A polyurethane material with photothermal self-repairing performance, a preparation method thereof and a 3D printing method

Abstract

The present application relates to a kind of polyurethane materials with photothermal self-repairing performance, the polyurethane material is prepared by diisocyanate, macromolecular dihydric alcohol, small molecule dihydric alcohol chain extender, photothermal agent, catalyst, solvent, it is used as 3D printing material. When 3D printing is carried out using the material, the photothermal performance of the material is used, the deposited layer is irradiated with light along the printing path in the FDM printing process, to improve the temperature of previous deposited layer, solve the problem of previous deposited layer rapid cooling in prior art;The temperature of previous deposited layer is improved, so as to activate the self-repairing performance of 3D printing material, then enhance the interlaminar bonding strength between adjacent filaments, and finally realize the mechanical enhancement and mechanical isotropy of FDM printing product.The polyurethane material of the present application helps to widen the practical application of FDM printing product in engineering field.

Description

Technical Field

[0001] This invention relates to the field of 3D printing, and more specifically, to a polyurethane material with photothermal self-healing properties, its preparation method, and a 3D printing method. Background Technology

[0002] 3D printing is an advanced molding technology that enables the rapid and direct creation of three-dimensional structures with complex features without the aid of molds, leading to its widespread application in numerous fields such as automotive, aerospace, and intelligent robotics. Fused deposition modeling (FDM) 3D printing technology has become one of the most widely used 3D printing technologies due to its ease of operation, low equipment cost, and high material compatibility. However, compared to traditional manufacturing techniques, while FDM technology can directly print products with complex structures, the mechanical properties of its printed products are relatively poor, typically significantly lower than those of products prepared using traditional manufacturing techniques. Furthermore, for FDM-printed products, the degree of interdiffusion and re-entanglement of polymer chains at the interfaces of adjacent filaments is crucial in determining their mechanical properties. However, due to the rapid cooling of previously deposited layers during the FDM printing process, when newly extruded molten material is deposited onto these cooled layers, it often results in incomplete diffusion and limited re-entanglement of polymer chains at the interfaces of adjacent filaments. Therefore, FDM printed products ultimately exhibit weak mechanical strength and mechanical anisotropy, especially the mechanical strength perpendicular to the deposition layer direction is significantly lower than in other directions, thus limiting the practical application of FDM printed products as fully functional components in the engineering field. Summary of the Invention

[0003] In view of the technical problems faced by FDM technology mentioned above, this invention provides a polyurethane material with photothermal self-healing properties to solve the technical problems of poor mechanical strength and mechanical anisotropy in printed products currently faced by FDM technology. First, a polyurethane material with self-healing properties is synthesized using molecular structure design. Second, a photothermal agent is introduced into the self-healing polyurethane through solution blending, thereby endowing the material with photothermal properties and preparing a polyurethane material with both photothermal and self-healing properties. Finally, the polyurethane material with both photothermal and self-healing properties is used as a 3D printing material. Utilizing the photothermal properties of the material, the deposited layer is irradiated with light along the printing path during the FDM printing process to increase the temperature of the previously deposited layer, solving the problem of rapid cooling of the previously deposited layer in the prior art. The increased temperature of the previously deposited layer activates the self-healing properties of the 3D printing material, thereby enhancing the interlayer bonding strength between adjacent filaments and ultimately achieving mechanical reinforcement of the FDM printed product.

[0004] One objective of this invention is to provide a polyurethane material with photothermal self-healing properties. The polyurethane material is prepared from diisocyanate, a macromolecular diol, a small-molecule diol chain extender, a photothermal agent, a catalyst, and a solvent. The molar ratio of the diisocyanate, the macromolecular diol, the small-molecule diol chain extender, and the catalyst is 100:15–60:60–85:0.1–1. Preferably, the molar ratio of the diisocyanate, the macromolecular diol, the small-molecule diol chain extender, and the catalyst is 100:15–40:65–85:0.2–0.8. The total weight ratio of the diisocyanate, the macromolecular diol, and the small molecule diol chain extender to the photothermal agent is 100:4-10. The small molecule diol chain extender is one or more of a disulfide-containing small molecule diol chain extender and / or an oxime-based diol chain extender. Those skilled in the art can select the appropriate molar ratio of the diisocyanate, the macromolecular diol, the small molecule diol chain extender, the photothermal agent, the catalyst, and the solvent according to actual needs.

[0005] In one preferred embodiment of the present invention, the diisocyanate is one or more selected from isoflurane diisocyanate, hexamethylene diisocyanate, diphenylmethane diisocyanate, toluene diisocyanate, terephthalic diisocyanate, 1,5-naphthalene diisocyanate, trimethylhexamethylene diisocyanate, and dicyclohexylmethane diisocyanate. Those skilled in the art can select a suitable type of diisocyanate according to actual needs.

[0006] In one preferred embodiment of the present invention, the macromolecular diol is one or more of hydroxyl-terminated polyester diols, hydroxyl-terminated polyether diols, hydroxyl-terminated polybutadiene, and polysiloxane diols; preferably, the hydroxyl-terminated polyester diol is one or more of polyadipate diol, polycarbonate diol, and polycaprolactone diol; or the hydroxyl-terminated polyether diol includes polytetramethylene ether diol and / or polypropylene oxide ether diol. Those skilled in the art can select appropriate types of macromolecular diols according to actual needs.

[0007] In one preferred embodiment of the present invention, the disulfide-bonded small-molecule glycol chain extender is 3,3′-dihydroxydiphenyl disulfide and / or bis(2-hydroxyethyl) disulfide; or the oxime-hydroxyl-containing small-molecule glycol chain extender is butanedione oxime and / or p-benzoquinone dioxime. Those skilled in the art can select the appropriate type of small-molecule glycol chain extender according to actual needs.

[0008] In one preferred embodiment of the present invention, the photothermal agent is an inorganic photothermal material and / or conjugated polymer nanoparticles; preferably, the inorganic photothermal material is one or more of graphene, carbon nanotubes, and gold nanorods; or the conjugated polymer nanoparticles are polydopamine and / or polyaniline. Those skilled in the art can select a suitable type of photothermal agent according to actual needs.

[0009] In one preferred embodiment of the present invention, the catalyst is one or more selected from dibutyltin dilaurate, triphenylbismuth, and triphenyltin chloride. The solvent is one or more selected from N,N-dimethylformamide, N,N-dimethylacetamide, tetrahydrofuran, and 1,4-dioxane. Those skilled in the art can select appropriate catalysts and solvents according to actual needs.

[0010] To meet the different performance requirements of polyurethane materials, such as mechanical strength, toughness, rheological properties, and glass transition temperature, technicians can select different macromolecular diols, diisocyanates, and small molecule diol chain extenders according to actual needs. They can also control photothermal performance by adjusting the content of photothermal agents and control the reaction rate by adjusting the type and feed ratio of catalysts.

[0011] A second objective of this invention is to provide a method for preparing a polyurethane material with photothermal self-healing properties, one of the objectives of this invention, the method comprising:

[0012] 1) Heating the macromolecular diol removes the water content from the macromolecular diol to obtain the first intermediate product;

[0013] 2) Cool the first intermediate product and add the diisocyanate to it to obtain an isocyanate-terminated polyurethane prepolymer;

[0014] 3) The small molecule diol chain extender and the catalyst are added to the isocyanate-terminated polyurethane prepolymer and heated to react, thereby obtaining the second intermediate product;

[0015] 4) The second intermediate product is cast into a mold and vacuum cured to obtain a polyurethane material with self-healing properties;

[0016] 5) Dissolve the self-healing polyurethane material in a solvent, add the photothermal agent, mix evenly, remove the solvent, and obtain the photothermal self-healing polyurethane material.

[0017] The following solutions can be adopted:

[0018] 1) Add the macromolecular diol to a reflux condenser and stir under vacuum at 120°C for 2 hours to completely remove the water contained in the macromolecular diol, which is the first intermediate product.

[0019] 2) The first intermediate product is cooled to a certain temperature, and the diisocyanate is added to the first intermediate product under a nitrogen atmosphere. The mixture is stirred and reacted for a period of time to obtain an isocyanate-terminated polyurethane prepolymer.

[0020] 3) Under a nitrogen atmosphere, the small molecule chain extender and catalyst are added to the isocyanate-terminated polyurethane prepolymer in step 2), heated to a certain temperature, stirred, and the second intermediate product is obtained when the viscosity of the reaction system increases to the point where it is about to climb the rod.

[0021] 4) The second intermediate product is cast into a polytetrafluoroethylene (PTFE) mold and cured in a vacuum oven to obtain a polyurethane material with self-healing properties.

[0022] 5) Dissolve the self-healing polyurethane material from step 4) into a solvent, add the photothermal agent, and mix thoroughly under high-speed stirring. Finally, remove the solvent to obtain the polyurethane material with photothermal self-healing properties.

[0023] In one preferred embodiment of the present invention, in step 1), the reaction temperature is 105–120°C and the reaction time is 1.5–2 h; in step 2), the reaction temperature is 50–90°C and the reaction time is 1–2 h; in step 3), the reaction temperature is 50–80°C and the reaction time is 1–3 h; in step 4), the vacuum curing temperature is 80–100°C and the vacuum curing time is 8–12 h. Those skilled in the art can select appropriate reaction time, vacuum curing time, and vacuum curing temperature according to actual needs.

[0024] The third objective of this invention is to provide a 3D printing method for a polyurethane material with photothermal self-healing properties, as described in one objective of this invention, or a polyurethane material with photothermal self-healing properties prepared by the method described in another objective of this invention, characterized in that:

[0025] The polyurethane material with photothermal self-healing properties was printed using a fused deposition modeling printer; during the printing process, near-infrared light was used to irradiate the deposited layer.

[0026] In one preferred embodiment of the present invention, the wavelength of the near-infrared light is 808–1100 nm, and the irradiation power is 0.3–1.0 W·cm⁻¹. -2 The irradiation time is 0.5 to 2 minutes. Technicians can adjust the irradiation power and irradiation time of the near-infrared light according to actual needs, thereby controlling the temperature of the previously deposited layer and obtaining 3D printed products with mechanical properties that meet the preset requirements and are mechanically isotropic.

[0027] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0028] 1. This invention uses macromolecular diols, diisocyanates, small-molecule diol chain extenders, photothermal agents, catalysts, and solvents as raw materials to design and synthesize a novel functional polyurethane material possessing both photothermal and self-healing properties, which is then used as a 3D printing material. When using this material for 3D printing, the photothermal properties of the material are utilized to irradiate the deposited layers along the printing path during FDM printing, thereby increasing the temperature of the previously deposited layers and solving the problem of rapid cooling of the previously deposited layers in existing technologies. The increased temperature of the previously deposited layers activates the self-healing properties of the 3D printing material, thereby enhancing the interlayer bonding strength between adjacent filaments and ultimately achieving mechanical reinforcement and mechanical isotropy in the FDM printed product. The polyurethane material of this invention helps to broaden the practical applications of FDM printed products in the engineering field.

[0029] 2. The polyurethane material of this invention, which combines photothermal and self-healing properties, has a self-healing temperature that is much lower than its melting and decomposition temperatures. Therefore, when using its photothermal properties to activate the material's self-healing properties to improve the interlayer bonding strength of FDM printed products, it is not necessary to heat the deposited layer to the melting temperature to achieve self-healing, thereby effectively avoiding damage to the printed product structure and degradation of the deposited material during the printing process.

[0030] 3. The polyurethane material with photothermal self-healing properties of the present invention has self-healing properties, which endows FDM printed products with self-repair capabilities and extends the service life of FDM printed products. Detailed Implementation

[0031] The present invention will now be described in detail with reference to specific embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention are still within the scope of protection of the present invention.

[0032] Example 1

[0033] Preparation of a polyurethane material with photothermal self-healing properties for 3D printing: 0.0175 mol of polycaprolactone diol (number average molecular weight approximately 2000) was added to a three-necked flask equipped with a mechanical stirrer and stirred under vacuum at 120°C for 2 hours to completely remove moisture from the polycaprolactone diol. Then, the reaction system was cooled to 60°C, and 0.0963 mol of diphenylmethane diisocyanate was added under a nitrogen atmosphere. The temperature was slowly increased to 80°C and reacted for 2 hours to obtain a polyurethane prepolymer. Then, 0.0788 mol of p-benzoquinone dioxime and 0.0005 mol of dibutyltin dilaurate catalyst were added to the polyurethane prepolymer and reacted at 70°C for 2 hours. When the viscosity of the reaction system reached a certain level, the reactants were cast into a polytetrafluoroethylene (PTFE) mold and cured in a vacuum oven at 100°C for 10 hours to obtain a polyurethane material with self-healing properties. The cured polyurethane material was then fully dissolved in 100 ml of N,N-dimethylformamide, followed by the addition of 2.8 g of graphene. The mixture was thoroughly stirred at high speed until homogeneous, and finally the solvent was removed, yielding a polyurethane material with photothermal and self-healing properties. It should be noted that in this embodiment, the weight of graphene is 4% of the total weight of the diisocyanate, the macromolecular diol, and the small-molecule diol chain extender.

[0034] A 3D printing method for polyurethane materials with photothermal self-healing properties: The polyurethane material with photothermal self-healing properties is printed using an FDM (Fused Deposition Modeling) printer. The printing temperature is 180℃, the printing speed is 10mm / s, and the printing platform temperature is 60℃. During the printing process, near-infrared light with a wavelength of 808nm is used to irradiate the deposited layer along the printing path, with an irradiation power of 0.6W·cm⁻¹. -2 This utilizes the photothermal effect of the polyurethane material to increase the temperature of the deposited layer, thereby activating the self-healing properties of the polyurethane material and ultimately improving the bonding strength between the deposited layers.

[0035] Example 2

[0036] Preparation of a polyurethane material with photothermal self-healing properties for 3D printing: 0.0193 mol of polytetramethylene ether glycol (number average molecular weight approximately 2000) was added to a three-necked flask equipped with a mechanical stirrer and stirred under vacuum at 115°C for 2 hours to completely remove moisture from the polytetramethylene ether glycol. Then, the reaction system was cooled to 75°C, and 0.0997 mol of isoflurane diisocyanate was added under a nitrogen atmosphere. The temperature was slowly increased to 80°C and reacted for 2 hours to obtain a polyurethane prepolymer. Next, 0.0804 mol of dimethylglyoxime and 0.0003 mol of dibutyltin dilaurate catalyst were added to the polyurethane prepolymer and reacted at 90°C for 2 hours. When the viscosity of the reaction system reached a certain level, the reactants were cast into a polytetrafluoroethylene (PTFE) mold and cured in a vacuum oven at 100°C for 10 hours to finally obtain a polyurethane material with self-healing properties. The cured polyurethane material was then fully dissolved in 100 ml of N,N-dimethylacetamide, followed by the addition of 3.5 g of carbon nanotubes. The mixture was thoroughly stirred at high speed until homogeneous, and finally the solvent was removed, yielding a polyurethane material with photothermal and self-healing properties. It should be noted that in this embodiment, the weight of the carbon nanotubes is 5% of the total weight of the diisocyanate, the macromolecular diol, and the small molecule diol chain extender.

[0037] A 3D printing method for polyurethane materials with photothermal self-healing properties: The polyurethane material with photothermal self-healing properties is printed using an FDM (Fused Deposition Modeling) printer. The printing temperature is 170℃, the printing speed is 10mm / s, and the printing platform temperature is 40℃. During the printing process, near-infrared light with a wavelength of 808nm is used to irradiate the deposited layer along the printing path, with an irradiation power of 0.6W·cm⁻¹. -2 This utilizes the photothermal effect of the polyurethane material to increase the temperature of the deposited layer, thereby activating the self-healing properties of the polyurethane material and ultimately improving the bonding strength between the deposited layers.

[0038] Example 3

[0039] Preparation of a polyurethane material with photothermal self-healing properties for 3D printing: 0.035 mol of polytetramethylene ether glycol (number average molecular weight approximately 1000) was added to a three-necked flask equipped with a mechanical stirrer and stirred under vacuum at 115°C for 2 hours to completely remove moisture from the polytetramethylene ether glycol. Then, the reaction system was cooled to 50°C, and 0.1046 mol of hexamethylene diisocyanate was added under a nitrogen atmosphere. The temperature was slowly increased to 60°C and reacted for 2 hours to obtain a polyurethane prepolymer. Then, 0.0696 mol of 3,3′-dihydroxydiphenyl disulfide and 0.0003 mol of dibutyltin dilaurate catalyst were added to the polyurethane prepolymer and reacted at 80°C for 2 hours. When the viscosity of the reaction system reached a certain level, the reactants were cast into a polytetrafluoroethylene (PTFE) mold and cured in a vacuum oven at 100°C for 10 hours to finally obtain a polyurethane material with self-healing properties. The cured polyurethane material was then fully dissolved in 100 ml of N,N-dimethylformamide, followed by the addition of 4.9 g of carbon nanotubes. The mixture was thoroughly stirred at high speed until homogeneous, and finally the solvent was removed, yielding a polyurethane material with photothermal and self-healing properties. It should be noted that in this embodiment, the weight of the carbon nanotubes was 5% of the total weight of the diisocyanate, the macromolecular diol, and the small molecule diol chain extender.

[0040] A 3D printing method for polyurethane materials with photothermal self-healing properties: The polyurethane material with photothermal self-healing properties is printed using an FDM (Fused Deposition Modeling) printer. The printing temperature is 190℃, the printing speed is 10mm / s, and the printing platform temperature is 60℃. During the printing process, near-infrared light with a wavelength of 808nm is used to irradiate the deposited layer along the printing path, with an irradiation power of 0.6W·cm⁻¹. -2 This utilizes the photothermal effect of the polyurethane material to increase the temperature of the deposited layer, thereby activating the self-healing properties of the polyurethane material and ultimately improving the bonding strength between the deposited layers.

[0041] Comparative Example 1

[0042] Preparation of self-healing polyurethane material for 3D printing: 0.0175 mol of polycaprolactone diol (number average molecular weight approximately 2000) was added to a three-necked flask equipped with a mechanical stirrer and stirred under vacuum at 120°C for 2 hours to completely remove moisture from the polycaprolactone diol. Then, the reaction system was cooled to 60°C, and 0.0963 mol of diphenylmethane diisocyanate was added under a nitrogen atmosphere. The temperature was slowly increased to 80°C and reacted for 2 hours to obtain a polyurethane prepolymer. Then, 0.0788 mol of p-benzoquinone dioxime and 0.0005 mol of dibutyltin dilaurate catalyst were added to the polyurethane prepolymer and reacted at 70°C for 2 hours. When the viscosity of the reaction system reached a certain level, the reactants were cast into a polytetrafluoroethylene (PTFE) mold and cured in a vacuum oven at 100°C for 10 hours to obtain a self-healing polyurethane material.

[0043] A 3D printing method for self-healing polyurethane material: The self-healing polyurethane material is printed using an FDM (Fused Deposition Modeling) printer. The printing temperature is 170℃, the printing speed is 10mm / s, and the printing platform temperature is 60℃. During the printing process, near-infrared light with a wavelength of 808nm is used to irradiate the deposited layer along the printing path, with an irradiation power of 0.6W·cm⁻¹. -2 .

[0044] The self-healing efficiency, melting temperature, glass transition temperature, tensile strength, and photothermal temperature of the polyurethane materials with photothermal self-healing properties prepared in Examples 1-3 and Comparative Example 1 were tested. The polyurethane materials prepared in Examples 1-3 and Comparative Example 1 were made into dumbbell-shaped standard tensile specimens (70mm × 4mm × 2mm) for testing. In the self-healing experiment, a scratch of approximately 1.5mm depth was cut into the dumbbell-shaped standard tensile specimen (70mm × 4mm × 2mm) using a blade. The specimen was then repaired at 100°C for 40 minutes, and the tensile strength of the repaired specimen was tested. The ratio of the tensile strength of the repaired specimen to that of the uncut specimen was defined as the self-healing efficiency. The melting temperature and glass transition temperature of the specimens were measured using differential scanning calorimetry (DSC). The tensile strength of the dumbbell-shaped standard tensile specimen (70mm × 4mm × 2mm) was measured using a universal testing machine at a tensile rate of 100mm / s. The photothermal temperature was measured using an infrared thermometer. The test results are shown in Table 1.

[0045] Table 1 shows the self-healing efficiency, melting temperature, glass transition temperature, tensile strength, and photothermal temperature of the polyurethane materials prepared in Examples 1-3 and Comparative Example 1.

[0046] Example 1 Example 2 Example 3 Comparative Example 1 Self-repair efficiency (100℃) / % 89.5 95.4 85.6 90.2 Melting temperature / °C 170 160 180 160 Glass transition temperature / °C -2.8 -12.5 22.4 -15.4 Tensile strength / MPa 29 27 41 24 <![CDATA[Photothermal temperature (0.6 W·cm -2 ) / ℃]]> 110 100 160 /

[0047] Tensile strength tests were conducted on the polyurethane materials prepared in Examples 1-3 and Comparative Example 1, using FDM printing to obtain products (sheets with the same thickness as the aforementioned dumbbell-shaped standard tensile specimens, also 2 mm thick). Specifically, the tensile strength was measured along the X-axis, Y-axis, and Z-axis. The tensile strength of the products was tested using a universal testing machine at a tensile rate of 100 mm / s. The test results are shown in Table 2.

[0048] Analysis of Table 2 shows that, compared with Comparative Example 1, the tensile strength of the polyurethane materials prepared in Examples 1-3, when printed using FDM, is significantly increased along the X, Y, and Z axes, indicating improved mechanical properties of the 3D printed products. Therefore, the polyurethane material with photothermal self-healing properties of this invention, when printed using FDM, significantly improves mechanical properties, effectively solving the technical defect of poor mechanical properties in current FDM printed products.

[0049] Table 2 shows the tensile strength of the polyurethane materials prepared in Examples 1-3 and Comparative Example 1, obtained by FDM printing.

[0050] Example 1 Example 2 Example 3 Comparative Example 1 Tensile strength along the X-axis / MPa 28.1 26.4 40.5 19.2 Tensile strength along the Y-axis / MPa 27.4 25.7 39.4 13.8 Tensile strength along the Z-axis / MPa 26.7 24.6 38.9 11.5

[0051] In summary, this invention simultaneously imparts photothermal and self-healing properties to thermoplastic polyurethane 3D printing materials, and utilizes the photothermal effect of the material during FDM printing to activate its self-healing properties, thereby effectively improving the mechanical properties of FDM printed products and achieving mechanical isotropy. This invention effectively solves the technical defect of poor mechanical properties in current FDM printed products, and will greatly broaden the practical application of FDM printed products in the engineering field.

Claims

1. Use of a polyurethane material having photothermal self-repairing properties in 3D printing, characterized in that: The polyurethane material is prepared from diisocyanate, macromolecular diol, small molecule diol chain extender, photothermal agent, catalyst, solvent; the molar ratio of the diisocyanate, the macromolecular diol, the small molecule diol chain extender, the catalyst is 100:15~40:65~85:0.2~0.8; the ratio of the total weight of the diisocyanate, the macromolecular diol, the small molecule diol chain extender and the weight of the photothermal agent is 100:4~10; the small molecule diol chain extender is a small molecule diol chain extender containing disulfide bond and / or a small molecule diol chain extender containing hydroxyl hydroxyl; the photothermal agent is one or more of graphene, carbon nanotube, gold nanorod; when the light-thermal performance of the polyurethane material is used to activate its self-healing performance to improve the interlayer bonding strength of the fused deposition modeling printed product, it is completely unnecessary to heat the deposited layer to the melting temperature to realize self-healing.

2. The use according to claim 1, characterized in that: The diisocyanate is one or more of isophorone diisocyanate, hexamethylene diisocyanate, diphenylmethane diisocyanate, toluene diisocyanate, p-phenylene diisocyanate, 1,5-naphthalene diisocyanate, trimethylhexamethylene diisocyanate, dicyclohexylmethane diisocyanate.

3. The use according to claim 1, characterized in that: The macromolecular diol is one or more of hydroxyl-terminated polyester diol, hydroxyl-terminated polyether diol, hydroxyl-terminated polybutadiene, polysiloxane type diol.

4. The use according to claim 3, characterized in that: The hydroxyl-terminated polyester diol is one or more of polyhexanedioic acid small molecule diol ester diol, polycarbonate diol, polycaprolactone diol; or The hydroxyl-terminated polyether diol includes polytetramethylene ether diol and / or polypropylene oxide ether diol.

5. The use according to claim 1, characterized in that: The small molecule diol chain extender containing disulfide bond is 3,3'-dihydroxydiphenyl disulfide and / or bis(2-hydroxyethyl)disulfide; or The small molecule diol chain extender containing hydroxyl hydroxyl is butanedione oxime and / or p-benzoquinone dioxime.

6. The use according to claim 1, characterized in that: The catalyst is one or more of dibutyltin dilaurate, triphenyl bismuth, chlorotriphenyltin; and / or The solvent is one or more of N,N-dimethylformamide, N,N-dimethylacetamide, tetrahydrofuran, 1,4-dioxane.

7. The use according to claim 1, wherein The polyurethane material is prepared by the following method: 1) The macromolecular diol is heated to remove the water in the macromolecular diol to obtain a first intermediate product; 2) The first intermediate product is cooled, and the diisocyanate is added to obtain an isocyanate-terminated polyurethane prepolymer; 3) The small molecule diol chain extender and the catalyst are added to the isocyanate-terminated polyurethane prepolymer, and heated to react to obtain a second intermediate product; 4) The second intermediate product is cast into a mold and vacuum cured to obtain a polyurethane material with self-repairing performance; 5) dissolving the polyurethane material with self-repairing performance in a solvent, adding the photothermal agent, mixing uniformly, and removing the solvent to obtain the polyurethane material with photothermal self-repairing performance.

8. The use according to claim 7, wherein: In step 1), the reaction temperature is 105-120℃, and the reaction time is 1.5-2h; and / or In step 2), the reaction temperature is 50-90℃, and the reaction time is 1-2h; and / or In step 3), the reaction temperature is 50-80℃, and the reaction time is 1-3h; and / or In step 4), the vacuum curing temperature is 80-100℃, and the vacuum curing time is 8-12h.

9. The use according to claim 1, characterized in that The steps for applying the polyurethane material to 3D printing include The polyurethane material with photothermal self-repairing performance is printed by using a fused deposition modeling printer; In the printing process, the deposited layer is irradiated by using near-infrared light.

10. The use according to claim 9, wherein: The wavelength of the near-infrared light is 808-1100 nm; the irradiation power is 808-965 W•cm -2 ; and the irradiation time is 0.5-2 min.