Self-healing polyurethane elastomer, its preparation method and application

Abstract

The application provides a self-repairing polyurethane elastomer, raw materials for preparing the self-repairing polyurethane elastomer include, in terms of mass percentage, polyether polyol 57-67%, m-xylylene diisocyanate 25-30% and butanedione oxime 7-12%. The m-xylylene diisocyanate is a new type of isocyanate, has the advantages of high activity and fast reaction speed, and the self-repairing polyurethane elastomer obtained by reacting the m-xylylene diisocyanate with the butanedione oxime has a light transmittance of more than 90%, the tensile strength and the elongation at break are respectively up to 34.5 MPa and 1130%, and the self-repairing efficiency of the tensile strength is greater than 99%.

Description

Technical Field

[0001] This invention belongs to the field of functional polyurethane technology, specifically relating to a self-healing polyurethane elastomer, its preparation method, and its application. Background Technology

[0002] Self-healing materials, as a novel type of functional material, have broad application prospects in fields such as electronic instruments, surface protection, automobiles, biomedicine, and smart materials. Self-healing is divided into exogenous self-healing and intrinsic self-healing. Intrinsic self-healing is further divided into reversible non-covalent and reversible covalent self-healing. Dynamic reversible reactions can achieve the repair process without the addition of external repair agents or monomers, and because the reaction is reversible, it can undergo multiple repairs, attracting considerable interest from researchers. Polyurethane materials, due to their excellent properties, are often used as matrix materials in self-healing systems.

[0003] CN108314763A prepared dynamically repairable polyurethane at room temperature and without a catalyst using multifunctional oximes. Although the use of a catalyst was avoided, the recovery efficiency was only 85%, which does not meet the requirements for material use in many situations. CN108503782A developed a colorless and transparent self-healing thermoplastic polyurethane elastomer (TPU) film using dimethylglyoxime (DMG) as a chain extender. It has adjustable mechanical strength, self-healing ability and good transparency, but the long-term optical stability of the film still needs to be studied and clarified. Therefore, obtaining a self-healing elastomer with good mechanical properties and optical stability remains a challenging issue.

[0004] Existing self-healing polyurethane elastomers suffer from low repair efficiency, yellowing appearance, and poor mechanical properties. Therefore, developing a self-healing polyurethane elastomer with high self-healing efficiency, minimal yellowing appearance, and excellent mechanical properties to meet the application needs of self-healing polyurethane elastomers in electronic instruments, surface protection, automobiles, biomedical materials, and smart materials is an urgent problem to be solved in this field. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a self-healing polyurethane elastomer, its preparation method, and its applications. The raw materials for preparing the self-healing polyurethane elastomer, by mass percentage, include: 57-67% polyether polyol, 25-30% isophthalic diisocyanate, and 7-12% dimethylglyoxime. A self-healing polyurethane elastomer material containing dynamic oxime bonds and hydrogen bonds is prepared by reacting polyether polyol, isophthalic diisocyanate, and dimethylglyoxime. The synergistic effect between these multiple bonds endows the self-healing polyurethane elastomer with high self-healing efficiency, high tensile strength, high elongation at break, high light transmittance, and resistance to yellowing, thus meeting the application requirements of self-healing polyurethane elastomers in electronic instruments, surface protection, automobiles, biomedical materials, and smart materials.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a self-healing polyurethane elastomer, wherein the raw materials for preparing the self-healing polyurethane elastomer include, by weight percentage: 57-67% polyether polyol, 25-30% isophthalic diisocyanate, and 7-12% dimethyl ethyl ketone oxime.

[0008] The isophthalimide diisocyanate (XDI) in this invention is a novel isocyanate with advantages such as high activity and fast reaction speed. XDI contains a benzene ring, and an alkyl group is introduced between the benzene ring and the isocyanate group. The alkyl group prevents resonance between the benzene ring and the isocyanate group, thus avoiding yellowing of the sample. Simultaneously, the XDI-based self-healing polyurethane elastomer possesses excellent mechanical and optical properties. This self-healing polyurethane elastomer uses dimethylglyoxime (DMG) as a chain extender, and the resulting dynamic oxime bonds can undergo exchange reactions, thereby giving the material excellent self-healing properties. The self-healing polyurethane elastomer provided by this invention is a block copolymer with polyether polyol as the soft segment and isophthalimide diisocyanate and dimethylglyoxime as the hard segment. Through the synergistic effect of dynamic oxime bonds and hydrogen bonds, it achieves high self-healing efficiency, high tensile strength, high elongation at break, high light transmittance, and resistance to yellowing.

[0009] Preferably, the mass percentage content of the polyether polyol is 57-67%, for example, it can be 57%, 60%, 65%, 67%, and specific values ​​between the above points. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0010] Preferably, the mass percentage of the isophthalamide diisocyanate is 25-30%, for example, it can be 25%, 26%, 27%, 28%, 29%, 30%, and specific values ​​between the above points. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0011] Preferably, the mass percentage of dimethylglyoxime is 7-12%, for example, it can be 7%, 8%, 9%, 10%, 11%, 12%, and specific values ​​between the above points. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0012] Preferably, the polyether polyol is polytetrahydrofuran with a number average molecular weight of 650-3000 g / mol, for example, 650 g / mol, 800 g / mol, 1000 g / mol, 1500 g / mol, 2000 g / mol, 2500 g / mol, 3000 g / mol, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific values ​​included in the range.

[0013] Preferably, the molar ratio of the polyether polyol to isophthalamide diisocyanate is 1:(2-2.8), for example, it can be 1:2, 1:2.1, 1:2.2, 1:2.3, 1:2.4, 1:2.5, 1:2.6, 1:2.7, 1:2.8, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0014] Preferably, the molar ratio of the polyether polyol to dimethylglyoxime is 1:(1-1.8), for example, it can be 1:1, 1:1.5, 1:1.8, and specific values ​​between the above points. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0015] Preferably, the raw materials used in the preparation also include a catalyst.

[0016] Preferably, the mass of the catalyst is 0.02-0.1 wt% of the total mass of the polyether polyol, isophthalamide diisocyanate, and dimethylglyoxime, for example, it can be 0.02 wt%, 0.03 wt%, 0.04 wt%, 0.05 wt%, 0.06 wt%, 0.07 wt%, 0.08 wt%, 0.09 wt%, 0.1 wt%, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0017] Preferably, the catalyst is an organotin catalyst.

[0018] Preferably, the organotin catalyst is any one or a combination of at least two of dibutyltin dilaurate, dioctyltin dilaurate, stannous octoate, or methyl thiotin.

[0019] For example, the molecular structure of the self-healing polyurethane elastomer includes structural units as shown in Formula 1:

[0020]

[0021] In a second aspect, the present invention provides a method for preparing a self-healing polyurethane elastomer as described in the first aspect, the method comprising the following steps:

[0022] (1) The polyether polyol, isophthalic diisocyanate and catalyst are mixed and reacted to obtain the prepolymer;

[0023] (2) The prepolymer obtained in step (1) is reacted with dimethylglyoxime to obtain the self-healing polyurethane elastomer.

[0024] A self-healing polyurethane elastomer was obtained by prepolymerizing polyether polyol as the soft segment with isophthalimide diisocyanate, followed by introducing dimethylglyoxime as a chain extender into the polyurethane system. This elastomer exhibits a simple preparation process, high light transmittance, excellent tensile properties, good resistance to yellowing, and highly efficient self-healing capabilities.

[0025] Preferably, the polyether polyol is dried before the reaction;

[0026] Preferably, the drying temperature is 100-120℃, for example, it can be 100℃, 105℃, 110℃, 115℃, 120℃, and specific values ​​between the above points. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0027] Preferably, the drying time is 1-3 hours, for example, it can be 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0028] Preferably, the reaction temperature in step (1) is 60-80℃, for example, it can be 60℃, 65℃, 70℃, 75℃, 80℃, and specific values ​​between the above points. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0029] Preferably, the reaction time in step (1) is 2.5-3.5h, for example, it can be 2.5h, 2.8h, 3h, 3.2h, 3.5h, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0030] Preferably, the reaction in step (1) is carried out in the presence of a solvent.

[0031] Preferably, the solvent includes N,N-dimethylformamide and / or N,N-dimethylacetamide.

[0032] Preferably, the reaction temperature in step (2) is 30-60℃, for example, it can be 30℃, 35℃, 40℃, 45℃, 50℃, 55℃, 60℃, and specific values ​​between the above points. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0033] Preferably, the reaction time in step (2) is 2-4 hours, for example, 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, this invention will not exhaustively list the specific values ​​included in the range.

[0034] Preferably, the reaction in step (2) is carried out in the presence of a solvent.

[0035] Preferably, the solvent includes N,N-dimethylformamide and / or N,N-dimethylacetamide.

[0036] Preferably, after the dimethylglyoxime in step (2) is mixed with the prepolymer obtained in step (1), a solvent is added to adjust the solid content to 20-40%, for example, 20%, 25%, 30%, 35%, 40%, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0037] Preferably, the self-healing polyurethane elastomer described in step (2) is dried in a polytetrafluoroethylene mold in a vacuum oven at 80°C.

[0038] Preferably, the reaction in step (2) is carried out under nitrogen protection.

[0039] Thirdly, the present invention provides the application of a self-healing polyurethane elastomer as described in the first aspect in electronic instruments, surface protection, automobiles, biomedical materials, and smart materials.

[0040] Compared with the prior art, the present invention has the following beneficial effects:

[0041] The raw materials for preparing the self-healing polyurethane elastomer provided by this invention include polyether polyol, isophthalamide diisocyanate, and dimethylglyoxime. Isophthalamide diisocyanate is a novel isocyanate with advantages such as high activity and fast reaction speed. The self-healing polyurethane elastomer obtained by reacting with polyether polyol and dimethylglyoxime has a light transmittance of over 90%, a tensile strength and elongation at break reaching a maximum of 34.5 MPa and 1130%, respectively, and a self-healing efficiency of tensile strength >99%. Attached Figure Description

[0042] Figure 1 This is a schematic diagram of the synthesis process of the self-healing polyurethane elastomer provided in Embodiment 1 of the present invention.

[0043] Figure 2 The stress-strain curve of the self-healing polyurethane elastomer provided in Embodiment 1 of the present invention.

[0044] Figure 3 This is a transmittance diagram of the self-healing polyurethane elastomer provided in Embodiment 1 of the present invention.

[0045] Figure 4 The image shows the yellowing resistance of the self-healing polyurethane elastomer provided in Embodiment 1 of the present invention.

[0046] Figure 5 The image shows a polarized image of scratch repair on a self-healing polyurethane elastomer provided in Embodiment 1 of the present invention (the left image is the original image, and the right image is the image after repair). Detailed Implementation

[0047] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0048] The experimental materials used in the embodiments and comparative examples of this invention are as follows:

[0049] (1) Polytetrahydrofuran 1000: P816810-500mL, Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0050] (2) m-Phenylidene diisocyanate: M158033-500g, TCI (Shanghai) Chemical Industry Development Co., Ltd.;

[0051] (3) Butylene diketone oxime: D111833-100g, Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0052] (4) 1,4-Butanediol: B110394-100g, Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0053] (5) Dibutyltin dilaurate: D100274-50g, Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0054] (6) Dioctyltin dilaurate: B830622-25g, Shanghai Maclean Biochemical Technology Co., Ltd.;

[0055] (7) N,N-Dimethylacetamide: D119664-1L, Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0056] (8) N,N-Dimethylformamide: D111999-500mL, Shanghai Aladdin Biochemical Technology Co., Ltd.

[0057] Example 1

[0058] This embodiment provides a self-healing polyurethane elastomer and its preparation method, as illustrated in the schematic diagram of the synthesis process shown below. Figure 1 As shown, the specific preparation method is as follows: 30.0g of polytetrahydrofuran (PTMEG Mn~1000) was dehydrated in a vacuum drying oven for 2 hours and then placed in a 1L round-bottom flask. 11.29g of isophthalimide diisocyanate (XDI), 10mL of N,N-dimethylacetamide (DMAc), and 0.02g of dibutyltin dilaurate (DBTDL) were added. The reaction temperature was 70℃, and the mixture was stirred for 3 hours to obtain a polyurethane prepolymer. The reaction temperature was then lowered to 40℃, and 3.48g of dimethylglyoxime (DMG) and 10mL of N,N-dimethylacetamide (DMAc) were added dropwise. The mixture was stirred for 3 hours to obtain a polyurethane elastomer. The obtained polyurethane elastomer was poured into a polytetrafluoroethylene mold and placed in a vacuum drying oven. The solvent was evaporated at 80℃ to prepare a self-healing polyurethane elastomer. Tensile strength, transmittance, yellowing resistance, and scratch repair polarization tests were performed on the elastomer, and the stress-strain curves were obtained as shown in the figure. Figure 2 As shown in the figure, the transmittance diagram is as follows: Figure 3 As shown in the diagram, the yellowing resistance is as follows: Figure 4 As shown, the polarization pattern of scratch repair is as follows: Figure 5 As shown, Figure 5 The left image is the original image, and the right image is the image after repair. It can be seen that the scratches on the sample have been completely healed.

[0059] Example 2

[0060] This embodiment provides a self-healing polyurethane elastomer and its preparation method. The only difference between this embodiment and Example 1 is the addition of 14.11g XDI, 5.23g DMG, and 0.02g DBTDL. The types, amounts, and preparation methods of other components are the same as in Example 1.

[0061] Example 3

[0062] This embodiment provides a self-healing polyurethane elastomer and its preparation method, as illustrated in the schematic diagram of the synthesis process shown below. Figure 1As shown, the specific preparation method is as follows: 30.0g of polytetrahydrofuran (PTMEG Mn~1000) was dehydrated in a vacuum drying oven for 2h and then placed in a 1L round-bottom flask. 11.29g of isophthalimide diisocyanate (XDI), 10mL of N,N-dimethylformamide (DMF), and 0.04g of dibutyltin dilaurate (DBTDL) were added. The reaction temperature was 65℃, and the mixture was stirred for 3.2h to obtain a polyurethane prepolymer. The reaction temperature was then lowered to 50℃, and 3.48g of dimethylglyoxime (DMG) and 10mL of N,N-dimethylformamide (DMF) were added dropwise. The mixture was stirred for 2.8h to obtain a polyurethane elastomer. The obtained polyurethane elastomer was poured into a polytetrafluoroethylene mold and placed in a vacuum drying oven. The solvent was evaporated at 80℃ to prepare a self-healing polyurethane elastomer.

[0063] Comparative Example 1

[0064] This comparative example provides a self-healing polyurethane elastomer and its preparation method. The only difference between this example and Example 1 is that 16.94g XDI, 6.97g DMG, and 0.02g DBTDL are used; the types, amounts, and preparation methods of other components are the same as in Example 1.

[0065] Comparative Example 2

[0066] This comparative example provides a self-healing polyurethane elastomer and its preparation method. The only difference between this example and Example 1 is that the dimethylglyoxime is replaced with 1,4-butanediol (BDO), and 30g PTMEG (Mn~1000), 11.29g XDI, 3.6g BDO, and 0.02g DBTDL are used. The types, amounts, and preparation methods of other components are the same as in Example 1.

[0067] The performance of the self-healing polyurethane elastomers provided in Examples 1-3 and Comparative Examples 1-2 was tested using the following methods:

[0068] (1) Self-healing performance test: The self-healing performance of the film samples was quantitatively studied by tensile testing. A dumbbell-shaped sample was cut in half lengthwise, and the fractured surfaces were manually brought into contact for 10 seconds. The samples were then placed in a 70℃ oven for heating and repair, without applying any external force. The tensile strength of the repaired samples was then tested again. The formula for calculating the self-healing efficiency is shown below:

[0069]

[0070] (2) Tensile strength / elongation at break: Stress-strain curves were obtained using a universal testing machine, model: CMT4104;

[0071] (3) Transmittance: The transmittance was tested by a UV-Vis spectrophotometer. The spectrum of the self-healing polyurethane elastomer sample was collected using an integrating sphere attachment. The spectral range was 400-800 nm.

[0072] (4) Yellowing test: visual inspection.

[0073] The test results are shown in Table 1:

[0074] Table 1

[0075]

[0076] As can be seen from the data in Table 1, Examples 1-2 exhibited excellent mechanical properties, with a maximum tensile strength of 34.5 MPa, a maximum elongation at break of 1130%, and a light transmittance of 91.7%. Furthermore, they did not yellow after being placed under natural light for 12 months.

[0077] The self-healing polyurethane elastomers provided in Examples 1-3 and Comparative Examples 1-2 were subjected to self-healing after fracture. The performance test results of the repaired materials are as follows:

[0078] Table 2

[0079] Tensile strength (MPa) Self-repair efficiency (%) Example 1 12.3±0.7 99.2 Example 2 34.9±0.2 101 Example 3 12.7±0.5 100 Comparative Example 1 28.6±1.6 71.5 Comparative Example 2 6.7±0.8 42.7

[0080] As can be seen from the data in Table 2, Comparative Example 1 exceeded the preferred range of the molar ratio of the raw materials, resulting in a sample with low self-healing efficiency. The molar ratio of the raw materials in Example 1 was the same as that in Comparative Example 2, and the experimental conditions were also exactly the same. The only difference was that the chain extender in Example 1 was dimethylglyoxime, while the chain extender in Comparative Example 2 was 1,4-butanediol. It can be seen that the self-healing performance of the sample in Comparative Example 2 was provided only by hydrogen bonds, with a self-healing efficiency of 42.7%. However, in Example 1, which added dimethylglyoxime, the self-healing efficiency was >99% under the synergistic effect of hydrogen bonds and oxime ester bonds.

[0081] The applicant declares that the present invention is illustrated by the above embodiments, but the present invention is not limited to the above process steps, that is, it does not mean that the present invention must rely on the above process steps to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials used in the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A self-healing polyurethane elastomer, characterized in that, The raw materials for preparing the self-healing polyurethane elastomer, by weight percentage, include: 57-67% polyether polyol, 25-30% isophthalic diisocyanate, and 7-12% dimethyl ethyl ketone oxime. The molar ratio of the polyether polyol to isophthalic diisocyanate is 1:(2-2.1). The molar ratio of the polyether polyol to dimethyl butylene oxime is 1:(1-1.5). The raw materials used in the preparation also include a catalyst; The catalyst is 0.02-0.1 wt% of the total mass of polyether polyol, isophthalic diisocyanate and dimethylglyoxime.

2. The self-healing polyurethane elastomer according to claim 1, characterized in that, The polyether polyol includes polytetrahydrofuran.

3. The self-healing polyurethane elastomer according to claim 2, characterized in that, The number-average molecular weight of the polytetrahydrofuran is 650-3000 g / mol.

4. The self-healing polyurethane elastomer according to claim 1, characterized in that, The catalyst is an organotin catalyst.

5. The self-healing polyurethane elastomer according to claim 4, characterized in that, The organotin catalyst is any one or a combination of at least two of dibutyltin dilaurate, dioctyltin dilaurate, stannous octoate, or methyl thiotin.

6. A method for preparing a self-healing polyurethane elastomer as described in any one of claims 1-5, characterized in that, The preparation method includes the following steps: (1) The polyether polyol, isophthalic diisocyanate and catalyst are mixed and reacted to obtain the prepolymer; (2) The prepolymer obtained in step (1) is reacted with dimethylglyoxime to obtain the self-healing polyurethane elastomer.

7. The preparation method according to claim 6, characterized in that, The polyether polyol is dried before being reacted.

8. The preparation method according to claim 7, characterized in that, The drying temperature is 100-120 °C.

9. The preparation method according to claim 7, characterized in that, The drying time is 1-3 hours.

10. The preparation method according to claim 6, characterized in that, The reaction temperature in step (1) is 60-80 °C.

11. The preparation method according to claim 6, characterized in that, The reaction time in step (1) is 2.5-3.5 h.

12. The preparation method according to claim 6, characterized in that, The reaction described in step (1) is carried out in the presence of a solvent.

13. The preparation method according to claim 12, characterized in that, The solvent includes N,N-dimethylformamide and / or N,N-dimethylacetamide.

14. The preparation method according to claim 6, characterized in that, The reaction temperature in step (2) is 30-60℃.

15. The preparation method according to claim 6, characterized in that, The reaction time in step (2) is 2-4 h.

16. The preparation method according to claim 6, characterized in that, The reaction described in step (2) is carried out in the presence of a solvent.

17. The preparation method according to claim 16, characterized in that, The solvent includes N,N-dimethylformamide and / or N,N-dimethylacetamide.

18. The application of a self-healing polyurethane elastomer as described in any one of claims 1-5 in electronic instruments, surface protection, automobiles, biomedical materials, and smart materials.

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