Cationic thickener and preparation method thereof

Abstract

The present invention provides a cationic thickener and a preparation method thereof. The cationic thickener has a structural formula: #imgabs0#. The preparation method comprises uniformly mixing acrylamide, a cationic monomer A, a cationic double-chain monomer B, a surfactant, a catalyst, and water, dripping an initiator aqueous solution into the mixed system to initiate a reaction, and obtaining the fracturing fluid thickener after the reaction. The fracturing fluid thickener prepared by the present invention has the advantages of good salt resistance, good temperature resistance, and good shear resistance.

Description

Technical Field

[0001] The present invention relates to the field of fracturing fluid thickener preparation, in particular to a cationic thickener and a preparation method thereof. Background Art

[0002] With the continuous exploitation of oil and gas resources, complex reservoirs such as deep wells with high temperature, high mineralization and low permeability have become the main areas of oil field development. Chemical flooding, as one of the main measures to improve the recovery rate during oil and gas extraction, has been widely used in the field of tertiary oil recovery. Among them, polymer flooding has become a widely used tertiary oil recovery technology in my country due to its direct effect, simple construction method and low cost. It has been industrially applied in oil fields such as Daqing, Shengli and Dagang. As the core technology of polymer drive, the research and development of oil displacement agents is very important. Among them, polyacrylamide and xanthan gum oil displacement agents are the two most important types of polymer flooding oil displacement agents. Since polyacrylamide polymers generally have good viscoelasticity and can significantly improve the recovery rate of residual oil, polyacrylamide polymers are more widely used than xanthan gum polymers.

[0003] Conventional polyacrylamide (PAM) molecules experience rapid hydrolysis of amide groups in slightly acidic or alkaline environments. In neutral environments, increasing temperature accelerates the hydrolysis rate. Consequently, conventional PAM exhibits poor temperature and salt tolerance. Consequently, its molecular structure restricts its application to medium-low-temperature, low-salinity reservoirs. Limited by its molecular structure and viscosity-increasing mechanism, the currently commonly used partially hydrolyzed polyacrylamide (HPAM) is a linear polymer. In saline solutions, electrostatic shielding and dehydration by metal cations cause the molecular chains to curl, reducing their size and rapidly decreasing the solution viscosity. Currently, higher requirements are being placed on polymer fracturing fluids for properties such as salt tolerance, temperature and shear resistance, reservoir contamination resistance, and formation compatibility.

[0004] Polyacrylamide, a commonly used thickener in chemical flooding, has attracted widespread attention for its excellent performance and low cost. Currently, the majority of commonly used thickeners in chemical flooding are anionic polyacrylamide, which is widely recognized in the market for its good solubility, high stability, and low cost. However, these thickeners are not suitable for high-temperature, high-salinity oilfields. Summary of the Invention

[0005] In response to the current application bottleneck of high-salt oil fields, the present application provides a new cationic functional thickener, which can achieve good viscosity increasing effect in high-temperature and high-salt environments, and has excellent salt resistance, shear resistance and temperature resistance.

[0006] To this end, the first technical solution provided by the present invention is as follows:

[0007] A cationic thickener, the structural formula of which is shown in Formula 1:

[0008] ;

[0009] Formula 1

[0010] Where: x=1-98000, y=1-6000, z=1-2000;

[0011] R1 is one of (C1-C22) alkyl, (C1-C25) ethoxy, (C1-C25) hydroxyalkyl, (C1-C25) phenyl, and (C1-C25) sulfonic acid;

[0012] R2 is one of (C1-C22) alkyl, (C1-C25) ethoxy, (C1-C25) hydroxyalkyl, (C1-C25) phenyl, and (C1-C25) sulfonic acid.

[0013] The second technical solution provided by the present invention is as follows:

[0014] A method for preparing a cationic thickener comprises the following steps in sequence:

[0015] (1) Weigh acrylamide, cationic monomer A, cationic double-chain monomer B, and surfactant according to a certain mass and dissolve them in a certain mass of deionized water;

[0016] (2) Add the catalyst to the aqueous solution in (1) and dissolve it. Adjust the pH of the solution to neutral with sodium carbonate. Pour the solution into the reactor and introduce nitrogen for a period of time.

[0017] (3) Weigh a certain amount of initiator and add a certain amount of deionized water to dissolve it;

[0018] (4) The air in the reactor in step (2) is removed and the initiator solution in step (3) is added dropwise. At the same time, the system temperature is raised and the reaction is carried out for several hours;

[0019] (5) The white colloidal substance was cut into pieces, washed several times with anhydrous ethanol, and then dried in a vacuum oven.

[0020] The total mass of the raw materials is the total mass of acrylamide, cationic monomer A, cationic double-chain monomer B, surfactant, catalyst, initiator and deionized water.

[0021] Furthermore, in the above-mentioned method for preparing a cationic thickener, the mass of acrylamide accounts for 12.0-22.0% of the total mass of the raw materials;

[0022] Furthermore, in the preparation method of the above-mentioned cationic thickener, the cationic monomer A is at least one of acryloyloxyethyltrimethylammonium chloride, dimethyldiallyl ammonium chloride, diallylamine chloride, diallyl-N-carbonylbutoxymethylammonium chloride, N,N-dimethyl-N-benzyl-acryloyloxyammonium chloride, methacryloyloxyethyltrimethylammonium chloride, diallylethylbenzylammonium chloride, methacrylamidopropyltrimethylammonium chloride, diallylamine, and acrylamidopropyltrimethylammonium chloride, and the mass of the cationic monomer A accounts for 3.0-15.0% of the total mass of the raw materials;

[0023] Furthermore, in the preparation method of the above-mentioned cationic thickener, the cationic double-chain monomer B is homemade in the laboratory and belongs to the diallyl quaternary ammonium salt derivative. It has the appearance of a light yellow oily liquid and its mass accounts for 0.05-3.0% of the total mass of the raw materials;

[0024] The specific preparation method is as follows: the preparation method of the cationic double-chain monomer B comprises the following steps: weighing 1.0 mol of diallylamine, 1.0 mol of potassium carbonate and ethanol, mixing them evenly, stirring for 10-30 minutes, controlling the temperature to 60-80°C, then dropwise adding 2.0-2.5 mol of bromoalkane to the solution, reacting for 6-10 hours after the addition is completed, adjusting the temperature to 40-60°C, reacting for 18-30 hours, cooling to room temperature, filtering, and rotary evaporation to obtain a light yellow associated active substance, which is then set aside for later use.

[0025] Furthermore, in the preparation method of the above-mentioned cationic thickener, the surfactant is at least one of dodecylaminopropionic acid, octadecylamidopropylamine oxide, dodecyldimethylsulfopropyl betaine, hexadecyltrimethylammonium chloride, dodecylethoxysulfobetaine, tetradecylamidopropylhydroxypropylsulfobetaine, octadecyldihydroxyethylamine oxide, sodium lauryl sulfate, dodecyldimethylhydroxypropylsulfobetaine, hexadecyldimethylhydroxypropylphosphate betaine, lauryl alcohol polyoxyethylene ether 2-acrylamido-2-dimethylpropanesulfonic acid, decyldimethylhydroxypropylsulfobetaine, and sodium laurylsulfonate, and the mass of the surfactant accounts for 0.5-3.0% of the total mass of the raw materials;

[0026] Furthermore, in the preparation method of the above-mentioned cationic thickener, the catalyst is at least one of 1,4-butanediol, 1,6-hexanediol, bis-hydroxyethyl (or hydroxypropyl) bisphenol A, ethylene glycol, glycerol, propylene glycol, 1,4-bis(hydroxyethyl) hydroquinone, hydrogenated bisphenol A, 1,4-cyclohexanediol, 1,4-bis(hydroxyethyl) piperazine, pentaerythritol, trimethylolpropane, tetramethylethylenediamine, diethylamine, diethylene glycol, dimethylaminopropionitrile, triethylene glycol, neopentyl glycol, hydrogenated bisphenol A, 1,4-cyclohexanediol, sorbitol, diethylamino anhydrous ethanol, N,N'-methylenebisacrylamide, and sodium formate, and the mass of the catalyst accounts for 0.005-0.1% of the total mass of the raw materials;

[0027] Furthermore, the preparation method of the above-mentioned cationic thickener is characterized in that the initiator is at least one of sodium bisulfite, sodium thiosulfate, dicyclohexyl peroxydicarbonate, ammonium persulfate, azobisisobutyronitrile, azobisisobutylimidazoline hydrochloride, azobisisobutylamidine hydrochloride, potassium persulfate, azobiscyanovaleric acid, azobisisopropylimidazoline, and sodium persulfate, and its mass accounts for 0.001-0.1% of the total mass of the raw materials;

[0028] Furthermore, the preparation method of the above-mentioned cationic thickener is characterized in that the reaction temperature in step (4) is 30-80°C and the reaction time is 2-20h;

[0029] Furthermore, the preparation method of the above-mentioned cationic thickener is characterized in that the product is washed with anhydrous ethanol, and the vacuum drying temperature is 50-100° C. and the drying time is 6-48 hours.

[0030] Compared with the prior art, the technical solution provided by the present invention has the following technical advantages:

[0031] The cationic functional thickener prepared by the present invention can achieve a good thickening effect in a high-temperature and high-salt environment, and has excellent salt resistance, shear resistance and temperature resistance. The thickener structure contains both hydrophilic groups and hydrophobic groups. The hydrophilic groups in the molecules, such as amide groups, form hydrogen bond associations after contact with water, while the hydrophobic groups, due to the hydrophobic effect, aggregate and entangle the thickener molecules with each other. They work together to form a macromolecular network with a spatial network structure in water. In addition, due to the presence of dicationic groups, there is an electrostatic repulsive force between them, and the thickener molecular chain is more stretched, which is conducive to the association between the thickener molecules and improves the salt resistance of the thickener molecules. The hydrogen bonds, van der Waals forces, electrostatic repulsive forces, and hydrophobic associations work together to increase the fluid dynamics volume of the thickener, thereby improving the apparent viscosity and shear resistance of the thickener aqueous solution. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is an infrared spectrum of the structure of thickener molecule Q3 in Example 3 of the present invention;

[0033] Figure 2 is the NaCl resistance of the thickener molecule Q5 in Example 4 of the present invention;

[0034] Figure 3 MgCl2 resistance of thickener molecule Q5 of Example 4 of the present invention;

[0035] Figure 4 is the CaCl2 resistance of the thickener molecule Q5 of Example 4 of the present invention;

[0036] Figure 5 This is the shear resistance of the thickener molecule Q4 in Example 5 of the present invention. DETAILED DESCRIPTION

[0037] The following further describes the claims of the present invention in detail in conjunction with specific embodiments, but does not constitute any limitation to the present invention. Any limited modifications made by anyone within the scope of the claims of the present invention are still within the scope of the claims of the present invention.

[0038] Example 1

[0039] The present embodiment provides a method for preparing a cationic thickener, which specifically comprises the following steps:

[0040] (1) Weigh 12.06 g of acrylamide, 15.53 g of methacryloyloxyethyltrimethylammonium chloride, 0.05 g of cationic double-chain monomer B, and 1.42 g of sodium lauryl sulfate, and dissolve them in 55 mL of deionized water;

[0041] (2) Add 0.005 g of tetramethylethylenediamine to the aqueous solution in (1) and dissolve it. Adjust the pH of the solution to neutral with sodium carbonate. Pour the solution into the reactor and introduce nitrogen for 40 minutes.

[0042] (3) Weigh 0.05 g of azobisisobutyronitrile and dissolve it in 15 mL of deionized water to obtain an initiator solution;

[0043] (4) The air in the reactor in step (2) was removed and the initiator solution in step (3) was added dropwise. At the same time, the system temperature was raised to 60 ° C and the reaction was continued for 10h;

[0044] (5) The white colloidal substance was cut into pieces, washed three times with anhydrous ethanol, and then dried in a vacuum oven at 75°C for 24 h.

[0045] The preparation method of cationic double-chain monomer B comprises the following steps: weighing 1.0 mol of diallylamine and 1.0 mol of potassium carbonate, adding 50 ml of ethanol and mixing evenly, stirring for 10 minutes, controlling the temperature to 70°C, then dropping 2.2 mol of tetradecane bromide into the solution, reacting for 8 hours after the addition is completed, adjusting the temperature to 50°C, reacting for 24 hours, cooling to room temperature, filtering, and rotary evaporation to obtain a light yellow associative active material, which is set aside for later use.

[0046] The thickener prepared in this example is recorded as Q1, and its molecular weight can reach about 4.436 million. The testing method refers to the national standards "GB / T 12005.1-1989 Polyacrylamide Intrinsic Viscosity Determination Method" and "GB / T 12005.10-1992 Polyacrylamide Molecular Weight Determination Viscosity Method".

[0047] Example 2

[0048] The present embodiment provides a method for preparing a cationic thickener, which specifically comprises the following steps:

[0049] (1) Weigh 22.07 g of acrylamide, 2.98 g of methacryloyloxyethyltrimethylammonium chloride, 1.60 g of cationic double-chain monomer B, and 0.49 g of sodium dodecylsulfonate, and dissolve them in 55 mL of deionized water;

[0050] (2) Add 0.049 g of N,N'-methylenebisacrylamide to the aqueous solution in (1) and dissolve it. Adjust the pH of the solution to neutral with sodium carbonate. Pour the solution into the reactor and introduce nitrogen for 40 minutes.

[0051] (3) Weigh 0.001 g of ammonium persulfate and dissolve it in 18 mL of deionized water to obtain an initiator solution;

[0052] (4) The air in the reactor in step (2) was removed and the initiator solution in step (3) was added dropwise. At the same time, the system temperature was raised to 80 ° C and the reaction was continued for 2h;

[0053] (5) The white colloidal substance was cut into pieces, washed three times with anhydrous ethanol, and then dried in a vacuum oven at 100 °C for 6 h.

[0054] The preparation method of cationic double-chain monomer B comprises the following steps: weighing 1.0 mol of diallylamine and 1.0 mol of potassium carbonate, adding 50 ml of ethanol and mixing evenly, stirring for 15 minutes, controlling the temperature at 60°C, and then dropping 2.0 mol of dodecyl bromide into the solution. After the addition is complete, the mixture is reacted for 10 hours, the temperature is adjusted to 40°C, and the mixture is reacted for 30 hours, and then cooled to room temperature. After filtering and rotary evaporation, a light yellow associative active substance is obtained, which is then set aside for later use.

[0055] The thickener prepared in this example is recorded as Q2, and its molecular weight can reach about 3.264 million. The testing method refers to the national standards "GB / T 12005.1-1989 Polyacrylamide Intrinsic Viscosity Determination Method" and "GB / T 12005.10-1992 Polyacrylamide Molecular Weight Determination Viscosity Method".

[0056] Example 3

[0057] The present embodiment provides a method for preparing a cationic thickener, which specifically comprises the following steps:

[0058] (1) Weigh 19.32 g of acrylamide, 2.38 g of methacryloyloxyethyltrimethylammonium chloride, 3.00 g of cationic double-chain monomer B, and 3.02 g of sodium lauryl sulfate, and dissolve them in 60 mL of deionized water;

[0059] (2) Add 0.10 g of tetramethylethylenediamine to the aqueous solution in (1) and dissolve it. Adjust the pH of the solution to neutral with sodium carbonate. Pour the solution into the reactor and introduce nitrogen for 40 minutes.

[0060] (3) Weigh 0.10 g of potassium persulfate and sodium thiosulfate and dissolve them in 12 mL of deionized water to obtain an initiator solution;

[0061] (4) After the air in the reactor in step (2) is completely removed, the initiator solution in step (3) is added dropwise. At the same time, the system temperature is raised to 30°C and the reaction is carried out for 20 hours.

[0062] (5) The white colloidal substance was cut into pieces, washed three times with anhydrous ethanol, and then dried in a vacuum oven at 50°C for 48 h.

[0063] The preparation method of cationic double-chain monomer B comprises the following steps: weighing 1.0 mol of diallylamine and 1.0 mol of potassium carbonate, adding 50 ml of ethanol and mixing evenly, stirring for 30 minutes, controlling the temperature to 80°C, then dropping 2.5 mol of hexadecane bromide into the solution, reacting for 6 hours after the addition is completed, adjusting the temperature to 60°C, reacting for 18 hours, cooling to room temperature, filtering, and rotary evaporation to obtain a light yellow associative active material, which is set aside for later use.

[0064] The thickener prepared in this example is denoted as Q3, and its molecular weight can reach about 2.868 million. The test method refers to the national standards "GB / T 12005.1-1989 Polyacrylamide Intrinsic Viscosity Determination Method" and "GB / T 12005.10-1992 Polyacrylamide Molecular Weight Determination Viscosity Method". The infrared spectrum of the thickener molecule is shown in Figure 1 .

[0065] Example 4

[0066] The present embodiment provides a method for preparing a cationic thickener, which specifically comprises the following steps:

[0067] (1) Weigh 16.46 g of acrylamide, 7.25 g of methacryloyloxyethyltrimethylammonium chloride, 2.02 g of cationic double-chain monomer B, and 2.39 g of sodium lauryl sulfate, and dissolve them in 55 mL of deionized water;

[0068] (2) Add 0.072 g of tetramethylethylenediamine to the aqueous solution in (1) and dissolve it. Adjust the pH of the solution to neutral with sodium carbonate. Pour the solution into the reactor and introduce nitrogen for 40 minutes.

[0069] (3) Weigh 0.054 g of azobisisobutylamidine hydrochloride and dissolve it in 14 mL of deionized water to obtain an initiator solution;

[0070] (4) After the air in the reactor in step (2) is completely removed, the initiator solution in step (3) is added dropwise. At the same time, the system temperature is raised to 50°C and the reaction is carried out for 16 hours.

[0071] (5) The white colloidal substance was cut into pieces, washed three times with anhydrous ethanol, and then dried in a vacuum oven at 80 °C for 18 h.

[0072] The preparation method of the cationic double-chain monomer B in this embodiment is the same as the preparation method of the cationic double-chain monomer B described in Example 2.

[0073] The thickener prepared in this example is recorded as Q4, and its molecular weight can reach about 5.543 million. The testing method refers to the national standards "GB / T 12005.1-1989 Polyacrylamide Intrinsic Viscosity Determination Method" and "GB / T 12005.10-1992 Polyacrylamide Molecular Weight Determination Viscosity Method".

[0074] Example 5

[0075] The present embodiment provides a method for preparing a cationic thickener, which specifically comprises the following steps:

[0076] (1) Weigh 15.09 g of acrylamide, 10.47 g of methacryloyloxyethyltrimethylammonium chloride, 1.04 g of cationic double-chain monomer B, and 1.54 g of sodium dodecylsulfonate, and dissolve them in 57 mL of deionized water;

[0077] (2) Add 0.04 g of diethylamine to the aqueous solution in (1) and dissolve it. Adjust the pH of the solution to neutral with sodium carbonate. Pour the solution into the reactor and introduce nitrogen for 40 minutes.

[0078] (3) Weigh 0.05 g of potassium persulfate and dissolve it in 14 mL of deionized water to obtain an initiator solution;

[0079] (4) The air in the reactor in step (2) was completely removed and the initiator solution in step (3) was added dropwise. At the same time, the system temperature was raised to 65°C and the reaction was continued for 8 hours.

[0080] (5) The white colloidal substance was cut into pieces, washed three times with anhydrous ethanol, and then dried in a vacuum oven at 60 °C for 32 h.

[0081] The preparation method of the cationic double-chain monomer B in this embodiment is the same as the preparation method of the cationic double-chain monomer B described in Example 2.

[0082] The thickener prepared in this example is recorded as Q5, and its molecular weight can reach about 6.011 million. The testing method refers to the national standards "GB / T 12005.1-1989 Polyacrylamide Intrinsic Viscosity Determination Method" and "GB / T 12005.10-1992 Polyacrylamide Molecular Weight Determination Viscosity Method".

[0083] Comparative Example 1

[0084] The preparation process of this embodiment is exactly the same as that of the above embodiment 1, except that the cationic double-chain monomer B is not added.

[0085] (1) Weigh 13.82 g of acrylamide, 13.46 g of methacryloyloxyethyltrimethylammonium chloride, 0.00 g of cationic double-chain monomer B, and 0.96 g of sodium lauryl sulfate, and dissolve them in 56 mL of deionized water;

[0086] (2) Add 0.019 g of tetramethylethylenediamine to the aqueous solution in (1) and dissolve it. Adjust the pH of the solution to neutral with sodium carbonate. Pour the solution into the reactor and introduce nitrogen for 40 minutes.

[0087] (3) Weigh 0.027 g of potassium persulfate and dissolve it in 16 mL of deionized water;

[0088] (4) After the air in the reactor in step (2) is completely removed, the initiator solution in step (3) is added dropwise. At the same time, the system temperature is raised to 75°C and the reaction is carried out for 5 hours.

[0089] (5) The white colloidal substance was cut into pieces, washed three times with anhydrous ethanol, and then dried in a vacuum oven at 80 °C for 18 h.

[0090] The thickener prepared in this example is denoted as P1, and its molecular weight can reach about 4.624 million. The testing method refers to the national standards "GB / T 12005.1-1989 Polyacrylamide Intrinsic Viscosity Determination Method" and "GB / T 12005.10-1992 Polyacrylamide Molecular Weight Determination Viscosity Method".

[0091] In order to demonstrate the advantages of the technical solution provided by this application, the following is a test experiment on the cationic thickener provided by this application:

[0092] 1. Infrared spectrum

[0093] Infrared spectrum test method: Take a small amount of the thickener prepared in Example 3 and mix it evenly with the dried KBr. Use a mortar to grind the thickener and KBr solid into powder. Use a tableting method and use an infrared spectrometer to perform infrared spectrum testing on the thickener. The test wavelength range is 500~4000nm.

[0094] Test results refer to Figure 1 ,from Figure 1 The infrared spectrum shows that 2923 cm -1 and 2853 cm -1 The peak at 3181 cm is attributed to the stretching vibration of long-chain alkane -CH2-. -1 、3401 cm -1 and 1680 cm -1 The peaks are attributed to NH and C=O in the amide group, 1045 cm -1 The peak at is attributed to N + The characteristic absorption peak of (CH3)3 is 1177 cm -1 The peak at 1453 cm is attributed to the stretching vibration absorption peak of CO. -1 The peaks are attributed to -CH2-N + The bending vibration of -CH2- in the mixture indicates that the thickener was successfully synthesized.

[0095] 2. Salt tolerance

[0096] Test method: 50 mL of Example Q5 thickener solution was prepared with distilled water to a mass concentration of 0.6 wt% for standby use. The test instrument was a rotational rheometer (MCR 702e), the test temperature was 25°C, the rotor model was CP40-1, and the constant shear rate was 170 s. -1 Under the conditions of , the apparent viscosity of the thickener solution of Example Q5 was tested.

[0097] Table 1

[0098]

[0099] The poor salt resistance of thickeners is a pain point in the application of thickeners in oil fields. By introducing hydrophobic monomers to form a spatial network structure of the thickener, the fluid dynamics volume of the thickener in water can be increased, the viscosity of the thickener solution can be increased, and thus its salt resistance can be improved. Table 1 shows that with the increase of salt concentration, the apparent viscosity of Q5 and P1 decreases, but the apparent viscosity of Q5 is much greater than that of P1, indicating that the salt resistance of Q5 is better than that of P1. The apparent viscosity of Q5 and P1 thickener solutions in MgCl2 solution is higher than that in CaCl2 solution. Figure 2-Figure 4 It can be seen that as the salt concentration increases, the thickener molecular chains curl, the solubility decreases, and the viscosity decreases. Q5 has better salt tolerance than P1. When the NaCl concentration reaches 20,000 mg / L, the apparent viscosity of Q5 can still reach 61 mPa·s, while the apparent viscosity of P1 is only 33 mPa·s. When the MgCl2 concentration reaches 2000 mg / L, the apparent viscosity of Q5 can still reach 62 mPa·s, while the apparent viscosity of P1 is only 31 mPa·s. When the CaCl2 concentration reaches 2000 mg / L, the apparent viscosity of Q5 can still reach 60 mPa·s, while the apparent viscosity of P1 is only 28 mPa·s.

[0100] 3. Shear resistance

[0101] Shear resistance test method: A rotational rheometer (MCR 702e) was used at a constant temperature of 25°C. A 0.6 wt % thickener solution of Example Q4 was used to test the effect of shear rate on the shear stress of the thickener solution at different shear rates.

[0102] Test results see Figure 5 ,from Figure 5 It can be seen that under external shear force, the thixotropic loop of the thickener solution is very small, and the rate of structural destruction and structural recovery of the thickener solution are basically equal. The thickener solution structure has instantaneous recovery performance, and the hysteresis of recovery is negligible. In addition, the shear stress of the thickener solution gradually increases with increasing shear rate, indicating that the energy required to destroy the thickener solution gradually increases. The spatial interpenetrating network structure formed by thickener solution Q4 is the densest and has the greatest network strength.

Claims

1. A cationic thickener, characterized in that: The structural formula is shown in Formula 1: ； Formula 1 Where: x=1-98000, y=1-6000, z=1-2000; R1 is a (C12-C22) alkane group; R2 is a (C12-C22) alkane group; It is prepared by the following steps in sequence: (1) Weigh acrylamide, cationic monomer A, cationic double-chain monomer B, and surfactant, and dissolve them in deionized water; (2) Add the catalyst to the aqueous solution in (1) and dissolve it, adjust the pH of the solution to neutral, pour it into the reactor and introduce nitrogen; (3) Weigh the initiator and dissolve it in deionized water; (4) Remove all the air from the reactor in step (2) and start adding the initiator solution in step (3) dropwise. At the same time, heat the system to 30-80°C and react for 2-20 hours. (5) The white colloidal substance was cut into pieces, washed several times with anhydrous ethanol, and then dried in a vacuum oven. The mass ratio of acrylamide, cationic monomer A, cationic double-chain monomer B, surfactant, catalyst, and initiator is: 12.0-22.0: 3.0-15.0: 0.05-3.0: 0.5-3.0: 0.005-0.1: 0.001-0.1; The cationic double-chain monomer B is a diallyl quaternary ammonium salt derivative; The cationic double-chain monomer B is prepared by the following method: 1.0 mol of diallylamine, 1.0 mol of potassium carbonate and ethanol are weighed and mixed evenly, stirred for 10-30 minutes, and the temperature is controlled at 60-80°C. 2.0-2.5 mol of bromoalkane is then added dropwise to the solution. After the addition is complete, the reaction is carried out for 6-10 hours. The temperature is adjusted to 40-60°C, and the reaction is carried out for 18-30 hours. The mixture is cooled to room temperature, filtered, and rotary evaporated to obtain a light yellow associative active material, which is then set aside for later use.

2. The method for preparing a cationic thickener according to claim 1, characterized in that: The method includes the following steps in sequence: (1) Weigh acrylamide, cationic monomer A, cationic double-chain monomer B, and surfactant, and dissolve them in deionized water; (2) Add the catalyst to the aqueous solution in (1) and dissolve it, adjust the pH of the solution to neutral, pour it into the reactor and introduce nitrogen; (3) Weigh the initiator and dissolve it in deionized water; (4) Remove all the air from the reactor in step (2) and start adding the initiator solution in step (3) dropwise. At the same time, heat the system to 30-80°C and react for 2-20 hours. (5) The white colloidal substance was cut into pieces, washed several times with anhydrous ethanol, and then dried in a vacuum oven. The mass ratio of acrylamide, cationic monomer A, cationic double-chain monomer B, surfactant, catalyst, and initiator is: 12.0-22.0: 3.0-15.0: 0.05-3.0: 0.5-3.0: 0.005-0.1: 0.001-0.1; The cationic double-chain monomer B is a diallyl quaternary ammonium salt derivative; The cationic double-chain monomer B is prepared by the following method: 1.0 mol of diallylamine, 1.0 mol of potassium carbonate and ethanol are weighed and mixed evenly, stirred for 10-30 minutes, and the temperature is controlled at 60-80°C. 2.0-2.5 mol of bromoalkane is then added dropwise to the solution. After the addition is complete, the reaction is carried out for 6-10 hours. The temperature is adjusted to 40-60°C, and the reaction is carried out for 18-30 hours. The mixture is cooled to room temperature, filtered, and rotary evaporated to obtain a light yellow associative active material, which is then set aside for later use.

3. The method for preparing a cationic thickener according to claim 2, characterized in that: The cationic monomer A is methacryloyloxyethyl trimethylammonium chloride.

4. The method for preparing a cationic thickener according to claim 2, wherein: The surfactant is at least one of dodecylaminopropionic acid, octadecylamidopropylamine oxide, dodecyldimethylsulfopropyl betaine, hexadecyltrimethylammonium chloride, dodecylethoxysulfobetaine, tetradecylamidopropylhydroxypropylsulfobetaine, octadecyldihydroxyethylamine oxide, sodium lauryl sulfate, dodecyldimethylhydroxypropylsulfobetaine, hexadecyldimethylhydroxypropylphosphate betaine, lauryl alcohol polyoxyethylene ether 2-acrylamido-2-dimethylpropanesulfonic acid, and decyldimethylhydroxypropylsulfobetaine.

5. The method for preparing a cationic thickener according to claim 2, characterized in that: The catalyst is at least one of 1,4-bis(hydroxyethyl)piperazine, tetramethylethylenediamine, diethylamine, dimethylaminopropionitrile, diethylamino anhydrous ethanol and N,N'-methylenebisacrylamide.

6. The method for preparing a cationic thickener according to claim 2, characterized in that: The initiator is at least one of sodium bisulfite, sodium thiosulfate, dicyclohexyl peroxydicarbonate, ammonium persulfate, azobisisobutyronitrile, azobisisobutylimidazoline hydrochloride, azobisisobutylamidine hydrochloride, potassium persulfate, azobiscyanovaleric acid, azobisisopropylimidazoline, and sodium persulfate.

7. The method for preparing a cationic thickener according to claim 2, characterized in that: The vacuum drying temperature in step (5) is 50-100°C, and the drying time is 6-48h.

8. The method for preparing a cationic thickener according to claim 2, characterized in that: The pH value of the solution in step (2) is adjusted by using sodium carbonate.

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