Aerogel blending modified organic silicon resin as well as preparation method and application thereof

Abstract

The invention relates to the technical field of composite materials, and particularly discloses aerogel blending modified organic silicon resin as well as a preparation method and application thereof. The aerogel blending modified organic silicon resin provided by the invention is firm in interface bonding, has good mechanical property, heat insulation property and intrinsic flame retardance, and solves the problems that a traditional aerogel / organic silicon resin composite material is weak in interface, contradictory in mechanical property and heat insulation property, insufficient in flame retardance and easy to lose efficacy at high temperature. Meanwhile, the preparation method of the aerogel blending modified organic silicon resin, provided by the invention, is mild in reaction condition, simple and convenient to operate and easy to control, does not need special complex equipment, and is suitable for large-scale production.

Description

Technical Field

[0001] This invention relates to the field of composite materials technology, specifically disclosing an aerogel-modified organosilicon resin, its preparation method, and its applications. Background Technology

[0002] With the development of aerospace, new energy vehicles, and high-end electronic devices, the application of thermal insulation materials often faces challenges such as temperature fluctuations, mechanical stress, and environmental corrosion. This necessitates that thermal insulation materials possess thermal insulation, mechanical support, reliable flame retardancy, and long-term service stability. Organosilicon resins, due to their resistance to high and low temperatures, electrical insulation, and chemical stability, are considered ideal high-performance polymer matrices; while aerogels, especially silica aerogels, are considered the ultimate thermal insulation material due to their ultra-low thermal conductivity resulting from their nanoporous structure. Theoretically, combining these two materials can achieve complementary advantages, yielding thermal insulation materials with excellent overall performance.

[0003] However, in existing aerogel / silicone resin composites, the inert polydimethylsiloxane-based silicone resin and the inorganic aerogel skeleton rich in hydroxyl groups are only bonded by weak van der Waals forces in traditional physical blending or simple impregnation processes. This makes them prone to microcracks under thermal or mechanical stress, leading to material delamination and pulverization, severely affecting structural load-bearing capacity and long-term stability. Furthermore, to improve mechanical properties, current technologies require increasing the resin filler content, which disrupts the nanoporous structure of the aerogel, thereby increasing the solid-state thermal conductivity. In addition, both pure silica aerogel and conventional silicone resins are flammable or combustible materials. While adding flame retardants can improve flame retardancy, it can lead to decreased interfacial compatibility and mechanical properties, or cause the insulation material to decompose and fail at high temperatures. Therefore, providing an aerogel / silicone resin composite material with good interfacial bonding, flame retardancy, thermal insulation, and mechanical properties has become a pressing technical problem to be solved in this field. Summary of the Invention

[0004] To address the problems of poor interfacial bonding performance, the inability to simultaneously improve mechanical and thermal insulation properties, insufficient flame retardancy, and easy failure at high temperatures in existing aerogel / silicone resin composite materials, this invention provides an aerogel-modified silicone resin, its preparation method, and its applications. The aerogel-modified silicone resin provided by this invention exhibits excellent interfacial bonding capabilities, along with good strength, toughness, and flame retardancy, meeting the requirements of aerospace, new energy vehicles, and high-end electronic devices for thermal insulation materials that combine high strength, high toughness, high thermal insulation, high flame retardancy, and long-term service stability.

[0005] The present invention provides an aerogel-modified organosilicon resin, its preparation method, and its application, using the following technical solution: The first aspect of this invention provides a method for preparing an aerogel-modified organosilicon resin, comprising the following steps: S1. Melamine polyphosphate and dilute hydrochloric acid are mixed and then filtered, washed and dried in sequence, and then dispersed in an ethanol aqueous solution to obtain a suspension. S2. The suspension, γ-(2,3-epoxypropoxy)propyltrimethoxysilane and 3-aminopropyltriethoxysilane are mixed and refluxed at 70-80°C to obtain surface-functionalized melamine polyphosphate. S3. After mixing the surface-functionalized melamine polyphosphate with the nanocellulose solution, tetraethyl orthosilicate and ethanol are added, the pH is adjusted to 1.5-2.5, and the mixture is stirred at 35-45℃. Then the pH is adjusted to 6.5-7.5, and the mixture is allowed to stand and age at 35-45℃ to obtain a composite wet gel. S4. The composite wet gel is immersed in anhydrous ethanol, and solvent exchange and drying are performed sequentially to obtain ternary composite aerogel. S5. The ternary composite aerogel, xylene, epoxy-modified organosilicon resin and 2-ethyl-4-methylimidazole are mixed and poured into a polytetrafluoroethylene mold for vacuum degassing, programmed temperature rise curing, and demolding after natural cooling to obtain aerogel blend modified organosilicon resin.

[0006] In S1 of this invention, dilute hydrochloric acid can activate the surface of melamine polyphosphate, remove impurities and expose active sites. At the same time, the suspension formed by dispersing the treated melamine polyphosphate in an ethanol aqueous solution can provide a uniform reaction environment for subsequent reactions and improve reaction efficiency.

[0007] In S2 of this invention, γ-(2,3-epoxypropoxy)propyltrimethoxysilane and 3-aminopropyltriethoxysilane are used as silane coupling agents. Their epoxy groups and amino groups can undergo ring-opening reactions and be grafted onto the surface of melamine polyphosphate, thereby achieving surface functionalization of melamine polyphosphate.

[0008] In S3 of this invention, the surface-functionalized melamine polyphosphate is mixed with the nanocellulose solution to form a stable dispersion system. At the same time, tetraethyl orthosilicate undergoes a hydrolysis reaction under acidic conditions, and its hydrolysis products undergo a condensation reaction with nanocellulose and surface-functionalized melamine polyphosphate to form a stable and rigid silica network rich in active hydroxyl groups.

[0009] In S4 of this invention, anhydrous ethanol is used as a solvent to replace the residual water and other impurities in the composite wet gel. Multiple solvent exchanges can ensure that the impurities inside the wet gel are fully removed, and the drying process can remove the residual anhydrous ethanol and retain the porous structure of the wet gel.

[0010] In S5 of this invention, xylene is used as a dispersion medium to uniformly disperse the ternary composite aerogel in the epoxy-modified organosilicon resin. 2-Ethyl-4-methylimidazole is used as a catalyst to catalyze the ring-opening addition reaction between epoxy groups and hydroxyl groups. At the same time, vacuum degassing can remove air bubbles in the mixed slurry, and finally aerogel blended modified organosilicon resin with good comprehensive performance is prepared.

[0011] More preferably, the melamine polyphosphate has the structural formula shown in Formula I.

[0012]

[0013] Formula I

[0014] Preferably, in S1, the mass-to-volume ratio of melamine polyphosphate to dilute hydrochloric acid is 1g:(8-12)mL, and the concentration of the dilute hydrochloric acid is 0.75-1.25mol / L.

[0015] Preferably, in S1, the mixing is carried out under stirring conditions, with a stirring rate of 300-800 r / min, a temperature of 50-70℃, and a time of 1.5-2.5 h.

[0016] Preferably, in S1, the drying is vacuum drying at a temperature of 75-85°C for 10-14 hours.

[0017] Preferably, in S1, the mass-to-volume ratio of the melamine polyphosphate to the ethanol aqueous solution is 1 g: (5-10) mL, and the volume concentration of the ethanol aqueous solution is 70%-80%.

[0018] Preferably, in S2, the mass-to-volume ratio of melamine polyphosphate, γ-(2,3-epoxypropoxy)propyltrimethoxysilane and 3-aminopropyltriethoxysilane in the suspension is 1 g: (0.2-0.4) mL: (0.1-0.2) mL.

[0019] Preferably, in S2, the reflux reaction time is 6-10 hours.

[0020] Preferably, in step S2, after the reflux reaction is completed, the reflux product is vacuum dried to obtain the surface-functionalized melamine polyphosphate. The vacuum drying temperature is 70-90°C and the time is 20-28 hours.

[0021] Preferably, in S3, the mass-to-volume ratio of the surface-functionalized melamine polyphosphate to the nanocellulose solution is 1 g: (15-25) mL, and the mass concentration of the nanocellulose solution is 0.5-1.5 wt%.

[0022] Preferably, in S3, the mass-to-volume ratio of the surface-functionalized melamine polyphosphate, tetraethyl orthosilicate, and ethanol is 1 g: (3-5) g: (3-5) mL.

[0023] Preferably, in step S3, the stirring reaction time is 3-5 hours.

[0024] Preferably, in S3, the settling and aging time is 20-28 hours.

[0025] Preferably, in S4, the mass-to-volume ratio of the composite wet gel to anhydrous ethanol is 1 g: (10-15) mL.

[0026] Preferably, in step S4, the solvent exchange specifically includes the following steps: The composite wet gel was soaked in anhydrous ethanol, and the anhydrous ethanol was replaced every 6 hours for a total of 5 times, with the same amount of anhydrous ethanol used each time.

[0027] Preferably, in step S4, the drying process specifically includes the following steps: The solvent-exchanged composite wet gel was dried at 40-60℃ for 10-14 hours, and then dried at 100-120℃ for 3-5 hours to obtain a ternary composite aerogel.

[0028] Preferably, in step S4, after drying, the dried product is further ball-milled at a speed of 400-500 r / min for 10-30 min to obtain the ternary composite aerogel.

[0029] Preferably, in S5, the mass-to-volume ratio of the ternary composite aerogel, xylene, epoxy-modified organosilicon resin and 2-ethyl-4-methylimidazole is 1g:(20-25)mL:(5-6)g:(0.03-0.05)g.

[0030] Preferably, in step S5, the mixing is carried out under stirring conditions, with a rotation speed of 4000-6000 r / min and a time of 0.25-0.75 h.

[0031] Preferably, in step S5, the temperature of the vacuum degassing is 70-90°C and the time is 0.5-1.5h.

[0032] Preferably, in S5, the programmed temperature curing includes the following steps: first, the mold is kept at 95-105℃ for 1-3 hours, and then kept at 145-155℃ for 3-5 hours.

[0033] Preferably, in step S5, the preparation method of the epoxy-modified organosilicon resin includes the following steps: A mixture of dihydroxyl-terminated polydimethylsiloxane, phenyltrimethoxysilane, diphenyldimethoxysilane, acetic acid, dioxane, and water was subjected to hydrolysis and condensation reactions at 70-90℃. Then, γ-(2,3-epoxypropoxy)propyltrimethoxysilane was added, and a condensation reaction was carried out at 80-90℃ to obtain an epoxy-modified organosilicon resin.

[0034] In this invention, acetic acid is used as a catalyst, dioxane as a dispersion solvent, and water as a necessary medium for the hydrolysis reaction. Dihydroxyl-terminated polydimethylsiloxane, phenyltrimethoxysilane, and diphenyldimethoxysilane are used as reactants. During the hydrolysis and polycondensation reactions, a resin precursor with a stable cross-linked structure is generated, exhibiting good rigidity and chemical stability. Simultaneously, γ-(2,3-epoxypropoxy)propyltrimethoxysilane serves as a highly reactive epoxy group introducer. Its molecular structure contains epoxy functional groups and alkoxy groups, which possess dual reactivity. During the polycondensation reaction, it can undergo polycondensation with the hydroxyl groups remaining on the surface of the resin precursor via alkoxy groups, achieving chemical bonding between molecular chains. This grafts a large number of highly reactive epoxy groups onto the resin molecular chains, further optimizing the cross-linking density and molecular structure regularity of the resin, ultimately yielding an epoxy-modified organosilicon resin with excellent matrix properties and high reactivity.

[0035] More preferably, the structural formula of the double-hydroxyl-terminated polydimethylsiloxane is shown in Formula II, where m is the degree of polymerization of the polydimethylsiloxane, which is an integer from 20 to 100.

[0036]

[0037] Formula II

[0038] More preferably, the number-average molecular weight of the hydroxyl-terminated polydimethylsiloxane is 1900-2100.

[0039] Preferably, the mass-to-volume ratio of the dihydroxyl-terminated polydimethylsiloxane, phenyltrimethoxysilane, diphenyldimethoxysilane, acetic acid, dioxane, and water is 1 g : (0.3-0.4) g : (0.15-0.25) g : (0.0075-0.0125) g : (0.5-1.5) mL : (0.15-0.25) mL.

[0040] Preferably, the mass ratio of the dihydroxyl-terminated polydimethylsiloxane to γ-(2,3-epoxypropoxy)propyltrimethoxysilane is 1 g: (0.15-0.35) g.

[0041] Preferably, the hydrolysis and polycondensation reaction takes 3-5 hours.

[0042] Preferably, the polycondensation reaction takes 5-7 hours.

[0043] The second aspect of the present invention provides an aerogel-modified organosilicon resin, which is prepared by the aerogel-modified organosilicon resin preparation method described in the foregoing scheme.

[0044] The aerogel-modified silicone resin provided by this invention uses melamine polyphosphate as the flame-retardant functional raw material. It is grafted with a bissilane coupling agent of γ-(2,3-epoxypropoxy)propyltrimethoxysilane and 3-aminopropyltriethoxysilane to form a functionalized product with a surface rich in active groups such as hydroxyl and silanol groups, providing sufficient anchoring sites for subsequent chemical bonding. The phosphorus and nitrogen elements in the resin impart an intrinsic flame-retardant basis to the material. Simultaneously, the aerogel-modified silicone resin provided by this invention uses nanocellulose as the mechanical reinforcing raw material. Its natural nanofiber network structure provides the skeleton with good toughness and stress dispersion ability, enabling the construction of ternary composite aerogels with good mechanical properties and porous structures with other raw materials. Furthermore, the epoxy-modified silicone resin allows it to undergo ring-opening addition reactions with the multiple active hydroxyl groups on the aerogel surface, forming stable covalent ether bonds, replacing the weak van der Waals forces of traditional physical blending, thus solving the problem of poor interfacial bonding. The aerogel-modified organosilicon resin provided by this invention has good interfacial bonding performance, mechanical properties, flame retardant properties and thermal stability, and is suitable for the needs of thermal insulation materials in aerospace, new energy vehicles or high-end electronic devices.

[0045] The third aspect of the present invention provides the application of the aerogel-modified organosilicon resin described in the foregoing scheme in thermal insulation materials.

[0046] In summary, this invention provides an aerogel-modified organosilicon resin that achieves strong interfacial bonding through covalent bonding, simultaneously optimizing mechanical, thermal insulation, and flame retardant properties. This solves the problems of weak interfacial bonding, contradictory mechanical and thermal insulation properties, insufficient flame retardancy, and easy failure at high temperatures in traditional composite materials.

[0047] Meanwhile, this invention provides a method for preparing this aerogel-modified organosilicon resin. The method has mild reaction conditions, is easy to operate, requires no special or complex equipment, has good repeatability, and is suitable for large-scale production.

[0048] In addition, the aerogel-modified organosilicon resin described in this invention can be used as a core material in the preparation of thermal insulation materials. Detailed Implementation

[0049] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are merely one embodiment of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0050] Example 1

[0051] This embodiment provides a method for preparing aerogel-modified organosilicon resin, specifically including the following: The preparation method of the aerogel-modified organosilicon resin includes the following steps: S1. Mix 10g of melamine polyphosphate and 80mL of 0.75mol / L dilute hydrochloric acid at 50℃ and 300r / min for 1.5h, filter, wash, and then vacuum dry at 75℃ for 10-14h. Then disperse in 50mL of 70% ethanol aqueous solution to obtain a suspension. S2. The suspension, 2 mL of γ-(2,3-epoxypropoxy)propyltrimethoxysilane and 1 mL of 3-aminopropyltriethoxysilane were mixed and refluxed at 70 °C for 6 h. The reflux product was then vacuum dried at 70 °C for 20 h to obtain the surface-functionalized melamine polyphosphate. S3. Mix 10g of the surface-functionalized melamine polyphosphate with 150mL of 0.5wt% nanocellulose solution, add 30g of tetraethyl orthosilicate and 30mL of ethanol, adjust the pH to 1.5, stir and react at 35℃ for 3h, then adjust the pH to 6.5, and let stand at 35℃ for 20h to obtain composite wet gel. S4. Soak 10g of the composite wet gel in 100mL of anhydrous ethanol, and replace the anhydrous ethanol every 6 hours for a total of 5 times. The amount of anhydrous ethanol used each time is the same. Dry the composite wet gel after solvent exchange at 40℃ for 10 hours, then dry it at 100℃ for 3 hours. Then ball mill the dried product at 400r / min for 10 minutes to obtain ternary composite aerogel. S5. Mix 10g of the ternary composite aerogel, 200mL of xylene, 50g of epoxy-modified organosilicon resin and 0.3g of 2-ethyl-4-methylimidazole at 4000r / min for 0.25h, pour the mixture into a polytetrafluoroethylene mold and degas under vacuum at 70℃ for 0.5h. Then, place the mold at 95℃ for 1h and then at 145℃ for 3h. After natural cooling, demold to obtain aerogel-modified organosilicon resin.

[0052] The preparation method of the epoxy-modified organosilicon resin includes the following steps: 10g of hydroxyl-terminated polydimethylsiloxane, 3g of phenyltrimethoxysilane, 1.5g of diphenyldimethoxysilane, 0.075g of acetic acid, 5mL of dioxane, and 1.5mL of water were mixed and subjected to hydrolysis and condensation reaction at 70℃ for 3h. Then, 1.5g of γ-(2,3-epoxypropoxy)propyltrimethoxysilane was added, and condensation reaction was carried out at 80℃ for 5h to obtain epoxy-modified organosilicon resin.

[0053] Example 2

[0054] This embodiment provides a method for preparing aerogel-modified organosilicon resin, specifically including the following: The preparation method of the aerogel-modified organosilicon resin includes the following steps: S1. Mix 10g of melamine polyphosphate and 120mL of 1.25mol / L dilute hydrochloric acid at 70℃ and 800r / min for 2.5h, filter, wash, and then vacuum dry at 75-85℃ for 14h. Then disperse in 100mL of 80% ethanol aqueous solution to obtain a suspension. S2. The suspension, 4 mL of γ-(2,3-epoxypropoxy)propyltrimethoxysilane and 2 mL of 3-aminopropyltriethoxysilane were mixed and refluxed at 80 °C for 10 h. The reflux product was then vacuum dried at 90 °C for 28 h to obtain the surface-functionalized melamine polyphosphate. S3. Mix 10g of the surface-functionalized melamine polyphosphate with 250mL of 1.5wt% nanocellulose solution, add 50g of tetraethyl orthosilicate and 50mL of ethanol, adjust the pH to 2.5, stir and react at 45℃ for 5h, then adjust the pH to 7.5, and let stand at 45℃ for 28h to obtain composite wet gel. S4. Soak 10g of the composite wet gel in 150mL of anhydrous ethanol, and replace the anhydrous ethanol every 6 hours for a total of 5 times. The amount of anhydrous ethanol used each time is the same. Dry the composite wet gel after solvent exchange at 60℃ for 14 hours, then dry it at 120℃ for 5 hours. Then ball mill the dried product at 500r / min for 30 minutes to obtain ternary composite aerogel. S5. Mix 10g of the ternary composite aerogel, 250mL of xylene, 60g of epoxy-modified organosilicon resin and 0.5g of 2-ethyl-4-methylimidazole at 6000r / min for 0.75h, pour the mixture into a polytetrafluoroethylene mold and degas under vacuum at 70-90℃ for 1.5h. Then, place the mold at 105℃ for 3h and then at 155℃ for 5h. After natural cooling, demold to obtain aerogel-modified organosilicon resin.

[0055] The preparation method of the epoxy-modified organosilicon resin includes the following steps: 10g of hydroxyl-terminated polydimethylsiloxane, 4g of phenyltrimethoxysilane, 2.5g of diphenyldimethoxysilane, 0.125g of acetic acid, 15mL of dioxane, and 2.5mL of water were mixed and subjected to hydrolysis and condensation reaction at 90℃ for 5h. Then, 3.5g of γ-(2,3-epoxypropoxy)propyltrimethoxysilane was added, and condensation reaction was carried out at 90℃ for 7h to obtain epoxy-modified organosilicon resin.

[0056] Example 3

[0057] This embodiment provides a method for preparing aerogel-modified organosilicon resin, specifically including the following: The preparation method of the aerogel-modified organosilicon resin includes the following steps: S1. Mix 10g of melamine polyphosphate and 100mL of 1mol / L dilute hydrochloric acid at 60℃ and 500r / min for 2h, filter, wash, and then vacuum dry at 80℃ for 12h. Then disperse in 75mL of 75% ethanol aqueous solution to obtain a suspension. S2. The suspension, 3 mL of γ-(2,3-epoxypropoxy)propyltrimethoxysilane and 1.5 mL of 3-aminopropyltriethoxysilane were mixed and refluxed at 75 °C for 8 h. The reflux product was then vacuum dried at 80 °C for 24 h to obtain the surface-functionalized melamine polyphosphate. S3. Mix 10g of the surface-functionalized melamine polyphosphate with 200mL of 1wt% nanocellulose solution, add 40g of tetraethyl orthosilicate and 40mL of ethanol, adjust the pH to 2, stir and react at 40℃ for 4h, then adjust the pH to 7, and let stand at 40℃ for 24h to obtain composite wet gel. S4. Soak 10g of the composite wet gel in 125mL of anhydrous ethanol, and replace the anhydrous ethanol every 6 hours for a total of 5 times. The amount of anhydrous ethanol used each time is the same. Dry the composite wet gel after solvent exchange at 50℃ for 12 hours, then dry it at 110℃ for 4 hours. Then ball mill the dried product at 450r / min for 20 minutes to obtain ternary composite aerogel. S5. Mix 10g of the ternary composite aerogel, 225mL of xylene, 55g of epoxy-modified organosilicon resin and 0.4g of 2-ethyl-4-methylimidazole at 5000r / min for 0.5h, pour the mixture into a polytetrafluoroethylene mold and degas under vacuum at 80℃ for 1h. Then, place the mold at 100℃ for 2h and at 150℃ for 4h. After natural cooling, demold to obtain aerogel-modified organosilicon resin.

[0058] The preparation method of the epoxy-modified organosilicon resin includes the following steps: 10g of dihydroxyl-terminated polydimethylsiloxane, 3.5g of phenyltrimethoxysilane, 2g of diphenyldimethoxysilane, 0.1g of acetic acid, 10mL of dioxane, and 2mL of water were mixed and subjected to hydrolysis and polycondensation at 80℃ for 4h. Then, 2.5g of γ-(2,3-epoxypropoxy)propyltrimethoxysilane was added and polycondensation was carried out at 85℃ for 6h to obtain epoxy-modified organosilicon resin.

[0059] Example 4

[0060] This embodiment provides a method for preparing aerogel-modified organosilicon resin, specifically including the following: The preparation method of the aerogel-modified organosilicon resin includes the following steps: S1. Mix 50g of melamine polyphosphate and 500mL of 1mol / L dilute hydrochloric acid at 60℃ and 500r / min for 2h, filter, wash, and then vacuum dry at 80℃ for 12h. Then disperse in 400mL of 75% ethanol aqueous solution to obtain a suspension. S2. The suspension, 15 mL of γ-(2,3-epoxypropoxy)propyltrimethoxysilane and 7.5 mL of 3-aminopropyltriethoxysilane were mixed and refluxed at 75 °C for 8 h. The reflux product was then vacuum dried at 80 °C for 24 h to obtain the surface-functionalized melamine polyphosphate. S3. Mix 10g of the surface-functionalized melamine polyphosphate with 200mL of 1wt% nanocellulose solution, add 40g of tetraethyl orthosilicate and 40mL of ethanol, adjust the pH to 2, stir and react at 40℃ for 4h, then adjust the pH to 7, and let stand at 40℃ for 24h to obtain composite wet gel. S4. Soak 10g of the composite wet gel in 125mL of anhydrous ethanol, and replace the anhydrous ethanol every 6 hours for a total of 5 times. The amount of anhydrous ethanol used each time is the same. Dry the composite wet gel after solvent exchange at 50℃ for 12 hours, then dry it at 110℃ for 4 hours. Then ball mill the dried product at 450r / min for 20 minutes to obtain ternary composite aerogel. S5. Mix 1.5g of the ternary composite aerogel, 100mL of xylene, 28.5g of epoxy-modified organosilicon resin and 0.2g of 2-ethyl-4-methylimidazole at 5000r / min for 0.5h, pour the mixture into a polytetrafluoroethylene mold and degas under vacuum at 80℃ for 1h. Then, place the mold at 100℃ for 2h and then at 150℃ for 4h. After natural cooling, demold to obtain aerogel-modified organosilicon resin.

[0061] The preparation method of the epoxy-modified organosilicon resin includes the following steps: 55g of hydroxyl-terminated polydimethylsiloxane, 20g of phenyltrimethoxysilane, 10g of diphenyldimethoxysilane, 0.5g of acetic acid, 50mL of dioxane, and 10mL of water were mixed and subjected to hydrolysis and polycondensation at 80℃ for 4h. Then, 15g of γ-(2,3-epoxypropoxy)propyltrimethoxysilane was added and polycondensation was carried out at 85℃ for 6h to obtain epoxy-modified organosilicon resin.

[0062] Example 5

[0063] This embodiment provides a method for preparing aerogel-modified organosilicon resin, specifically including the following: The preparation method of the aerogel-modified organosilicon resin includes the following steps: S1. Mix 50g of melamine polyphosphate and 500mL of 1mol / L dilute hydrochloric acid at 60℃ and 500r / min for 2h, filter, wash, and then vacuum dry at 80℃ for 12h. Then disperse in 400mL of 75% ethanol aqueous solution to obtain a suspension. S2. The suspension, 15 mL of γ-(2,3-epoxypropoxy)propyltrimethoxysilane and 7.5 mL of 3-aminopropyltriethoxysilane were mixed and refluxed at 75 °C for 8 h. The reflux product was then vacuum dried at 80 °C for 24 h to obtain the surface-functionalized melamine polyphosphate. S3. Mix 10g of the surface-functionalized melamine polyphosphate with 200mL of 1wt% nanocellulose solution, add 40g of tetraethyl orthosilicate and 40mL of ethanol, adjust the pH to 2, stir and react at 40℃ for 4h, then adjust the pH to 7, and let stand at 40℃ for 24h to obtain composite wet gel. S4. Soak 10g of the composite wet gel in 125mL of anhydrous ethanol, and replace the anhydrous ethanol every 6 hours for a total of 5 times. The amount of anhydrous ethanol used each time is the same. Dry the composite wet gel after solvent exchange at 50℃ for 12 hours, then dry it at 110℃ for 4 hours. Then ball mill the dried product at 450r / min for 20 minutes to obtain ternary composite aerogel. S5. Mix 3g of the ternary composite aerogel, 100mL of xylene, 27g of epoxy-modified organosilicon resin and 0.2g of 2-ethyl-4-methylimidazole at 5000r / min for 0.5h, pour the mixture into a polytetrafluoroethylene mold and degas under vacuum at 80℃ for 1h. Then, place the mold at 100℃ for 2h and then at 150℃ for 4h. After natural cooling, demold to obtain aerogel-modified organosilicon resin.

[0064] The preparation method of the epoxy-modified organosilicon resin includes the following steps: 55g of hydroxyl-terminated polydimethylsiloxane, 20g of phenyltrimethoxysilane, 10g of diphenyldimethoxysilane, 0.5g of acetic acid, 50mL of dioxane, and 10mL of water were mixed and subjected to hydrolysis and polycondensation at 80℃ for 4h. Then, 15g of γ-(2,3-epoxypropoxy)propyltrimethoxysilane was added and polycondensation was carried out at 85℃ for 6h to obtain epoxy-modified organosilicon resin.

[0065] Example 6

[0066] This embodiment provides a method for preparing aerogel-modified organosilicon resin, specifically including the following: The preparation method of the aerogel-modified organosilicon resin includes the following steps: S1. Mix 50g of melamine polyphosphate and 500mL of 1mol / L dilute hydrochloric acid at 60℃ and 500r / min for 2h, filter, wash, and then vacuum dry at 80℃ for 12h. Then disperse in 400mL of 75% ethanol aqueous solution to obtain a suspension. S2. The suspension, 15 mL of γ-(2,3-epoxypropoxy)propyltrimethoxysilane and 7.5 mL of 3-aminopropyltriethoxysilane were mixed and refluxed at 75 °C for 8 h. The reflux product was then vacuum dried at 80 °C for 24 h to obtain the surface-functionalized melamine polyphosphate. S3. Mix 10g of the surface-functionalized melamine polyphosphate with 200mL of 1wt% nanocellulose solution, add 40g of tetraethyl orthosilicate and 40mL of ethanol, adjust the pH to 2, stir and react at 40℃ for 4h, then adjust the pH to 7, and let stand at 40℃ for 24h to obtain composite wet gel. S4. Soak 10g of the composite wet gel in 125mL of anhydrous ethanol, and replace the anhydrous ethanol every 6 hours for a total of 5 times. The amount of anhydrous ethanol used each time is the same. Dry the composite wet gel after solvent exchange at 50℃ for 12 hours, then dry it at 110℃ for 4 hours. Then ball mill the dried product at 450r / min for 20 minutes to obtain ternary composite aerogel. S5. Mix 4.5g of the ternary composite aerogel, 100mL of xylene, 25.5g of epoxy-modified organosilicon resin and 0.2g of 2-ethyl-4-methylimidazole at 5000r / min for 0.5h, pour the mixture into a polytetrafluoroethylene mold and degas under vacuum at 80℃ for 1h. Then, place the mold at 100℃ for 2h and then at 150℃ for 4h. After natural cooling, demold to obtain aerogel-modified organosilicon resin.

[0067] The preparation method of the epoxy-modified organosilicon resin includes the following steps: 55g of hydroxyl-terminated polydimethylsiloxane, 20g of phenyltrimethoxysilane, 10g of diphenyldimethoxysilane, 0.5g of acetic acid, 50mL of dioxane, and 10mL of water were mixed and subjected to hydrolysis and polycondensation at 80℃ for 4h. Then, 15g of γ-(2,3-epoxypropoxy)propyltrimethoxysilane was added and polycondensation was carried out at 85℃ for 6h to obtain epoxy-modified organosilicon resin.

[0068] Example 7

[0069] This embodiment provides a method for preparing aerogel-modified organosilicon resin, specifically including the following: The preparation method of the aerogel-modified organosilicon resin includes the following steps: S1. Mix 50g of melamine polyphosphate and 500mL of 1mol / L dilute hydrochloric acid at 60℃ and 500r / min for 2h, filter, wash, and then vacuum dry at 80℃ for 12h. Then disperse in 400mL of 75% ethanol aqueous solution to obtain a suspension. S2. The suspension, 15 mL of γ-(2,3-epoxypropoxy)propyltrimethoxysilane and 7.5 mL of 3-aminopropyltriethoxysilane were mixed and refluxed at 75 °C for 8 h. The reflux product was then vacuum dried at 80 °C for 24 h to obtain the surface-functionalized melamine polyphosphate. S3. Mix 10g of the surface-functionalized melamine polyphosphate with 200mL of 1wt% nanocellulose solution, add 40g of tetraethyl orthosilicate and 40mL of ethanol, adjust the pH to 2, stir and react at 40℃ for 4h, then adjust the pH to 7, and let stand at 40℃ for 24h to obtain composite wet gel. S4. Soak 10g of the composite wet gel in 125mL of anhydrous ethanol, and replace the anhydrous ethanol every 6 hours for a total of 5 times. The amount of anhydrous ethanol used each time is the same. Dry the composite wet gel after solvent exchange at 50℃ for 12 hours, then dry it at 110℃ for 4 hours. Then ball mill the dried product at 450r / min for 20 minutes to obtain ternary composite aerogel. S5. Mix 6g of the ternary composite aerogel, 100mL of xylene, 24g of epoxy-modified organosilicon resin and 0.2g of 2-ethyl-4-methylimidazole at 5000r / min for 0.5h, pour the mixture into a polytetrafluoroethylene mold and degas under vacuum at 80℃ for 1h. Then, place the mold at 100℃ for 2h and at 150℃ for 4h. After natural cooling, demold to obtain aerogel-modified organosilicon resin.

[0070] The preparation method of the epoxy-modified organosilicon resin includes the following steps: 55g of hydroxyl-terminated polydimethylsiloxane, 20g of phenyltrimethoxysilane, 10g of diphenyldimethoxysilane, 0.5g of acetic acid, 50mL of dioxane, and 10mL of water were mixed and subjected to hydrolysis and polycondensation at 80℃ for 4h. Then, 15g of γ-(2,3-epoxypropoxy)propyltrimethoxysilane was added and polycondensation was carried out at 85℃ for 6h to obtain epoxy-modified organosilicon resin.

[0071] Example 8

[0072] This embodiment provides a method for preparing aerogel-modified organosilicon resin, specifically including the following: The preparation method of the aerogel-modified organosilicon resin includes the following steps: S1. Mix 50g of melamine polyphosphate and 500mL of 1mol / L dilute hydrochloric acid at 60℃ and 500r / min for 2h, filter, wash, and then vacuum dry at 80℃ for 12h. Then disperse in 400mL of 75% ethanol aqueous solution to obtain a suspension. S2. The suspension, 15 mL of γ-(2,3-epoxypropoxy)propyltrimethoxysilane and 7.5 mL of 3-aminopropyltriethoxysilane were mixed and refluxed at 75 °C for 8 h. The reflux product was then vacuum dried at 80 °C for 24 h to obtain the surface-functionalized melamine polyphosphate. S3. Mix 10g of the surface-functionalized melamine polyphosphate with 200mL of 1wt% nanocellulose solution, add 20g of tetraethyl orthosilicate and 40mL of ethanol, adjust the pH to 2, stir and react at 40℃ for 4h, then adjust the pH to 7, and let stand at 40℃ for 24h to obtain composite wet gel. S4. Soak 10g of the composite wet gel in 125mL of anhydrous ethanol, and replace the anhydrous ethanol every 6 hours for a total of 5 times. The amount of anhydrous ethanol used each time is the same. Dry the composite wet gel after solvent exchange at 50℃ for 12 hours, then dry it at 110℃ for 4 hours. Then ball mill the dried product at 450r / min for 20 minutes to obtain ternary composite aerogel. S5. Mix 4.5g of the ternary composite aerogel, 100mL of xylene, 25.5g of epoxy-modified organosilicon resin and 0.2g of 2-ethyl-4-methylimidazole at 5000r / min for 0.5h, pour the mixture into a polytetrafluoroethylene mold and degas under vacuum at 80℃ for 1h. Then, place the mold at 100℃ for 2h and then at 150℃ for 4h. After natural cooling, demold to obtain aerogel-modified organosilicon resin.

[0073] The preparation method of the epoxy-modified organosilicon resin includes the following steps: 55g of hydroxyl-terminated polydimethylsiloxane, 20g of phenyltrimethoxysilane, 10g of diphenyldimethoxysilane, 0.5g of acetic acid, 50mL of dioxane, and 10mL of water were mixed and subjected to hydrolysis and polycondensation at 80℃ for 4h. Then, 15g of γ-(2,3-epoxypropoxy)propyltrimethoxysilane was added and polycondensation was carried out at 85℃ for 6h to obtain epoxy-modified organosilicon resin.

[0074] Example 9

[0075] This embodiment provides a method for preparing aerogel-modified organosilicon resin, specifically including the following: The preparation method of the aerogel-modified organosilicon resin includes the following steps: S1. Mix 50g of melamine polyphosphate and 500mL of 1mol / L dilute hydrochloric acid at 60℃ and 500r / min for 2h, filter, wash, and then vacuum dry at 80℃ for 12h. Then disperse in 400mL of 75% ethanol aqueous solution to obtain a suspension. S2. The suspension, 15 mL of γ-(2,3-epoxypropoxy)propyltrimethoxysilane and 7.5 mL of 3-aminopropyltriethoxysilane were mixed and refluxed at 75 °C for 8 h. The reflux product was then vacuum dried at 80 °C for 24 h to obtain the surface-functionalized melamine polyphosphate. S3. Mix 10g of the surface-functionalized melamine polyphosphate with 200mL of 1wt% nanocellulose solution, add 60g of tetraethyl orthosilicate and 40mL of ethanol, adjust the pH to 2, stir and react at 40℃ for 4h, then adjust the pH to 7, and let stand at 40℃ for 24h to obtain composite wet gel. S4. Soak 10g of the composite wet gel in 125mL of anhydrous ethanol, and replace the anhydrous ethanol every 6 hours for a total of 5 times. The amount of anhydrous ethanol used each time is the same. Dry the composite wet gel after solvent exchange at 50℃ for 12 hours, then dry it at 110℃ for 4 hours. Then ball mill the dried product at 450r / min for 20 minutes to obtain ternary composite aerogel. S5. Mix 4.5g of the ternary composite aerogel, 100mL of xylene, 25.5g of epoxy-modified organosilicon resin and 0.2g of 2-ethyl-4-methylimidazole at 5000r / min for 0.5h, pour the mixture into a polytetrafluoroethylene mold and degas under vacuum at 80℃ for 1h. Then, place the mold at 100℃ for 2h and then at 150℃ for 4h. After natural cooling, demold to obtain aerogel-modified organosilicon resin.

[0076] The preparation method of the epoxy-modified organosilicon resin includes the following steps: 55g of hydroxyl-terminated polydimethylsiloxane, 20g of phenyltrimethoxysilane, 10g of diphenyldimethoxysilane, 0.5g of acetic acid, 50mL of dioxane, and 10mL of water were mixed and subjected to hydrolysis and polycondensation at 80℃ for 4h. Then, 15g of γ-(2,3-epoxypropoxy)propyltrimethoxysilane was added and polycondensation was carried out at 85℃ for 6h to obtain epoxy-modified organosilicon resin.

[0077] Comparative Example 1

[0078] This comparative example provides a method for preparing an aerogel-modified organosilicon resin, specifically including the following: The preparation method of the aerogel-modified organosilicon resin includes the following steps: 2.25g of commercial silica aerogel powder and 2.25g of commercially available melamine polyphosphate were added to 100mL of xylene in a 250mL single-necked flask and sonicated at room temperature for 30min to obtain a suspension. Then, 25.5g of epoxy-modified organosilicon resin and 0.2g of 2-ethyl-4-methylimidazole were added and mixed at 5000r / min for 0.5h. The mixture was then poured into a polytetrafluoroethylene mold and vacuum degassed at 80℃ for 1h. The mold was then kept at 100℃ for 2h and then at 150℃ for 4h. After natural cooling, the mixture was demolded to obtain aerogel-modified organosilicon resin. The commercial silica aerogel powder was purchased from Langmiao Environmental Technology (Tianjin) Co., Ltd. The commercially available melamine polyphosphate was purchased from Jiangsu Suli Fine Chemical Co., Ltd., and its trade name is Fulimei-109. The preparation method of the epoxy-modified organosilicon resin includes the following steps: 55g of hydroxyl-terminated polydimethylsiloxane, 20g of phenyltrimethoxysilane, 10g of diphenyldimethoxysilane, 0.5g of acetic acid, 50mL of dioxane, and 10mL of water were mixed and subjected to hydrolysis and polycondensation at 80℃ for 4h. Then, 15g of γ-(2,3-epoxypropoxy)propyltrimethoxysilane was added and polycondensation was carried out at 85℃ for 6h to obtain epoxy-modified organosilicon resin.

[0079] Comparative Example 2

[0080] This comparative example provides a method for preparing an aerogel-modified organosilicon resin, specifically including the following: The preparation method of the aerogel-modified organosilicon resin includes the following steps: S1. Mix 50g of melamine polyphosphate and 500mL of 1mol / L dilute hydrochloric acid at 60℃ and 500r / min for 2h, filter, wash, and then vacuum dry at 80℃ for 12h. Then disperse in 400mL of 75% ethanol aqueous solution to obtain a suspension. S2. The suspension, 15 mL of γ-(2,3-epoxypropoxy)propyltrimethoxysilane and 7.5 mL of 3-aminopropyltriethoxysilane were mixed and refluxed at 75 °C for 8 h. The reflux product was then vacuum dried at 80 °C for 24 h to obtain the surface-functionalized melamine polyphosphate. S3. Mix 10g of the surface-functionalized melamine polyphosphate with 200mL of 1wt% nanocellulose solution, add 60g of tetraethyl orthosilicate and 40mL of ethanol, adjust the pH to 2, stir and react at 40℃ for 4h, then adjust the pH to 7, and let stand at 40℃ for 24h to obtain composite wet gel. S4. Soak 10g of the composite wet gel in 125mL of anhydrous ethanol, and replace the anhydrous ethanol every 6 hours for a total of 5 times. The amount of anhydrous ethanol used each time is the same. Dry the composite wet gel after solvent exchange at 50℃ for 12 hours, then dry it at 110℃ for 4 hours. Then ball mill the dried product at 450r / min for 20 minutes to obtain ternary composite aerogel. S5. Mix 4.5g of the ternary composite aerogel, 100mL of xylene, 25.5g of commercially available organosilicon resin and 0.2g of 2-ethyl-4-methylimidazole at 5000r / min for 0.5h, pour the mixture into a polytetrafluoroethylene mold and vacuum degas at 80℃ for 1h. Then, place the mold at 100℃ for 2h and at 150℃ for 4h. After natural cooling, demold to obtain aerogel-modified organosilicon resin. The commercially available silicone resin was purchased from Jinan Dahui Chemical Technology Co., Ltd.

[0081] For the aerogel-modified silicone resins in Examples 4-9 and Comparative Examples 1-2, the apparent density of the composite materials was determined according to GB / T 6343; the tensile strength was determined according to GB / T 1040.2-2022, with a tensile rate set at 2 mm / min; the flexural strength was determined according to GB / T 9341, using a three-point loading mode and a flexural rate of 2 mm / min; the fracture toughness was determined according to ASTM D5045, using a single-sided notched specimen to measure the critical stress intensity factor and critical strain energy release rate of the plastic; the thermal conductivity was determined according to GB / T 10295-2008; the limiting oxygen index was determined according to GB / T 2406.2-2009; the flame retardancy rating was determined according to UL 94 standard, with a specimen thickness of 1.6 mm; and the results were determined according to GB / T 33047.1-2016 "Plastics Polymers - Thermogravimetric Analysis (TG)". Part 1: General Rules The initial decomposition temperature and char residue were determined at a heating rate of 10℃ / min under a nitrogen atmosphere. The test results are shown in Table 1.

[0082]

[0083] The above are all preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, all equivalent changes made in accordance with the structure, shape and principle of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing an aerogel-modified organosilicon resin, characterized in that, Includes the following steps: S1. Melamine polyphosphate and dilute hydrochloric acid are mixed and then filtered, washed and dried in sequence, and then dispersed in an ethanol aqueous solution to obtain a suspension. S2. The suspension, γ-(2,3-epoxypropoxy)propyltrimethoxysilane and 3-aminopropyltriethoxysilane are mixed and refluxed at 70-80°C to obtain surface-functionalized melamine polyphosphate. S3. After mixing the surface-functionalized melamine polyphosphate with the nanocellulose solution, tetraethyl orthosilicate and ethanol are added, the pH is adjusted to 1.5-2.5, and the mixture is stirred at 35-45℃. Then the pH is adjusted to 6.5-7.5, and the mixture is allowed to stand and age at 35-45℃ to obtain a composite wet gel. S4. The composite wet gel is immersed in anhydrous ethanol, and solvent exchange and drying are performed sequentially to obtain ternary composite aerogel. S5. The ternary composite aerogel, xylene, epoxy-modified organosilicon resin and 2-ethyl-4-methylimidazole are mixed and poured into a polytetrafluoroethylene mold for vacuum degassing, programmed temperature rise curing, and demolding after natural cooling to obtain aerogel blend modified organosilicon resin.

2. The method for preparing aerogel-modified organosilicon resin according to claim 1, characterized in that, In S1, the mass-to-volume ratio of melamine polyphosphate to dilute hydrochloric acid is 1 g:(8-12) mL, and the concentration of the dilute hydrochloric acid is 0.75-1.25 mol / L; and / or In S1, the mixing is carried out under stirring conditions, with a stirring rate of 300-800 r / min, a temperature of 50-70℃, and a time of 1.5-2.5 h; and / or In S1, the drying is vacuum drying at a temperature of 75-85℃ for 10-14 hours; and / or In S1, the mass-to-volume ratio of the melamine polyphosphate to the ethanol aqueous solution is 1 g: (5-10) mL, and the volume concentration of the ethanol aqueous solution is 70%-80%.

3. The method for preparing aerogel-modified organosilicon resin according to claim 1, characterized in that, In S2, the mass-to-volume ratio of melamine polyphosphate, γ-(2,3-epoxypropoxy)propyltrimethoxysilane, and 3-aminopropyltriethoxysilane in the suspension is 1 g : (0.2-0.4) mL : (0.1-0.2) mL; and / or In S2, the reflux reaction time is 6-10 hours; and / or In step S2, after the reflux reaction is completed, the reflux product is vacuum dried to obtain the surface-functionalized melamine polyphosphate. The vacuum drying temperature is 70-90°C and the time is 20-28 hours.

4. The method for preparing aerogel-modified organosilicon resin according to claim 1, characterized in that, In S3, the mass-to-volume ratio of the surface-functionalized melamine polyphosphate to the nanocellulose solution is 1 g:(15-25) mL, and the mass concentration of the nanocellulose solution is 0.5-1.5 wt%; and / or In S3, the mass-to-volume ratio of the surface-functionalized melamine polyphosphate, tetraethyl orthosilicate, and ethanol is 1 g:(3-5) g:(3-5) mL; and / or In S3, the stirring reaction time is 3-5 hours; and / or In S3, the settling and aging time is 20-28 hours.

5. The method for preparing aerogel-modified organosilicon resin according to claim 1, characterized in that, In S4, the mass-to-volume ratio of the composite wet gel to anhydrous ethanol is 1 g: (10-15) mL; and / or In S4, the solvent exchange specifically includes the following steps: The composite wet gel was soaked in anhydrous ethanol, and the anhydrous ethanol was replaced every 6 hours for a total of 5 times, with the same amount of anhydrous ethanol used each time; and / or In step S4, the drying process specifically includes the following steps: The solvent-exchanged composite wet gel was dried at 40-60℃ for 10-14 hours, and then dried at 100-120℃ for 3-5 hours to obtain a ternary composite aerogel.

6. The method for preparing aerogel-modified organosilicon resin according to claim 1, characterized in that, In step S4, after drying, the dried product is further ball-milled at a speed of 400-500 r / min for 10-30 min to obtain the ternary composite aerogel.

7. The method for preparing aerogel-modified organosilicon resin according to claim 1, characterized in that, In S5, the mass-to-volume ratio of the ternary composite aerogel, xylene, epoxy-modified organosilicon resin, and 2-ethyl-4-methylimidazole is 1 g : (20-25) mL : (5-6) g : (0.03-0.05) g; and / or In S5, the mixing is carried out under stirring conditions, with a rotation speed of 4000-6000 r / min and a time of 0.25-0.75 h; and / or In S5, the vacuum degassing temperature is 70-90℃, and the time is 0.5-1.5h; and / or In S5, the programmed temperature curing includes the following steps: first, placing the mold at 95-105℃ for 1-3 hours, then placing it at 145-155℃ for 3-5 hours; and / or In S5, the preparation method of the epoxy-modified organosilicon resin includes the following steps: A mixture of dihydroxyl-terminated polydimethylsiloxane, phenyltrimethoxysilane, diphenyldimethoxysilane, acetic acid, dioxane, and water was subjected to hydrolysis and condensation reactions at 70-90℃. Then, γ-(2,3-epoxypropoxy)propyltrimethoxysilane was added, and a condensation reaction was carried out at 80-90℃ to obtain an epoxy-modified organosilicon resin.

8. The method for preparing aerogel-modified organosilicon resin according to claim 7, characterized in that, The mass-to-volume ratio of the dihydroxyl-terminated polydimethylsiloxane, phenyltrimethoxysilane, diphenyldimethoxysilane, acetic acid, dioxane, and water is 1 g : (0.3-0.4) g : (0.15-0.25) g : (0.0075-0.0125) g : (0.5-1.5) mL : (0.15-0.25) mL; and / or The mass ratio of the dihydroxyl-terminated polydimethylsiloxane to γ-(2,3-epoxypropoxy)propyltrimethoxysilane is 1 g : (0.15-0.35) g; and / or The hydrolysis and polycondensation reactions take 3-5 hours; and / or The polycondensation reaction takes 5-7 hours.

9. An aerogel-modified organosilicon resin, characterized in that, It is prepared by the method for preparing aerogel blend modified organosilicon resin according to any one of claims 1-8.

10. The application of the aerogel-modified organosilicon resin according to claim 9 in thermal insulation materials.

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