A preparation method of heat-resistant and salt-resistant polyacrylamide

Abstract

The present application relates to a method for preparing a heat-resistant and salt-resistant polyacrylamide, comprising the following steps: mixing a monomer with deionized water to obtain a monomer solution, adjusting the pH value, adding a thickener to the monomer solution after adjusting the pH value, shearing and emulsifying, obtaining a prefabricated polyacrylamide emulsion system, stirring the polyacrylamide emulsion system, heating to 35-45°C while stirring, adding an initiator to the system, keeping the stirring condition to react, cooling the system to 20-30°C after the reaction, adding a phase transfer agent, continuing to stir, and obtaining a polyacrylamide emulsion; the monomers include acrylamide, 2-acrylamido-2-methyl-1-propane sulfonic acid and sodium allyl sulfonate. The present application has the effect of improving the heat-resistant and salt-resistant properties of polyacrylamide.

Description

Technical Field

[0001] The present application relates to the field of polyacrylamide preparation, and in particular to a method for preparing temperature-resistant and salt-resistant polyacrylamide. Background Art

[0002] Polyacrylamide (PAM) is a linear polymer that is a hard glassy solid at room temperature. Its products include glue, latex, white powder, translucent beads and flakes. Polyacrylamide is a general term for polymers obtained by copolymerization of acrylamide homopolymer or other monomers. It is one of the most widely used varieties of water-soluble polymers. Since the structural unit of polyacrylamide contains amide groups and is easy to form hydrogen bonds, it has good water solubility and high chemical activity. It is easy to obtain a variety of modified products with branched or network structures through grafting or cross-linking. It has a wide range of applications in industries such as oil extraction, water treatment, textiles, papermaking, mineral processing, medicine, and agriculture.

[0003] In oil extraction technology, the mineral environment is generally a saline environment, and the performance requirements for polyacrylamide have also been improved. In the existing technology, polyacrylamide has the defect of poor salt resistance, which will reduce the viscosity of polyacrylamide and affect the oil recovery effect, so it needs to be improved. Summary of the invention

[0004] In order to improve the salt resistance of polyacrylamide, the present application provides a method for preparing temperature-resistant and salt-resistant polyacrylamide.

[0005] The present application provides a method for preparing a heat-resistant and salt-resistant polyacrylamide using the following technical solution:

[0006] A method for preparing a heat-resistant and salt-resistant polyacrylamide comprises the following steps:

[0007] The monomer is mixed with deionized water to obtain a monomer solution, and after adjusting the pH value, a thickener is added to the monomer solution after adjusting the pH value, and shearing and emulsification are performed to obtain a prefabricated polyacrylamide emulsion system, and the polyacrylamide emulsion system is stirred, and the temperature is raised to 35-45° C. while stirring, and an initiator is added to the system, and the stirring condition is maintained to react, and after the reaction, the system is cooled to 20-30° C., a phase transfer agent is added, and stirring is continued to obtain a polyacrylamide emulsion;

[0008] The monomers include acrylamide, 2-acrylamido-2-methyl-1-propane sulfonic acid and sodium allyl sulfonate.

[0009] By adopting the above technical scheme, sodium styrene sulfonate is introduced into acrylamide and 2-acrylamido-2-methyl-1-propane sulfonic acid to prepare anionic polyacrylamide emulsion. Sodium styrene sulfonate is a hydrophilic anionic monomer that can fully participate in polymerization reactions in aqueous solutions. At the same time, sodium styrene sulfonate has a sulfonic acid group that can play a good salt resistance role, and its benzene ring structure can improve the rigidity of the polymer chain, thereby improving the temperature resistance of polyacrylamide.

[0010] Preferably, the mass ratio of acrylamide to 2-acrylamido-2-methyl-1-propane sulfonic acid is (4.3-4.5):1.

[0011] By adopting the above technical solution, preferably the mass ratio of acrylamide to 2-acrylamido-2-methyl-1-propane sulfonic acid is within the above range, the stability of the prepared polyacrylamide can be further improved.

[0012] Preferably, the sodium allyl sulfonate accounts for 1-5% of the total weight of the monomers.

[0013] By adopting the above technical solution and controlling the mass proportion of sodium allyl sulfonate in the monomer, the stability of the system can be further improved.

[0014] Preferably, the initiator comprises potassium persulfate and sodium bisulfite.

[0015] By adopting the above technical solution, the initiator includes an oxidizing agent potassium persulfate and a reducing agent sodium bisulfite, and an oxidation-reduction initiation system is selected. Compared with a single peroxide initiation, the addition of a reducing agent can increase the initiation rate at a lower temperature, and is conducive to the stability of the reaction and the increase of the polymer molecular weight, thereby improving the conversion rate. At the same time, controlling the mass ratio between potassium persulfate and sodium bisulfite in the initiator within the above range can further improve the stability of the monomer polymerization.

[0016] Preferably, the initiator accounts for 0.05-0.3% of the monomer mass.

[0017] By adopting the above technical solution, the mass ratio of the initiator to the monomer is preferably within the above range, which can further improve the stability of the monomer reaction.

[0018] Preferably, the pH value of the monomer solution is between 7.5 and 8.5.

[0019] By adopting the above technical solution, the pH value of the monomer solution is controlled within the above range, so that the viscosity of the polymer is excellent, thereby further improving the quality of the prepared product.

[0020] Preferably, the thickener comprises isoamyl caprylate, a dispersant and an emulsifier.

[0021] By adopting the above technical scheme, isoamyl octanoate can further improve the stability of polyacrylamide emulsion, and can further improve the dispersion uniformity between various components in the emulsion system. At the same time, isoamyl octanoate can be degraded, which further improves the green and environmental protection of the preparation of polyacrylamide; after adding a dispersant to the system, various components in the system can be evenly dispersed in the system, thereby improving the overall stability of the prepared emulsion.

[0022] Preferably, the thickener is prepared by the following method:

[0023] Tween-80 and Span-80 are mixed to obtain an emulsifier, and white oil, isoamyl octanoate, azobisisobutyronitrile and the emulsifier are mixed and stirred to obtain a thickener.

[0024] Preferably, the mass ratio between the isopentyl octanoate and the emulsifier is (4.9-5.3):1.

[0025] By adopting the above technical solution, preferably the mass ratio between isoamyl octanoate and the emulsifier is within the above range, which can further improve the overall stability of the system.

[0026] Preferably, the dispersant includes any one of white oil, octadecenol and castor oil.

[0027] In summary, the present application includes at least one of the following beneficial technical effects:

[0028] 1. Using acrylamide, 2-acrylamido-2-methyl-1-propane sulfonic acid and sodium styrene sulfonate as monomers, a silver ion polyacrylamide emulsion is prepared. Sodium styrene sulfonate has a sulfonic acid group, which can play a good salt resistance role. At the same time, its benzene ring structure can improve the rigidity of the polymer chain, so as to improve the overall temperature resistance of the prepared polyacrylamide system, thereby improving the product stability and product quality;

[0029] 2. The initiator uses an oxidation-reduction initiator system, which is prepared by compounding potassium persulfate and sodium bisulfite. After adding a reducing agent, the initiation rate of the system can be increased at a lower temperature, and the prepared monomer polymer can be made more stable, thereby improving product quality;

[0030] 3. A thickener is added to adjust the viscosity of the system. The thickener is prepared from isopentyl octanoate, a dispersant and an emulsifier. Isopentyl octanoate can be compounded with the dispersant to improve the dispersion effect of each component of the system, thereby improving product quality. DETAILED DESCRIPTION

[0031] The present application is further described in detail below with reference to the embodiments:

[0032] Raw material description: Phase inversion agent is OP-10 (CAS No.: 9041-29-6)

[0033] Example 1

[0034] Prepare the thickener:

[0035] 75 g of Tween-80 (CAS No.: 9005-65-6) and 75 g of Span-80 (CAS No.: 1338-43-8) were mixed to obtain an emulsifier, and 615 g of white oil (CAS No.: 8042-47-5), 735 g of isopentyl octanoate (CAS No.: 2035-99-6), 6 g of azobisisobutyronitrile (CAS No.: 78-67-1) and 150 g of the prepared emulsifier were mixed and stirred to obtain a thickener.

[0036] Preparation of initiator:

[0037] 7.92 g of potassium persulfate and 2.08 g of sodium bisulfite were mixed to obtain an initiator.

[0038] Preparation of monomers:

[0039] A monomer was obtained by mixing 2008.02 g of acrylamide (CAS No.: 79-06-1), 466.98 g of 2-acrylamido-2-methyl-1-propanesulfonic acid (CAS No.: 15214-89-8) and 25 g of sodium allyl sulfonate (CAS No.: 2495-39-8).

[0040] Preparation of polyacrylamide emulsion:

[0041] 2000 g of monomer was mixed with 1500 g of deionized water and stirred until the monomer was fully dissolved to obtain a monomer solution. Sodium hydroxide was used to adjust the pH value of the monomer solution to 7.5. 1200 g of the thickener prepared above was added to the monomer solution after adjusting the pH value. The solution was sheared and emulsified at a speed of 6000 rpm for 10 min to obtain a prefabricated polyacrylamide emulsion system. The polyacrylamide emulsion system prepared above was stirred at a speed of 300 rpm, and nitrogen was introduced at the same time. Stirring was maintained for 30 min under nitrogen protection conditions, and the temperature was raised to 40° C. while stirring. 1 g of the initiator prepared above was added to the system. The nitrogen protection and stirring conditions were maintained for 8 h. After the reaction, the system was cooled to 25° C., a phase inversion agent was added, and stirring was continued for 10 min to obtain a polyacrylamide emulsion.

[0042] Example 2

[0043] Prepare the thickener:

[0044] 75 g of Tween-80 and 75 g of Span-80 were mixed to obtain an emulsifier, and 555 g of white oil, 795 g of isoamyl octanoate, 6 g of azobisisobutyronitrile and 150 g of the prepared emulsifier were mixed and stirred to obtain a thickener.

[0045] Preparation of initiator:

[0046] 8.08 g of potassium persulfate and 1.92 g of sodium bisulfite were mixed to obtain an initiator.

[0047] Preparation of monomers:

[0048] A monomer was obtained by mixing 1943.18 g of acrylamide, 431.82 g of 2-acrylamido-2-methyl-1-propanesulfonic acid and 125 g of sodium allyl sulfonate.

[0049] Preparation of polyacrylamide:

[0050] 2400g of monomer was mixed with 1600g of deionized water and stirred until the monomer was fully dissolved to obtain a monomer solution. Sodium hydroxide was used to adjust the pH value of the monomer solution to 8.5. 1300g of the thickener prepared above was added to the monomer solution after adjusting the pH value. The solution was sheared and emulsified at a speed of 6000rpm for 10min to obtain a prefabricated polyacrylamide emulsion system. The polyacrylamide emulsion system prepared above was stirred at a speed of 300rpm, and nitrogen was introduced at the same time. Stirring was maintained for 30min under nitrogen protection, and the temperature was raised to 40°C while stirring. 7.2g of the initiator prepared above was added to the system. The nitrogen protection and stirring conditions were maintained for 8h. After the reaction, the system was cooled to 25°C, a phase inversion agent was added, and stirring was continued for 10min to obtain a polyacrylamide emulsion.

[0051] Example 3

[0052] Prepare the thickener:

[0053] 75 g of Tween-80 and 75 g of Span-80 were mixed to obtain an emulsifier, and 585 g of white oil, 765 g of isoamyl octanoate, 6 g of azobisisobutyronitrile and 150 g of the prepared emulsifier were mixed and stirred to obtain a thickener.

[0054] Preparation of initiator:

[0055] 8 g of potassium persulfate and 2 g of sodium bisulfite were mixed to obtain an initiator.

[0056] Preparation of monomers:

[0057] A monomer was obtained by mixing 1975.93 g of acrylamide, 449.07 g of 2-acrylamido-2-methyl-1-propanesulfonic acid, and 75 g of sodium allylsulfonate.

[0058] Preparation of polyacrylamide emulsion:

[0059] 2200g of monomer was mixed with 1550g of deionized water and stirred until the monomer was fully dissolved to obtain a monomer solution. Sodium hydroxide was used to adjust the pH value of the monomer solution to 8. 1250g of the thickener prepared above was added to the monomer solution after adjusting the pH value. The mixture was sheared and emulsified at a speed of 6000rpm for 10min to obtain a prefabricated polyacrylamide emulsion system. The polyacrylamide emulsion system prepared above was stirred at a speed of 300rpm, and nitrogen was introduced at the same time. Stirring was maintained for 30min under nitrogen protection, and the temperature was raised to 40°C while stirring. 3.3g of the initiator prepared above was added to the system. The reaction was maintained under nitrogen protection and stirring conditions for 8h. After the reaction, the system was cooled to 25°C, a phase inversion agent was added, and stirring was continued for 10min to obtain a polyacrylamide emulsion.

[0060] Example 4

[0061] Example 4 is based on Example 3. The difference between Example 4 and Example 3 is that in Example 4, when preparing the compound thickener, 675 g of dispersant and 675 g of isoamyl octanoate are used.

[0062] Example 5

[0063] Example 5 is based on Example 3. In Example 5, 855 g of isoamyl octanoate and 495 g of dispersant are added.

[0064] Example 6

[0065] Example 6 is based on Example 3. The difference between Example 6 and Example 3 is that the amount of initiator added in Example 6 is 0.5 g.

[0066] Example 7

[0067] Example 7 is based on Example 3. The difference between Example 7 and Example 3 is that the amount of initiator added in Example 7 is 10 g.

[0068] Example 8

[0069] Example 8 is based on Example 3. The difference between Example 8 and Example 3 is that the initiator in Example 8 is only potassium persulfate.

[0070] Example 9

[0071] Example 9 is based on Example 3. The difference between Example 9 and Example 3 is that in Example 9, when preparing the monomer, 1930.1 g of acrylamide and 494.9 g of 2-acrylamide-2-methyl-1-propane sulfonic acid are added.

[0072] Example 10

[0073] Example 10 is based on Example 3. The difference between Example 10 and Example 3 is that in Example 10, when preparing the monomer, 2013.98 g of acrylamide and 411.02 g of 2-acrylamide-2-methyl-1-propane sulfonic acid are added.

[0074] Embodiment 11

[0075] Example 11 is based on Example 3. The difference between Example 11 and Example 3 is that in Example 11, when preparing the monomer, 12.5 g of sodium allyl sulfonate, 2026.85 g of acrylamide, and 460.65 g of 2-acrylamido-2-methyl-1-propane sulfonic acid are added.

[0076] Example 12

[0077] Example 12 is based on Example 3. The difference between Example 12 and Example 3 is that in Example 12, when preparing the monomer, 250 g of sodium allyl sulfonate, 1833.33 g of acrylamide, and 416.67 g of 2-acrylamide-2-methyl-1-propane sulfonic acid are added.

[0078] Example 13

[0079] Example 13 is based on Example 3. The difference between Example 13 and Example 3 is that in Example 13, the pH value is adjusted to 6 when preparing the monomer solution.

[0080] Embodiment 14

[0081] Example 14 is based on Example 3. The difference between Example 14 and Example 3 is that in Example 14, the pH value is adjusted to 10 when preparing the monomer solution.

[0082] Comparative Example 1

[0083] Comparative Example 1 is based on Example 3. The difference between Comparative Example 1 and Example 3 is that in Comparative Example 1, no sodium allyl sulfonate is added when preparing the monomer.

[0084] Performance testing

[0085] The acrylic emulsions of Examples 1-13 and Comparative Example 1 were sampled and subjected to the following performance tests:

[0086] (1) Temperature resistance performance test

[0087] The viscosity of the prepared polyacrylamide was tested using a rheometer at 90°C and 170s-1. Each sample was tested three times, and the average value was taken and the test results were filled in Table 1.

[0088] (2) Salt resistance test

[0089] Prepare a 5000 mg / L sodium chloride aqueous solution, add the sample into the prepared sodium chloride aqueous solution of different concentrations, keep it at 40°C for 12 hours, test the viscosity of the sample, test each sample three times, take the average value, and fill in the test results in Table 1.

[0090] Table 1 Performance test results of polyacrylamide emulsion of Examples 1-13 and Comparative Example 1

[0091]

[0092]

[0093] Data analysis

[0094] Combined with Table 1, it can be seen that in Examples 1-3, at 25°C, the apparent viscosity of the samples is 95 mPa·s, indicating that the polyacrylamide emulsion product prepared in the present application has good quality; the apparent viscosity of Examples 1-3 at 90°C is 65 mPa·s or above, indicating that the polyacrylamide emulsion prepared in the present application has good temperature resistance; the apparent viscosity of Examples 1-3 after aging in 5000 mg / L sodium chloride solution is 55 mPa·s or above, indicating that the polyacrylamide emulsion prepared in the present application has good salt resistance.

[0095] In Example 4 and Example 5, when preparing the compound thickener, the mass ratio between isoamyl caprylate and the emulsifier is not within the range specified in the present application. When the content of isoamyl caprylate is too little, it is difficult to further improve the dispersion effect of each substance in the system, and the promoting effect on the stability of the polyacrylamide emulsion is small; when the content of isoamyl caprylate is too much, the polymerization reaction equilibrium of the monomer decreases, the stability of the emulsion decreases, and thus affects the product quality. Therefore, the various performances of Example 4 and Example 5 are all reduced.

[0096] The initiator contents in Examples 6 and 7 are not within the range defined in the present application. When the initiator content is too much, the probability of chain transfer and chain termination increases during monomer polymerization, the average molecular weight of the product decreases, and the solubility of the product also decreases, resulting in a decrease in product quality. When the initiator content is too little, the concentration of active free radicals in the system decreases, the conversion rate is difficult to improve, and the quality of the prepared product is affected. Therefore, the various performances of Examples 6 and 7 are reduced.

[0097] In Example 8, only potassium persulfate is used as an initiator. The reaction induction period of a single initiator is too long. At the same time, it is difficult to promote the smooth progress of the reaction and the increase in the molecular weight of the polymer. The initiation rate is also reduced, and the quality of the prepared product is reduced. Therefore, various properties in Example 8 are reduced.

[0098] In Examples 9 and 10, when preparing the monomer, the mass ratio of acrylamide to 2-acrylamide-2-methyl-1-propane sulfonic acid is not within the range defined in the present application. When the content of acrylamide is too low, the excessive 2-acrylamide-2-methyl-1-propane sulfonic acid and the bulky side groups on the molecular chain have an adverse effect on the dispersion of the monomer and the formation of free radicals, and the molecular weight of the product decreases, so the product quality decreases; when the content of acrylamide is too high, the steric hindrance increased by the large side groups of the insufficient 2-acrylamide-2-methyl-1-propane sulfonic acid decreases, and the electrostatic effect generated by its strong polar groups also decreases, and it is difficult for the two to polymerize to form a stretched long molecular chain, so it will also affect the product quality. Therefore, the various properties of Examples 9 and 10 are all reduced.

[0099] In Example 11 and Example 12, when preparing the monomer, the content of the added sodium allyl sulfonate is not within the range specified in the present application. When the content of sodium allyl sulfonate is too little, the effect of improving the heat and salt resistance of the polymer is weak. When the content of sodium allyl sulfonate is too much, the overall stability of the system is affected, resulting in a significant decrease in product quality. Therefore, the various performances of Example 11 and Example 12 are reduced.

[0100] The pH adjustment of the monomer solution in Examples 13 and 14 is not within the range defined in the present application. When the pH value is too low, it is not conducive to the participation of 2-acrylamide-2-methyl-1-propane sulfonic acid and sodium allyl sulfonate in the reaction, and the viscosity of the system is difficult to improve. When the pH value is too high, the rate at which the initiator system decomposes to produce free radicals is inhibited, and it is difficult to promote the reaction, which prolongs the reaction time. At the same time, it accelerates the hydrolysis of acrylamide, and the viscosity of the system is difficult to improve. Therefore, the various performances of Examples 13 and 14 are reduced.

[0101] In Comparative Example 1, no sodium allyl sulfonate is added to the monomer, the content of sulfonate groups in the system decreases, and the content of benzene ring structure decreases, and it is difficult to improve the salt resistance and temperature resistance of the system. Therefore, various properties in Comparative Example 1 are reduced.

[0102] This specific embodiment is only an explanation of the present application, and it is not a limitation of the present application. Through the above description, relevant staff can make various changes and modifications without deviating from the technical idea of ​​the present application. The technical scope of the present application is not limited to the content in the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. A method for preparing a heat-resistant and salt-resistant polyacrylamide, characterized in that: The steps include: The monomer is mixed with deionized water to obtain a monomer solution, and after adjusting the pH value, a thickener is added to the monomer solution after adjusting the pH value, and shearing and emulsification are performed to obtain a prefabricated polyacrylamide emulsion system, and the polyacrylamide emulsion system is stirred, and the temperature is raised to 35-45° C. while stirring, and an initiator is added to the system, and the stirring condition is maintained to react, and after the reaction, the system is cooled to 20-30° C., a phase transfer agent is added, and stirring is continued to obtain a polyacrylamide emulsion; The monomers include acrylamide, 2-acrylamido-2-methyl-1-propane sulfonic acid and sodium allyl sulfonate; The mass ratio of acrylamide to 2-acrylamido-2-methyl-1-propane sulfonic acid is (4.3-4.5):1; The sodium allyl sulfonate accounts for 1-5% of the total mass of the monomer; The pH value of the monomer solution is between 7.5 and 8.

5.

2. The method for preparing a heat-resistant and salt-resistant polyacrylamide according to claim 1, characterized in that: The initiator includes potassium persulfate and sodium bisulfite.

3. The method for preparing a heat-resistant and salt-resistant polyacrylamide according to claim 2, characterized in that: The initiator is 0.05-0.3% of the monomer mass.

4. The method for preparing a heat-resistant and salt-resistant polyacrylamide according to claim 1, characterized in that: The thickener comprises isoamyl octanoate, a dispersant and an emulsifier.

5. The method for preparing a heat-resistant and salt-resistant polyacrylamide according to claim 4, characterized in that: The thickener is prepared by the following method: Tween-80 and Span-80 are mixed to obtain an emulsifier, and white oil, isoamyl octanoate, azobisisobutyronitrile and the emulsifier are mixed and stirred to obtain a thickener.

6. The method for preparing a heat-resistant and salt-resistant polyacrylamide according to claim 4, characterized in that: The mass ratio between the isopentyl octanoate and the emulsifier is (4.9-5.3):

1.

7. The method for preparing a heat-resistant and salt-resistant polyacrylamide according to claim 4, characterized in that: The dispersant includes any one of white oil, octadecenol and castor oil.

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