A polyacrylamide polymer and a method for preparing the same

Abstract

The present application relates to the technical field of high molecular compound preparation, in particular to a kind of polyacrylamide polymer and its preparation method, the preparation method provided by the present application, process flow is simple, in the preparation process, by adding surfactant to the system before azeotrope, make the boiling state can continue to carry out, greatly shorten the azeotrope time, reduce energy consumption while avoiding the particle adhesion caused by long time high temperature azeotrope, simultaneously, the addition of surfactant in the preparation process can speed up the dissolution rate of polyacrylamide solid product, in addition, in the azeotrope process with the help of condensation reflux and the action of water segregator make part of oil phase reflux, particles are not easy to stick together, simultaneously make oil-water separation, it is convenient to recycle oil phase;The polyacrylamide polymer provided by the present application is fast-dissolving granular or powdery, not easy to stick together, fast-dissolving, and good application effect.

Description

Technical Field

[0001] This invention relates to the field of polymer preparation technology, and in particular to a polyacrylamide polymer and its preparation method. Background Technology

[0002] Polyacrylamide, due to its strong water absorption and retention capabilities, is the most consumed and widely used water-soluble polymer, and is extensively applied in construction, oil extraction, water treatment, papermaking, textiles, medicine, and agriculture. The synthesis methods of polyacrylamide generally include aqueous solution polymerization and reverse suspension polymerization. Different polymerization methods produce polyacrylamides with significant differences in product morphology, dissolution rate, and molecular weight.

[0003] The reverse suspension polymerization method involves the stable dispersion of water-soluble monomers in an organic solvent with the help of a suspending dispersant and stirring. The polymerization is then initiated by an initiator to produce granular or powdered solid products. High molecular weight, fast-dissolving powdered anionic polyacrylamide can be prepared by reverse suspension polymerization, alkali hydrolysis, and azeotropic dehydration.

[0004] Since the preparation of anionic polyacrylamide by reverse suspension polymerization requires a large amount of oil phase as a solvent, and the target product is solid particles, the separation and recovery of the solvent becomes crucial. Patent application CN 109021154A discloses a two-step method for preparing fast-dissolving anionic high molecular weight polyacrylamide. This method involves adding the oil phase and stabilizer to a reactor, followed by the addition of a high-concentration monomer aqueous solution, initiator, and hydrolysant. Under stirring conditions, an oil-in-water reaction system is formed. After deoxygenation and heating, an alcohol-water mixture is added dropwise to precipitate the particles, and finally, azeotropic dehydration yields the solid product.

[0005] This polymerization method involves adding an alcohol-water mixture before azeotrope, which prolongs the azeotropic dehydration process. Furthermore, the vapor after azeotrope condensation and reflux cannot be separated, resulting in a waste of organic solvents, increased energy consumption, and environmental pollution.

[0006] Therefore, this application aims to provide a polyacrylamide polymer and its preparation method, which enables rapid dehydration in the azeotropic process of preparing anionic polyacrylamide via reverse-phase suspension, so as to better solve the above-mentioned technical problems. Summary of the Invention

[0007] To address the aforementioned problems, this invention provides a polyacrylamide polymer and its preparation method, which enables rapid dehydration during the azeotropic preparation of anionic polyacrylamide via reverse-phase suspension, reduces particle agglomeration during the azeotropic process, and significantly shortens the azeotropic time, thereby reducing energy consumption.

[0008] The technical solution adopted in this invention is:

[0009] A method for preparing a polyacrylamide polymer includes the following preparation steps:

[0010] S1. Add the dispersant to the hydrocarbon solvent and stir to dissolve the dispersant to obtain the oil phase;

[0011] S2. Prepare a solution of acrylamide monomer with a concentration of 20% to 50%, then add chain transfer agent, chelating agent and water-soluble initiator, stir to dissolve, and obtain an aqueous phase;

[0012] S3. Under stirring conditions, the aqueous phase obtained in step S2 is slowly added to the oil phase in step S1 to form a reverse-phase suspension system;

[0013] S4. Nitrogen gas is introduced into the reverse suspension system to remove oxygen. Then the system is heated to about 30°C. After reacting for a period of time, the water bath temperature is adjusted to about 40°C and kept at that temperature for about 1 hour. Then the system temperature is adjusted to about 50°C and alkali is added to the reaction system to carry out the hydrolysis reaction.

[0014] S5. Add surfactant to the mixture after reaction in step S4, raise the system temperature to the point where the suspension begins to boil, and use the reflux and water separator to reflux part of the oil phase to separate oil and water, making it easier to recover the oil phase. Continue azeotropically until the system is dry, then wash with ethanol and dry to obtain polyacrylamide polymer.

[0015] Further, in step S1, a surfactant with an HLB value of 3 to 8 is used as a dispersant, preferably Span60 and / or Span80, and its content accounts for 3% to 4% of the total mass of the system.

[0016] Furthermore, in step S1, the hydrocarbon solvent is selected from any of cyclopentane, n-hexane, cyclohexane, n-heptane, and n-octane.

[0017] Further, in step S2, the chain transfer agent is selected from any of sodium formate, sodium phosphite, and dodecyl mercaptan, preferably sodium formate, and its addition amount accounts for 0.006% to 0.01% of the monomer content, preferably 0.008%.

[0018] The chelating agent is selected from any of ethylenediaminetetraacetic acid (EDTA), disodium EDTA, and tetrasodium EDTA, preferably disodium EDTA, and its addition amount accounts for 0.03% to 0.04% of the monomer content, preferably 0.035%.

[0019] The water-soluble initiator is a redox initiator and / or an azo initiator.

[0020] Furthermore, in step S2, the redox initiator includes an oxidant and a reducing agent;

[0021] The oxidant is ammonium persulfate or potassium persulfate, and the amount added accounts for 0.2% to 0.4% of the monomer content, preferably 0.3%.

[0022] The reducing agent is selected from any of anhydrous sodium sulfite, anhydrous sodium bisulfite and dimethylaminoethyl methacrylate, preferably dimethylaminoethyl methacrylate (DMA) and another reducing agent are used in a 1:1 ratio, and the amount added accounts for 0.3% to 0.5% of the monomer content, preferably 0.4%.

[0023] Further, in step S3, the stirring speed is 250 r / min to 400 r / min, preferably 300 r / min to 350 r / min; the oil-water ratio in the formed reverse-phase suspension system is 1.5:1 to 2.5:1, preferably 2:1.

[0024] Furthermore, in step S4, nitrogen gas is introduced for 30 to 60 minutes; the system is heated to about 30°C and reacted for 1 to 2 hours, preferably 1.5 hours.

[0025] Further, in step S4, the added alkali is sodium hydroxide and / or sodium carbonate, and the amount added accounts for 10% to 20% of the monomer content, preferably 14% to 16%; the hydrolysis time is 30 to 90 minutes, preferably 60 minutes.

[0026] Further, in step S4, the surfactant is selected from any of sodium dodecyl sulfate, sodium dodecyl sulfonate and fatty alcohol polyoxyethylene ether, preferably sodium dodecyl sulfate, and its addition amount accounts for 0.5% to 1.5% of the mass of the mixture, preferably 1%.

[0027] Based on the same inventive concept, this application also provides a polyacrylamide polymer prepared by the above-described preparation method, wherein the polyacrylamide polymer is in granular or powder form.

[0028] The beneficial effects of this invention are as follows:

[0029] 1. The preparation method provided by the present invention has a simple process flow. During the preparation process, by adding a surfactant to the azeotropic forward system, the boiling state can be sustained, which greatly shortens the azeotropic time, reduces energy consumption, and avoids particle adhesion caused by prolonged high-temperature azeotropy. At the same time, the addition of surfactant during the preparation process can accelerate the dissolution rate of polyacrylamide solid product. In addition, during the azeotropic process, the condensation reflux and water separator help to reflux part of the oil phase, making it less likely for particles to stick together and clump together. At the same time, it enables oil-water separation and facilitates the recovery of the oil phase.

[0030] 2. The polyacrylamide polymer provided by this invention is a fast-dissolving granular or powdery form that is not prone to sticking or clumping and has good application effects. Attached Figure Description

[0031] Figure 1 This is a flowchart illustrating the preparation process in an embodiment of the present invention. Detailed Implementation

[0032] To facilitate understanding of the present invention, it will be described more fully below through embodiments, and preferred embodiments are given below. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Any other implementation schemes obtained by modifying or equivalently substituting the technical solutions of the present invention without inventive step are all within the protection scope of the present invention.

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0034] The numerical values ​​disclosed in the embodiments of this invention are approximate values, not definitive values. Where error or experimental conditions permit, all values ​​within the error range may be included, and the specific numerical values ​​disclosed in the embodiments of this invention are not limited to those specified in the embodiments.

[0035] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0036] Example 1:

[0037] Add 386g of cyclohexane to a 1L four-necked flask, add 20g of Span 80, and heat until dissolved. Add 77g of acrylamide, 0.006g of sodium formate, 0.029g of ethylenediaminetetraacetic acid, and 0.19g of potassium persulfate to 116g of pure water and dissolve. Start stirring at 325 rpm and slowly add the aqueous solution to the four-necked flask. Set the water bath temperature to 30℃ and purge with nitrogen for 30 min. Then add a reducing agent dropwise: 0.04g / ml DMA and sodium bisulfite, totaling 2ml, over 60 min until the system stops heating. Adjust the water bath temperature to 40℃ and maintain the reaction for 2 h. Raise the water bath temperature to 50℃ and add 7.7g of sodium carbonate to the system to initiate a hydrolysis reaction for 1 h. Add 6g of sodium dodecyl sulfate to the system, heat the water bath to 70℃ to bring the system to a boil, and after the liquid in the system has evaporated to dryness, wash the solid particles with a small amount of ethanol, filter, and dry the solid particles to obtain a white granular product with an average particle size of 350μm and a dissolution time of 10min.

[0038] Example 2:

[0039] Add 386g of cyclohexane to a 1L four-necked flask, add 18g of Span 60, and heat until dissolved. Dissolve 77g of acrylamide, 0.006g of sodium formate, 0.029g of ethylenediaminetetraacetic acid (EDTA), and 0.19g of potassium persulfate in 116g of pure water. Start stirring at 250 rpm and slowly add the aqueous solution to the four-necked flask. Set the water bath temperature to 30°C and purge with nitrogen for 30 minutes. Then, add a reducing agent (0.04g / ml DMA and sodium bisulfite), totaling 2ml, over 60 minutes. Continue adding the reducing agent until the system stops heating, then adjust the water bath temperature to 40°C and maintain the reaction for 2 hours. Increase the water bath temperature to 50°C and add 7.7g of sodium carbonate to the system to initiate a hydrolysis reaction for 1 hour. Add 4.5g of sodium dodecyl sulfate to the system, heat the water bath to 70℃ to bring the system to a boil, and after the liquid in the system has evaporated to dryness, wash the solid particles with a small amount of ethanol, filter, and dry the solid particles to obtain a white granular product with an average particle size of 600μm and a dissolution time of 20min.

[0040] Example 3:

[0041] Add 386g of n-heptane to a 1L four-necked flask, add 20g of Span 80, and heat until dissolved. Dissolve 77g of acrylamide, 0.006g of sodium formate, 0.029g of ethylenediaminetetraacetic acid (EDTA), and 0.19g of potassium persulfate in 116g of pure water. Start stirring at 325 rpm and slowly add the aqueous solution to the four-necked flask. Set the water bath temperature to 30°C and purge with nitrogen for 30 minutes. Then, add a reducing agent (0.04g / ml DMA and sodium bisulfite), totaling 2ml, over 60 minutes. Continue adding the reducing agent until the system stops heating, then adjust the water bath temperature to 40°C and maintain the reaction for 2 hours. Increase the water bath temperature to 50°C and add 7.7g of sodium carbonate to the system to initiate a hydrolysis reaction for 1 hour. Add 6g of sodium dodecyl sulfonate to the system, heat the water bath to 80℃ to bring the system to a boil, and after the liquid in the system has evaporated to dryness, wash the solid particles with a small amount of ethanol, filter, and dry the solid particles to obtain a white granular product with an average particle size of 450μm and a dissolution time of 10min.

[0042] Comparative Example 1:

[0043] Add 386g of cyclohexane to a 1L four-necked flask, add 20g of Span 80, and heat until dissolved. Dissolve 77g of acrylamide, 0.006g of sodium formate, 0.029g of ethylenediaminetetraacetic acid (EDTA), and 0.19g of potassium persulfate in 116g of pure water. Start stirring at 325 rpm and slowly add the aqueous solution to the four-necked flask. Set the water bath temperature to 30°C and purge with nitrogen for 30 minutes. Then, add a reducing agent (0.04g / ml DMA and sodium bisulfite), a total of 2ml, over 60 minutes. Continue adding the reducing agent until the system stops heating, then adjust the water bath temperature to 40°C and maintain the reaction for 2 hours. Increase the water bath temperature to 50°C and add 7.7g of sodium carbonate to the system to initiate a hydrolysis reaction for 1 hour. The water bath was heated to 70°C to bring the system to a boil. After the liquid in the system was evaporated to dryness, the solid particles were washed with a small amount of ethanol, filtered, and then dried to obtain a white granular product with an average particle size of 700 μm and a dissolution time of 30 min.

[0044] Comparative Example 2:

[0045] Add 386g of cyclohexane to a 1L four-necked flask, add 20g of Span 80, and heat until dissolved. Dissolve 77g of acrylamide, 0.006g of sodium formate, 0.029g of ethylenediaminetetraacetic acid (EDTA), and 0.19g of potassium persulfate in 116g of pure water. Start stirring at 325 rpm and slowly add the aqueous solution to the four-necked flask. Set the water bath temperature to 30°C and purge with nitrogen for 30 minutes. Then, add a reducing agent (0.04g / ml DMA and sodium bisulfite), a total of 2ml, over 60 minutes. Continue adding the reducing agent until the system stops heating, then adjust the water bath temperature to 40°C and maintain the reaction for 2 hours. Increase the water bath temperature to 50°C and add 7.7g of sodium carbonate to the system to initiate a hydrolysis reaction for 1 hour. Add 15g of Tween 80 (TW80) to the system, heat the water bath to 70℃ to bring the system to a boil, and after the liquid in the system evaporates to dryness, wash the solid particles with a small amount of ethanol, filter, and dry the solid particles to obtain a white granular product with an average particle size of 650μm and a dissolution time of 20min.

[0046] The table below shows the amount of surfactant used and the time consumed in the azeotropic dehydration process in Examples 1-3 and Comparative Examples 1-2:

[0047] Examples / Comparative Examples Surfactant addition amount Time from the start of boiling to dryness Example 1 6g (Sodium dodecyl sulfate) 40min Example 2 4.5g (Sodium dodecyl sulfate) 50min Example 3 6g (Sodium dodecyl sulfonate) 50min Comparative Example 1 0 300min Comparative Example 2 15g (TW80) 300min

[0048] As can be seen from the above embodiments, comparative examples, and statistics on the time consumption of the azeotropic dehydration process, the preparation method provided in this application produces a polyacrylamide polymer that enables rapid dehydration in the azeotropic process of preparing anionic polyacrylamide via reverse-phase suspension. This reduces particle adhesion during the azeotropic process, results in a fast dissolution rate, and achieves good application effects. At the same time, it greatly shortens the azeotropic time and reduces energy consumption.

[0049] Specifically, the preparation method provided in this application includes the following steps during the preparation process:

[0050] (1) By adding surfactants to the azeotropic forward system, the boiling state can be sustained, which greatly shortens the azeotropic time, reduces energy consumption, and avoids particle adhesion caused by long-term high-temperature azeotropy.

[0051] (2) The addition of surfactant in this invention can accelerate the dissolution rate of solid polyacrylamide products;

[0052] (3) In the azeotropic process, the present invention uses the condensation reflux and water separator to make part of the oil phase reflux, so that the particles are not easy to stick together and clump together, and at the same time, the oil and water are separated, making it easy to recover the oil phase.

[0053] In summary, the preparation method provided in this application is simple in preparation steps and easy to operate. During the preparation process, the azeotropic time is shortened by reasonable selection and addition of components, which effectively reduces energy consumption and improves the dissolution rate of the anionic polyacrylamide solid product, thus better meeting application requirements.

[0054] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A method for preparing a polyacrylamide polymer, characterized in that, The preparation steps include the following: S1. Add the dispersant to the hydrocarbon solvent and stir to dissolve the dispersant to obtain the oil phase; S2. Prepare a solution of acrylamide monomer with a concentration of 20% to 50%, then add chain transfer agent, chelating agent and water-soluble initiator, stir to dissolve, and obtain an aqueous phase; S3. Under stirring conditions, the aqueous phase obtained in step S2 is slowly added to the oil phase in step S1 to form a reverse-phase suspension system; S4. Nitrogen gas is introduced into the reverse suspension system to remove oxygen. Then the system is heated to 30°C. After reacting for a period of time, the water bath temperature is adjusted to 40°C and kept at that temperature for 1 or 2 hours. Then the system temperature is adjusted to 50°C and alkali is added to the reaction system to carry out the hydrolysis reaction. S5. Add surfactant to the mixture after reaction in step S4, raise the system temperature to the point where the suspension begins to boil, and use the reflux and water separator to reflux part of the oil phase to separate oil and water, making it easier to recover the oil phase. Continue azeotropically until the system is evaporated to dryness, then wash with ethanol and dry to obtain polyacrylamide polymer. The surfactant added to the mixture after the reaction in step S4 is selected from sodium dodecyl sulfate and / or sodium dodecyl sulfonate, and its addition amount accounts for 0.5% to 1.5% of the mass of the mixture.

2. The method for preparing the polyacrylamide polymer according to claim 1, characterized in that, In step S1, a surfactant with an HLB value of 3 to 8 is used as a dispersant, and its content accounts for 3% to 4% of the total mass of the system.

3. The method for preparing the polyacrylamide polymer according to claim 1, characterized in that, In step S1, the hydrocarbon solvent is selected from any of cyclopentane, n-hexane, cyclohexane, n-heptane, and n-octane.

4. The method for preparing the polyacrylamide polymer according to claim 1, characterized in that, In step S2, the chain transfer agent is selected from any of sodium formate, sodium phosphite, and dodecyl mercaptan, and its addition amount accounts for 0.006% to 0.01% of the monomer content; The chelating agent is selected from any of ethylenediaminetetraacetic acid (EDTA), disodium EDTA, and tetrasodium EDTA, and its addition amount accounts for 0.03% to 0.04% of the monomer content. The water-soluble initiator is a redox initiator.

5. The method for preparing the polyacrylamide polymer according to claim 4, characterized in that, In step S2, the redox initiator includes an oxidant and a reducing agent; The oxidant is ammonium persulfate or potassium persulfate, and the amount added accounts for 0.2% to 0.4% of the monomer content. The reducing agent is selected from at least one of anhydrous sodium sulfite and anhydrous sodium bisulfite, and the amount added accounts for 0.3% to 0.5% of the monomer content.

6. The method for preparing the polyacrylamide polymer according to claim 1, characterized in that, In step S3, the stirring speed is 250 r / min to 400 r / min; the oil-water mass ratio in the formed reverse-phase suspension system is 1.5:1 to 2.5:

1.

7. The method for preparing the polyacrylamide polymer according to claim 1, characterized in that, In step S4, nitrogen gas is introduced for 30 to 60 minutes; the system is heated to 30°C and reacted for 1 to 2 hours.

8. The method for preparing the polyacrylamide polymer according to claim 1, characterized in that, In step S4, the added alkali is sodium hydroxide and / or sodium carbonate, and the amount added accounts for 10% to 20% of the monomer content; the hydrolysis time is 30 to 90 minutes.

9. The polyacrylamide polymer prepared by the method according to any one of claims 1 to 8, characterized in that, The polyacrylamide polymer is in granular form.

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