Hydroxymethylated polyacrylamide processing technology

Abstract

The invention relates to the field of hydroxymethylated polyacrylamide, in particular to a hydroxymethylated polyacrylamide processing technology which is used for solving the problems that traditional hydroxymethylated polyacrylamide is poor in salt tolerance, so that the viscosity of the traditional hydroxymethylated polyacrylamide is easy to greatly decrease and even loses activity in a high-salt-concentration environment, and the salt tolerance of the traditional hydroxymethylated polyacrylamide is poor. And application requirements in some specific fields are difficult to meet. According to the processing technology, acrylamide, N-hydroxymethyl acrylamide, a zwitterionic monomer and perfluorooctyl ethyl acrylate are used as polymerization monomers to carry out polymerization reaction, so that the prepared hydroxymethylated polyacrylamide can be used as a thickening agent to be applied to fracturing fluid and drilling fluid in oil and gas field exploitation; and fluid thickening and stabilization in the industrial fields of water treatment, papermaking, textile and the like. According to the present invention, under the conditions of high salt, high temperature and high shear force, the excellent thickening property and the excellent stability can be maintained, the viscosity of the fluid can be improved, and the flowing property of the fluid can be improved, such that the high cost performance and the wide application prospect can be provided in the practical application.

Description

Technical Field

[0001] The invention relates to the field of hydroxymethylated polyacrylamide, and in particular to a processing technology of hydroxymethylated polyacrylamide. Background Art

[0002] Polyacrylamide is a commonly used water-soluble polymer compound. Due to its excellent viscoelasticity, water absorption, hydrogel-forming ability and other characteristics, it is widely used in various fields, such as oil and gas field exploitation, water treatment, geological engineering, textile finishing, papermaking processing, etc. Hydroxymethylated polyacrylamide is a hydroxylated polyacrylamide. The introduction of hydroxyl groups in its structure makes it have stronger hydrophilic properties, better biocompatibility and more stable performance. This makes hydroxymethylated polyacrylamide show better effects in the above-mentioned application fields. However, while traditional hydroxymethylated polyacrylamide has excellent water solubility, it also has the disadvantage of insufficient salt resistance. In a high salt concentration environment, the viscosity is easily greatly reduced, or even loses activity, which makes it difficult to meet the application requirements of certain specific fields under high salt conditions. Therefore, it is of great significance to develop a processing technology for hydroxymethylated polyacrylamide with excellent salt resistance. Summary of the invention

[0003] In order to overcome the above technical problems, the purpose of the present invention is to provide a processing technology for hydroxymethylated polyacrylamide: by reacting dodecane bromide and N-methylethanolamine, the bromine atom on dodecane bromide reacts with the NH on the N-methylethanolamine to introduce a long carbon chain, and at the same time, the secondary amine group is converted into a tertiary amine group to obtain an intermediate 1, and then the intermediate 1 is reacted with methacrylic acid, and the hydroxyl group on the intermediate 1 reacts with the carboxyl group on the methacrylic acid to form an ester group to obtain an intermediate 2, and then the intermediate 2 is reacted with sodium chloroacetate, and the tertiary amine group on the intermediate 2 reacts with the chlorine atom on the sodium chloroacetate to convert the tertiary amine group into a quaternary ammonium cationic group, and at the same time, a sodium carboxylate anion group is introduced to obtain a zwitterionic monomer, and finally acrylamide, N-hydroxymethyl acrylamide, a zwitterionic monomer, and perfluorooctyl ethyl acrylate are used as polymerization monomers to carry out a polymerization reaction to form a polymer to obtain hydroxymethylated polyacrylamide, which solves the problem that the traditional hydroxymethylated polyacrylamide has insufficient salt resistance, resulting in a significant decrease in viscosity and even loss of activity in a high salt concentration environment, making it difficult to meet the application requirements of certain specific fields.

[0004] The purpose of the present invention can be achieved through the following technical solutions:

[0005] A hydroxymethylated polyacrylamide processing technology comprises the following steps:

[0006] Step 1: Add dodecane bromide, N-methylethanolamine and isopropanol to a three-necked flask equipped with a stirrer, a thermometer, an air guide tube and a reflux condenser, introduce nitrogen protection, stir the reaction for 20-30 minutes at a temperature of 25-30°C and a stirring rate of 300-400r / min, then heat the temperature to reflux and continue stirring the reaction for 3-5 hours. After the reaction is completed, the reaction product is cooled to room temperature, and then the solvent is removed by rotary evaporation, and then added to methyl tert-butyl ether, and then washed with saturated brine 2-3 times, and then dried with anhydrous sodium sulfate, and then vacuum filtered, and the filtrate is rotary evaporated to remove the solvent to obtain intermediate 1;

[0007] Step 2: Add intermediate 1 and dichloromethane to a three-necked flask equipped with a stirrer, a thermometer and an air guide tube, introduce nitrogen protection, stir and react for 20-30 minutes at a temperature of 25-30° C. and a stirring rate of 300-400 r / min, then add EDCI condensing agent, 4-dimethylaminopyridine and methacrylic acid in sequence and continue to stir and react for 3-5 hours. After the reaction is completed, wash the reaction product with distilled water and saturated brine in sequence for 2-3 times, then dry it with anhydrous sodium sulfate, and then vacuum filter it, and rotary evaporate the filtrate to remove the solvent to obtain intermediate 2;

[0008] Step 3: Add intermediate 2, sodium chloroacetate, hydroquinone and deionized water to a three-necked flask equipped with a stirrer, a thermometer and an air guide tube, introduce nitrogen protection, stir the reaction at a temperature of 25-30°C and a stirring rate of 300-400r / min for 20-30min, then heat to 65-70°C and continue stirring the reaction for 3-5h. After the reaction is completed, cool the reaction product to room temperature, then rotary evaporate to remove the solvent, then add it to a mixed solvent, then vacuum filter, rotary evaporate to remove the solvent, and obtain a zwitterionic monomer;

[0009] Step 4: Add acrylamide, N-hydroxymethyl acrylamide, zwitterionic monomer, perfluorooctyl ethyl acrylate, sodium dodecyl sulfonate and deionized water to a three-necked flask equipped with a stirrer, a thermometer, an air guide tube and a constant pressure dropping funnel, introduce nitrogen protection, stir and react for 20-30 minutes at a temperature of 25-30°C and a stirring rate of 300-400r / min, then adjust the pH to 7-8 with sodium hydroxide solution, then add the initiator solution dropwise while stirring, control the dropping rate to 1-2 drops / s, continue to stir and react for 3-4 hours after the dropwise addition is completed, and after the reaction is completed, the reaction product is rotary evaporated to remove the solvent, and then washed with acetone and anhydrous ethanol 2-3 times in turn, and then placed in a vacuum drying oven, dried at a temperature of 40-45°C for 2-3 hours, and then crushed to obtain hydroxymethylated polyacrylamide.

[0010] As a further solution of the present invention: the dosage ratio of the brominated dodecane, N-methylethanolamine and isopropanol in step 1 is 10 mmol: 10 mmol: 30-40 mL.

[0011] As a further scheme of the present invention: the usage ratio of the intermediate 1, dichloromethane, EDCI condensation agent, 4-dimethylaminopyridine and methacrylic acid in step 2 is 10 mmol: 50-60 mL: 10 mmol: 1-3 mmol: 10-11 mmol.

[0012] As a further solution of the present invention: the dosage ratio of the intermediate 2, sodium chloroacetate, hydroquinone and deionized water in step three is 10 mmol: 12-16 mmol: 0.005-0.009 g: 40-50 mL.

[0013] As a further solution of the present invention: the mixed solvent in step 3 is a mixture of acetone and anhydrous ether in equal volumes.

[0014] As a further scheme of the present invention: the usage ratio of the acrylamide, N-hydroxymethyl acrylamide, zwitterionic monomer, perfluorooctyl ethyl acrylate, sodium dodecyl sulfonate, deionized water and initiator solution in step 4 is 20-25g:45-55g:4-16g:1-9g:0.01g:250-300mL:12-16mL.

[0015] As a further solution of the present invention: the mass fraction of the sodium hydroxide solution in step 4 is 15-25%.

[0016] As a further solution of the present invention: the initiator solution in step 4 is one of potassium persulfate solution and ammonium persulfate solution.

[0017] As a further solution of the present invention: the mass fraction of the initiator solution in step 4 is 2-3%.

[0018] Beneficial effects of the present invention:

[0019] The invention discloses a hydroxymethylated polyacrylamide processing process, wherein the bromine atom on the bromine dodecane reacts with the N- on the N-methylethanolamine to introduce a long carbon chain, and at the same time, the secondary amine group is converted into a tertiary amine group to obtain an intermediate 1, and then the intermediate 1 is reacted with methacrylic acid to react the hydroxyl group on the intermediate 1 with the carboxyl group on the methacrylic acid to form an ester group to obtain an intermediate 2, and then the intermediate 2 is reacted with sodium chloroacetate to react the tertiary amine group on the intermediate 2 with the chlorine atom on the sodium chloroacetate to convert the tertiary amine group into a quaternary ammonium cation group, and at the same time, a sodium carboxylate anion is introduced. The invention relates to a process for preparing polyacrylamide with acrylamide and N-hydroxymethyl acrylamide to obtain a zwitterionic monomer, and finally a polymerization reaction is carried out using acrylamide, N-hydroxymethyl acrylamide, a zwitterionic monomer and perfluorooctyl ethyl acrylate as polymerization monomers to form a polymer to obtain hydroxymethylated polyacrylamide. The processing technology uses acrylamide and N-hydroxymethyl acrylamide as main raw materials to form polyacrylamide containing hydroxymethyl. After introducing hydroxymethyl as a hydrophilic group into the molecular chain of polyacrylamide, its water solubility is further improved, so that it can be more evenly dispersed in water to form a more stable solution system, thereby enhancing the thickening effect and increasing the hydrogen bonding effect and Other intermolecular interactions make it easier for hydroxymethylated polyacrylamide molecules to entangle with each other in the solution, forming a tighter three-dimensional network structure, thereby improving the viscosity and thickening performance of the solution. Zwitterionic monomers are used as polymerization monomers to introduce quaternary ammonium cationic groups and sodium carboxylate anionic groups into the molecular chain of hydroxymethylated polyacrylamide, so that positive and negative charges exist on the molecular chain of hydroxymethylated polyacrylamide at the same time. These charges form a charge balance inside the molecule, which helps to reduce the charge shielding effect of the hydroxymethylated polyacrylamide molecular chain in a high salt environment, thereby maintaining the stability and decomposition of the hydroxymethylated polyacrylamide molecular chain. It not only increases the dispersion, but also increases the interaction between the hydroxymethylated polyacrylamide molecular chain and water molecules to form a stable hydration layer, which effectively blocks the corrosion of salt ions on the hydroxymethylated polyacrylamide molecular chain, thereby improving the salt resistance. Perfluorooctyl ethyl acrylate is used as a polymerization monomer to introduce a large number of fluorine atoms into the molecular chain of hydroxymethylated polyacrylamide. Fluorine atoms have lower surface energy and cohesive energy density, which endows hydroxymethylated polyacrylamide with stronger hydrophobic association, further enhancing the salt ion corrosion resistance of hydroxymethylated polyacrylamide, so that it can still maintain a high viscosity in a high salt environment, and also exhibits good temperature resistance.

[0020] In summary, the hydroxymethylated polyacrylamide prepared by the present invention can be used as a thickener in fracturing fluids and drilling fluids in oil and gas field exploitation, as well as in fluid thickening and stabilization in industrial fields such as water treatment, papermaking, and textiles. Under high salt, high temperature, and high shear conditions, the polymer can maintain excellent thickening performance and stability, increase fluid viscosity, and improve fluid flow properties, thereby showing higher cost performance and wider application prospects in practical applications. DETAILED DESCRIPTION

[0021] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] Embodiment 1:

[0023] This embodiment is a processing technology for hydroxymethylated polyacrylamide, comprising the following steps:

[0024] Step 1: add 10 mmol of bromododecane, 10 mmol of N-methylethanolamine and 30 mL of isopropanol into a three-necked flask equipped with a stirrer, a thermometer, an air guide tube and a reflux condenser, introduce nitrogen protection, stir and react for 20 min at a temperature of 25 ° C and a stirring rate of 300 r / min, then heat to reflux and continue stirring and reacting for 3 h. After the reaction is completed, the reaction product is cooled to room temperature, and then the solvent is removed by rotary evaporation, and then added to methyl tert-butyl ether, and then washed twice with saturated brine, and then dried over anhydrous sodium sulfate, and then vacuum filtered, and the filtrate is rotary evaporated to remove the solvent to obtain intermediate 1;

[0025] Step 2: 10 mmol of intermediate 1 and 50 mL of dichloromethane were added to a three-necked flask equipped with a stirrer, a thermometer and a gas guide tube, and nitrogen was introduced for protection. The reaction was stirred for 20 minutes at a temperature of 25° C. and a stirring rate of 300 r / min. Then, 10 mmol of EDCI condensing agent, 1 mmol of 4-dimethylaminopyridine and 10 mmol of methacrylic acid were added in sequence and the stirring reaction was continued for 3 hours. After the reaction was completed, the reaction product was washed twice with distilled water and saturated brine in sequence, and then dried with anhydrous sodium sulfate, and then vacuum filtered, and the filtrate was rotary evaporated to remove the solvent to obtain intermediate 2;

[0026] Step 3: 10 mmol of intermediate 2, 12 mmol of sodium chloroacetate, 0.005 g of hydroquinone and 40 mL of deionized water were added to a three-necked flask equipped with a stirrer, a thermometer and an air guide tube, and nitrogen was introduced for protection. The mixture was stirred at 25 ° C. and a stirring rate of 300 r / min for 20 min, and then the temperature was raised to 65 ° C. and the stirring reaction was continued for 3 h. After the reaction was completed, the reaction product was cooled to room temperature, and then the solvent was removed by rotary evaporation. Then, it was added to a mixed solvent of acetone and anhydrous ether mixed in equal volumes, and then vacuum filtered, and the solvent was removed by rotary evaporation to obtain a zwitterionic monomer;

[0027] Step 4: 20g acrylamide, 45g N-hydroxymethyl acrylamide, 4g zwitterionic monomer, 1g perfluorooctyl ethyl acrylate, 0.01g sodium dodecyl sulfate and 250mL deionized water are added to a three-necked flask equipped with a stirrer, a thermometer, an air guide tube and a constant pressure dropping funnel, and nitrogen is introduced for protection. The reaction is stirred for 20min at a temperature of 25°C and a stirring rate of 300r / min, and then the pH is adjusted to 7 with a mass fraction of 15% sodium hydroxide solution. Then, 12mL of a mass fraction of 2% potassium persulfate solution is added dropwise while stirring, and the dropping rate is controlled to 1 drop / s. After the dropwise addition is completed, the stirring reaction is continued for 3h. After the reaction is completed, the reaction product is rotary evaporated to remove the solvent, and then washed twice with acetone and anhydrous ethanol in turn, and then placed in a vacuum drying oven, dried at a temperature of 40°C for 2h, and then crushed to obtain hydroxymethylated polyacrylamide.

[0028] Embodiment 2:

[0029] This embodiment is a processing technology for hydroxymethylated polyacrylamide, comprising the following steps:

[0030] Step 1: 10 mmol of bromododecane, 10 mmol of N-methylethanolamine and 35 mL of isopropanol were added to a three-necked flask equipped with a stirrer, a thermometer, an air guide tube and a reflux condenser, and nitrogen was introduced for protection. The reaction was stirred for 25 min at a temperature of 28 ° C and a stirring rate of 350 r / min, and then the temperature was raised to reflux and the stirring reaction was continued for 4 h. After the reaction was completed, the reaction product was cooled to room temperature, and then the solvent was removed by rotary evaporation, and then added to methyl tert-butyl ether, and then washed twice with saturated brine, and then dried over anhydrous sodium sulfate, and then vacuum filtered, and the filtrate was rotary evaporated to remove the solvent to obtain intermediate 1;

[0031] Step 2: 10 mmol of intermediate 1 and 55 mL of dichloromethane were added to a three-necked flask equipped with a stirrer, a thermometer and a gas guide tube, and nitrogen was introduced for protection. The reaction was stirred for 25 minutes at a temperature of 28°C and a stirring rate of 350 r / min. Then, 10 mmol of EDCI condensing agent, 2 mmol of 4-dimethylaminopyridine and 10.5 mmol of methacrylic acid were added in sequence and the reaction was continued for 4 hours. After the reaction was completed, the reaction product was washed twice with distilled water and saturated brine in sequence, and then dried with anhydrous sodium sulfate, and then vacuum filtered. The filtrate was rotary evaporated to remove the solvent to obtain intermediate 2;

[0032] Step 3: 10 mmol of intermediate 2, 14 mmol of sodium chloroacetate, 0.007 g of hydroquinone and 45 mL of deionized water were added to a three-necked flask equipped with a stirrer, a thermometer and an air guide tube, and nitrogen was introduced for protection. The reaction was stirred for 25 minutes at a temperature of 28° C. and a stirring rate of 350 r / min, and then the temperature was raised to 68° C. and the stirring reaction was continued for 4 hours. After the reaction was completed, the reaction product was cooled to room temperature, and then the solvent was removed by rotary evaporation. Then, it was added to a mixed solvent of acetone and anhydrous ether mixed in equal volumes, and then vacuum filtered, and the solvent was removed by rotary evaporation to obtain a zwitterionic monomer;

[0033] Step 4: 22g acrylamide, 50g N-hydroxymethyl acrylamide, 10g zwitterionic monomer, 5g perfluorooctyl ethyl acrylate, 0.01g sodium dodecyl sulfate and 275mL deionized water are added to a three-necked flask equipped with a stirrer, a thermometer, an air guide tube and a constant pressure dropping funnel, and nitrogen protection is introduced. The reaction is stirred for 25min at a temperature of 28°C and a stirring rate of 350r / min, and then the pH is adjusted to 7.5 with a 20% mass fraction of sodium hydroxide solution, and then 14mL of a 2.5% mass fraction of potassium persulfate solution is added dropwise while stirring, and the dropping rate is controlled to 1 drop / s. After the dropwise addition is completed, the stirring reaction is continued for 3.5h. After the reaction is completed, the reaction product is rotary evaporated to remove the solvent, and then washed twice with acetone and anhydrous ethanol in turn, and then placed in a vacuum drying oven, dried at a temperature of 42°C for 2.5h, and then crushed to obtain hydroxymethylated polyacrylamide.

[0034] Embodiment 3:

[0035] This embodiment is a processing technology for hydroxymethylated polyacrylamide, comprising the following steps:

[0036] Step 1: add 10 mmol of bromododecane, 10 mmol of N-methylethanolamine and 40 mL of isopropanol into a three-necked flask equipped with a stirrer, a thermometer, an air guide tube and a reflux condenser, introduce nitrogen protection, stir the reaction for 30 min at a temperature of 30° C. and a stirring rate of 400 r / min, then heat the mixture to reflux and continue stirring the reaction for 5 h. After the reaction is completed, cool the reaction product to room temperature, then rotary evaporate to remove the solvent, then add it to methyl tert-butyl ether, then wash it 3 times with saturated brine, then dry it with anhydrous sodium sulfate, then vacuum filter it, and rotary evaporate the filtrate to remove the solvent to obtain intermediate 1;

[0037] Step 2: 10 mmol of intermediate 1 and 60 mL of dichloromethane were added to a three-necked flask equipped with a stirrer, a thermometer and a gas guide tube, and nitrogen was introduced for protection. The reaction was stirred for 30 minutes at a temperature of 30°C and a stirring rate of 400 r / min. Then, 10 mmol of EDCI condensing agent, 3 mmol of 4-dimethylaminopyridine and 11 mmol of methacrylic acid were added in sequence and the stirring reaction was continued for 5 hours. After the reaction was completed, the reaction product was washed three times with distilled water and saturated brine in sequence, and then dried with anhydrous sodium sulfate, and then vacuum filtered. The filtrate was rotary evaporated to remove the solvent to obtain intermediate 2;

[0038] Step 3: 10 mmol of intermediate 2, 16 mmol of sodium chloroacetate, 0.009 g of hydroquinone and 50 mL of deionized water were added to a three-necked flask equipped with a stirrer, a thermometer and an air guide tube, and nitrogen was introduced for protection. The mixture was stirred at a temperature of 30° C. and a stirring rate of 400 r / min for 30 min, and then the mixture was heated to 70° C. and continued to stir for 5 h. After the reaction was completed, the reaction product was cooled to room temperature, and then the solvent was removed by rotary evaporation. The mixture was then added to a mixed solvent of acetone and anhydrous ether in equal volumes, and then vacuum filtered and the solvent was removed by rotary evaporation to obtain a zwitterionic monomer;

[0039] Step 4: 25g acrylamide, 55g N-hydroxymethyl acrylamide, 16g zwitterionic monomer, 9g perfluorooctyl ethyl acrylate, 0.01g sodium dodecyl sulfate and 300mL deionized water are added to a three-necked flask equipped with a stirrer, a thermometer, an air guide tube and a constant pressure dropping funnel, and nitrogen protection is introduced. The reaction is stirred for 30 minutes at a temperature of 30°C and a stirring rate of 400r / min, and then the pH is adjusted to 8 with a 25% mass fraction of sodium hydroxide solution. Then, 16mL of a 3% mass fraction of ammonium persulfate solution is added dropwise while stirring, and the dropping rate is controlled to 2 drops / s. After the dropwise addition is completed, the stirring reaction is continued for 4h. After the reaction is completed, the reaction product is rotary evaporated to remove the solvent, and then washed with acetone and anhydrous ethanol 3 times in sequence, and then placed in a vacuum drying oven, dried at a temperature of 45°C for 3h, and then crushed to obtain hydroxymethylated polyacrylamide.

[0040] Comparative Example 1:

[0041] This comparative example is a hydroxymethylated polyacrylamide processing process, comprising the following steps:

[0042] 25g acrylamide, 55g N-hydroxymethyl acrylamide, 0.01g sodium dodecylsulfonate and 300mL deionized water were added to a three-necked flask equipped with a stirrer, a thermometer, an air guide tube and a constant pressure dropping funnel, and nitrogen was introduced for protection. The mixture was stirred and reacted for 30min at a temperature of 30°C and a stirring rate of 400r / min. Then, the pH was adjusted to 8 with a 25% mass fraction sodium hydroxide solution. Then, 16mL of a 3% mass fraction ammonium persulfate solution was added dropwise while stirring, and the dropping rate was controlled to 2 drops / s. After the dropwise addition was completed, the stirring reaction was continued for 4h. After the reaction was completed, the reaction product was rotary evaporated to remove the solvent, and then washed with acetone and anhydrous ethanol for 3 times in sequence. Then, it was placed in a vacuum drying oven and dried at a temperature of 45°C for 3h, and then crushed to obtain hydroxymethylated polyacrylamide.

[0043] Comparative Example 2:

[0044] This comparative example is a hydroxymethylated polyacrylamide processing process, comprising the following steps:

[0045] 25g acrylamide, 55g N-hydroxymethyl acrylamide, 9g perfluorooctyl ethyl acrylate, 0.01g sodium dodecyl sulfate and 300mL deionized water were added to a three-necked flask equipped with a stirrer, a thermometer, an air guide tube and a constant pressure dropping funnel, and nitrogen was introduced for protection. The mixture was stirred and reacted for 30min at a temperature of 30°C and a stirring rate of 400r / min. Then, the pH was adjusted to 8 with a 25% mass fraction sodium hydroxide solution. Then, 16mL of a 3% mass fraction ammonium persulfate solution was added dropwise while stirring, and the dropping rate was controlled to 2 drops / s. After the dropwise addition was completed, the stirring reaction was continued for 4h. After the reaction was completed, the reaction product was rotary evaporated to remove the solvent, and then washed with acetone and anhydrous ethanol for 3 times in sequence. Then, it was placed in a vacuum drying oven and dried at a temperature of 45°C for 3h, and then crushed to obtain hydroxymethylated polyacrylamide.

[0046] Comparative Example 3:

[0047] This comparative example is a hydroxymethylated polyacrylamide processing process, comprising the following steps:

[0048] Step 1: add 10 mmol of bromododecane, 10 mmol of N-methylethanolamine and 40 mL of isopropanol into a three-necked flask equipped with a stirrer, a thermometer, an air guide tube and a reflux condenser, introduce nitrogen protection, stir the reaction for 30 min at a temperature of 30° C. and a stirring rate of 400 r / min, then heat the mixture to reflux and continue stirring the reaction for 5 h. After the reaction is completed, cool the reaction product to room temperature, then rotary evaporate to remove the solvent, then add it to methyl tert-butyl ether, then wash it 3 times with saturated brine, then dry it with anhydrous sodium sulfate, then vacuum filter it, and rotary evaporate the filtrate to remove the solvent to obtain intermediate 1;

[0049] Step 2: 10 mmol of intermediate 1 and 60 mL of dichloromethane were added to a three-necked flask equipped with a stirrer, a thermometer and a gas guide tube, and nitrogen was introduced for protection. The reaction was stirred for 30 minutes at a temperature of 30°C and a stirring rate of 400 r / min. Then, 10 mmol of EDCI condensing agent, 3 mmol of 4-dimethylaminopyridine and 11 mmol of methacrylic acid were added in sequence and the stirring reaction was continued for 5 hours. After the reaction was completed, the reaction product was washed three times with distilled water and saturated brine in sequence, and then dried with anhydrous sodium sulfate, and then vacuum filtered. The filtrate was rotary evaporated to remove the solvent to obtain intermediate 2;

[0050] Step 3: 10 mmol of intermediate 2, 16 mmol of sodium chloroacetate, 0.009 g of hydroquinone and 50 mL of deionized water were added to a three-necked flask equipped with a stirrer, a thermometer and an air guide tube, and nitrogen was introduced for protection. The mixture was stirred at a temperature of 30° C. and a stirring rate of 400 r / min for 30 min, and then the mixture was heated to 70° C. and continued to stir for 5 h. After the reaction was completed, the reaction product was cooled to room temperature, and then the solvent was removed by rotary evaporation. The mixture was then added to a mixed solvent of acetone and anhydrous ether in equal volumes, and then vacuum filtered and the solvent was removed by rotary evaporation to obtain a zwitterionic monomer;

[0051] Step 4: 25g acrylamide, 55g N-hydroxymethyl acrylamide, 16g zwitterionic monomer, 0.01g sodium dodecyl sulfate and 300mL deionized water are added to a three-necked flask equipped with a stirrer, a thermometer, an air guide tube and a constant pressure dropping funnel, and nitrogen protection is introduced. The reaction is stirred for 30 minutes at a temperature of 30°C and a stirring rate of 400r / min, and then the pH is adjusted to 8 with a mass fraction of 25% sodium hydroxide solution. Then, 16mL of a mass fraction of 3% ammonium persulfate solution is added dropwise while stirring, and the dropping rate is controlled to 2 drops / s. After the dropwise addition is completed, the stirring reaction is continued for 4h. After the reaction is completed, the reaction product is rotary evaporated to remove the solvent, and then washed with acetone and anhydrous ethanol 3 times in sequence, and then placed in a vacuum drying oven, dried at a temperature of 45°C for 3h, and then crushed to obtain hydroxymethylated polyacrylamide.

[0052] The hydroxymethylated polyacrylamide of Examples 1-3 and Comparative Examples 1-3 was added to deionized water or 200 g / L NaCl solution to prepare a solution with a mass fraction of 1%, and the solution was tested at 30°C and 170 s. -1 The apparent viscosity after shearing for 120 minutes at the shear rate is shown in the following table:

[0053]

[0054] Referring to the data in the above table, based on the comparison between Examples 1-3 and Comparative Examples 1-3, it can be known that the hydroxymethylated polyacrylamide of the present application has high apparent viscosity and excellent salt resistance.

[0055] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0056] The above contents are merely examples and explanations of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the invention or exceed the scope defined by the claims, they shall all fall within the protection scope of the present invention.

Claims

1. A process for processing hydroxymethylated polyacrylamide, characterized in that: The following steps are involved: Step 1: Add dodecane bromide, N-methylethanolamine and isopropanol to a three-necked flask equipped with a stirrer, a thermometer, an air guide tube and a reflux condenser, introduce nitrogen protection, stir the reaction for 20-30 minutes at a temperature of 25-30°C and a stirring rate of 300-400r / min, then heat the temperature to reflux and continue stirring the reaction for 3-5 hours. After the reaction is completed, the reaction product is cooled to room temperature, and then the solvent is removed by rotary evaporation, and then added to methyl tert-butyl ether, and then washed with saturated brine 2-3 times, and then dried with anhydrous sodium sulfate, and then vacuum filtered, and the filtrate is rotary evaporated to remove the solvent to obtain intermediate 1; Step 2: Add intermediate 1 and dichloromethane to a three-necked flask equipped with a stirrer, a thermometer and an air guide tube, introduce nitrogen protection, stir and react for 20-30 minutes at a temperature of 25-30° C. and a stirring rate of 300-400 r / min, then add EDCI condensing agent, 4-dimethylaminopyridine and methacrylic acid in sequence and continue to stir and react for 3-5 hours. After the reaction is completed, wash the reaction product with distilled water and saturated brine in sequence for 2-3 times, then dry it with anhydrous sodium sulfate, and then vacuum filter it, and rotary evaporate the filtrate to remove the solvent to obtain intermediate 2; Step 3: Add intermediate 2, sodium chloroacetate, hydroquinone and deionized water to a three-necked flask equipped with a stirrer, a thermometer and an air guide tube, introduce nitrogen protection, stir the reaction at a temperature of 25-30°C and a stirring rate of 300-400r / min for 20-30min, then heat to 65-70°C and continue stirring the reaction for 3-5h. After the reaction is completed, cool the reaction product to room temperature, then rotary evaporate to remove the solvent, then add it to a mixed solvent, then vacuum filter, rotary evaporate to remove the solvent, and obtain a zwitterionic monomer; Step 4: Add acrylamide, N-hydroxymethyl acrylamide, zwitterionic monomer, perfluorooctyl ethyl acrylate, sodium dodecyl sulfonate and deionized water to a three-necked flask equipped with a stirrer, a thermometer, an air guide tube and a constant pressure dropping funnel, introduce nitrogen protection, stir and react for 20-30 minutes at a temperature of 25-30°C and a stirring rate of 300-400r / min, then adjust the pH to 7-8 with sodium hydroxide solution, then add the initiator solution dropwise while stirring, control the dropping rate to 1-2 drops / s, continue to stir and react for 3-4 hours after the dropwise addition is completed, and after the reaction is completed, the reaction product is rotary evaporated to remove the solvent, and then washed with acetone and anhydrous ethanol 2-3 times in turn, and then placed in a vacuum drying oven, dried at a temperature of 40-45°C for 2-3 hours, and then crushed to obtain hydroxymethylated polyacrylamide.

2. A hydroxymethylated polyacrylamide processing technology according to claim 1, characterized in that: The dosage ratio of the brominated dodecane, N-methylethanolamine and isopropanol in step 1 is 10 mmol: 10 mmol: 30-40 mL.

3. A hydroxymethylated polyacrylamide processing technology according to claim 1, characterized in that: The usage ratio of the intermediate 1, dichloromethane, EDCI condensation agent, 4-dimethylaminopyridine and methacrylic acid in step 2 is 10 mmol: 50-60 mL: 10 mmol: 1-3 mmol: 10-11 mmol.

4. A hydroxymethylated polyacrylamide processing technology according to claim 1, characterized in that: The usage ratio of the intermediate 2, sodium chloroacetate, hydroquinone and deionized water in step 3 is 10 mmol: 12-16 mmol: 0.005-0.009 g: 40-50 mL.

5. A hydroxymethylated polyacrylamide processing technology according to claim 1, characterized in that: The mixed solvent in step 3 is prepared by mixing acetone and anhydrous ether in equal volumes.

6. A hydroxymethylated polyacrylamide processing technology according to claim 1, characterized in that: The usage ratio of the acrylamide, N-hydroxymethyl acrylamide, zwitterionic monomer, perfluorooctyl ethyl acrylate, sodium dodecyl sulfonate, deionized water and initiator solution in step 4 is 20-25g:45-55g:4-16g:1-9g:0.01g:250-300mL:12-16mL.

7. A process for processing hydroxymethylated polyacrylamide according to claim 1, characterized in that: The mass fraction of the sodium hydroxide solution in step 4 is 15-25%.

8. A process for processing hydroxymethylated polyacrylamide according to claim 1, characterized in that: The initiator solution in step 4 is one of potassium persulfate solution and ammonium persulfate solution.

9. A process for processing hydroxymethylated polyacrylamide according to claim 1, characterized in that: The mass fraction of the initiator solution in step 4 is 2-3%.

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