JPH0672170B2 - Method for producing water-soluble polymer dispersion - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention is widely used as a flocculant for treating wastewater, a dehydrating agent, a papermaking agent used in the papermaking process, a dispersion stabilizer for various suspension solutions, a soil conditioner, and the like. The present invention relates to a novel method for producing a water-soluble polymer.

(Prior Art) Conventionally, as a method for producing a water-soluble polymer used as described above, static polymerization in an aqueous solution, water-in-oil emulsion polymerization (JP-A-54-102388), hydrophobic solvent Suspension polymerization (Japanese Patent Application Laid-Open No. 54-69196).

Further, Japanese Patent Application Laid-Open No. 50-70489 is disclosed as precipitation polymerization in an aqueous salt solution, and Japanese Patent Publication No. 46-14907 is disclosed as polymerization in an aqueous salt solution containing acrylic acid as a main component at low pH.

(Object of the invention and problems to be solved) In the static polymerization method of an aqueous solution, in order to obtain a high molecular weight polymer, the polymerization is carried out at a monomer concentration of 10% by weight or more. Since it becomes a gelled form and it is difficult to dissolve it as it is, it is necessary to further dilute it and market it in a fluid low-concentration solution, or dry and powder it. When it is marketed at a low concentration, it has the disadvantage of high transportation costs, and when powdered, it requires a large amount of heat energy for drying, and heating causes three-dimensional cross-linking, resulting in water-insoluble parts. Has the drawback of causing

The water-in-oil type emulsion has flammability and has the drawback of wasting valuable organic solvent.
Since suspension polymerization in a hydrophobic solvent uses flammable substances such as cyclohexane and toluene, it has a drawback that a large amount of cost is required for manufacturing equipment.

Precipitation polymerization in an aqueous salt solution is low in cost in terms of equipment, is a good method, or has a drawback that the produced polymers adhere to each other to form a large lump, which makes handling very difficult. Further, the method disclosed in Japanese Examined Patent Publication No. 46-14907 is possible only with unneutralized acrylic acid, but it has not been successful for neutralized ones such as sodium salt of acrylic acid.

The present invention is directed to overcoming the above drawbacks.

(Means for Solving Problems) The present inventors have diligently aimed at overcoming these drawbacks and producing a dispersion liquid of a water-soluble polymer having good fluidity and easy handling in a low-cost production facility. As a result of research, the present invention has been reached. The present inventors have previously filed an application regarding the polymerization of a cationic monomer having a benzyl group bonded to an amino group in an aqueous salt solution (Japanese Patent Application No. 59-244152). It has been found that the same polymerization method can be applied to a water-soluble monomer mainly composed of a body, and the present invention has been completed.

That is, according to the present invention, when polymerizing a water-soluble monomer (A) mainly composed of an acrylamide-based monomer while precipitating a polymer in an aqueous salt solution with stirring, a high solubility that can be dissolved in the aqueous salt solution is obtained. The present invention relates to a method for producing a free-flowing water-soluble polymer dispersion, which comprises allowing a molecular electrolyte (B) to coexist.

The water-soluble monomer (A) mainly composed of acrylamide-based monomer includes one or two kinds of acrylamide-based monomer and other water-soluble monomer copolymerizable with the acrylamide-based monomer. A mixture with the above is included.

Examples of the acrylamide monomer include acrylamide, methacrylamide, N, N-dimethylacrylamide and the like. In addition, as the water-soluble copolymerizable monomer, (meth) acrylic acid alkali metal salt, 2-acrylamido-2-methylpropanesulfonic acid alkali metal salt, a cationic monomer represented by the following formula (II) And so on.

Since the present invention relates to a method for producing a water-soluble polymer,
As long as the polymer of the water-soluble monomer (A) mainly composed of acrylamide-based monomer is water-soluble, it is not limited to the combination of the above-mentioned monomers. For example, a monomer having a certain degree of solubility in water such as acrylonitrile can be used within a range in which the copolymer with the acrylamide monomer is water-soluble.

If the monomer that can be copolymerized with the acrylamide monomer has an ionic group, it may dissolve in an aqueous salt solution.
It is preferably not more than mol%.

Regarding the salt aqueous solution used as the dispersion medium for the polymerization used in the present invention, the condition is that the polymerization product is not dissolved. As its typical salt, sodium sulfate, ammonium sulfate,
Examples thereof include magnesium sulfate, aluminum sulfate, sodium chloride, sodium dihydrogen phosphate, diammonium monohydrogen phosphate, dipotassium monohydrogen phosphate, or a mixture of two or more of these salts. In salts other than these, as long as they do not dissolve the polymerization product,
It is the scope of the present invention.

The concentration of the salt aqueous solution varies depending on the molar ratio of the ionic monomer and the salt used and is not particularly limited, but is 15% by weight or more,
Ranges up to the solubility limit are generally preferred. After the polymerization, it is possible to further add a salt to the dispersion within the range of solubility to reduce the viscosity of the dispersion.

The polymer electrolyte (B) coexisted during the polymerization is not particularly limited as long as it dissolves in a salt aqueous solution that does not dissolve the formed polymer of the water-soluble monomer (A).

When the produced polymer is nonionic like polyacrylamide, both a cationic polyelectrolyte and an anionic polyelectrolyte can be used, but when the produced polymer is anionic, an anionic polyelectrolyte and a cationic polyelectrolyte are used. In this case, a cationic polyelectrolyte is preferable.

As the anionic polymer electrolyte, a monomer unit composed of an alkali metal acrylate and / or an alkali metal salt of 2-acrylamido-2-methylpropanesulfonic acid is used.
A polymer containing 30 to 100 mol% is preferable, and the cationic polyelectrolyte contains 20 to 100 of one or more cationic monomer units represented by the following formula (I).
Polymers containing mol% are preferred.

Typical examples of the cationic monomer of formula (I) include dimethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylamide, dimethylaminohydroxypropyl (meth) acrylate, and methyl chloride and dimethyl chloride. Examples thereof include those quaternized with sulfuric acid, and all monomers satisfying the formula (I) can be used.

The amount of the polymer electrolyte (B) is preferably 0.1% by weight or more based on the aqueous salt solution, and if it is less than 0.1%, the polymer produced cannot be obtained in a dispersed state, and large lumps attached to each other are not preferable.

Next, the polymerization method will be described in detail in Examples, but the outline thereof is as follows.

After a predetermined water-soluble monomer (A) was charged into a salt aqueous solution in which the polymer electrolyte (B) was dissolved and deoxygenated with nitrogen gas,
The polymerization is started under stirring with the addition of the polymerization initiator. When the polymerization is completed, polymer particles having a particle size of about 1 mm or less are obtained in a dispersed state. The monomer concentration at this time may be any amount of 5 parts by weight or more with respect to 100 parts by weight of the salt aqueous solution, and if it is less than 5 parts by weight, there is no superiority to aqueous solution polymerization. Also, the upper limit is possible until the fluidity of the product disappears.

The polymerization temperature varies depending on the type of the polymerization initiator and may be any temperature at which the initiator functions, and is not particularly limited. Also,
As the polymerization initiator, any commonly used redox type or azo type initiator may be used without limitation.

(Operation) The feature of the present invention resides in that the water-soluble monomer is polymerized in an aqueous salt solution in the presence of a polyelectrolyte capable of dissolving the aqueous solution while stirring.

At this time, the salt aqueous solution does not dissolve the produced polymer, and the action of the coexisting polyelectrolyte has not been sufficiently clarified, but it probably acts as a protective colloid and causes the electric repulsion of the polyelectrolyte. It is considered that this prevents the produced polymer from adhering and contributes to the stabilization of the dispersion.

(Examples) Next, the present invention will be described in more detail based on examples, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded.

Example 1 1 equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen inlet tube
In a 5-necked separable flask, a homopolymer of sodium acrylate (0.5% pure solution in water at a viscosity of 10c
p) 7.5 g, ammonium sulfate 42.5 g, diammonium hydrogen phosphate 42.5 g, and ion-exchanged water 331.8 g were added and dissolved, and then acrylamide 75 g and isopropyl alcohol 0.75 g as a chain transfer agent were charged, and the mixture was heated to 40 ° C. It was heated and replaced with nitrogen.

To this, 0.75 g of a 1% aqueous solution of ammonium persulfate was added as a polymerization initiator and 0.75 g of a 1% aqueous solution of sodium hydrogen sulfite.
When 5 g was added and polymerized under stirring at 40 ° C. for 10 hours, a fine particle polymer dispersed in an aqueous salt solution was obtained.

The viscosity of this product is 2300 cp at 25 ° C, 1% of polymer 0.5%
The viscosity in N saline solution was 40.2 cp.

Example 2 In a separable flask used in Example 1, 7.5 g of a homopolymer of sodium 2-acrylamido-2-methylpropanesulfonate (purity 0.5%, viscosity is 20 cp at 25 ° C., 20 cp) 7.5 g, ammonium sulfate 100 g, and Ion-exchanged water (292.5 g) was added and dissolved, and acrylamide (75 g) was charged therein, and the mixture was heated to 45 ° C and purged with nitrogen.

Add 0.75 g of 1% ammonium persulfate aqueous solution,
% 0.72 g of sodium bisulfite aqueous solution is added and polymerized under stirring at 45 ° C. for 10 hours to obtain a fine particle polymer dispersed in an aqueous salt solution. The viscosity of this dispersion is 7500 at 25 ° C.
cp, the viscosity is 65c in 1N saline solution containing 0.5% polymer.
It was p.

When 25 g of diammonium hydrogen phosphate was further added to this dispersion, the viscosity decreased to 550 cp.

Example 3 In a separable flask used in Example 1, a homopolymer of sodium acrylate (purity: 0.5%, aqueous solution viscosity: 25 ° C.) was used.
10 cp) 2.5 g, 2.5 g of sodium 2-acrylamido-2-methylpropanesulfonate homopolymer (pure 0.5% aqueous solution viscosity is 30 cp) 2.5 g, ammonium sulphate 112.5 g and deionized water 332.5 g Acrylamide to this
43.6 g (90 mol%) and 6.4 g (10 mol%) of sodium acrylate were charged, and the mixture was heated to 45 ° C. and replaced with nitrogen.

To this, 1.5 g of 1% 2,2'-azobis (2-amidinopropane) hydrochloride aqueous solution was added and polymerized under stirring at 45 ° C for 10 hours to obtain a fine particle polymer dispersed in the salt aqueous solution. It was

The viscosity of this product is 3800 cp at 25 ° C, 1% of polymer 0.5%
The viscosity in N saline solution was 35.5 cp.

Example 4 In a separable flask used in Example 1, 7.5 g of a homopolymer of sodium 2-acrylamido-2-methylpropanesulfonate (purity 0.5% aqueous solution viscosity of 19 cp at 25 ° C.) 7.5 g, ammonium sulfate 106.3 g, Then, 310.5 g of ion-exchanged water was added and dissolved, and 51.5 g (90 mol%) of acrylamide, 23.5 g (10 mol%) of sodium 2-acrylamido-2-methylpropanesulfonate and benzyl as a chain transfer agent were dissolved in the solution. 0.75 g of alcohol was charged, the temperature was raised to 45 ° C., and the atmosphere was replaced with nitrogen.

To this, 2.3 g of 1% 2,2'-azobis (2-amidinopropane) hydrochloride aqueous solution was added and polymerized for 10 hours at 45 ° C with stirring to obtain a fine particle polymer dispersed in the salt aqueous solution. It was

The viscosity of this product is 1500 cp at 25 ° C, 1% of polymer 0.5%
The viscosity in N saline solution was 25 cp.

Example 5 In the separable flask used in Example 1, a homopolymer of sodium acrylate (0.5% pure solution in water has a viscosity of 25 ° C.).
7.5 g, ammonium sulfate 51 g, diammonium hydrogen phosphate 34 g, and ion-exchanged water 331.8 g were added and dissolved. Acrylamide 57.6 g (90 mol%), sodium acrylate 4.2 g (5 mol%) , Sodium 2-acrylamido-2-methylpropanesulfonate (13.2 g, 5 mol%) and isopropyl alcohol (0.75 g) as a chain transfer agent were charged, and the mixture was heated to 40 ° C. and replaced with nitrogen.

To this, 1.5g of 1% ammonium persulfate aqueous solution, 1%
1.5 g of sodium bisulfite aqueous solution was added and stirred under 40
Polymerization at 10 ° C. for 10 hours gave a fine particle polymer dispersed in an aqueous salt solution.

The viscosity of this product is 1030 cp at 25 ° C and 1% of polymer 0.5%
The viscosity in N saline solution was 30 cp.

Example 6 In a separable flask used in Example 1, 3.8 g of homopolymer of acryloyloxyethyltrimethylammonium chloride (purity 0.5% aqueous solution viscosity is 20 cp at 25 ° C.), 51 g of aluminum sulfate, 34 g of sodium sulfate, and Add 336.2 g of ion-exchanged water and dissolve, and add 75 g of acrylamide to this.
Was charged, heated to 50 ° C. and purged with nitrogen.

To this, 1.5 g of 1% 2,2'-azobis (2-amizonopropane) hydrochloride aqueous solution was added and polymerized for 10 hours at 50 ° C under stirring to obtain a fine particle polymer dispersed in the salt aqueous solution. Was given.

The viscosity of this product is 4100 cp at 25 ° C and 1% of polymer 0.5%
The viscosity in N saline solution was 55 cp.

Example 7 In the separable flask used in Example 1, a homopolymer of methacryloyloxyethyltrimethylammonium chloride (purity 0.5%, aqueous solution viscosity: 100 cp at 25 ° C.) 3.
8 g, ammonium sulfate 106.3 g, and ion-exchanged water 314.9 g
Was added and dissolved, and 56.6 g (90 mol%) of acrylamide and 18.4 g (10 mol%) of methacryloyloxyethyltrimethylammonium chloride were charged into the solution, and the mixture was heated to 45 ° C. and replaced with nitrogen.

To this, 1.5g of 1% ammonium persulfate aqueous solution, 1%
1.5 g of sodium bisulfite aqueous solution was added and stirred for 45
Polymerization at 10 ° C. for 10 hours gave a fine particle polymer dispersed in an aqueous salt solution.

The viscosity of this product is 2550 cp at 25 ° C, 1% of polymer 0.5%
The viscosity in N saline solution was 20.3 cp.

Comparative Example To the separable flask used in Example 1, 112.5 g of ammonium sulfate and 337.5 g of ion-exchanged water were added and dissolved, and 50 g of acrylamide was charged into this and heated to 40 ° C. to replace nitrogen.

0.5g of 1% ammonium persulfate aqueous solution and 0.5g of 1% sodium hydrogen sulfite aqueous solution were added to this, and the mixture was stirred at 40 ° C.
When polymerized with, the viscosity increased after 10 minutes and the whole became a lump.

(Effects of the Invention) (1) The properties of the product of the present invention produced in the example and that produced by ordinary aqueous solution polymerization were compared.

Thus, a product having a similar molecular weight was obtained as a product having low viscosity and fluidity as compared with the aqueous solution polymerized product.

Claims (6)

[Claims] 1. When polymerizing a water-soluble monomer (A) mainly comprising an acrylamide monomer while precipitating a polymer while stirring in an aqueous solution of a salt of an inorganic acid and / or an ammonium salt, A process for producing a free-flowing water-soluble polymer dispersion, which comprises allowing a polymer electrolyte (B) soluble in the salt aqueous solution to coexist. 2. A unit amount in which the water-soluble monomer (A) is acrylamide and the polymer electrolyte (B) is an alkali metal acrylate and / or an alkali metal 2-acrylamido-2-methylpropanesulfonic acid. Body unit from 30 to 100
The method for producing a water-soluble polymer dispersion according to claim 1, which is a polymer containing mol%. 3. The water-soluble monomer (A) is an alkali metal salt of (meth) acrylic acid and (meth) acrylamide, and (meth)
The alkali metal acrylate is a mixture of monomers of 15 mol% or less, and the polymer electrolyte (B) is composed of alkali metal acrylate and / or 2-acrylamido-2-methylpropanesulfonic acid alkali metal salt. Quantum unit
The method for producing a water-soluble polymer dispersion according to claim 1, which is a polymer containing 30 to 100 mol%. 4. The water-soluble monomer (A) is 2-acrylamido-2-methylpropanesulfonic acid alkali metal salt and (meth) acrylamide, and 2-acrylamido-2-methylpropanesulfonic acid alkali metal salt is 15 mol. % Or less of the monomer mixture, and the polymer electrolyte (B) is an alkali metal acrylate and / or 2-acrylamide-2.
A method for producing a water-soluble polymer dispersion according to claim 1, which is a polymer containing 30 to 100 mol% of a monomer unit consisting of an alkali metal salt of methylpropanesulfonic acid. 5. The water-soluble monomer (A) is acrylamide, and the polyelectrolyte (B) contains one or more cationic monomer units represented by the following formula (I) in an amount of 20 to 100.
The method for producing a water-soluble polymer dispersion according to claim 1, which is a polymer containing mol%. [Wherein R ₁ is H or CH ₃ ; R ₂ and R ₃ are alkyl groups having 1 to 2 carbon atoms; R ₄ is H or an alkyl group having 1 to 2 carbon atoms; A is an oxygen atom or NH; B is carbon Number 2 to 4 alkylene group or hydroxypropylene group; X ⁻ is an anionic counterion. ] 6. The water-soluble monomer (A) is one or more cationic monomers of the following formula (II), and (meth) acrylamide is the monomer of the formula (II) is 15 mol% or less. Wherein the polymer electrolyte (B) is a polymer containing 20 to 100 mol% of one or more of the cationic monomer units represented by the above formula (I). A method for producing a water-soluble polymer dispersion according to claim 1. [Wherein R ₁ is H or CH ₃ ; R ₂ and R ₃ are alkyl groups having 1 to ₃ carbon atoms; R ₄ is H or an alkyl group or alkanol group having 1 to 3 carbon atoms; X ⁻ is an anionic counterion Is. ]