Hydrolysis-resistant polyurethane resin aerogel and preparation method thereof

Abstract

The invention relates to the technical field of thermal insulation materials, in particular to hydrolysis-resistant polyurethane resin aerogel and a preparation method thereof, and the hydrolysis-resistant polyurethane resin aerogel comprises the following components in parts by weight: 60-80 parts of polyether polyol, 30-50 parts of polyester polyol, 10-15 parts of modified silicon dioxide, 20-30 parts of isocyanate, 0.5-2 parts of a dispersing agent and 0.5-1 part of a catalyst. According to the technical scheme, through chemical bonding of amino groups on the surface of modified silicon dioxide and isocyanate, molecular-level combination of filler and a polyurethane matrix is achieved, the comprehensive performance of the material is remarkably improved, and the prepared polyurethane resin aerogel is promoted to have multiple functions of heat insulation, hydrolysis resistance, flame retardance, aging resistance and the like.

Description

Technical Field

[0001] This invention relates to the field of thermal insulation materials, and in particular to a hydrolysis-resistant polyurethane resin aerogel and its preparation method. Background Technology

[0002] Polyurethane aerogel, as a novel porous material, possesses excellent properties such as low density, high porosity, and low thermal conductivity, demonstrating enormous application potential in the field of thermal insulation materials. Compared with traditional insulation materials, polyurethane aerogel not only has superior thermal insulation performance but also features lightweight, high mechanical strength, and good weather resistance, meeting the demands of modern construction, aerospace, petrochemical, and other fields for high-performance thermal insulation materials. Especially under extreme environmental conditions, such as high temperature, high humidity, and corrosive environments, the thermal insulation performance of polyurethane aerogel is irreplaceable.

[0003] In the prior art, CN202011147032.6 discloses a method for preparing a thermal insulation fabric using polyurethane aerogel as the interlayer material. This method uses pentaerythritol, toluene diisocyanate, silicone softener, organic solvent, and catalyst as raw materials to prepare the polyurethane aerogel, wherein the molar ratio of pentaerythritol, toluene diisocyanate, and catalyst is 5-10:0.5-1:0.1-0.2. However, this prior art has significant technical defects: First, the prepared polyurethane aerogel has poor hydrolysis resistance and is prone to hydrolysis in humid environments, leading to performance degradation; second, the material has insufficient aging resistance and is prone to performance degradation during long-term use; third, its flame retardant properties are limited, making it difficult to meet stringent fire safety requirements; and finally, its thermal conductivity is relatively high, and the thermal insulation effect needs further improvement. Summary of the Invention

[0004] In view of this, the present invention proposes a hydrolysis-resistant polyurethane resin aerogel and its preparation method to solve the problem of poor hydrolysis resistance and flame retardant properties of polyurethane aerogels in the prior art.

[0005] The technical solution of the present invention is achieved as follows: The present invention provides a hydrolysis-resistant polyurethane resin aerogel, which, by weight, comprises the following components: 60-80 parts of polyether polyol, 30-50 parts of polyester polyol, 10-15 parts of modified silica, 20-30 parts of isocyanate, 0.5-2 parts of dispersant and 0.5-1 parts of catalyst.

[0006] This invention constructs a polyurethane matrix using polyether polyols, polyester polyols, and isocyanates, and introduces modified silica fillers. The resulting hydrolysis-resistant polyurethane resin aerogel exhibits excellent comprehensive properties: the amino groups retained on the surface of the modified silica can chemically react with isocyanates during polyurethane preparation to form urethane bonds, achieving chemical bonding between the filler and the polyurethane matrix. Compared to traditional physical mixing methods, this chemical bonding significantly improves the uniformity of filler dispersion in the matrix, eliminates interfacial defects, and enhances the interfacial bonding force between the filler and the matrix, thereby greatly improving the mechanical strength and durability of the material, while avoiding filler agglomeration, sedimentation, and migration. Furthermore, the fluorine-containing groups in the modified silica significantly improve the material's hydrolysis resistance, maintaining stable structure and performance even in humid environments; the boron nitride composite structure endows the material with good flame retardant properties, improving safety in use; the low thermal conductivity of silica combined with the porous structure of aerogel gives the material excellent thermal insulation performance; at the same time, the unique lightweight porous structure of aerogel not only reduces the material density but also maintains good mechanical strength, solving the technical problems of poor hydrolysis resistance and insufficient flame retardant properties of polyurethane aerogel in the prior art.

[0007] Based on the above technical solutions, the preferred method for preparing the modified silica is as follows: S1. Disperse silica in water, add boric acid and melamine, stir and react at 80-90℃ for 4-5 hours, and then dry and calcine to obtain composite silica; S2. 4,4,4-trifluoro-3-(trifluoromethyl)crotonic acid is dispersed in DMF, aminosilane coupling agent and p-toluenesulfonic acid are added, the temperature is raised to 100-120℃, and the reaction is carried out for 6-8 hours to obtain the modifier. S3. Disperse the composite silica in anhydrous ethanol, add a modifier and acetic acid, heat to 60-65℃, and react for 6-8 hours to obtain fluorine-containing composite silica. S4. Disperse fluorinated composite silica in anhydrous ethanol, add 6-amino-2-mercaptobenzothiazole and 2,2-dimethoxy-2-phenylacetophenone, and react under ultraviolet light at 20-25℃ for 1-2 hours to obtain the modified filler.

[0008] Specifically, in step S1, boron nitride is generated in situ on the surface of silica using boric acid and melamine. The introduction of boron nitride primarily imparts excellent flame-retardant properties to the material. Although boron nitride itself has a high thermal conductivity, its combination with silica, which has a low thermal conductivity, ensures that the prepared composite silica retains both flame-retardant properties and overall thermal insulation performance. In step S2, the carboxyl group of 4,4,4-trifluoro-3-(trifluoromethyl)crotonic acid undergoes an amidation reaction with the amino group of the aminosilane coupling agent under the catalysis of p-toluenesulfonic acid, forming a modifier molecule containing fluorinated alkyl chains, double bond structures, and silane groups. The fluorinated groups provide excellent hydrolysis resistance due to the high bond energy and low polarization of the CF bond, and the introduction of the double bond structure provides active sites for subsequent click reactions. In step S3, the silane groups in the modifier condense with the hydroxyl groups on the surface of the composite silica to achieve chemical bonding of the modifier on the composite silica surface. This not only improves the hydrolysis resistance of the filler but also enhances the compatibility between the filler and the polyurethane matrix. In step S4, amino and benzothiazole groups are introduced through a mercaptoene reaction. The introduction of the benzothiazole groups endows the material with excellent antioxidant and aging resistance properties, and its conjugated aromatic structure can effectively capture free radicals. The retention of the amino groups provides active sites for subsequent chemical reactions with the polyurethane matrix, thus achieving chemical bonding between the filler and the matrix. The above technical solution achieves the organic integration of boron nitride flame-retardant groups, fluorinated hydrolysis-resistant groups, benzothiazole aging-resistant groups, and amino reactive groups. The functional groups form a synergistic effect, jointly improving the comprehensive performance of the material. Among them, boron nitride mainly contributes to the flame-retardant performance, the silica matrix ensures the overall heat insulation effect, the combination of fluorinated groups and benzothiazole groups achieves dual protection against hydrolysis and aging, and the presence of amino groups ensures a strong chemical bond between the modified filler and the polyurethane matrix. The modified filler prepared in the end has multiple functions such as flame retardancy, heat insulation, hydrolysis resistance, and aging resistance.

[0009] Based on the above technical solutions, preferably, in step S1, the mass ratio of silicon dioxide, boric acid and melamine is 100:15-25:10-20.

[0010] Based on the above technical solutions, preferably, in step S1, the calcination atmosphere is a nitrogen atmosphere, the temperature is 800-1000℃, and the time is 4-6h.

[0011] Based on the above technical solutions, preferably, in step S2, the mass ratio of 4,4,4-trifluoro-3-(trifluoromethyl)crotonic acid, aminosilane coupling agent, and p-toluenesulfonic acid is 100:80-120:1-3, and the aminosilane coupling agent is one of γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, N-β-aminoethyl-γ-aminopropyltrimethoxysilane, and aminoethylaminopropyltrimethoxysilane.

[0012] Based on the above technical solutions, preferably, in step S3, the mass ratio of composite silica, modifier and acetic acid is 100:8-15:0.5-2.

[0013] Based on the above technical solutions, preferably, in step S4, the mass ratio of fluorinated composite silica, 6-amino-2-mercaptobenzothiazole and 2,2-dimethoxy-2-phenylacetophenone is 100:3-8:0.5-1.5.

[0014] Based on the above technical solutions, preferably, the isocyanate is hexamethylene diisocyanate, toluene diisocyanate, or isophorone diisocyanate.

[0015] Based on the above technical solutions, preferably, the dispersant is an ammonium polyacrylate dispersant, and the catalyst is dibutyltin dilaurate or stannous octoate.

[0016] Based on the above technical solutions, the preferred method includes the following steps: mixing polyether polyol, polyester polyol, modified silica and dispersant to obtain a first mixture; adding catalyst and isocyanate to the first mixture and stirring at 20-30℃ for 0.5-1h to obtain a wet gel; aging the wet gel at 40-50℃ for 12-24h, and then solvent replacement and vacuum drying to obtain a hydrolysis-resistant polyurethane resin aerogel.

[0017] The hydrolysis-resistant polyurethane resin aerogel and its preparation method of the present invention have the following advantages over the prior art: (1) By chemically bonding the amino groups on the surface of modified silica with isocyanates, the filler and the polyurethane matrix are bonded at the molecular level, which significantly improves the overall performance of the material. The amino groups on the surface of modified silica can react with isocyanates to chemically bond the filler to the polyurethane molecular chain. Compared with the traditional physical mixing method, this chemical bonding eliminates the interfacial defects between the filler and the matrix, improves the uniformity of filler dispersion, and enhances the interfacial bonding force, thereby significantly improving the mechanical strength and structural stability of the material. At the same time, the fluorine-containing groups, boron nitride composite structure and benzothiazole groups in the modified silica give the material excellent hydrolysis resistance, flame retardancy and aging resistance, respectively. Combined with the low thermal conductivity of silica and the porous structure of aerogel, a polyurethane resin aerogel with multiple functions such as heat insulation, hydrolysis resistance, flame retardancy and aging resistance is finally prepared.

[0018] (2) Modified silica achieves the orderly integration and synergistic effect of multifunctional groups. First, boron nitride is generated on the silica surface through the in-situ reaction of boric acid and melamine, which gives the material flame retardant properties. Then, the fluorine-containing modifier is chemically bonded to the silica surface through silane coupling agent, introducing hydrolysis-resistant fluorine-containing groups and achieving stable immobilization of fluorine-containing groups. Finally, benzothiazole groups are introduced through the thiol-ene click reaction initiated by ultraviolet light, which provides aging resistance. At the same time, the amino group is retained for subsequent chemical bonding with the polyurethane matrix. The entire modification process achieves the organic integration of flame retardant, hydrolysis-resistant, aging-resistant and reactive groups.

[0019] (3) By combining polyether polyol and polyester polyol, the balance between material flexibility and mechanical strength is optimized. Polyether polyol has good flexibility and low temperature performance, while polyester polyol provides high mechanical strength and chemical corrosion resistance. The combination of the two ensures both the flexibility of the aerogel and sufficient mechanical strength, avoiding the performance limitations of a single polyol system. This allows the prepared aerogel to maintain a lightweight porous structure while possessing good mechanical properties. Detailed Implementation

[0020] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0021] It should be noted that the polyether polyol was purchased from Guangzhou Kosite New Materials Co., Ltd., model PTMEG250; the polyester polyol was purchased from Hubei Maidehao Biotechnology Co., Ltd., model MDH; the ammonium polyacrylate dispersant was purchased from Xinyue New Materials (Guangdong) Co., Ltd., model BYK-154; and the silica was purchased from Lingshou County Wanzhu Mineral Products Co., Ltd., with a particle size of 300 mesh.

[0022] Example 1 This embodiment provides a hydrolysis-resistant polyurethane resin aerogel and its preparation method. By weight, it comprises the following components: 70 parts polyether polyol, 40 parts polyester polyol, 13 parts modified silica, 25 parts hexamethylene diisocyanate, 1 part ammonium polyacrylate dispersant, and 0.8 parts stannous octoate. The preparation method is as follows: Polyether polyol and polyester polyol were mixed evenly at room temperature, and modified silica and ammonium polyacrylate dispersant were added. The mixture was ultrasonically dispersed for 20 min to obtain the first mixture. Stannous octoate and hexamethylene diisocyanate were added to the first mixture and stirred at 25°C for 0.8 h to obtain a wet gel. The wet gel was poured into a mold and aged at 45°C for 18 h to complete the gelation. The gel was then solvent-replaced with acetone, soaked for 4 h each time, and the acetone was replaced 3 times. Finally, it was vacuum dried to obtain a hydrolysis-resistant polyurethane resin aerogel.

[0023] The preparation method of modified silica is as follows: S1. Disperse 100g of silica in 1000ml of deionized water and ultrasonically disperse until uniform. Add 20g of boric acid and 15g of melamine. Stir and react at 85℃ for 4.5h. After the reaction is complete, filter, wash and dry to obtain a mixture. Place the mixture in a tube furnace and calcine at 900℃ for 5h under a nitrogen atmosphere. Allow it to cool naturally to room temperature to obtain composite silica. S2. 100g of 4,4,4-trifluoro-3-(trifluoromethyl)crotonic acid was dispersed in 1000ml of DMF, 100g of γ-aminopropyltriethoxysilane and 2g of p-toluenesulfonic acid were added, the temperature was raised to 110℃ and the reaction was carried out for 7h. After the reaction was completed, the reaction solution was poured into a large amount of ice water to precipitate the product, which was collected by filtration, washed and dried to obtain the modifier. S3. Disperse 100g of composite silica in 1000ml of anhydrous ethanol, ultrasonically disperse it evenly, add 11.5g of modifier, 1g of acetic acid and 5ml of deionized water, heat to 63℃, react for 7h, centrifuge after the reaction is completed, wash and dry to obtain fluorine-containing composite silica. S4. Disperse 100g of fluorinated composite silica in 1000ml of anhydrous ethanol and ultrasonically disperse until uniform. Add 5.5g of 6-amino-2-mercaptobenzothiazole and 1.0g of 2,2-dimethoxy-2-phenylacetophenone. React at 23℃ for 1.5h under ultraviolet light irradiation (365nm, power 100W). After the reaction is completed, centrifuge, wash and dry to obtain the modified filler.

[0024] Example 2 This embodiment provides a hydrolysis-resistant polyurethane resin aerogel and its preparation method. By weight, it comprises the following components: 60 parts polyether polyol, 30 parts polyester polyol, 10 parts modified silica, 20 parts hexamethylene diisocyanate, 0.5 parts ammonium polyacrylate dispersant, and 0.5 parts stannous octoate. The preparation method is as follows: Polyether polyol and polyester polyol were mixed evenly at room temperature, and modified silica and ammonium polyacrylate dispersant were added. The mixture was ultrasonically dispersed for 20 min to obtain the first mixture. Stannous octoate and hexamethylene diisocyanate were added to the first mixture and stirred at 20°C for 1 h to obtain a wet gel. The wet gel was poured into a mold and aged at 40°C for 24 h to complete the gelation. The gel was then solvent-replaced with acetone, soaked for 4 h each time, and the acetone was replaced 3 times. Finally, it was vacuum dried to obtain a hydrolysis-resistant polyurethane resin aerogel.

[0025] The preparation method of modified silica is as follows: S1. Disperse 100g of silica in 1000ml of deionized water and ultrasonically disperse until uniform. Add 15g of boric acid and 10g of melamine. Stir and react at 80℃ for 5h. After the reaction is complete, filter, wash and dry to obtain a mixture. Place the mixture in a tube furnace and calcine at 800℃ for 6h under a nitrogen atmosphere. Allow it to cool naturally to room temperature to obtain composite silica. S2. 100g of 4,4,4-trifluoro-3-(trifluoromethyl)crotonic acid was dispersed in 1000ml of DMF, 80g of γ-aminopropyltriethoxysilane and 1g of p-toluenesulfonic acid were added, the temperature was raised to 100℃ and the reaction was carried out for 8h. After the reaction was completed, the reaction solution was poured into a large amount of ice water to precipitate the product, which was then collected by filtration, washed and dried to obtain the modifier. S3. Disperse 100g of composite silica in 1000ml of anhydrous ethanol, ultrasonically disperse until uniform, add 8g of modifier, 0.5g of acetic acid and 5ml of deionized water, heat to 60℃, react for 8h, centrifuge after reaction, wash and dry to obtain fluorine-containing composite silica. S4. Disperse 100g of fluorinated composite silica in 1000ml of anhydrous ethanol and ultrasonically disperse it evenly. Add 3g of 6-amino-2-mercaptobenzothiazole and 0.5g of 2,2-dimethoxy-2-phenylacetophenone. Under ultraviolet light irradiation (365nm, power 100W), react at 20℃ for 2h. After the reaction is completed, centrifuge, wash and dry to obtain the modified filler.

[0026] Example 3 This embodiment provides a hydrolysis-resistant polyurethane resin aerogel and its preparation method. By weight, it comprises the following components: 80 parts polyether polyol, 50 parts polyester polyol, 15 parts modified silica, 30 parts hexamethylene diisocyanate, 2 parts ammonium polyacrylate dispersant, and 1 part stannous octoate. The preparation method is as follows: Polyether polyol and polyester polyol were mixed evenly at room temperature, and modified silica and ammonium polyacrylate dispersant were added. The mixture was ultrasonically dispersed for 20 min to obtain the first mixture. Stannous octoate and hexamethylene diisocyanate were added to the first mixture and stirred at 30°C for 0.5 h to obtain a wet gel. The wet gel was poured into a mold and aged at 50°C for 12 h to complete the gelation. The gel was then solvent-replaced with acetone, soaked for 4 h each time, and the acetone was replaced 3 times. Finally, it was vacuum dried to obtain a hydrolysis-resistant polyurethane resin aerogel.

[0027] The preparation method of modified silica is as follows: S1. Disperse 100g of silica in 1000ml of deionized water and ultrasonically disperse until uniform. Add 25g of boric acid and 20g of melamine. Stir and react at 90℃ for 4h. After the reaction is complete, filter, wash and dry to obtain a mixture. Place the mixture in a tube furnace and calcine at 1000℃ for 4h under a nitrogen atmosphere. Allow it to cool naturally to room temperature to obtain composite silica. S2. 100g of 4,4,4-trifluoro-3-(trifluoromethyl)crotonic acid was dispersed in 1000ml of DMF, 120g of γ-aminopropyltriethoxysilane and 3g of p-toluenesulfonic acid were added, the temperature was raised to 120℃ and the reaction was carried out for 6h. After the reaction was completed, the reaction solution was poured into a large amount of ice water to precipitate the product, which was collected by filtration, washed and dried to obtain the modifier. S3. Disperse 100g of composite silica in 1000ml of anhydrous ethanol, ultrasonically disperse it evenly, add 15g of modifier, 2g of acetic acid and 5ml of deionized water, heat to 65℃, react for 6h, centrifuge after the reaction is completed, wash and dry to obtain fluorine-containing composite silica. S4. Disperse 100g of fluorinated composite silica in 1000ml of anhydrous ethanol and ultrasonically disperse it evenly. Add 8g of 6-amino-2-mercaptobenzothiazole and 1.5g of 2,2-dimethoxy-2-phenylacetophenone. Under ultraviolet light irradiation (365nm, power 100W), react at 25℃ for 1h. After the reaction is completed, centrifuge, wash and dry to obtain the modified filler.

[0028] Comparative Example 1 This comparative example provides a hydrolysis-resistant polyurethane resin aerogel and its preparation method. By weight, it comprises the following components: 70 parts polyether polyol, 40 parts polyester polyol, 13 parts modified silica, 25 parts hexamethylene diisocyanate, 1 part ammonium polyacrylate dispersant, and 0.8 parts stannous octoate. The preparation method is the same as in Example 1, except that the modified silica is not grafted with 6-amino-2-mercaptobenzothiazole, as detailed below: The preparation method of modified silica is as follows: S1. Disperse 100g of silica in 1000ml of deionized water and ultrasonically disperse until uniform. Add 20g of boric acid and 15g of melamine. Stir and react at 85℃ for 4.5h. After the reaction is complete, filter, wash and dry to obtain a mixture. Place the mixture in a tube furnace and calcine at 900℃ for 5h under a nitrogen atmosphere. Allow it to cool naturally to room temperature to obtain composite silica. S2. 100g of 4,4,4-trifluoro-3-(trifluoromethyl)crotonic acid was dispersed in 1000ml of DMF, 100g of γ-aminopropyltriethoxysilane and 2g of p-toluenesulfonic acid were added, the temperature was raised to 110℃ and the reaction was carried out for 7h. After the reaction was completed, the reaction solution was poured into a large amount of ice water to precipitate the product, which was collected by filtration, washed and dried to obtain the modifier. S3. Disperse 100g of composite silica in 1000ml of anhydrous ethanol and ultrasonically disperse it evenly. Add 11.5g of modifier, 1g of acetic acid and 5ml of deionized water, heat to 63℃ and react for 7h. After the reaction is completed, centrifuge and separate the silica. After washing and drying, the modified silica is obtained.

[0029] Comparative Example 2 This comparative example provides a hydrolysis-resistant polyurethane resin aerogel and its preparation method. By weight, it comprises the following components: 70 parts polyether polyol, 40 parts polyester polyol, 13 parts modified silica, 25 parts hexamethylene diisocyanate, 1 part ammonium polyacrylate dispersant, and 0.8 parts stannous octoate. The preparation method is the same as in Example 1, except that the modified silica is not loaded with boron nitride, as detailed below: The preparation method of modified silica is as follows: S1. Disperse 100g of 4,4,4-trifluoro-3-(trifluoromethyl)crotonic acid in 1000ml of DMF, add 100g of γ-aminopropyltriethoxysilane and 2g of p-toluenesulfonic acid, heat to 110℃ and react for 7h. After the reaction is completed, pour the reaction solution into a large amount of ice water to precipitate the product, filter and collect it, wash and dry it to obtain the modifier. S2. Disperse 100g of silica in 1000ml of anhydrous ethanol and ultrasonically disperse it evenly. Add 11.5g of modifier, 1g of acetic acid and 5ml of deionized water. Heat to 63℃ and react for 7h. After the reaction is completed, centrifuge and separate the silica. After washing and drying, fluorine-containing composite silica is obtained. S3. Disperse 100g of fluorinated composite silica in 1000ml of anhydrous ethanol and ultrasonically disperse it evenly. Add 5.5g of 6-amino-2-mercaptobenzothiazole and 1.0g of 2,2-dimethoxy-2-phenylacetophenone. Under ultraviolet light irradiation (365nm, power 100W), react at 23℃ for 1.5h. After the reaction is completed, centrifuge, wash and dry to obtain the modified filler.

[0030] Comparative Example 3 This comparative example provides a hydrolysis-resistant polyurethane resin aerogel and its preparation method. By weight, it comprises the following components: 70 parts polyether polyol, 40 parts polyester polyol, 13 parts modified silica, 25 parts hexamethylene diisocyanate, 1 part ammonium polyacrylate dispersant, and 0.8 parts stannous octoate. The preparation method is the same as in Example 1, except that: The preparation method of modified silica is as follows: S1. Disperse 100g of silica in 1000ml of deionized water and ultrasonically disperse until uniform. Add 20g of boric acid and 15g of melamine. Stir and react at 85℃ for 4.5h. After the reaction is complete, filter, wash and dry to obtain a mixture. Place the mixture in a tube furnace and calcine at 900℃ for 5h under a nitrogen atmosphere. Allow it to cool naturally to room temperature to obtain composite silica. S2. Disperse 100g of composite silica in 1000ml of anhydrous ethanol and ultrasonically disperse it evenly. Add 11.5g of γ-aminopropyltriethoxysilane, 1g of acetic acid and 5ml of deionized water. Heat to 63℃ and react for 7h. After the reaction is completed, centrifuge and separate the silica. After washing and drying, obtain aminated composite silica. S3. Disperse 100g of aminated composite silica in 1000ml of anhydrous ethanol and ultrasonically disperse it evenly. Add 5.5g of 6-amino-2-mercaptobenzothiazole and stir for 1.5h. After mixing, centrifuge, wash and dry to obtain the modified filler.

[0031] Comparative Example 4 This comparative example provides a hydrolysis-resistant polyurethane resin aerogel and its preparation method. By weight, it comprises the following components: 70 parts polyether polyol, 40 parts polyester polyol, 13 parts modified silica, 25 parts hexamethylene diisocyanate, 1 part ammonium polyacrylate dispersant, and 0.8 parts stannous octoate. The preparation method is the same as in Example 1, except that: The preparation method of modified silica is as follows: S1. Disperse 100g of silica in 1000ml of deionized water and ultrasonically disperse until uniform. Add 20g of boric acid and 15g of melamine. Stir and react at 85℃ for 4.5h. After the reaction is complete, filter, wash and dry to obtain a mixture. Place the mixture in a tube furnace and calcine at 900℃ for 5h under a nitrogen atmosphere. Allow it to cool naturally to room temperature to obtain composite silica. S2. Disperse 100g of composite silica in 1000ml of anhydrous ethanol and ultrasonically disperse it evenly. Add 11.5g of 4,4,4-trifluoro-3-(trifluoromethyl)crotonic acid and 5.5g of 6-amino-2-mercaptobenzothiazole. Place the mixture in a high-speed mixer and mix at high speed for 30min at room temperature. Then pass it through a 200-mesh sieve to obtain the modified filler.

[0032] Performance testing The polyurethane resin aerogels prepared in the examples and comparative examples were subjected to performance testing. The test indicators included thermal conductivity, flame retardancy, aging resistance, and hydrolysis resistance. Thermal conductivity was tested according to standard GB / T10294-2008, and tensile strength was tested according to standard GB / T6344-2008. Hydrolysis resistance was tested by aging the polyurethane resin aerogels at 70℃ and 95% relative humidity for 168 hours, and the tensile strength retention rate before and after the test was measured as the ratio of tensile strength before and after the test. Flame retardancy was tested according to ASTM D2863-17. Aging resistance was tested by placing the samples in a xenon aging chamber, irradiating ultraviolet light at 290~340nm, with a rated power of 1.8kW, a temperature of (60±3)℃, a relative humidity of (50±5)%, and an ultraviolet aging time of 200 hours, and comparing the tensile strength retention rate before and after aging as the ratio of tensile strength after aging to tensile strength before aging. The test results are shown in Table 1.

[0033] Table 1 Performance Testing As shown in Table 1, the hydrolysis-resistant polyurethane resin aerogel prepared by the technical solution of the present invention not only has good thermal insulation and flame retardant properties, but also has good hydrolysis resistance and aging resistance.

[0034] 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 hydrolysis-resistant polyurethane resin aerogel, characterized in that: By weight, it includes the following components: 60-80 parts of polyether polyol, 30-50 parts of polyester polyol, 10-15 parts of modified silica, 20-30 parts of isocyanate, 0.5-2 parts of dispersant and 0.5-1 parts of catalyst.

2. The hydrolysis-resistant polyurethane resin aerogel as described in claim 1, characterized in that: The modified silica is prepared as follows: S1. Disperse silica in water, add boric acid and melamine, stir and react at 80-90℃ for 4-5 hours, and then dry and calcine to obtain composite silica; S2. 4,4,4-trifluoro-3-(trifluoromethyl)crotonic acid is dispersed in DMF, aminosilane coupling agent and p-toluenesulfonic acid are added, the temperature is raised to 100-120℃, and the reaction is carried out for 6-8 hours to obtain the modifier. S3. Disperse the composite silica in anhydrous ethanol, add a modifier and acetic acid, heat to 60-65℃, and react for 6-8 hours to obtain fluorine-containing composite silica. S4. Disperse fluorinated composite silica in anhydrous ethanol, add 6-amino-2-mercaptobenzothiazole and 2,2-dimethoxy-2-phenylacetophenone, and react under ultraviolet light at 20-25℃ for 1-2 hours to obtain the modified filler.

3. The hydrolysis-resistant polyurethane resin aerogel as described in claim 2, characterized in that: In step S1, the mass ratio of silica, boric acid and melamine is 100:15-25:10-20.

4. The hydrolysis-resistant polyurethane resin aerogel as described in claim 2, characterized in that: In step S1, the calcination atmosphere is nitrogen, the temperature is 800-1000℃, and the time is 4-6h.

5. The hydrolysis-resistant polyurethane resin aerogel as described in claim 2, characterized in that: In step S2, the mass ratio of 4,4,4-trifluoro-3-(trifluoromethyl)crotonic acid, aminosilane coupling agent, and p-toluenesulfonic acid is 100:80-120:1-3, and the aminosilane coupling agent is one of γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, N-β-aminoethyl-γ-aminopropyltrimethoxysilane, and aminoethylaminopropyltrimethoxysilane.

6. The hydrolysis-resistant polyurethane resin aerogel as described in claim 2, characterized in that: In step S3, the mass ratio of composite silica, modifier and acetic acid is 100:8-15:0.5-2.

7. The hydrolysis-resistant polyurethane resin aerogel as described in claim 2, characterized in that: In step S4, the mass ratio of fluorinated composite silica, 6-amino-2-mercaptobenzothiazole and 2,2-dimethoxy-2-phenylacetophenone is 100:3-8:0.5-1.

5.

8. The hydrolysis-resistant polyurethane resin aerogel as described in claim 1, characterized in that: The isocyanate is hexamethylene diisocyanate, toluene diisocyanate, or isophorone diisocyanate.

9. The hydrolysis-resistant polyurethane resin aerogel as described in claim 1, characterized in that: The dispersant is ammonium polyacrylate dispersant, and the catalyst is dibutyltin dilaurate or stannous octoate.

10. A method for preparing a hydrolysis-resistant polyurethane resin aerogel according to any one of claims 1-9, characterized in that: Includes the following steps: Polyether polyol, polyester polyol, modified silica and dispersant are mixed to obtain a first mixture; catalyst and isocyanate are added to the first mixture and stirred at 20-30℃ for 0.5-1h to obtain a wet gel; the wet gel is aged at 40-50℃ for 12-24h, and then subjected to solvent replacement and vacuum drying to obtain a hydrolysis-resistant polyurethane resin aerogel.

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