A hyperbranched polyurethane with high tensile strength and its preparation method

Abstract

This invention relates to the field of polyurethane technology and discloses a high-tensile-strength hyperbranched polyurethane and its preparation method. Maleic anhydride-grafted POE undergoes acylation and ring-opening with a hydroxyethylamine-p-aminotriazine compound to obtain a polyhydroxytriazine crosslinked POE. Isophorone diisocyanate is first reacted with polypropylene carbonate diol, and then reacted with the polyhydroxytriazine crosslinked POE to obtain a high-tensile-strength hyperbranched polyurethane. The polyhydroxytriazine crosslinked POE prepared by this invention contains numerous reaction sites, which, upon reaction with the prepolymer, can increase the degree of crosslinking. It also contains unreacted hydroxyl and amino groups, forming intermolecular hydrogen bonds. Furthermore, the maleic anhydride-grafted POE elastomer can absorb a large amount of impact energy, further improving the tensile strength and other mechanical properties of the hyperbranched polyurethane.

Description

Technical Field

[0001] This invention relates to the field of polyurethane technology, specifically to a hyperbranched polyurethane with high tensile strength and its preparation method. Background Technology

[0002] Polyurethane is a polymer material obtained by polymerization of isocyanate and polyol. Traditional polyurethane suffers from poor mechanical properties, such as tensile strength, making the improvement of its mechanical properties a current research hotspot. Hyperbranched polyurethane is a derivative of polyurethane, possessing high molecular weight and molecular weight distribution, abundant end groups, low viscosity, and excellent adhesion, and is widely used in coatings, adhesives, inks, binders, resins, and other fields. Patent application CN113105608A discloses a self-healing hyperbranched polyurethane with high mechanical strength, its preparation method, and its applications. The method involves reacting polytetrahydrofuran, N-(4-hydroxy-3-methylphenylmethylene)-p-hydroxyaniline (VA), and isophorone diisocyanate to obtain an isocyanate-terminated polyurethane prepolymer, which is then reacted with hyperbranched polyester, triaminopyridine, and tannic acid to obtain a hydrogen-bonded self-healing crosslinked polyurethane. This invention utilizes the reaction of hyperbranched polyester with isocyanate-terminated prepolymer to prepare a polyurethane with high mechanical strength, but it suffers from generally poor tensile strength. The present invention prepares a novel polyhydroxytriazine crosslinked POE with more reaction sites, which increases the degree of crosslinking when reacting with polyurethane prepolymer, thereby improving the tensile strength and other mechanical properties of hyperbranched polyurethane. Summary of the Invention

[0003] (a) Technical problems to be solved

[0004] To address the shortcomings of existing technologies, this invention provides a hyperbranched polyurethane with high tensile strength and its preparation method. The prepared hyperbranched polyurethane exhibits excellent mechanical properties such as tensile strength.

[0005] (II) Technical Solution

[0006] A method for preparing hyperbranched polyurethane with high tensile strength, the method being as follows:

[0007] (1) Preparation method of hydroxyethylamine p-nitrotriazine

[0008] 6-(N,N-dihydroxyethyl)amino-2,4-dichloro-1,3,5-triazine was dissolved in acetone and stirred until dissolved. p-Nitroaniline and sodium carbonate were added to the solution at 20-35°C, and the mixture was stirred for 5-10 hours. The solution was then filtered, washed with water, and dried under vacuum to obtain the hydroxyethylamine-p-nitrotriazine intermediate.

[0009] (2) Preparation method of hydroxyethylamine p-aminotriazine compound

[0010] Zinc powder was added to a 5-20% (w / w) acetic acid solution and stirred until homogeneous. Then, the hydroxyethylamine-p-nitrotriazine intermediate was added and the mixture was stirred to react. After the reaction was complete, the mixture was cooled to room temperature, and sodium hydroxide solution was added to adjust the pH to 8-9. The mixture was then heated and filtered while hot, washed with hot water, and recrystallized from ethanol to obtain the hydroxyethylamine-p-aminotriazine compound. The preparation route of the hydroxyethylamine-p-aminotriazine compound is as follows:

[0011]

[0012] (3) Preparation method of polyhydroxytriazine crosslinked POE

[0013] Maleic anhydride-grafted POE was dissolved in N,N-dimethylformamide solution at 20-35℃ and stirred until homogeneous. Sodium hydroxide solution was added dropwise to adjust the pH to 9-10. Hydroxyethylamine-p-aminotriazine compound was then added and the mixture was stirred at room temperature for 3-6 hours. After the reaction was completed, the mixture was filtered and dried to obtain polyhydroxytriazine crosslinked POE.

[0014] (4) Preparation method of hyperbranched polyurethane

[0015] Isophorone diisocyanate and polypropylene carbonate diol were stirred and reacted at 75-95℃ for 2-4 hours to obtain NCO-terminated polyurethane prepolymer. N,N-dimethylformamide solution of polyhydroxytriazine crosslinked POE was added to the NCO-terminated polyurethane prepolymer and the reaction was stirred continuously. After the reaction was completed, the mixture was filtered, washed with ethanol, dried, and aged at room temperature for 48-72 hours to obtain hyperbranched polyurethane with high tensile strength.

[0016] Specifically, in step (1), the molar amounts of p-nitroaniline and sodium carbonate are (100-120)% and (40-60)% of the molar amounts of 6-(N,N-dihydroxyethyl)amino-2,4-dichloro-1,3,5-triazine, respectively.

[0017] Specifically, the molar amount of zinc powder used in step (2) is (550-650) of hydroxyethylamine p-nitrotriazine.

[0018] Specifically, in step (2), the stirring reaction time is 5-10 hours and the temperature is 75-90℃.

[0019] Specifically, in step (3), the mass of hydroxyethylamine p-aminotriazine is 4-15% of the mass of maleic anhydride grafted with POE.

[0020] Specifically, in step (4), the molar amount of isophorone diisocyanate is (220-310) of the molar amount of polypropylene carbonate diol.

[0021] Specifically, in step (4), the mass of the polyhydroxytriazine crosslinked POE is 2-15% of that of the NCO-terminated polyurethane prepolymer.

[0022] Specifically, in step (4), the continuous stirring reaction temperature is 80-90℃ and the continuous stirring reaction time is 4-8h.

[0023] (iii) Beneficial technical effects

[0024] 6-(N,N-dihydroxyethyl)amino-2,4-dichloro-1,3,5-triazine undergoes a substitution reaction with p-nitroaniline to give a hydroxyethylamine-p-nitrotriazine intermediate. The product is then reduced under zinc powder conditions to give a hydroxyethylamine-p-aminotriazine compound. In a sodium hydroxide alkaline system, maleic anhydride-grafted POE undergoes acylation and ring-opening with the hydroxyethylamine-p-aminotriazine compound to give a polyhydroxytriazine crosslinked POE. Isophorone diisocyanate is first reacted with polypropylene carbonate diol to give an NCO-terminated polyurethane prepolymer, which is then reacted with the polyhydroxytriazine crosslinked POE to obtain a hyperbranched polyurethane with high tensile strength.

[0025] The polyhydroxytriazine crosslinked POE prepared in this invention contains a large number of highly active hydroxyl groups at its ends, providing numerous active sites for reaction with the prepolymer, thus increasing the degree of crosslinking. Furthermore, the presence of numerous branching points within the polymer molecule creates significant steric hindrance, making chain segment slippage less likely. Additionally, the presence of unreacted hydroxyl and amino groups facilitates the formation of intramolecular and intermolecular hydrogen bonds, resulting in strong intermolecular forces and improved tensile strength and other mechanical properties of the polyurethane. The maleic anhydride-grafted POE used in this invention exhibits good compatibility with the matrix, and under external forces, the maleic anhydride-grafted POE elastomer can absorb a significant amount of impact energy, further enhancing the material's mechanical properties. Therefore, the hyperbranched polyurethane prepared in this invention possesses excellent tensile strength and other mechanical properties. Detailed Implementation

[0026] For the purpose of promoting an understanding of the principles of this disclosure, reference will now be made to embodiments, and the principles of this disclosure will be described using specific language. However, it should be understood that this is not intended to limit the scope of this disclosure, and such modifications and further alterations to the disclosed compositions and methods, as well as such further applications of the principles of this disclosure, are considered to be common knowledge to those skilled in the art to which this disclosure pertains.

[0027] Throughout this specification, references to "an embodiment," "embodiment," or similar language mean that a particular feature, structure, or characteristic described in connection with an embodiment is included in at least one embodiment of this disclosure. Therefore, the phrases "in one embodiment," "in an embodiment," and similar language throughout this specification may (but not necessarily) all refer to the same embodiment.

[0028] Example 1

[0029] (1) Preparation method of hydroxyethylamine p-nitrotriazine

[0030] 6 mol of 6-(N,N-dihydroxyethyl)amino-2,4-dichloro-1,3,5-triazine was dissolved in acetone and stirred until dissolved. 7 mol of p-nitroaniline and 3 mol of sodium carbonate were added to the solution at 35 °C. The mixture was stirred for 5 h, filtered, washed with water, and dried under vacuum to obtain the hydroxyethylamine-p-nitrotriazine intermediate.

[0031] (2) Preparation method of hydroxyethylamine p-aminotriazine compound

[0032] 12 mol of zinc powder was added to a 15% acetic acid solution and stirred until homogeneous. Then, 2 mol of hydroxyethylamine p-nitrotriazine intermediate was added. The mixture was stirred at 90°C for 5 hours. After the reaction was completed, the mixture was cooled to room temperature, and sodium hydroxide solution was added to adjust the pH to 9. The mixture was then heated and filtered while hot, washed with hot water, and recrystallized from ethanol to obtain the hydroxyethylamine p-aminotriazine compound.

[0033] (3) Preparation method of polyhydroxytriazine crosslinked POE

[0034] At 20°C, 20g of maleic anhydride-grafted POE was dissolved in N,N-dimethylformamide solution and stirred until homogeneous. Sodium hydroxide solution was added dropwise to adjust the pH to 10. 2g of hydroxyethylamine p-aminotriazine compound was added to the solution and the mixture was stirred at room temperature for 5 hours. After the reaction was completed, the mixture was filtered and dried to obtain polyhydroxytriazine crosslinked POE.

[0035] (4) Preparation method of hyperbranched polyurethane

[0036] At 80℃, 1.2 mol of isophorone diisocyanate and 0.4 mol of polypropylene carbonate diol were stirred and reacted for 4 h to obtain NCO-terminated polyurethane prepolymer. 150 g of NCO-terminated polyurethane prepolymer was weighed and N,N-dimethylformamide solution containing 3 g of polyhydroxytriazine crosslinked POE was added. The mixture was stirred and reacted continuously at 85℃ for 8 h. After the reaction was completed, the mixture was filtered, washed with ethanol, dried, and aged at room temperature for 48 h to obtain hyperbranched polyurethane with high tensile strength.

[0037] Example 2

[0038] (1) Preparation method of hydroxyethylamine p-nitrotriazine

[0039] 6 mol of 6-(N,N-dihydroxyethyl)amino-2,4-dichloro-1,3,5-triazine was dissolved in acetone and stirred until dissolved. 7 mol of p-nitroaniline and 3 mol of sodium carbonate were added to the solution at 30 °C. The mixture was stirred for 8 h, filtered, washed with water, and dried under vacuum to obtain the hydroxyethylamine-p-nitrotriazine intermediate.

[0040] (2) Preparation method of hydroxyethylamine p-aminotriazine compound

[0041] 12 mol of zinc powder was added to a 15% acetic acid solution and stirred until homogeneous. Then, 2 mol of hydroxyethylamine p-nitrotriazine intermediate was added. The mixture was stirred at 80°C for 8 hours. After the reaction was completed, the mixture was cooled to room temperature, and sodium hydroxide solution was added to adjust the pH to 9. The mixture was then heated and filtered while hot, washed with hot water, and recrystallized from ethanol to obtain the hydroxyethylamine p-aminotriazine compound.

[0042] (3) Preparation method of polyhydroxytriazine crosslinked POE

[0043] At 20°C, 20g of maleic anhydride-grafted POE was dissolved in N,N-dimethylformamide solution and stirred until homogeneous. Sodium hydroxide solution was added dropwise to adjust the pH to 10. 2g of hydroxyethylamine p-aminotriazine compound was added to the solution and the mixture was stirred at room temperature for 5 hours. After the reaction was completed, the mixture was filtered and dried to obtain polyhydroxytriazine crosslinked POE.

[0044] (4) Preparation method of hyperbranched polyurethane

[0045] At 80°C, 1.2 mol of isophorone diisocyanate and 0.4 mol of polypropylene carbonate diol were stirred and reacted for 3 h to obtain NCO-terminated polyurethane prepolymer. 150 g of NCO-terminated polyurethane prepolymer was weighed and N,N-dimethylformamide solution containing 8 g of polyhydroxytriazine crosslinked POE was added. The mixture was stirred and reacted at 90°C for 4 h. After the reaction was completed, the mixture was filtered, washed with ethanol, dried, and aged at room temperature for 72 h to obtain hyperbranched polyurethane with high tensile strength.

[0046] Example 3

[0047] (1) Preparation method of hydroxyethylamine p-nitrotriazine

[0048] 6 mol of 6-(N,N-dihydroxyethyl)amino-2,4-dichloro-1,3,5-triazine was dissolved in acetone and stirred until dissolved. 7 mol of p-nitroaniline and 3 mol of sodium carbonate were added to the solution at 30 °C. The mixture was stirred for 8 h, filtered, washed with water, and dried under vacuum to obtain the hydroxyethylamine-p-nitrotriazine intermediate.

[0049] (2) Preparation method of hydroxyethylamine p-aminotriazine compound

[0050] 12 mol of zinc powder was added to a 20% acetic acid solution and stirred until homogeneous. Then, 2 mol of hydroxyethylamine p-nitrotriazine intermediate was added. The mixture was stirred at 80°C for 8 hours. After the reaction was completed, the mixture was cooled to room temperature, and sodium hydroxide solution was added to adjust the pH to 9. The mixture was then heated and filtered while hot, washed with hot water, and recrystallized from ethanol to obtain the hydroxyethylamine p-aminotriazine compound.

[0051] (3) Preparation method of polyhydroxytriazine crosslinked POE

[0052] At 20°C, 20g of maleic anhydride-grafted POE was dissolved in N,N-dimethylformamide solution and stirred until homogeneous. Sodium hydroxide solution was added dropwise to adjust the pH to 10. 2g of hydroxyethylamine p-aminotriazine compound was added to the solution and the mixture was stirred at room temperature for 4 hours. After the reaction was completed, the mixture was filtered and dried to obtain polyhydroxytriazine crosslinked POE.

[0053] (4) Preparation method of hyperbranched polyurethane

[0054] At 90℃, 1.2 mol of isophorone diisocyanate and 0.4 mol of polypropylene carbonate diol were stirred and reacted for 3 h to obtain NCO-terminated polyurethane prepolymer. 150 g of NCO-terminated polyurethane prepolymer was weighed and 13 g of N,N-dimethylformamide solution of polyhydroxytriazine crosslinked POE was added to it. The mixture was stirred and reacted continuously at 85℃ for 5 h. After the reaction was completed, the mixture was filtered, washed with ethanol, dried, and aged at room temperature for 72 h to obtain hyperbranched polyurethane with high tensile strength.

[0055] Example 4

[0056] (1) Preparation method of hydroxyethylamine p-nitrotriazine

[0057] 6 mol of 6-(N,N-dihydroxyethyl)amino-2,4-dichloro-1,3,5-triazine was dissolved in acetone and stirred until dissolved. 7.2 mol of p-nitroaniline and 3 mol of sodium carbonate were added to the solution at 20 °C. The mixture was stirred for 8 h, filtered, washed with water, and dried under vacuum to obtain the hydroxyethylamine-p-nitrotriazine intermediate.

[0058] (2) Preparation method of hydroxyethylamine p-aminotriazine compound

[0059] 12 mol of zinc powder was added to a 15% acetic acid solution and stirred until homogeneous. Then, 2 mol of hydroxyethylamine p-nitrotriazine intermediate was added. The mixture was stirred at 80°C for 8 hours. After the reaction was completed, the mixture was cooled to room temperature, and sodium hydroxide solution was added to adjust the pH to 9. The mixture was then heated and filtered while hot, washed with hot water, and recrystallized from ethanol to obtain the hydroxyethylamine p-aminotriazine compound.

[0060] (3) Preparation method of polyhydroxytriazine crosslinked POE

[0061] At 30°C, 20g of maleic anhydride-grafted POE was dissolved in N,N-dimethylformamide solution and stirred until homogeneous. Sodium hydroxide solution was added dropwise to adjust the pH to 10. 0.8g of hydroxyethylamine p-aminotriazine compound was added to the solution and the mixture was stirred at room temperature for 4 hours. After the reaction was completed, the mixture was filtered and dried to obtain polyhydroxytriazine crosslinked POE.

[0062] (4) Preparation method of hyperbranched polyurethane

[0063] At 90℃, 1.2 mol of isophorone diisocyanate and 0.4 mol of polypropylene carbonate diol were stirred and reacted for 3 h to obtain NCO-terminated polyurethane prepolymer. 150 g of NCO-terminated polyurethane prepolymer was weighed and 18 g of N,N-dimethylformamide solution of polyhydroxytriazine crosslinked POE was added. The mixture was stirred and reacted continuously at 85℃ for 8 h. After the reaction was completed, the mixture was filtered, washed with ethanol, dried, and aged at room temperature for 72 h to obtain hyperbranched polyurethane with high tensile strength.

[0064] Example 5

[0065] (1) Preparation method of hydroxyethylamine p-nitrotriazine

[0066] 6 mol of 6-(N,N-dihydroxyethyl)amino-2,4-dichloro-1,3,5-triazine was dissolved in acetone and stirred until dissolved. 7 mol of p-nitroaniline and 3 mol of sodium carbonate were added to the solution at 30 °C. The mixture was stirred for 10 h, filtered, washed with water, and dried under vacuum to obtain the hydroxyethylamine-p-nitrotriazine intermediate.

[0067] (2) Preparation method of hydroxyethylamine p-aminotriazine compound

[0068] 12 mol of zinc powder was added to a 15% acetic acid solution and stirred until homogeneous. Then, 2 mol of hydroxyethylamine p-nitrotriazine intermediate was added. The mixture was stirred at 80°C for 8 hours. After the reaction was completed, the mixture was cooled to room temperature, and sodium hydroxide solution was added to adjust the pH to 9. The mixture was then heated and filtered while hot, washed with hot water, and recrystallized from ethanol to obtain the hydroxyethylamine p-aminotriazine compound.

[0069] (3) Preparation method of polyhydroxytriazine crosslinked POE

[0070] At 30°C, 20g of maleic anhydride-grafted POE was dissolved in N,N-dimethylformamide solution and stirred until homogeneous. Sodium hydroxide solution was added dropwise to adjust the pH to 10. 0.8g of hydroxyethylamine p-aminotriazine compound was added to the solution and the mixture was stirred at room temperature for 5 hours. After the reaction was completed, the mixture was filtered and dried to obtain polyhydroxytriazine crosslinked POE.

[0071] (4) Preparation method of hyperbranched polyurethane

[0072] At 80℃, 1.2 mol of isophorone diisocyanate and 0.4 mol of polypropylene carbonate diol were stirred and reacted for 3 h to obtain NCO-terminated polyurethane prepolymer. 150 g of NCO-terminated polyurethane prepolymer was weighed and N,N-dimethylformamide solution containing 22.5 g of polyhydroxytriazine crosslinked POE was added to it. The mixture was stirred and reacted continuously at 85℃ for 5 h. After the reaction was completed, the mixture was filtered, washed with ethanol, dried, and aged at room temperature for 72 h to obtain hyperbranched polyurethane with high tensile strength.

[0073] Comparative Example 1

[0074] Preparation method of polyurethane materials

[0075] At 80℃, 1.2 mol of isophorone diisocyanate and 0.4 mol of polypropylene carbonate diol were stirred and reacted for 3 h to obtain NCO-terminated polyurethane prepolymer. 150 g of NCO-terminated polyurethane prepolymer was weighed and an acetone solution containing 6.2 g of 1,4-butanediol was added to it. The mixture was stirred and reacted continuously at 55℃ for 5 h. After the reaction was completed, the mixture was filtered, washed with ethanol, dried, and aged at room temperature for 72 h to obtain polyurethane material.

[0076] Tensile properties were tested using a universal testing machine at a tensile rate of 200 mm / min.

[0077]

[0078] The hyperbranched polyurethanes of Examples 1-5 exhibit better tensile properties than those of Comparative Example 1. This is because polyhydroxytriazine crosslinked POE was added in Examples 1-5, which has more hydroxyl active reaction sites, increasing the degree of crosslinking and mechanical properties. Furthermore, since the prepared polyhydroxytriazine crosslinked POE contains POE elastomer, it can absorb more tensile force during stretching, further enhancing the tensile properties of the hyperbranched polyurethane. Comparative Example 1 did not contain these components. Therefore, the hyperbranched polyurethane prepared by this invention has excellent tensile properties.

[0079] According to GB / T6669-2008, the compressive permanent deformation of the test material is measured.

[0080] According to ASTM D955-2008 (2014), the shrinkage rate of the material is tested.

[0081]

[0082] The hyperbranched polyurethane material of Example 4 exhibited the lowest compression set, while the hyperbranched polyurethane material of Example 3 showed the lowest shrinkage. The compression set and shrinkage properties of Examples 1-5 were better than those of the polyurethane material of Comparative Example 1. This is because the POE component in the hyperbranched polyurethanes of Examples 1-5 contained octene short branches. Copolymers composed of octene short branches have the best elasticity, and a large number of side groups intertwine to form a network structure. When subjected to impact, this network structure can dissipate external forces and improve the toughness of the material. Therefore, the compression set and shrinkage properties of the hyperbranched polyurethane materials of Examples 1-5 are superior to those of the polyurethane material of Comparative Example 1.

[0083] The above embodiments are merely illustrative of the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features. These modifications or substitutions do not cause the essence of the corresponding technical solutions to depart from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing high tensile strength hyperbranched polyurethane, characterized in that, The preparation method is as follows: (1) Preparation of polyhydroxytriazine crosslinked POE: Maleic anhydride-grafted POE was dissolved in N,N-dimethylformamide solution at 20-35℃ and stirred until homogeneous. Sodium hydroxide solution was added dropwise to adjust the pH to 9-10. Hydroxyethylamine p-aminotriazine compound was added to the solution and the mixture was stirred at room temperature for 3-6 hours. After the reaction was completed, the mixture was filtered and dried to obtain polyhydroxytriazine crosslinked POE. (2) Preparation of hyperbranched polyurethane: Isophorone diisocyanate and polypropylene carbonate diol were stirred and reacted at 75-95℃ for 2-4 hours to obtain NCO-terminated polyurethane prepolymer. N,N-dimethylformamide solution of polyhydroxytriazine crosslinked POE was added to the NCO-terminated polyurethane prepolymer and stirred continuously. After the reaction was completed, the mixture was filtered, washed with ethanol, dried, and aged at room temperature for 48-72 hours to obtain hyperbranched polyurethane with high tensile strength. In step (1), the mass of hydroxyethylamine p-aminotriazine is 4-15% of the maleic anhydride-grafted POE. The preparation method of the hydroxyethylamine-p-aminotriazine compound is as follows: (3) Preparation of hydroxyethylamine p-nitrotriazine: 6-(N,N-dihydroxyethyl)amino-2,4-dichloro-1,3,5-triazine was dissolved in acetone and stirred until dissolved. p-nitroaniline and sodium carbonate were added to the solution at 20-35°C and the mixture was stirred for 5-10 hours. The solution was then filtered, washed with water, and dried under vacuum to obtain the hydroxyethylamine-p-nitrotriazine intermediate. (4) Preparation of hydroxyethylamine-p-aminotriazine compounds: Zinc powder was added to an acetic acid solution with a mass fraction of 5-20%, and stirred until homogeneous. Then, hydroxyethylamine p-nitrotriazine intermediate was added and stirred to react. After the reaction was completed, the mixture was cooled to room temperature, and sodium hydroxide solution was added to adjust the pH to 8-9. The mixture was then heated and filtered while hot, washed with hot water, and recrystallized from ethanol to obtain the hydroxyethylamine p-aminotriazine compound.

2. The method for preparing high tensile strength hyperbranched polyurethane according to claim 1, characterized in that, In step (2), the molar amount of isophorone diisocyanate is (220-310) of the molar amount of polypropylene carbonate diol.

3. The method for preparing high tensile strength hyperbranched polyurethane according to claim 1, characterized in that, In step (2), the mass of the polyhydroxytriazine crosslinked POE is 2-15% of that of the NCO-terminated polyurethane prepolymer.

4. The method for preparing high tensile strength hyperbranched polyurethane according to claim 1, characterized in that, In step (2), the continuous stirring reaction temperature is 80-90℃, and the continuous stirring reaction time is 4-8h.

5. The method for preparing high tensile strength hyperbranched polyurethane according to claim 1, characterized in that, In step (3), the molar amounts of p-nitroaniline and sodium carbonate are (100-120)% and (40-60)% of the molar amounts of 6-(N,N-dihydroxyethyl)amino-2,4-dichloro-1,3,5-triazine, respectively.

6. The method for preparing high tensile strength hyperbranched polyurethane according to claim 1, characterized in that, In step (4), the molar amount of zinc powder is (550-650) of the hydroxyethylamine-p-nitrotriazine intermediate.

7. The method for preparing high tensile strength hyperbranched polyurethane according to claim 1, characterized in that, The stirring reaction time in step (4) is 5-10 hours and the temperature is 75-90℃.

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