Solvent-resistant anti-aging low-temperature polyurethane elastomer as well as preparation method and application thereof

Abstract

The invention provides a solvent-resistant anti-aging low-temperature polyurethane elastomer as well as a preparation method and application thereof, and relates to the field of materials. The structural formula of the solvent-resistant anti-aging low-temperature polyurethane elastomer is # imgabs0 #. The low-temperature polyurethane elastomer has good low-temperature resistance, aging resistance and solvent resistance at the same time.

Description

Technical Field

[0001] The present application relates to the field of materials, and particularly to a low-temperature polyurethane elastomer with solvent resistance and anti-aging properties, and a preparation method and use thereof. Background Art

[0002] Traditional elastomeric materials, such as rubber, are widely used in sealing devices, tires, brakes, and medical devices, etc. due to their good elasticity and mechanical properties. However, due to some significant disadvantages such as aging, low-temperature crystallization, and solvent intolerance, etc., it greatly limits its practical application and service life in some extreme environments.

[0003] Currently, in order to meet extreme applications such as extreme low temperature (less than -80 °C), solvents, and aging, the preparation of related elastomeric materials mainly involves strategies such as synthesis and modification, for example, polycarbonate, silicone rubber, introducing antifreeze solvents, etc. For improving the solvent resistance of materials, methods such as increasing the crosslinking density and phase separation strategies are often used to improve the solvent resistance of materials, and at the same time, introducing some antifreeze small molecules such as ionic liquids and glycerol and other solvents or introducing polymers with low glass transition temperature for blending. For the improvement of anti-aging performance, currently, commercially available amine or hindered phenol antioxidants, fillers or small molecules are often introduced. Inevitably, the introduction of additional systems has a huge impact on the material uniformity, and small molecules are extremely prone to agglomeration and migration during long-term use, which affects the service life and safety of materials. Currently, a suitable approach is to develop materials that are inherently solvent-resistant and anti-aging. At the same time, for many elastomeric materials such as natural rubber and polyurethane and other conventional commercial materials, their glass transition temperatures are difficult to meet the requirements of extreme low temperature. When the temperature is below -80 °C, these materials will become brittle and lack flexibility, so that the materials will be quickly scrapped. For example, natural rubber has a glass transition temperature of -60 °C, which will be difficult to meet the special requirements of extreme low temperature conditions such as extremely low scientific research and aerospace.

[0004] Although the low temperature of the material can be significantly improved by introducing low-temperature segments such as silicone rubber. However, due to the lack of low-temperature flexibility, solvent resistance, and aging resistance, the preparation process is relatively cumbersome, and the prepared elastomeric materials are often not ideal, and it is difficult to simultaneously take into account the properties of low-temperature resistance, solvent resistance, and aging resistance. Summary of the Invention

[0005] The purpose of the present application is to provide a low-temperature polyurethane elastomer with solvent resistance and anti-aging properties, and a preparation method and use thereof, so as to solve the above problems.

[0006] To achieve the above purpose, the present application adopts the following technical solutions:

[0007] A low-temperature polyurethane elastomer with solvent resistance and anti-aging properties, the general structural formula thereof is as follows:

[0008]

[0009] Among them, R' is

[0010]

[0011] -NH 2 one or more of; m, n, and x are positive integers.

[0012] Preferably, the Mw of the solvent-resistant and anti-aging low-temperature polyurethane elastomer is not higher than 100,000.

[0013] This application also provides a preparation method of the solvent-resistant and anti-aging low-temperature polyurethane elastomer described above, including:

[0014] Performing a condensation reaction on 2,4,6-triaminopyrimidine and protocatechuic aldehyde to obtain Schiff base TPA;

[0015] Mixing perfluoropolyether diol, hexamethylene diisocyanate, and a catalyst and performing condensation polymerization to obtain a precursor solution;

[0016] Performing a heating reaction on the Schiff base TPA and the precursor solution to obtain the solvent-resistant and anti-aging low-temperature polyurethane elastomer.

[0017] Preferably, the preparation method of the solvent-resistant and anti-aging low-temperature polyurethane elastomer satisfies one or more of the following conditions:

[0018] A. The mass ratio of the 2,4,6-triaminopyrimidine to the protocatechuic aldehyde is 1:(1 - 3.4);

[0019] B. The system solvent for the condensation reaction is a mixture of methanol and N,N-dimethylformamide and / or N,N-dimethylacetamide, and the amount of methanol used is 20% - 50% of the volume of N,N-dimethylformamide and / or N,N-dimethylacetamide;

[0020] C. The temperature of the condensation reaction is 50 - 80°C, and the time is 12 - 48 h;

[0021] D. After the condensation reaction is completed, it further includes: precipitating and removing impurities from the reaction product using ethanol.

[0022] Preferably, the preparation method of the solvent-resistant and anti-aging low-temperature polyurethane elastomer satisfies one or more of the following conditions:

[0023] (1) The structural formula of the perfluoropolyether diol is

[0024] (2) The molecular weight Mw of the perfluoropolyether diol is 500 - 2000;

[0025] (3) The mass ratio of the perfluoropolyether diol, the hexamethylene diisocyanate and the Schiff base TPA is 1:(2 - 2.4):(0.5 - 1).

[0026] Preferably, the catalyst includes dibutyltin dilaurate.

[0027] Preferably, the temperature of the polycondensation polymerization is 50 - 80 °C and the time is 4 - 24 h.

[0028] Preferably, the temperature of the heating reaction is 40 - 70 °C and the time is 12 - 24 h.

[0029] Preferably, after the heating reaction, it further includes: allowing the reaction product to stand and settle, and then washing with N,N - dimethylformamide to obtain the solvent - resistant and anti - aging low - temperature polyurethane elastomer.

[0030] This application also provides a use of the solvent - resistant and anti - aging low - temperature polyurethane elastomer described above, which is used for sealing devices, tires, brakes and medical devices.

[0031] Compared with the prior art, the beneficial effects of this application include:

[0032] The solvent - resistant and anti - aging low - temperature polyurethane elastomer provided by this application is a perfluoropolyether - based polyurethane elastomer material containing a catechol structure. Due to the introduction of the catechol structure, the free radicals generated during the aging process of the material can be quickly and effectively captured and inactivated by the catechol groups, preventing the further evolution of the aging process, which makes the material have strong anti - aging performance. In addition, since the main body of the polyurethane soft segment is a perfluoropolyether structure, this makes the molecular chains of the material have strong intermolecular forces and good flexibility at low temperatures, which can well improve the low - temperature resistance and solvent resistance of the material, enabling it to perform tensile tests at - 80 °C and - 100 °C and be able to cycle deformation, and still have flexibility even under liquid nitrogen conditions, and show excellent swelling resistance to solvents with different polarities such as tetrahydrofuran, DMF, and petroleum ether.

[0033] The preparation method of the solvent - resistant and anti - aging low - temperature polyurethane elastomer provided by this application is simple and convenient to operate, and the reaction conditions are mild.

[0034] The solvent - resistant and anti - aging low - temperature polyurethane elastomer provided by this application has a wide range of uses. Description of the Drawings

[0035] To more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the accompanying drawings required for the embodiments. It should be understood that the following drawings only show some embodiments of the present application and should not be regarded as limiting the scope of the present application.

[0036] Figure 1 Photos of raw materials TAP and PA used in the examples and the resulting Schiff base TPA;

[0037] Figure 2 Photo of the elastomer obtained in Example 1;

[0038] Figure 3 Bar chart of the solvent resistance test results of the elastomers of Example 1 and Comparative Example 1;

[0039] Figure 4 Bar chart of the stress-strain retention rate of the polyurethane elastomer prepared in Example 1 before and after aging;

[0040] Figure 5 Bar chart of the stress-strain retention rate of the polyurethane elastomer prepared in Comparative Example 2 before and after aging;

[0041] Figure 6 Comparison photos of the elastomers of Example 1 and Comparative Example 2 before and after aging;

[0042] Figure 7 Comparison photos of the low-temperature resistance performance of the PFTA polyurethane elastomer prepared in Example 1 and other commercial polyurethane elastomers in liquid nitrogen. Detailed implementation manners

[0043] To better explain the technical solutions provided by the present application, before the examples, the technical solutions will be presented as a whole as follows:

[0044] A solvent-resistant and anti-aging low-temperature polyurethane elastomer has the following general structural formula:

[0045]

[0046] Among them, R' is

[0047]

[0048] -NH 2 One or more of them; m, n, and x are positive integers.

[0049] In an optional implementation manner, the Mw of the solvent-resistant and anti-aging low-temperature polyurethane elastomer is not higher than 100,000.

[0050] The present application also provides a preparation method of the solvent-resistant and anti-aging low-temperature polyurethane elastomer, including:

[0051] The condensation reaction of 2,4,6-triaminopyrimidine and protocatechualdehyde yields the Schiff base TPA;

[0052] The perfluoropolyether diol, hexamethylene diisocyanate and a catalyst are mixed for condensation polymerization to obtain a precursor solution;

[0053] The Schiff base TPA and the precursor solution are subjected to a heating reaction to obtain the solvent-resistant and anti-aging low-temperature polyurethane elastomer.

[0054] The reaction equations of the above reactions are as follows:

[0055]

[0056] The resulting product is TPA, where R is -NH 2 and / or

[0057] The resulting product is PF-NCO.

[0058] Finally, TPA reacts with PF-NCO to obtain the target material.

[0059] In an alternative embodiment, the method for preparing the solvent-resistant and anti-aging low-temperature polyurethane elastomer satisfies one or more of the following conditions:

[0060] A. The mass ratio of the 2,4,6-triaminopyrimidine to the protocatechualdehyde is 1:(1 - 3.4);

[0061] Optionally, the mass ratio of the 2,4,6-triaminopyrimidine to the protocatechualdehyde can be 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.4 or any value between 1:(1 - 3.4);

[0062] B. The system solvent for the condensation reaction is a mixture of methanol and N,N-dimethylformamide and / or N,N-dimethylacetamide, and the amount of methanol used is 20% - 50% of the volume of N,N-dimethylformamide and / or N,N-dimethylacetamide;

[0063] Optionally, the amount of methanol used can be 20%, 30%, 40%, 50% or any value between 20% - 50% of the volume of N,N-dimethylformamide and / or N,N-dimethylacetamide;

[0064] C. The temperature of the condensation reaction is 50 - 80 °C and the time is 12 - 48 h;

[0065] Optionally, the temperature of the condensation reaction can be 50 °C, 60 °C, 70 °C, 80 °C or any value between 50 - 80 °C, and the time can be 12 h, 16 h, 20 h, 24 h, 28 h, 32 h, 36 h, 40 h, 44 h, 48 h or any value between 12 - 48 h;

[0066] D. After the condensation reaction, it further includes: precipitating and removing impurities from the reaction product with ethanol.

[0067] In an optional embodiment, the preparation method of the solvent-resistant anti-aging low-temperature polyurethane elastomer satisfies one or more of the following conditions:

[0068] (1) The structural formula of the perfluoropolyether diol is

[0069] (2) The molecular weight of the perfluoropolyether diol is 500 - 2000;

[0070] (3) The mass ratio of the perfluoropolyether diol, the hexamethylene diisocyanate and the Schiff base TPA is 1:(2 - 2.4):(0.5 - 1).

[0071] Optionally, the mass ratio of the perfluoropolyether diol, the hexamethylene diisocyanate and the Schiff base TPA can be 1:2:0.5, 1:2.2:0.8, 1:2.4:1 or any value between 1:(2 - 2.4):(0.5 - 1).

[0072] In an optional embodiment, the catalyst includes dibutyltin dilaurate.

[0073] In an optional embodiment, the temperature of the condensation polymerization is 50 - 80 °C and the time is 4 - 24 h.

[0074] Optionally, the temperature of the condensation polymerization can be 50 °C, 60 °C, 70 °C, 80 °C or any value between 50 - 80 °C, and the time can be 4 h, 8 h, 12 h, 16 h, 20 h, 24 h or any value between 4 - 24 h.

[0075] In an optional embodiment, the temperature of the heating reaction is 40 - 70 °C and the time is 12 - 24 h.

[0076] Optionally, the temperature of the heating reaction can be 40 °C, 50 °C, 60 °C, 70 °C or any value between 40 - 70 °C, and the time can be 12 h, 16 h, 20 h, 24 h or any value between 12 - 24 h.

[0077] In an alternative embodiment, after the heating reaction is completed, the method further includes: allowing the reaction product to stand and settle, and then washing with N,N-dimethylformamide to obtain the solvent-resistant and anti-aging low-temperature polyurethane elastomer.

[0078] The present application also provides a use of the solvent-resistant and anti-aging low-temperature polyurethane elastomer, which is used for sealing devices, tires, brakes, and medical devices.

[0079] The following will describe the embodiments of the present application in detail with reference to specific examples. However, those skilled in the art will understand that the following examples are only for illustrating the present application and should not be construed as limiting the scope of the present application. For those conditions not specified in the examples, they are carried out according to conventional conditions or conditions recommended by the manufacturer. For reagents or instruments without indicating the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0080] Example 1

[0081] This example provides a solvent-resistant and anti-aging low-temperature polyurethane elastomer, and its preparation method is as follows:

[0082] (1) Accurately weigh 7.6 g of 2,4,6-triaminopyrimidine and 17 g of protocatechuic aldehyde and dissolve them in a mixed solvent containing 100 ml of DMF and 50 ml of methanol. After reacting in an oil bath at 70 °C for 24 hours, add a sufficient amount of ethanol to precipitate and remove impurities to obtain a solid Schiff base material.

[0083] (2) Accurately weigh 12 g of perfluoropolyether diol with a molecular weight of Mw = 905 after drying and removing water, 0.1 g of dibutyltin dilaurate, and 4.3 g of hexamethylene diisocyanate, and mix them. React in an oil bath at 70 °C for 24 hours. Then, dissolve 1.5 g of the above-obtained Schiff base in 150 ml of DMF solvent, filter it through a filter membrane (pore size 0.2 - 0.4 μm), and inject it into the above reaction vessel to continue reacting at 40 °C for 24 h. Finally, allow it to stand and precipitate solid insoluble substances, wash with a sufficient amount of DMF to remove impurities, and dry at 70 °C. The aging methods are: thermal-oxidative aging and ultraviolet aging. Among them, thermal-oxidative aging is to place the sample in a thermal-oxidative aging test chamber at 100 °C, and ultraviolet aging is tested using an ultraviolet light aging test chamber with a wavelength of 340 nm.

[0084] The photos of the raw materials TAP and PA and the obtained Schiff base TPA are as Figure 1 shown. The photo of the obtained elastomer is as Figure 2 shown.

[0085] Measure its mechanical properties and glass transition temperature, and the results are shown in Table 1:

[0086] Table 1. Test results of the elastomer prepared in Example 1

[0087]

[0088] The carbon and oxygen contents of the elastomer obtained in Example 1 before and after aging were measured, and the results are shown in Table 2:

[0089] Table 2 Comparison of carbon and oxygen contents of the elastomer in Example 1 before and after aging

[0090] O / C ratio before aging, % O / C content after thermal-oxidative aging, % O / C content after UV aging, % 84.81±3.20 85.78±2.47 78.33±1.63

[0091] Example 2

[0092] This example provides a solvent-resistant and anti-aging low-temperature polyurethane elastomer, and its preparation method is as follows:

[0093] (1) Accurately weigh 7.6 g of 2,4,6-triaminopyrimidine and 20 g of protocatechuic aldehyde and dissolve them in a mixed solvent containing 100 ml of DMF and 50 ml of methanol. After reacting in an oil bath at 50 °C for 24 hours, add sufficient ethanol to precipitate and remove impurities to obtain a solid Schiff base material.

[0094] (2) Different from Example 1, in Example 2, the addition amount of isocyanate was changed. Accurately weigh 12 g of perfluoropolyether diol with a molecular weight of 905 after drying and removing water, 0.1 g of dibutyltin dilaurate, and 5.375 g (1.25 times that of Example 1) or 6.45 g (1.5 times that of Example 1) of hexamethylene diisocyanate and mix them. React in an oil bath at 60 °C for 24 hours. Then, dissolve 1.5 g of the above-obtained Schiff base in 150 ml of DMF solvent, filter it through a filter membrane, inject it into the above reaction vessel, and continue to react at 40 °C for 24 h. Finally, let it stand to precipitate solid insoluble substances, wash and remove impurities with sufficient DMF, and dry at 70 °C.

[0095] The performance data of the elastomer prepared in Example 2 are shown in Table 3:

[0096] Table 3 Performance of the elastomer prepared in Example 2

[0097]

[0098] Example 3

[0099] This example provides a solvent-resistant and anti-aging low-temperature polyurethane elastomer, and its preparation method is as follows:

[0100] Step (1) is the same as that in Example 1;

[0101] (2) Weigh accurately 12 g of perfluoropolyether diol with a molecular weight of 1500 after drying and removing water, 0.1 g of dibutyltin dilaurate, and 4.3 g of hexamethylene diisocyanate, mix them, and react in an oil bath at 70 °C for 24 hours. Then, dissolve 1.5 g of the Schiff base obtained above in 150 ml of DMF solvent, filter it through a filter membrane, and inject it into the above reaction vessel to continue the reaction at 40 °C for 24 h. Finally, let it stand to precipitate solid insoluble substances, wash them with sufficient DMF to remove impurities, and dry them at 70 °C.

[0102] The performance data of the elastomer prepared in Example 3 are shown in Table 4:

[0103] Table 4 Performance data

[0104]

[0105] With the increase in the molecular weight of the perfluoropolyether raw material, its tensile strength and tensile strain also increase. Due to the increase in the main-chain fluorine content of the molecular chain, its glass transition temperature further decreases.

[0106] Comparative Example 1

[0107] Taking the existing common elastomer as a control, the solvent resistance of the materials in Example 1 and Comparative Example 1 was tested. Take 0.1 g of the sample, place it in 10 ml of the solvent, soak it for 24 h to fully swell, and the results are as Figure 3 shown.

[0108] The perfluoropolyether elastomer prepared in this application exhibits good low-temperature resistance, its glass transition temperature can be as low as -115 °C, and after high-temperature thermal oxygen and ultraviolet aging, no obvious changes in the mechanical properties of the material are observed, and the surface morphology is discoloration and cracking, showing good anti-aging performance. With the increase in the isocyanate in the system, the tensile strength of the material increases, but the strain and glass transition temperature performance weaken. From the swelling rate, the prepared elastomer has good swelling resistance and far exceeds the commercial natural rubber and VHB elastomer.

[0109] Comparative Example 2

[0110] Weigh accurately 12 g of perfluoropolyether diol with a molecular weight of 905 after drying and removing water, 0.1 g of dibutyltin dilaurate, and 4.3 g of hexamethylene diisocyanate, mix them, and react in an oil bath at 70 °C for 24 hours. Then add butanediol with the same molar ratio as the perfluoropolyether as a chain extender, dissolve it in 150 ml of DMF solution, continue the reaction at 40 °C for 24 h, and then dry it at 70 °C. Compare the anti-aging performance of the perfluoropolyether elastomer without catechol structure.

[0111] The stress-strain retention rate of the polyurethane elastomer prepared in Example 1 before and after aging is as Figure 4 shown.

[0112] The stress-strain retention rates of the polyurethane elastomer prepared in Comparative Example 2 before and after aging are as Figure 5 shown.

[0113] The photos of the elastomers obtained in Example 1 (PFTA) and Comparative Example 2 before and after aging are as Figure 6 shown.

[0114] Compared with the perfluoropolyether-based elastomer without catechol structure, after thermal-oxidative and ultraviolet aging, the aging phenomenon of the material is obvious, the material turns yellow and the surface morphology cracks. And in Comparative Example 2, without the protection of the anti-aging effect of the catechol matrix, the stress-strain properties of the material are greatly weakened.

[0115] Comparative Example 3

[0116] Commercially available natural rubber, silicone rubber, commercially available polyurethane elastomer and ethyl acrylate elastomer were selected to conduct flexibility tests with the synthesized Example 1 under liquid nitrogen conditions.

[0117] The comparison photos of the low-temperature resistance of the PFTA polyurethane elastomer prepared in Example 1 and other commercially available polyurethane elastomers are as Figure 7 shown.

[0118] Compared with a variety of commercially available elastic materials, the elastomer material prepared in this application has good low-temperature resistance. Even under liquid nitrogen temperature conditions, the prepared polyurethane elastomer still retains flexibility and can perform various action operations.

[0119] It should be noted that the above-mentioned mechanical, anti-freezing, solvent-resistant, anti-aging and aging test equipment includes: stretching with a universal testing machine equipped with an environmental chamber at a rate of 2 mm / min, and using a thermal-oxidative aging machine at 100 °C and an ultraviolet aging instrument to conduct aging experiments on the material, and using an elemental analyzer to test the change of carbon and oxygen content.

[0120] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A solvent-resistant and anti-aging low-temperature polyurethane elastomer, characterized in that: Its general structure is as follows: Among them, R' is -NH2; m, n, x are positive integers.

2. The solvent-resistant and aging-resistant low-temperature polyurethane elastomer according to claim 1, characterized in that: The Mw of the solvent-resistant and aging-resistant low-temperature polyurethane elastomer is not higher than 100,000.

3. A method for preparing the solvent-resistant and aging-resistant low-temperature polyurethane elastomer according to claim 1 or 2, characterized in that: include: 2,4,6-triaminopyrimidine and protocatechuic aldehyde are subjected to condensation reaction to obtain Schiff base TPA; The perfluoropolyether diol, hexamethylene diisocyanate and a catalyst are mixed and subjected to condensation polymerization to obtain a precursor solution; The Schiff base TPA is heated and reacted with the precursor solution to obtain the solvent-resistant and aging-resistant low-temperature polyurethane elastomer.

4. The method for preparing the solvent-resistant and aging-resistant low-temperature polyurethane elastomer according to claim 3, characterized in that: One or more of the following conditions are met: A. The mass ratio of the 2,4,6-triaminopyrimidine to the protocatechuic aldehyde is 1:(1-3.4); B. The system solvent of the condensation reaction is a mixture of methanol and N'N-dimethylformamide and / or N'N-dimethylacetamide, and the amount of methanol is 20%-50% of the volume of N'N-dimethylformamide and / or N'N-dimethylacetamide; C. The condensation reaction temperature is 50-80°C and the time is 12-48h; D. After the condensation reaction is completed, the method further comprises: using ethanol to precipitate and remove impurities from the reaction product.

5. The method for preparing the solvent-resistant and aging-resistant low-temperature polyurethane elastomer according to claim 3, characterized in that: One or more of the following conditions are met: (1) The structural formula of the perfluoropolyether diol is (2) The Mw of the perfluoropolyether diol is 500-2000; (3) The mass ratio of the perfluoropolyether diol, the hexamethylene diisocyanate and the Schiff base TPA is 1:(2-2.4):(0.5-1).

6. The method for preparing the solvent-resistant and aging-resistant low-temperature polyurethane elastomer according to claim 3, characterized in that: The catalyst includes dibutyltin dilaurate.

7. The method for preparing the solvent-resistant and aging-resistant low-temperature polyurethane elastomer according to claim 3, characterized in that: The temperature of the condensation polymerization is 50-80° C. and the time is 4-24 hours.

8. The method for preparing the solvent-resistant and aging-resistant low-temperature polyurethane elastomer according to claim 3, characterized in that: The heating reaction is carried out at a temperature of 40-70°C and for a time of 12-24 hours.

9. The method for preparing a solvent-resistant and aging-resistant low-temperature polyurethane elastomer according to any one of claims 3 to 8, characterized in that: After the heating reaction is completed, the further step includes: allowing the reaction product to settle, and then washing it with N'N-dimethylformamide to obtain the solvent-resistant and aging-resistant low-temperature polyurethane elastomer.

10. Use of the solvent-resistant and aging-resistant low-temperature polyurethane elastomer according to claim 1 or 2, characterized in that: Used in seals, tires, brakes and medical devices.

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