Anti-sloughing polymer material and preparation method thereof

Abstract

The invention discloses an anti-sloughing polymer material and a preparation method thereof, and belongs to the technical field of well drilling protection medicament preparation. Mixing a polyhydroxy branched monomer, polybasic anhydride, an organic solvent, an inorganic nano blocking agent and a catalyst, reacting, and neutralizing to obtain a hydroxyl-terminated hyperbranched polyester coating emulsion; mixing and reacting an unsaturated isocyanate compound, acrylate, dopamine, deionized water, a composite dispersant and an initiator to obtain an isocyanate group-containing polyacrylate coating solution; and mixing the hydroxyl-terminated hyperbranched polyester coating emulsion, the isocyanate group-containing polyacrylate coating liquid and an organic tin catalyst, and reacting to obtain the polymer material. According to the invention, a hydroxyl-terminated hyperbranched polyester coating emulsion and an isocyanate group-containing polyacrylate coating liquid are mixed and reacted to obtain a polymer material with a good anti-sloughing effect.

Description

Technical Field

[0001] This invention belongs to the field of drilling protection agent preparation technology, specifically relating to a collapse-preventing polymer material and its preparation method. Background Technology

[0002] In oil and gas exploration and development, solid mineral deposit exploration, and basic engineering construction, formation stability is one of the key factors ensuring the safety and efficiency of these production activities. Shale is a common formation type, mainly composed of clay minerals. Its unique physicochemical properties present numerous challenges during drilling. In particular, the hydration and swelling phenomenon in shale often leads to a decrease in wellbore strength, resulting in wellbore collapse, stuck pipe, and other complex downhole situations, reducing drilling speed, causing significant economic losses, and even major safety problems. The reasons for wellbore instability and collapse in shale include: under the influence of pressure difference, chemical potential difference, and formation capillary forces between drilling fluid and pore fluid, drilling fluid filtrate intrudes into the shale formation, interacting with the clay. The clay minerals in the formation absorb water and swell, affecting wellbore stability; microfractures and micropores in the shale formation expand after absorbing water, allowing drilling fluid filtrate to enter the formation through the micro-nanoscale channels of the shale, causing clay hydration. This formation hydration and swelling affects wellbore stability.

[0003] Currently, methods for wellbore stabilization during drilling are mainly designed from two aspects: physical plugging and chemical inhibition. Chemical inhibition mainly works by inhibiting the intrusion and penetration of drilling fluid filtrate into the shale wellbore fissures and increasing the bonding force between clay mineral particles in the wellbore. This effectively inhibits the problem of clay minerals easily hydrating and swelling, thereby achieving wellbore stability. Patent CN118813217A discloses a drilling fluid anti-collapse agent and its preparation method. This invention obtains the drilling fluid anti-collapse agent by adding boron-containing quaternary ammonium salt modified phenolic resin, ester-containing epoxy resin modified polyacrylamide, natural asphalt, and calcium chloride into a reactor and stirring. Quaternary ammonium salts form a protective film on the rock surface, preventing formation collapse due to external forces and improving the anti-collapse effect; the three-dimensional network structure formed by boron-oxygen bonds is not easily destroyed at high temperatures, improving high-temperature resistance; the network structure formed by cyanuric chloride remains stable at high temperatures, improving the adhesion and high-temperature resistance of the anti-collapse agent; the hydroxyl and carboxyl groups generated after ester hydrolysis can cross-link the polymer, thereby improving the anti-collapse effect; epoxy resin can increase the viscosity of the anti-collapse agent, helping to form a denser mud cake, improving the sealing effect of the anti-collapse agent, and also helping to stabilize the wellbore, thus improving the anti-collapse effect.

[0004] Physical plugging primarily achieves good plugging and stabilization effects through inorganic nanomaterials. Shale contains numerous microcracks and micropores, and inorganic nanomaterials, with their high surface area and small size, easily penetrate these microcracks and micropores, effectively plugging the shale clay before it undergoes hydration and expansion, thus stabilizing the wellbore. However, due to the extremely high surface energy of inorganic nanomaterials, they are prone to aggregation, leading to increased size and the formation of aggregates that are difficult to fully fill the wellbore gaps. Patent CN116063998A discloses an aluminum-based plugging and anti-collapse agent, its preparation method, and its application. This invention provides an aluminum-based plugging and anti-collapse agent using aluminum humate as the active ingredient, utilizing Al... 3+ Upon pH change, Al(OH)3 precipitate is generated, enabling effective intelligent plugging of micro-fractures of different sizes. This overturns the traditional plugging method where the particle size of the plugging agent must strictly match the fracture size, freeing water-based drilling fluids containing it from the constraints of complex formations. It is a high-performance self-matching plugging and anti-collapse agent. This invention achieves plugging through chemical reaction to synthesize particle precipitates, but it does not directly and effectively solve the problems inherent in inorganic nanomaterials themselves.

[0005] Therefore, it is of great significance to directly address the aggregation of inorganic nanomaterials and thus achieve stable protection of the well wall to prevent collapse. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention utilizes a mixture of hydroxyl-terminated hyperbranched polyester coating emulsion and isocyanate-containing polyacrylate coating liquid to obtain a polymer material with excellent anti-collapse properties, thereby solving the technical problems mentioned in the background art. Specifically, the technical solution of this invention includes the following: One objective of this invention is to provide a method for preparing an anti-collapse polymer material, the method comprising the following steps: A mixture of polyhydroxy branched monomers, polybasic acid anhydrides, organic solvents, inorganic nano-blocking agents and catalysts was heated to 130℃~150℃ for 4h~5h, then cooled to 60℃~70℃ and neutralized with alkali to obtain a hydroxyl-terminated hyperbranched polyester coating emulsion. Unsaturated isocyanate compound, acrylate, dopamine, deionized water, composite dispersant and initiator are mixed in a weight ratio of 1~2:4~6:0.01~0.02:9~15:0.1~0.2:0.02~0.03 and heated to 75℃~80℃ for 2.5h~3.5h to obtain an isocyanate-containing polyacrylate coated solution; The polymer material is obtained by mixing a hydroxyl-terminated hyperbranched polyester coating emulsion, an isocyanate-containing polyacrylate coating liquid, and an organotin catalyst in a weight ratio of 1:0.1~0.4:0.005 and heating to 60℃~70℃ for 2 hours.

[0007] Furthermore, the polyhydroxy branched monomer includes 2,2-dihydroxymethylbutyric acid.

[0008] Furthermore, the polyacid anhydride includes 4,4'-biphenyl dianhydride.

[0009] Furthermore, the organic solvent includes N,N-dimethylformamide or N,N-dimethylacetamide.

[0010] Furthermore, the inorganic nano-blocking agent includes nano-silica.

[0011] Furthermore, the particle size of the nano-silica is 30 nm.

[0012] Furthermore, the catalyst includes p-toluenesulfonic acid.

[0013] Furthermore, the molar ratio of the polyhydroxy branched monomer to the polybasic acid anhydride is 4~5.2:1, the amount of the organic solvent used is 3 to 4 times the total mass of the polyhydroxy branched monomer and the polybasic acid anhydride, the amount of the inorganic nano-blocking agent used is 2% to 5% of the total mass of the polyhydroxy branched monomer and the polybasic acid anhydride, and the amount of the catalyst used is 0.2% to 0.4% of the total mass of the polyhydroxy branched monomer and the polybasic acid anhydride.

[0014] Furthermore, the alkali used for neutralization includes a sodium hydroxide solution with a molar concentration of 0.1 mol / L.

[0015] Furthermore, the unsaturated isocyanate compound includes 3-isopropyl-dimethylbenzyl isocyanate.

[0016] Furthermore, the acrylate is composed of methyl methacrylate, lauryl methacrylate, and octadecyl methacrylate in a weight ratio of 3:1:1.

[0017] Furthermore, the composite dispersant is composed of sodium dodecylbenzenesulfonate and emulsifier OP-10 in a weight ratio of 1:0.5.

[0018] Furthermore, the organotin catalyst comprises dibutyltin dilaurate.

[0019] A second objective of this invention is to provide a polymer material that prevents collapse.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention uses nano-silica as a physical plugging agent. It utilizes the low viscosity of hyperbranched polyester to modify the agglomeration of nano-silica, resulting in a hydroxyl-terminated hyperbranched polyester-coated emulsion. This improves the dispersion uniformity of the nanoparticles, thus facilitating their entry into shale fissures for plugging. However, due to its low viscosity, it cannot firmly adhere to the shale surface during the plugging process, resulting in poor effectiveness in preventing the hydration and dispersion of shale particles, thereby affecting the anti-collapse effect. Therefore, based on the principles of molecular bionics, this invention utilizes the ability of dopamine to oxidize and self-polymerize in an alkaline environment to form an adhesive polydopamine structure. This structure is then polymerized to generate a polyacrylate structure with isocyanate groups, which encapsulates the dopamine, resulting in an isocyanate-containing polyacrylate coating fluid. In the high-temperature, high-pressure alkaline environment of drilling, dopamine is released and undergoes oxidative self-polymerization, improving the binding force between shale mineral particles and effectively inhibiting the problem of easy hydration and swelling of clay minerals. Finally, the hydroxyl-terminated hyperbranched polyester coating emulsion and the isocyanate-containing polyacrylate coating fluid are mixed and reacted. Through the dual synergistic sealing effect of physical and chemical processes, the performance of the prepared polymer material is improved when used for drilling anti-collapse protection, thereby achieving wellbore pressure stability. Detailed Implementation

[0021] The technical solution of the present invention will be clearly and completely described below through embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. 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.

[0022] Unless otherwise stated, all raw materials and reagents used in this invention are commercially available or can be prepared by known methods.

[0023] Example 1 A method for preparing a collapse-resistant polymer material, specifically including the following preparation process: 0.4 mol of 2,2-dihydroxymethylbutyric acid and 0.1 mol of 4,4'-biphenyl dianhydride were weighed and added to the reactor. Then, N,N-dimethylformamide, weighing three times the total mass of 2,2-dihydroxymethylbutyric acid and 4,4'-biphenyl dianhydride in the reactor, was added to the reactor and stirred until completely dissolved. Next, 2% of the total mass of 2,2-dihydroxymethylbutyric acid and 4,4'-biphenyl dianhydride in the reactor, consisting of nano-silica (30 nm particle size), and 0.2% of the total mass of p-toluenesulfonic acid were weighed and added to the reactor. The mixture was first stirred at 500 rpm for 30 minutes, then dispersed using 400 W of ultrasonic power for 20 minutes. Finally, the reactor was shut off, and nitrogen gas was introduced to replace the air inside the reactor. The rotation speed in the reactor was adjusted to 200 r / min, and then the reactor was heated to 130°C by an electric heating system at a heating rate of 0.5°C / min. The reactor was stirred and reacted at this temperature for 4 hours. After the reaction, the temperature was lowered to 60℃ and maintained at this temperature. The pH of the mixture inside the reactor was adjusted using a 0.1 mol / L sodium hydroxide solution until neutral. The stirring speed was then increased to 600 r / min and emulsification continued for 30 min. Finally, the mixture was allowed to cool naturally to room temperature to obtain a hydroxyl-terminated hyperbranched polyester-coated emulsion. 10 parts by weight of 3-isopropyl-dimethylbenzyl isocyanate, 40 parts by weight of acrylate (obtained by mixing methyl methacrylate, lauryl methacrylate, and octadecyl methacrylate in a weight ratio of 60:20:20), 0.1 parts by weight of dopamine, 90 parts by weight of deionized water, 1 part by weight of a composite dispersant (composed of sodium dodecylbenzenesulfonate and emulsifier OP-10 in a weight ratio of 10:5), and 0.2 parts by weight of dibutyltin dilaurate were mixed together, and then... The mixture was placed in a high-speed homogenizer and emulsified at a speed of 8000 r / min until homogeneous. Then, it was transferred to a reactor, the reactor was closed, and nitrogen gas was introduced to replace the air inside the reactor. The speed of the reactor was controlled at 250 r / min, and the reactor was heated to 75°C by an electric heating system. The reaction was carried out at this temperature for 3.5 h. After the reaction, the temperature was lowered to 40°C and the material was discharged. Then, it was allowed to cool naturally to room temperature to obtain a polyacrylate coating liquid containing isocyanate groups. One part by weight of the hydroxyl-terminated hyperbranched polyester coating emulsion, 0.1 part by weight of the polyacrylate coating liquid containing isocyanate groups, and 0.005 part by weight of the organotin catalyst were weighed and mixed together. Nitrogen gas was used as a protective gas, and the stirring speed was set to 300 r / min. The mixture was then heated to 60°C and stirred for 2 h. The temperature was then lowered to 40°C and the material was discharged. Finally, it was allowed to cool naturally to room temperature to obtain the polymer material.

[0024] Example 2 A method for preparing a collapse-resistant polymer material, specifically including the following preparation process: 0.44 mol of 2,2-dihydroxymethylbutyric acid and 0.1 mol of 4,4'-biphenyl dianhydride were weighed and added to the reactor. Three times the total mass of 2,2-dihydroxymethylbutyric acid and 4,4'-biphenyl dianhydride in the reactor were then added to the reactor and stirred until completely dissolved. Next, 3% of the total mass of 2,2-dihydroxymethylbutyric acid and 4,4'-biphenyl dianhydride in the reactor, nano-silica (30 nm particle size) and 0.2% of the total mass of 2,2-dihydroxymethylbutyric acid and 4,4'-biphenyl dianhydride in the reactor were weighed and added to the reactor. The mixture was first stirred at 500 rpm for 30 min, then dispersed using 400 W of ultrasonic power for 20 min. Finally, the reactor was shut off, and nitrogen gas was introduced to replace the air inside the reactor. The rotation speed in the reactor was adjusted to 200 r / min, and then the reactor was heated to 130°C by an electric heating system at a heating rate of 0.5°C / min. The reaction was stirred at this temperature for 4.5 h. After the reaction, the temperature was lowered to 60℃ and maintained at this temperature. The pH of the mixture inside the reactor was adjusted using a 0.1 mol / L sodium hydroxide solution until neutral. The stirring speed was then increased to 600 r / min, and emulsification was continued for 30 min. Finally, the mixture was allowed to cool naturally to room temperature to obtain a hydroxyl-terminated hyperbranched polyester-coated emulsion. 14 parts by weight of 3-isopropyl-dimethylbenzyl isocyanate, 50 parts by weight of acrylate (obtained by mixing methyl methacrylate, lauryl methacrylate, and octadecyl methacrylate in a weight ratio of 60:20:20), 0.15 parts by weight of dopamine, 110 parts by weight of deionized water, 1.5 parts by weight of a composite dispersant (composed of sodium dodecylbenzenesulfonate and emulsifier OP-10 in a weight ratio of 10:5), and 0.2 parts by weight of dibutyltin dilaurate were mixed together. First, the mixture was placed in a high-speed homogenizer and emulsified at a speed of 8000 r / min until homogeneous. Then, it was transferred to a reactor, the reactor was closed, and nitrogen gas was introduced to replace the air inside the reactor. The speed of the reactor was controlled at 250 r / min, and the reactor was heated to 75°C by an electric heating system. The reaction was carried out at this temperature for 3 hours. After the reaction, the temperature was lowered to 40°C and the mixture was discharged. Then, it was allowed to cool naturally to room temperature to obtain a polyacrylate coating liquid containing isocyanate groups. One part by weight of the hydroxyl-terminated hyperbranched polyester coating emulsion, 0.2 parts by weight of the polyacrylate coating liquid containing isocyanate groups, and 0.005 parts by weight of the organotin catalyst were weighed and mixed together. Nitrogen gas was used as a protective gas, and the stirring speed was set to 300 r / min. The mixture was then heated to 65°C and stirred for 2 hours. The temperature was then lowered to 40°C and the mixture was discharged. Finally, it was allowed to cool naturally to room temperature to obtain the polymer material.

[0025] Example 3 A method for preparing a collapse-resistant polymer material, specifically including the following preparation process: 0.48 mol of 2,2-dihydroxymethylbutyric acid and 0.1 mol of 4,4'-biphenyl dianhydride were weighed and added to the reactor. N,N-dimethylacetamide, weighed at 3.5 times the total mass of 2,2-dihydroxymethylbutyric acid and 4,4'-biphenyl dianhydride in the reactor, was added to the reactor and stirred until completely dissolved. Then, 4% of the total mass of 2,2-dihydroxymethylbutyric acid and 4,4'-biphenyl dianhydride in the reactor, nano-silica (30 nm particle size) and 0.3% of the total mass of 2,2-dihydroxymethylbutyric acid and 4,4'-biphenyl dianhydride in the reactor were weighed and added to the reactor. The mixture was first stirred at 500 rpm for 30 min, then dispersed using 400 W of ultrasonic power for 20 min. The reactor was then closed, and nitrogen was introduced to replace the air inside the reactor. The rotation speed in the reactor was adjusted to 200 r / min, and then the reactor was heated to 140°C by an electric heating system at a heating rate of 0.5°C / min. The reaction was stirred at this temperature for 4.5 h. After the reaction, the temperature was lowered to 70℃ and maintained at this temperature. The pH of the mixture inside the reactor was adjusted using a 0.1 mol / L sodium hydroxide solution until neutral. The stirring speed was then increased to 600 r / min, and emulsification was continued for 30 min. Finally, the mixture was allowed to cool naturally to room temperature to obtain a hydroxyl-terminated hyperbranched polyester-coated emulsion. Eight parts by weight of 3-isopropyl-dimethylbenzyl isocyanate, 55 parts by weight of acrylate (obtained by mixing methyl methacrylate, lauryl methacrylate, and octadecyl methacrylate in a weight ratio of 60:20:20), 0.2 parts by weight of dopamine, 130 parts by weight of deionized water, 1.5 parts by weight of a composite dispersant (composed of sodium dodecylbenzenesulfonate and emulsifier OP-10 in a weight ratio of 10:5), and 0.3 parts by weight of dibutyltin dilaurate were mixed together, and then... The mixture was placed in a high-speed homogenizer and emulsified at a speed of 8000 r / min until homogeneous. It was then transferred to a reactor, the reactor was closed, and nitrogen gas was introduced to replace the air inside. The reactor speed was controlled at 250 r / min, and the reactor was heated to 75°C using an electric heating system. The reaction was carried out at this temperature for 2.5 hours. After the reaction, the temperature was lowered to 40°C and the mixture was discharged. The mixture was then allowed to cool naturally to room temperature to obtain an isocyanate-containing polyacrylate coating liquid. One part by weight of the hydroxyl-terminated hyperbranched polyester coating emulsion, 0.3 parts by weight of the isocyanate-containing polyacrylate coating liquid, and 0.005 parts by weight of the organotin catalyst were weighed and mixed together. Nitrogen gas was used as a protective gas, and the stirring speed was set to 300 r / min. The mixture was then heated to 70°C and stirred for 2 hours. The temperature was then lowered to 40°C and the mixture was discharged. Finally, the mixture was allowed to cool naturally to room temperature to obtain the polymer material.

[0026] Example 4 A method for preparing a collapse-resistant polymer material, specifically including the following preparation process: 0.52 mol of 2,2-dihydroxymethylbutyric acid and 0.1 mol of 4,4'-biphenyl dianhydride were weighed and added to the reactor. Four times the total mass of 2,2-dihydroxymethylbutyric acid and 4,4'-biphenyl dianhydride in the reactor were then added to the reactor and stirred until completely dissolved. Next, 5% of the total mass of 2,2-dihydroxymethylbutyric acid and 4,4'-biphenyl dianhydride in the reactor, nano-silica (30 nm particle size), and 0.4% of the total mass of 2,2-dihydroxymethylbutyric acid and 4,4'-biphenyl dianhydride in the reactor were weighed and added to the reactor. The mixture was first stirred at 500 rpm for 30 min, then dispersed using 400 W of ultrasonic power for 20 min. Finally, the reactor was closed, and nitrogen gas was introduced to replace the air inside the reactor. The rotation speed in the reactor was adjusted to 200 r / min, and then the reactor was heated to 150°C by an electric heating system at a heating rate of 0.5°C / min. The reactor was stirred and reacted at this temperature for 5 hours. After the reaction, the temperature was lowered to 70℃ and maintained at this temperature. The pH of the mixture inside the reactor was adjusted using a 0.1 mol / L sodium hydroxide solution until neutral. The stirring speed was then increased to 600 r / min and emulsification continued for 30 min. Finally, the mixture was allowed to cool naturally to room temperature to obtain a hydroxyl-terminated hyperbranched polyester-coated emulsion. 20 parts by weight of 3-isopropyl-dimethylbenzyl isocyanate, 60 parts by weight of acrylate (obtained by mixing methyl methacrylate, lauryl methacrylate, and octadecyl methacrylate in a weight ratio of 60:20:20), 0.2 parts by weight of dopamine, 150 parts by weight of deionized water, 2 parts by weight of composite dispersant (composed of sodium dodecylbenzenesulfonate and emulsifier OP-10 in a weight ratio of 10:5), and 0.3 parts by weight of dibutyltin dilaurate were mixed together, and then... The mixture was placed in a high-speed homogenizer and emulsified at a speed of 8000 r / min until homogeneous. It was then transferred to a reactor, the reactor was closed, and nitrogen gas was introduced to replace the air inside. The reactor speed was controlled at 250 r / min, and the reactor was heated to 75°C using an electric heating system. The reaction was carried out at this temperature for 2.5 hours. After the reaction, the temperature was lowered to 40°C and the mixture was discharged. The mixture was then allowed to cool naturally to room temperature to obtain an isocyanate-containing polyacrylate coating liquid. One part by weight of the hydroxyl-terminated hyperbranched polyester coating emulsion, 0.4 parts by weight of the isocyanate-containing polyacrylate coating liquid, and 0.005 parts by weight of the organotin catalyst were weighed and mixed together. Nitrogen gas was used as a protective gas, and the stirring speed was set to 300 r / min. The mixture was then heated to 70°C and stirred for 2 hours. The temperature was then lowered to 40°C and the mixture was discharged. Finally, the mixture was allowed to cool naturally to room temperature to obtain the polymer material.

[0027] Comparative Example 1 A method for preparing a collapse-resistant polymer material, specifically including the following preparation process: 0.52 mol of trimethylolpropane and 0.1 mol of 4,4'-biphenyl dianhydride were weighed and added to the reactor. N,N-dimethylacetamide, weighed at 4 times the total mass of trimethylolpropane and 4,4'-biphenyl dianhydride in the reactor, was added to the reactor and mixed until completely dissolved. Then, 5% of the total mass of trimethylolpropane and 4,4'-biphenyl dianhydride in the reactor, nano-silica (particle size 30 nm), and 0.4% of the total mass of trimethylolpropane and 4,4'-biphenyl dianhydride in the reactor, p-toluenesulfonic acid were weighed and added to the reactor. The mixture was stirred at 500 rpm for 30 min, then dispersed by ultrasonic power at 400 W for 20 min. The reactor was then closed and nitrogen was introduced to replace the air inside the reactor. The rotation speed in the reactor was adjusted to 200 r / min, and then the reactor was heated to 150℃ using an electric heating system at a heating rate of 0.5℃ / min. The reaction was carried out at this temperature with stirring for 5 hours. After the reaction was completed, the mixture was allowed to cool naturally to room temperature to obtain a hydroxyl-terminated hyperbranched polyester coating solution. The remaining preparation process is the same as in Example 4.

[0028] Comparative Example 2 A method for preparing a collapse-resistant polymer material, specifically including the following preparation process: 0.52 mol of 2,2-dimethylolbutyric acid and 0.1 mol of maleic anhydride were weighed and added to the reactor. Four times the total mass of 2,2-dimethylolbutyric acid and maleic anhydride in the reactor were then added and stirred until completely dissolved. Next, 5% of the total mass of 2,2-dimethylolbutyric acid and maleic anhydride in the reactor, consisting of nano-silica (30 nm particle size), and 0.4% of the total mass of 2,2-dimethylolbutyric acid and maleic anhydride in the reactor, were weighed and added to the reactor. The mixture was first stirred at 500 rpm for 30 min, then dispersed using 400 W of ultrasonic power for 20 min. The reactor was then closed, and nitrogen was introduced to purge the air from the reactor. The stirring speed was adjusted to 200 rpm, and the reactor was heated to 150 °C at a rate of 0.5 °C / min using an electric heating system. The reaction was then carried out at this temperature with stirring for 5 h. After the reaction was completed, the temperature was lowered to 70℃ and kept at this temperature. In this temperature environment, the pH of the mixture inside the reactor was adjusted with a sodium hydroxide solution with a molar concentration of 0.1 mol / L until it reached neutral. Then, the stirring speed was increased to 600 r / min and the emulsification was continued for 30 min. Finally, it was naturally cooled to room temperature to obtain the hydroxyl-terminated hyperbranched polyester coating emulsion. The remaining preparation process is the same as in Example 4.

[0029] Comparative Example 3 A method for preparing a collapse-resistant polymer material, specifically including the following preparation process: 0.52 mol of 2,2-dihydroxymethylbutyric acid and 0.1 mol of 4,4'-biphenyl dianhydride were weighed and added to the reactor. Four times the total mass of 2,2-dihydroxymethylbutyric acid and 4,4'-biphenyl dianhydride in the reactor were then added to the reactor and stirred until completely dissolved. Next, 5% of the total mass of 2,2-dihydroxymethylbutyric acid and 4,4'-biphenyl dianhydride in the reactor, containing nano-calcium carbonate (30 nm particle size), and 0.4% of the total mass of 2,2-dihydroxymethylbutyric acid and 4,4'-biphenyl dianhydride, containing p-toluenesulfonic acid, were weighed and added to the reactor. The mixture was first stirred at 500 rpm for 30 min, then dispersed using 400 W of ultrasonic power for 20 min. Finally, the reactor was shut off, and nitrogen gas was introduced to replace the air inside the reactor. The reactor rotation speed was adjusted to 200 r / min, and then the reactor was heated to 150°C via an electric heating system at a heating rate of 0.5°C / min. The reaction was carried out at this temperature with stirring for 5 hours. After the reaction was completed, the temperature was lowered to 70°C and maintained at this temperature. At this temperature, the pH of the mixture inside the reactor was adjusted with a 0.1 mol / L sodium hydroxide solution until it reached neutral. Then, the rotation speed was increased to 600 r / min and stirring and emulsification were continued for 30 minutes. Finally, the mixture was allowed to cool naturally to room temperature to obtain a hydroxyl-terminated hyperbranched polyester-coated emulsion. The remaining preparation process is the same as in Example 4.

[0030] Comparative Example 4 A method for preparing a collapse-resistant polymer material, specifically including the following preparation process: 0.52 mol of 2,2-dihydroxymethylbutyric acid and 0.1 mol of 4,4'-biphenyl dianhydride were weighed and added to the reactor. Four times the total mass of 2,2-dihydroxymethylbutyric acid and 4,4'-biphenyl dianhydride in the reactor were then added to the reactor and stirred until completely dissolved. Next, 5% of the total mass of 2,2-dihydroxymethylbutyric acid and 4,4'-biphenyl dianhydride in the reactor, nano-silica (70 nm particle size), and 0.4% of the total mass of 2,2-dihydroxymethylbutyric acid and 4,4'-biphenyl dianhydride in the reactor were weighed and added to the reactor. The mixture was first stirred at 500 rpm for 30 min, then dispersed using 400 W of ultrasonic power for 20 min. Finally, the reactor was shut off, and nitrogen gas was introduced to replace the air inside the reactor. The reactor rotation speed was adjusted to 200 r / min, and then the reactor was heated to 150°C via an electric heating system at a heating rate of 0.5°C / min. The reaction was carried out at this temperature with stirring for 5 hours. After the reaction was completed, the temperature was lowered to 70°C and maintained at this temperature. At this temperature, the pH of the mixture inside the reactor was adjusted with a 0.1 mol / L sodium hydroxide solution until it reached neutral. Then, the rotation speed was increased to 600 r / min and stirring and emulsification were continued for 30 minutes. Finally, the mixture was allowed to cool naturally to room temperature to obtain a hydroxyl-terminated hyperbranched polyester-coated emulsion. The remaining preparation process is the same as in Example 4.

[0031] Comparative Example 5 A method for preparing a collapse-resistant polymer material, specifically including the following preparation process: 0.52 mol of 2,2-dihydroxymethylbutyric acid and 0.1 mol of 4,4'-biphenyl dianhydride were weighed and added to the reactor. Four times the total mass of 2,2-dihydroxymethylbutyric acid and 4,4'-biphenyl dianhydride in the reactor were then added to the reactor and stirred until completely dissolved. Next, 5% of the total mass of 2,2-dihydroxymethylbutyric acid and 4,4'-biphenyl dianhydride in the reactor, nano-silica (30 nm particle size), and 0.4% of the total mass of 2,2-dihydroxymethylbutyric acid and 4,4'-biphenyl dianhydride in the reactor were weighed and added to the reactor. The mixture was first stirred at 500 rpm for 30 min, then dispersed using 400 W of ultrasonic power for 20 min. Finally, the reactor was closed, and nitrogen gas was introduced to replace the air inside the reactor. The reactor rotation speed was adjusted to 200 r / min, and then the reactor was heated to 150℃ via an electric heating system at a heating rate of 0.5℃ / min. The reaction was carried out at this temperature with stirring for 5 hours. After the reaction, the temperature was lowered to 70℃ and maintained. At this temperature, the pH of the mixture inside the reactor was adjusted with a 0.1 mol / L sodium hydroxide solution until neutral. The rotation speed was then increased to 600 r / min and stirring was continued for 30 minutes. Finally, the mixture was allowed to cool naturally to room temperature to obtain a hydroxyl-terminated hyperbranched polyester-coated emulsion. 20 parts by weight of 3-isopropyl-dimethylbenzyl isocyanate, 60 parts by weight of acrylate (obtained by mixing methyl methacrylate, lauryl methacrylate, and octadecyl methacrylate in a weight ratio of 20:40:40), 0.2 parts by weight of dopamine, and 150 parts by weight of deionized water were weighed. Two parts by weight of a composite dispersant (composed of sodium dodecylbenzenesulfonate and emulsifier OP-10 in a weight ratio of 10:5) and 0.3 parts by weight of dibutyltin dilaurate were mixed together. The mixture was then placed in a high-speed homogenizer and mixed, dispersed and emulsified at a speed of 8000 r / min until homogeneous. The mixture was then transferred to a reaction vessel, the reaction vessel was closed, and nitrogen gas was introduced to replace the air inside the reaction vessel. The speed of the reaction vessel was controlled at 250 r / min, and the reaction vessel was heated to 75°C by an electric heating system. The reaction was carried out at this temperature for 2.5 hours. After the reaction was completed, the temperature was lowered to 40°C and the mixture was discharged. The mixture was then allowed to cool naturally to room temperature to obtain a polyacrylate coating liquid containing isocyanate groups. The remaining preparation process is the same as in Example 4.

[0032] 350 mL of deionized water, 10.5 g of sodium bentonite, and 50 g of shale particles (obtained by crushing shale and screening through a 2.0 mm sieve, and dried to constant weight at 105 °C before use) were mixed and stirred at high speed to form a base slurry. 8.2 g of the polymer materials obtained in Examples 1-4 and Comparative Examples 1-5 were weighed and mixed with the base slurry at a speed of 10000 r / min for 30 min. After hot rolling treatment in a hot rolling oven at 150 °C for 16 h, the filtration loss was tested for 30 min using a 0.22 μm filter membrane at a pressure of 2 MPa. The results are shown in Table 1 below.

[0033] Table 1 Filtration Loss Source of materials Filtration loss (mL) Example 1 24.5 Example 2 23.6 Example 3 21.3 Example 4 20.9 Comparative Example 1 35.1 Comparative Example 2 37.3 Comparative Example 3 43.8 Comparative Example 4 38.9 Comparative Example 5 39.6 350 mL of deionized water, 10.5 g of sodium bentonite, and 50 g of shale particles (obtained by crushing shale and screening through a 2.0 mm sieve, and dried to constant weight at 105 °C before use) were mixed and stirred at high speed to form a base slurry. 8.2 g of the polymer materials obtained in Examples 1-4 and Comparative Examples 1-5 were weighed and mixed with the base slurry at 10000 r / min for 30 min. Then, the mixture was hot-rolled in a hot tumbler at 150 °C for 16 h. The shale particles were filtered and recovered, and dried to constant weight at 105 °C, which was recorded as m. The shale recovery rate was calculated according to the formula: recovery rate = m / 50 × 100%. The results are shown in Table 2 below.

[0034] Table 2 Recovery Rate Source of materials Recovery rate (%) Example 1 80.6 Example 2 82.1 Example 3 84.7 Example 4 85.3 Comparative Example 1 66.3 Comparative Example 2 64.8 Comparative Example 3 49.5 Comparative Example 4 59.4 Comparative Example 5 57.6 Based on Tables 1 and 2 above, the following conclusions can be drawn: (1) As can be seen from Examples 1 to 4, the polymer material prepared by the present invention has low filtration loss and high recovery rate, indicating that it has good anti-collapse performance.

[0035] (2) Comparative Example 1 shows that the polymer material prepared has poor anti-collapse performance. This may be because although trimethylolpropane can be used to prepare hyperbranched polyester, it does not contain carboxyl groups in its structure. As a result, the prepared hydroxyl-terminated hyperbranched polyester coating liquid cannot achieve self-emulsification by adjusting the pH. Consequently, the hydroxyl-terminated hyperbranched polyester coating liquid has poor compatibility with the isocyanate-containing polyacrylate coating liquid, and phase separation is likely to occur. It cannot be mixed evenly to react, which leads to poor anti-collapse performance of the polymer material.

[0036] (3) Comparative Example 2 shows that the polymer material prepared has poor anti-collapse performance. This may be because, on the one hand, maleic anhydride does not contain benzene rings, resulting in poor anti-collapse performance of the polymer material under high temperature environment and poor high temperature resistance. On the other hand, maleic anhydride has fewer anhydride structures than 4,4'-diphenyl ether dianhydride, resulting in lower reactivity. This may not only easily lead to fewer cross-linked structures and a loose polymer structure that cannot form a stable three-dimensional encapsulated network structure, but also the fewer cross-linked structures easily lead to a poorer encapsulation effect on nano-silica, thereby weakening the anti-collapse performance.

[0037] (4) Comparative Example 3 shows that the polymer material prepared has poor anti-collapse performance. This may be because although nano-calcium carbonate also has a physical blocking effect, in this system, due to the presence of a lot of acid anhydride in the reaction system for preparing hyperbranched polyester, an acidic environment is easily generated during the reaction process, which leads to the nano-calcium carbonate being easily acidified and losing its blocking activity. As a result, the chemical blocking effect relying solely on the adhesion of dopamine's oxidative self-polymerization is poor and cannot meet the requirements for use.

[0038] (5) Comparative Example 4 shows that the polymer material prepared has poor anti-collapse performance. This may be because when using nano-silica with a larger particle size, the encapsulation method of this system may be difficult to effectively deposit on the surface of nano-silica with a large particle size, resulting in poor dispersion and possible partial agglomeration, which in turn affects the sealing effect of nano-silica.

[0039] (6) Comparative Example 5 shows that the prepared polymer material has poor anti-collapse performance. This may be because when the ratio of soft and hard monomers in the acrylate is changed, the soft monomers lauryl methacrylate and octadecyl methacrylate may be excessive, resulting in low strength of the polymer network structure, low thermal stability at high temperature, easy degradation and failure, and thus poor anti-collapse performance.

[0040] The embodiments described above provide a detailed explanation of the technical solutions and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Various changes and modifications can be made to the present invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed.

Claims

1. A method for preparing a collapse-resistant polymer material, characterized in that, The preparation method includes the following steps: A mixture of polyhydroxy branched monomers, polybasic acid anhydrides, organic solvents, inorganic nano-blocking agents and catalysts was heated to 130℃~150℃ for 4h~5h, then cooled to 60℃~70℃ and neutralized with alkali to obtain a hydroxyl-terminated hyperbranched polyester coating emulsion. Unsaturated isocyanate compound, acrylate, dopamine, deionized water, composite dispersant and initiator are mixed in a weight ratio of 1~2:4~6:0.01~0.02:9~15:0.1~0.2:0.02~0.03 and heated to 75℃~80℃ for 2.5h~3.5h to obtain an isocyanate-containing polyacrylate coated solution; The polymer material is obtained by mixing a hydroxyl-terminated hyperbranched polyester coating emulsion, an isocyanate-containing polyacrylate coating liquid, and an organotin catalyst in a weight ratio of 1:0.1~0.4:0.005 and heating to 60℃~70℃ for 2 hours.

2. The method for preparing an anti-collapse polymer material according to claim 1, characterized in that, The polyhydroxy branched monomer includes 2,2-dihydroxymethylbutyric acid.

3. The method for preparing an anti-collapse polymer material according to claim 1, characterized in that, The polyacid anhydride includes 4,4'-biphenyl ether dianhydride.

4. The method for preparing an anti-collapse polymer material according to claim 1, characterized in that, The organic solvent includes N,N-dimethylformamide or N,N-dimethylacetamide.

5. The method for preparing an anti-collapse polymer material according to claim 1, characterized in that, The inorganic nano-blocking agent includes nano-silica.

6. The method for preparing an anti-collapse polymer material according to claim 1, characterized in that, The catalyst includes p-toluenesulfonic acid.

7. The method for preparing an anti-collapse polymer material according to claim 1, characterized in that, The molar ratio of the polyhydroxy branched monomer to the polybasic acid anhydride is 4~5.2:1, the amount of the organic solvent used is 3 to 4 times the total mass of the polyhydroxy branched monomer and the polybasic acid anhydride, the amount of the inorganic nano-blocking agent used is 2% to 5% of the total mass of the polyhydroxy branched monomer and the polybasic acid anhydride, and the amount of the catalyst used is 0.2% to 0.4% of the total mass of the polyhydroxy branched monomer and the polybasic acid anhydride.

8. The method for preparing an anti-collapse polymer material according to claim 1, characterized in that, The unsaturated isocyanate compound includes 3-isopropyl-dimethylbenzyl isocyanate.

9. The method for preparing an anti-collapse polymer material according to claim 1, characterized in that, The acrylate is composed of methyl methacrylate, lauryl methacrylate and octadecyl methacrylate in a weight ratio of 3:1:

1.

10. A polymer material for preventing collapse, characterized in that, The polymer material is prepared by the method for preparing an anti-collapse polymer material according to any one of claims 1 to 9.