High-temperature-resistant polyurethane elastomer and preparation method thereof

Abstract

The invention discloses a high-temperature-resistant polyurethane elastomer and a preparation method thereof, and relates to the technical field of polymer materials, the high-temperature-resistant polyurethane elastomer comprises the following specific components: polyether polyol, poly (toluene diisocynate) pMD I, a chain extender and a cross-linking agent; the high-temperature-resistant polyurethane elastomer further comprises additives, wherein the additives specifically comprise nano aluminum silicate fibers, a titanium phosphate-based temperature-resistant synergist, a multi-walled carbon nanotube grafted amide group and a metal organic framework composite material. According to the high-temperature-resistant polyurethane elastomer and the preparation method thereof, multiple additives and nano aluminum silicate fibers are introduced into the polyurethane elastomer, so that the thermal isolation property of the material is effectively improved; the multi-walled carbon nanotube grafted amide group improves the thermal conductivity, and solves the problem of poor dispersibility of the carbon nanotube in a polyurethane matrix; the thermal stability of the material is further improved by the titanium phosphate-based temperature-resistant synergist; the introduction of the metal organic framework composite material significantly improves the gas isolation and thermal stability of the material.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, and specifically provides a high-temperature resistant polyurethane elastomer and a preparation method thereof. Background Art

[0002] Due to its excellent mechanical properties, elastic recovery and wear resistance, polyurethane elastomers have been widely used in industries, transportation, aerospace and other fields. However, traditional polyurethane elastomers are prone to problems such as thermal-oxidative aging, molecular chain breakage and mechanical property degradation under high-temperature environments, which severely limit their applications in high-temperature environments. Therefore, improving the high-temperature resistance and thermal stability of polyurethane elastomers has become an important research direction.

[0003] In the prior art, common high-temperature resistant polyurethane elastomers usually enhance their thermal stability by introducing heat-resistant polyether polyols, aromatic isocyanates, chain extenders and crosslinking agents. However, these conventional methods still have the following deficiencies in practical applications:

[0004] Insufficient thermal stability: The performance of traditional polyurethane elastomers significantly decreases at high temperatures (such as above 180°C), and the molecular chain segments undergo thermal-oxidative degradation, resulting in reduced toughness of the material, loss of elasticity, and seriously affecting the service life.

[0005] Decrease in mechanical strength: Although some additives (such as glass fiber and carbon fiber) can enhance the mechanical properties to a certain extent, they cannot maintain their structural integrity and strength at high temperatures, resulting in cracking or delamination of the material under stress.

[0006] Poor thermal conductivity: Due to the low thermal conductivity of the polyurethane matrix material itself, local heat accumulation is likely to occur in high-temperature applications, thereby causing thermal damage and aging phenomena. The prior art lacks effective measures to improve the thermal conductivity, especially showing obvious deficiencies in dealing with dynamic high-temperature environments.

[0007] Poor material dispersion: Traditional fillers (such as carbon nanotubes, glass fibers, etc.) have poor dispersion in the matrix, resulting in an insignificant enhancement effect and even a reduction in material properties due to uneven dispersion. Summary of the Invention

[0008] Aiming at the deficiencies of the prior art, the present invention provides a high-temperature resistant polyurethane elastomer and a preparation method thereof to solve the problems raised in the above background art.

[0009] To achieve the above object, the present invention provides the following technical solutions:

[0010] The embodiment of the present invention provides a high-temperature resistant polyurethane elastomer, which includes the following specific components: polyether polyol, polymethylene polyphenyl isocyanate pMDI, chain extender, crosslinking agent;

[0011] The parts by mass of the above components are as follows:

[0012] The polyether polyol is 70 - 80 parts;

[0013] The pMDI is 20 - 25 parts;

[0014] The chain extender is 5 - 10 parts;

[0015] The crosslinking agent is 1 - 3 parts;

[0016] The high - temperature resistant polyurethane elastomer further includes additives, and the additives specifically include nano - aluminum silicate fiber, titanium phosphate - based temperature - resistant synergist, multi - walled carbon nanotube grafted amide group, and metal - organic framework composite material;

[0017] The nano - aluminum silicate fiber is 2 - 5 parts;

[0018] The titanium phosphate - based temperature - resistant synergist is 1 - 3 parts;

[0019] The multi - walled carbon nanotube grafted amide group is 0.5 - 2 parts;

[0020] The metal - organic framework composite material is 3 - 6 parts.

[0021] To further optimize this technical solution, in the specific composition components:

[0022] The polyether polyol is selected from high - molecular - weight polyether diol or modified polyether triol;

[0023] The pMDI is selected from polyphenylene polymethyl polyisocyanate;

[0024] The chain extender is selected from 1,4 - butanediol (BDO), diethylene glycol (DEG) or 1,6 - hexanediol (HDO);

[0025] The crosslinking agent is selected from trimethylolpropane (TMP).

[0026] To further optimize this technical solution, among the additives, the fiber diameter of the nano - aluminum silicate fiber is 20 - 50 nm, the length is 1 - 5 μm, and surface chemical activation treatment is carried out using a surface activator;

[0027] The surface activator is a coupling agent containing an organosilicon group, including γ - aminopropyltriethoxysilane (KH - 550), which is used to improve the dispersibility and compatibility of the nano - aluminum silicate fiber in the polyurethane elastomer.

[0028] To further optimize this technical solution, among the additives, the titanium phosphate - based temperature - resistant synergist includes titanium phosphate (TiP2O7) and nano - titanate (TiO3) 2- ;

[0029] Titanium phosphate is used to form a titanate protective layer at high temperatures, effectively blocking the oxidation degradation reaction;

[0030] Nanometer titanate forms a dense interfacial layer in the polyurethane elastomer through adsorption and complexation. The nanometer titanate is prepared by the sol-gel method, and its particle size is 50 - 100 nm.

[0031] To further optimize this technical solution, among the additives, the multi-walled carbon nanotubes grafted with amide groups include multi-walled carbon nanotubes MWCNTs and grafted groups;

[0032] The diameter of the multi-walled carbon nanotubes is 20 - 30 nm, and the length is 2 - 10 μm;

[0033] The grafted group is the amide group -CONH2, and grafting modification is carried out after acidification treatment.

[0034] To further optimize this technical solution, among the additives, the metal-organic framework composite material includes titanium-organic framework Ti-MOF and modified groups;

[0035] The titanium-organic framework forms a microporous structure in the polyurethane elastomer through the molecular sieve effect;

[0036] The modified group is the carboxylic acid group -COOH, which is used to enhance the interfacial compatibility.

[0037] A preparation method of a high-temperature resistant polyurethane elastomer is based on the above-mentioned high-temperature resistant polyurethane elastomer and includes the following specific steps:

[0038] S1. Prepare a polyurethane prepolymer;

[0039] Mix polyether polyol and pMDI according to the mass fraction, put them into a reaction kettle, control the temperature at 90 °C, and react for 2 hours to obtain a polyurethane prepolymer;

[0040] S2. Introduce nanoaluminum silicate fiber;

[0041] Add nanoaluminum silicate fiber to the polyurethane prepolymer obtained in step S1, and use a high-shear stirrer to stir to ensure the uniform dispersion of the nanoaluminum silicate fiber and the polyurethane matrix;

[0042] S3. Add a chain extender;

[0043] Add a chain extender to the polyurethane prepolymer in step S2. The chain extender reacts with the unreacted isocyanate groups in the polyurethane, and the reaction is carried out at 80 °C for 1 hour;

[0044] S4. Form a preliminary polyurethane elastomer;

[0045] Transfer the polyurethane prepolymer obtained from the reaction in step S3 to a reaction mold, and perform hot pressing on it. The mold temperature is set at 100 °C, the pressure is 5 MPa, and the reaction time is 2 hours to preliminarily shape the polyurethane elastomer.

[0046] S5. Introduce a crosslinking agent;

[0047] Add a crosslinking agent to the preliminary polyurethane elastomer, set the reaction temperature at 90 °C, and the reaction time at 1 hour;

[0048] S6. Add multi-walled carbon nanotubes grafted with amide groups;

[0049] Add multi-walled carbon nanotubes grafted with amide groups to the polyurethane elastomer obtained in step S5, and use a high-shear stirrer for uniform dispersion. Control the stirring temperature at 80 °C and the stirring time at 30 minutes;

[0050] S7. Add a titanium phosphate-based temperature-resistant synergist;

[0051] Add a titanium phosphate-based temperature-resistant synergist to the polyurethane elastomer obtained in step S6, control the reaction temperature at 100 °C, and the reaction time at 1 hour;

[0052] S8. Introduce a metal-organic framework composite material;

[0053] Add the metal-organic framework composite material to the polyurethane elastomer obtained in step S7, and perform high-efficiency stirring. After stirring is completed, cure it to obtain the final high-temperature-resistant polyurethane elastomer.

[0054] Further optimize this technical solution. In step S2, the particle size of the nano-aluminum silicate fiber is controlled below 50 nm. When using a high-shear stirrer for mixing, set the stirring temperature at 70 °C and continuously stir for 30 minutes.

[0055] Further optimize this technical solution. In step S6, the steps for grafting amide groups onto multi-walled carbon nanotubes are as follows:

[0056] Dissolve the multi-walled carbon nanotubes in an N,N-dimethylacetamide solvent, and add an amination reagent to the solution for amidation reaction;

[0057] Under nitrogen protection, control the reaction temperature at 60 °C and the reaction time at 3 hours to ensure that the amide groups fully react with the surface of the multi-walled carbon nanotubes and the grafting amount reaches the required level.

[0058] Further optimize this technical solution. In step S8, the amount of the metal-organic framework composite material added is controlled at 1-5 wt%, and use a high-shear stirrer to uniformly mix the metal-organic framework composite material with the polyurethane elastomer. Control the stirring temperature at 60 °C and the stirring time at 30 minutes.

[0059] Compared with the prior art, the present invention provides a high-temperature resistant polyurethane elastomer and a preparation method thereof, having the following beneficial effects:

[0060] In the high-temperature resistant polyurethane elastomer and the preparation method thereof, by introducing various additives into the polyurethane elastomer, the high-temperature resistance, mechanical strength and thermal conductivity of the material are significantly improved. Among them, nano-aluminum silicate fiber effectively improves the thermal insulation of the material and enhances the structural stability at high temperatures; grafting amide groups on multi-walled carbon nanotubes solves the problem of poor dispersion of carbon nanotubes in the polyurethane matrix while improving the thermal conductivity; titanium phosphate-based temperature-resistant synergist further improves the thermal stability of the material; the introduction of metal-organic framework composite materials significantly improves the gas barrier property and thermal stability of the material, and exhibits excellent mechanical properties and long-lasting high-temperature resistance in a dynamic high-temperature environment. The present invention overcomes the deficiencies of traditional high-temperature resistant polyurethane elastomers in terms of thermal stability, mechanical strength, thermal conductivity and dispersion uniformity, significantly expands the application scope of polyurethane elastomers in high-temperature industrial environments, and has good promotion value and broad market prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained according to these drawings.

[0062] Figure 1 It is a schematic diagram of the components of a high-temperature resistant polyurethane elastomer proposed by the present invention;

[0063] Figure 2 It is a schematic flow chart of a preparation method of a high-temperature resistant polyurethane elastomer proposed by the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0064] In order to make the above objects, features and advantages of the present invention more obvious and understandable, the following will make a detailed description of the specific embodiments of the present invention with reference to the drawings in the specification.

[0065] In the following description, many specific details are set forth in order to fully understand the present invention. However, the present invention can also be implemented in other ways different from those described herein. Those skilled in the art can make similar promotions without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0066] Secondly, the "one embodiment" or "embodiment" mentioned herein refers to specific features, structures or characteristics that may be included in at least one implementation manner of the present invention. The "in one embodiment" that appears in different places in this specification does not all refer to the same embodiment, nor is it an embodiment that is separate or selectively mutually exclusive with other embodiments.

[0067] Embodiment 1:

[0068] Referring to Figure 1 , it is the first embodiment of the present invention. This embodiment provides a high-temperature resistant polyurethane elastomer, which includes the following specific components: polyether polyol, polymethylene polyphenyl polyisocyanate pMDI, chain extender, and crosslinking agent.

[0069] The mass parts of the above components are as follows:

[0070] The polyether polyol is 70 parts;

[0071] The pMDI is 20 parts;

[0072] The chain extender is 5 parts;

[0073] The crosslinking agent is 1 part.

[0074] Among the specific components:

[0075] The polyether polyol is selected from high molecular weight polyether diols (molecular weight 3000 - 4000), such as polytetrahydrofuran ether diol (PTMG) or polypropylene glycol (PPG), or modified polyether triols (introducing partial aromatic groups or silicon-based structures), such as polydimethylsiloxane ether (PDMS) or polyether amide compounds.

[0076] The high-temperature stable polyether polyol, as the flexible segment of the high-temperature resistant polyurethane elastomer, plays a core role in determining the flexibility and elasticity of the entire elastomer system. Its properties determine the mechanical properties and creep resistance of the elastomer under high-temperature conditions. The selection of the molecular weight of the polyether polyol directly affects the elongation at break and resilience of the elastomer. A higher molecular weight helps to form longer flexible chain segments, thereby improving the tensile strength and flexibility of the material, and ensuring the creep resistance in a high-temperature environment.

[0077] The pMDI is selected from polyphenylene polymethylene polyisocyanate.

[0078] The benzene ring structure of pMDI gives it strong thermal stability and rigid support under high-temperature conditions. Its structural characteristics make the hard segment not easily soften and degrade at high temperatures, thus ensuring that the elastomer can still maintain high modulus and stability at 200 °C or even higher temperatures.

[0079] The chain extender is selected from 1,4-butanediol BDO, diethylene glycol DEG or 1,6-hexanediol HDO.

[0080] During the reaction process, BDO reacts with pMDI to form hard segment linkages, playing a dual role of chain extension and crosslinking. Its linear structure helps to form regularly arranged hard segment domains, thus forming a hard / soft segment phase separation structure microscopically.

[0081] By regulating the addition amount of BDO, the mechanical properties and heat distortion temperature of the polyurethane elastomer can be effectively adjusted. Increasing the BDO content can improve the tensile strength and wear resistance of the elastomer, but may lead to a certain degree of decrease in flexibility. Therefore, in the specific composition, it is necessary to balance hardness and flexibility to ensure that the elastomer can maintain structural strength at high temperatures and also have a certain degree of flexibility and extensibility.

[0082] The crosslinking agent is selected as trimethylolpropane TMP.

[0083] The introduction of TMP is mainly to enhance the three-dimensional crosslinking density of the elastomer and form a stable network crosslinked structure. This structure can effectively improve the dimensional stability and solvent resistance of the material at high temperatures, preventing deformation and degradation under long-term high-temperature action.

[0084] The content of the crosslinking agent directly affects the hardness and elastic recovery rate of the elastomer. An appropriate amount of TMP can ensure hardness while enabling the material to maintain high toughness and impact resistance. Due to the presence of the trifunctional group structure, the crosslinking bonds formed by TMP can provide strong support at high temperatures, significantly improving the thermal stability and anti-aging ability of the material.

[0085] On the basis of meeting the basic elastic properties, the above-mentioned composition endows the material with excellent performance at high temperatures. These components form a hard / soft segment phase separation structure through chemical reactions and physical crosslinking, thus ensuring that the elastomer has excellent creep resistance, tensile strength and thermal stability in a high-temperature environment.

[0086] The high-temperature resistant polyurethane elastomer also includes additives, and the additives specifically include nanoaluminum silicate fiber, titanium phosphate-based temperature-resistant synergist, multi-walled carbon nanotube grafted amide group, and metal-organic framework composite material.

[0087] The nanoaluminum silicate fiber is 2 parts.

[0088] The fiber diameter of the nanoaluminum silicate fiber is 20 - 50 nm, and the length is 1 - 5 μm. The surface is chemically activated by a surface activator; the surface activator is a coupling agent containing an organosilicon group, including γ-aminopropyltriethoxysilane KH-550, which is used to improve the dispersibility and compatibility of the nanoaluminum silicate fiber in the polyurethane elastomer.

[0089] Nano - aluminosilicate fiber has extremely high thermal stability and excellent mechanical reinforcement properties, and can exist stably for a long time above 300 °C. Its ultra - fine fiber structure forms a network - like skeleton in the polyurethane elastomer, enhancing the physical and chemical cross - links between polymer chains, and significantly improving the high - temperature resistance and tensile strength of the material. Through surface activation treatment, the surface of nano - aluminosilicate fiber carries active groups, which can be uniformly dispersed in the polyurethane matrix and form a stable interfacial layer with the matrix material through chemical bonding. This property effectively prevents interfacial peeling and mechanical property deterioration under high - temperature conditions. In addition, the fiber - reinforced network structure can effectively inhibit the thermal motion of chain segments and significantly improve the high - temperature deformation recovery ability of the material.

[0090] Compared with traditional fillers such as silica or carbon black, the ultra - high thermal stability nano - aluminosilicate fiber has the following innovative advantages:

[0091] Ultra - high heat resistance: Traditional fillers tend to agglomerate or fail at high temperatures, while nano - aluminosilicate fiber can still maintain stable mechanical properties above 300 °C.

[0092] Uniform dispersibility: Through surface activation and graft modification, it forms a stable dispersion in the matrix, avoiding agglomeration.

[0093] Rigidity enhancement effect: It forms a rigid skeleton support structure, significantly improving the creep resistance and deformation resistance of polyurethane elastomer in high - temperature environments.

[0094] In this embodiment, the expression of the surface silanization of nano - aluminosilicate fiber is as follows:

[0095] Al2SiO5-(OH) n +Si(OC2H5)3→Al2SiO5-(O - Si(OC2H5)3) n +nH2O;

[0096] During the surface treatment process of nano - aluminosilicate fiber (Al2SiO5), by reacting with the coupling agent KH - 550 (γ - aminopropyltriethoxysilane) containing an organosilicon group, a silyl group is introduced onto the fiber surface. This reaction is carried out in the presence of a solvent and under appropriate acid - catalyzed conditions, and water molecules are generated as by - products during the reaction process.

[0097] Since the triethoxysilyl group (-Si(OC2H5)3) in the KH - 550 molecule can combine with the hydroxyl groups on the fiber surface to form stable silicon - oxygen bonds, surface functionalization is achieved. This greatly enhances the compatibility and bonding strength between the fiber and the polyurethane matrix.

[0098] The titanium phosphate - based temperature - resistant synergist is 1 part.

[0099] Titanium phosphate-based heat-resistant synergists include titanium phosphate TiP2O7 and nano-titanate TiO3 2- Titanium phosphate is used to form a titanate protective layer at high temperature, effectively blocking oxidative degradation reactions; Nano titanate forms a dense interface layer in polyurethane elastomer through adsorption and complexation. Nano titanate is prepared by the sol-gel method with a particle size of 50-100nm.

[0100] In a high-temperature thermal oxidation environment, titanate can block the penetration of oxygen molecules and prevent the oxidative degradation of the elastomer. Nano-titanate particles form a dense interface layer with the polyurethane elastomer through adsorption and complexation, further improving the material's anti-oxidation and high-temperature resistance.

[0101] Compared with traditional antioxidants such as phenolic antioxidants or amine antioxidants, this synergist has the following advantages:

[0102] Dual protection mechanism: through chemical adsorption and titanate layer protection, it exhibits excellent thermal stability in high temperature oxidative environment.

[0103] Long-term heat resistance: Traditional antioxidants lose effectiveness quickly at high temperatures, while titanium phosphate-based synergists can work stably above 300°C.

[0104] Inhibit degradation rate: effectively delay the breakage and oxidative degradation of polyurethane chain segments, thereby improving the long-term performance of the material.

[0105] The antioxidant reaction of titanium phosphate-based heat-resistant synergist is shown below:

[0106] TiP2O7→TiO2+P2O5;

[0107] In a high-temperature thermal oxidation environment, titanium phosphate is decomposed by heat to form titanium dioxide and phosphorus pentoxide. Among them, titanium dioxide forms a dense protective film, while phosphorus pentoxide forms a phosphate layer on the surface of polyurethane, further improving its anti-oxidation and heat resistance.

[0108] The amount of multi-walled carbon nanotube grafted amide groups is 0.5 parts.

[0109] The multi-walled carbon nanotube grafted amide group comprises multi-walled carbon nanotubes MWCNTs and a grafted group; the diameter of the multi-walled carbon nanotubes is 20-30nm and the length is 2-10μm; the grafted group is an amide group -CONH2, and the grafting modification is performed after acidification treatment.

[0110] Carbon nanotubes have excellent thermal conductivity and mechanical reinforcement effects, but their surface inertness leads to poor compatibility with polyurethane matrix. By introducing amide groups, the chemical compatibility and physical adsorption capacity of carbon nanotubes and polyurethane molecules are significantly enhanced, forming a stable cross-linked network.

[0111] The modified carbon nanotubes can form heat conduction channels in the matrix, greatly improving the thermal conductivity of the material, thereby quickly dissipating heat and preventing local heat accumulation. At the same time, their enhanced mechanical strength ensures that the elastomer is not easily softened or broken at high temperatures.

[0112] The metal-organic framework composite material is 3 parts.

[0113] The metal-organic framework composite material includes titanium-organic framework Ti-MOF and a modifying group; the titanium-organic framework forms a microporous structure in the polyurethane elastomer through the molecular sieve effect; the modifying group is a carboxylic acid group -COOH, which is used to enhance the interfacial compatibility.

[0114] Through the molecular sieve effect, a microporous structure can be formed in the polyurethane matrix, effectively hindering the penetration of oxygen and moisture, and significantly improving the aging resistance and thermal stability of the material. At the same time, it has a highly ordered pore structure, which helps to quickly conduct and release heat, preventing decomposition caused by local overheating.

[0115] The thermal stability is significantly improved: compared with traditional fillers, the MOF material can still maintain its complete structure above 400 °C.

[0116] Multiple protection effects: it not only has a physical isolation effect but also can enhance the mechanical support ability of the material.

[0117] Reduce the risk of thermal oxidation: The microporous structure effectively blocks the diffusion of oxygen molecules and reduces high-temperature oxidative degradation.

[0118] Example 2:

[0119] Refer to Figure 2 , which is the second embodiment of the present invention. This embodiment provides a preparation method of a high-temperature resistant polyurethane elastomer, which is prepared based on the high-temperature resistant polyurethane elastomer described in Example 1, and includes the following specific steps:

[0120] S1. Prepare a polyurethane prepolymer;

[0121] Mix polyether polyol and pMDI according to the mass parts, put them into a reaction kettle, control the temperature at 90 °C, and the reaction time is 2 hours to obtain a polyurethane prepolymer.

[0122] S2. Introduce nano-aluminum silicate fiber;

[0123] Add nano-aluminum silicate fiber to the polyurethane prepolymer obtained in step S1, and use a high-shear stirrer to stir to ensure the uniform dispersion of nano-aluminum silicate fiber in the polyurethane matrix.

[0124] The particle size of the nano-aluminum silicate fiber is controlled below 50 nm. When using a high-shear stirrer for mixing, the stirring temperature is set at 70 °C and stirring continues for 30 minutes.

[0125] The introduction of nano - aluminosilicate fiber can significantly improve the thermal stability and high - temperature resistance of polyurethane elastomers, while enhancing the rigidity of its structure and the ability to resist deformation. This fiber material has an extremely high specific surface area and microstructure, can maintain its stability at extremely high temperatures, and at the same time enhance the thermal insulation effect of polyurethane materials. Compared with traditional reinforcing materials (such as glass fiber or carbon fiber), nano - aluminosilicate fiber has better dispersibility and stronger high - temperature resistance. Therefore, it can provide more unique advantages for the high - temperature applications of polyurethane elastomers.

[0126] S3. Add chain extender;

[0127] Add a chain extender to the polyurethane prepolymer in step S2. The chain extender reacts with the unreacted isocyanate groups in the polyurethane to increase the chain length of the polyurethane molecules and enhance the wear resistance and thermal stability of the material. The reaction is carried out at 80 °C for 1 hour.

[0128] S4. Form a preliminary polyurethane elastomer;

[0129] Transfer the polyurethane prepolymer obtained from the reaction in step S3 to a reaction mold and perform hot - pressing molding on it. The mold temperature is set at 100 °C, the pressure is 5 MPa, and the reaction time is 2 hours, and the polyurethane elastomer is preliminarily shaped.

[0130] S5. Introduce cross - linker;

[0131] Add a cross - linker to the preliminary polyurethane elastomer. The cross - linker forms a three - dimensional network structure through the reaction between polyurethane molecules, further improving the thermal stability, compressive strength, and wear resistance of the material. The reaction temperature is set at 90 °C for 1 hour.

[0132] S6. Add multi - walled carbon nanotubes grafted with amide groups;

[0133] Add multi - walled carbon nanotubes grafted with amide groups to the polyurethane elastomer obtained in step S5 and use a high - shear stirrer for uniform dispersion. The carbon nanotubes enhance their dispersion in the polyurethane matrix by grafting amide groups, improving their thermal conductivity, mechanical strength, and high - temperature resistance. The stirring temperature is controlled at 80 °C and the stirring time is 30 minutes.

[0134] The steps for grafting amide groups onto multi - walled carbon nanotubes are as follows:

[0135] Dissolve multi - walled carbon nanotubes in N,N - dimethylacetamide solvent and add an amination reagent to the solution for amidation reaction;

[0136] Under nitrogen protection, the reaction temperature was controlled at 60 °C and the reaction time was 3 hours to ensure that the amide groups reacted fully with the surface of the multi-walled carbon nanotubes and the grafting amount reached the required level.

[0137] Generally, multi-walled carbon nanotubes are used to enhance the electrical conductivity and mechanical properties of materials. However, by grafting amide groups, their dispersibility in the polyurethane matrix is greatly improved. As hydrophilic groups, the amide groups contribute to the affinity of carbon nanotubes in the polyurethane matrix, thus avoiding the problem that traditional carbon nanotubes are difficult to disperse evenly in polyurethane. This innovative treatment method enables multi-walled carbon nanotubes to not only effectively enhance the thermal conductivity and mechanical strength, but also further improve the high-temperature performance of the materials. Compared with the direct use of ungrafted carbon nanotubes in the prior art, this method has obvious advantages in improving the dispersibility and functionality of carbon nanotubes.

[0138] S7. Add a titanium phosphate-based high-temperature resistant synergist;

[0139] In the polyurethane elastomer obtained in step S6, a titanium phosphate-based high-temperature resistant synergist was added. Titanium phosphate has good high-temperature resistance and can effectively improve the thermal stability of polyurethane. By introducing this synergist, the stability of the material in a high-temperature environment was enhanced, and at the same time, the oxidation resistance of the polyurethane elastomer was improved. The reaction temperature was controlled at 100 °C and the reaction time was 1 hour.

[0140] S8. Introduce a metal-organic framework composite material;

[0141] The metal-organic framework composite material was added to the polyurethane elastomer obtained in step S7 and subjected to high-efficiency stirring. The metal-organic framework composite material has a high specific surface area and thermal stability, can provide better structural support in a high-temperature environment, and enhance the thermal conductivity, heat resistance, and compressive strength of polyurethane. After stirring, curing was carried out to obtain the final high-temperature resistant polyurethane elastomer.

[0142] The amount of the metal-organic framework composite material added was controlled at 1-5 wt%, and a high-shear stirrer was used to uniformly mix the metal-organic framework composite material with the polyurethane elastomer. The stirring temperature was controlled at 60 °C and the stirring time was 30 minutes.

[0143] Metal-organic framework (MOFs) materials are usually applied in fields such as gas storage and separation. However, using them for the reinforcement of polyurethane elastomers is the first time in this field. MOFs have a highly adjustable pore structure and a high specific surface area, can effectively provide thermal insulation and stability support in a high-temperature environment, and greatly enhance the performance of polyurethane in a harsh environment. In addition, the addition of MOFs also helps to improve the thermal conductivity of polyurethane, which is particularly suitable for high-performance materials requiring thermal management.

[0144] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and all of them should be covered by the scope of the claims of the present invention.

Claims

1. A high temperature resistant polyurethane elastomer, characterized in that: It includes the following specific components: polyether polyol, polytoluene diisocyanate pMDI, chain extender, crosslinking agent; The mass fractions of the above ingredients are as follows: Polyether polyol is 70-80 parts; pMDI is 20-25 parts; The chain extender is 5-10 parts; The cross-linking agent is 1-3 parts; The high temperature resistant polyurethane elastomer also includes additives, which specifically include nano aluminum silicate fibers, titanium phosphate-based temperature resistant synergist, multi-walled carbon nanotube grafted amide groups, and metal organic framework composite materials; Nano-aluminum silicate fiber is 2-5 parts; The titanium phosphate-based heat-resistant synergist is 1-3 parts; The multi-walled carbon nanotubes are grafted with amide groups in an amount of 0.5-2 parts; The metal organic framework composite material is 3-6 parts.

2. A high temperature resistant polyurethane elastomer according to claim 1, characterized in that: Among the specific components: The polyether polyol is selected from high molecular weight polyether diol or modified polyether triol; pMDI uses polyphenylene polymethyl polyisocyanate; The chain extender is 1,4-butanediol BDO, diethylene glycol DEG or 1,6-hexanediol HDO; The crosslinking agent is trimethylolpropane TMP.

3. A high temperature resistant polyurethane elastomer according to claim 1, characterized in that: In the additive, the nano aluminum silicate fiber has a fiber diameter of 20-50 nm and a length of 1-5 μm, and a surface active agent is used to perform chemical activation treatment on the surface; The surfactant adopts a coupling agent containing an organic silicon group, including γ-aminopropyltriethoxysilane KH-550, which is used to improve the dispersibility and compatibility of the nano-aluminum silicate fiber in the polyurethane elastomer.

4. A high temperature resistant polyurethane elastomer according to claim 1, characterized in that: Among the additives, the titanium phosphate-based temperature-resistant synergist includes titanium phosphate TiP2O7 and nano titanate TiO3 2- ; Titanium phosphate is used to form a titanate protective layer at high temperatures, effectively blocking oxidative degradation reactions; The nano titanate forms a dense interface layer in the polyurethane elastomer through adsorption and complexation. The nano titanate is prepared by a sol-gel method and has a particle size of 50-100 nm.

5. The high temperature resistant polyurethane elastomer according to claim 1, characterized in that: In the additive, the multi-walled carbon nanotube grafted amide group comprises multi-walled carbon nanotubes MWCNTs and a grafted group; Multi-walled carbon nanotubes have a diameter of 20-30 nm and a length of 2-10 μm; The grafted group is an amide group -CONH2, which is grafted and modified after acidification.

6. The high temperature resistant polyurethane elastomer according to claim 1, characterized in that: In the additive, the metal organic framework composite material includes titanium-organic framework Ti-MOF and a modifying group; The titanium-organic framework forms a microporous structure in the polyurethane elastomer through the molecular sieve effect; The modified group is a carboxylic acid group -COOH, which is used to enhance the interfacial compatibility.

7. A method for preparing a high temperature resistant polyurethane elastomer, based on the high temperature resistant polyurethane elastomer according to any one of claims 1 to 6, characterized in that: The specific steps include: S1, preparing a polyurethane prepolymer; The polyether polyol and pMDI were mixed according to the mass fractions, put into a reaction kettle, the temperature was controlled at 90° C., and the reaction time was 2 hours to obtain a polyurethane prepolymer; S2, introduction of nano-aluminum silicate fibers; Adding the nano-aluminum silicate fibers to the polyurethane prepolymer obtained in step S1, and stirring using a high shear stirrer to ensure uniform dispersion of the nano-aluminum silicate fibers and the polyurethane matrix; S3, adding chain extender; Adding a chain extender to the polyurethane prepolymer in step S2, wherein the chain extender reacts with unreacted isocyanate groups in the polyurethane, and the reaction is carried out at 80° C. for 1 hour; S4, forming a preliminary polyurethane elastomer; The polyurethane prepolymer obtained by the reaction in step S3 is transferred to a reaction mold and subjected to hot pressing molding. The mold temperature is set to 100° C., the pressure is 5 MPa, and the reaction time is 2 hours. The polyurethane elastomer is initially formed. S5, introducing a cross-linking agent; A crosslinking agent was added to the preliminary polyurethane elastomer, the reaction temperature was set to 90°C, and the reaction time was 1 hour; S6, adding multi-walled carbon nanotube grafted amide groups; Add the multi-walled carbon nanotube grafted amide groups to the polyurethane elastomer obtained in step S5, and use a high shear stirrer to evenly disperse it. The stirring temperature is controlled at 80° C. and the stirring time is 30 minutes. S7, adding a titanium phosphate-based temperature-resistant synergist; A titanium phosphate-based temperature-resistant synergist is added to the polyurethane elastomer obtained in step S6, and the reaction temperature is controlled at 100° C. for 1 hour; S8, introduction of metal organic framework composites; The metal organic framework composite material is added to the polyurethane elastomer obtained in step S7, and is efficiently stirred. After the stirring is completed, the mixture is cured to obtain a final high temperature resistant polyurethane elastomer.

8. The method for preparing a high temperature resistant polyurethane elastomer according to claim 7, characterized in that: In the step S2, the particle size of the nano-aluminum silicate fiber is controlled to be below 50 nm, and when a high shear stirrer is used for mixing, the stirring temperature is set to 70° C. and the stirring is continued for 30 minutes.

9. The method for preparing a high temperature resistant polyurethane elastomer according to claim 7, characterized in that: In step S6, the steps of grafting amide groups onto multi-walled carbon nanotubes are as follows: The multi-walled carbon nanotubes are dissolved in an N,N-dimethylacetamide solvent, and an amination agent is added to the solution to perform an amidation reaction; Under nitrogen protection, the reaction temperature was controlled at 60°C and the reaction time was 3 hours to ensure that the amide groups fully reacted with the surface of the multi-walled carbon nanotubes and the grafting amount reached the required level.

10. The method for preparing a high temperature resistant polyurethane elastomer according to claim 7, characterized in that: In the step S8, the amount of the metal organic framework composite material added is controlled to be 1-5 wt%, and the metal organic framework composite material and the polyurethane elastomer are uniformly mixed using a high shear mixer, the stirring temperature is controlled at 60° C., and the stirring time is 30 minutes.

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