JP2704735B2 - Method for producing water-soluble high molecular weight polymer - Google Patents

Description

The present invention relates to a method for producing a water-soluble polymer used in the fields of a polymer flocculant, a thickener, a petroleum recovery agent, a papermaking aid, and the like. More specifically, the present invention relates to a method for efficiently producing a high-molecular weight water-soluble polymer from a water-soluble vinyl monomer using a specific polymerization initiator.

[Prior art] As a water-soluble polymer used as a polymer flocculant, a petroleum recovery polymer, a papermaking aid, or the like, a high molecular weight polymer is particularly preferred because it exhibits excellent effects.

Conventionally, as a method for obtaining a high molecular weight polymer from a water-soluble vinyl monomer, for example, an acrylic monomer, a method of reducing the amount of a catalyst used in an aqueous solution and a method of polymerizing at a low monomer concentration have been adopted.

However, the method of reducing the amount of the catalyst has the disadvantage that the polymerization time is prolonged and an insoluble polymer is formed, resulting in poor water solubility. Further, in the method of lowering the monomer concentration, it is necessary to remove a large amount of solvent and to dry the polymer when the polymerization time is prolonged and the polymer is isolated at the same time as a granular product. Accordingly, the production capacity is reduced, and the production cost is increased due to the drying process.

A method of obtaining a water-soluble polymer by performing polymerization in a water-in-oil emulsion system of a water-soluble monomer aqueous solution and a water-insoluble solvent containing a surfactant and a catalyst has also been adopted. A similar problem arises when coalescence is to be obtained, with the disadvantage that the polymerization time is long and the product concentration is low, which is economically disadvantageous.

[Problems to be Solved by the Invention] Accordingly, an object of the present invention is to obtain a high-molecular-weight and water-soluble vinyl monomer polymer by lowering the monomer concentration or lengthening the polymerization time to improve productivity. Eliminate the drawbacks of traditional methods of lowering and increasing costs,
It is an object of the present invention to provide a production method for efficiently obtaining a high molecular weight water-soluble vinyl polymer.

[Means for Solving the Problems] The present inventors have conducted various studies on a method for producing a water-soluble high-molecular-weight vinyl polymer in order to solve the above-mentioned problems. It has been found that by using a redox catalyst combined with an agent as a polymerization initiator, a polymer having a shorter polymerization time, a higher molecular weight and good water solubility can be obtained as compared with the conventional method, and the present invention has been completed.

[Configuration of the Invention] Hereinafter, the configuration of the present invention will be described in detail.

Water-soluble monomer The water-soluble vinyl monomer to be subjected to the polymerization method in the present invention is a water-soluble monomer that is itself water-soluble, and is a monomer that produces a water-soluble polymer by polymerization, and a monomer having a water-soluble substituent and For salts.

Specific examples include (meth) acrylamide, N, N-dimethylacrylamide, (meth) acrylic acid, 2-acrylamido-2-methylpropanesulfonic acid, vinylsulfonic acid, styrenesulfonic acid, itaconic acid, and 2- (meth) acrylic acid. Acryloyloxyethyl dimethyl ammonium, 3
-(Meth) -acryloyloxypropyldimethylammonium, 3- (meth) acryloyloxy-2-hydroxypropyldimethylammonium, 3- (meth) -acrylamidopropyldimethylammonium, 2- (meth) -acryloylaminoethyldimethylammonium, 3 -(Meth) -acryloylamino-2-hydroxypropyldimethylammonium, dimethyldiallylammonium chloride and the like.

Examples of the type of salts of the water-soluble vinyl monomer include metal salts such as sodium and potassium and ammonium salts as anionic monomers, and quaternary salts of methyl chloride, dimethyl sulfate and benzyl chloride as cation monomers.
Grade salts, sulfuric acid tertiary salts, hydrochloric acid tertiary salts and the like.

These monomers can be used alone, or two or more of them can be used in combination as long as the resulting polymer becomes water-soluble. For example, a combination of a cationic monomer and an anionic monomer in which the resulting polymer is an amphoteric polymer is also possible as long as the solubility of the polymer is not impaired.

Other Monomers Further, other monomers copolymerizable with the above monomers can be used in combination. However, the amount of other monomers used must be within a range that does not impair the water solubility of the polymer. Examples of such other monomers include (meth) acrylonitrile, (meth) acrylate, styrene and the like.

Polymerization Initiator The polymerization initiator used in the method of the present invention is a redox initiator obtained by combining a bifunctional organic peroxide and a reducing agent.

The bifunctional organic peroxide has the following formula (I) Wherein R ₁ , R ₂ , R ₄ and R ₅ are independent of each other and are hydrogen, methyl, ethyl or propyl, R ₃ is a single bond, CH ₂ —CH _{2 n} Group (wherein, n is 1 to 3)
Is an integer. ) Or a phenylene group. And the following formula (II) Wherein R ₆ and R ₇ are independent of each other and are hydrogen, methyl, ethyl or propyl. Selected from one or more compounds represented by the formula:

Specific examples include 2,5-dimethylhexane-2,5-dihydroperoxide, diisopropylbenzene dihydroperoxide, cyclohexanone peroxide, methylcyclohexanone peroxide, 3,3,5-
Trimethylcyclohexanone peroxide and the like.

These are known compounds, and commercially available products can be obtained or can be produced by known methods.
In the present invention, these compounds can be used not only in a purified state but also in a product containing impurities such as a hydroxide.

As the reducing agent, sodium sulfite, potassium hydrogen sulfite, potassium sulfite, sodium pyrosulfite, ferrous sulfate, tertiary amine and the like usually used in a redox system are used.

The amounts of the peroxide and the reducing agent are usually about 0.0001 to 0.1% by weight, preferably 0.001 to 0.1%, respectively, based on all monomers.
05% by weight is desirable.

In the method of the present invention, a redox-based initiator comprising a bifunctional organic peroxide and a reducing agent is used in combination with a conventionally used initiator such as an oxidizing agent, a monofunctional organic peroxide and / or an azo-based catalyst. May be.

Specific examples of the oxidizing agent include potassium persulfate, ammonium persulfate, hydrogen peroxide, tertiary butyl hydroperoxide, and the like, and azo-based catalysts include 2,2 ′ azobis-2-amidinopropane hydrochloride and 2,2 ′. -Azobis-2- (5-methyl-2-imidazolin-2-yl) propane hydrochloride, 2,2'-azobisisobutyronitrile,
2,2'-azobis- (2,4-dimethylvaleronitrile) and the like.

[Polymerization Method] The method for polymerizing the above monomer according to the present invention includes an aqueous solution polymerization method and a water-in-oil emulsion polymerization method.

Aqueous solution polymerization method The above monomers are dissolved in water, and a chain transfer agent is optionally used,
After adding an additive such as a chelating agent, purge with an inert gas such as nitrogen to remove oxygen. The concentration of the monomer depends on the type of the monomer, but is usually 10 to 80% by weight, preferably 25% by weight.
~ 70%.

In the polymerization method, after the degassed monomer solution is cooled to -10 to 20 ° C, preferably -5 to 10 ° C, a reducing agent aqueous solution and an organic peroxide solution are added to the monomer aqueous solution and mixed to start polymerization.

Since organic peroxides are not usually dissolved in water, they are dissolved in a small amount of an organic solvent and added. The organic solvent used is selected from methanol, ethanol, isopropanol and the like.

The polymerization usually starts with an induction period of a few minutes to 1 hour and the temperature rises. The polymerization is carried out with heat insulation or cooling. Usually 1
In a period of time from 7 to 7 hours, the heat generation ends, the polymerization is completed, and a desired high molecular weight water-soluble polymer is obtained.

The polymer is in the form of a gel, and is crushed by ordinary physical means, cutting mill, meat chopper and other means, and then dried. Usually, dried to about 10% moisture, and further crushed to obtain a product having a uniform particle size. .

Water-in-oil emulsion polymerization method The initiator system according to the present invention can also be used for water-in-oil emulsion polymerization and the like.

As a method, first, a monomer aqueous solution is prepared, and a bifunctional organic peroxide dissolved in an organic solvent such as alcohol is added to this. On the other hand, a water-insoluble organic solvent containing a surfactant is separately prepared, the aqueous solution is dispersed therein, and emulsified to a particle diameter of about 0.3 to 20 μm using a homogenizer or the like.

This emulsion is purged with an inert gas such as nitrogen to remove oxygen. As the polymerizable monomer, the same monomer as in the aqueous solution polymerization method can be used, and the concentration of the aqueous solution of the vinyl monomer varies depending on the type of the monomer, but is 20 to 80% by weight, preferably 30 to 70% by weight.

As the water-insoluble organic solvent, those commonly used for reverse-phase polymerization of aliphatic, alicyclic or aromatic hydrocarbons, chlorinated hydrocarbons and the like are used alone or in combination.

A surfactant having an HLB value of 4 to 6 is used as a surfactant for emulsification. For example, sorbitan monostearate, sorbitan monooleate, glyceryl monooleate, ethoxylated aliphatic alcohol and the like can be mentioned.

The amount of the water-in-oil emulsifier to be used is usually 0.1 to 10% by weight, preferably 0.5 to 5% by weight of the weight of the aqueous monomer solution.

The weight ratio of the continuous phase to the dispersed monomer aqueous solution is 1
-4, but usually 2-3 is preferred.

The bifunctional organic peroxide according to the invention is usually present in an amount of from 0.001 to 0.5% by weight, preferably from 0.005 to 0.10 w
t% is added.

The peroxide is dissolved in an organic solvent such as alcohol and added to an aqueous solution before emulsification or an emulsion after emulsification.

The polymerization is usually started by adding an aqueous solution of a reducing agent. The polymerization temperature is not particularly limited, but is usually 20 to 70 ° C, preferably 30 to 60 ° C. The reaction temperature is usually cooled to keep it constant.

The conversion of the polymerization can be tracked by various methods. For example, a method of analyzing a double bond during polymerization is easily used. After the completion of the polymerization, a surfactant for promoting water dispersibility is added if necessary. The amount added is usually
It is 0.5 to 7% by weight, preferably 1 to 3% by weight.

[Effect of the Invention] According to the method for polymerizing a water-soluble vinyl monomer of the present invention,
A polymer having a higher molecular weight and better water solubility, which cannot be obtained by the conventional technology, can be obtained, and a very economical effect can be obtained.

[Examples] Hereinafter, the present invention will be further described with reference to examples, but the present invention is not limited to the following examples.

Example 1 Acrylamide / sodium acrylate (80/20 molar ratio)
Was placed in a 1 kg insulated glass bottle, purged with nitrogen, and cooled to 0 ° C. Then, 0.005 g of 2,5-dimethylhexane-2,5-dihydroperoxide dissolved in 1 ml of methanol and sodium sulfite 0.0
A solution prepared by dissolving 05 g in 1 ml of water was added and stirred. The polymerization started immediately and reached a maximum temperature after 65 minutes.

After the polymerization is completed, take out the gel and use a cutter for 2-3 mm
, And dried at a drying temperature of 60 ° C to 100 ° C, and crushed to obtain a powdered product. The water solubility and intrinsic viscosity of the obtained polymer were measured by the following methods.

1) Water solubility: A 0.1% distilled aqueous solution is prepared, filtered through a wire gauze, and visually judged. Evaluation criteria: ○: no insoluble content △: slight insoluble content ×: countless insoluble components 2) [η]: Intrinsic viscosity 30 ° C Measured with a 1N-NaNO ₃ solution using an Ubbelohde viscometer.

Example 2 A mixture of 1 kg of the same aqueous monomer solution as in Example 1 and 0.3 g of 2,2'-azobis-2-amidinopropane hydrochloride was placed in an insulated glass bottle, purged with nitrogen, and cooled to 0 ° C. 0.001 g of diisopropylbenzene dihydroperoxide dissolved in 1 ml of methanol, 0.001 g of potassium persulfate dissolved in 1 ml of water, 0.002 g of ferrous sulfate
g was dissolved in 1 ml of water, and the mixture was stirred. The polymerization started immediately and reached a maximum temperature after 75 minutes.

After completion of the polymerization, a powdery polymer was obtained in the same manner as in Example 1, and the physical properties were measured.

 Table 1 shows the results.

Comparative Example 1 The same operation as in Example 2 was performed, except that 0.002 g of potassium persulfate was dissolved in 1 ml of water instead of diisopropylbenzene dihydroperoxide.

The polymerization started immediately and reached a maximum temperature after 140 minutes. A powdery polymer was obtained in the same manner as in Example 2, and the physical properties were measured.

 Table 1 shows the results.

Example 3 Acrylic amide (75.6 g) and acrylic acid (18.9 g) were added to an inner volume of 50.
It was taken in a 0 ml separable flask and dissolved in 118 g of ion-exchanged water. While stirring to keep the internal temperature at 40 ° C. or lower, 10.5 g of granular NaOH was added for neutralization.

To this, a solution prepared by dissolving 0.02 g of 2,5-dimethylhexane-2,5-dihydroperoxide in 0.1 ml of methanol was added.

On the other hand, an oil phase was prepared by dissolving 8.9 g of span 80 (sorbitan monooleate) in 56 g of a straight-chain aliphatic hydrocarbon, and the above aqueous monomer phase was emulsified and emulsified. After removing, polymerization was carried out while maintaining the internal temperature at 40 ° C and adding a 0.5% aqueous sodium sulfite solution as a reaction initiator. The reaction rate of the polymerization was monitored by analyzing the double bond, and the reaction was terminated when a reaction rate of 99.5% or more was confirmed. The polymerization time was 1 hour and 40 minutes. After the polymerization was completed, 5 g of nonylphenol ethylene oxide adduct was added to improve the water dispersibility.

The obtained emulsion polymer (polymer content 34.3wt
%) Was dissolved in a distilled water solution having a polymer content of 0.1%, and the water solubility and intrinsic viscosity were measured in the same manner as in Example 1.

 Table 2 shows the results.

Example 4 In the same manner as in Example 3, a solution prepared by dissolving 0.015 g of cyclohexanone peroxide in 0.1 ml of acetone as a bifunctional organic peroxide was added to the aqueous phase, and polymerization was carried out in the same manner as in Example 3. However, 0.5% sodium bisulfite was used as a reducing agent. The polymerization time was 2 hours. Example 3
Physical properties were measured in the same manner as described above.

 Table 2 shows the results.

Comparative Example 2 In the same manner as in Example 3, 0.1 ml of tert-butyl hydroperoxide (0.02 g) was used as a monofunctional organic peroxide.
The solution dissolved in acetone was added to the aqueous phase, and polymerization was carried out in the same manner as in Example 3. The polymerization time was 2.5 hours.
Physical properties were measured in the same manner as in Example 3.

 Table 2 shows the results.

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor: Hikotada Tsuboi 1900 Togo, Mobara-shi, Chiba Mitsui Sia Namid Co., Ltd. (JP, A) JP-A-55-152739 (JP, A)

Claims (4)

(57) [Claims] 1. An aqueous monomer solution containing (a1) 10% by weight or more of a water-soluble vinyl monomer or (a2) an aqueous monomer solution containing 20% by weight or more of a water-soluble vinyl monomer is suspended or emulsified in a water-insoluble organic solvent. (B) adding a redox catalyst comprising a combination of a bifunctional organic peroxide and a reducing agent as a polymerization initiator to the water-in-oil emulsion, thereby polymerizing the water-soluble vinyl monomer. A method for producing a high molecular weight polymer. 2. A compound of the formula (I) Wherein R ₁ , R ₂ , R ₄ and R ₅ are independent of each other and are hydrogen, methyl, ethyl or propyl, R ₃ is a single bond, CH ₂ —CH _{2 n} Group (wherein, n is 1 to 3)
Is an integer. ) Or a phenylene group. And the following formula (II) Wherein R ₆ and R ₇ are independent of each other and are hydrogen, methyl, ethyl or propyl. The method according to claim 1, wherein the compound is selected from one or more of the compounds represented by the formula: 3. The method according to claim 1, wherein the water-soluble vinyl monomer is polymerized in an aqueous solution. 4. The method according to claim 1, wherein an aqueous solution of a water-soluble vinyl monomer is suspended or emulsified in a water-insoluble organic solvent and polymerized.