be copolymerized within a range in which the water solubility of the polymer is not lost. Examples of such copolymerizable vinyl monomers include (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, N-isopropyl (meth) acrylamide, styrene and methyl. (Meth) acrylate, vinyl acetate, acrylonitrile, nonionic monomers such as N-vinylpyrrolidone, (meth) acrylic acid, maleic acid, fumaric acid or alkali metal salts thereof, vinylsulfonic acid, 2-acrylamido-2-methylpropane Anionic monomers such as sulfonic acid, styrene sulfonic acid or their alkali metal salts, N, N-dimethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylamide tertiary salts or quaternary ammonium salts Such as cation And the like. In the aqueous dispersion of the water-soluble polymer of the present invention, one type of water-soluble polymer can be used alone, and two or more types of water-soluble polymers can be mixed as long as the water-solubility is not lost by mixing. Can be used. Content of water-soluble polymer is 10-5
It is preferably 0% by weight, more preferably 10 to 30% by weight. Water-soluble polymer content is 10
If it is less than wt%, the concentration of the water-soluble polymer in the aqueous dispersion will be low, and the amount of the aqueous dispersion required to obtain the required amount of the water-soluble polymer will increase. When the content of the water-soluble polymer is more than 50% by weight, the particles of the water-soluble polymer in the water-based dispersion are likely to aggregate, and the stability of the water-based dispersion may be reduced.

The water-soluble inorganic salt used in the present invention can be used without particular limitation as long as it is a water-soluble inorganic salt up to a desired concentration. Examples of such inorganic salts include nitrates such as sodium nitrate, potassium nitrate, magnesium nitrate, calcium nitrate, ammonium nitrate, sodium sulfate, potassium sulfate, magnesium sulfate, ammonium sulfate, sodium hydrogen sulfate, potassium hydrogen sulfate, ammonium hydrogen sulfate, and the like. Sulfate, potassium phosphate, dipotassium hydrogen phosphate, potassium dihydrogen phosphate, sodium phosphate, disodium hydrogen phosphate,
Examples thereof include phosphates such as sodium dihydrogen phosphate and ammonium phosphate, and halides such as sodium chloride, potassium chloride, sodium bromide, potassium bromide, sodium iodide, and potassium iodide. In the aqueous dispersion of the water-soluble polymer of the present invention, one type of water-soluble inorganic salt can be used alone, or two or more types of water-soluble inorganic salt can be mixed and used. When using an inorganic salt having a relatively low solubility in water, increase the content of the inorganic salt in water by using two or more kinds of inorganic salts having different cation components or anion components or both. You can The content of the water-soluble inorganic salt is preferably 10 to 40% by weight, and 20 to 40
More preferably, it is wt%. When the content of the water-soluble inorganic salt is less than 10% by weight, the particles of the water-soluble polymer in the aqueous dispersion may easily aggregate, and the stability of the aqueous dispersion may be reduced. In order to obtain a stable aqueous dispersion of a water-soluble polymer having a low viscosity, a water-soluble inorganic salt content of 40% by weight is sufficient, usually 40% by weight.
A water-soluble inorganic salt exceeding 1 is unnecessary.

The water-insoluble inorganic fine particles used in the present invention are not particularly limited, and examples thereof include talc, calcium carbonate,
Fine particles such as glass powder, silicon oxide, clay, kaolin, barium sulfate, wollastonite, mica, titanium oxide, carbon black, diatomaceous earth, magnesium hydroxide and various metal powders can be used. Among these water-insoluble inorganic fine particles, fine particles of silicon oxide can be particularly preferably used. In the aqueous dispersion of the water-soluble polymer of the present invention, one kind of water-insoluble inorganic fine particles can be used alone, and two or more kinds of water-insoluble inorganic fine particles can be mixed and used. . The content of the water-insoluble inorganic fine particles is preferably 0.5 to 20% by weight, more preferably 1 to 5% by weight. If the content of the water-insoluble inorganic fine particles is less than 0.5% by weight, the particles of the water-soluble polymer in the aqueous dispersion liquid tend to aggregate, and the stability of the aqueous dispersion liquid may decrease. In order to obtain a stable aqueous dispersion of a water-soluble polymer having a low viscosity, it is sufficient that the content of the water-insoluble inorganic fine particles is 20% by weight, and usually, the water-insoluble inorganic exceeding 20% by weight is used. No fine particles are needed. In the aqueous dispersion of the water-soluble polymer of the present invention, a surfactant can be added if necessary. The surfactant to be added is not particularly limited, and examples thereof include fatty acid soap, alkylbenzene sulfonate, alkane sulfonate, α-olefin sulfonate, N-acyl amino acid salt, N- (2-sulfo) ethyl-N. -Methyl alkane amide salt, dialkyl 2-sulfosuccinate salt, anionic surfactant such as alkyl naphthalene sulfonate, cationic surfactant such as alkyl trimethyl ammonium salt, alkyl pyridinium salt, polyoxyethylene alkyl ether, Nonionic surfactants such as phenyl polyoxyethylene alkyl ether, polyethylene glycol fatty acid ester, polyhydric alcohol fatty acid ester, N, N-di (alkanol) alkaneamide, amphoteric surfactant such as betaine and sulfobetaine. Door can be. To the aqueous dispersion of the water-soluble polymer of the present invention, one kind of surfactant may be added alone, and an anionic surfactant and a nonionic surfactant or a cationic surfactant and a nonionic surfactant may be added. The agents can be mixed and added. The addition amount of the surfactant is preferably 0 to 10% by weight. By adding a surfactant to the aqueous dispersion of the present invention, the dispersibility of the water-soluble polymer is improved.

The method for producing the aqueous dispersion of the water-soluble polymer of the present invention is not particularly limited, and the water-soluble polymer, the water-soluble inorganic salt, and the water-insoluble inorganic fine particles are mixed in water in any order to mix them. It can be manufactured. For example, it can be produced by preparing an aqueous solution of an inorganic salt, dispersing water-insoluble inorganic fine particles therein, and then adding a powdery water-soluble polymer and stirring. Further, it can be produced by adding a water-soluble inorganic salt to an aqueous solution of a water-soluble polymer to dissolve it, and then adding water-insoluble inorganic fine particles. Alternatively, it can be produced by mixing the water-soluble polymer, the water-soluble inorganic salt, and the water-insoluble inorganic fine particles in a dry state, and then simultaneously adding to water and stirring. Furthermore, in an aqueous solution of a water-soluble inorganic salt in which water-insoluble inorganic fine particles are dispersed,
It can be produced by polymerizing monomers that form a water-soluble polymer. In the aqueous dispersion of the water-soluble polymer of the present invention, the water-soluble polymer molecules contract and precipitate due to the salting-out effect in the presence of the inorganic salt to form an aqueous dispersion. When the aqueous dispersion of the water-soluble polymer of the present invention is diluted with water, the water-soluble polymer is dissolved in water again. Water-insoluble inorganic fine particles such as silicon oxide are adsorbed on the surface of the precipitated water-soluble polymer particles, preventing the water-soluble polymer particles from aggregating into giant particles and increasing the stability of the aqueous dispersion. . Similarly, the surfactant is also adsorbed on the surface of the precipitated water-soluble polymer particles,
It is considered to improve the stability of the aqueous dispersion.

[0010]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the present invention. In addition, in Examples and Comparative Examples, the intrinsic viscosity of the water-soluble polymer is a value measured at 30 ° C. using a 1N sodium chloride aqueous solution as a solvent. Example 1 23.5 g of water and 15 g of ammonium sulfate were put into a 100 ml beaker and uniformly dissolved, and further 1.5 g of silica [Shionogi Pharmaceutical Co., Ltd., Carplex 80] was added and dispersed. While stirring this mixed solution, the intrinsic viscosity is 20
10 g of dl / g polyacrylamide powder was added, and stirring was continued for 30 minutes. A fluid slurry was obtained, the viscosity of which was 750 cP. Example 2 Sodium nitrate 15 instead of 15 g of ammonium sulfate
The exact same procedure as in Example 1 was repeated except that g was used. A fluid slurry is obtained with a viscosity of 910 cP
Met. Comparative Example 1 40 g of water was placed in a 100 ml beaker and the same polyacrylamide powder 10 as that used in Example 1 was added with stirring.
g was added and stirring was continued for 30 minutes. A transparent gel-like substance was obtained and its viscosity was 200,000 cP. Comparative Example 2 25 g water and 15 ammonium sulfate in a 100 ml beaker
1 g of the same polyacrylamide powder as that used in Example 1 while stirring the solution and stirring the solution.
0 g was added and stirring was continued for 30 minutes. The polymer particles were aggregated and precipitated in the liquid. When the viscosity of this liquid was measured, it was 250 cP. Comparative Example 3 15 g of ammonium sulfate was used instead of 15 g of sodium sulfate.
The exact same operation as in Comparative Example 2 was repeated except that g was used. The polymer particles were aggregated and precipitated in the liquid. When the viscosity of this liquid was measured, it was 250 cP. Comparative Example 4 38 g of water and 2 g of the same silica as used in Example 1 were placed in a 100 ml beaker and dispersed, and 10 g of the same polyacrylamide powder as used in Example 1 was added while stirring this solution. The stirring was continued for 30 minutes.
A cloudy gel-like substance was obtained with a viscosity of 24,000.
It was cP. Example 3 Instead of 10 g of polyacrylamide, an intrinsic viscosity of 21
dl / g N, N-dimethylaminoethyl acrylate methyl chloride quaternary to acrylamide molar ratio 35/6
The exact same procedure as in Example 1 was repeated except that 10 g of the copolymer of 5 was used. A fluid slurry was obtained, the viscosity of which was 620 cP. Example 4 15 g of ammonium sulfate instead of 15 g of sodium nitrate
The exact same procedure as in Example 3 was repeated except that g was used. A fluid slurry is obtained with a viscosity of 720 cP
Met. Comparative Example 5 Exactly the same as Comparative Example 1 except that 10 g of the same methyl N, N-dimethylaminoethyl acrylate quaternary chloride and acrylamide copolymer as used in Example 3 were used instead of 10 g of polyacrylamide. The operation was repeated. A transparent gel-like substance is obtained, whose viscosity is 240,
000 cP. Comparative Example 6 The same operation as in Comparative Example 2 was carried out except that 10 g of the same quaternized N, N-dimethylaminoethyl acrylate and acrylamide copolymer as used in Example 3 were used instead of 10 g of polyacrylamide. I repeated. The polymer particles were aggregated and precipitated in the liquid. When the viscosity of this liquid was measured, it was 220 cP. Comparative Example 7 The same operation as in Comparative Example 3 was performed except that 10 g of the same quaternized N, N-dimethylaminoethyl acrylate and acrylamide copolymer as used in Example 3 were used instead of 10 g of polyacrylamide. I repeated. The polymer particles were aggregated and precipitated in the liquid. When the viscosity of this liquid was measured, it was 270 cP. Comparative Example 8 Exactly the same as Comparative Example 4 except that 10 g of the same methyl chloride quaternary N, N-dimethylaminoethyl acrylate and acrylamide copolymer as used in Example 3 were used instead of 10 g of polyacrylamide. The operation was repeated. A cloudy gel-like substance was obtained, whose viscosity was 25
It was 2,000 cP. Example 5 Instead of 10 g of polyacrylamide, an intrinsic viscosity of 20 was obtained.
The exact same procedure as in Example 1 was repeated except that 10 g of a copolymer of sodium acrylate of dl / g and acrylamide in a molar ratio of 32/68 was used. A fluid slurry was obtained, the viscosity of which was 1,000 cP. Example 6 Sodium nitrate 15 instead of 15 g ammonium sulfate
Except for using g, the same operation as in Example 5 was repeated. A fluid slurry is obtained with a viscosity of 1,300
It was cP. Comparative Example 9 The exact same procedure as in Comparative Example 1 was repeated except that 10 g of the same sodium acrylate and acrylamide copolymer as used in Example 5 was used instead of 10 g of polyacrylamide. A transparent gel-like substance was obtained and its viscosity was 270,000 cP. Comparative Example 10 The same operation as in Comparative Example 2 was repeated, except that 10 g of the same sodium acrylate and acrylamide copolymer as used in Example 5 was used instead of 10 g of polyacrylamide. Polymer particles aggregate in the liquid,
Precipitated. When the viscosity of this liquid was measured, it was 210 cP
Met. Comparative Example 11 The same procedure as in Comparative Example 3 was repeated, except that 10 g of the same sodium acrylate and acrylamide copolymer as used in Example 5 was used instead of 10 g of polyacrylamide. Polymer particles aggregate in the liquid,
Precipitated. When the viscosity of this liquid was measured, it was 240 cP
Met. Comparative Example 12 The same operation as in Comparative Example 4 was repeated, except that 10 g of the same sodium acrylate and acrylamide copolymer as used in Example 5 was used instead of 10 g of polyacrylamide. A cloudy gel-like substance was obtained, and its viscosity was 290,000 cP. The results of Examples 1 to 6 and Comparative Examples 1 to 12 are summarized in Table 1.

[0011]

[Table 1]

[0012]

[Table 2]

[0013]

[Table 3]

As can be seen from the results shown in Table 1, the aqueous dispersions of the water-soluble polymers of the present invention in Examples 1-6 were
All of them are low-viscosity slurries that maintain a good fluid state, whereas Comparative Examples 1 and 4 containing no water-soluble inorganic salt,
The compositions of Nos. 5, 8, 9 and 12 all became extremely viscous gels, and Comparative Example 2 containing no silica,
In Nos. 3, 6, 7, 10 and 11, particles of the water-soluble polymer aggregated and precipitated, and a stable aqueous dispersion could not be obtained.

[0015]

The aqueous dispersion of the water-soluble polymer of the present invention has a low viscosity and maintains good fluidity, and when diluted with water, it becomes a uniform polymer aqueous solution again. The aqueous dispersion of the present invention in which the water-soluble polymer is a cationic polymer is excellent in handleability, economy and safety, and can be suitably used as a flocculating dehydrating agent for sludge and an additive for paper.

Claims (2)

[Claims] 1. An aqueous dispersion of a water-soluble polymer comprising a water-soluble polymer, a water-soluble inorganic salt, water-insoluble inorganic fine particles and water. 2. An aqueous dispersion of a water-soluble polymer according to claim 1, wherein the water-insoluble inorganic fine particles are fine particles of silicon oxide.