A stretch self-reinforced topological cross-linked recyclable polyurea material, a preparation method and application thereof

Abstract

This invention discloses a tensile self-reinforced topologically crosslinked recyclable polyurea material and its preparation method. Polyurea is modified with a four-arm topological crosslinking agent containing dynamic imine bonds to construct a dynamic topological crosslinking network. The topological structure restricts molecular chain slippage, inducing molecular chain orientation and network reconstruction under tension, thus achieving tensile self-reinforcement of the material. The polyurea material of this invention exhibits an initial tensile strength of 31.29 MPa and a fracture toughness of 181.15 MJ / m. 3 After pre-stretching, the strength can be increased to 42.09 MPa, and the toughness can be increased to 202.26 MJ / m. 3 It also has excellent recyclability and can be widely used in building protection, impact resistance engineering, aerospace and other fields.

Description

Technical Field

[0001] This invention belongs to the field of polyurea material technology, specifically relating to a stretch-reinforced topological cross-linked recyclable polyurea material, its preparation method, and its application. Background Technology

[0002] Polyurea, with its advantages of flexible structural design, wide range of adjustable mechanical properties, excellent weather and corrosion resistance, and outstanding impact resistance, is widely used in various engineering fields such as building protection, marine corrosion protection, and aerospace. The mechanical strength of traditional linear polyurea mainly relies on the hydrogen bond network formed by urea bonds in the molecular chain, which cannot meet the requirements of high-load and long-life engineering applications. To solve this problem, the industry typically introduces multifunctional chain extenders to construct a permanently covalently cross-linked network, thereby improving the strength and creep resistance of polyurea. However, these permanently cross-linked thermosetting polyureas cannot be reprocessed or recycled, resulting in serious resource waste and environmental pollution after disposal, which is inconsistent with the green and sustainable development trend of polymer materials.

[0003] By introducing dynamic covalent bonds or dynamic non-covalent interactions into the polyurea system, the cross-linked network can undergo reversible fracture and reconstruction under external stimuli, thus endowing the material with recyclability while ensuring mechanical properties. However, there are currently few polyurea materials in the industry that can simultaneously achieve a synergistic improvement in high strength, high toughness, and recyclability, while also possessing tensile self-reinforcing properties.

[0004] Therefore, in order to solve the above problems, this invention designs a four-arm topological crosslinking agent containing dynamic imine bonds and introduces it into the polyurea system to construct a dynamic topological crosslinking network. This solves the industry problem of the trade-off between the strength and toughness of existing dynamic polyurea. It has important scientific significance and engineering application value for expanding the application scope of polyurea in high-end engineering fields and promoting the green and sustainable development of polymer protective materials. Summary of the Invention

[0005] The purpose of this invention is to provide a tensile self-reinforced topological crosslinked recyclable polyurea material, its preparation method, and its application. This polyurea material can simultaneously achieve high strength, high fracture toughness, and excellent closed-loop recyclability, while also possessing unique tensile self-reinforcing properties, as well as excellent water resistance and impact resistance. It can be widely used in fields such as building waterproofing and impact-resistant engineering protection.

[0006] The present invention achieves its objective by employing the following technical solution: a stretchable self-reinforced topological crosslinking recyclable polyurea material, wherein the polyurea material is a topological crosslinking network structure formed by addition polymerization of a tetra-arm imine topological crosslinking agent and a terminal isocyanate-based polyurea prepolymer; The four-armed imine topological crosslinking agent is a four-armed structure product prepared by condensation reaction of polyether triamine ZT-143 and terephthalaldehyde. The molecular chain contains dynamic reversible imine bonds, and the molecular ends have active amino groups that can participate in polyurea reactions. The molar ratio of polyether triamine ZT-143 to terephthalaldehyde is 2~2.1:1. The isocyanate-terminated polyurea prepolymer is obtained by the addition polymerization reaction of hexamethylene diisocyanate and polyetheramine D-400, wherein the molar ratio of hexamethylene diisocyanate to polyetheramine D-400 is 1:0.80~0.9.

[0007] The molecular structural formula of the aforementioned four-arm imine topological crosslinking agent is as follows:

[0008] The molar ratio of the aforementioned tetra-armed imine topological crosslinking agent and the terminal isocyanate-based polyurea prepolymer is 0.05~0.1:1.

[0009] The molar ratio of the aforementioned polyether triamine ZT-143 to terephthalaldehyde is 2:1.

[0010] The molar ratio of the aforementioned hexamethylene diisocyanate and polyetheramine D-400 is 1:0.80.

[0011] The aforementioned method for preparing a stretch-reinforced, topologically cross-linked, recyclable polyurea material is characterized by comprising the following steps: (1) Preparation of tetra-arm imine topological crosslinking agent: Weigh polyether triamine ZT-143 and terephthalaldehyde and add them to a three-necked flask. Add chloroform solvent. The ratio of the total weight of polyether triamine ZT-143 and terephthalaldehyde to chloroform is 2g:10-12mL. Stir magnetically to fully dissolve the raw materials and form a homogeneous reaction system A. Place the above reaction system A in a constant temperature water bath and stir at 45~55℃ for condensation reaction for 2~4h. After the reaction is completed, remove the chloroform solvent in the reaction system by vacuum distillation to obtain the tetra-arm imine topological crosslinking agent. (2) Preparation of polyurea prepolymer: Hexamethylene diisocyanate was weighed and dissolved in chloroform. The mass ratio of hexamethylene diisocyanate to chloroform was 3.36 g: 15-20 mL. The dissolved hexamethylene diisocyanate was added to a dry three-necked flask, and an inert gas was introduced as an inert protective atmosphere. Polyetheramine D-400 was added to 15 mL of chloroform to obtain a polyetheramine D-400 mixed solution. The mass ratio of polyetheramine D-400 to chloroform was 7.2 g: 15-20 mL. The polyetheramine D-400 mixed solution was slowly added dropwise to the three-necked flask, and the addition polymerization reaction was carried out by magnetic stirring at 23-27 °C for 1.8-2.2 h to obtain isocyanate-terminated polyurea prepolymer. (3) Crosslinking and curing: The tetra-armed imine topological crosslinking agent prepared in step (1) is dissolved in chloroform. The ratio of the tetra-armed imine topological crosslinking agent to chloroform is 1g: 5-10mL. Then it is added dropwise to the isocyanate-terminated polyurea prepolymer in step (2). After the addition is complete, the mixture is magnetically stirred for 3-5 minutes to mix evenly. Then it is ultrasonically dispersed for 3-5 minutes to obtain a homogeneous crosslinking reaction system B. The crosslinking reaction system B is poured into a polytetrafluoroethylene mold and placed at room temperature for 12-24 hours to evaporate the solvent. Then it is transferred to a vacuum oven at 75-85℃ for high-temperature curing for 22-26 hours. After curing, the mold is removed to obtain the polyurea material.

[0012] In the aforementioned step (1), the temperature of the condensation reaction is 50℃ and the reaction time is 3h; the pressure of the vacuum distillation is -0.070~-0.098MPa, the vacuum distillation temperature is 30~55℃, and the vacuum distillation time is 1~3h.

[0013] In step (2) above, the temperature of the addition polymerization reaction is 25°C, the reaction time is 2h, and the inert gas is nitrogen or argon.

[0014] In the aforementioned step (3), the ultrasonic time is 3 min, the room temperature placement time is 12 h, the high temperature curing temperature in the vacuum oven is 80 °C, and the high temperature curing time is 24 h.

[0015] The aforementioned application of tensile self-reinforced topological cross-linked recyclable polyurea materials in building waterproof protective coatings and impact-resistant engineering protective materials.

[0016] Compared with the prior art, the present invention has the following beneficial effects: This invention designs a four-arm topological crosslinking agent containing dynamic imine bonds and introduces it into a polyurea system to construct a dynamic topological crosslinking network, resulting in a polyurea material with an initial tensile strength of 31.29 MPa and a fracture toughness of 181.15 MJ / m. 3 After pre-stretching, the strength can be increased to 42.09 MPa, and the toughness can be increased to 202.26 MJ / m. 3 Compared to pure polyurea materials without the addition of a tetra-arm imine topological crosslinking agent, the tensile strength is increased by 83.6% and the fracture toughness is increased by 85.6%, while the elongation at break still maintains excellent ductility of over 1000%, solving the industry problem of the trade-off between strength and toughness in existing dynamic polyurea.

[0017] The polyurea material prepared by this invention can balance strength, toughness, and recyclability. After being hot-pressed for 30 minutes at 100℃ and 10MPa for three recycling cycles, the strength retention rate of the polyurea material is >84%. Furthermore, it possesses unique tensile self-reinforcing properties, overcoming the inherent defect of performance degradation after stress in traditional polymer materials, and can better meet the application requirements of high-end scenarios such as impact protection.

[0018] The preparation method of this invention is simple, with mild reaction conditions and widely available raw materials. It does not require complex production equipment or harsh reaction conditions, and can be scaled up and applied, providing a feasible technical path for the industrial production of high-performance recyclable polyurea materials. Attached Figure Description

[0019] Figure 1 The infrared spectrum of the four-armed imine topological crosslinker; Figure 2 The infrared spectrum of the polyurea material prepared in Example 6; Figure 3 Mechanical property test curves of polyurea materials modified with topological crosslinking agents of different molar ratios; Figure 4 A comparison of the tensile strength of topologically cross-linked polyurea material in its initial state and after 5 days of room temperature storage following pre-stretching treatment. Figure 5 This is a comparison chart of the mechanical properties of topologically cross-linked polyurea materials after multiple recycling. Detailed Implementation

[0020] The present invention will be further described below with reference to embodiments, but these embodiments are not intended to limit the scope of the invention.

[0021] This invention discloses a tensile self-reinforced topologically crosslinked recyclable polyurea material and its preparation method. The polyurea material is formed by addition polymerization of a four-armed imine topological crosslinking agent and a terminal isocyanate-based polyurea prepolymer. By utilizing the synergistic effect of the dynamic imine bonds in the crosslinking agent and the hydrogen bonds in the polyurea system, a stable dynamic topological crosslinking network is constructed, thereby achieving a synergistic improvement in the material's strength, toughness, and recyclability. At the same time, the material possesses unique tensile self-reinforcing properties.

[0022] The preparation method of the stretch self-reinforced topological crosslinking recyclable polyurea material of the present invention includes three core steps: preparation of a tetra-armed imine topological crosslinking agent, preparation of polyurea prepolymer, and crosslinking curing molding. The process parameters of each step are key to achieving the material properties. The technical solution of the present invention will be described in detail below through different embodiments, wherein the amount of tetra-armed imine topological crosslinking agent added is a different proportion of the total molar amount of amino components.

[0023] Unless otherwise specified, all reagents used in the following examples were purchased commercially (polyethertriamine ZT-143 was purchased from Anhui Zesheng Technology Co., Ltd., terephthalaldehyde was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., hexamethylene diisocyanate was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., and polyetheramine D-400 was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.).

[0024] Example 1: Preparation of a four-armed imine topological crosslinking agent Weigh 1.76 g of polyether triamine ZT-143 and 0.268 g of terephthalaldehyde in a molar ratio of 2:1, add them to a three-necked flask, and then add 10 mL of chloroform as an organic solvent. Stir magnetically to fully dissolve the raw materials and form a homogeneous reaction system A. Place the above reaction system A in a constant temperature water bath at 50°C and stir at a constant temperature to carry out a condensation reaction for 3 hours. After the reaction is completed, remove the chloroform solvent from the system by vacuum distillation. The pressure of vacuum distillation is -0.08 MPa, the temperature of vacuum distillation is 40°C, and the time of vacuum distillation is 2 hours, to obtain a light yellow viscous four-armed imine topological crosslinking agent.

[0025] The molecular chain of this four-armed imine topological crosslinker contains dynamically reversible imine bonds and has active amino groups at its ends that can participate in polyurea addition polymerization. Its infrared spectrum is as follows: Figure 1 As shown, 1642cm -1 The presence of a characteristic stretching vibration peak of an imine bond (C=N) at 1589 cm⁻¹ confirms successful imine bond formation. -1 The retention of the primary amino characteristic peak confirms the presence of the active amino site.

[0026] Example 2 Preparation of a four-arm imine topological crosslinking agent Weigh 1.804 g of polyether triamine ZT-143 and 0.268 g of terephthalaldehyde at a molar ratio of 2.05:1, add them to a three-necked flask, and then add 11 mL of chloroform as an organic solvent. Stir magnetically to fully dissolve the raw materials and form a homogeneous reaction system A. Place the above reaction system A in a constant temperature water bath at 45°C and stir at a constant temperature to carry out the condensation reaction for 4 hours. After the reaction is completed, remove the chloroform solvent from the system by vacuum distillation. The pressure of vacuum distillation is -0.070 MPa, the temperature of vacuum distillation is 30°C, and the time of vacuum distillation is 1 hour, to obtain a light yellow viscous four-arm imine topological crosslinking agent.

[0027] Example 3 Preparation of a four-arm imine topological crosslinking agent Weigh 1.848 g of polyether triamine ZT-143 and 0.268 g of terephthalaldehyde at a molar ratio of 2.1:1, add them to a three-necked flask, and then add 12 mL of chloroform as an organic solvent. Stir magnetically to fully dissolve the raw materials and form a homogeneous reaction system A. Place the above reaction system A in a constant temperature water bath at 55°C and stir at a constant temperature to carry out the condensation reaction for 2 hours. After the reaction is completed, remove the chloroform solvent from the system by vacuum distillation. The pressure of vacuum distillation is -0.098 MPa, the temperature of vacuum distillation is 55°C, and the time of vacuum distillation is 3 hours, to obtain a light yellow viscous four-arm imine topological crosslinking agent.

[0028] Example 4 Preparation of polyurea materials This embodiment prepares a tensile self-reinforced topologically crosslinked recyclable polyurea material with a four-arm imine topological crosslinking agent addition amount of 10% of the total molar amount of amino components (polyether triamine ZT-143 and polyether amine D-400 components).

[0029] (1) Preparation of polyurea prepolymer Weigh 3.36 g of hexamethylene diisocyanate (HDI) at a molar ratio of 1:0.9 and dissolve it in 15 ml of chloroform. Add the solution to a dry three-necked flask and mix thoroughly. Purge with nitrogen as an inert protective atmosphere. Separately, weigh 7.2 g of polyetheramine D-400 and add it to 15 ml of chloroform to obtain a polyetheramine D-400 mixed solution. Slowly add the solution dropwise to the three-necked flask and carry out an addition polymerization reaction at 25 °C with magnetic stirring for 2 h to obtain isocyanate-terminated polyurea prepolymer.

[0030] (2) Cross-linking and curing of polyurea materials 0.978 g of the tetra-arm imine topological crosslinking agent prepared in Example 1 was dissolved in 5 ml of chloroform and added to 10.56 g of the isocyanate-terminated polyurea prepolymer prepared in Example 2. After the addition was completed, the mixture was magnetically stirred for 3 min, and after being mixed evenly, it was ultrasonically dispersed for 3 min to obtain a homogeneous crosslinking reaction system B. The crosslinking reaction system B was poured into a polytetrafluoroethylene mold and left at room temperature for 12 h to evaporate the solvent. Then it was transferred to a vacuum oven at 80 °C for high-temperature curing for 24 h. After curing, it was demolded to obtain the tensile self-reinforced topological crosslinked recyclable polyurea material.

[0031] Example 5: Preparation of Polyurea Materials This embodiment prepares a tensile self-reinforced topologically crosslinked recyclable polyurea material with a tetra-arm imine topological crosslinking agent addition amount of 15% of the total molar amount of amino components (polyether triamine ZT-143 and polyether amine D-400 components).

[0032] (1) Preparation of polyurea prepolymer 3.36 g of hexamethylene diisocyanate (HDI) was weighed at a molar ratio of 1:0.85 and dissolved in 18 ml of chloroform. The solution was then added to a dry three-necked flask and mixed thoroughly. Nitrogen gas was introduced as an inert protective atmosphere. Next, 6.8 g of polyetheramine D-400 was weighed and added to 18 ml of chloroform to obtain a polyetheramine D-400 mixed solution. This solution was slowly added dropwise to the three-necked flask, and the mixture was magnetically stirred at 25°C for 2 hours to carry out an addition polymerization reaction, yielding an isocyanate-terminated polyurea prepolymer.

[0033] (2) Cross-linking and curing of polyurea materials 1.48 g of the tetra-arm imine topological crosslinking agent prepared in Example 1 was weighed and dissolved in 8 ml of chloroform. It was then added dropwise to 10.16 g of the isocyanate-terminated polyurea prepolymer prepared in Example 4. After the addition was complete, the mixture was magnetically stirred for 4 min. After mixing evenly, it was sonicated for 5 min to obtain a homogeneous crosslinking reaction system B. The crosslinking reaction system B was poured into a polytetrafluoroethylene mold and left at room temperature for 18 h to evaporate the solvent. After curing in a vacuum oven at 80 °C for 24 h, the mold was removed to obtain the polyurea material.

[0034] Example 6: Preparation of Polyurea Materials This embodiment prepares a tensile self-reinforced topologically crosslinked recyclable polyurea material with a four-arm imine topological crosslinking agent addition amount of 20% of the total molar amount of amino components (polyether triamine ZT-143 and polyether amine D-400 components).

[0035] (1) Preparation of polyurea prepolymer Weigh 3.36 g of hexamethylene diisocyanate (HDI) at a molar ratio of 1:0.8 and dissolve it in 20 ml of chloroform. Add the solution to a dry three-necked flask and mix thoroughly. Purge with nitrogen as an inert protective atmosphere. Separately weigh 6.4 g of polyetheramine D-400 and mix it in 20 ml of chloroform to obtain a polyetheramine D-400 mixed solution. Slowly add the solution dropwise to the three-necked flask and carry out an addition polymerization reaction at 25°C with magnetic stirring for 2 hours to obtain isocyanate-terminated polyurea prepolymer.

[0036] (2) Cross-linking and curing of polyurea materials 1.974 g of the tetra-arm imine topological crosslinking agent prepared in Example 1 was weighed and dissolved in 10 ml of chloroform. The solution was then added dropwise to 9.76 g of the isocyanate-terminated polyurea prepolymer prepared in Example 4. After the addition was complete, the mixture was magnetically stirred for 5 min. After mixing evenly, the mixture was sonicated for 5 min to obtain a homogeneous crosslinking reaction system B. The crosslinking reaction system B was poured into a polytetrafluoroethylene mold and left at room temperature for 18 h to evaporate the solvent. After curing in a vacuum oven at 80 °C for 24 h, the mixture was demolded to obtain the polyurea material.

[0037] The infrared spectrum of this polyurea material is as follows: Figure 2 As shown, 2270cm-1 The complete disappearance of the isocyanate group characteristic peak confirms that the polymerization reaction is complete (1623 cm⁻¹). -1 The presence of superimposed characteristic peaks of urea and imine bonds confirms the successful construction of the topological crosslinking network.

[0038] Example 7: Preparation of Polyurea Materials This embodiment prepares a tensile self-reinforced topologically crosslinked recyclable polyurea material with a four-arm imine topological crosslinking agent addition amount of 20% of the total molar amount of amino components (polyether triamine ZT-143 and polyether amine D-400 components).

[0039] (1) Preparation of polyurea prepolymer Weigh 3.36 g of hexamethylene diisocyanate (HDI) at a molar ratio of 1:0.8 and dissolve it in 20 ml of chloroform. Add the solution to a dry three-necked flask and mix thoroughly. Purge with nitrogen as an inert protective atmosphere. Separately weigh 6.4 g of polyetheramine D-400 and mix it in 20 ml of chloroform to obtain a polyetheramine D-400 mixed solution. Slowly add the solution dropwise to the three-necked flask and carry out an addition polymerization reaction at 27°C with magnetic stirring for 1.8 h to obtain isocyanate-terminated polyurea prepolymer.

[0040] (2) Cross-linking and curing of polyurea materials 1.974 g of the tetra-arm imine topological crosslinking agent prepared in Example 1 was weighed and dissolved in 10 ml of chloroform. This solution was then added dropwise to 9.76 g of the isocyanate-terminated polyurea prepolymer prepared in Example 4. After the addition was complete, the mixture was magnetically stirred for 3 min. After mixing evenly, the mixture was sonicated for 3 min to obtain a homogeneous crosslinking reaction system B. The crosslinking reaction system B was poured into a polytetrafluoroethylene mold and left at room temperature for 12 h to evaporate the solvent. Subsequently, it was transferred to a vacuum oven at 75 °C for high-temperature curing for 26 h. After curing, the mold was removed to obtain the polyurea material.

[0041] Example 8: Preparation of Polyurea Material This embodiment prepares a tensile self-reinforced topologically crosslinked recyclable polyurea material with a four-arm imine topological crosslinking agent addition amount of 20% of the total molar amount of amino components (polyether triamine ZT-143 and polyether amine D-400 components).

[0042] (1) Preparation of polyurea prepolymer Weigh 3.36 g of hexamethylene diisocyanate (HDI) at a molar ratio of 1:0.8 and dissolve it in 20 ml of chloroform. Add the solution to a dry three-necked flask and mix thoroughly. Purge with nitrogen as an inert protective atmosphere. Separately weigh 6.4 g of polyetheramine D-400 and mix it in 20 ml of chloroform. Slowly add the mixture dropwise to the three-necked flask and carry out an addition polymerization reaction at 23°C with magnetic stirring for 2.2 h to obtain isocyanate-terminated polyurea prepolymer.

[0043] (2) Cross-linking and curing of polyurea materials 1.974 g of the tetra-arm imine topological crosslinking agent prepared in Example 1 was dissolved in 10 ml of chloroform and added dropwise to 9.76 g of the isocyanate-terminated polyurea prepolymer prepared in Example 4. After the addition was completed, the mixture was magnetically stirred for 4 min, and after being mixed evenly, it was sonicated for 4 min to obtain a homogeneous crosslinking reaction system B. The crosslinking reaction system B was poured into a polytetrafluoroethylene mold and left at room temperature for 18 h to evaporate the solvent. Then it was transferred to a vacuum oven at 85 °C for high-temperature curing for 22 h. After curing, it was demolded to obtain the polyurea material.

[0044] Comparative Example 1 To compare the performance advantages of the modified polyurea material of this invention, a pure polyurea material without the addition of a four-arm imine topological crosslinking agent was prepared as a comparative example. The specific steps are as follows: 3.36 g of hexamethylene diisocyanate (HDI) was weighed at a molar ratio of 1:1 and dissolved in 20 ml of chloroform. This solution was then added to a dry three-necked flask and mixed thoroughly. Nitrogen gas was introduced as an inert protective atmosphere. Next, 8 g of polyetheramine D-400 was weighed and mixed in 20 ml of chloroform, and slowly added dropwise to the three-necked flask. The mixture was stirred at 25°C for 2 hours and sonicated for 5 minutes. The reaction mixture was then poured into a polytetrafluoroethylene mold, left at room temperature for 24 hours, cured at 80°C for 24 hours, and then demolded to obtain pure polyurea material.

[0045] Experimental Example 1: Mechanical Property Testing 1. The polyurea materials prepared in Examples 4, 5, and 6, and the pure polyurea material prepared in Comparative Example 1, were subjected to mechanical property testing. The testing methods conformed to the relevant standards for tensile property testing of polymer materials. The test results are as follows: Figure 3 As shown.

[0046] Combination Figure 3 As shown, the optimal tensile strength of the tensile self-reinforced topological crosslinked recyclable polyurea material prepared in Example 6 is 31.29 MPa, or 181.15 MJ / m. 3 Compared to pure polyurea materials without the addition of a tetra-arm imine topological crosslinking agent, the tensile strength is increased by 83.6%, the fracture toughness is increased by 85.6%, and the elongation at break still maintains excellent ductility of over 1000%.

[0047] 2. The polyurea material prepared in Example 6 was used as the initial sample. A sample of the polyurea material prepared in Example 6, stretched to 500% strain and left for 5 days, was used as a pre-stretched sample. The tensile properties of the initial sample and the pre-stretched sample were compared. Figure 4As shown, the tensile self-reinforced topological crosslinked recyclable polyurea material prepared in Example 6, after being pre-stretched to 500% strain and then pretreated at room temperature for 5 days, exhibits improved mechanical properties of 42.09 MPa and 202.26 MJ / m². 3 .

[0048] Experiment Example 2: Recycling Performance Test Combination Figure 5 As shown, the recyclability of the polyurea material prepared in the optimal example 6 was tested. It was hot-pressed at 100°C and 10MPa for 30 minutes and the operation was repeated 3 times. The strength retention rate of the recycled polyurea material was >84%.

Claims

1. A stretch-reinforced, topologically cross-linked, recyclable polyurea material, characterized in that: Polyurea materials are topologically cross-linked network structures formed by addition polymerization of tetra-arm imine topological cross-linking agents and isocyanate-terminated polyurea prepolymers. The four-armed imine topological crosslinking agent is a four-armed structure product prepared by condensation reaction of polyether triamine ZT-143 and terephthalaldehyde. The molecular chain contains dynamic reversible imine bonds, and the molecular ends have active amino groups that can participate in polyurea reactions. The molar ratio of polyether triamine ZT-143 to terephthalaldehyde is 2~2.1:

1. The isocyanate-terminated polyurea prepolymer is obtained by the addition polymerization reaction of hexamethylene diisocyanate and polyetheramine D-400, wherein the molar ratio of hexamethylene diisocyanate to polyetheramine D-400 is 1:0.80~0.

9.

2. The tensile self-reinforced topological crosslinking recyclable polyurea material according to claim 1, characterized in that: The molecular structural formula of the four-armed imine topological crosslinking agent is: 。 3. The tensile self-reinforced topological crosslinking recyclable polyurea material according to claim 1, characterized in that: The molar ratio of the tetra-armed imine topological crosslinking agent to the terminal isocyanate-based polyurea prepolymer is 0.05~0.1:

1.

4. The tensile self-reinforced topological crosslinking recyclable polyurea material according to claim 1, characterized in that: The molar ratio of polyether triamine ZT-143 to terephthalaldehyde is 2:

1.

5. The tensile self-reinforced topological crosslinking recyclable polyurea material according to claim 1, characterized in that: The molar ratio of hexamethylene diisocyanate to polyetheramine D-400 is 1:0.

80.

6. The method for preparing a tensile self-reinforced topologically cross-linked recyclable polyurea material according to any one of claims 1 to 5, characterized in that, Includes the following steps: (1) Preparation of tetra-arm imine topological crosslinking agent: Weigh polyether triamine ZT-143 and terephthalaldehyde and add them to a three-necked flask. Add chloroform solvent. The ratio of the total weight of polyether triamine ZT-143 and terephthalaldehyde to chloroform is 2g:10-12mL. Stir magnetically to fully dissolve the raw materials and form a homogeneous reaction system A. Place the above reaction system A in a constant temperature water bath and stir at 45~55℃ for condensation reaction for 2~4h. After the reaction is completed, remove the chloroform solvent in the reaction system by vacuum distillation to obtain the tetra-arm imine topological crosslinking agent. (2) Preparation of polyurea prepolymer: Hexamethylene diisocyanate was weighed and dissolved in chloroform. The mass ratio of hexamethylene diisocyanate to chloroform was 3.36 g: 15-20 mL. The dissolved hexamethylene diisocyanate was added to a dry three-necked flask, and an inert gas was introduced as an inert protective atmosphere. Polyetheramine D-400 was added to 15 mL of chloroform to obtain a polyetheramine D-400 mixed solution. The mass ratio of polyetheramine D-400 to chloroform was 7.2 g: 15-20 mL. The polyetheramine D-400 mixed solution was slowly added dropwise to the three-necked flask, and the addition polymerization reaction was carried out by magnetic stirring at 23-27 °C for 1.8-2.2 h to obtain isocyanate-terminated polyurea prepolymer. (3) Crosslinking and curing: The tetra-armed imine topological crosslinking agent prepared in step (1) is dissolved in chloroform. The ratio of the tetra-armed imine topological crosslinking agent to chloroform is 1g: 5-10mL. Then it is added dropwise to the isocyanate-terminated polyurea prepolymer in step (2). After the addition is complete, the mixture is magnetically stirred for 3-5 minutes to mix evenly. Then it is ultrasonically dispersed for 3-5 minutes to obtain a homogeneous crosslinking reaction system B. The crosslinking reaction system B is poured into a polytetrafluoroethylene mold and placed at room temperature for 12-24 hours to evaporate the solvent. Then it is transferred to a vacuum oven at 75-85℃ for high-temperature curing for 22-26 hours. After curing, the mold is removed to obtain the polyurea material.

7. The preparation method according to claim 6, characterized in that: In step (1), the temperature of the condensation reaction is 50℃ and the reaction time is 3h; the pressure of the vacuum distillation is -0.070~-0.098MPa, the vacuum distillation temperature is 30~55℃, and the vacuum distillation time is 1~3h.

8. The preparation method according to claim 6, characterized in that: In step (2), the temperature of the addition polymerization reaction is 25°C, the reaction time is 2 hours, and the inert gas is nitrogen or argon.

9. The preparation method according to claim 6, characterized in that, In step (3), the ultrasonic time is 3 min, the room temperature placement time is 12 h, the high temperature curing temperature in the vacuum oven is 80 °C, and the high temperature curing time is 24 h.

10. The application of the tensile self-reinforced topological crosslinking recyclable polyurea material according to any one of claims 1 to 9 in building waterproof protective coatings and impact-resistant engineering protective materials.

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