A self-healing polyurethane based on poly(oxytetramethylene) glycol and its preparation method and application

Abstract

The present invention provides a self-healing polyurethane based on poly(oxytetramethylene) glycol, a preparation method thereof and an application thereof. The raw materials for preparing the self-healing polyurethane include poly(oxytetramethylene) glycol, polyisocyanate, amino chain extender and metal salt; the molecular structure of the amino chain extender contains a nitrogen heterocyclic structure; the functionality of the amino chain extender is ≥2. In the present invention, the self-healing polyurethane has both high self-healing efficiency and good environmental resistance, and can still maintain good mechanical properties in a relatively harsh environment.

Description

Technical Field

[0001] The present invention belongs to the technical field of polyurethane materials, and particularly relates to a self-healing polyurethane based on poly(oxytetramethylene) glycol and a preparation method and application thereof. Background Art

[0002] Polyurethane elastomers have good mechanical properties, low-temperature resistance, wear resistance, and oil resistance, and are widely used in the fields of the automotive industry, footwear, aerospace, medical and health, construction, etc. Polyurethane materials have a unique microphase separation structure, and the molecular structures of their soft segments and hard segments have an important impact on the properties of polyurethane materials. Through molecular design, the functionalization and high performance of polyurethane materials can be realized. In actual use, polyurethanes often have to undergo external force damage or be used in harsh environments, such as humidity, strong acids, strong alkalis, high salts, etc. These working conditions pose high requirements for the environmental resistance of polyurethane materials. Existing polyurethane materials still cannot have both high self-healing efficiency and excellent environmental resistance.

[0003] For example, CN111763474A discloses a polyurethane transparent coating with high adhesion and environmental erosion resistance, including coating agent A and coating agent B; coating agent A includes polyol, chain extender, catalyst, bisphenol A epoxy resin, solvent, leveling agent, wetting agent, nano-titanium dioxide, and antibacterial agent; coating agent B includes aliphatic diisocyanate; the polyurethane can resist various environmental erosions; however, the polyurethane does not have self-healing properties. And among the polyurethanes with self-healing properties in the prior art, the environmental resistance is generally poor.

[0004] Therefore, developing a polyurethane material that has both high self-healing efficiency and excellent environmental resistance, and good mechanical properties at the same time, is an urgent problem to be solved in this field. Summary of the Invention

[0005] Aiming at the deficiencies of the existing technology, the purpose of the present invention is to provide a self-healing polyurethane based on poly(oxytetramethylene) glycol and a preparation method and application thereof. The self-healing polyurethane has good mechanical properties, high self-healing efficiency and good environmental resistance, and can be used in relatively harsh environments; it solves the problems of low self-healing efficiency of existing polyurethanes and poor use performance under harsh conditions.

[0006] To achieve this purpose, the present invention adopts the following technical solutions:

[0007] In the first aspect, the present invention provides a self-healing polyurethane based on poly(oxytetramethylene) glycol. The raw materials for preparing the self-healing polyurethane include poly(oxytetramethylene) glycol, polyisocyanate, amino chain extender, and metal salt; the molecular structure of the amino chain extender contains a nitrogen heterocyclic structure; the functionality of the amino chain extender is ≥2.

[0008] In the present invention, poly(oxytetramethylene) glycol has hydrophobic properties and a long carbon chain. Selecting poly(oxytetramethylene) glycol as the soft segment of the polyurethane is beneficial to improving the environmental resistance and mechanical properties of the polyurethane. Selecting an amino chain extender to form urea bonds with isocyanate groups, and at the same time, the metal salt coordinates with the nitrogen heterocycle of the amino chain extender, introducing coordination bonds into the hard segment, enhancing the hydrogen bond interaction between urea bonds. Through coordination and a large number of hydrogen bonds between urea bonds, not only does the polyurethane have self-healing properties, but also the self-healing effect of the polyurethane can be improved, and at the same time, the environmental resistance of the polyurethane can be improved. Further, the formation of coordination bonds will promote the aggregation of the hard segment, increasing the degree of phase separation between the hard and soft segments, and producing a synergistic effect with the flexibility of the long chain of poly(oxytetramethylene) glycol itself, so that the mechanical properties and self-healing efficiency of the polyurethane are further improved.

[0009] Preferably, the poly(oxytetramethylene) glycol is a homopolymer of oxytetramethylene.

[0010] Preferably, the average molecular weight of the poly(oxytetramethylene) glycol is 1000 - 3000 g / mol, for example, it can be 1000 g / mol, 1200 g / mol, 1400 g / mol, 1600 g / mol, 1800 g / mol, 2000 g / mol, 2200 g / mol, 2400 g / mol, 2600 g / mol, 2800 g / mol, 3000 g / mol, etc.

[0011] Preferably, the functionality of the polyisocyanate ≥ 2, for example, it can be 2, 3, 4, 5, 6, etc.

[0012] Preferably, the polyisocyanate includes any one or a combination of at least two of diphenylmethane diisocyanate, toluene diisocyanate, isophorone diisocyanate, 1,5-pentane diisocyanate, dicyclohexylmethane diisocyanate, hexamethylene diisocyanate, and xylylene diisocyanate; more preferably diphenylmethane diisocyanate.

[0013] Preferably, the molar ratio of the poly(oxytetramethylene) glycol to the polyisocyanate is 1:(1.5 - 10), where the specific values in (1.5 - 10) can be, for example, 1.5, 1.6, 1.8, 2, 2.2, 2.4, 2.6, 2.8, 3, 3.2, 3.5, 3.8, 4, 4.2, 4.5, 4.8, 5, 5.2, 5.5, 5.8, 6, 6.2, 6.5, 6.8, 7, 7.2, 7.5, 7.8, 8, 8.2, 8.5, 8.8, 9, 9.2, 9.5, 9.8, 10, etc.; more preferably 1:(2 - 5).

[0014] Preferably, the molar ratio of the amino chain extender to the poly(oxytetramethylene) glycol is 1:(1.5 - 10), where the specific values in (1.5 - 10) can be, for example, 1.5, 1.6, 1.8, 2, 2.2, 2.4, 2.6, 2.8, 3, 3.2, 3.5, 3.8, 4, 4.2, 4.5, 4.8, 5, 5.2, 5.5, 5.8, 6, 6.2, 6.5, 6.8, 7, 7.2, 7.5, 7.8, 8, 8.2, 8.5, 8.8, 9, 9.2, 9.5, 9.8, 10, etc.; more preferably 1:(5.5 - 8.5).

[0015] Preferably, the amino chain extender includes 2,6-diaminopyridine and / or 1,2-diaminoimidazole.

[0016] Preferably, the amino chain extender includes 2,6-diaminopyridine and 1,2-diaminoimidazole, and the molar ratio of 2,6-diaminopyridine to 1,2-diaminoimidazole is 1:(0.2 - 0.6), where the specific values in (0.2 - 0.6) can be, for example, 0.2, 0.22, 0.24, 0.26, 0.28, 0.3, 0.32, 0.34, 0.36, 0.38, 0.4, 0.42, 0.44, 0.46, 0.48, 0.5, 0.52, 0.54, 0.56, 0.58, 0.6, etc.

[0017] Preferably, the mass ratio of the metal salt to the amino chain extender is 1:(1 - 10), where the specific values in (1 - 10) can be, for example, 1, 1.2, 1.4, 1.5, 1.6, 1.8, 2, 2.2, 2.4, 2.6, 2.8, 3, 3.2, 3.5, 3.8, 4, 4.2, 4.5, 4.8, 5, 5.2, 5.5, 5.8, 6, 6.2, 6.5, 6.8, 7, 7.2, 7.5, 7.8, 8, 8.2, 8.5, 8.8, 9, 9.2, 9.5, 9.8, 10, etc.; more preferably 1:(2.5 - 4.5).

[0018] Preferably, the metal salt includes at least one of copper trifluoromethanesulfonate, zinc trifluoromethanesulfonate, iron trifluoromethanesulfonate, copper chloride, iron chloride, or zinc chloride.

[0019] In a second aspect, the present invention provides a method for preparing a self-healing polyurethane based on poly(oxytetramethylene) glycol according to the first aspect, and the preparation method includes the following steps:

[0020] (1) React poly(oxytetramethylene) glycol with polyisocyanate to obtain reactant A;

[0021] (2) React reactant A obtained in step (1) with an amino chain extender to obtain reactant B;

[0022] (3) React the reactant B obtained in step (2) with a metal salt to obtain the self-healing polyurethane.

[0023] In the present invention, before the reaction in step (1), there is also a step of removing water from the poly(oxytetramethylene) glycol and the polyisocyanate (the water removal can be carried out by drying); the water content of the poly(oxytetramethylene) glycol and the polyisocyanate is independently < 0.1 wt%.

[0024] Preferably, the reaction in step (1) is carried out in a protective atmosphere and in the presence of a catalyst.

[0025] Preferably, the protective atmosphere includes nitrogen.

[0026] Preferably, the catalyst includes dibutyltin dilaurate.

[0027] Preferably, the mass of the catalyst is 0.05 - 0.2 wt% of the total mass of the poly(oxytetramethylene) glycol and the polyisocyanate, and for example, it can be 0.05 wt%, 0.06 wt%, 0.08 wt%, 0.1 wt%, 0.12 wt%, 0.14 wt%, 0.16 wt%, 0.18 wt%, 0.2 wt%, etc.

[0028] Preferably, the temperature of the reaction in step (1) is 60 - 90 °C, and for example, it can be 60 °C, 65 °C, 70 °C, 75 °C, 80 °C, 85 °C, 90 °C, etc.

[0029] Preferably, the reaction time in step (1) is 2 - 8 h, and for example, it can be 2 h, 3 h, 4 h, 5 h, 6 h, 7 h, 8 h, etc.

[0030] Preferably, the reaction in step (2) is carried out in the presence of a solvent.

[0031] Preferably, the mass ratio of the amino chain extender to the solvent is 1:(5 - 15), and the specific values in (5 - 15) can be, for example, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, etc.

[0032] Preferably, the solvent includes N,N-dimethylformamide.

[0033] Preferably, the temperature of the reaction in step (2) is 60 - 90 °C, and for example, it can be 60 °C, 65 °C, 70 °C, 75 °C, 80 °C, 85 °C, 90 °C, etc.

[0034] Preferably, the reaction time in step (2) is 4 - 10 h, and for example, it can be 4 h, 5 h, 6 h, 7 h, 8 h, 9 h, 10 h, etc.

[0035] Preferably, the temperature of the reaction in step (3) is 40 to 80 °C, for example, it can be 40 °C, 45 °C, 50 °C, 55 °C, 60 °C, 65 °C, 70 °C, 75 °C, 80 °C, etc.

[0036] Preferably, the reaction time in step (3) is 4 to 10 h, for example, it can be 4 h, 5 h, 6 h, 7 h, 8 h, 9 h, 10 h, etc.

[0037] In the present invention, before the reaction in step (3), there is also a step of mixing the metal salt with the solvent; the mass ratio of the metal salt to the solvent is 1:(5 to 15), where the specific values in (5 to 15) can be, for example, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, etc.; the solvent includes N,N-dimethylformamide.

[0038] Preferably, after the reaction in step (3), there is also a drying step.

[0039] Preferably, the drying temperature is 60 to 100 °C, for example, it can be 60 °C, 65 °C, 70 °C, 75 °C, 80 °C, 85 °C, 90 °C, 95 °C, 100 °C, etc.; the drying time is 24 to 72 h, for example, it can be 24 h, 28 h, 32 h, 36 h, 40 h, 44 h, 48 h, 52 h, 56 h, 60 h, 64 h, 68 h, 72 h, etc.; the vacuum degree during drying is -0.08 to -0.1 MPa, for example, it can be -0.08 MPa, -0.082 MPa, -0.085 MPa, -0.088 MPa, -0.09 MPa, -0.092 MPa, -0.094 MPa, -0.096 MPa, -0.098 MPa, -0.1 MPa, etc.

[0040] As a preferred technical solution of the present invention, the preparation method includes:

[0041] (1) In the presence of a protective atmosphere, poly(oxytetramethylene) glycol, polyisocyanate and a catalyst are mixed and reacted at 60 to 90 °C for 2 to 8 h to obtain reactant A;

[0042] (2) The amino chain extender is mixed with the solvent, and then the obtained solution is reacted with reactant A at 60 to 90 °C for 4 to 10 h to obtain reactant B;

[0043] (3) Reactant B obtained in step (2) is reacted with the metal salt at 40 to 80 °C for 4 to 10 h, and then dried at 60 to 100 °C and -0.08 to -0.1 MPa for 24 to 72 h to obtain the self-healing polyurethane.

[0044] In the present invention, the preparation method of the polyurethane has mild conditions and a simple process.

[0045] In a third aspect, the present invention provides a self-healing material, which includes the self-healing polyurethane based on poly(oxytetramethylene) glycol described in the first aspect.

[0046] The numerical ranges described in the present invention not only include the above-listed point values, but also include any point values between the above numerical ranges not listed. Due to space limitations and for the sake of brevity, the specific point values included in the ranges of the present invention are not exhaustively listed herein.

[0047] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0048] For the self-healing polyurethane based on poly(oxytetramethylene) glycol provided by the present invention, the introduction of poly(oxytetramethylene) glycol endows the system with unique hydrophobic properties, enabling the polyurethane to have excellent tolerance in high-humidity, acid-base corrosion, and artificial seawater environments; a urethane bond is formed by using an amino chain extender with a specific structure and isocyanate. At the same time, a coordination bond is formed by the amino chain extender and metal salt, endowing the polyurethane with good self-healing performance and high healing efficiency, and also being beneficial to improving the environmental resistance of the polyurethane. The polyurethane provided by the present invention has a self-healing efficiency of ≥80% at 80 °C; a tensile strength of ≥6.7 MPa, and a tensile strength retention rate of ≥82% after immersion in artificial seawater; a tensile strength retention rate of ≥82% after immersion in acid (hydrochloric acid aqueous solution with pH = 2); a tensile strength retention rate of ≥81% after immersion in alkali (sodium hydroxide aqueous solution with pH = 12). Detailed Embodiments

[0049] The technical solutions of the present invention will be further described below through specific embodiments. Those skilled in the art should understand that the embodiments are only for helping to understand the present invention and should not be construed as specific limitations on the present invention.

[0050] All materials used in the present invention can be obtained through commercial purchase or prepared by conventional methods. Unless otherwise specified, the materials used in the present invention are as follows:

[0051] Poly(oxytetramethylene) glycol: with an average molecular weight of 2000 g / mol.

[0052] Example 1

[0053] This example provides a self-healing polyurethane. The raw materials for preparing the self-healing polyurethane include poly(oxytetramethylene) glycol, diphenylmethane diisocyanate, 2,6-diaminopyridine, and copper trifluoromethanesulfonate; the molar ratio of poly(oxytetramethylene) glycol to diphenylmethane diisocyanate is 1:2.2, and the molar ratio of 2,6-diaminopyridine to poly(oxytetramethylene) glycol is 1:6.5; the mass ratio of copper trifluoromethanesulfonate to 2,6-diaminopyridine is 1:3.

[0054] This embodiment provides a method for preparing self-healing polyurethane, which specifically includes the following steps:

[0055] (1) Add 20 g of poly(oxytetramethylene) glycol and 5.56 g of diphenylmethane diisocyanate into a three-necked flask, and then add 0.1 wt% of dibutyltin dilaurate based on the total mass of poly(oxytetramethylene) glycol and diphenylmethane diisocyanate. React for 3 h under a nitrogen atmosphere at a temperature of 70 °C to obtain reactant A.

[0056] (2) Subsequently, dissolve 2,6-diaminopyridine in N,N-dimethylformamide (the mass ratio of 2,6-diaminopyridine to N,N-dimethylformamide is 1:10). Add the obtained chain extender solution to reactant A obtained in step (1), and continue to react at 70 °C for 6 h to obtain reactant B.

[0057] (3) Dissolve copper trifluoromethanesulfonate in N,N-dimethylformamide (the mass ratio of copper trifluoromethanesulfonate to N,N-dimethylformamide is 1:5). Add the obtained metal salt solution to reactant B obtained in step (2), react at 60 °C for 6 h, then place it in a mold, and put it into a vacuum oven to dry at 80 °C for 24 h. After removing N,N-dimethylformamide, the self-healing polyurethane is obtained.

[0058] Example 2

[0059] This embodiment provides a self-healing polyurethane, the difference from Example 1 is only that the diphenylmethane diisocyanate is replaced with an equimolar amount of hexamethylene diisocyanate, and other raw materials, dosages, and preparation methods are the same as those in Example 1.

[0060] Example 3

[0061] This embodiment provides a self-healing polyurethane, the difference from Example 1 is only that the diphenylmethane diisocyanate is replaced with an equimolar amount of isophorone diisocyanate, and other raw materials, dosages, and preparation methods are the same as those in Example 1.

[0062] Example 4

[0063] This embodiment provides a self-healing polyurethane, the difference from Example 1 is only that the diphenylmethane diisocyanate is replaced with an equimolar amount of 1,5-pentane diisocyanate, and other raw materials, dosages, and preparation methods are the same as those in Example 1.

[0064] Example 5

[0065] This example provides a self-healing polyurethane. The raw materials for preparing the self-healing polyurethane include poly(oxytetramethylene) glycol, diphenylmethane diisocyanate, 2,6-diaminopyridine, and copper trifluoromethanesulfonate. The molar ratio of poly(oxytetramethylene) glycol to diphenylmethane diisocyanate is 1:4.5, and the molar ratio of 2,6-diaminopyridine to poly(oxytetramethylene) glycol is 1:8.5. The mass ratio of copper trifluoromethanesulfonate to 2,6-diaminopyridine is 1:4.5.

[0066] This example provides a method for preparing a self-healing polyurethane, and the specific steps are the same as those in Example 1.

[0067] Example 6

[0068] This example provides a self-healing polyurethane, and the difference from Example 1 is only that the content of 2,6-diaminopyridine is adjusted so that the molar ratio of 2,6-diaminopyridine to poly(oxytetramethylene) glycol is 1:3.5, and the other raw materials, dosages, and preparation methods are the same as those in Example 1.

[0069] Example 7

[0070] This example provides a self-healing polyurethane, and the difference from Example 1 is only that the content of 2,6-diaminopyridine is adjusted so that the molar ratio of 2,6-diaminopyridine to poly(oxytetramethylene) glycol is 1:12, and the other raw materials, dosages, and preparation methods are the same as those in Example 1.

[0071] Example 8

[0072] This example provides a self-healing polyurethane, and the difference from Example 1 is only that the content of copper trifluoromethanesulfonate is adjusted so that the mass ratio of copper trifluoromethanesulfonate to 2,6-diaminopyridine is 1:1.5, and the other raw materials, dosages, and preparation methods are the same as those in Example 1.

[0073] Example 9

[0074] This example provides a self-healing polyurethane, and the difference from Example 1 is only that the content of copper trifluoromethanesulfonate is adjusted so that the mass ratio of copper trifluoromethanesulfonate to 2,6-diaminopyridine is 1:7.5, and the other raw materials, dosages, and preparation methods are the same as those in Example 1.

[0075] Example 10

[0076] This example provides a self-healing polyurethane, and the difference from Example 1 is only that copper trifluoromethanesulfonate is replaced with an equal mass of zinc trifluoromethanesulfonate, and the other raw materials, dosages, and preparation methods are the same as those in Example 1.

[0077] Example 11

[0078] This example provides a self-healing polyurethane, which is only different from Example 1 in that copper trifluoromethanesulfonate is replaced with zinc chloride of equal mass, and other raw materials, dosages, and preparation methods are the same as those in Example 1.

[0079] Example 12

[0080] This example provides a self-healing polyurethane, which is only different from Example 1 in that 2,6-diaminopyridine is replaced with a mixture of 2,6-diaminopyridine and 1,2-diaminoimidazole with a molar ratio of 1:0.3 and equal mass, and other raw materials, dosages, and preparation methods are the same as those in Example 1.

[0081] Example 13

[0082] This example provides a self-healing polyurethane, which is only different from Example 1 in that 2,6-diaminopyridine is replaced with a mixture of 2,6-diaminopyridine and 1,2-diaminoimidazole with a molar ratio of 1:0.5 and equal mass, and other raw materials, dosages, and preparation methods are the same as those in Example 1.

[0083] Example 14

[0084] This example provides a self-healing polyurethane, which is only different from Example 1 in that 2,6-diaminopyridine is replaced with a mixture of 2,6-diaminopyridine and 1,2-diaminoimidazole with a molar ratio of 1:0.1 and equal mass, and other raw materials, dosages, and preparation methods are the same as those in Example 1.

[0085] Example 15

[0086] This example provides a self-healing polyurethane, which is only different from Example 1 in that 2,6-diaminopyridine is replaced with a mixture of 2,6-diaminopyridine and 1,2-diaminoimidazole with a molar ratio of 1:0.8 and equal mass, and other raw materials, dosages, and preparation methods are the same as those in Example 1.

[0087] Example 16

[0088] This example provides a self-healing polyurethane, which is only different from Example 1 in that 2,6-diaminopyridine is replaced with a mixture of 2,6-diaminopyridine and 2,4-diaminopyrimidine with a molar ratio of 1:0.3 and equal mass, and other raw materials, dosages, and preparation methods are the same as those in Example 1.

[0089] Comparative Example 1

[0090] This comparative example provides a self-healing polyurethane, which is different from Example 1 only in that poly(oxytetramethylene) glycol is replaced with polypropylene glycol (PPG2000) of equal average molecular weight, and other raw materials, dosages, and preparation methods are the same as those in Example 1.

[0091] Comparative Example 2

[0092] This comparative example provides a self-healing polyurethane, which is different from Example 1 only in that 2,6-diaminopyridine is replaced with an equimolar amount of 1,4-butanediol, and copper trifluoromethanesulfonate is not present in the preparation raw materials; in the preparation method, after the reaction in step (2) for 12 h, the resulting solution is placed in a mold and dried in a vacuum oven at 80 °C for 36 h. After removing N,N-dimethylformamide, the self-healing polyurethane is obtained, and other raw materials, dosages, and preparation methods are the same as those in Example 1.

[0093] Comparative Example 3

[0094] This comparative example provides a self-healing polyurethane, which is different from Example 1 only in that 2,6-diaminopyridine is replaced with an equimolar amount of 2,4-dihydroxypyridine, and other raw materials, dosages, and preparation methods are the same as those in Example 1.

[0095] Comparative Example 4

[0096] This comparative example provides a self-healing polyurethane, which is different from Example 1 only in that copper trifluoromethanesulfonate is not present in the preparation raw materials; in the preparation method, after the end of step (2), the resulting solution is placed in a mold and dried in a vacuum oven at 80 °C for 36 h. After removing N,N-dimethylformamide, the self-healing polyurethane is obtained, and other raw materials, dosages, and preparation methods are the same as those in Example 1.

[0097] Performance Test

[0098] (1) Tensile strength: The tensile mechanical properties of the self-healing polyurethanes provided in Examples 1-16 and Comparative Examples 1-4 were tested using an electronic universal testing machine at room temperature. The polyurethane samples were cut into dumbbell shapes. The gauge length of the dumbbell-shaped polyurethane was 12 mm (Lo), the width was 2 mm, and the thickness was 1.5 mm. The tensile rate was set at a constant strain rate of 100 mm / min. A 100 N load cell was used as the tensile mechanical sensor.

[0099] (2) Self-healing efficiency: After cutting the dumbbell-shaped polyurethane in half with a scalpel, the two parts of the polyurethane were brought into contact again and healed at 80 °C for 24 h without applying any external force to the sample during the process; the self-healing efficiency was represented by the tensile strength retention rate of the material before and after healing, and the test method for tensile strength was as described above. The calculation formula for the self-healing efficiency HE is as follows: where HE represents the self-healing efficiency, and σ self healed represents the tensile strength after healing, and σ original represents the initial tensile strength (i.e., the tensile strength of the material before self-healing).

[0100] (3) Environmental resistance: 50 mL of hydrochloric acid solution with pH = 2, sodium hydroxide solution with pH = 12, and artificial seawater (Shanghai Macklin Biochemical Co., Ltd., A769002) were respectively sucked into glass instruments. Subsequently, the prepared polyurethane samples were placed therein and soaked for 72 h. The soaked polyurethane was subjected to a tensile test according to method (1), and the environmental resistance was represented by the tensile strength retention rate of the material before and after soaking. The tensile strength retention rate CE was calculated according to the following formula: where CE represents the tensile strength retention rate, and σ corroded represents the tensile strength of the material after soaking, and σ original represents the initial tensile strength.

[0101] The specific test results are shown in Table 1.

[0102] Table 1

[0103]

[0104] As can be seen from Table 1, the self-healing polyurethane based on poly(oxytetramethylene) glycol provided by the present invention, through the selection of specific raw materials, namely, choosing poly(oxytetramethylene) glycol as the soft segment and introducing urea bonds and coordination bonds into the hard segment, the obtained polyurethane has good mechanical properties, high self-healing efficiency and good environmental corrosion resistance. The self-healing efficiency of the self-healing polyurethane reaches 80-99% after healing at 80 °C for 24 h; the tensile strength can reach 6.7-10.9 MPa, and the tensile strength retention rate after soaking in artificial seawater is 82-99%; the tensile strength retention rate after soaking in acid (hydrochloric acid aqueous solution with pH = 2) is 82-97%; the tensile strength retention rate after soaking in alkali (sodium hydroxide aqueous solution with pH = 12) is 81-98%.

[0105] By comparing Example 1, Example 2, Example 3 and Example 4, it can be seen that under the same conditions, the polyurethane prepared using diphenylmethane diisocyanate has higher mechanical strength and higher self-healing efficiency, and also has a higher tensile strength retention rate after being corroded by acid, alkali and artificial seawater.

[0106] By comparing Example 1 and Comparative Example 1, it can be seen that under the same reaction conditions, the polyurethane obtained by using poly(oxytetramethylene) glycol as a raw material has more excellent corrosion resistance and mechanical properties.

[0107] By comparing Example 1 with Comparative Examples 2 to 4, it can be seen that under the same conditions, using an amino chain extender with a specific structure and adding a metal salt to the preparation raw materials to form a coordination bond with the amino chain extender, the obtained polyurethane has higher self-healing efficiency and more excellent corrosion resistance.

[0108] In summary, through the selection of specific raw materials, the present invention can endow self-healing polyurethane with good mechanical properties, achieve excellent corrosion resistance of polyurethane, and improve the healing efficiency of self-healing polyurethane by using simple polymerization conditions and simple post-treatment.

[0109] The specific embodiments described above have further elaborated on the purpose, technical solutions, and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not used to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A self-healing polyurethane based on poly(oxytetramethylene) glycol, characterized in that, The raw materials for preparing the self-healing polyurethane include poly(oxytetramethylene) glycol, polyisocyanate, amino chain extender, and metal salt; The molecular structure of the amino chain extender contains a nitrogen heterocyclic structure; The functionality of the amino chain extender is ≥2; The polyisocyanate is selected from any one or a combination of at least two of diphenylmethane diisocyanate, toluene diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, and xylylene diisocyanate; The molar ratio of the amino chain extender to poly(oxytetramethylene) glycol is 1:(5.5~8.5); The mass ratio of the metal salt to the amino chain extender is 1:(2.5~4.5).

2. The self-healing polyurethane based on poly(oxytetramethylene) glycol according to claim 1, wherein The poly(oxytetramethylene) glycol is a homopolymer of oxytetramethylene.

3. The self-healing polyurethane based on poly(oxytetramethylene) glycol according to claim 1, characterized in that, The average molecular weight of the poly(oxytetramethylene) glycol is 1000~3000 g / mol.

4. The self-healing polyurethane based on poly(oxytetramethylene) glycol according to claim 1, wherein The functionality of the polyisocyanate is ≥2.

5. The self-healing polyurethane based on poly(oxytetramethylene) glycol according to claim 1, characterized in that, The molar ratio of the poly(oxytetramethylene) glycol to the polyisocyanate is 1:(1.5~10).

6. The self-healing polyurethane based on poly(oxytetramethylene) glycol according to claim 5, wherein The molar ratio of the poly(oxytetramethylene) glycol to the polyisocyanate is 1:(2~5).

7. The self-healing polyurethane based on poly(oxytetramethylene) glycol according to claim 1, characterized in that, The amino chain extender includes 2,6-diaminopyridine and / or 1,2-diaminoimidazole.

8. The self-healing polyurethane based on poly(oxytetramethylene) glycol according to claim 7, characterized in that, The amino chain extender includes 2,6-diaminopyridine and 1,2-diaminoimidazole, and the molar ratio of 2,6-diaminopyridine to 1,2-diaminoimidazole is 1:(0.2~0.6).

9. The self-healing polyurethane based on poly(oxytetramethylene) glycol according to claim 1, characterized in that, The metal salt includes at least one of copper trifluoromethanesulfonate, zinc trifluoromethanesulfonate, iron trifluoromethanesulfonate, copper chloride, iron chloride, or zinc chloride.

10. A method for preparing a self-healing polyurethane based on poly(oxytetramethylene) glycol according to any one of claims 1 to 9, characterized in that, The preparation method includes the following steps: (1) React poly(oxytetramethylene) glycol with polyisocyanate to obtain reactant A; (2) React reactant A obtained in step (1) with the amino chain extender to obtain reactant B; (3) React reactant B obtained in step (2) with the metal salt to obtain the self-healing polyurethane.

11. The preparation method according to claim 10, characterized in that, The reaction in step (1) is carried out in a protective atmosphere and in the presence of a catalyst.

12. The preparation method according to claim 11, wherein, The protective atmosphere includes nitrogen.

13. The preparation method according to claim 11, characterized in that, The catalyst includes dibutyltin dilaurate.

14. The preparation method according to claim 11, characterized in that, The mass of the catalyst is 0.05~0.2 wt% of the total mass of poly(oxytetramethylene) glycol and polyisocyanate.

15. The preparation method according to claim 10, characterized in that, The temperature of the reaction in step (1) is 60~90 °C.

16. The preparation method according to claim 10, characterized in that, The time of the reaction in step (1) is 2~8 h.

17. The preparation method according to claim 10, characterized in that, The reaction in step (2) is carried out in the presence of a solvent.

18. The preparation method according to claim 17, characterized in that, The mass ratio of the amino chain extender to the solvent is 1:(5~15).

19. The preparation method according to claim 17, characterized in that, The solvent includes N,N-dimethylformamide.

20. The preparation method according to claim 10, characterized in that, The temperature of the reaction in step (2) is 60~90 °C.

21. The preparation method according to claim 10, characterized in that, The time of the reaction in step (2) is 4~10 h.

22. The preparation method according to claim 10, wherein The temperature of the reaction in step (3) is 40~80 °C.

23. The preparation method according to claim 10, wherein, The time of the reaction in step (3) is 4~10 h.

24. The preparation method according to claim 10, wherein After the reaction in step (3), there is also a drying step.

25. The preparation method according to claim 24, wherein The drying temperature is 60~100 °C, the drying time is 24~72 h; the vacuum degree during drying is -0.08~-0.1 MPa.

26. A self-healing material, characterized in that, The self-healing material includes the self-healing polyurethane based on poly(oxytetramethylene) glycol according to any one of claims 1~9.

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