A method for preparing a hyperbranched polymer, a modified toughened epoxy resin, a coating, and applications thereof

Abstract

The application discloses a kind of hyperbranched polymer, modified toughened epoxy resin, preparation method and application of coating, linolenic acid ester compound and acid anhydride compound are used as raw material, with imine compound, monoamino compound sequentially through Diels-Alder addition reaction and amidation reaction to obtain acid anhydride, hydroxyl multifunctional hyperbranched polymer, then with epoxy resin mixed one-pot method synthesis hyperbranched polymer modified toughened epoxy resin, further prepare high toughness, high bonding strength modified toughened epoxy resin coating, can resist-196 ℃ liquid nitrogen immersion not cracking, not fall off.The raw material used in the application is simple and easy to obtain, and does not need to be separated and purified, a low-cost green synthesis technology is used without solvent, the operation steps are simple, VOC emission is reduced, the requirement for equipment is low, and industrial production is easy.The hyperbranched polymer modified toughened epoxy resin coating prepared by the application is applied to the field of super-low temperature protection such as LNG ship pipeline.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials and coating technology, specifically relating to a hyperbranched polymer, a modified toughened epoxy resin, a coating preparation method and its application, especially suitable for the field of ultra-low temperature protection. Background Technology

[0002] LNG carrier pipelines (-162℃) are core facilities in the liquefied natural gas industry chain, and their protection technology directly relates to energy security and pipeline durability. Epoxy resins, with their excellent mechanical properties, chemical corrosion resistance, adhesion, and electrical insulation, are widely used in aerospace, electronic packaging, coatings, adhesives, and composite materials. However, their high cross-linking density leads to high brittleness and poor impact resistance after curing, and stress concentration easily triggers crack propagation, limiting their application in high-end fields. Traditional toughening methods can improve toughness, but often come with a significant decrease in heat resistance, modulus, or processing performance, making it difficult to meet high-performance requirements. Elastomer toughening requires high addition levels (10-20%), easily sacrificing glass transition temperature and rigidity, and room temperature curing systems are not effective. Thermoplastic resin toughening introduces phase separation structures to improve toughness, but increased viscosity leads to processing difficulties, and precise control of phase transition temperature is required. Nanoparticle toughening requires solving the problem of dispersion uniformity, and agglomeration easily leads to weak interfacial effects.

[0003] Hyperbranched polymers possess characteristics such as a three-dimensional highly branched structure, low chain entanglement, high functional group density, and ease of functionalization. Their globular molecular configuration provides high free volume, promoting stress dispersion. Abundant end groups (such as epoxy and carboxyl groups) form chemical bonds or hydrogen bonds with the resin matrix, enhancing interfacial bonding and becoming a breakthrough solution for epoxy resin toughening. For example, hyperbranched polyether epoxy resins significantly improve the impact strength of coatings (up to 35.2 kJ / m). 2 The existing technology has the following problems: (1) insufficient interfacial bonding efficiency between hyperbranched polymers and epoxy resins; (2) insufficient synergistic optimization of toughening and protective properties; (3) some processes are complex and require high temperature or large amount of solvent. Summary of the Invention

[0004] To address the above problems, this invention provides a method for preparing hyperbranched polymers, modified toughened epoxy resins, coatings, and their applications.

[0005] This invention involves mixing linolenic acid esters, acid anhydrides, and imine compounds, stirring and heating the mixture for 1-4 hours, then cooling it to room temperature. A monoamine compound is then added, and the mixture is stirred for 3-6 hours. After the reaction, the mixture is cooled to room temperature and poured out, yielding a hyperbranched polymer with multifunctional anhydrides and hydroxyl groups. This polymer is then mixed with epoxy resin in a one-pot process to prepare a hyperbranched polymer-modified toughened epoxy resin, which is subsequently used to prepare a modified and toughened epoxy resin coating. This coating utilizes the numerous cavities within the hyperbranched polymer structure to induce yielding and plastic deformation, forming microscopic phase separation zones that absorb impact energy, improve the toughness of the epoxy resin, and also increase the adhesive strength of the coating. This invention employs a low-cost, green synthesis technology that eliminates the need for solvents, reducing VOC emissions. The prepared hyperbranched polymer-modified toughened epoxy resin coating is applicable to ultra-low temperature (-196℃) protection applications.

[0006] The present invention adopts the following technical solution: In a first aspect, the present invention provides a method for preparing a hyperbranched polymer, comprising the following steps: S1. Mix linolenic acid esters, acid anhydrides, and imines, stir and heat for 1-4 hours, then cool to room temperature; S2. Add the monoamine compound and stir the reaction for 3-6 hours. S3. After the reaction is complete, cool to room temperature and pour out the product, which is a multifunctional hyperbranched polymer with anhydrides and hydroxyl groups.

[0007] Preferably, in S1, the linoleic acid ester compound is one or more of conjugated linolenic acid glyceride, glyceryl trioleate, glyceryl tripalmitate, and glyceryl tristearate.

[0008] Furthermore, the linolenic acid esters are one or both of conjugated linolenic acid glycerides and glyceryl trioleate.

[0009] Preferably, in S1, the acid anhydride compound is one or more of succinic anhydride, maleic anhydride, acetic anhydride, benzoic anhydride, and glutaric anhydride.

[0010] Furthermore, the acid anhydride compound is one or more of succinic anhydride, maleic anhydride, and glutaric anhydride.

[0011] Preferably, in S1, the imine compound is one or more of 4-(2,4-dioxoimidazoline-1-yl)benzoic acid, 2-(5-amino-1,3-dioxoisoindol-2-yl)acetic acid, and bismaleimide ethane.

[0012] Furthermore, the imine compound is one or both of 2-(5-amino-1,3-dioxoisoindol-2-yl)acetic acid and bismaleimide ethane.

[0013] Preferably, in step S1, the heating temperature is 70-110°C.

[0014] Preferably, in S2, the monoamino compound is one or more of ethanolamine, propanolamine, isopropanolamine, butanolamine, isobutanolamine, diethylene glycolamine, pentanolamine, and hexanolamine.

[0015] Furthermore, the monoamino compound is one or more of ethanolamine, propanolamine, and diethylene glycolamine.

[0016] Secondly, the present invention provides a hyperbranched polymer, which is prepared by the above-described preparation method.

[0017] Thirdly, the present invention provides a method for preparing a modified toughened epoxy resin, wherein the modified toughened epoxy resin is a modified toughened epoxy resin by adding the above-mentioned hyperbranched polymer, and the preparation method includes the following steps: S1. Mix the above hyperbranched polymer and epoxy resin evenly. S2. After heating and reacting for 1-4 hours, cool to room temperature to obtain hyperbranched polymer-modified toughened epoxy resin.

[0018] Preferably, in step S1, the mass ratio of the hyperbranched polymer to the epoxy resin is 1:5-20.

[0019] Furthermore, the mass ratio of hyperbranched polymer to epoxy resin is 1:5-15.

[0020] Preferably, in S1, the epoxy resin is one or more of E51, E44, F51, and F44.

[0021] Preferably, in step S2, the heating temperature is 150-200℃.

[0022] Furthermore, the heating temperature is 170-200℃.

[0023] Fourthly, the present invention provides a modified toughened epoxy resin, which is a hyperbranched polymer modified toughened epoxy resin prepared by the above-described preparation method.

[0024] Fifthly, the present invention provides a method for preparing a coating, wherein the coating is a coating obtained from the above-mentioned modified toughened epoxy resin, and the preparation method includes the following steps: S1. Add dispersant, defoamer, diluent, filler, and pigment to the paint mixing tank, grind and disperse at high speed, and monitor the fineness; S2. Then, add the above-mentioned modified toughened epoxy resin, epoxy resin, remaining defoamer, leveling agent, and wetting agent to the paint mixing tank in sequence and disperse at high speed. S3. Adjust the viscosity with a diluent, filter, and the resulting hyperbranched polymer-modified toughened epoxy resin coating is ready. S4. Prepare a hyperbranched polymer-modified toughened epoxy resin coating by spraying a hyperbranched polymer-modified toughened epoxy resin coating with a polyamide curing agent.

[0025] In a sixth aspect, the present invention provides a coating, which is a hyperbranched polymer-modified toughened epoxy resin coating prepared by the above-described preparation method.

[0026] Seventhly, the present invention provides an application of the above-mentioned coating for cryogenic protection fields such as LNG storage tanks and pipelines; in the application of the coating in the cryogenic (-196℃) protection field, the coating is sprayed onto the substrate with a curing agent to form a uniform and dense paint film. After complete drying, it is immersed in liquid nitrogen for 100 hours. The paint film of the sample is taken out and is flat and intact, without embrittlement or cracking. The adhesion is also 0 grade (cross-cut test) compared with that before the test. Compared with the epoxy resin system without hyperbranched polymer modification, the tensile shear strength of the product of the present invention is increased by up to 26%.

[0027] Compared with the prior art, the present invention has the following beneficial effects: (1) This invention uses a two-step continuous reaction of Diels-Alder addition reaction and amidation reaction to accurately prepare anhydride and hydroxyl multifunctional hyperbranched polymers, solving the problem of single function and complicated reaction steps of traditional hyperbranched polymers; the subsequent mixing with epoxy resin adopts a one-pot synthesis modification system, which simplifies the process flow, reduces production costs, and improves the feasibility of industrial application; the epoxy resin coating is modified and toughened by anhydride and hydroxyl multifunctional hyperbranched polymer, so that the coating does not crack or peel at -196℃ and its performance is improved. The low temperature flexibility is improved to the highest level of 1mm, and the bonding strength is improved by 26%, filling the technical gap of conventional epoxy resin coatings with high low temperature brittleness and insufficient resistance to extreme low temperature.

[0028] (2) The present invention adopts a graded toughening design, introducing hyperbranched polymers into the epoxy coating system, which synergistically improves the toughness of the coating at multiple scales, especially in ultra-low temperature environments: at the micro scale, relying on the crack anchoring mechanism, the hyperbranched polymer branches effectively hinder the propagation of microcracks, causing stress field distortion at the crack tip and significantly improving the crack propagation resistance; at the meso scale, through the shear yielding mechanism, the hyperbranched polymer induces the matrix to undergo controllable plastic deformation, forming an energy dissipation shear band, which efficiently absorbs the impact energy of external forces; at the macro scale, with the help of the cavitation energy dissipation mechanism, the large number of cavities in the structure of the hyperbranched polymer itself undergo yielding and plastic deformation when subjected to force, forming a micro-phase separation zone, which dissipates most of the impact energy.

[0029] (3) This invention breaks through the limitations of traditional hyperbranched polymer raw material selection. The raw material source is green and accessible, and lays the structural foundation for subsequent multifunctional modification. Furthermore, the hyperbranched polymer modified toughened epoxy resin is a low-cost green synthesis technology that does not require solvents and reduces VOC emissions. Attached Figure Description

[0030] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 This is a schematic diagram of the structure of HBP-1, a multifunctional hyperbranched polymer with anhydrides and hydroxyl groups, in Example 1 of the present invention. Figure 2 The above is the 1H NMR spectrum of HBP-1, a multifunctional hyperbranched polymer with anhydrides and hydroxyl groups, in Example 1 of this invention. Figure 3 The infrared spectrum of HBP-1, a multifunctional hyperbranched polymer with anhydride and hydroxyl groups, in Example 1 of this invention; Figure 4 The above is the 1H NMR spectrum of the hyperbranched polymer HBP-1 modified and toughened epoxy resin HBEP-1 in Example 2 of this invention. Figure 5 The infrared spectrum of the hyperbranched polymer HBP-1 modified and toughened epoxy resin HBEP-1 in Example 2 of this invention is shown. Detailed Implementation

[0031] The present invention will be further described in detail below with reference to specific embodiments. The processes, conditions, reagents, experimental methods, etc., for implementing the present invention, except as specifically mentioned below, are all common knowledge and general knowledge in the art. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0032] This invention provides a method for preparing hyperbranched polymers, modified toughened epoxy resins, and coatings, as well as their applications. Linoleic acid esters and anhydrides are used as raw materials, and these are reacted sequentially with imine compounds and monoamine compounds via Diels-Alder addition and amidation reactions to obtain a multifunctional hyperbranched polymer with anhydrides and hydroxyl groups. This polymer is then mixed with epoxy resin in a one-pot process to synthesize a hyperbranched polymer-modified toughened epoxy resin, thereby preparing a high-toughness, high-adhesion-strength modified toughened epoxy resin coating capable of withstanding liquid nitrogen immersion at -196°C without cracking or peeling. This invention uses readily available and simple raw materials, requires no separation or purification, employs a low-cost, green synthesis technology without solvents, has simple operation steps, reduces VOC emissions, has low equipment requirements, and is easy to industrialize. The hyperbranched polymer-modified toughened epoxy resin coating prepared by this invention can be applied in cryogenic protection fields such as LNG ship pipelines.

[0033] Example 1 Preparation methods of hyperbranched polymers: In a four-necked flask equipped with a mechanical stirrer, thermometer, and condenser, 40.3 g (0.114 mol) of conjugated linolenic acid glycerol ester (M=352.5), 12.1 g (0.12 mol) of maleic anhydride (M=98), and 3.2 g (0.015 mol) of bismaleimide ethane (M=220) were added. The mixture was stirred and heated at 90 °C for 2 h. After cooling to room temperature, 2.9 g (0.028 mol) of diethylene glycolamine (M=105) was added. The mixture was stirred for 4 h and then cooled to room temperature to obtain the target anhydride and hydroxyl multifunctional hyperbranched polymer, denoted as HBP-1. The structural diagram is shown below. Figure 1 As shown. The HBP-1 1H NMR characterization results are as follows. Figure 2 As shown, the chemical shifts δ=5.75~5.95 represent the positions of the hydrogen atom absorption peaks on the -C=C- of cyclohexene in bismaleimide ethane; δ=5.5~5.75 represent the positions of the hydrogen atom absorption peaks on the -C=C- of maleic anhydride; δ=5.25~5.5 represent the positions of the hydrogen atom absorption peaks on the -C=C- of conjugated linolenic acid glyceride; δ=4.25~4.4 represent the positions of the hydrogen atom absorption peaks on the -C- of maleic anhydride; δ=4.1~4.2 represent the positions of the hydrogen atom absorption peaks on the -C- of bismaleimide ethane; δ=3.3~3.5 represent the positions of the hydrogen atom absorption peaks on the methylene group in diethylene glycolamine; and δ=3.2~3.3 represent the positions of the hydrogen atom absorption peaks on the methylene group in bismaleimide ethane. The HBP-1 infrared spectral characterization results are as follows: Figure 3 As shown, at 3021cm -1 The peak at 2925 cm⁻¹ represents the stretching vibration of -NH⁻ in diethylene glycolamine after the reaction. -1 The peak at 2854 cm⁻¹ is stronger due to the stretching vibration of -OH. -1 1738cm -1 The absorption peak is due to the stretching vibration of the -OH group in the carboxyl group; 1774 cm⁻¹ -1 This is the absorption peak of the stretching vibration of -C=O in maleic anhydride; 1458 cm⁻¹ -1 1410cm -1 The strong characteristic absorption peak of the methylene group of conjugated linolenic acid glycerol ester; 1378 cm⁻¹ -1 1246cm -1 The weak characteristic absorption peak of the methylene group of conjugated linolenic acid glycerol ester; 1246 cm⁻¹ -1 The absorption peak is the stretching vibration of -COC-; 785 cm⁻¹ -1 760cm -1 The absorption peak is due to the out-of-plane bending vibration of -C=CH.

[0034] 100.9 g (0.114 mol) of glyceryl trioleate (M=885.4), 12.0 g (0.12 mol) of succinic anhydride (M=100), and 3.2 g (0.015 mol) of 2-(5-amino-1,3-dioxoisoindol-2-yl)acetic acid (M=220) were added to a four-necked flask equipped with a mechanical stirrer, thermometer, and condenser. The mixture was stirred and heated at 100 °C for 1.5 h. After cooling to room temperature, 1.7 g (0.028 mol) of ethanolamine (M=61) was added. The mixture was stirred for 5 h and then cooled to room temperature to obtain the anhydride and hydroxyl multifunctional hyperbranched polymer, denoted as HBP-2.

[0035] 40.3 g (0.114 mol) of conjugated linolenic acid glyceride (M=352.5), 13.7 g (0.12 mol) of glutaric anhydride (M=114), and 3.2 g (0.015 mol) of bismaleimide ethane (M=220) were added to a four-necked flask equipped with a mechanical stirrer, thermometer, and condenser. The mixture was stirred and heated at 80 °C for 3.5 h. After cooling to room temperature, 2.1 g (0.028 mol) of propanolamine (M=75) was added. After stirring for 6 h, the mixture was cooled to room temperature and poured out to obtain the target anhydride and hydroxyl multifunctional hyperbranched polymer, denoted as HBP-3.

[0036] Example 2 Preparation method of hyperbranched polymer-modified toughened epoxy resin: The synthesized hyperbranched polymer HBP-1 and epoxy resin E51 were mixed and stirred evenly at a mass ratio of 1:10. The mixture was heated to 190℃ and reacted for 2 hours. After heating was stopped, the mixture was cooled to room temperature, which yielded the hyperbranched polymer-modified toughened epoxy resin, denoted as HBEP-1. The 1H NMR characterization results of HBEP-1 are as follows: Figure 4 As shown, chemical shifts δ=6.8 and 7.1 represent the positions of the hydrogen atom absorption peaks on the benzene ring of the epoxy resin; chemical shifts δ=4.1~4.2 represent the positions of the hydrogen atom absorption peaks on the -C- ring of bismaleimide ethane; chemical shifts δ=3.9~4.0 represent the positions of the hydrogen atom absorption peaks on the -COC- ring of diethylene glycolamine; chemical shifts δ=3.3~3.35 represent the positions of the hydrogen atom absorption peaks on the O=COC- ring of conjugated glycerol linoleate; chemical shifts δ=2.8~2.9 represent the positions of the hydrogen atom absorption peaks on the -NC- ring of diethylene glycolamine; and chemical shifts δ=2.72~2.75 represent the positions of the hydrogen atom absorption peaks on the -NC- ring of bismaleimide ethane. The infrared spectral characterization results of HBEP-1 are as follows: Figure 5 As shown, at 3056cm -1 2965cm -1 2926cm -1The peak at 1735 cm⁻¹ represents the stretching vibration of the aromatic ring CH in epoxy resin. -1 This is the absorption peak of the stretching vibration of -C=O in acid anhydrides; 1606 cm⁻¹ -1 This is the absorption peak of the stretching vibration of -C=O in carboxylic acids; 1507 cm⁻¹ -1 The absorption peak is the stretching vibration of -C=C-; 1455 cm⁻¹ -1 The absorption peak is due to the methylene bending vibration; 1230 cm⁻¹ -1 The absorption peak is the stretching vibration of CO-; 1181 cm⁻¹ -1 The absorption peak is the stretching vibration of -COC-; 1032 cm⁻¹ -1 The absorption peak for the stretching vibration of -CN- is 914 cm⁻¹. -1 The peak represents the vibrational absorption of the epoxy group; 827 cm⁻¹ -1 This is the absorption peak due to the substitution vibration of the benzene ring.

[0037] The synthesized hyperbranched polymer HBP-2 and epoxy resin E44 were mixed and stirred evenly at a mass ratio of 1:15. The mixture was heated to 180°C and reacted for 3 hours. After heating was stopped, the mixture was cooled to room temperature. This mixture is the hyperbranched polymer-modified toughened epoxy resin, denoted as HBEP-2.

[0038] The synthesized hyperbranched polymer HBP-3 and epoxy resin F51 were mixed and stirred evenly at a mass ratio of 1:5, heated to 200℃, and reacted for 1.5 hours. After heating was stopped, the mixture was cooled to room temperature, which is the hyperbranched polymer modified toughened epoxy resin, denoted as HBEP-3.

[0039] Example 3 This invention provides a hyperbranched polymer-modified toughened epoxy resin coating, the raw material composition of which is shown in Table 1: Table 1. Raw material composition of hyperbranched polymer-coated toughened epoxy resin HBEP-1 coating.

[0040] Add 0.5 parts of dispersant BYK110, 0.1 parts of defoamer Tego900, 25 parts of diluent xylene, 35 parts of talc, and 15 parts of titanium dioxide to a paint mixing tank, and grind and disperse at a high speed of 1500 r / min, monitoring the fineness to below 40 μm; Then, add 35 parts of modified toughened epoxy resin HBEP-1, 15 parts of epoxy resin CY183, 0.1 parts of the remaining defoamer Tego9000, and 0.8 parts of leveling agent BYK354 into the paint mixing tank in sequence, and disperse at high speed of 1000r / min. Adjust the viscosity with xylene diluent to 10-15s for Fore-4 cup, filter, and the resulting product is component A of the hyperbranched polymer-modified epoxy resin coating. Component A and component B were mixed evenly at a mass ratio of 2.5:1 and sprayed to prepare a coating test piece. The performance test results are shown in Table 2.

[0041] Example 4 This invention provides a hyperbranched polymer-modified toughened epoxy resin coating, similar to Example 3, except that the modified toughened epoxy resin HBEP-1 is replaced with modified toughened epoxy resin HBEP-2. Performance test results are shown in Table 2.

[0042] Example 5 This invention provides a hyperbranched polymer-modified toughened epoxy resin coating, similar to Example 3, except that the modified toughened epoxy resin HBEP-1 is replaced with modified toughened epoxy resin HBEP-3. Performance test results are shown in Table 2.

[0043] Comparative Example 1 An unmodified epoxy resin coating, similar to Example 3, except that the modified toughening epoxy resin HBEP-1 is replaced with epoxy resin E51. Performance test results are shown in Table 2.

[0044] Comparative Example 2 A rubber particle-modified epoxy resin coating, similar to Example 3, differs in that: 35 parts of modified toughening epoxy resin HBEP-1 are replaced with 30 parts of epoxy resin E51 and 5 parts of liquid nitrile rubber particles; the liquid nitrile rubber particles are added together with epoxy resin E51 during preparation. Performance test results are shown in Table 2.

[0045] Comparative Example 3 A polyurethane toughening agent modified epoxy resin coating, similar to Example 3, differs in that: 35 parts of modified toughening epoxy resin HBEP-1 are replaced with 30 parts of epoxy resin E51 and 5 parts of polyurethane toughening agent; the polyurethane toughening agent is added together with epoxy resin E51 during preparation. Performance test results are shown in Table 2.

[0046] Comparative Example 4 An anhydride-functionalized glyceryl linoleate-modified epoxy resin coating is prepared by the following steps: Add 40.3 g (0.114 mol) of conjugated linolenic acid glyceride (M=352.5) ​​and 12.1 g (0.12 mol) of maleic anhydride (M=98) to a four-necked flask equipped with a mechanical stirrer, thermometer and condenser. Stir and heat at 90 °C for 2 h, cool to room temperature, stir for 4 h, and pour out to obtain anhydride-functionalized linolenic acid glyceride, denoted as HBP-4; The synthesized anhydride functionalized linolenic acid glyceride HBP-4 and epoxy resin E51 were mixed and stirred evenly at a mass ratio of 1:10. The mixture was heated to 190℃ and reacted for 2 hours. After heating was stopped and the mixture was cooled to room temperature, the resulting product was anhydride functionalized linolenic acid glyceride modified epoxy resin, denoted as HBEP-4. The raw material composition and preparation method of the anhydride-functionalized linolenic acid glyceryl ester modified epoxy resin coating are the same as in Example 3, except that the modified toughening epoxy resin HBEP-1 is replaced with modified epoxy resin HBEP-4. The performance test results are shown in Table 2.

[0047] Performance testing The test standards for each performance index are as follows: room temperature flexibility (GB / T 1731), low temperature flexibility (GB / T 1731-2020), room temperature adhesion (GB / T 9286), low temperature adhesion (GB / T 9286), room temperature impact strength (GB / T 1732), low temperature impact strength (GB / T 1732), tensile shear strength (GB / T 7124), weather resistance (GB / T 1767), and salt spray resistance (GB / T 1771). The low temperature performance test method is to prepare paint film test pieces as required, immerse them in liquid nitrogen (-196℃) for 48 hours, remove them, cool them to room temperature, and then test each index. The performance test results of Examples 3-5 and Comparative Examples 1-4 are shown in Table 2.

[0048] Table 2 Performance test results of Examples 3-5 and Comparative Examples 1-4

[0049] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any form or substance. It should be noted that those skilled in the art can make various improvements and additions without departing from the present invention, and these improvements and additions should also be considered within the scope of protection of the present invention. Any modifications, alterations, and equivalent changes made by those skilled in the art based on the above-disclosed technical content without departing from the spirit and scope of the present invention are equivalent embodiments of the present invention. Furthermore, any modifications, alterations, and evolutions made to the above embodiments based on the essential technology of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A method for preparing a hyperbranched polymer, characterized in that, Includes the following steps: S1. Mix linolenic acid esters, acid anhydrides, and imines, stir and heat for 1-4 hours, then cool to room temperature; S2. Add the monoamine compound and stir the reaction for 3-6 hours. S3. After the reaction is complete, cool to room temperature and pour out the product, which is a multifunctional hyperbranched polymer with anhydrides and hydroxyl groups.

2. The method for preparing the hyperbranched polymer according to claim 1, characterized in that, In S1, the linolenic acid ester compound is one or two of conjugated linolenic acid glyceride and glyceryl trioleate; the acid anhydride compound is one or more of succinic anhydride, maleic anhydride and glutaric anhydride; the imine compound is one or two of 2-(5-amino-1,3-dioxoisoindol-2-yl)acetic acid and bismaleimide ethane; and the heating temperature is 70-110℃.

3. The method for preparing the hyperbranched polymer according to claim 1, characterized in that, In S2, the monoamino compound is one or more of ethanolamine, propanolamine, and diethylene glycolamine.

4. A hyperbranched polymer, characterized in that, Hyperbranched polymer prepared by any one of claims 1-3.

5. A method for preparing a modified toughened epoxy resin, characterized in that, The modified toughened epoxy resin is a modified and toughened epoxy resin by adding the hyperbranched polymer as described in claim 4, and its preparation method includes the following steps: S1. Mix and stir the hyperbranched polymer and epoxy resin as described in claim 4 until homogeneous; S2. After heating and reacting at 150-200℃ for 1-4 hours, cool to room temperature to obtain hyperbranched polymer-modified toughened epoxy resin.

6. The preparation method according to claim 5, characterized in that, In S1, the mass ratio of hyperbranched polymer to epoxy resin is 1:5-20; the epoxy resin is one or more of E51, E44, and F51.

7. A modified toughened epoxy resin, characterized in that, Hyperbranched polymer-modified toughened epoxy resin prepared by the preparation method described in claim 5 or 6.

8. A method for preparing a coating, characterized in that, The coating is made of the modified toughened epoxy resin according to claim 7, and its preparation method includes the following steps: S1. Add dispersant, defoamer, diluent, filler, and pigment to the paint mixing tank, grind and disperse at high speed, and monitor the fineness; S2. Then, the modified toughened epoxy resin, epoxy resin, remaining defoamer, and leveling agent described in claim 7 are added sequentially to the paint mixing tank and dispersed at high speed. S3. Adjust the viscosity with a diluent, filter, and the resulting hyperbranched polymer-modified toughened epoxy resin coating is ready. S4. Prepare a hyperbranched polymer-modified toughened epoxy resin coating by spraying a hyperbranched polymer-modified toughened epoxy resin coating with a polyamide curing agent.

9. A coating, characterized in that, Hyperbranched polymer-modified toughened epoxy resin coating prepared by the preparation method described in claim 8.

10. An application of the coating as described in claim 9, characterized in that, Used in the field of cryogenic protection for LNG storage tanks and pipelines.

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