A method for preparing a self-healing waterborne polyurethane elastomer

Abstract

A method for preparing a self-repairable waterborne polyurethane elastomer, the present invention belongs to the technical field of self-repairing materials, and specifically relates to a method for preparing a polyurethane elastomer. The purpose of the present invention is to solve the problems of using a large amount of toxic organic solvents, long reaction time, high energy consumption and complicated preparation process in the polyurethane self-repairing materials prepared by the existing method. Method: 1. Reacting diisocyanate with deoxythymidine; 2. Adding polyether polyol, 2,2-dihydroxymethyl propionic acid and solvent; 3. Adding triethylamine; 4. Dispersing in distilled water containing a chain extender; 5. Curing to obtain a self-repairable waterborne polyurethane elastomer. The waterborne polyurethane elastomer prepared by the present invention is repaired at 110°C for 4h or at room temperature with a trace amount of solvent for 6h, and its repair efficiency can reach more than 85% or more than 90%; and the solvent-repaired polyurethane elastomer not only has a high elongation at break, but also has mechanical properties comparable to the original polyurethane elastomer.

Description

Technical Field

[0001] The invention belongs to the technical field of self-repairing materials, and in particular relates to a method for preparing a polyurethane elastomer. Background Art

[0002] Today, the use of elastomer materials is becoming more and more widespread in the world. Polyurethane material is an excellent elastomer with light weight, high strength and high ductility. It has a wide range of application prospects in medical devices, electronic skin, military materials, coatings and household appliances. Due to its excellent mechanical properties, the use of polyurethane materials has continued to increase in recent years. However, polyurethane materials will suffer irreversible damage over time, resulting in a large number of microcracks or even fractures, which not only poses a safety hazard in some fields, but also leads to a large amount of waste polyurethane every year. Therefore, how to repair cracks in time when they are discovered, extend the service life of the material, and reduce the generation of waste is an important issue that needs to be solved today.

[0003] Polyurethane self-healing materials have made significant research progress in recent years. Researchers have introduced repairable microcapsules, reversible covalent bonds (such as disulfide bonds, amide bonds, diselenide bonds, etc.), hydrogen bonds, coordination bonds, etc. into polymer matrices or molecular chains, and repaired the damaged parts of polyurethane materials under the stimulation of external environments (such as light, heat, solvents, etc.). Patent CN 113831493 A discloses a self-healing polyurethane elastomer containing six-fold intermolecular hydrogen bonds. The preparation process of the polyurethane elastomer is simple. 2,6-diaminopyridine or a derivative of 2,6-diaminopyridine is used as a chain extender. The prepared polyurethane elastomer has good mechanical properties, but because a large amount of solvents such as tetrahydrofuran, N,N-dimethylformamide or methanol are used in the preparation process of this elastomer, it has greater toxicity. Patent CN 110698635 B discloses a polyurethane elastomer with high toughness and high mechanical strength that can be recycled and self-repaired and a preparation method thereof, which improves the elasticity and repair performance of polyurethane by combining hydrogen bonds and coordination bonds. Although the synthesized polyurethane has high mechanical strength and healing properties, it has a long reaction time (>48h), high energy consumption and a complex preparation process. Summary of the invention

[0004] The purpose of the present invention is to solve the problems of using a large amount of toxic organic solvents, long reaction time, high energy consumption and complicated preparation process in the polyurethane self-healing material prepared by the existing method, and to provide a method for preparing a self-healing water-based polyurethane elastomer.

[0005] A method for preparing a self-repairable waterborne polyurethane elastomer is specifically completed by the following steps:

[0006] 1. Under the protection of inert gas, react diisocyanate with deoxythymidine at 25°C to 50°C to obtain reaction product I;

[0007] 2. Add polyether polyol to the reaction product I, raise the temperature to 70°C to 85°C, react at 70°C to 85°C for a period of time, then add 2,2-dimethylol propionic acid and a solvent, continue to react at 70°C to 85°C for a period of time to obtain a polyurethane prepolymer;

[0008] 3. Lowering the temperature of the polyurethane prepolymer to 40°C to 45°C, then adding triethylamine, and continuing to react at 40°C to 45°C for a period of time to obtain a prepolymer;

[0009] Fourth, firstly, dispersing the chain extender in distilled water, and then dispersing the prepolymer obtained in step 3 in distilled water to obtain an aqueous polyurethane emulsion;

[0010] 5. Put the water-based polyurethane emulsion into a polytetrafluoroethylene mold, and then cure it at room temperature. After curing, dry it to obtain a self-repairing water-based polyurethane elastomer.

[0011] Beneficial effects of the present invention:

[0012] 1. The present invention discloses a method for preparing a high-strength, high-strength, repairable biomimetic waterborne polyurethane elastomer (a self-repairable waterborne polyurethane elastomer) realized by multiple hydrogen bonds. The preparation process is simple, and only a small amount of organic solvent is required during the synthesis process, which reduces the residual solvent rate in the product and is green and environmentally friendly. The synthesized waterborne polyurethane not only has high mechanical strength and repairability, but also has good elasticity, thermal stability, etc.

[0013] 2. The present invention discloses a method for preparing a high-strength, high-strength, repairable biomimetic waterborne polyurethane elastomer (a self-repairable waterborne polyurethane elastomer) realized by multiple hydrogen bonds, wherein the polyurethane still has good resilience after repeated stretching, and the repaired polyurethane also has good stretchability and resilience;

[0014] 3. The present invention discloses a method for preparing a high-strength, high-strength repairable bionic water-based polyurethane elastomer (a self-repairable water-based polyurethane elastomer) realized by multiple hydrogen bonds. The polyurethane is repaired at 110°C for 4 hours or at room temperature with a trace amount of solvent for 6 hours, and the repair efficiency can reach more than 85% or more than 90%; and the solvent-repaired polyurethane elastomer not only has a high elongation at break, but also has mechanical properties comparable to those of the original polyurethane elastomer;

[0015] 4. The present invention discloses a method for preparing a high-strength, high-strength repairable biomimetic waterborne polyurethane elastomer (a self-repairable waterborne polyurethane elastomer) realized by multiple hydrogen bonds, wherein the glass transition temperature (Tg) of the polyurethane elastomer is less than -30°C, so the polyurethane elastomer can maintain high elasticity even in an environment below 0°C;

[0016] 5. The present invention discloses a method for preparing a high-strength, high-strength repairable bionic water-based polyurethane elastomer (a self-repairable water-based polyurethane elastomer) achieved by multiple hydrogen bonds. The polyurethane has high transparency and expands its application range. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a reaction mechanism diagram of the self-healing waterborne polyurethane elastomer prepared in Example 1;

[0018] Figure 2 The stress-strain curves of the self-repairable waterborne polyurethane elastomer prepared in Example 1 before and after high-temperature repair, where 1 is before repair and 2 is after repair;

[0019] Figure 3 The stress-strain curves of the self-repairable waterborne polyurethane elastomer prepared in Example 1 before and after solvent repair, where 1 is before repair and 2 is after repair;

[0020] Figure 4 This is an infrared graph of the self-healing waterborne polyurethane elastomer prepared in Example 1;

[0021] Figure 5 Polarized microscope images of the self-healing waterborne polyurethane elastomer prepared in Example 1 before and after high-temperature repair and solvent repair. DETAILED DESCRIPTION

[0022] Specific implementation method 1: This implementation method is a method for preparing a self-repairable waterborne polyurethane elastomer, which is specifically completed according to the following steps:

[0023] 1. Under the protection of inert gas, react diisocyanate with deoxythymidine at 25°C to 50°C to obtain reaction product I;

[0024] 2. Add polyether polyol to the reaction product I, raise the temperature to 70°C to 85°C, react at 70°C to 85°C for a period of time, then add 2,2-dimethylol propionic acid and a solvent, continue to react at 70°C to 85°C for a period of time to obtain a polyurethane prepolymer;

[0025] 3. Lowering the temperature of the polyurethane prepolymer to 40°C to 45°C, then adding triethylamine, and continuing to react at 40°C to 45°C for a period of time to obtain a prepolymer;

[0026] Fourth, firstly, dispersing the chain extender in distilled water, and then dispersing the prepolymer obtained in step 3 in distilled water to obtain an aqueous polyurethane emulsion;

[0027] 5. Put the water-based polyurethane emulsion into a polytetrafluoroethylene mold, and then cure it at room temperature. After curing, dry it to obtain a self-repairing water-based polyurethane elastomer.

[0028] Specific embodiment 2: This embodiment differs from specific embodiment 1 in that the diisocyanate in step 1 is aromatic isocyanate, aliphatic isocyanate or alicyclic isocyanate. The other steps are the same as those in specific embodiment 1.

[0029] Specific embodiment 3: This embodiment differs from specific embodiment 1 or 2 in that the molar ratio of diisocyanate to deoxythymidine in step 1 is (6-20):1; the reaction time in step 1 is 1h-3h. The other steps are the same as those in specific embodiment 1 or 2.

[0030] Specific embodiment 4: This embodiment differs from specific embodiments 1 to 3 in that: the solvent in step 2 is acetone, butanone or N-methylpyrrolidone; the molar ratio of the polyether polyol in step 2 to the deoxythymidine in step 1 is (1 to 5):1; the molar ratio of the polyether polyol in step 2 to 2,2-dihydroxymethylpropionic acid is 1:(0.5 to 1); the molar ratio of the solvent in step 2 to 2,2-dihydroxymethylpropionic acid is (10 to 60):1. The other steps are the same as those in specific embodiments 1 to 3.

[0031] Specific embodiment 5: This embodiment differs from specific embodiments 1 to 4 in that: in step 2, polyether polyol is added to the reaction product I, the temperature is raised to 70°C to 85°C, the reaction is carried out at 70°C to 85°C for 1h to 4h, 2,2-dimethylol propionic acid is added, and the reaction is continued at 70°C to 85°C for 1h to 3h to obtain a polyurethane prepolymer. The other steps are the same as those of specific embodiments 1 to 4.

[0032] Specific embodiment 6: This embodiment differs from specific embodiments 1 to 5 in that the molar ratio of the triethylamine in step 3 to the 2,2-dimethylol propionic acid in step 2 is 1:1. In step 3, the temperature of the polyurethane prepolymer is lowered to 40°C to 45°C, and then triethylamine is added, and the reaction is continued at 40°C to 45°C for 20min to 30min to obtain a reaction product II. The other steps are the same as those of specific embodiments 1 to 5.

[0033] Specific embodiment 7: This embodiment differs from specific embodiments 1 to 6 in that: the chain extender described in step 4 is 1,2-ethylenediamine, 1,4-butanediol, isophoronediamine or triethylenetetramine; the 2,2-dimethylolpropionic acid and polyether polyol are dried and dehydrated before use. The other steps are the same as those of specific embodiments 1 to 6.

[0034] Specific embodiment 8: This embodiment differs from specific embodiments 1 to 7 in that the molar ratio of the chain extender in step 4 to the deoxythymidine in step 1 is 1:(0.5-1.5); the solid content of the aqueous polyurethane emulsion in step 4 is 30%-40%. The other steps are the same as those of specific embodiments 1 to 7.

[0035] Specific embodiment 9: This embodiment differs from specific embodiments 1 to 8 in that the curing time in step 5 is 12 hours to 48 hours, the drying temperature in step 5 is 50°C to 83°C, and the drying time is 8 hours to 24 hours. The other steps are the same as those in specific embodiments 1 to 8.

[0036] Specific embodiment 10: This embodiment differs from specific embodiments 1 to 9 in that the self-repairable waterborne polyurethane elastomer described in step 5 includes a hard segment and a soft segment, the soft segment is a polyether polyol with a molecular weight Mw=2000-4500 g / mol, the hard segment is isophorone diisocyanate, and the molar ratio of the hard segment to the soft segment is (1-2): 1. The other steps are the same as specific embodiments 1 to 9.

[0037] The following examples are used to verify the beneficial effects of the present invention:

[0038] Example 1: A method for preparing a self-repairable waterborne polyurethane elastomer is specifically completed by the following steps:

[0039] 1. Under the protection of inert gas, 10.27 g of isophorone diisocyanate (IPDI) and 1.02 g of deoxythymidine (2-Td) were reacted at 30°C for 1.5 h to obtain reaction product Ⅰ;

[0040] 2. Add 30 g of polyether polyol (PPG) to the reaction product I, raise the temperature to 80°C, react at 80°C for 1 hour, then add 1.87 g of 2,2-dimethylol propionic acid (DMPA) and 10 mL of 2-butanone, and continue to react at 80°C for 2 hours to obtain a polyurethane prepolymer;

[0041] 3. Lower the temperature of the polyurethane prepolymer to 45°C, then add 1.42g of triethylamine, and continue to react at 45°C for 30min to obtain a prepolymer;

[0042] 4. First, 0.85 g of isophorone diamine was dispersed in distilled water, and then the prepolymer obtained in step 3 was dispersed in distilled water to obtain an aqueous polyurethane emulsion with a solid content of 30%;

[0043] 5. Place the water-based polyurethane emulsion into a polytetrafluoroethylene mold, cure it at room temperature for 48 hours, and then place it in an oven at 70°C for 12 hours to obtain a self-repairing water-based polyurethane elastomer.

[0044] Figure 1 This is a reaction mechanism diagram of the self-healing waterborne polyurethane elastomer prepared in Example 1;

[0045] The self-repairable waterborne polyurethane elastomer prepared in Example 1 was cut with scissors, and then the cross sections were contacted, and then the contacted cross sections were repaired at 110°C for 4 hours. The stress-strain curves before and after high temperature repair are shown in FIG. Figure 2 As shown;

[0046] from Figure 2 It can be seen that the maximum tensile stress of the self-repairable waterborne polyurethane elastomer prepared in Example 1 is 25.2 MPa, the maximum tensile strain is 1269%, and the repair efficiency is 82% when repaired at high temperature.

[0047] The self-repairable waterborne polyurethane elastomer prepared in Example 1 was cut with scissors, a layer of anhydrous ethanol was sprayed on the cross section, and it was placed at room temperature for 6 hours. The stress-strain curves before and after solvent repair are shown in FIG. Figure 3 As shown;

[0048] Figure 3 The stress-strain curves of the self-repairable waterborne polyurethane elastomer prepared in Example 1 before and after solvent repair, where 1 is before repair and 2 is after repair;

[0049] from Figure 3 It can be seen that at room temperature, the repair efficiency is 95% after repair with a small amount of solvent.

[0050] Figure 4 This is an infrared graph of the self-healing waterborne polyurethane elastomer prepared in Example 1;

[0051] from Figure 4 It can be seen that at 3500cm -1 and 2270cm -1 No -OH and -NCO peaks were found at 3302 cm -1 and 3377cm -1 Department-NH 2 The double peaks disappeared. 3327cm -1 The absorption peak of -NH- is at 1713cm -1 The C=O stretching vibration is at 1640 cm-1 The absorption peak of hydrogenated -C=O is shown at 1531 cm -1 The position is the NH bending vibration of the carbamate or amide group, indicating that the self-repairable waterborne polyurethane elastomer chain structure of Example 1 was successfully constructed.

[0052] Figure 5 Polarized microscope images of the self-healing waterborne polyurethane elastomer prepared in Example 1 before and after high-temperature repair and solvent repair;

[0053] from Figure 5 It can be seen that the cross section of the elastomer can be repaired under high temperature or solvent conditions, and the cross section marks disappear after repair.

[0054] Example 2: A method for preparing a self-repairable waterborne polyurethane elastomer is specifically completed by the following steps:

[0055] 1. Under the protection of inert gas, 10.53 g of 4,4'-dicyclohexylmethane diisocyanate (HMDI) and 1.47 g of deoxythymidine (2-Td) were reacted at 30°C for 1.5 h to obtain reaction product Ⅰ;

[0056] 2. Add 30 g of polyether polyol (PPG) to the reaction product I, raise the temperature to 80°C, react at 80°C for 1 hour, then add 1.87 g of 2,2-dimethylol propionic acid (DMPA) and 10 mL of acetone, and continue to react at 80°C for 2 hours to obtain a polyurethane prepolymer;

[0057] 3. Lower the temperature of the polyurethane prepolymer to 45°C, then add 1.42g of triethylamine, and continue to react at 45°C for 30min to obtain a prepolymer;

[0058] 4. First, 0.56 g of triethylenetetramine was dispersed in distilled water, and then the prepolymer obtained in step 3 was dispersed in distilled water to obtain an aqueous polyurethane emulsion with a solid content of 30%;

[0059] 5. Place the water-based polyurethane emulsion into a polytetrafluoroethylene mold, cure it at room temperature for 48 hours, and then place it in an oven at 70°C for 12 hours to obtain a self-repairing water-based polyurethane elastomer.

[0060] Example 3: A method for preparing a self-repairable waterborne polyurethane elastomer is specifically completed according to the following steps:

[0061] 1. Under the protection of inert gas, 9.58 g of hexamethylene diisocyanate (HDI) and 0.80 g of deoxythymidine (2-Td) were reacted at 30°C for 1.5 h to obtain reaction product Ⅰ;

[0062] 2. Add 30 g of polyether polyol (PPG) to the reaction product I, raise the temperature to 80°C, react at 80°C for 1 hour, then add 1.87 g of 2,2-dimethylol propionic acid (DMPA) and 10 mL of N-methylpyrrolidone (NMP), and continue to react at 80°C for 2 hours to obtain a polyurethane prepolymer;

[0063] 3. Lower the temperature of the polyurethane prepolymer to 45°C, then add 1.42 g of triethylamine, and continue to react at 45°C for 0.5 h to obtain a prepolymer;

[0064] 4. First, 0.13 g of 1,2-ethylenediamine was dispersed in distilled water, and then the prepolymer obtained in step 3 was dispersed in distilled water to obtain an aqueous polyurethane emulsion with a solid content of 30%;

[0065] 5. Place the water-based polyurethane emulsion into a polytetrafluoroethylene mold, cure it at room temperature for 48 hours, and then place it in an oven at 70°C for 12 hours to obtain a self-repairing water-based polyurethane elastomer.

[0066] The self-repairable waterborne polyurethane elastomers prepared in Example 2 and Example 3 can repair the elastomer cross-section under high temperature or solvent conditions, and the cross-section marks disappear after repair.

Claims

1. A method for preparing a self-repairable waterborne polyurethane elastomer, characterized in that The preparation method is specifically completed according to the following steps:

1. Under the protection of inert gas, react diisocyanate with deoxythymidine at 25°C to 50°C to obtain reaction product I; The molar ratio of diisocyanate to deoxythymidine in step 1 is (6-20):1; 2. Add polyether polyol to the reaction product I, raise the temperature to 70°C to 85°C, react at 70°C to 85°C for a period of time, then add 2,2-dimethylol propionic acid and a solvent, continue to react at 70°C to 85°C for a period of time to obtain a polyurethane prepolymer; The molar ratio of the polyether polyol described in step 2 to the deoxythymidine described in step 1 is (1-5):1; 3. Lowering the temperature of the polyurethane prepolymer to 40°C to 45°C, then adding triethylamine, and continuing to react at 40°C to 45°C for a period of time to obtain a prepolymer; Fourth, firstly, dispersing the chain extender in distilled water, and then dispersing the prepolymer obtained in step 3 in distilled water to obtain an aqueous polyurethane emulsion; 5. Put the water-based polyurethane emulsion into a polytetrafluoroethylene mold, and then cure it at room temperature. After curing, dry it to obtain a self-repairing water-based polyurethane elastomer.

2. The method for preparing a self-repairable waterborne polyurethane elastomer according to claim 1, characterized in that The diisocyanate described in step 1 is aromatic isocyanate, aliphatic isocyanate or alicyclic isocyanate.

3. The method for preparing a self-repairable waterborne polyurethane elastomer according to claim 1, characterized in that The reaction time in step 1 is 1 h to 3 h.

4. The method for preparing a self-repairable waterborne polyurethane elastomer according to claim 1, characterized in that The solvent described in step 2 is acetone, butanone or N-methylpyrrolidone; the molar ratio of the polyether polyol described in step 2 to 2,2-dihydroxymethylpropionic acid is 1:(0.5-1); the molar ratio of the solvent described in step 2 to 2,2-dihydroxymethylpropionic acid is (10-60):

1.

5. The method for preparing a self-repairable waterborne polyurethane elastomer according to claim 1, characterized in that In step 2, polyether polyol is added to the reaction product I, the temperature is raised to 70°C to 85°C, the reaction is carried out at 70°C to 85°C for 1h to 4h, 2,2-dihydroxymethylpropionic acid is added, and the reaction is continued at 70°C to 85°C for 1h to 3h to obtain a polyurethane prepolymer.

6. The method for preparing a self-repairable waterborne polyurethane elastomer according to claim 1, characterized in that The molar ratio of the triethylamine described in step three to the 2,2-dihydroxymethylpropionic acid described in step two is 1:

1. In step three, the temperature of the polyurethane prepolymer is lowered to 40°C to 45°C, and then triethylamine is added, and the reaction is continued at 40°C to 45°C for 20min to 30min to obtain reaction product II.

7. The method for preparing a self-repairable waterborne polyurethane elastomer according to claim 1, characterized in that The chain extender described in step 4 is 1,2-ethylenediamine, 1,4-butanediol, isophoronediamine or triethylenetetramine; the 2,2-dihydroxymethylpropionic acid and polyether polyol are dried and dehydrated before use.

8. The method for preparing a self-repairable waterborne polyurethane elastomer according to claim 1, characterized in that The molar ratio of the chain extender in step 4 to the deoxythymidine in step 1 is 1:(0.5-1.5); the solid content of the aqueous polyurethane emulsion in step 4 is 30%-40%.

9. The method for preparing a self-repairable waterborne polyurethane elastomer according to claim 1, characterized in that The curing time described in step 5 is 12h to 48h; the drying temperature described in step 5 is 50°C to 83°C, and the drying time is 8h to 24h.

10. The method for preparing a self-repairable waterborne polyurethane elastomer according to claim 1, characterized in that The self-healing waterborne polyurethane elastomer described in step five includes a hard segment and a soft segment. The soft segment is a polyether polyol with a molecular weight Mw of 2000 to 4500 g / mol. The hard segment is isophorone diisocyanate. The molar ratio of the hard segment to the soft segment is (1 to 2):1.

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