RU1526158C - Method for stabilization of water soluble (co)polymers of acrylamide - Google Patents

Abstract

FIELD: chemistry of high molecular weight compound. SUBSTANCE: 0.0001-0.0025 mass of sodium salt of 2-mercaptobenzothiazole are added during preparing of monomer mass. Said process is carried out before polymerization of acrylamide or before its copolymerization together with acryl monomers. EFFECT: increases stability of aqueous solutions of polymers, retains their viscosity. 1 tbl

Description

 The invention relates to the chemistry of macromolecular compounds, namely to the production of polymers and copolymers based on acrylamide, used as flocculants, thickeners of water systems, soil builders, etc.

 The aim of the invention is to increase stability to thermal oxidative degradation of aqueous polymer solutions while maintaining their viscoelastic properties.

Example 1 40 ml of a 52% solution of acrylamide (AA), 56 ml of bidistilled water, 2 ml of a 0.01% solution of 2-mercaptobenzthiazole sodium are introduced into a reactor equipped with a stirrer and a nitrogen bubbler. salts (NS Office). Purge the reaction mixture with nitrogen for 30 minutes and introduce oxygen-free solutions of potassium persulfate (0.018% of acrylamide) and sodium metabisulfite (0.006% of acrylamide). Initial polymerisation temperature 30 ^C. After 2 hours the polymerization temperature reaches 78 ° ^C. The resultant gel is comminuted and dried at 100 ° ^C.

 Similarly, a powdery polymer is obtained without a stabilizing additive.

PRI me R 2. Analogously to example 1, the polymerization of the reaction mixture containing 38 ml of a 55% solution of acrylamide, 58 ml of bidistilled water, 0.5 ml of a 0.1% solution of sodium salt of 2-mercaptobenzthiazole, is carried out in the presence of 1.8 ml of 0.18% solution of potassium persulfate and 0.09 ml of 5% sodium 4,4-azobistsianpentanata ^at 25 ° C for 3 hours. The resulting polymer was ground and dried at 120 ° ^C. .

 In a similar way to obtain a polymer without a stabilizing additive.

PRI me R 3. In a reactor equipped with a bubbler for purging with nitrogen and a stirrer, enter 350 ml of a 1% solution of sorbital C-20 in toluene, 100 ml of a 50% aqueous solution of acrylamide, 0.5 ml 0, 01% aqueous solution of 2-mercaptobenzthiazole sodium salt, then after purging with nitrogen for 30 min, 1.5 ml of a 1% solution of potassium persulfate and 0.8 ml of a 1% solution of sodium metabisulfite are introduced. After completion of the polymerization, the resulting suspension is heated to 65 ^about C and 80% water is distilled off by azeotropic distillation. The azeotropic mixture is captured in a condenser, where it is delaminated, and toluene is returned to the reactor. The resulting suspension is filtered, the polymer is dried at 80-100 ^about C.

 Similarly, a polymer is obtained without a stabilizing additive.

 PRI me R 4. In a reactor equipped with a bubbler for purging with nitrogen and a stirrer, enter 400 ml of a 0.50% solution of sorbital C-20 in toluene, 50 ml of a 50% aqueous solution of acrylamide and 50 ml of 50% aqueous solution of acrylic acid (pH 8), 0.5 ml of a 0.01% aqueous solution of 2-mercaptobenzthiazole sodium salt, then after purging with nitrogen for 2 minutes, 2 ml of a 1% solution of potassium persulfate and 1, 0 ml of 1% sodium metabisulfite solution.

After completion of the polymerization, the resulting suspension is heated to 65 ^about C and 80% water is distilled off by azeotropic distillation.

The azeotropic mixture is captured in a condenser, where it is delaminated and the toluene is returned to the reactor. The resulting suspension is filtered, the polymer is dried at 80-100 ^about C.

 Similarly, a polymer is obtained without a stabilizing additive.

Example 5. 10 g of dimethylaminoethyl methacrylate quaternized with dimethyl sulfate, 30 ml of a 5% aqueous solution of acrylamide, 0.5 ml of a 0.05% aqueous solution are introduced into a reactor equipped with a stirrer and a nitrogen bubbler. solution of sodium salt of 2-mercapto-benzothiazole. 68 ml of double-distilled water and purged with nitrogen with stirring for 30 minutes. After purging, aqueous solutions of potassium persulfate and sodium metabisulfite 1 ml of 0.36% and 0.5 ml of 0.25%, respectively, are introduced into the reaction mass. Initial polymerisation temperature of 25 ^C. After polymerization for 4 hours the resulting gel was ground and dried at 100-120 ° ^C.

 Similarly, a polymer is obtained without a stabilizing additive.

PRI me R 6 (control). Analogously to example 1, in a solution obtained by mixing 60 ml of a 50% aqueous solution of acrylamide and 33 ml of double-distilled water, 0.5 ml of a 0.3% solution of sodium salt of 2-mercaptobenzthiazole is introduced, after purging with nitrogen, oxygen-free solutions of potassium persulfate (0 , 02% of acrylamide) and sodium 4,4'-azobiscyanopentanate (0.02% of acrylamide). Polymerization runs at ²⁰ ° C for 8 hours. The resulting gel was granulated in an extruder, the granules were dried at 100-120 ^C to a residual moisture content of 10-15 wt.

 In a similar way to obtain a polymer without a stabilizing additive.

PRI me R 7 (control). Analogously to example 1, the polymerization of 300 ml of a 50% solution of acrylamide is carried out in the presence of 0.00001% (to acrylamide) of 2-mercaptobenzthiazole sodium salt, 0.018% (to acrylamide) potassium persulfate and 0.006% (to acrylamide) sodium metabisulfite. The resulting polymer is crushed and dried at 120 ^about C. Similarly, the polymer is obtained without a stabilizing additive.

PRI me R 8 (comparative). In a flask equipped with a nitrogen bubbler and stirrer, 100 ml of a 10% solution of acrylamide are charged, purged with nitrogen for 30 minutes, and 1.7 g of potassium sulfate are introduced. The polymerization was carried out at 40 ^{° C} for 5 hours. A viscous aqueous polymer solution.

To the resulting polymer solution (500 ml), 0.5 g of 2-mercaptobenzthiazole sodium salt was added, stirred, after which the polymer was precipitated in 1500 ml of methanol. The polymer precipitate is filtered off, washed with methanol and dried in a vacuum dryer at 40 ^about C.

 The remaining half of the polyacrylamide solution is also mixed with methanol, the polymer is filtered off and dried in the same way.

 The resulting polymers are dissolved in water (from the calculation to obtain 0.05% solutions) and tested for stability properties.

Assessment of the stability of polymer solutions and thermal oxidative degradation is carried out by a test method. According to the test preparing aqueous polymer solutions of 0.1% concentration and maintained at 50 ^{° C} for 28 days. Selected conditions thermooxidative degradation of polymers are determined by the application in different industrial processes at elevated temperatures (100 ° ^C) over a large period of time (ranging from several hours to several months).

The stability of polymer solutions to thermo-oxidative degradation is characterized by a coefficient (K _η ) equal to the ratio of the reduced viscosity values of polymer solutions after storage (η _pr. ) To the initial (η _pr ^o ).

A reduced viscosity of 0.05% polymer solution is determined on an Ubbelohde capillary viscosimeter with a capillary diameter of 0.54 mm at 25 ^C. The solvent used is 10% solution of NaCl. According to consumer requirements for the polymer K _η must be at least 1.

The stability of the viscoelastic properties of the polymers is characterized by a coefficient K _SF equal to the ratio of the screen factor after storage (SF) to the initial one (SF ^о ). The screen factor is determined by the expiration time of a 0.03% polymer solution on a screen viscometer. The solvent used is an aqueous solution containing 0.18 g / l CaCl ₂ and 0.14 g / l NaCl. According to customer requirements for polymer K _SF must be at least 0.8.

 A comparative analysis of the stability to thermal oxidative degradation and the viscoelastic properties of aqueous solutions of acrylamide polymers is given in the table.

Claims (1)

 METHOD FOR STABILIZING WATER-SOLUBLE (CO) POLYMERS OF ACRYLAMIDE by introducing the sodium salt of 2-mercaptobenzothiazole, characterized in that, in order to increase the stability to thermooxidative degradation of aqueous polymer solutions while maintaining their viscoelastic properties, the 2-mercaptone solution salt is added with polymerization in an amount of 0.0001-0.0025% by weight of acrylamide.

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