High-temperature-resistant polyanionic cellulose and preparation method thereof

Abstract

The invention relates to the technical field of polymer functional materials, and discloses high-temperature-resistant polyanionic cellulose and a preparation method thereof.The preparation method of the high-temperature-resistant polyanionic cellulose comprises the steps that graft modified cellulose is dispersed in isopropanol and stirred to obtain suspension liquid, a sodium hydroxide aqueous solution is dropwise added into the suspension liquid, and the suspension liquid is stirred to be uniform; the preparation method comprises the following steps: adding sodium hydroxide into a reaction kettle, stirring for 1-2 hours at 35-40 DEG C for alkalization, then adding sodium chloroacetate, stirring for reaction for 3-4 hours at 65-75 DEG C, cooling to room temperature after the reaction is finished, adjusting the pH value to 7-8 by using diluted hydrochloric acid, pouring a reactant into an ethanol aqueous solution, stirring to precipitate a product, performing suction filtration, washing until a filtrate does not contain chloride ions, performing vacuum drying for 20-24 hours at 60-70 DEG C, crushing, and sieving by a 100-120-mesh sieve to obtain the product. The high-temperature-resistant polyanionic cellulose is obtained. The polyanionic cellulose prepared by the invention has good high temperature resistance, salt resistance and filtrate loss reduction effect.

Description

Technical Field

[0001] This invention relates to the field of polymer functional materials technology, specifically to a high-temperature resistant polyanionic cellulose and its preparation method. Background Technology

[0002] Polyanionic cellulose plays a crucial role in drilling fluid treatment agents due to its excellent water solubility, thickening properties, and suspension stability. However, as global oil and gas resource exploitation extends to deeper and ultra-deep formations, the extraction environment becomes increasingly harsh. Traditional polyanionic cellulose exhibits significant performance deficiencies under harsh conditions of high temperature and high salinity. The glycosidic bonds in the polyanionic cellulose molecular chain are prone to breakage and degradation at high temperatures, leading to a sharp decrease in drilling fluid viscosity. In high-salt environments, the molecular chains aggregate and flocculate, further diminishing their thickening and filtration loss reduction functions. Therefore, avoiding this phenomenon is key to solving the problem. For example, patent application CN109929041A discloses a method for preparing polyanionic cellulose. This method uses urea as a cellulose activating agent, effectively improving the reactivity of cellulose, lowering the alkalization reaction temperature, and enhancing the adsorption of alkali by cellulose. However, its high-temperature resistance and salt resistance still need improvement. Summary of the Invention

[0003] In order to overcome the shortcomings of the prior art, the present invention aims to provide a high-temperature resistant polyanionic cellulose and its preparation method. The polyanionic cellulose prepared by the present invention has good high-temperature resistance, salt resistance and filtration loss reduction effect.

[0004] To achieve the above objectives, the present invention provides the following technical solution: a method for preparing high-temperature resistant polyanionic cellulose, comprising the following steps: (1) Preparation of 2,7-bis(4-nitrophenoxy)naphthalene: 2,7-bis(4-nitrophenoxy)naphthalene is obtained by reacting p-nitrochlorobenzene and 2,7-dihydroxynaphthalene; (2) Preparation of 2,7-bis(4-aminophenoxy)naphthalene: The nitro group of 2,7-bis(4-nitrophenoxy)naphthalene was reduced to amino group to obtain 2,7-bis(4-aminophenoxy)naphthalene; (3) Preparation of intermediate 1: 2,7-bis(4-aminophenoxy)naphthalene and 2-acrylamido-2-methylpropanesulfonic acid undergo Michael addition reaction to obtain intermediate 1 retaining a primary amino group; (4) Preparation of epoxy cellulose: cellulose reacts with glycidyl methacrylate to obtain epoxy cellulose; (5) Preparation of grafted modified cellulose: Intermediate 1 reacts with epoxy cellulose to obtain grafted modified cellulose; (6) Preparation of high temperature resistant polyanionic cellulose: Grafted modified cellulose is etherified with sodium chloroacetate to obtain high temperature resistant polyanionic cellulose.

[0005] Further, in step (1), the preparation method of 2,7-bis(4-nitrophenoxy)naphthalene is as follows: 10.4-10.5g of 2,7-dihydroxynaphthalene, 19.8-19.9g of p-nitrochlorobenzene, 17.3-17.4g of anhydrous potassium carbonate, 15-17mL of toluene, and 150-160mL of N,N-dimethylformamide are added to a reactor, stirred and mixed, and reacted at 140-150℃ for 9-12h. Then, the temperature is raised to 150-160℃ and reacted for 1-1.5h. After the reaction is completed, the mixture is filtered while hot. After the filtrate is allowed to stand for 10-12h, the precipitate crystallized in the filtrate is filtered out. The precipitate is washed with water 3-4 times and then dried in an oven at 55-65℃ to obtain 2,7-bis(4-nitrophenoxy)naphthalene.

[0006] In the above steps, under the action of alkali, the chlorine in p-nitrochlorobenzene reacts with the hydroxyl group in 2,7-dihydroxynaphthalene, and the chloride ion is replaced as a leaving group to form a new CO ether bond. Two phenoxy groups with nitro groups are introduced at both ends of the rigid naphthalene ring to obtain 2,7-bis(4-nitrophenoxy)naphthalene.

[0007] Further, in step (2), the preparation method of 2,7-bis(4-aminophenoxy)naphthalene is as follows: under nitrogen protection, 15-16g of 2,7-bis(4-nitrophenoxy)naphthalene, 2.25-2.35g of ferric chloride, 7.5-7.6g of activated carbon, and 115-125mL of ethylene glycol methyl ether are added to the reactor, mixed evenly, and reacted at 100-110℃ for 8-12h. After the reaction is completed, the mixture is filtered while hot. After the filtrate is cooled to room temperature, it is rotary evaporated at 75-85℃. Then, the concentrated liquid is poured into 300-350mL of deionized water to precipitate the precipitate. The precipitate is filtered, washed, and dried to obtain 2,7-bis(4-aminophenoxy)naphthalene.

[0008] In the above steps, under the catalytic action of ferric chloride and activated carbon, the nitro group is reduced to an amino group to obtain 2,7-bis(4-aminophenoxy)naphthalene.

[0009] Further, in step (3), the preparation method of intermediate 1 is as follows: under nitrogen gas protection and an ice-water bath at 0-5℃, 40-45 mL of deionized water and 40-45 mL of anhydrous ethanol are added to the reactor and mixed to obtain a solvent. Then, 10-10.1 g of 2,7-bis(4-aminophenoxy)naphthalene and 0.02-0.022 g of hydroquinone are added to it and mixed evenly to form a suspension. At the same time, 4.1-4.2 g of 2 Acrylamide-2-methylpropanesulfonic acid was dissolved in 15-20 mL of deionized water to obtain an aqueous sulfonic acid solution. The aqueous sulfonic acid solution was added dropwise to the suspension with stirring over a period of 4-6 hours. After the addition was complete, the mixture was stirred and reacted in an ice-water bath at 0-5°C for 12-16 hours. After the reaction was completed, the mixture was rotary evaporated at 25-35°C. The concentrated solution was then poured into 200-220 mL of acetone to precipitate the precipitate. The precipitate was filtered, washed, and dried to obtain intermediate 1.

[0010] In the above steps, hydroquinone was used in an ice-water bath at 0-5°C to inhibit the free radical homopolymerization of the carbon-carbon double bond in 2-acrylamido-2-methylpropanesulfonic acid, ensuring that the reaction proceeds via the Michael addition pathway. One of the primary amino groups in 2,7-bis(4-aminophenoxy)naphthalene acts as a nucleophile, attacking the β-carbon of the acryloyl group in 2-acrylamido-2-methylpropanesulfonic acid to form a stable amide bond, yielding intermediate 1 that retains one primary amino group.

[0011] Further, in step (4), the preparation method of epoxy cellulose is as follows: under nitrogen gas protection, 80-82g of 1-butyl-3-methylimidazolium chloride and 4-4.1g of microcrystalline cellulose are added to the reactor and mixed and dissolved at 25-35℃. Then, 0.1-0.11g of potassium persulfate is added and stirred for 30-40min. Then, 3.51-3.55g of glycidyl methacrylate is added dropwise. After the addition is completed, the reaction is stirred for 3-4h. After the reaction is completed, the reaction solution is poured into 300-400mL of anhydrous ethanol to precipitate. The solid is collected by suction filtration and washed until there are no chloride ions in the filtrate. The solid is then vacuum dried at 55-65℃ for 24-28h to obtain epoxy cellulose.

[0012] In the above steps, under the action of potassium persulfate initiator, the free radicals of cellulose macromolecules attack the carbon-carbon double bonds of glycidyl methacrylate, resulting in an addition reaction. The glycidyl methacrylate segments with epoxy groups are grafted onto cellulose to obtain epoxy cellulose.

[0013] Further, in step (5), the preparation method of grafted modified cellulose is as follows: 3-3.1g of epoxy cellulose and 4.4-4.5g of intermediate 1 are added to 70-80mL of anhydrous dimethyl sulfoxide solvent, mixed evenly, and stirred at 60-70℃ for 16-20h. After the reaction is completed, the mixture is cooled to room temperature, and the reaction solution is poured into 300-400mL of acetone to precipitate. The precipitate is filtered, washed with ethanol 3-4 times, and vacuum dried at 60-70℃ for 24-26h to obtain grafted modified cellulose.

[0014] In the above steps, the primary amino group retained in intermediate 1 acts as a nucleophile, attacking the carbon atom with less steric hindrance on the epoxy ring of epoxy cellulose, causing the epoxy ring to open and forming a new CN bond, while generating a hydroxyl group. Intermediate 1 is precisely grafted onto the cellulose backbone in the form of a covalent bond to obtain grafted modified cellulose.

[0015] Further, in step (6), the preparation method of high-temperature resistant polyanionic cellulose is as follows: 2.5-2.6g of grafted modified cellulose is dispersed in 40-50mL of isopropanol, stirred to obtain a suspension, and 6-7mL of 30% sodium hydroxide aqueous solution is added dropwise. The mixture is stirred at 35-40℃ for 1-2h for alkalization. Then, 3.5-3.6g of sodium chloroacetate is added, and the mixture is stirred at 65-75℃ for 3-4h. After the reaction is completed, the mixture is cooled to room temperature, and the pH is adjusted to 7-8 with 1mol / L dilute hydrochloric acid. The reactants are poured into 200-250mL of 80% ethanol aqueous solution, stirred to precipitate the product, filtered, washed until there are no chloride ions in the filtrate, vacuum dried at 60-70℃ for 20-24h, pulverized, and passed through a 100-120 mesh sieve to obtain high-temperature resistant polyanionic cellulose.

[0016] In the above steps, sodium hydroxide deprotonates the remaining primary hydroxyl groups on the cellulose backbone to generate a strongly nucleophilic cellulose oxygen anion, which attacks the methylene carbon in sodium chloroacetate and undergoes a nucleophilic substitution reaction, further introducing carboxymethyl groups into the grafted modified cellulose to obtain high-temperature resistant polyanionic cellulose.

[0017] This invention also protects a high-temperature resistant polyanionic cellulose, which is prepared by any of the preparation methods described above.

[0018] Compared with the prior art, the present invention has the following beneficial technical effects: This invention constructs a synergistic functional system of a rigid framework and strong hydrophilic groups by grafting a rigid naphthalene core structure and sulfonic acid groups onto the cellulose molecular chain. The rigid naphthalene core, as the aromatic structural core, effectively inhibits the breaking of cellulose glycosidic bonds and excessive chain coiling at high temperatures, significantly enhancing the rigidity and thermodynamic stability of the polymer molecular chain, thus improving the high-temperature resistance of polyanionic cellulose. The sulfonic acid groups, as strong hydrophilic groups, have higher charge density and stronger hydration capacity, forming a dense and salt-resistant hydration layer around the molecular chain. This effectively resists the compression and damage to the hydration layer caused by high concentrations of ions in saturated brine, thereby enhancing the salt resistance of polyanionic cellulose. The polyanionic cellulose of this invention, with its excellent thickening properties and high-temperature stability, can form a dense, tough, and low-permeability filter cake during drilling, effectively preventing drilling fluid leakage into the formation and improving its filtration loss reduction performance. Attached Figure Description

[0019] Figure 1 This is the synthesis reaction formula for intermediate 1. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] Example 1

[0022] (1) Add 10.4g of 2,7-dihydroxynaphthalene, 19.8g of p-nitrochlorobenzene, 17.3g of anhydrous potassium carbonate, 15mL of toluene, and 150mL of N,N-dimethylformamide to the reactor, stir and mix, react at 140℃ for 9h, then raise the temperature to 150℃ for 1h, filter while hot after the reaction, let the filtrate stand for 10h, filter out the precipitate crystallized in the filtrate, wash the precipitate with water 3 times, and dry it in an oven at 55℃ to obtain 2,7-bis(4-nitrophenoxy)naphthalene; (2) Under nitrogen protection, 15g of 2,7-bis(4-nitrophenoxy)naphthalene, 2.25g of ferric chloride, 7.5g of activated carbon and 115mL of ethylene glycol methyl ether were added to the reactor and mixed evenly. The mixture was reacted at 100℃ for 8h. After the reaction was completed, the mixture was filtered while hot. After the filtrate was cooled to room temperature, it was rotary evaporated at 75℃. The concentrated solution was then poured into 300mL of deionized water to precipitate the precipitate. The precipitate was filtered, washed and dried to obtain 2,7-bis(4-aminophenoxy)naphthalene. (3) Under nitrogen gas protection and a 0°C ice-water bath, 40 mL of deionized water and 40 mL of anhydrous ethanol were added to the reactor and mixed to prepare a solvent. Then, 10 g of 2,7-bis(4-aminophenoxy)naphthalene and 0.02 g of hydroquinone were added and mixed evenly to form a suspension. At the same time, 4.1 g of 2-acrylamide-2-methylpropanesulfonic acid was dissolved in 15 mL of deionized water to obtain a sulfonic acid aqueous solution. The sulfonic acid aqueous solution was added dropwise to the suspension with stirring over a period of 4 h. After the addition was completed, the reaction was continued for 12 h with stirring in a 0°C ice-water bath. After the reaction was completed, rotary evaporation was performed at 25°C. The concentrated liquid was then poured into 200 mL of acetone to precipitate the precipitate. The precipitate was filtered, washed, and dried to obtain intermediate 1, as shown in the figure. Figure 1 As shown; (4) Under nitrogen protection, 80g of 1-butyl-3-methylimidazolium chloride and 4g of microcrystalline cellulose were added to the reactor and mixed and dissolved at 25°C. Then, 0.1g of potassium persulfate was added and stirred for 30min. Then, 3.51g of glycidyl methacrylate was added dropwise. After the addition was completed, the reaction was stirred for 3h. After the reaction was completed, the reaction solution was poured into 300mL of anhydrous ethanol to precipitate. The solid was collected by suction filtration and washed until there were no chloride ions in the filtrate. The solid was dried under vacuum at 55°C for 24h to obtain epoxy cellulose. (5) Add 3g of epoxy cellulose and 4.4g of intermediate 1 to 70mL of anhydrous dimethyl sulfoxide solvent, mix well, stir at 60℃ for 16h, after the reaction is completed, cool to room temperature, pour the reaction solution into 300mL of acetone, precipitate, filter, wash 3 times with ethanol, and vacuum dry at 60℃ for 24h to obtain grafted modified cellulose. (6) 2.5 g of grafted modified cellulose was dispersed in 40 mL of isopropanol and stirred to obtain a suspension. 6 mL of 30% sodium hydroxide aqueous solution was added dropwise and stirred at 35 °C for 1 h for alkalization. Then 3.5 g of sodium chloroacetate was added and stirred at 65 °C for 3 h. After the reaction was completed, the mixture was cooled to room temperature and the pH was adjusted to 7 with 1 mol / L dilute hydrochloric acid. The reactants were poured into 200 mL of 80% ethanol aqueous solution and stirred to precipitate the product. The product was filtered and washed until no chloride ions were found in the filtrate. The product was vacuum dried at 60 °C for 20 h, pulverized, and passed through a 100-mesh sieve to obtain high-temperature resistant polyanionic cellulose.

[0023] Example 2

[0024] (1) Add 10.5g of 2,7-dihydroxynaphthalene, 19.9g of p-nitrochlorobenzene, 17.3g of anhydrous potassium carbonate, 15mL of toluene, and 150mL of N,N-dimethylformamide to the reactor, stir and mix, react at 140℃ for 9h, then raise the temperature to 150℃ for 1h, filter while hot after the reaction, let the filtrate stand for 10h, filter out the precipitate crystallized in the filtrate, wash the precipitate with water 3 times, and dry it in an oven at 55℃ to obtain 2,7-bis(4-nitrophenoxy)naphthalene; (2) Under nitrogen protection, 15g of 2,7-bis(4-nitrophenoxy)naphthalene, 2.25g of ferric chloride, 7.5g of activated carbon and 115mL of ethylene glycol methyl ether were added to the reactor and mixed evenly. The mixture was reacted at 100℃ for 8h. After the reaction was completed, the mixture was filtered while hot. After the filtrate was cooled to room temperature, it was rotary evaporated at 75℃. The concentrated solution was then poured into 300mL of deionized water to precipitate the precipitate. The precipitate was filtered, washed and dried to obtain 2,7-bis(4-aminophenoxy)naphthalene. (3) Under nitrogen gas protection and 5℃ ice-water bath, 45mL of deionized water and 45mL of anhydrous ethanol were added to the reactor and mixed to prepare a solvent. Then, 10.1g of 2,7-bis(4-aminophenoxy)naphthalene and 0.022g of hydroquinone were added to it and mixed evenly to form a suspension. At the same time, 4.2g of 2-acrylamide-2-methylpropanesulfonic acid was dissolved in 20mL of deionized water to obtain a sulfonic acid aqueous solution. The sulfonic acid aqueous solution was added dropwise to the suspension under stirring for 6h. After the addition was completed, the reaction was continued to be stirred for 16h while maintaining a 5℃ ice-water bath. After the reaction was completed, rotary evaporation was carried out at 35℃. Then, the concentrated liquid was poured into 220mL of acetone to precipitate the precipitate. The precipitate was filtered, washed and dried to obtain intermediate 1. (4) Under nitrogen protection, 82g of 1-butyl-3-methylimidazolium chloride and 4.1g of microcrystalline cellulose were added to the reactor and mixed and dissolved at 35°C. Then, 0.11g of potassium persulfate was added and stirred for 40min. Then, 3.55g of glycidyl methacrylate was added dropwise. After the addition was completed, the reaction was stirred for 4h. After the reaction was completed, the reaction solution was poured into 400mL of anhydrous ethanol to precipitate. The solid was collected by suction filtration and washed until there were no chloride ions in the filtrate. The solid was dried under vacuum at 65°C for 28h to obtain epoxy cellulose. (5) Add 3.1 g of epoxy cellulose and 4.5 g of intermediate 1 to 80 mL of anhydrous dimethyl sulfoxide solvent, mix well, stir at 70 °C for 20 h, cool to room temperature after the reaction is completed, pour the reaction solution into 400 mL of acetone, precipitate, filter, wash 4 times with ethanol, and vacuum dry at 70 °C for 26 h to obtain grafted modified cellulose. (6) 2.6 g of grafted modified cellulose was dispersed in 50 mL of isopropanol and stirred to obtain a suspension. 7 mL of 30% sodium hydroxide aqueous solution was added dropwise and stirred at 40 °C for 2 h for alkalization. Then 3.6 g of sodium chloroacetate was added and stirred at 75 °C for 4 h. After the reaction was completed, the mixture was cooled to room temperature and the pH was adjusted to 8 with 1 mol / L dilute hydrochloric acid. The reactants were poured into 250 mL of 80% ethanol aqueous solution and stirred to precipitate the product. The product was filtered and washed until there were no chloride ions in the filtrate. The product was vacuum dried at 70 °C for 24 h, pulverized, and passed through a 120 mesh sieve to obtain high-temperature resistant polyanionic cellulose.

[0025] Example 3

[0026] (1) Add 10.43g of 2,7-dihydroxynaphthalene, 19.83g of p-nitrochlorobenzene, 17.33g of anhydrous potassium carbonate, 16mL of toluene, and 153mL of N,N-dimethylformamide to the reactor, stir and mix, react at 143℃ for 10h, then raise the temperature to 153℃ and react for 1h. After the reaction is completed, filter while hot, let the filtrate stand for 11h, filter out the precipitate crystallized in the filtrate, wash the precipitate with water 3 times, and dry it in an oven at 58℃ to obtain 2,7-bis(4-nitrophenoxy)naphthalene; (2) Under nitrogen protection, 15.3 g of 2,7-bis(4-nitrophenoxy)naphthalene, 2.28 g of ferric chloride, 7.53 g of activated carbon and 118 mL of ethylene glycol methyl ether were added to the reactor and mixed evenly. The mixture was reacted at 103 °C for 9 h. After the reaction was completed, the mixture was filtered while hot. After the filtrate cooled to room temperature, it was rotary evaporated at 78 °C. The concentrated solution was then poured into 320 mL of deionized water to precipitate the precipitate. The precipitate was filtered, washed and dried to obtain 2,7-bis(4-aminophenoxy)naphthalene. (3) Under nitrogen gas protection and 2℃ ice-water bath, 42mL of deionized water and 42mL of anhydrous ethanol were added to the reactor and mixed to prepare a solvent. Then, 10.03g of 2,7-bis(4-aminophenoxy)naphthalene and 0.02g of hydroquinone were added to it and mixed evenly to form a suspension. At the same time, 4.13g of 2-acrylamide-2-methylpropanesulfonic acid was dissolved in 17mL of deionized water to obtain a sulfonic acid aqueous solution. The sulfonic acid aqueous solution was added dropwise to the suspension under stirring for 5h. After the addition was completed, the reaction was continued to be stirred for 14h while maintaining the 2℃ ice-water bath. After the reaction was completed, rotary evaporation was carried out at 28℃. Then, the concentrated liquid was poured into 208mL of acetone to precipitate the precipitate. The precipitate was filtered, washed and dried to obtain intermediate 1. (4) Under nitrogen protection, 81g of 1-butyl-3-methylimidazolium chloride and 4.03g of microcrystalline cellulose were added to the reactor and mixed and dissolved at 28°C. Then, 0.1g of potassium persulfate was added and stirred for 33min. Then, 3.53g of glycidyl methacrylate was added dropwise. After the addition was completed, the reaction was stirred for 3h. After the reaction was completed, the reaction solution was poured into 330mL of anhydrous ethanol to precipitate. The solid was collected by suction filtration and washed until there were no chloride ions in the filtrate. The solid was dried under vacuum at 58°C for 26h to obtain epoxy cellulose. (5) Add 3.03 g of epoxy cellulose and 4.43 g of intermediate 1 to 73 mL of anhydrous dimethyl sulfoxide solvent, mix well, stir at 63 °C for 18 h, after the reaction is completed, cool to room temperature, pour the reaction solution into 330 mL of acetone, precipitate, filter, wash 3 times with ethanol, and vacuum dry at 63 °C for 25 h to obtain grafted modified cellulose; (6) 2.53 g of grafted modified cellulose was dispersed in 43 mL of isopropanol and stirred to obtain a suspension. 6.3 mL of 30% sodium hydroxide aqueous solution was added dropwise and stirred at 37 °C for 1 h for alkalization. Then, 3.53 g of sodium chloroacetate was added and stirred at 68 °C for 3 h. After the reaction was completed, the mixture was cooled to room temperature and the pH was adjusted to 7 with 1 mol / L dilute hydrochloric acid. The reactants were poured into 220 mL of 80% ethanol aqueous solution and stirred to precipitate the product. The product was filtered and washed until no chloride ions were found in the filtrate. The product was vacuum dried at 63 °C for 22 h, pulverized, and passed through a 110 mesh sieve to obtain high-temperature resistant polyanionic cellulose.

[0027] Example 4

[0028] (1) Add 10.47 g of 2,7-dihydroxynaphthalene, 19.87 g of p-nitrochlorobenzene, 17.37 g of anhydrous potassium carbonate, 16 mL of toluene, and 158 mL of N,N-dimethylformamide to the reactor, stir and mix, react at 148 °C for 11 h, then raise the temperature to 157 °C and react for 1.5 h. After the reaction is complete, filter while hot, let the filtrate stand for 12 h, filter out the precipitate crystallized in the filtrate, wash the precipitate with water 4 times, and dry it in an oven at 62 °C to obtain 2,7-bis(4-nitrophenoxy)naphthalene; (2) Under nitrogen protection, 15.7 g of 2,7-bis(4-nitrophenoxy)naphthalene, 2.32 g of ferric chloride, 7.57 g of activated carbon and 122 mL of ethylene glycol methyl ether were added to the reactor and mixed evenly. The mixture was reacted at 107 °C for 11 h. After the reaction was completed, the mixture was filtered while hot. After the filtrate was cooled to room temperature, it was rotary evaporated at 82 °C. The concentrated solution was then poured into 340 mL of deionized water to precipitate the precipitate. The precipitate was filtered, washed and dried to obtain 2,7-bis(4-aminophenoxy)naphthalene. (3) Under nitrogen gas protection and 3℃ ice-water bath, 44 mL of deionized water and 44 mL of anhydrous ethanol were added to the reactor and mixed to prepare a solvent. Then, 10.1 g of 2,7-bis(4-aminophenoxy)naphthalene and 0.022 g of hydroquinone were added to it and mixed evenly to form a suspension. At the same time, 4.17 g of 2-acrylamide-2-methylpropanesulfonic acid was dissolved in 19 mL of deionized water to obtain a sulfonic acid aqueous solution. The sulfonic acid aqueous solution was added dropwise to the suspension under stirring for 6 h. After the addition was completed, the reaction was continued to be stirred for 15 h while maintaining a 3℃ ice-water bath. After the reaction was completed, rotary evaporation was carried out at 32℃. Then, the concentrated liquid was poured into 220 mL of acetone to precipitate the precipitate. The precipitate was filtered, washed and dried to obtain intermediate 1. (4) Under nitrogen protection, 82g of 1-butyl-3-methylimidazolium chloride and 4.07g of microcrystalline cellulose were added to the reactor and mixed and dissolved at 32°C. Then, 0.11g of potassium persulfate was added and stirred for 37min. Then, 3.54g of glycidyl methacrylate was added dropwise. After the addition was completed, the reaction was stirred for 4h. After the reaction was completed, the reaction solution was poured into 380mL of anhydrous ethanol to precipitate. The solid was collected by suction filtration and washed until there were no chloride ions in the filtrate. The solid was dried under vacuum at 62°C for 27h to obtain epoxy cellulose. (5) Add 3.07 g of epoxy cellulose and 4.47 g of intermediate 1 to 78 mL of anhydrous dimethyl sulfoxide solvent, mix well, stir at 67 °C for 19 h, after the reaction is completed, cool to room temperature, pour the reaction solution into 380 mL of acetone, precipitate, filter, wash 4 times with ethanol, and vacuum dry at 68 °C for 26 h to obtain grafted modified cellulose; (6) 2.57 g of grafted modified cellulose was dispersed in 48 mL of isopropanol and stirred to obtain a suspension. 6.7 mL of 30% sodium hydroxide aqueous solution was added dropwise and stirred at 38 °C for 2 h for alkalization. Then, 3.57 g of sodium chloroacetate was added and stirred at 72 °C for 4 h. After the reaction was completed, the mixture was cooled to room temperature and the pH was adjusted to 8 with 1 mol / L dilute hydrochloric acid. The reactants were poured into 240 mL of 80% ethanol aqueous solution and stirred to precipitate the product. The product was filtered and washed until no chloride ions were found in the filtrate. The product was vacuum dried at 68 °C for 23 h, pulverized, and passed through a 120-mesh sieve to obtain high-temperature resistant polyanionic cellulose.

[0029] Comparative Example 1 The main difference between this comparative example and Example 4 is that the 2-acrylamide-2-methylpropanesulfonic acid functional chain segment containing sulfonic acid groups was not introduced, and only the rigid naphthalene core structure was retained.

[0030] The specific preparation method is as follows: without performing step (3) of Example 4, the 2,7-bis(4-aminophenoxy)naphthalene prepared in step (2) of Example 4 and the epoxy cellulose prepared in step (4) of Example 4 are reacted according to the conditions of step (5) of Example 4. The subsequent carboxymethylation step is exactly the same as step (6) of Example 4, and a polyanionic cellulose containing only naphthalene core and carboxymethyl is obtained.

[0031] Comparative Example 2 The main difference between this comparative example and Example 4 is that a rigid naphthalene core structure is not introduced; instead, carboxymethyl and sulfonic acid groups are introduced simultaneously onto the cellulose backbone.

[0032] The specific preparation method is as follows: (1) Epoxy cellulose was prepared according to step (4) of Example 4; (2) 2.57 g of epoxy cellulose was dispersed in 48 mL of isopropanol and stirred to obtain a suspension. 6.7 mL of 30% sodium hydroxide aqueous solution was added dropwise and alkalized by stirring at 38 °C for 2 h. Then, 3.57 g of sodium chloroacetate and 1.2 g of sodium 3-chloro-2-hydroxypropanesulfonate were added and stirred at 72 °C for 4 h. After the reaction was completed, the mixture was cooled to room temperature and the pH was adjusted to 8 with 1 mol / L dilute hydrochloric acid. The reactants were poured into 240 mL of 80% ethanol aqueous solution and stirred to precipitate the product. The product was filtered and washed until there were no chloride ions in the filtrate. The product was vacuum dried at 68 °C for 23 h, pulverized, and passed through a 120-mesh sieve to obtain polyanionic cellulose containing only sulfonic acid groups and carboxymethyl groups.

[0033] Performance testing The polyanionic celluloses prepared in Examples 1-4 and Comparative Examples 1-2 were subjected to performance tests.

[0034] Test method: Weigh 1g of the polyanionic cellulose samples prepared in Examples 1-4 and Comparative Examples 1-2 respectively and add them to 5mL of anhydrous ethanol. Stir until completely wetted into a paste. Then, while stirring at 800rpm, slowly add 99g of saturated brine and continue stirring for 30min. Allow to hydrate in a 25℃ water bath for 4h to obtain a homogeneous 1% mass fraction test slurry. At 25℃, use a rheometer to measure the slurry over 170s. -1The test was conducted at a shear rate of [value missing]. Each sample was tested in parallel three times, and the average value was taken. After the initial viscosity test, all the remaining slurry was transferred to a high-temperature aging tank and hot-rolled in a roller furnace at 180℃ for 16 hours. Then, it was removed and cooled to room temperature, and the viscosity of the solution was measured again. The viscosity retention rate was calculated using the formula: Viscosity retention rate = (viscosity after aging / viscosity before aging) × 100%. A 1% sample slurry was prepared again using the same method, hydrated for 4 hours, and stirred evenly. The slurry was then poured into a 500mL high-temperature and high-pressure filtration loss analyzer slurry cup, with the liquid level at the mark. The API filter paper and receiving device were assembled, and the slurry cup was placed in the filtration loss analyzer. The temperature was heated to 180℃ according to the operating procedure, and a pressure of 3.5MPa was applied. Filtration was started under pressure and timed for 30 minutes. Then, the receiving tube was removed, and the volume of the collected filtrate was read. This volume value is the API filtration loss. Each sample was tested in parallel twice. The test results are shown in Table 1.

[0035] Table 1: Performance Tests

[0036] As can be seen from Table 1, the polyanionic cellulose prepared in Examples 1-4 has good high temperature resistance, salt resistance and filtration loss reduction effect.

[0037] The comparison shows that Comparative Example 1, without the introduction of the 2-acrylamido-2-methylpropanesulfonic acid functional segment containing sulfonic acid groups, only retains the rigid naphthalene core structure. In the high ionic strength environment of saturated salt water, it mainly relies on the electrostatic repulsion and hydration layer provided by the carboxymethyl group to increase viscosity. The hydration layer of the carboxymethyl group has weak salt resistance and is easily compressed and destroyed by high concentrations of salt ions, resulting in a decrease in initial viscosity. At high temperatures, although the rigid structure of the naphthalene core can inhibit molecular chain breakage to some extent, the lack of steric hindrance protection from the sulfonic acid group means that the molecular chains will still undergo local dehydration aggregation and thermal degradation, leading to viscosity loss. Therefore, the performance of Comparative Example 1 decreased. Comparative Example 2 did not introduce a rigid naphthalene core structure, but only introduced carboxymethyl and sulfonic acid groups on the cellulose skeleton. The introduction of sulfonic acid groups improved the short-term salt resistance and initial thickening effect of the product. However, due to the high flexibility of the cellulose molecular chain itself, it undergoes violent thermal motion at high temperatures. Lacking the support and protection of the rigid naphthalene core, the molecular chain is prone to chain breakage, hydrolysis and thermal oxidative decomposition. It cannot maintain long-term high-temperature stability and cannot provide sufficient viscosity support for filter cake formation. The filter cake structure is loose and has high permeability, so the performance of Comparative Example 2 decreased.

[0038] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0039] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

[0040] Those skilled in the art should understand that the above descriptions are merely several specific embodiments of the present invention, and not all embodiments.

Claims

1. A method for preparing high-temperature resistant polyanionic cellulose, characterized in that, Includes the following steps: (1) Preparation of 2,7-bis(4-nitrophenoxy)naphthalene: 2,7-bis(4-nitrophenoxy)naphthalene is obtained by reacting p-nitrochlorobenzene and 2,7-dihydroxynaphthalene; (2) Preparation of 2,7-bis(4-aminophenoxy)naphthalene: The nitro group of 2,7-bis(4-nitrophenoxy)naphthalene was reduced to amino group to obtain 2,7-bis(4-aminophenoxy)naphthalene; (3) Preparation of intermediate 1: 2,7-bis(4-aminophenoxy)naphthalene and 2-acrylamide-2-methylpropanesulfonic acid undergo Michael addition reaction in the presence of hydroquinone inhibitor in an ice-water bath to obtain intermediate 1 retaining a primary amino group; (4) Preparation of epoxy cellulose: cellulose reacts with glycidyl methacrylate to obtain epoxy cellulose; (5) Preparation of grafted modified cellulose: Intermediate 1 reacts with epoxy cellulose to obtain grafted modified cellulose; (6) Preparation of high temperature resistant polyanionic cellulose: Grafted modified cellulose is etherified with sodium chloroacetate to obtain high temperature resistant polyanionic cellulose.

2. The method for preparing high-temperature resistant polyanionic cellulose according to claim 1, characterized in that, In step (1), the preparation method of 2,7-bis(4-nitrophenoxy)naphthalene is as follows: 10.4-10.5g of 2,7-dihydroxynaphthalene, 19.8-19.9g of p-nitrochlorobenzene, 17.3-17.4g of anhydrous potassium carbonate, 15-17mL of toluene, and 150-160mL of N,N-dimethylformamide are added to a reactor and stirred and mixed. After reacting at 140-150℃ for 9-12h, the temperature is raised to 150-160℃ for 1-1.5h. After the reaction is completed, the mixture is filtered while hot. After the filtrate has stood for 10-12h, the precipitate crystallized in the filtrate is filtered out. The precipitate is washed with water 3-4 times and then dried in an oven at 55-65℃ to obtain 2,7-bis(4-nitrophenoxy)naphthalene.

3. The method for preparing high-temperature resistant polyanionic cellulose according to claim 1, characterized in that, In step (2), the preparation method of 2,7-bis(4-aminophenoxy)naphthalene is as follows: under nitrogen protection, 15-16g of 2,7-bis(4-nitrophenoxy)naphthalene, 2.25-2.35g of ferric chloride, 7.5-7.6g of activated carbon, and 115-125mL of ethylene glycol methyl ether are added to the reactor and mixed evenly. The mixture is reacted at 100-110℃ for 8-12h. After the reaction is completed, the mixture is filtered while hot. After the filtrate is cooled to room temperature, it is rotary evaporated at 75-85℃. Then, the concentrated solution is poured into 300-350mL of deionized water to precipitate the precipitate. The precipitate is filtered, washed, and dried to obtain 2,7-bis(4-aminophenoxy)naphthalene.

4. The method for preparing high-temperature resistant polyanionic cellulose according to claim 1, characterized in that, In step (3), the preparation method of intermediate 1 is as follows: under nitrogen gas protection and 0-5℃ ice-water bath, 40-45 mL of deionized water and 40-45 mL of anhydrous ethanol are added to the reactor and mixed to obtain a solvent. Then, 10-10.1 g of 2,7-bis(4-aminophenoxy)naphthalene and 0.02-0.022 g of hydroquinone are added to it and mixed evenly to form a suspension. At the same time, 4.1-4.2 g of 2-acrylamide-2-methylpropanesulfonic acid is dissolved in 15-20 mL of deionized water to obtain a sulfonic acid aqueous solution. The sulfonic acid aqueous solution is added dropwise to the suspension under stirring for 4-6 h. After the addition is completed, the reaction is continued to be stirred for 12-16 h while maintaining the 0-5℃ ice-water bath. After the reaction is completed, rotary evaporation is carried out at 25-35℃. Then, the concentrated liquid is poured into 200-220 mL of acetone to precipitate the precipitate. The precipitate is filtered, washed and dried to obtain intermediate 1.

5. The method for preparing high-temperature resistant polyanionic cellulose according to claim 1, characterized in that, In step (4), the preparation method of epoxy cellulose is as follows: under nitrogen protection, 80-82g of 1-butyl-3-methylimidazolium chloride and 4-4.1g of microcrystalline cellulose are added to the reactor and mixed and dissolved at 25-35℃. Then, 0.1-0.11g of potassium persulfate is added and stirred for 30-40min. Then, 3.51-3.55g of glycidyl methacrylate is added dropwise. After the addition is complete, the reaction is stirred for 3-4h. After the reaction is completed, the reaction solution is poured into 300-400mL of anhydrous ethanol to precipitate. The solid is collected by suction filtration and washed until there are no chloride ions in the filtrate. The solid is then vacuum dried at 55-65℃ for 24-28h to obtain epoxy cellulose.

6. The method for preparing high-temperature resistant polyanionic cellulose according to claim 1, characterized in that, In step (5), the grafted modified cellulose is prepared as follows: 3-3.1g of epoxy cellulose and 4.4-4.5g of intermediate 1 are added to 70-80mL of anhydrous dimethyl sulfoxide solvent, mixed evenly, and stirred at 60-70℃ for 16-20h. After the reaction is completed, the mixture is cooled to room temperature, and the reaction solution is poured into 300-400mL of acetone to precipitate. The precipitate is filtered, washed with ethanol 3-4 times, and vacuum dried at 60-70℃ for 24-26h to obtain grafted modified cellulose.

7. The method for preparing high-temperature resistant polyanionic cellulose according to claim 1, characterized in that, In step (6), the preparation method of high-temperature resistant polyanionic cellulose is as follows: 2.5-2.6g of grafted modified cellulose is dispersed in 40-50mL of isopropanol, stirred to obtain a suspension, and 6-7mL of 30% sodium hydroxide aqueous solution is added dropwise. The mixture is stirred at 35-40℃ for 1-2h for alkalization. Then, 3.5-3.6g of sodium chloroacetate is added, and the mixture is stirred at 65-75℃ for 3-4h. After the reaction is completed, the mixture is cooled to room temperature, and the pH is adjusted to 7-8 with 1mol / L dilute hydrochloric acid. The reactants are poured into 200-250mL of 80% ethanol aqueous solution, stirred to precipitate the product, filtered, washed until no chloride ions are present in the filtrate, vacuum dried at 60-70℃ for 20-24h, pulverized, and passed through a 100-120 mesh sieve to obtain high-temperature resistant polyanionic cellulose.

8. A high-temperature resistant polyanionic cellulose, characterized in that, It is prepared by the preparation method described in any one of claims 1-7.

Images