High-temperature-resistant double-component polyurethane pouring sealant and preparation method thereof

Abstract

The invention belongs to the technical field of polyurethane materials, and particularly relates to a high-temperature-resistant double-component polyurethane pouring sealant and a preparation method thereof.The polyurethane pouring sealant comprises a component A and a component B. The component A comprises, by weight, 60-80 parts of polyisocyanate; 20 to 40 parts of polyether polyol A; 0.1 to 0.5 part of an antioxidant; the component B is prepared from the following components in parts by weight: 30 to 50 parts of composite polyol containing a benzoxazine ring; 15 to 25 parts of high-functionality polyether polyol B; 5-15 parts of a chain extender; 20-40 parts of a high-temperature-resistant filler; 0.05 to 0.2 part of a catalyst; 0.1 to 0.5 part of a defoaming agent; the weight ratio of the component A to the component B is 1: (1-4). The polyurethane pouring sealant product prepared by the invention is high in thermal decomposition temperature and excellent in performance retention rate after high-temperature aging, and meets the harsh requirements of high-end electronic and electric appliances on the heat resistance grade of the pouring sealant material.

Description

Technical Field

[0001] This invention relates to a high-temperature resistant two-component polyurethane potting compound and its preparation method, belonging to the field of polyurethane materials technology. Background Technology

[0002] Polyurethane potting compounds, as an important electronic and electrical insulation material, are widely used for the encapsulation and protection of electronic components, circuit boards, and modules due to their excellent electrical insulation properties, flexibility, adhesion, and ease of application. However, traditional polyurethane potting compounds have insufficient heat resistance, with long-term operating temperatures typically not exceeding 120°C. At high temperatures, polyurethane molecular chains are prone to thermal degradation and hydrolysis, leading to a decline in the material's mechanical properties, brittleness, and even pulverization, thus affecting its protective effect on components.

[0003] With the technological advancements in new energy vehicles, aerospace, high-speed rail transportation, and high-end industrial drives, core electronic components such as motor controllers, on-board chargers, power modules, and high-temperature sensors often require long-term stable operation at temperatures of 150°C or even higher. This places more stringent demands on the heat resistance of the potting compound materials used.

[0004] Currently, common techniques used in the industry to improve the heat resistance of polyurethane include introducing heat-resistant segments into the molecular chain, adding heat-resistant fillers, or blending with other heat-resistant resins. However, these methods often have limitations in practical applications. For example, introducing heat-resistant segments may lead to increased brittleness and decreased toughness of the material; the addition of a large amount of filler may affect the flowability and processability of the system and may impair its electrical properties; while blending with other resins often faces problems such as poor compatibility, phase separation, and poor storage stability.

[0005] Currently, methods to improve the heat resistance of polyurethane mainly include introducing heat-resistant segments, adding heat-resistant fillers, or modifying with other heat-resistant resins. However, these methods often involve complex processes, poor compatibility, or damage to other properties. Therefore, how to significantly improve the high-temperature resistance of polyurethane materials while maintaining their inherent advantages (such as excellent toughness, adhesion, and electrical properties) and ensuring good processability has become a technical challenge that urgently needs to be solved by those skilled in the art. Therefore, developing a two-component polyurethane potting compound that combines excellent high-temperature resistance, good processability, and comprehensive performance has significant practical importance and market value. Summary of the Invention

[0006] To address the aforementioned deficiencies in the prior art, this invention provides a high-temperature resistant two-component polyurethane potting compound and its preparation method.

[0007] The technical solution of the present invention to solve the above-mentioned technical problems is as follows: One objective of this invention is to provide a high-temperature resistant two-component polyurethane potting compound, comprising component A and component B. By weight, component A comprises: 60-80 parts of polyisocyanate; 20-40 parts of polyether polyol A; and 0.1-0.5 parts of antioxidant. By weight, component B comprises: 30-50 parts of a composite polyol containing a benzoxazine ring; 15-25 parts of a high-functionality polyether polyol B; 5-15 parts of a chain extender; 20-40 parts of a high-temperature resistant filler; 0.05-0.2 parts of a catalyst; and 0.1-0.5 parts of a defoamer. The weight ratio of component A to component B is 1:1 to 4.

[0008] Based on the above technical solution, the present invention can also be improved as follows: Furthermore, the polyisocyanate is selected from at least one of polyphenyl polymethylene polyisocyanate (PAPI), liquefied MDI, and polymeric MDI.

[0009] Furthermore, the polyisocyanate is a polyphenyl polymethylene polyisocyanate.

[0010] The advantages of using polyphenyl polymethylene polyisocyanate are that its multifunctionality can form a three-dimensional network structure with higher crosslinking density, and the large number of benzene ring structures provide an excellent rigid heat-resistant skeleton, so that the cured product has a higher heat distortion temperature and thermal stability.

[0011] Furthermore, the polyether polyol A is selected from at least one of polypropylene oxide diol, polytetrahydrofuran ether diol, and polyethylene oxide-propylene oxide copolyether diol, with a molecular weight of 1000 to 3000.

[0012] Furthermore, the polyether polyol A is polyoxypropylene glycol with a molecular weight of 1000-2000.

[0013] The advantages of using polypropylene glycol are that it provides moderate flexibility while having low viscosity and good hydrolytic stability, which is beneficial to the synthesis of prepolymers and subsequent processing performance.

[0014] Furthermore, the composite polyol containing the benzoxazine ring is prepared by a ring-opening addition reaction between benzoxazine resin and polyol C.

[0015] The advantages of using composite polyols containing benzoxazine rings are that they retain the high heat resistance and ring-opening polymerization characteristics of benzoxazine rings, while introducing polyol segments through chemical modification, improving compatibility with polyurethane systems, solving the problems of easy phase separation and severe thickening when directly adding benzoxazine resins, and achieving a balance between heat resistance and processability.

[0016] Furthermore, the benzoxazine resin is selected from at least one of bisphenol A type benzoxazine resin, bisphenol F type benzoxazine resin, and cashew phenol type benzoxazine resin; the polyol C is selected from at least one of polycaprolactone diol, polycarbonate diol, and polyether polyol, with a molecular weight of 400 to 1000.

[0017] Furthermore, the composite polyol containing the benzoxazine ring is prepared by reacting bisphenol A type benzoxazine resin with polycaprolactone diol at a mass ratio of 1:0.5 to 1.5.

[0018] Furthermore, the high-functionality polyether polyol B has a functionality of 3 to 6 and a molecular weight of 400 to 800; the high-functionality polyether polyol B is selected from at least one of propylene oxide-ethylene oxide co-polyether polyol and polyoxypropylene ether polyol.

[0019] Furthermore, the high-functionality polyether polyol B is selected from propylene oxide-ethylene oxide copolyether polyols with a functionality of 4 to 6.

[0020] The advantages of using the above-mentioned high-functionality polyether polyol B are that it can provide more crosslinking points, increase crosslinking density, improve the hardness, strength and heat resistance of the material, and the introduction of ethylene oxide segments helps to improve compatibility with other components.

[0021] Furthermore, the chain extender is selected from at least one of 3,3'-dichloro-4,4'-diaminodiphenylmethane (MOCA), diethyltoluenediamine (DETDA), dimethylthiotoluenediamine (DMTDA), 1,4-butanediol (BDO), and ethylene glycol (EG).

[0022] Furthermore, the chain extender is 3,3'-dichloro-4,4'-diaminodiphenylmethane (MOCA).

[0023] The advantages of using MOCA are as follows: it is an aromatic amine chain extender that reacts with NCO to form urea bonds. The thermal decomposition temperature of urea bonds is significantly higher than that of urethane bonds. In addition, the rigid aromatic ring structure of MOCA molecules itself is also conducive to improving the thermal stability of hard segment microregions, thereby significantly improving high-temperature performance.

[0024] Furthermore, the high-temperature resistant filler is selected from at least one of nano-alumina, nano-silica, micron-sized alumina, silica powder, aluminum hydroxide, and magnesium hydroxide, preferably nano-alumina ceramic powder with a particle size of 20-50 nm; the high-temperature resistant filler needs to be surface-treated with a silane coupling agent; the silane coupling agent is selected from at least one of γ-aminopropyltriethoxysilane (KH-550), γ-(2,3-epoxypropoxy)propyltrimethoxysilane (KH-560), and γ-methacryloyloxypropyltrimethoxysilane (KH-570); preferably γ-aminopropyltriethoxysilane (KH-550), and its dosage is 1.5%-2.5% of the filler weight.

[0025] The beneficial effects of adopting the above-mentioned nano-alumina and silane coupling agent treatment are as follows: nano-alumina itself has high thermal conductivity, high insulation and excellent thermal stability. After treatment with silane coupling agent, it has good compatibility with the matrix resin and is evenly dispersed. It can not only effectively reinforce, but also act as a physical crosslinking point to restrict the thermal movement of molecular chains. At the same time, it helps to dissipate heat and improve the overall heat resistance.

[0026] Furthermore, the antioxidant is selected from at least one of antioxidant 1010, antioxidant 1076, antioxidant 168, and antioxidant 245.

[0027] Furthermore, the antioxidant is preferably antioxidant 1010; antioxidant 1010, as a highly efficient hindered phenolic antioxidant, can effectively capture free radicals, inhibit the oxidative degradation of polyurethane materials at high temperatures, and improve the thermo-oxidative stability of the materials.

[0028] Furthermore, the catalyst is selected from at least one of organobismuth catalysts, organotin catalysts, and amine catalysts.

[0029] Furthermore, the catalyst is preferably an organic bismuth catalyst, which has high catalytic activity, good selectivity for the NCO / OH reaction, and is environmentally friendly and low in toxicity, which is beneficial for controlling the reaction rate and the curing process.

[0030] Furthermore, the defoamer is selected from at least one of silicone defoamers and non-silicone defoamers.

[0031] Furthermore, the defoamer is preferably an organosilicone defoamer; organosilicone defoamers have low surface tension and strong defoaming ability, which can effectively eliminate bubbles generated during stirring and potting, ensuring the tightness and electrical insulation reliability of the package.

[0032] The second objective of this invention is to provide a method for preparing the above-mentioned high-temperature resistant two-component polyurethane potting compound, comprising the following steps: S1. Preparation of Component A: Under a dry protective atmosphere, add polyisocyanate and antioxidant to the reactor, heat to 60±5℃ and stir evenly; under continuous stirring, slowly add pre-vacuum dehydrated polyether polyol A; after the addition is complete, raise the system temperature to 85±5℃ and react for 3 to 5 hours; after the reaction is complete, cool to below 50℃, discharge, seal and package to obtain Component A; S2. Preparation of component B: Under vacuum conditions, the composite polyol containing benzoxazine ring, high-functionality polyether polyol B, chain extender, high-temperature resistant filler, catalyst and defoamer are mixed and stirred under vacuum at 60-70°C for 1-2 hours until homogeneous; cooled to room temperature, discharged, sealed and packaged to obtain component B.

[0033] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention, through the synergistic effect of polyisocyanate, self-synthesized benzoxazine-containing composite polyol, chain extender, and nanoscale heat-resistant filler, greatly improves the high-temperature resistance of potting compound without sacrificing processability and mechanical properties. The resulting polyurethane potting compound has a long-term service temperature exceeding 180°C, a high thermal decomposition temperature, and excellent performance retention after high-temperature aging, fully meeting the stringent requirements of high-end electronic appliances for the heat resistance of potting materials. Detailed Implementation

[0034] The principles and features of the present invention are described below. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0035] Example 1 1. Preparation of Component A Under dry nitrogen protection, 70 parts by weight of PAPI and 0.3 parts by weight of antioxidant 1010 were added to the reactor, and the temperature was raised to 60°C and stirred until homogeneous. While continuously stirring, 30 parts by weight of polypropylene glycol (molecular weight 2000), which had been pre-dehydrated under vacuum at 120°C for 2 hours, were slowly added dropwise. After the addition was complete, the system temperature was raised to 85°C, and the reaction was allowed to proceed for 4 hours. After the reaction was completed, the mixture was cooled to 40°C, discharged, sealed, and packaged to obtain component A.

[0036] 2. Preparation of Component B Preparation of composite polyols containing benzoxazine rings: 20 parts by weight of bisphenol A type benzoxazine resin and 20 parts by weight of polycaprolactone diol (molecular weight 530) were added to a reactor and stirred at 100°C for 1.5 hours until the system became homogeneous and transparent. After cooling, composite polyols containing benzoxazine rings were obtained.

[0037] Preparation of high-temperature resistant filler: 30 parts by weight of nano alumina powder (particle size of 30 nm) were dried at 120°C for 4 hours, and then mixed at high speed with 0.6 parts by weight of KH-550 coupling agent in ethanol solution. The ethanol was then dried to remove the ethanol and the high-temperature resistant filler was obtained.

[0038] Preparation of Component B: Under vacuum conditions, 40 parts by weight of a benzoxazine-containing composite polyol, 20 parts by weight of a propylene oxide-ethylene oxide copolyether polyol (functionality 4, molecular weight 600), 10 parts by weight of MOCA, 0.1 parts by weight of an organobismuth catalyst, and 0.3 parts by weight of an organosilicon defoamer were sequentially added to a planetary mixer. Finally, 30 parts by weight of a pre-treated high-temperature resistant filler were added. The mixture was stirred and mixed at 65°C and a vacuum of -0.097 MPa for 1.5 hours until homogeneous. After cooling to room temperature, the mixture was discharged, sealed, and packaged to obtain Component B.

[0039] Example 2 1. The preparation of component A is the same as in Example 1.

[0040] 2. Preparation of Component B Preparation of composite polyol containing benzoxazine ring: 17.5 parts by weight of bisphenol A type benzoxazine resin and 17.5 parts by weight of polycaprolactone diol (molecular weight 530) were added to a reactor and stirred at 100°C for 1.5 hours until the system became homogeneous and transparent. After cooling, the composite polyol containing benzoxazine ring was obtained.

[0041] Preparation of high-temperature resistant filler: 25 parts by weight of nano alumina powder (particle size of 30 nm) were dried at 120 °C for 4 hours, and then mixed at high speed with 0.5 parts by weight of KH-550 coupling agent in ethanol solution. The ethanol was then dried to remove the ethanol and the high-temperature resistant filler was obtained.

[0042] Preparation of Component B: Under vacuum conditions, 35 parts by weight of a benzoxazine-containing composite polyol, 20 parts by weight of a propylene oxide-ethylene oxide copolyether polyol (functionality 4, molecular weight 600), 10 parts by weight of MOCA, 0.1 parts by weight of an organobismuth catalyst, and 0.3 parts by weight of an organosilicon defoamer were sequentially added to a planetary mixer. Finally, 25 parts by weight of a pre-treated high-temperature resistant filler were added. The mixture was stirred and mixed at 65°C and a vacuum of -0.097 MPa for 1.5 hours until homogeneous. After cooling to room temperature, the mixture was discharged, sealed, and packaged to obtain Component B.

[0043] Example 3 1. The preparation of component A is the same as in Example 1; 2. Preparation of Component B Preparation of composite polyol containing benzoxazine ring: 22.5 parts by weight of bisphenol A type benzoxazine resin and 22.5 parts by weight of polycaprolactone diol (molecular weight 530) were added to a reactor and stirred at 100°C for 1.5 hours until the system became homogeneous and transparent. After cooling, the composite polyol containing benzoxazine ring was obtained.

[0044] Preparation of high-temperature resistant filler: 35 parts by weight of nano alumina powder (particle size of 30 nm) were dried at 120 °C for 4 hours, and then mixed at high speed with 0.7 parts by weight of KH-550 coupling agent in ethanol solution. The ethanol was then dried to remove the ethanol and the high-temperature resistant filler was obtained.

[0045] Preparation of Component B: Under vacuum conditions, 45 parts by weight of a benzoxazine-containing composite polyol, 20 parts by weight of a propylene oxide-ethylene oxide copolyether polyol (functionality 4, molecular weight 600), 10 parts by weight of MOCA, 0.1 parts by weight of an organobismuth catalyst, and 0.3 parts by weight of an organosilicon defoamer were sequentially added to a planetary mixer. Finally, 35 parts by weight of the pre-treated high-temperature resistant filler were added. The mixture was stirred and mixed at 65°C and -0.097 MPa vacuum for 1.5 hours until homogeneous. After cooling to room temperature, the mixture was discharged, sealed, and packaged to obtain Component B.

[0046] Comparative Example 1 1. The preparation of component A is the same as in Example 1.

[0047] 2. Preparation of Component B Instead of adding a benzoxazine-containing composite polyol, 60 parts by weight of propylene oxide-ethylene oxide copolyether polyol (functionality 4, molecular weight 600) were used. Other components, dosages, and preparation methods were the same as in Example 1.

[0048] Comparative Example 2 1. The preparation of component A is the same as in Example 1.

[0049] 2. Preparation of Component B Without adding nano alumina powder, the amount of propylene oxide-ethylene oxide copolyether polyol was increased to 55 parts by weight, and the other components, amounts, and preparation methods were the same as in Example 1.

[0050] Comparative Example 3 1. The preparation of component A is the same as in Example 1.

[0051] 2. Preparation of Component B Without adding MOCA chain extender, the amount of propylene oxide-ethylene oxide copolyether polyol was increased to 30 parts by weight, and the other components, amounts, and preparation methods were the same as in Example 1.

[0052] test The polyurethane potting compounds prepared in the examples and comparative examples were mixed at a weight ratio of component A: component B = 1:1.5, poured into molds, cured at 80°C for 3 hours, and then cured at 120°C for 2 hours to obtain test samples for the following performance tests. The results are shown in Table 1.

[0053] 1. Long-term heat resistance temperature Refer to GB / T 11026.1-2016 "Heat resistance of electrical insulation materials - Part 1: Aging procedures and evaluation of test results".

[0054] 2. TGA 5% Thermogravimetric Temperature (Td5%) According to ASTM E1131-20, "Standard Method for Compositional Analysis Using Thermogravimetric Analysis", nitrogen atmosphere was used, and the heating rate was 10℃ / min.

[0055] 3. Tensile strength retention rate after aging at 180℃ / 1000h Aging was carried out in accordance with GB / T 7141-2008 "Test Method for Thermal Aging of Plastics", and the tensile strength test after aging was carried out in accordance with GB / T 528-2009 "Determination of Tensile Stress-Strain Properties of Vulcanized Rubber or Thermoplastic Rubber".

[0056] 4. Tensile strength Refer to GB / T 528-2009 "Determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber".

[0057] 5. Elongation at break Refer to GB / T 528-2009 "Determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber".

[0058] 6. Volume resistivity Refer to GB / T 1410-2006 "Test methods for volume resistivity and surface resistivity of solid insulating materials".

[0059] 7. Electrical strength Refer to GB / T 1408.1-2016 "Test methods for electrical strength of insulating materials - Part 1: Test at power frequency".

[0060] Table 1 Comparison of performance test data results between the examples and the comparative examples

[0061] This invention synthesizes a composite polyol containing a benzoxazine ring and applies it to a two-component polyurethane system, resolving the contradiction between high temperature resistance, high toughness, and good processability in polyurethane potting compounds. This makes it suitable for high-temperature electronic applications such as new energy vehicle electronic control systems. The performance advantages are clearly derived from the test data in Table 1 combined with the microscopic mechanism of the invention's technical solution: the composite polyol containing a benzoxazine ring (obtained by ring-opening addition of benzoxazine resin and polycaprolactone diol) is the core of the improved heat resistance. The rigid aromatic ring structure of the retained benzoxazine ring can form a high-density cross-linked three-dimensional network to restrict the thermal motion of molecular chains. The polyol segments also improve the compatibility with the polyurethane system. Compared with Comparative Example 1 (without this substance, long-term heat resistance temperature 155℃, TGA 5% thermogravimetric temperature 275℃, 180℃ / 1000h), the performance is significantly improved. The tensile strength retention rate after aging was 62%. Examples 1-3 (with the addition of this composite polyol) all had long-term heat resistance temperatures exceeding 180℃, thermogravimetric temperatures reaching 298-308℃, and performance retention rates after high-temperature aging of 85%-88%. Nano-alumina fillers treated with KH-550 silane coupling agent can serve as physical crosslinking points and dissipate heat through high thermal conductivity. Compared to Comparative Example 2 (long-term heat resistance temperature 165℃, tensile strength retention rate after high-temperature aging 75%), Examples 1-3 (with 25-35 parts by weight of this filler) maintained good mechanical properties while improving thermal stability. MOCA chain extender reacts with isocyanate to generate urea bonds with higher thermal decomposition temperatures. Its rigid aromatic ring structure enhances the thermal stability of the hard segment microregions. Compared to Comparative Example 3 (long-term heat resistance temperature 160℃, tensile strength retention rate after high-temperature aging 70%), Examples 1-3... This ensures a balance of mechanical properties at high temperatures (elongation at break 145%-160%), and the synergistic effect of these three factors stabilizes the product's electrical properties (volume resistivity 1.8×10¹). 5 -2.1×10¹ 5 Ω cm, electrical strength 26-27kV / mm).

[0062] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A high-temperature resistant two-component polyurethane potting compound, characterized in that, Includes component A and component B. By weight, component A comprises: 60-80 parts of polyisocyanate; 20-40 parts of polyether polyol A; and 0.1-0.5 parts of antioxidant. By weight, component B comprises: 30-50 parts of a composite polyol containing a benzoxazine ring; 15-25 parts of a high-functionality polyether polyol B; 5-15 parts of a chain extender; 20-40 parts of a high-temperature resistant filler; 0.05-0.2 parts of a catalyst; and 0.1-0.5 parts of a defoamer. The weight ratio of component A to component B is 1:1 to 4.

2. The high-temperature resistant two-component polyurethane potting compound according to claim 1, characterized in that, The polyisocyanate is selected from at least one of polyphenyl polymethylene polyisocyanate, liquefied MDI, and polymeric MDI.

3. The high-temperature resistant two-component polyurethane potting compound according to claim 1, characterized in that, The polyether polyol A is selected from at least one of polypropylene oxide diol, polytetrahydrofuran ether diol, and polyethylene oxide-propylene oxide copolyether diol.

4. The high-temperature resistant two-component polyurethane potting compound according to claim 1, characterized in that, The benzoxazine-containing composite polyol is prepared by a ring-opening addition reaction between benzoxazine resin and polyol C.

5. The high-temperature resistant two-component polyurethane potting compound according to claim 4, characterized in that, The benzoxazine resin is selected from at least one of bisphenol A type benzoxazine resin, bisphenol F type benzoxazine resin, and cashew phenol type benzoxazine resin; the polyol C is selected from at least one of polycaprolactone diol, polycarbonate diol, and polyether polyol.

6. The high-temperature resistant two-component polyurethane potting compound according to claim 5, characterized in that, The benzoxazine-containing composite polyol is prepared by reacting bisphenol A type benzoxazine resin with polycaprolactone diol at a mass ratio of 1:0.5 to 1.

5.

7. The high-temperature resistant two-component polyurethane potting compound according to claim 1, characterized in that, The high-functionality polyether polyol B has a functionality of 3 to 6; the high-functionality polyether polyol B is selected from at least one of propylene oxide-ethylene oxide co-polyether polyol and polyoxypropylene ether polyol.

8. The high-temperature resistant two-component polyurethane potting compound according to claim 1, characterized in that, The chain extender is selected from at least one of 3,3'-dichloro-4,4'-diaminodiphenylmethane, diethyltoluenediamine, dimethylthiotoluenediamine, 1,4-butanediol, and ethylene glycol.

9. The high-temperature resistant two-component polyurethane potting compound according to claim 1, characterized in that, The high-temperature resistant filler is selected from at least one of nano alumina, nano silica, micron alumina, silica powder, aluminum hydroxide, and magnesium hydroxide; the high-temperature resistant filler needs to be surface treated with a silane coupling agent; the silane coupling agent is selected from at least one of γ-aminopropyltriethoxysilane, γ-(2,3-epoxypropoxy)propyltrimethoxysilane, and γ-methacryloyloxypropyltrimethoxysilane.

10. A method for preparing a high-temperature resistant two-component polyurethane potting compound as described in any one of claims 1 to 9, characterized in that, Includes the following steps: S1. Preparation of Component A: Under a dry protective atmosphere, add polyisocyanate and antioxidant to the reactor, heat to 60±5℃ and stir evenly; under continuous stirring, slowly add pre-vacuum dehydrated polyether polyol A; after the addition is complete, raise the system temperature to 85±5℃ and react for 3 to 5 hours; after the reaction is complete, cool to below 50℃, discharge, seal and package to obtain Component A; S2. Preparation of component B: Under vacuum conditions, the composite polyol containing benzoxazine ring, high-functionality polyether polyol B, chain extender, high-temperature resistant filler, catalyst and defoamer are mixed and stirred under vacuum at 60-70°C for 1-2 hours until homogeneous; cooled to room temperature, discharged, sealed and packaged to obtain component B.

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