A heat-resistant self-repairing polyurethane elastic system and preparation method thereof

Abstract

The present invention discloses a heat-resistant, self-healing polyurethane elastomer system and its preparation method. 3,3'-diaminobenzidine (DAB) and 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BDTA) are reacted in a first solvent to obtain a DTA solution. A diisocyanate compound is then added to obtain a DTA-NCO solution. A second solvent, a polyol compound, and a catalyst are then added to perform a prepolymerization reaction followed by heat treatment to obtain a heat-resistant, high-strength, self-healing polyurethane system. Compared to existing similar self-healing polyurethane elastomer systems, the product of the present invention exhibits superior mechanical properties, outstanding heat resistance, and high self-healing behavior, significantly improving the high-temperature usability and safety of the self-healing polyurethane elastomer system, facilitating its application in advanced materials such as aerospace.

Description

Technical Field

[0001] The present invention belongs to the field of polyurethane systems, and in particular relates to a heat-resistant self-repairing polyurethane elastomer system and a preparation method thereof. Background Art

[0002] Polyurethane elastomer materials are widely used in the automotive, aerospace, flexible electronics and medical fields due to their excellent ductility, chemical resistance and wear resistance. However, a large amount of discarded polyurethane materials often cause serious environmental pollution and waste of resources. The development of polyurethane materials with self-healing functions can effectively solve the above problems. In recent years, self-healing polyurethane elastomer systems based on non-covalent bonds have shown great application potential in coatings, foams, automobiles, biomedicine and electronic equipment. Although self-healing polyurethane elastomer systems based on non-covalent bonds can exhibit excellent mechanical properties and high self-healing efficiency under mild conditions, with the complexity and variability of the material application environment, this type of self-healing polyurethane system can no longer meet the performance development requirements due to its poor heat resistance and generally low mechanical properties.

[0003] CN119798743A provides a self-repairing polyurethane film containing disulfide bonds and DA bonds and a preparation method thereof, comprising the following steps: (1) adding an organic solvent into a three-necked flask, then dissolving a diol, a diisocyanate, a disulfide bond monomer, and a DA bond-forming monomer in the organic solvent, then adding a catalyst, and mechanically stirring the mixture until uniform; (2) introducing nitrogen into the three-necked flask to evacuate the air, setting the reaction temperature, and reacting under mechanical stirring; (3) under a nitrogen environment, adding the DA bond-forming monomer two drops to the solution obtained after the reaction in step (2); after the addition of the DA bond-forming monomer two drops is completed, setting the reaction temperature, and reacting for a period of time; (4) pouring the solution obtained after the reaction in step (3) into a polytetrafluoroethylene mold, drying the mixture, and obtaining a self-repairing polyurethane film having a tensile strength of 31 MPa and a repair rate of 83%. CN119798599A discloses a self-healing waterborne polyurethane and its preparation method and application, comprising the following raw materials: polyisocyanate, macromolecular polyol, small molecule chain extender, carboxylic acid type hydrophilic compound, amino compound, neutralizer, water, catalyst; the provided waterborne polyurethane is subjected to 40°C for 8 hours, and the repair rate is about 95%. CN119751935A discloses a preparation method and application of a degradable, fluorescent self-healing polyurethane film, comprising: dissolving o-phenylenediamine and tryptophan in a solvent, adding an acid solution and deionized water to dissolve to obtain a mixed solution, transferring the mixed solution to a Teflon-lined autoclave for reaction to obtain carbon quantum dots; (2) using isocyanate, polyol and dispersing solvent as raw materials, adding an organic tin catalyst, and then adding a chain extender to react to obtain a polyurethane solution; (3) adding carbon quantum dots to the polyurethane solution, stirring, casting the solution onto a polytetrafluoroethylene substrate for self-leveling, and drying to obtain a degradable, fluorescent self-healing polyurethane film, but its self-healing efficiency is relatively low. CN119431720A discloses a polyurethane with multi-dynamic bond synergistic self-repairing properties and a preparation method thereof. The raw materials include polyglycol, diisocyanate, pyridine chain extender, catechol and trivalent iron ion salt. The self-repair efficiency of the product is about 90%.

[0004] Therefore, the development of a high-strength, heat-resistant, and highly applicable self-healing polyurethane elastomer system has greater social value and economic benefits. Summary of the Invention

[0005] The present invention addresses the problems of poor heat resistance and low mechanical properties in existing non-covalent bond self-healing polyurethane elastic systems. By using 3,3'-diaminobenzidine (DAB) and 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BDTA) as raw materials, combined with diisocyanate compounds and polyol compounds, and through the use of solvents, the system's heat resistance and self-healing properties are improved. In particular, the system exhibits excellent mechanical strength and self-healing properties (~100%), which are beyond the expectations of those skilled in the art.

[0006] In order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is as follows.

[0007] A heat-resistant self-repairing polyurethane elastic system and a preparation method thereof, comprising the following steps: using DAB and BDTA as raw materials, reacting in a first solvent to obtain a DTA solution; then adding a diisocyanate compound, reacting to obtain a DTA-NCO solution; then adding a second solvent, a polyol compound, and a catalyst, performing a prepolymerization reaction and then a heat treatment to obtain the heat-resistant self-repairing polyurethane elastic system; the molar ratio of DAB, BDTA, diisocyanate compound, polyol compound, catalyst, first solvent, and second solvent is 2: (0.8-1.2): (15-20): (1.25-3.25): (0.01-0.05): (100-160): (100-150).

[0008] In the present invention, when reacting in the first solvent, the reaction temperature is 80-100°C and the reaction time is 0.5-2 hours (h) to obtain an oligomer (DTA) solution, and the reaction temperature is 90-110°C and the reaction time is 0.5-2 hours to obtain a DTA-NCO solution. In the second solvent, during the prepolymerization reaction, the reaction temperature is 70-90°C and the reaction time is 0.5-2 hours. The heat treatment process is 40-60°C / 10-15 hours + 80-100°C / 4-6 hours.

[0009] Preferably, the molar ratio of DAB, BDTA, diisocyanate compound, polyol compound, catalyst, first solvent, and second solvent is 2:1:16: (1.25-3.25): (0.01-0.05): (100-160): (100-150). The heat-resistant, self-healing polyurethane elastic system of the present invention has a low-temperature glass transition temperature of less than -35°C and a high-temperature glass transition temperature of greater than 205°C. Preferably, the material prepared by the present invention exhibits both ultra-low-temperature (-52°C) and ultra-high-temperature glass transition temperatures (226°C), a high thermal decomposition temperature, and excellent mechanical strength and self-healing properties (~100%).

[0010] In the present invention, the first solvent and the second solvent are independently selected from one or more of N,N-dimethylformamide, acetone, and ethanol; and the catalyst includes one or more of organic tin and organic lead.

[0011] The invention discloses a polyurethane elastomer material, the raw materials for preparing the polyurethane elastomer material include the above-mentioned heat-resistant self-repairing polyurethane elastic system.

[0012] The invention discloses application of the heat-resistant self-repairing polyurethane elastic system in the preparation of polyurethane materials.

[0013] The present invention discloses the application of the heat-resistant self-repairing polyurethane elastic system in the preparation of self-repairing materials.

[0014] The present invention discloses the application of the heat-resistant self-repairing polyurethane elastic system in the preparation of aerospace materials.

[0015] Compared with the prior art, the present invention has the following beneficial effects: the polyurethane elastomer of the present invention has both high strength and high self-repairing performance, and has the advantages of ultra-low temperature T g (-52°C), also has ultra-high temperature T g (~226°C) and a high initial thermal decomposition temperature (~314°C), it has the performance to be used in both low and ultra-high temperature environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 FTIR spectra of DTA-NCO, PTMEG, HDI and the sample of Example 1.

[0017] Figure 2 This is the UV-vis absorption diagram of the sample in Example 1.

[0018] Figure 3 These are photos of the scratched sample of Example 1 before and after heat treatment at 180°C for 2h and the scratched sample of Comparative Example 1-1 before and after heat treatment at 180°C and 140°C for 2h, respectively, where (a) is a photo of the sample of Example 1, and (b) and (c) are photos of the sample of Comparative Example 1.

[0019] Figure 4 Photos of the scratched sample of the control example before and after heat treatment at 180°C for 2h.

[0020] Figure 5 These are photos of the scratched sample in Example 2 before and after heat treatment at 160°C for 2h.

[0021] Figure 6 These are photos of the scratched sample in Example 3 before and after heat treatment at 140°C for 2h.

[0022] Figure 7 These are photos of the scratched sample in Example 4 before and after heat treatment at 160°C for 2h.

[0023] Figure 8 These are photos of the scratched sample in Example 5 before and after heat treatment at 160°C for 2h. DETAILED DESCRIPTION

[0024] The present invention dissolves DAB and BDTA in a first solvent, then drops the BDTA solution into the DAB solution and reacts at 90°C for 0.5-2 hours to obtain a DTA solution. A diisocyanate compound is then dropped into the DTA solution and reacted at 100°C for 0.5-1 hour to obtain a DTA-NCO solution. A second solvent, a polyol compound, and a catalyst are then added, reacting at 80°C under nitrogen for 0.5-2 hours. The solution is then cast into a mold and heat-treated at 50°C for 12 hours followed by 80-100°C for 4-6 hours to obtain a heat-resistant self-healing polyurethane elastic film. The molar ratios of DAB:BDTA:diisocyanate compound:polyol compound:catalyst:first solvent:second solvent are 2:1:16:(1.25-3.25):(0.01-0.05):(100-160):(100-150).

[0025] In the present invention, the polyol includes one or more of polyether polyol and polyester polyol; the diisocyanate compound includes one or more of isophorone diisocyanate (IPDI), toluene diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate, hexamethylene diisocyanate (HDI), and lysine diisocyanate; the solvent is one or a mixture of N,N-dimethylformamide (DMF), acetone, and ethanol; and the catalyst is one or more of organic tin (such as dibutyltin dilaurate, stannous octoate, etc.) and organic lead (such as tetraethyl lead and triethyl lead).

[0026] In the present invention, the heat-resistant self-healing polyurethane elastic system has obvious ultra-low temperature (-52°C) and ultra-high temperature glass transition temperature (226°C), a high thermal decomposition temperature, and exhibits excellent mechanical strength and self-healing performance (~100%).

[0027] The following is an illustration of the technological advancement of the present invention through specific experiments. The raw materials used are all existing products, and the specific preparation operations and performance tests are all conventional techniques. Unless otherwise specified, molecular weight refers to the number-average molecular weight.

[0028] Example 1

[0029] 3,3'-diaminobenzidine DAB (2mmol) and 3,3',4,4'-benzophenonetetracarboxylic dianhydride BDTA (1mmol) were dissolved in DMF (first solvent, 60mmol each) solvent, and then the BDTA solution was added dropwise to the DAB solution and reacted at 90℃ for 1.5h to obtain a DTA solution; then hexamethylene diisocyanate HDI (16mmol) was added dropwise to the DTA solution and reacted at 100℃ for 0.5h to obtain a DTA-NCO solution; then DMF (second solvent, 130mmol), polytetrahydrofuran PTMEG-2000 (1.25mmol) with a molecular weight of 2000 and dibutyltin dilaurate DBTDL (0.04mmol) were added at room temperature, and the mixture was reacted at 80℃ for 2h under nitrogen protection. The solution was then cast into a mold (conventional method) and heated at 50℃ / 12h+ A polyurethane elastomer (PUE-DTA) film was obtained by heat treatment at 80°C for 6 hours, wherein the molar ratio of DAB:BDTA:diisocyanate compound:polyol compound:first solvent:second solvent was 2:1:16:1.25:120:130.

[0030] Comparative Example 1-1

[0031] HDI (16 mmol), DMF (130 mmol), polytetrahydrofuran (PTMEG-2000) (1.25 mmol) and DBTDL (0.04 mmol) were mixed and reacted at 80 °C for 2 h under nitrogen protection. The solution was then cast into a mold and heat treated at 50 °C for 12 h + 80 °C for 6 h to obtain a polyurethane film.

[0032] Comparative Example 1-2

[0033] DAB (2 mmol) was dissolved in DMF (first solvent, 60 mmol), followed by the addition of hexamethylene diisocyanate (HDI) (16 mmol) and the reaction at 100°C for 0.5 h. DMF (second solvent, 130 mmol), polytetrahydrofuran (PTMEG-2000) (1.25 mmol) with a molecular weight of 2000, and dibutyltin dilaurate (DBTDL) (0.04 mmol) were then added at room temperature, followed by the reaction at 80°C for 2 h under nitrogen protection. The solution was then cast into a mold (conventional method) and heat-treated at 50°C for 12 h + 80°C for 6 h to obtain a polymer film. The molar ratio of DAB: diisocyanate compound: polyol compound: first solvent: second solvent was 2:16:1.25:60:130.

[0034] Comparative Examples 1-3

[0035] BDTA (1 mmol) was dissolved in DMF (first solvent, 60 mmol), followed by the addition of hexamethylene diisocyanate (HDI) (16 mmol) and the reaction at 100°C for 0.5 h. DMF (second solvent, 130 mmol), polytetrahydrofuran (PTMEG-2000) with a molecular weight of 2000 (1.25 mmol), and dibutyltin dilaurate (DBTDL) (0.04 mmol) were then added at room temperature, followed by the reaction at 80°C for 2 h under nitrogen protection. The solution was then cast into a mold (conventional method) and heat-treated at 50°C for 12 h + 80°C for 6 h to obtain a polyurethane elastomer film. The molar ratio of BDTA: diisocyanate compound: polyol compound: first solvent: second solvent was 1:16:1.25:60:130.

[0036] DTA infrared (FTIR) spectrum data: 3100-3700 cm -1 : NH stretching vibration in -NH2; 1500 cm -1 : C=C stretching vibration in benzene ring; 1650cm -1 and 1720cm -1 : C=O stretching vibration in imide (-CONCO-); 1384cm -1 : CN stretching vibration.

[0037] Figure 1 FTIR spectra of DTA-NCO, PTMEG, HDI and the sample of Example 1; Figure 2 This is the UV-vis absorption diagram of the sample in Example 1. When DTA reacts with HDI, the product DTA-NCO does not show obvious -NH2 characteristic peak, but at 3326 cm -1 A weak -NH characteristic absorption peak appeared at 2260 cm -1 The characteristic peak of -NCO is at 1620cm -1 The absorption peak of C=O in urea group (-NHCONH-) appears at 2260 cm-1. The above phenomenon indicates that -NH2 in DTA reacts with -NCO in HDI and -NCO functionalizes DTA successfully. When DTA-NCO reacts with PTMEG, the product PUE-DTA -1 There is no characteristic absorption peak of -NCO at 3459cm -1 There is no -OH characteristic peak at 1780~1600cm -1 The C=O stretching vibration peak at the position of -NCO is enhanced, indicating that -NCO reacts with -OH to form -NHCOO- groups. The UV-vis absorption spectrum of the sample in Example 1 shows that its maximum absorption wavelength is 523 nm, indicating that the sample in Example 1 has a π→π* electronic transition, which is mainly due to the presence of a benzene ring structure in the sample.

[0038] Table 1 shows the mechanical properties, thermal performance parameters and scratch self-repair efficiency of the samples of Example 1 and Comparative Example after heat treatment at 180°C for 2h. Figure 3 Photos of a scratched sample from Example 1 before and after heat treatment at 180°C for 2 hours, and a scratched sample from Comparative Example 1-1 after heat treatment at 180°C and 140°C for 2 hours. The Example 1 sample had a tensile strength of 34 MPa and an elongation at break of 213%. Compared to the Comparative Example, the Example 1 sample had significantly higher tensile strength, exceeding that of the Comparative Example 1-1 sample by 183%. The Example 1 system had three glass transition temperatures (T g ), respectively -54 ° C, 149 ° C and 226 ° C. The sample of Example 1 not only has a low temperature T g , which is obviously two more high temperature T than the comparative example 1-1 g , which means that the system of the present invention has both low temperature and high temperature usability. In particular, Comparative Example 1-1 has only one low temperature T g , resulting in poor self-repairing ability and difficulty in high-temperature industrial applications. Example 1 Thermal decomposition temperature (T d5 ) and the maximum thermal decomposition rate temperature (T dmax ) were 308°C and 414°C, respectively, which were 33°C and 40°C higher than those of Comparative Example 1-1. The scratches on the surface of the sample in Example 1 were completely healed after heat treatment at 180°C for 2h ( Figure 3 In (a), the self-repair efficiency is 100%. After the sample of Comparative Example 1-1 was heat-treated at 180°C for 2h, the sample melted ( Figure 3 (b)), even if the sample is heat treated at 140 ° C for 2 h ( Figure 3 In (c), the surface scratches still did not heal well. This shows that the complete healing of the sample in Example 1 overcomes the prior art's technical prejudice that heat-resistant polyurethane self-healing materials are difficult to achieve complete healing.

[0039] Table 1 Mechanical properties, thermal performance parameters and scratch self-repair efficiency of samples in Example 1 and Comparative Example

[0040]

[0041] Control Example

[0042] 3,3'-Diaminobenzidine DAB (2 mmol) and 3,3',4,4'-benzophenonetetracarboxylic dianhydride BDTA (1 mmol) were dissolved in DMF (60 mmol) solvent respectively. Then, the 3,3',4,4'-benzophenonetetracarboxylic dianhydride solution was added dropwise to the 3,3'-diaminobenzidine solution and reacted at 90°C for 1.5 h to obtain an oligomer (DTA) solution. DMF (130 mmol) and HDI (59 mmol) were then added dropwise and reacted at 100°C for 1.5 h to obtain a -NCO functionalized DTA solution. DMF (260 mmol), polytetrahydrofuran (PTMEG-2000) (8 mmol) and DBTDL (0.04 mmol) were then added at room temperature and reacted at 80°C for 2 h under nitrogen protection to obtain a prepolymer solution. The solution was conventionally cast into a mold and heat-treated at 50°C for 12 h and 80°C for 6 h to obtain a polyurethane elastomer film. Figure 4 Photos of a scratched control sample before and after heat treatment at 180°C for 2 hours. After heat treatment at 180°C for 2 hours, the scratch on the control sample narrowed but remained visible. The self-healing efficiency was 48%, indicating incomplete repair. The molar ratio of 3,3'-diaminobenzidine: 3,3',4,4'-benzophenonetetracarboxylic dianhydride: diisocyanate compound: polyol compound: catalyst was 2:1:59:8:0.04.

[0043] Example 2

[0044] Referring to Example 1, the difference is that 2.25 mmol of polytetrahydrofuran (PTMEG-2000) with a molecular weight of 2000 is used. The rest is the same to obtain a film, that is, the molar ratio of DAB:BDTA:diisocyanate compound:polyol compound:first solvent:second solvent is 2:1:16:2.25:120:130.

[0045] Comparative Example 2

[0046] Referring to Comparative Example 1-1, the difference is that 2.25 mmol of polytetrahydrofuran (PTMEG) with a molecular weight of 2000 is used, and the rest is the same to obtain a film.

[0047] Table 2 shows the mechanical properties, thermal performance parameters and scratch self-repair efficiency of the samples of Example 2 and Comparative Example 2 after heat treatment at 160°C for 2h. Figure 5 The following are photos of the scratched sample from Example 2 before and after heat treatment at 160°C for 2 hours. The tensile strength of the system from Example 2 is 31 MPa, and the elongation at break is 276%. Compared to Comparative Example 2, Example 2 has a higher tensile strength, which is 78% higher. The system from Example 2 has three glass transition temperatures (T g ), respectively -54 ° C, 168 ° C and 226 ° C. The system of Example 2 not only has a low temperature Tg , which is obviously two more high temperature T than Comparative Example 2 g , which means that the system of the present invention has both low-temperature and high-temperature usability. The thermal decomposition temperature (T d5 ) and the maximum thermal decomposition rate temperature (T dmax ) were 313°C and 411°C, respectively, which were 37°C and 35°C higher than those in Comparative Example 2. The scratches on the surface of the sample in Example 2 were completely healed after heat treatment at 160°C for 2h, and its self-repair efficiency was 100%.

[0048] Table 2 Mechanical properties, thermal performance parameters and scratch self-repair efficiency of samples in Example 2 and Comparative Example 2

[0049]

[0050] Example 3

[0051] Referring to Example 1, except that 3.25 mmol of polytetrahydrofuran (PTMEG-2000) with a molecular weight of 2000 was used, and the rest was the same, a film was obtained, i.e., the molar ratio of DAB:BDTA:diisocyanate compound:polyol compound:first solvent:second solvent was 2:1:16:3.25:120:130, and the calculated hydrogen bond content was 41%.

[0052] Comparative Example 3

[0053] Referring to Comparative Example 1-1, the difference is that 3.25 mmol of polytetrahydrofuran (PTMEG-2000) with a molecular weight of 2000 is used, and the rest is the same to obtain a film.

[0054] Table 3 shows the mechanical properties, thermal performance parameters and scratch self-repair efficiency of the samples of Example 3 and Comparative Example 3 after heat treatment at 140°C for 2h. Figure 6 Photos of the scratched sample from Example 3 before and after heat treatment at 140°C for 2 hours. The tensile strength of the system from Example 3 was 34 MPa, and the elongation at break was 307%. Compared to Comparative Example 3, Example 3 had a higher tensile strength, 35% higher. The system from Example 3 had three glass transition temperatures (T g ), respectively -54 ° C, 149 ° C and 224 ° C. The system of Example 3 not only has a low temperature T g , which is obviously two more high temperature T than Comparative Example 3 g , which means that the system of the present invention has both low-temperature and high-temperature usability. d5 ) and the maximum thermal decomposition rate temperature (T dmax) were 314°C and 408°C, respectively, which were 41°C and 31°C higher than those in Comparative Example 3. The scratches on the surface of the sample in Example 3 were completely healed after heat treatment at 140°C for 2 h, and its self-repair efficiency was 100%.

[0055] Table 3 Mechanical properties, thermal performance parameters and scratch self-repair efficiency of samples in Example 3 and Comparative Example 3

[0056]

[0057] Example 4

[0058] DAB (2 mmol) and BDTA (1 mmol) were dissolved in DMF (50 mmol each). The BDTA solution was then added dropwise to the DAB solution and reacted at 90°C for 0.5 h to obtain a DTA solution. IPDI (16 mmol) was then added dropwise to the DTA solution and reacted at 100°C for 0.5 h to obtain a DTA-NCO solution. DMF (100 mmol), polyether polyol JX230 (2.25 mmol) with a number-average molecular weight of 2800, and DBTDL (0.01 mmol) were then added at room temperature. The mixture reacted at 80°C for 0.5 h under nitrogen. The solution was then cast into a mold and heat-treated at 50°C for 12 h followed by 100°C for 4 h to obtain a polyurethane film with a calculated hydrogen bond content of 52%. The molar ratios of DAB:BDTA:diisocyanate:polyol:catalyst:first solvent:second solvent were 2:1:16:2.25:0.01:100:100.

[0059] Comparative Example 4

[0060] IPDI (16 mmol), DMF (100 mmol), polyether polyol JX230 (2.25 mmol) with a number average molecular weight of 2800, and DBTDL (0.01 mmol) were heated to 80°C under nitrogen protection for 2 h. The solution was then cast into a mold and heat-treated at 50°C for 12 h and 80°C for 6 h to obtain a polyurethane system film.

[0061] Table 4 shows the mechanical properties, thermal performance parameters and scratch self-repair efficiency of the samples of Example 4 and Comparative Example 4 after heat treatment at 160°C for 2h. Figure 7 Photos of the scratched sample from Example 4 before and after heat treatment at 160°C for 2 hours. The tensile strength of the system from Example 4 was 18 MPa, and the elongation at break was 356%. Compared to Comparative Example 4, Example 4 had a higher tensile strength, 157% higher. The system from Example 4 had three glass transition temperatures (T g ), respectively -42 ° C, 175 ° C and 210 ° C. The system of Example 4 not only has a low temperature T g, which is obviously two more high temperature T than Comparative Example 4 g , which means that the system of the present invention has both low-temperature and high-temperature usability. d5 ) and the maximum thermal decomposition rate temperature (T dmax ) were 279°C and 356°C, respectively, which were 47°C and 64°C higher than those of Comparative Example 4. The self-repair efficiency of the scratches on the surface of the sample in Example 4 was 100% after heat treatment at 160°C for 2h.

[0062] Table 4 Mechanical properties, thermal performance parameters and scratch self-repair efficiency of samples in Example 4 and Comparative Example 4

[0063]

[0064] Example 5

[0065] DAB (2 mmol) and BDTA (1 mmol) were dissolved in DMF (80 mmol each), and the BDTA solution was added dropwise to the DAB solution and reacted at 90°C for 2 h to obtain a DTA solution. IPDI (12 mmol) and diphenylmethane diisocyanate (4 mmol) were then added dropwise to the DTA solution and reacted at 100°C for 1 h to obtain a DTA-NCO solution. DMF (100 mmol), acetone (50 mmol), a polyether polyol with a number average molecular weight of 2800 (2.5 mmol), and DBTDL (0.05 mmol) were then added at room temperature. The mixture was reacted at 80°C for 2 h under nitrogen protection. The solution was then cast into a mold and heat-treated at 50°C for 12 h + 100°C for 6 h to obtain a polyurethane film. The molar ratio of DAB:BDTA:diisocyanate compound:polyol compound:catalyst:first solvent:second solvent was 2:1:16:2.5:0.05:160:150.

[0066] Comparative Example 5

[0067] IPDI (12 mmol), diphenylmethane diisocyanate (4 mmol), DMF (100 mmol), acetone (50 mmol), polyether polyol with a number average molecular weight of 2800 (2.5 mmol), and DBTDL (0.05 mmol) were heated to 80°C under nitrogen protection for reaction for 2 h. The solution was then cast into a mold and heat treated at 50°C / 12 h + 100°C / 6 h to obtain a polyurethane system film.

[0068] Table 5 shows the mechanical properties, thermal performance parameters and scratch self-repair efficiency of the samples of Example 5 and Comparative Example 5 after heat treatment at 160°C for 2h. Figure 8Photos of the scratched sample from Example 5 before and after heat treatment at 160°C for 2 hours. The tensile strength of the system from Example 5 was 21 MPa, and the elongation at break was 332%. Compared to Comparative Example 5, Example 5 had a higher tensile strength, 110% higher. The system from Example 5 had three glass transition temperatures (T g ), respectively -37 ° C, 179 ° C and 220 ° C. Example 5 system not only has a low temperature T g , which is obviously two more high temperature T than Comparative Example 5 g , which means that the system of the present invention has both low-temperature and high-temperature usability. The thermal decomposition temperature (T d5 ) and the maximum thermal decomposition rate temperature (T dmax ) were 285°C and 361°C, respectively, which were 49°C and 59°C higher than those of Comparative Example 5. The self-repair efficiency of the scratches on the surface of the sample in Example 5 was 100% after heat treatment at 160°C for 2h.

[0069] Table 5 Mechanical properties, thermal performance parameters and scratch self-repair efficiency of samples in Example 5 and Comparative Example 5

[0070]

[0071] In the present invention, the sample performance test:

[0072] 5wt% weight loss temperature (T d5 ) and the maximum thermal weight loss rate thermal decomposition temperature (T dmax ) was measured using a thermogravimetric analyzer (Discovery, TGA550, TA Company, USA) in a nitrogen atmosphere at a heating rate of 10°C / min.

[0073] Glass transition temperature T g The dynamic mechanical analyzer (DMA, Q850, TA Company, USA) was used for measurement in film stretching mode with a frequency of 1 Hz, a heating rate of 3 °C / min, and a sample size of 30 mm × 5 mm × 1 mm.

[0074] The tensile properties were tested on dumbbell-shaped samples using an electronic universal mechanical testing machine (Z005-TH) with a sample size of 115 mm × 6 mm × 1 mm and a loading rate of 50 mm / min.

[0075] The self-healing efficiency is defined as the percentage of the scratch width healed after 2 hours of exposure to a specific ambient temperature (140-180°C) compared to the initial scratch width. The scratches on the sample surface were created with a 0.28mm-thick blade and kept to a depth of 0.5mm.

[0076] Among the polyurethane elastomers reported so far, the Tg Below 100℃, the self-repairing efficiency is also less than 100%. For example, the prior art has constructed a self-repairing polyurethane elastomer containing synergistic imine bonds and hydrogen bonds, which has a tensile strength of 4~7.5MPa, an elongation at break of 275~250%, a Tg of 25.4~38.8℃, and a T d5 The temperature of the elastomer is 287.7~316.9℃. Due to the presence of dynamic imine bonds and hydrogen bonds, the tensile strength of the elastomer sample can be repaired by heating it at 80℃ for 24 hours after being cut. The existing technology constructs a self-repairing polyurethane elastomer by introducing multiple hydrogen bonds and disulfide bonds, with a tensile strength of 17.9MPa and an elongation at break of 320%. T g The existing technology has constructed a polyurethane elastomer with synergistic effects of disulfide bonds and hydrogen bonds, and its tensile strength is 5~21MPa. T g The existing literature shows that the introduction of dynamic reversible covalent bonds and other non-covalent bond effects into the polyurethane self-healing system constructed by non-covalent bonds can improve the strength and heat resistance of polyurethane to a certain extent, but it is difficult to break through the application requirements of self-healing polyurethane elastomers in high temperature environments. Therefore, the preparation of high-strength self-healing polyurethane elastomers that can adapt to higher temperatures has great economic significance. At present, there are few elastomers with high Tg (higher than 140°C). The urethane elastomer of the present invention has both high strength and high self-healing properties, and not only has ultra-low temperature Tg, but also has a g (-52°C), also has ultra-high temperature T g (~226°C) and a high initial thermal decomposition temperature (~314°C), it has the performance to be used in both low and ultra-high temperature environments.

Claims

1. A method for preparing a heat-resistant self-repairing polyurethane elastomer, characterized in that: The method comprises the following steps: using 3,3'-diaminobenzidine and 3,3',4,4'-benzophenonetetracarboxylic dianhydride as raw materials, reacting in a first solvent to obtain a DTA solution; then adding a diisocyanate compound to react to obtain a DTA-NCO solution; then adding a second solvent, a polyol compound and a catalyst, performing a prepolymerization reaction and then heat treatment to obtain a heat-resistant, high-strength self-repairing polyurethane body; the molar ratio of 3,3'-diaminobenzidine, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, the diisocyanate compound, the polyol compound, the catalyst, the first solvent and the second solvent is 2: (0.8-1.2): (15-20): (1.25-3.25): (0.01-0.05): (100-160): (100-150).

2. The method for preparing the heat-resistant self-repairing polyurethane elastomer according to claim 1, characterized in that: When reacting in the first solvent, the reaction temperature is 80-100°C and the time is 0.5-2h to obtain a DTA solution, and the reaction temperature is 90-110°C and the time is 0.5-2h to obtain a DTA-NCO solution. In the second solvent, during the prepolymerization reaction, the reaction temperature is 70-90°C and the time is 0.5-2h. The heat treatment process is 40-60°C / 10-15h + 80-100°C / 4-6h.

3. The method for preparing the heat-resistant self-repairing polyurethane elastomer according to claim 1, characterized in that: The molar ratio of 3,3'-diaminobenzidine, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, diisocyanate compound, polyol compound, catalyst, first solvent and second solvent is 2:1:16: (1.25-3.25): (0.01-0.05): (100-160): (100-150).

4. The method for preparing the heat-resistant self-repairing polyurethane elastomer according to claim 1, characterized in that: The first solvent and the second solvent are independently selected from one or more of N,N-dimethylformamide, acetone, and ethanol; the catalyst includes one or more of organic tin and organic lead.

5. The heat-resistant self-repairing polyurethane elastomer prepared according to the preparation method of the heat-resistant self-repairing polyurethane elastomer according to claim 1.

6. The heat-resistant self-repairing polyurethane elastomer according to claim 5, characterized in that: The heat-resistant self-repairing polyurethane elastomer has a low-temperature glass transition temperature of less than -35°C and a high-temperature glass transition temperature of greater than 205°C.

7. A polyurethane elastomer material, the raw materials for its preparation include the heat-resistant self-healing polyurethane elastomer according to claim 5.

8. Use of the heat-resistant self-repairing polyurethane elastomer according to claim 5 in the preparation of polyurethane materials.

9. Use of the heat-resistant self-repairing polyurethane elastomer according to claim 5 in the preparation of self-repairing materials.

10. Use of the heat-resistant self-repairing polyurethane elastomer according to claim 5 in the preparation of aerospace materials.

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