JP2002265739A - Stabilization method for acrylamide polymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for inhibiting the solidification of an acrylamide polymer dispersion over a long time during the storage of the dispersion. SOLUTION: In this stabilization method, 0.01-15 pts.wt. α,β-unsaturated carboxylic acid polymer is added to 100 pts.wt. acrylamide polymer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for stabilizing an acrylamide polymer. More specifically, the present invention relates to a method for stabilizing a dispersion in which an acrylamide polymer is dispersed in an aqueous medium containing a high concentration of an inorganic salt.

[0002]

2. Description of the Related Art Acrylamide polymers are polymer coagulants, thickeners, paper strength agents, retention agents, drainage improvers, oil recovery agents, civil engineering lubricants, civil engineering adhesives and soil adhesion preventives. And many other fields. Various methods have been proposed as methods for producing acrylamide polymers, but industrially they are mainly produced by aqueous solution polymerization.

[0003] In such an aqueous solution polymerization method, as the polymer concentration increases, the polymer becomes a gel containing water, and it is difficult to handle the polymer as it is when it is dissolved. Therefore, it is used as a low-concentration solution that is diluted and fluid, or dried and powdered. A method for producing an acrylamide polymer by water-in-oil emulsion polymerization or suspension polymerization in a hydrophobic solvent is also known (JP-A-5-194613).

[0004] However, some problems have been pointed out in the method for industrially producing such an acrylamide-based polymer. For example, in the case of aqueous solution polymerization, when acrylamide-based polymer is powdered from aqueous solution of acrylamide-based polymer, enormous heat energy is required for drying, and thermal three-dimensional cross-linking is caused by heating to make the polymer insoluble. Etc. occur. In addition, in water-in-oil emulsion polymerization or suspension polymerization in a hydrophobic solvent, there is a problem that equipment needs to be used for the use of a flammable solvent.

As a method of solving the above problems, the present inventors have proposed a method of dispersing an acrylamide polymer in an aqueous solution of an inorganic salt by precipitation polymerization of an acrylamide monomer in the presence of a vinylpyrrolidone polymer or the like. Application for liquid production method (JP-A-10-195116, JP-A-10-195116)
1-310615). According to this method, it is possible to obtain an aqueous dispersion in which fine particles of an acrylamide polymer are dispersed at a high concentration, and the polymer is easily swollen and dissolved by diluting the obtained dispersion with water, thereby dissolving the acrylamide. Since a uniform aqueous solution of the polymer is obtained, workability is extremely improved.

In addition, since a flammable organic solvent is not used, it can be manufactured safely and inexpensively, and has many features such as being economically excellent. However, it is difficult to stably store the obtained dispersion for a long time,
Applications may be limited in terms of practicality.

In general, when an aqueous solution of an acrylamide polymer is left for a long period of time, the degree of polymerization decreases due to the oxidative decomposition of the acrylamide polymer, and the viscosity of the aqueous solution decreases.
There is a problem in terms of stability such that insoluble swelling gel is generated due to intramolecular or intermolecular cross-linking caused by generation of an imide bond accompanied by deammonification in the amide side chain and performance is deteriorated.
In particular, the acrylamide-based polymer dispersion obtained by the precipitation polymerization method in a salt aqueous solution containing a high concentration of the inorganic salt is more unstable in terms of storage stability compared to the acrylamide-based polymer aqueous solution There is a tendency.

As a stabilizer for preventing the decomposition and deterioration of the acrylamide polymer, diphenylguanidines and / or salts thereof (Japanese Patent Publication No. 5-39978) and urea compounds such as guanylurea (Japanese Patent Publication No. 60-23
No. 683) is known. These have a certain effect on an aqueous solution of an acrylamide polymer, but have no stabilizing effect on a dispersion of an acrylamide polymer in an aqueous medium containing a high concentration of inorganic salt. .

The present inventors have proposed aminoguanidines and aqueous acrylamide polymers as a method for stabilizing a dispersion of an acrylamide polymer in an aqueous medium containing a high concentration of an inorganic salt as well as an aqueous solution of the acrylamide polymer. And / or a method of adding a reducing agent (Japanese Patent Application Laid-Open No. H11-209551).
JP-A-11-349773).

However, such a method can prevent the decomposition and deterioration of the acrylamide polymer, but suppresses the increase in the viscosity of the dispersion during storage and the solidification of the dispersion. May not be possible.

The present inventors filed a method of adding polyethylene glycol and / or polypropylene glycol as a method for suppressing the increase in viscosity of an acrylamide-based polymer dispersion during storage and the accompanying solidification of the dispersion. (Japanese Patent Application No. 2000-350125).

However, when the acrylamide-based polymer dispersion is used, it may be stored for a very long time in a storage tank or the like, and further stabilization of the acrylamide-based polymer dispersion has been demanded.

[0013]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for suppressing the solidification phenomenon of a liquid, which occurs during storage of an acrylamide polymer dispersion, for a long time.

[0014]

Means for Solving the Problems The inventors of the present invention have made intensive studies to solve the above-mentioned problems, and as a result, they have found that by adding a specific amount of an α, β-unsaturated carboxylic acid polymer to an acrylamide-based polymer. The present inventors have found that the solidification phenomenon of the dispersion can be suppressed for a long period of time, and completed the present invention.
That is, the present invention relates to an α, β-unsaturated carboxylic acid polymer 0.0
The present invention relates to a method for stabilizing an acrylamide polymer, which comprises adding 1 to 15 parts by weight.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The acrylamide polymer used in the present invention includes a homopolymer of acrylamide, a copolymer with another monomer copolymerizable with acrylamide, and a partially modified acrylamide homopolymer. , And mixtures thereof.

Examples of the other copolymerizable monomers include, for example, nonionic monomers such as methacrylamide and vinylpyridine, and (meth) acrylic acid (including two kinds of compounds of acrylic acid and methacrylic acid. (The same applies to the following.), 2- (meth) acrylamido-2-methylpropanesulfonic acid, fumaric acid, crotonic acid, maleic acid, styrenesulfonic acid or an alkali metal salt thereof, Anionic monomers such as alkaline earth metal salts and ammonium salts; and cationic monomers such as ethyl (meth) acrylate trimethylammonium chloride and propyl (meth) acrylate trimethylammonium chloride. Among them, alkali metal (meth) acrylate and alkaline earth metal (meth) acrylate are preferable from the viewpoint of industrial availability and low cost. These may be used alone or in combination of two or more.

The alkali metal (meth) acrylate,
Examples of the alkaline earth metal (meth) acrylate include lithium (meth) acrylate, sodium (meth) acrylate, potassium (meth) acrylate, magnesium (meth) acrylate, and calcium (meth) acrylate. Is mentioned. Of these, sodium acrylate is most preferably used from the viewpoint of industrial availability and low cost.

The content of the component derived from the other copolymerizable monomer in the copolymer is the same as the content of the component derived from the acrylamide and the component derived from the other copolymerizable monomer. Is preferably 40 mol% or less based on the total amount of 4
Exceeding 0 mol% is not preferred because the resulting polymer dissolves in the aqueous solution of the inorganic salt.

Examples of the partially modified acrylamide homopolymer include those obtained by converting 40 mol% or less of the amide groups contained in the acrylamide homopolymer to other functional groups by a chemical reaction. Specific examples thereof include, for example, a hydrolyzate with an alkali, a sulfomethylation reaction product with formaldehyde and sodium bisulfite, a Hoffman reaction product with sodium hypochlorite and an alkali,
And a Mannich reaction product of formaldehyde and an amine.

The method for stabilizing an acrylamide polymer according to the present invention is characterized in that the acrylamide polymer is a homopolymer of a high concentration of an inorganic salt and vinylpyrrolidone and / or a copolymer of vinylpyrrolidone and another monomer. Is particularly effective when present as a dispersion dispersed in an aqueous medium containing
The inorganic salt is not particularly limited, and examples thereof include ammonium salts of inorganic acids such as ammonium sulfate, ammonium nitrate, and diammonium hydrogen phosphate; potassium sulfate, sodium sulfate, magnesium sulfate, potassium nitrate, sodium nitrate, potassium chloride, and sodium chloride. Alkali metal salts and alkaline earth metal salts of inorganic acids such as calcium chloride, dipotassium hydrogen phosphate and monosodium hydrogen phosphate.

These are used singly or in a suitable mixture. Of these, ammonium salts of inorganic acids and sodium salts of inorganic acids are preferable, and ammonium sulfate and sodium sulfate are more preferable.

In the present invention, the concentration of the high-concentration inorganic salt is:
The concentration is preferably 5% by weight or more and a saturation concentration or less. For example, the concentration range is preferably 5 to 43% by weight for ammonium sulfate and 5 to 20% by weight for sodium sulfate.

The type of the copolymer of vinylpyrrolidone and another monomer is not particularly limited. For example, a copolymer of vinylpyrrolidone and vinyl acetate, a copolymer of vinylpyrrolidone and vinyl alcohol, a copolymer of vinylpyrrolidone and dimethylaminoethyl (meth) acrylate, or a quaternized product thereof can be used.

The amount of these homopolymers or copolymers used depends on the type, molecular weight and other conditions.
0.1 to 100 parts by weight of the acrylamide polymer
A range of 100 parts by weight is preferred. Moreover, the weight average molecular weight is usually 2,000,000 or less.

The α, β-unsaturated carboxylic acid polymer used in the present invention is not particularly restricted but includes polyacrylic acid, polymethacrylic acid, polyitaconic acid, polycrotonic acid and the like. Among them, polyacrylic acid and polymethacrylic acid are preferably used from the viewpoint that the effect of stabilizing the dispersion of the present invention can be seen over a longer period.

The weight average molecular weight of the α, β-unsaturated carboxylic acid polymer is not particularly limited.
000, preferably 2,000-80,000. If the weight average molecular weight is less than 500, the effect of stabilizing the dispersion may not be obtained. On the other hand, when the weight average molecular weight exceeds 100,000, it is difficult to uniformly dissolve in the acrylamide-based polymer dispersion, and the stabilizing effect may not be obtained.

The amount of the α, β-unsaturated carboxylic acid polymer to be added is based on 100 parts by weight of the acrylamide polymer.
It is 0.01 to 15 parts by weight, preferably 0.1 to 5 parts by weight. The amount of the α, β-unsaturated carboxylic acid polymer added is 0.
If the amount is less than 01 parts by weight, the effect of stabilizing the dispersion cannot be obtained. On the other hand, if the amount of the α, β-unsaturated carboxylic acid polymer exceeds 15 parts by weight, no effect commensurate with the added amount is obtained, which is not economical.

The acrylamide-based polymer dispersion liquid contains:
The method for adding the α, β-unsaturated carboxylic acid polymer is not particularly limited, but various addition methods are possible. For example, a method of directly adding an α, β-unsaturated carboxylic acid polymer to an acrylamide-based polymer dispersion, or a method of dissolving in an appropriate solvent such as water in advance and adding the same. Although it is effective to add the acrylamide-based polymer dispersion liquid during its production, it is effective to add the acrylamide-based polymer dispersion liquid after the polymerization reaction is almost completed in order to avoid adverse effects on the polymerization reaction and to obtain a polymer having a high molecular weight. Is preferred.

In the present invention, by adding a specific amount of the α, β-unsaturated carboxylic acid polymer to the acrylamide polymer, the solidification phenomenon of the dispersion can be suppressed for a long time. The effect of adding the α, β-unsaturated carboxylic acid polymer to suppress the solidification phenomenon of the dispersion over a long period of time has not been sufficiently elucidated, but the effect of the dispersed acrylamide-based polymer has been elucidated. It is considered that by acting as a protective colloid for the fine particles, the viscosity of the dispersion is reduced and the fluidity is improved, so that the solidification of the dispersion can be suppressed for a long period of time.

[0030]

EXAMPLES 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.

Example 1 45.1 g of acrylamide and 14.9 g of sodium acrylate were placed in a 500 mL reaction vessel equipped with a stirrer, a nitrogen inlet tube, a thermometer, and a reflux condenser.
g, polyvinylpyrrolidone (molecular weight 10,000) 4.
0 g, propylene glycol monomethyl ether 0.5
g, pure water (191.5 mL) was added to dissolve them, and then ammonium sulfate (140.0 g) and sodium sulfate (4.0 g) were further added. Oxygen in the solution is removed by aeration with nitrogen, potassium persulfate (20 mg) is added thereto, and the mixture is polymerized at 25 ° C. for 8 hours with stirring to obtain a dispersion containing 60 g of an acrylamide polymer having an anionization ratio of 20 mol%. I got The resulting dispersion has a viscosity of 4 at 25 ° C.
The viscosity average molecular weight of the obtained polymer was about 6.5 million.

To the obtained dispersion, 1.8 g of polyacrylic acid (molecular weight: 5,000) was added, and after sufficiently stirring, it was stored at 25 ° C. for one month, three months, and six months. The state of the dispersion at that time was visually observed. The results are shown in Table 1.

(Example 2) The procedure of Example 1 was repeated, except that the amount of polyacrylic acid was changed to 0.6 g. The results are shown in Table 1.

Example 3 Example 1 was repeated except that the amount of polyacrylic acid was changed to 0.12 g.
The same was done. The results are shown in Table 1.

Example 4 43.7 g of acrylamide and 16.3% of sodium acrylate were placed in a 500 mL reaction vessel equipped with a stirrer, a nitrogen inlet tube, a thermometer, and a reflux condenser.
g, 12.0 g of vinylpyrrolidone / vinyl acetate copolymer (70 mol% / 30 mol%, molecular weight 10,000) and 1.0 g of propylene glycol monomethyl ether were added, and 180 mL of pure water was added to dissolve them. rear,
Further, 130.0 g of ammonium sulfate and 17.0 g of sodium sulfate were added. Oxygen in the solution is removed by aeration with nitrogen, potassium persulfate (20 mg) is added thereto, and the mixture is polymerized at 25 ° C. for 8 hours with stirring to obtain a dispersion containing 60 g of an acrylamide polymer having an anionization ratio of 22 mol%. I got The viscosity of the obtained dispersion is 8200 m at 25 ° C.
Pa · s, and the viscosity average molecular weight of the obtained polymer was about 9.5 million.

To the obtained dispersion, 1.8 g of polymethacrylic acid (molecular weight 10,000) was added, and after sufficiently stirring, the dispersion was stored at 25 ° C. for one month, three months, and six months. The state of the dispersion was visually observed. The results are shown in Table 1.

Example 5 Example 4 was repeated except that the amount of polymethacrylic acid was changed to 0.6 g.
The same was done. The results are shown in Table 1.

Example 6 The procedure of Example 4 was repeated, except that the amount of polymethacrylic acid was changed to 0.12 g. The results are shown in Table 1.

Comparative Example 1 The procedure of Example 1 was repeated, except that polyacrylic acid was not added. The results are shown in Table 1.

[0040]

[Table 1]

Table 1 shows that the dispersions of the acrylamide-based polymers of Examples 1 to 6 have suppressed the solidification phenomenon for a long period of time.

[0042]

According to the present invention, the solidification phenomenon of the dispersion can be suppressed for a long time by adding a specific amount of the α, β-unsaturated carboxylic acid polymer to the acrylamide polymer. .

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08L 33:02 C08L 33:02 39:06) 39:06) (72) Inventor Shigeo Hamamoto Himeji, Hyogo Prefecture No. 1, Irifune-cho, Shikuma-ku Sumitomo Seika Co., Ltd. Functional resin research institute (72) Inventor Takao Okada 2081, Shinjoya, Kakogawa-shi, Hyogo Prefecture 5 (Reference) 4J002 BG012 BG131 BJ003 DD056 DD066 DF036 DG046 DH046 GD04 GJ01 GK04 GL00

Claims (10)

[Claims] An α, β-unsaturated carboxylic acid polymer is used in an amount of 0.01 to 1 based on 100 parts by weight of an acrylamide polymer.
A method for stabilizing an acrylamide polymer, comprising adding 5 parts by weight. 2. A state in which an acrylamide polymer is dispersed in an aqueous medium containing a high concentration of an inorganic salt and a homopolymer of vinylpyrrolidone and / or a copolymer of vinylpyrrolidone and another monomer. The method for stabilizing an acrylamide polymer according to claim 1, which is present. 3. The method for stabilizing an acrylamide polymer according to claim 2, wherein the high concentration of the inorganic salt in the aqueous medium is 5% by weight or more and a saturation concentration or less. 4. The method for stabilizing an acrylamide polymer according to claim 2, wherein the inorganic salt is an ammonium salt of an inorganic acid and / or a sodium salt of an inorganic acid. 5. The method for stabilizing an acrylamide polymer according to claim 4, wherein the ammonium salt of the inorganic acid is ammonium sulfate. 6. The method for stabilizing an acrylamide polymer according to claim 4, wherein the sodium salt of the inorganic acid is sodium sulfate. 7. The method according to claim 1, wherein the α, β-unsaturated carboxylic acid polymer is polyacrylic acid or polymethacrylic acid.
7. The method for stabilizing an acrylamide-based polymer according to any one of 6. 8. The acrylamide polymer is selected from the group consisting of a homopolymer of acrylamide, a copolymer with another monomer copolymerizable with acrylamide, and a partially modified acrylamide homopolymer. At least one
The method for stabilizing an acrylamide polymer according to any one of claims 1 to 7, which is a seed. 9. The content of a component derived from another copolymerizable monomer during the copolymerization of acrylamide with another monomer copolymerizable with acrylamide is the same as that of a component derived from acrylamide. The method for stabilizing an acrylamide-based polymer according to claim 8, wherein the amount is 40 mol% or less based on the total amount of the constituent components derived from other polymerizable monomers. 10. The method for stabilizing an acrylamide polymer according to claim 8, wherein the other copolymerizable monomer is sodium acrylate.