A tear-resistant polyurethane film and a method for producing the same

Abstract

The application belongs to the technical field of polymer material synthesis, and particularly relates to a tear-resistant polyurethane film and a preparation method thereof. The preparation method of the tear-resistant polyurethane film comprises the following steps: (1) adding a macromolecular diol and a diisocyanate into acetone, and stirring and reacting under an inert gas atmosphere; after the reaction, acetone is added to adjust the viscosity, a chain extender and an organic tin catalyst are further added, and heating reaction is performed to obtain a prepolymer solution; functional monomers and a photoinitiator are added into the prepolymer solution, and stirring is performed to obtain a mixed solution; (2) the mixed solution is poured into a mold, and reaction is performed under ultraviolet lamp irradiation; standing and defoaming are performed, and then natural air drying is performed to form a film; and after demolding, the tear-resistant polyurethane film is obtained. The polyurethane film obtained in the application introduces a chain extender with a novel structure and functional monomers, and the polyurethane film is endowed with excellent tear resistance and mechanical strength.

Description

Technical Field

[0001] This invention belongs to the field of polymer material synthesis technology, specifically relating to a tear-resistant polyurethane film and its preparation method. Background Technology

[0002] Polyurethane (PU) materials, due to their excellent mechanical properties, flexibility, and designability, show broad application prospects in the field of building energy conservation, especially as a key encapsulation material or functional layer in thermal insulation systems. Building energy-saving thermal insulation materials, such as the encapsulation film of vacuum insulation panels (VIP) and the reinforced flexible substrate of aerogel composites, require materials that not only possess excellent mechanical strength and toughness to resist punctures, tears, and long-term loads during installation and use, but also good stability and durability. However, traditional polyurethane films, when used as protective or support layers in building thermal insulation materials, often suffer from insufficient tear resistance. They are prone to damage due to stress concentration during construction or use, leading to the failure of the entire insulation system and affecting the long-term stability of its thermal insulation effect. Furthermore, poor mechanical properties of the material itself can limit its application in ultra-thin, high-efficiency insulation structures.

[0003] Currently, methods to improve the mechanical properties of polyurethane films mainly include introducing rigid segments (such as aromatic diisocyanates or small molecule chain extenders) or adding inorganic nanofillers (such as silica or aerogel particles). However, the former often leads to a significant decrease in material flexibility, failing to meet the deformation adaptability required in building applications; the latter is prone to problems such as uneven filler dispersion and poor interfacial compatibility, which not only affect performance reproducibility but may also reduce the uniformity and film-forming properties of the film. Therefore, developing a polyurethane film that simultaneously possesses high tear resistance, good flexibility, and stable processing performance is of great significance for improving the reliability and service life of building energy-saving insulation materials. Summary of the Invention

[0004] To overcome the shortcomings of the prior art, the primary objective of this invention is to provide a method for preparing a tear-resistant polyurethane film.

[0005] Another object of the present invention is to provide a tear-resistant polyurethane film.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] A method for preparing a tear-resistant polyurethane film includes the following steps:

[0008] (1) Add macromolecular diol and diisocyanate to acetone and stir under an inert gas atmosphere; after the reaction, add acetone to adjust the viscosity, then add chain extender and organotin catalyst, heat to react, and obtain a prepolymer solution; add functional monomer and photoinitiator to the prepolymer solution, stir, and obtain a mixed solution.

[0009] (2) Pour the mixed solution into the mold, react under ultraviolet light, let it stand to defoam, and then let it air dry naturally to form a film. After demolding, a tear-resistant polyurethane film is obtained.

[0010] Furthermore, the preparation process of the chain extender mentioned in step (1) is as follows:

[0011] 4-Pyridinecarboxaldehyde was added to a solvent, followed by 2-hydroxypropyl 2-acrylate and a catalyst, and the mixture was stirred to react. After the reaction was completed, the chain extender was obtained by extraction, concentration, drying, filtration, and purification.

[0012] Further, the ratio of 4-pyridinecarboxaldehyde, 2-hydroxypropyl 2-acrylate, catalyst, and solvent is 0.1 mol: 0.3-0.4 mol: 0.3-0.4 mol: 30 mL; the solvent is prepared by mixing 1,4-dioxane and water in equal volumes; the catalyst is triethylenediamine; and the stirring reaction time is 40-48 h.

[0013] Furthermore, the preparation process of the functional monomer mentioned in step (1) is as follows:

[0014] a. Add 2-aminobenzoylhydrazine to a solvent, then add formamide and potassium hydroxide and reflux. After the reaction is complete, extract, wash, dry and concentrate the reaction solution to obtain a crude product. Recrystallize to obtain 2-(1H-1,2,4-triazol-5-yl)aniline.

[0015] b. Add the 2-(1H-1,2,4-triazol-5-yl)aniline to a solvent, and then add γ-thiobutyrolactone to react; after the reaction is completed, wash, dry, concentrate and purify the reaction solution to obtain the functional monomer.

[0016] Further, in step a, the ratio of 2-aminobenzoyl hydrazide, formamide, potassium hydroxide, and solvent is 0.1 mol: 0.15-0.2 mol: 0.15-0.2 mol: 80-100 mL; the solvent is N,N-dimethylformamide; and the reflux reaction time is 3-4 h.

[0017] Further, in step b, the ratio of 2-(1H-1,2,4-triazol-5-yl)aniline, γ-thiobutyrolactone, and solvent is 0.1 mol: 0.1-0.2 mol: 100-150 mL; the solvent is dichloromethane; the reaction temperature is 35-45℃, and the reaction time is 20-24 h.

[0018] Further, in step (1), during the stirring reaction, the ratio of macromolecular diol, diisocyanate, and acetone is 0.01-0.02 mol: 0.02-0.05 mol: 50-70 mL; the ratio of macromolecular diol, chain extender, organotin catalyst, functional monomer, and photoinitiator is 0.01-0.02 mol: 0.01-0.02 mol: 3-9 μL: 0.01-0.02 mol: 0.0001-0.001 mol.

[0019] Further, in step (1), the temperature of the stirring reaction is 80-90℃ and the time is 2-3h; the temperature of the heating reaction is 80-90℃ and the time is 4-5h; in step (2), the wavelength of the ultraviolet lamp is 360-370nm and the reaction time is 20-30min.

[0020] Further, in step (1), the macromolecular diol is vacuum dehydrated at 100-105℃ for 1.5-2h before use; when adjusting the viscosity, the ratio of acetone to macromolecular diol is 150-200 mL: 0.01-0.02 mol; the temperature when adding acetone is 25-45℃; the temperature when adding functional monomers and photoinitiators is 25-45℃.

[0021] The macromolecular diol is selected from either polyethylene glycol or polypropylene glycol, with a number average molecular weight of 600-1500; the diisocyanate is selected from either toluene diisocyanate, diphenylmethane diisocyanate, or hexamethylene diisocyanate; the organotin catalyst is dibutyltin dilaurate; and the photoinitiator is photoinitiator 2959.

[0022] Another objective of this invention is achieved by the following technical solution:

[0023] The tear-resistant polyurethane film of the present invention is prepared according to the above preparation method.

[0024] The present invention has the following advantages over the prior art:

[0025] 1. The chain extender prepared in this invention contains both pyridine rings and acrylate double bonds, endowing polyurethane films with excellent tear resistance and mechanical properties. Specifically, the introduction of rigid pyridine rings can enhance the micro-region stacking of hard segments through π-π stacking and hydrogen bonding, forming a physical cross-linking network and significantly improving the tear resistance and mechanical strength of the polyurethane film. The introduction of acrylate double bonds provides active sites for click reactions, which react with the thiol groups of functional monomers during UV curing to further form a covalent cross-linking network, enhancing the intermolecular forces while maintaining the flexibility of the material, further improving the tear resistance of the polyurethane film.

[0026] 2. This invention covalently bonds a functional monomer containing a 1,2,4-triazole ring to a polyurethane network via a mercapto-olefin click reaction. The NH group of the triazole ring in the functional monomer can form a strong hydrogen bond with the C=O group of the polyurethane hard segment. Furthermore, the polarity of the triazole ring is similar to that of the urethane group in the polyurethane hard segment, resulting in good compatibility with the polyurethane matrix. This effectively promotes the ordered arrangement and microphase separation of the hard segment region, thereby improving the mechanical strength and tear resistance of the material. Detailed Implementation

[0027] The technical solution of the present invention will be further described below with reference to specific embodiments. However, those skilled in the art should understand that the following embodiments are only for illustrating the present invention and should not be regarded as limiting the present invention. Specific conditions not specified in the embodiments are performed according to conventional conditions or conditions recommended by the manufacturer. Unless otherwise specified, the reagents or instruments used are all conventional products obtained through commercial channels.

[0028] Example 1

[0029] A method for preparing a tear-resistant polyurethane film includes the following steps:

[0030] (1) Before use, the macromolecular diol (polyethylene glycol, number average molecular weight of 1000) was dehydrated under vacuum at 100℃ for 2 h. Then, the dehydrated macromolecular diol and diisocyanate (toluene diisocyanate) were added to acetone. The ratio of macromolecular diol, diisocyanate (toluene diisocyanate), and acetone was 0.015 mol: 0.03 mol: 60 mL. The mixture was stirred and reacted at 85℃ under an inert gas atmosphere for 2.5 h. Then, the temperature was lowered to 35℃, and a certain amount of acetone was added to adjust the viscosity. When adjusting the viscosity, the ratio of acetone to macromolecular diol was 180 mL: 0.015 mol. Then, a chain extender and an organotin catalyst (dibutyltin dilaurate) were added. The ratio of macromolecular diol, chain extender, and dibutyltin dilaurate was 0.015 mol: 0.015 mol: 6 μL. The temperature was raised to 85℃ and the reaction was carried out for 4.5 h. h, to obtain a prepolymer solution; cool to 35°C, add functional monomer and photoinitiator 2959 to the prepolymer solution, wherein the ratio of chain extender, functional monomer and photoinitiator 2959 is 0.015 mol: 0.015 mol: 0.0005 mol; stir for 30 min to obtain a mixed solution;

[0031] (2) Pour the mixed solution into a PTFE mold and react it under ultraviolet light (365nm) for 25 min. Let it stand to defoam and then let it air dry naturally to form a film. After demolding, the tear-resistant polyurethane film is obtained.

[0032] The preparation process of the chain extender is as follows:

[0033]

[0034] 4-Pyridinecarboxaldehyde was added to a mixed solvent of 1,4-dioxane / water (v / v=1 / 1), followed by 2-hydroxypropyl 2-acrylate and a catalyst (triethylenediamine). The molar ratio of 4-pyridinecarboxaldehyde, 2-hydroxypropyl 2-acrylate, triethylenediamine, and the mixed solvent was 0.1 mol: 0.35 mol: 0.35 mol: 30 mL. The mixture was stirred for 45 h. After the reaction was completed, the reaction solution was washed with saturated brine, and the product was extracted with ethyl acetate. The ethyl acetate phase was concentrated, dried, filtered, and purified by silica gel column chromatography (eluent: ethyl acetate / n-hexane=40 / 60) to obtain the chain extender.

[0035] 1 H NMR (C 12 H 15NO4, 400 MHz, d6-DMSO) δ 8.63 (d, 2H), 7.48 (d, 2H), 6.60(s, 1H), 6.03 (s, 1H), 5.57 (s, 1H), 5.38 (s, 1H), 5.14 (s, 1H), 4.43-4.39(m, 1H), 4.30-4.26 (m, 1H), 4.17-4.14 (m, 1H), 1.15 (d, 3H); HRMS (ESI + ): [M+H] + The result is 238.10, and the value is 238.11.

[0036] The preparation process of the functional monomer is as follows:

[0037]

[0038] a. 2-Aminobenzoylhydrazine was added to N,N-dimethylformamide (DMF), followed by formamide and potassium hydroxide. The ratio of 2-aminobenzoylhydrazine, formamide, potassium hydroxide, and DMF was 0.1 mol: 0.18 mol: 0.18 mol: 90 mL. The mixture was refluxed for 3.5 h. After the reaction was completed, the reaction solution was diluted with water, and the product was extracted three times with ethyl acetate. The combined ethyl acetate phases were washed with water, dried, and concentrated to obtain the crude product. The crude product was recrystallized with methanol to obtain 2-(1H-1,2,4-triazol-5-yl)aniline.

[0039] b. The 2-(1H-1,2,4-triazol-5-yl)aniline was added to dichloromethane, followed by the addition of γ-thiobutyrolactone. The molar ratio of 2-(1H-1,2,4-triazol-5-yl)aniline, γ-thiobutyrolactone, and dichloromethane was 0.1 mol: 0.15 mol: 130 mL. The reaction was carried out at 40 °C for 22 h. After the reaction was completed, the reaction solution was washed successively with saturated sodium bicarbonate and deionized water. The organic phase was dried with anhydrous sodium sulfate and then purified by concentration and silica gel column chromatography (eluent: ethyl acetate / petroleum ether = 30 / 70) to obtain the functional monomer.

[0040] 1 H NMR (C 12 H 14N4OS, 400 MHz, d6-DMSO) δ 12.91 (s, 1H), 10.02 (s, 1H), 8.31 (s, 1H), 7.87-7.85 (d, 1H), 7.55-7.49 (m, 2H), 7.35-7.32 (t, 1H), 2.70(s, 1H), 2.55-2.52 (t, 2H), 2.40-2.37 (t, 2H), 1.99-1.96 (m, 2H); HRMS (ESI + ): [M+H] + The calculation yields 263.09, and the result is 263.08.

[0041] This embodiment 1 also provides a tear-resistant polyurethane film, which is prepared using the above-described preparation method.

[0042] Example 2

[0043] A method for preparing a tear-resistant polyurethane film includes the following steps:

[0044] (1) Before use, the macromolecular diol (polypropylene glycol, number average molecular weight of 600) was dehydrated under vacuum at 100℃ for 2 h. Then, the dehydrated macromolecular diol and diisocyanate (diphenylmethane diisocyanate) were added to acetone. The ratio of macromolecular diol, diisocyanate (diphenylmethane diisocyanate), and acetone was 0.01 mol: 0.02 mol: 50 mL. The mixture was stirred and reacted at 80℃ under an inert gas atmosphere for 3 h. Then, the temperature was lowered to 25℃, and a certain amount of acetone was added to adjust the viscosity. When adjusting the viscosity, the ratio of acetone to macromolecular diol was 150 mL: 0.01 mol. Then, a chain extender and an organotin catalyst (dibutyltin dilaurate) were added. The ratio of macromolecular diol, chain extender, and dibutyltin dilaurate was 0.01 mol: 0.01 mol: 3 μL. The temperature was raised to 80℃ and the reaction was carried out for 5 h. h, to obtain a prepolymer solution; cool to 25°C, add functional monomer and photoinitiator 2959 to the prepolymer solution, wherein the ratio of chain extender, functional monomer and photoinitiator 2959 is 0.01mol:0.01mol:0.0001mol; stir for 30 min to obtain a mixed solution;

[0045] (2) Pour the mixed solution into a PTFE mold, react it under ultraviolet light (365nm) for 20 min, let it stand to defoam, and then let it air dry naturally to form a film. After demolding, the tear-resistant polyurethane film is obtained.

[0046] The preparation process of the chain extender is as follows:

[0047] 4-Pyridinecarboxaldehyde was added to a mixed solvent of 1,4-dioxane / water (v / v=1 / 1), followed by 2-hydroxypropyl acrylate and a catalyst (triethylenediamine). The molar ratio of 4-pyridinecarboxaldehyde, 2-hydroxypropyl acrylate, triethylenediamine, and the mixed solvent was 0.1 mol:0.3 mol:0.3 mol:30 mL. The mixture was stirred for 40 h. After the reaction, the reaction solution was washed with saturated brine, and the product was extracted with ethyl acetate. The ethyl acetate phase was concentrated, dried, filtered, and purified by silica gel column chromatography (eluent: ethyl acetate / n-hexane=40 / 60) to obtain the chain extender. 1 H NMR and HRMS (ESI) + The characterization results are the same as in Example 1.

[0048] The preparation process of the functional monomer is as follows:

[0049] a. Add 2-aminobenzoyl hydrazide to DMF, then add formamide and potassium hydroxide. The ratio of 2-aminobenzoyl hydrazide, formamide, potassium hydroxide and DMF is 0.1 mol: 0.15 mol: 0.15 mol: 80 mL. Reflux for 3 h. After the reaction is complete, dilute the reaction solution with water, extract the product three times with ethyl acetate, and wash the combined ethyl acetate phases with water, dry and concentrate to obtain the crude product. Recrystallize the crude product with methanol to obtain 2-(1H-1,2,4-triazol-5-yl)aniline.

[0050] b. The 2-(1H-1,2,4-triazol-5-yl)aniline was added to dichloromethane, followed by the addition of γ-thiobutyrolactone. The molar ratio of 2-(1H-1,2,4-triazol-5-yl)aniline, γ-thiobutyrolactone, and dichloromethane was 0.1 mol:0.1 mol:100 mL. The reaction was carried out at 35 °C for 24 h. After the reaction was completed, the reaction solution was washed successively with saturated sodium bicarbonate and deionized water. The organic phase was dried over anhydrous sodium sulfate, then concentrated and purified by silica gel column chromatography (eluent: ethyl acetate / petroleum ether = 30 / 70) to obtain the functional monomer. 1 H NMR and HRMS (ESI) + The characterization results are the same as in Example 1.

[0051] This embodiment 2 also provides a tear-resistant polyurethane film, which is prepared using the above-described preparation method.

[0052] Example 3

[0053] A method for preparing a tear-resistant polyurethane film includes the following steps:

[0054] (1) Before use, the macromolecular diol (polyethylene glycol, number average molecular weight of 1500) was vacuum dehydrated at 105℃ for 1.5h. Then, the dehydrated macromolecular diol and diisocyanate (hexamethylene diisocyanate) were added to acetone. The ratio of macromolecular diol, diisocyanate (hexamethylene diisocyanate), and acetone was 0.02 mol: 0.05 mol: 70 mL. The mixture was stirred and reacted at 90℃ for 2 h under an inert gas atmosphere. Then, the temperature was lowered to 45℃, and a certain amount of acetone was added to adjust the viscosity. When adjusting the viscosity, the ratio of acetone to macromolecular diol was 200 mL: 0.02 mol. Then, a chain extender and an organotin catalyst (dibutyltin dilaurate) were added. The ratio of macromolecular diol, chain extender, and dibutyltin dilaurate was 0.02 mol: 0.02 mol: 9 μL. The temperature was raised to 90℃ and the reaction was carried out for 4 h. h, to obtain a prepolymer solution; cool to 45°C, add functional monomer and photoinitiator 2959 to the prepolymer solution, wherein the ratio of chain extender, functional monomer and photoinitiator 2959 is 0.02mol:0.02mol:0.001mol; stir for 30 min to obtain a mixed solution;

[0055] (2) Pour the mixed solution into a PTFE mold, react it under ultraviolet light (365nm) for 30 min, let it stand to defoam, and then let it air dry naturally to form a film. After demolding, the tear-resistant polyurethane film is obtained.

[0056] The preparation process of the chain extender is as follows:

[0057] 4-Pyridinecarboxaldehyde was added to a mixed solvent of 1,4-dioxane / water (v / v=1 / 1), followed by 2-hydroxypropyl acrylate and a catalyst (triethylenediamine). The molar ratio of 4-pyridinecarboxaldehyde, 2-hydroxypropyl acrylate, triethylenediamine, and the mixed solvent was 0.1 mol:0.4 mol:0.4 mol:30 mL. The mixture was stirred for 48 h. After the reaction, the reaction solution was washed with saturated brine, and the product was extracted with ethyl acetate. The ethyl acetate phase was concentrated, dried, filtered, and purified by silica gel column chromatography (eluent: ethyl acetate / n-hexane=40 / 60) to obtain the chain extender. 1 H NMR and HRMS (ESI) + The characterization results are the same as in Example 1.

[0058] The preparation process of the functional monomer is as follows:

[0059] a. Add 2-aminobenzoylhydrazine to N,N-dimethylformamide (DMF), then add formamide and potassium hydroxide. The ratio of 2-aminobenzoylhydrazine, formamide, potassium hydroxide, and DMF is 0.1 mol: 0.2 mol: 0.2 mol: 100 mL. Reflux for 4 h. After the reaction is complete, dilute the reaction solution with water, extract the product three times with ethyl acetate, and wash the combined ethyl acetate phases with water, dry, and concentrate to obtain the crude product. Recrystallize the crude product with methanol to obtain 2-(1H-1,2,4-triazol-5-yl)aniline.

[0060] b. The 2-(1H-1,2,4-triazol-5-yl)aniline was added to dichloromethane, followed by the addition of γ-thiobutyrolactone. The molar ratio of 2-(1H-1,2,4-triazol-5-yl)aniline, γ-thiobutyrolactone, and dichloromethane was 0.1 mol:0.2 mol:150 mL. The reaction was carried out at 45 °C for 20 h. After the reaction was completed, the reaction solution was washed successively with saturated sodium bicarbonate and deionized water. The organic phase was dried over anhydrous sodium sulfate, then concentrated and purified by silica gel column chromatography (eluent: ethyl acetate / petroleum ether = 30 / 70) to obtain the functional monomer. 1 H NMR and HRMS (ESI) + The characterization results are the same as in Example 1.

[0061] This embodiment 3 also provides a tear-resistant polyurethane film, which is prepared using the above-described preparation method.

[0062] Comparative Example 1

[0063] Comparative Example 1 is basically the same as Example 1, except that the chain extender is replaced with conventional chain extender ethylene glycol, while the rest is the same as Example 1.

[0064] Comparative Example 2

[0065] Comparative Example 2 is basically the same as Example 1, except that the functional monomer is replaced with 2-(1H-1,2,4-triazol-5-yl)aniline, while the rest is the same as Example 1.

[0066] Performance testing

[0067] 1. The tear strength of Examples 1-3 and Comparative Examples 1-2 of this invention was tested according to GB / T529-2008 "Determination of tear strength of vulcanized rubber or thermoplastic rubber".

[0068] 2. The tensile strength and elongation at break of Examples 1-3 and Comparative Examples 1-2 of this invention were tested according to GB / T528-2009 "Determination of Tensile Stress-Strain Properties of Vulcanized Rubber or Thermoplastic Rubber". The test results are shown in Table 1.

[0069] Table 1

[0070]

[0071] As can be seen from the test data in Table 1, the polyurethane films obtained in Examples 1-3 of the present invention have good tear resistance and mechanical properties, specifically exhibiting excellent tear strength, tensile strength and elongation at break.

[0072] Compared with Example 1, Comparative Example 1 replaced the chain extender with conventional chain extender ethylene glycol, and Comparative Example 2 replaced the functional monomer with 2-(1H-1,2,4-triazol-5-yl)aniline. Experimental results showed that the tear strength, tensile strength, and elongation at break of the polyurethane films obtained in both examples decreased, indicating that the chain extender and functional monomer designed in this invention have significant advantages in improving the mechanical properties of polyurethane films. The chain extender prepared in this invention is more effective than ethylene glycol in improving the mechanical properties of polyurethane films because the pyridine ring and acrylate double bond introduced into the chain extender structure of this invention can not only enhance the intermolecular forces through covalent crosslinking but also effectively improve tear resistance while maintaining the material's flexibility. On the other hand, the functional monomer described in this invention can be covalently bonded to the polyurethane network, and the triazole ring in its molecule can form strong hydrogen bond interactions with the hard segments of polyurethane; at the same time, since the polarity of the triazole ring is similar to that of the urethane group, the monomer has good compatibility with the polyurethane matrix, which promotes the orderly arrangement of the hard segment region and microphase separation, thereby synergistically improving the tear resistance, tensile strength and elongation at break of the material.

[0073] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. The basic principles and main features of the present invention have been described above with specific implementation schemes. Based on the present invention, some modifications or substitutions can be made, but these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of protection claimed by the present invention.

Claims

1. A method for preparing a tear-resistant polyurethane film, characterized in that, Includes the following steps: (1) Add macromolecular diol and diisocyanate to acetone and stir under an inert gas atmosphere; after the reaction, add acetone to adjust the viscosity, then add chain extender and organotin catalyst, heat to react, and obtain a prepolymer solution; add functional monomer and photoinitiator to the prepolymer solution, stir, and obtain a mixed solution. (2) Pour the mixed solution into the mold, react under ultraviolet light, let it stand to defoam, and then let it air dry naturally to form a film. After demolding, a tear-resistant polyurethane film is obtained. The preparation process of the chain extender mentioned in step (1) is as follows: 4-Pyridinecarboxaldehyde was added to a solvent, followed by 2-hydroxypropyl 2-acrylate and a catalyst, and the mixture was stirred to react. After the reaction was completed, the chain extender was obtained by extraction, concentration, drying, filtration, and purification. The preparation process of the functional monomer mentioned in step (1) is as follows: a. Add 2-aminobenzoylhydrazine to a solvent, then add formamide and potassium hydroxide and reflux. After the reaction is complete, extract, wash, dry and concentrate the reaction solution to obtain a crude product. Recrystallize to obtain 2-(1H-1,2,4-triazol-5-yl)aniline. b. Add the 2-(1H-1,2,4-triazol-5-yl)aniline to a solvent, and then add γ-thiobutyrolactone to react; after the reaction is completed, wash, dry, concentrate and purify the reaction solution to obtain the functional monomer.

2. The method for preparing the tear-resistant polyurethane film according to claim 1, characterized in that, The ratio of 4-pyridinecarboxaldehyde, 2-hydroxypropyl acrylate, catalyst, and solvent is 0.1 mol: 0.3-0.4 mol: 0.3-0.4 mol: 30 mL; the solvent is prepared by mixing 1,4-dioxane and water in equal volumes; the catalyst is triethylenediamine; and the stirring reaction time is 40-48 h.

3. The method for preparing the tear-resistant polyurethane film according to claim 1, characterized in that, In step a, the ratio of 2-aminobenzoyl hydrazide, formamide, potassium hydroxide, and solvent is 0.1 mol: 0.15-0.2 mol: 0.15-0.2 mol: 80-100 mL; the solvent is N,N-dimethylformamide; and the reflux reaction time is 3-4 h.

4. The method for preparing the tear-resistant polyurethane film according to claim 1, characterized in that, In step b, the ratio of 2-(1H-1,2,4-triazol-5-yl)aniline, γ-thiobutyrolactone, and solvent is 0.1 mol: 0.1-0.2 mol: 100-150 mL; the solvent is dichloromethane; the reaction temperature is 35-45℃, and the reaction time is 20-24 h.

5. The method for preparing the tear-resistant polyurethane film according to claim 1, characterized in that, In step (1), during the stirring reaction, the ratio of macromolecular diol, diisocyanate, and acetone is 0.01-0.02 mol: 0.02-0.05 mol: 50-70 mL; the ratio of macromolecular diol, chain extender, organotin catalyst, functional monomer, and photoinitiator is 0.01-0.02 mol: 0.01-0.02 mol: 3-9 μL: 0.01-0.02 mol: 0.0001-0.001 mol.

6. The method for preparing the tear-resistant polyurethane film according to claim 1, characterized in that, In step (1), the temperature of the stirring reaction is 80-90℃ and the time is 2-3h; the temperature of the heating reaction is 80-90℃ and the time is 4-5h; in step (2), the wavelength of the ultraviolet lamp is 360-370nm and the reaction time is 20-30min.

7. The method for preparing the tear-resistant polyurethane film according to claim 1, characterized in that, In step (1), the macromolecular diol is vacuum dehydrated at 100-105℃ for 1.5-2 h before use; when adjusting the viscosity, the ratio of acetone to macromolecular diol is 150-200 mL: 0.01-0.02 mol; the temperature when adding acetone is 25-45℃; the temperature when adding functional monomers and photoinitiators is 25-45℃. The macromolecular diol is selected from either polyethylene glycol or polypropylene glycol, with a number average molecular weight of 600-1500; the diisocyanate is selected from either toluene diisocyanate, diphenylmethane diisocyanate, or hexamethylene diisocyanate; the organotin catalyst is dibutyltin dilaurate; and the photoinitiator is photoinitiator 2959.

8. A tear-resistant polyurethane film, characterized in that, It is prepared according to any one of claims 1-7.

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