A method for preparing heteroatom-modified silicone resin and its high-temperature resistant adhesive

Abstract

To address the problems of poor mechanical properties, weak adhesion to substrates, and low residual strength in silicone-based polymers, this invention proposes a method for preparing heteroatom-modified silicone resin and its high-temperature resistant adhesive. The method includes: dissolving trifunctional and difunctional siloxane monomers in organic solvent A, mixing them, adding an acidic aqueous solution dropwise, heating the mixture, and then removing the solvent to obtain a low-viscosity silicone resin precursor; dissolving acylferrocene in organic solvent B, adding a heteroatom solution dropwise, continuing the reaction after the addition is complete, and then cooling and crystallizing to obtain a ligand compound of acylferrocene and heteroatoms; dissolving the low-viscosity silicone resin precursor and the acylferrocene-heteroatoms ligand compound in alcohol solvent A, reacting the mixture, and then removing the solvent to obtain the heteroatom-modified silicone resin. The heteroatom-modified silicone resin prepared by this invention exhibits excellent high-temperature resistance, and the prepared high-temperature resistant adhesive possesses good high-temperature bonding and sealing performance and high-temperature mechanical strength over a wide temperature range.

Description

Technical Field

[0001] This invention belongs to the field of high-temperature resistant materials, specifically relating to a method for preparing a heteroatom-modified silicone resin and its high-temperature resistant adhesive. Background Technology

[0002] High-temperature resistant silicone resin-based adhesives possess advantages such as high strength and uniform stress distribution, and have replaced traditional riveting and welding methods in various fields, including the fabrication of high-temperature resistant components in aerospace, the installation of thermal protection sealing systems, and the repair of thermal insulation sealing systems. However, due to the flexibility of their molecular chains and chemical inertness, silicone polymers suffer from poor mechanical properties, weak adhesion to substrates, and low residual strength. Therefore, there is an urgent need to reinforce and toughen the ceramic components of high-temperature resistant silicone-based adhesives and sealants. However, traditional methods of adding whiskers, carbon nanotubes, and nanowires exhibit significant agglomeration, making it difficult to uniformly disperse them in the adhesive and sealant, resulting in limited reinforcing effects and failing to meet the new demands of the aerospace industry for high-temperature resistant adhesives and sealants. Therefore, developing novel high-temperature resistant adhesive and sealant materials with higher heat resistance and higher residual quality and strength at high temperatures is of great significance. Summary of the Invention

[0003] To address the technical problems existing in the prior art, the present invention provides a method for preparing heteroatom-modified silicone resin and its high-temperature resistant adhesive.

[0004] This invention first discloses a heteroatom-modified silicone resin, whose general formula is:

[0005]

[0006] Wherein, R1 is a hydroxyl group, and R2 is a methyl or vinyl group.

[0007] R3 represents structure I or II.

[0008]

[0009]

[0010] n is an integer between 200 and 8000, and M is one of the transition metal atoms such as Ti, Zr, and Hf.

[0011] This invention further proposes a method for preparing the above-mentioned heteroatom-modified silicone resin, specifically as follows:

[0012] 1. Dissolve trifunctional siloxane monomers and difunctional siloxane monomers in organic solvent A, mix them evenly, and then add acidic aqueous solution dropwise at 45-55℃ for 0.5-1h. Raise the temperature to 60-70℃ and react for 2-4h. Remove the solvent to obtain a low-viscosity silicone resin precursor.

[0013] 2. Dissolve acylferrocene in organic solvent B, add heteroatom solution dropwise at 45-55℃ for 0.25-0.5h, continue the reaction for 4-6h after the addition is complete, cool down and crystallize to obtain acylferrocene ligand compound with heteroatom;

[0014] 3. Dissolve the low-viscosity silicone resin precursor, acyl ferrocene and heteroatom ligand compound in alcohol solvent A, react at 70-90℃ for 4-6 hours, remove the solvent, and obtain heteroatom modified silicone resin.

[0015] The trifunctional siloxane monomer mentioned in step one is at least one of methyltrimethoxysilane, phenyltrimethoxysilane, vinyltriethoxysilane, etc.; the difunctional siloxane monomer is at least one of diphenyldimethoxysilane, dimethyldimethoxysilane, methylphenyldimethoxysilane; the mass ratio of the trifunctional siloxane monomer, the difunctional siloxane monomer, organic solvent A, and acidic aqueous solution is 1-3:1-2:1-2:2-3.

[0016] The acyl ferrocene mentioned in step two is at least one of formyl ferrocene, acetyl ferrocene, butyryl ferrocene, 1,1'-diformyl ferrocene, 1,1'-diacetyl ferrocene, and 1,1'-dibutyryl ferrocene; the heteroatom solution is boric acid, tetrabutyl titanate, zirconium propoxide, or hafnium propoxide, and the mass ratio of acyl ferrocene to heteroatom solution is 2-6:1.

[0017] The acylferrocene and heteroatom ligand compound mentioned in step three is 20-40 wt% of the low-viscosity silicone resin precursor.

[0018] The acidic aqueous solution mentioned in step one is at least one of hydrochloric acid, acetic acid, oxalic acid, and carbonic acid, and the concentration of the acidic aqueous solution is 0.1-0.4 wt%.

[0019] The organic solvent A is at least one of tetrahydrofuran, ethanol, isopropanol, and acetone; the organic solvent B is at least one of isopropanol, DMF, ethyl acetate, and ethanol.

[0020] This invention also proposes the application of the above-mentioned heteroatom-modified silicone resin in high-temperature adhesives, comprising the following steps:

[0021] (1) The reinforcing agent, dispersant, sintering aid and carbon source are ball-milled to obtain a mixed filler with uniform particle size;

[0022] (2) The mixed filler and the heteroatom-modified silicone resin matrix are subjected to strong mechanical mixing;

[0023] (3) After mixing evenly, add organic solvent C and coupling agent, and stir to obtain hybrid silicone resin-based high-temperature resistant adhesive;

[0024] The carbon source is carbon nanotubes, graphite powder, carbon fiber, graphene, or biomass carbon source.

[0025] The method for preparing the biomass carbon source is as follows: placing the biomass material in a hydrothermal reactor and reacting it at 180-350℃ for 24-48 hours to obtain the biomass carbon source. The biomass material is at least one of rice husk, coconut shell, durian peel, and straw.

[0026] The sintering aid is at least one of zinc borate, AlN, and B4C; the organic solvent C is at least one of ethanol, isopropanol, and acetone; the reinforcing agent is at least one of glass fiber, carbon fiber, carbon black, SiC, ZrB2, TiB2, and HfB2; the dispersant is at least one of hollow glass microspheres, fumed silica, and hollow phenolic microspheres; and the coupling agent is at least one of γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, and γ-(methacryloyloxy)propyltrimethoxysilane.

[0027] The principle of this invention is as follows:

[0028] Currently, the heat resistance and high-temperature residue strength of pure silicone resin used in high-temperature adhesives need further improvement. Therefore, this design incorporates heteroatoms into the silicone resin to increase the bond energy of Si-O-Si bonds, thereby improving the heat resistance of the silicone resin and altering the ceramic phase composition. Simultaneously, in-situ growth of SiC nanowires at high temperatures enhances residue strength.

[0029] First, the alkoxy group (Si-OCH3) of the silane monomer undergoes acid-catalyzed hydrolysis to generate Si-OH, which then undergoes dehydration condensation at a lower temperature to form a Si-O-Si bond and generate a phenyl-containing silanol precursor. Second, zirconium ions (Zr) in a zirconium propoxide solution are utilized... +4 The coordination of zirconium ions with the carbonyl group (C=O) in acetylferrocene forms an intermetallic compound ligand. Because the outermost d-level of the zirconium ion has empty orbitals and the carbonyl group of the ligand is a strong-field ligand, it will adopt dsp² hybridization, easily forming a planar quadrilateral ligand structure. Then, the intermetallic compound ligand is introduced into the silicone resin structure through the π-π stacking interaction between the benzene ring of the silanol precursor and the cyclopentadiene ring in the acetylferrocene. Since the alkoxy-linked benzene ring in the silanol precursor is in a strongly electron-rich state, while the cyclopentadiene ring in the acetylferrocene is in a strongly electron-deficient state, their π-π stacking interaction is stronger, allowing for the regulation of the phenyl content. This method of introducing heteroatoms into silicone resin is novel. Firstly, it solves the problem of high hydrolysis rates of heteroatom monomers and silane monomers; secondly, it releases transition metal ions at high temperatures, promoting ceramic transformation; and thirdly, it has universal applicability to most coordinateable metal ions.

[0030] The improved adhesive performance of high-temperature adhesives lies in the Fe during the pyrolysis of the heteroatom-modified silicone resin matrix. 2+ Ions are reduced to elemental Fe, which liquefies at high temperature to form metal catalytic centers. These centers adsorb SiO and CO gases generated by the pyrolysis of the resin matrix and biomass carbon source. The SiO and CO gases are then dissolved, diffused, and precipitated within the metal catalytic centers, promoting the growth of SiC nanowires. Simultaneously, the special element (N) from the biomass carbon source adheres to the surface of the metal catalyst, providing more active sites and enhancing catalytic activity. The in-situ self-grown SiC nanowires avoid stress concentration-induced damage caused by agglomeration. Furthermore, the in-situ self-grown SiC nanowires have a certain repair effect on cracks generated by pyrolysis. Additionally, the fracture, pull-out, and crack deflection of SiC nanowires under external loads dissipate more energy, and the cracks terminate in areas with abundant SiC nanowire growth. Therefore, the combined effect of the added functional ceramic components and SiC nanowires improves their high-temperature bonding strength. Furthermore, under the influence of specially designed intermetallic compound ligands in the hybrid silicon resin matrix, the Fe elemental metal catalytic center attaches to the surface of transition metal carbides and oxides, forming a heterostructure catalyst. Since the lattice constant of transition metal carbides and oxides is greater than that of Fe, Fe is stretched, its lattice constant increases, and the d-band center shifts upward. The bonding stability between the surface of the Fe elemental metal catalytic center and the gaseous element is improved, thus enhancing the adsorption capacity of SiO and CO gases. Through the synergistic promoting effect of transition metal atoms and Fe elemental elements, the growth efficiency of SiC nanowires is improved, thereby further enhancing the bonding strength of the high-temperature resistant adhesive.

[0031] Beneficial effects:

[0032] The heteroatom-modified silicone resin prepared by this invention exhibits excellent high-temperature resistance. Furthermore, when applied to high-temperature adhesives, the heteroatoms catalyze the growth of SiC nanowires, improving their growth efficiency and repairing microcracks caused by pyrolysis. At around 1000℃, the silicates and borates formed by the reaction of the pyrolysis products of the heteroatom-modified silicone resin with functional fillers enhance adhesion. At 1600℃ and higher temperatures, utilizing the carbon source and special elements provided by biomass carbon materials, the in-situ self-growth of a greater number and higher aspect ratio SiC nanowires is promoted through multi-atom synergy, strengthening and toughening the ceramic phase. This forms an integrated ceramic structure of SiC, heteroatom carbides, and borides, maintaining excellent high-temperature adhesive properties. The prepared high-temperature adhesive possesses good high-temperature bonding and sealing performance over a wide temperature range, exhibits high mechanical strength at high temperatures, and also boasts the advantages of being environmentally friendly. Attached Figure Description

[0033] Figure 1The infrared spectrum of the methylphenyl silicone resin precursor in Example 1 is shown below.

[0034] Figure 2 The infrared spectrum of zirconium hybrid silicon resin in Example 1;

[0035] Figure 3 XRD comparison analysis of methylphenyl silicone resin precursor and zirconium hybrid silicone resin at high temperature in Example 1;

[0036] Figure 4 XPS structure analysis of zirconium hybrid silicon resin in Example 1;

[0037] Figure 5 The TGA curves of the methylphenyl silicone resin precursor and zirconium hybrid silicone resin under nitrogen atmosphere in Example 1 are shown.

[0038] Figure 6 The growth morphology of zirconium hybrid silicon resin SiC nanowires at 11600℃ is shown in Example 1.

[0039] Figure 7 The TG curves of the zirconium hybrid silicone resin-based high-temperature resistant adhesive in air and nitrogen atmospheres are shown in Example 6.

[0040] Figure 8 Example 6: Bond strength of zirconium hybrid silicone resin-based high-temperature resistant adhesive at 1600 degrees Celsius under different ablation times;

[0041] Figure 9 SEM image of SiC nanowires grown on the surface of biomass carbon source in Example 6;

[0042] Figure 10 SEM image of the solid-gas-liquid growth mechanism of SiC nanowires in Example 6;

[0043] Figure 11 Here is a SEM image of the crack deflection caused by SiC nanowires in Example 6;

[0044] Figure 12 This is a SEM image of the SiC nanowire composite with the matrix in Example 6;

[0045] Figure 13 Here is a SEM image of the surface repair effect of mass growth of SiC nanowires in Example 6;

[0046] Figure 14 This is a SEM image of the crack termination point at the location of a large number of SiC nanowires in Example 6.

[0047] Figure 15 Example 7: Bond strength of titanium hybrid silicone resin-based high-temperature resistant adhesive at 1600 degrees Celsius under different ablation times;

[0048] Figure 16Example 7 shows the growth morphology of SiC nanowires at 1600 degrees Celsius using a titanium-hybrid silicon resin-based high-temperature resistant adhesive. Detailed Implementation

[0049] This invention proposes a method for preparing heteroatom-modified silicone resin, specifically as follows:

[0050] I. Dissolve trifunctional and difunctional siloxane monomers in organic solvent A, mix thoroughly, and then add acidic aqueous solution dropwise at 45-55℃ for 0.5-1 h. Increase the temperature to 60-70℃ and react for 2-4 h. Remove the solvent to obtain a low-viscosity silicone resin precursor. The trifunctional siloxane monomer is at least one of methyltrimethoxysilane, phenyltrimethoxysilane, vinyltriethoxysilane, etc.; the difunctional siloxane monomer is at least one of diphenyldimethoxysilane, dimethyldimethoxysilane, methylphenyldimethoxysilane; the mass ratio of trifunctional siloxane monomer, difunctional siloxane monomer, organic solvent A, and acidic aqueous solution is 1-3:1-2:1-2:2-3. The organic solvent A is at least one of tetrahydrofuran, ethanol, isopropanol, and acetone; the acidic aqueous solution is at least one of hydrochloric acid, acetic acid, oxalic acid, and carbonic acid, and the concentration of the acidic aqueous solution is 0.1-0.4 wt%.

[0051] 2. Dissolve acylferrocene in organic solvent B, and add a heteroatom solution dropwise at 45-55℃ for 0.25-0.5 h. After the addition is complete, continue the reaction for 4-6 h, cool, crystallize, and purify to obtain the acylferrocene-heteroatom ligand compound. The acylferrocene is at least one of formylferrocene, acetylferrocene, butyrylferrocene, 1,1'-diformylferrocene, 1,1'-diacetylferrocene, and 1,1'-dibutyrylferrocene. The heteroatom solution is boric acid, tetrabutyl titanate, zirconium n-propoxide, or hafnium n-propoxide, and the mass ratio of acylferrocene to heteroatom solution is 2-6:1. Organic solvent B is at least one of isopropanol, DMF, ethyl acetate, and ethanol.

[0052] 3. Dissolve the low-viscosity silicone resin precursor, acylferrocene, and heteroatom ligand compound in alcohol solvent A, react at 70-90℃ for 4-6 hours, remove the solvent, and obtain heteroatom-modified silicone resin. The acylferrocene and heteroatom ligand compound constitute 20-40 wt% of the low-viscosity silicone resin precursor.

[0053] Examples 1-5 are specific embodiments of heteroatom-modified silicone resin and its preparation method. The acyl ferrocene used in step two can be either self-made or purchased; Example 1 uses self-made acyl ferrocene, while Example 2 uses commercially available acyl ferrocene.

[0054] The method for preparing acetyl ferrocene is as follows: 10 parts of ferrocene are dissolved in 15 parts of dichloromethane, 10 parts of acetyl chloride-aluminum trichloride solution are added dropwise at 0℃, the temperature is raised to 10℃ and reacted for 1 hour, and then the mixture is purified after reacting at room temperature for 6 hours to obtain acetyl ferrocene.

[0055] Example 1:

[0056] 1. Dissolve 12 parts of methyltrimethoxysilane, 13 parts of phenyltrimethoxysilane and 14 parts of dimethyldimethoxysilane in 13 parts of ethanol, mix well, and then add 22 parts of hydrochloric acid aqueous solution (concentration of 0.1 wt%) dropwise at 50°C for 0.5 h. After heating to 65°C and reacting for 2 h, remove the solvent to obtain a low-viscosity silicone resin precursor.

[0057] 2. Dissolve 10 parts of self-made acetylferrocene in isopropanol, add 4 parts of n-propoxide zirconium solution dropwise at 50°C for 0.25 h, and continue the reaction for 6 h after the addition is complete. Cool down and crystallize to obtain acetylferrocene ligand compound with zirconium atoms.

[0058] 3. Dissolve 100 parts of low-viscosity silicone resin precursor, 20 parts of acetylferrocene and heteroatom ligand compound in ethanol, react at 80°C for 4 hours, remove the solvent, and obtain zirconium atom modified silicone resin.

[0059] Example 2:

[0060] 1. Dissolve 11 parts of vinyltriethoxysilane, 12 parts of phenyltrimethoxysilane and 13 parts of dimethyldimethoxysilane in 12 parts of ethanol, mix well, and then add 20 parts of hydrochloric acid aqueous solution (concentration of 0.4 wt%) dropwise at 55°C for 1 hour. After heating to 70°C and reacting for 3 hours, remove the solvent to obtain a low-viscosity silicone resin precursor.

[0061] 2. Dissolve 12 parts of acetylferrocene in isopropanol, add 6 parts of tetrabutyl titanate solution dropwise at 45°C for 0.5 h, and continue the reaction for 4 h after the addition is complete. Cool down and crystallize to obtain the ligand compound of acetylferrocene and titanium atoms.

[0062] 3. Dissolve 100 parts of low-viscosity silicone resin precursor, 30 parts of acetylferrocene and heteroatom ligand compound in isopropanol, react at 75°C for 6 hours, remove the solvent, and obtain titanium atom modified silicone resin.

[0063] Example 3:

[0064] 1. Dissolve 10 parts of methyltrimethoxysilane, 12 parts of vinyltriethoxysilane and 10 parts of diphenyldimethoxysilane in 14 parts of isopropanol, mix well, and then add 21 parts of acetic acid aqueous solution (concentration of 0.3wt%) dropwise at 50°C for 0.75 h. After heating to 70°C and reacting for 2.5 h, remove the solvent to obtain a low-viscosity silicone resin precursor.

[0065] 2. Dissolve 12 parts of 1,1'-diacetylferrocene in ethyl acetate, add 2 parts of n-propanol hafnium solution dropwise at 55°C for 0.35 h, and continue the reaction for 4.5 h after the addition is complete. Cool down and crystallize to obtain ligand compounds of 1,1'-diacetylferrocene and hafnium atoms.

[0066] 3. Dissolve 100 parts of low-viscosity silicone resin precursor, 30 parts of 1,1'-diacetylferrocene and hafnium atoms in tetrahydrofuran, react at 75°C for 5 h, remove the solvent, and obtain hafnium atom modified silicone resin.

[0067] Example 4:

[0068] 1. Dissolve 20 parts of methyltrimethoxysilane and 20 parts of diphenyldimethoxysilane in 20 parts of tetrahydrofuran, mix evenly, and then add 40 parts of oxalic acid aqueous solution (concentration of 0.25wt%) dropwise at 55℃ for 1 hour. After heating to 60℃ and reacting for 4 hours, remove the solvent to obtain a low-viscosity silicone resin precursor.

[0069] 2. Dissolve 12 parts of acetylferrocene in DMF, add 5 parts of n-propoxide zirconium solution dropwise at 45°C for 0.5 h, and continue the reaction for 5 h after the addition is complete. Cool down and crystallize to obtain acetylferrocene ligand compound with zirconium atoms.

[0070] 3. Dissolve 100 parts of low-viscosity silicone resin precursor and 40 parts of acetylferrocene and zirconium atom ligand compound in isopropanol, react at 70°C for 6 hours, remove the solvent, and obtain zirconium atom modified silicone resin.

[0071] Example 5:

[0072] 1. Dissolve 30 parts of phenyltrimethoxysilane and 10 parts of methylphenyldimethoxysilane in 10 parts of acetone, mix well, and then add 30 parts of carbonic acid aqueous solution (concentration of 0.3wt%) dropwise at 45°C for 0.8 h. After heating to 70°C and reacting for 2 h, remove the solvent to obtain a low-viscosity silicone resin precursor.

[0073] 2. Dissolve 14 parts of acetylferrocene in ethanol, add 7 parts of tetrabutyl titanate solution dropwise at 45°C for 0.25 h, and continue the reaction for 4 h after the addition is complete. Cool down and crystallize to obtain the ligand compound of acetylferrocene and titanium atoms.

[0074] 3. Dissolve 100 parts of low-viscosity silicone resin precursor, 30 parts of acetylferrocene and titanium atom ligand compound in isopropanol, react at 90℃ for 6 h, remove the solvent, and obtain titanium atom modified silicone resin.

[0075] This invention also proposes a method for preparing a high-temperature resistant adhesive based on heteroatom-modified silicone resin prepared by the above method, comprising the following steps:

[0076] (1) A mixed filler with uniform particle size is obtained by ball milling reinforcing agent, dispersant, sintering aid and carbon source; the carbon source is carbon nanotube, graphite powder, carbon fiber, graphene or biomass carbon source; the preparation method of biomass carbon source is: placing biomass material in hydrothermal reactor and hydrothermally reacting at 180-350℃ for 24-48h to obtain biomass carbon source, the biomass material is at least one of rice husk, coconut shell, durian peel and straw; the sintering aid is at least one of zinc borate, AlN and B4C, the dispersant is at least one of hollow glass microspheres, fumed silica and hollow phenolic microspheres; the reinforcing agent is at least one of glass fiber, carbon fiber, carbon black, SiC, ZrB2, TiB2 and HfB2.

[0077] (2) The mixed filler is mechanically mixed with the heteroatom modified silicone resin matrix.

[0078] (3) After mixing evenly, add organic solvent C and coupling agent, and stir to obtain hybrid silicone resin-based high-temperature resistant adhesive; the coupling agent is at least one of γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, and γ-(methacryloyloxy)propyltrimethoxysilane; the organic solvent C is at least one of ethanol, isopropanol, and acetone.

[0079] Examples 6-10 illustrate the application of heteroatom-modified silicone resins in high-temperature adhesives.

[0080] Example 6:

[0081] (1) Place 15 parts of rice husk in a hydrothermal reactor and hydrothermally react at 180℃ for 48h to obtain biomass carbon source. Then, ball mill 7 parts of silicon powder, 18 parts of fumed silica, 6 parts of zinc borate, 25 parts of SiC and 8 parts of biomass carbon source to obtain a mixed filler with uniform particle size.

[0082] (2) The mixed filler was mechanically mixed with 50 parts of zirconium atom-modified silicone resin matrix;

[0083] (3) After mixing evenly, add 4 parts of γ-aminopropyltriethoxysilane and 20 parts of ethanol and stir to obtain zirconium hybrid silicon resin-based high-temperature resistant adhesive.

[0084] Example 7:

[0085] (1) Place 14 parts of coconut shell in a hydrothermal reactor and hydrothermally react at 260℃ for 36h to obtain biomass carbon source. Then, ball mill 8 parts of silicon powder, 20 parts of phenolic microspheres, 7 parts of AlN, 24 parts of ZrB2 and 7 parts of biomass carbon source to obtain a mixed filler with uniform particle size.

[0086] (2) The mixed filler was mechanically mixed with 40 parts of titanium atom modified silicone resin matrix;

[0087] (3) After mixing evenly, add 3 parts of γ-glycidyl oxypropyltrimethoxysilane and 15 parts of ethanol and stir to obtain titanium hybrid silicone resin-based high-temperature resistant adhesive.

[0088] Example 8:

[0089] (1) Place 18 parts of straw in a hydrothermal reactor and hydrothermally react at 350℃ for 24 hours to obtain biomass carbon source. After ball milling 9 parts of carbon fiber powder, 20 parts of phenolic microspheres, 8 parts of zinc borate, 27 parts of HfB2 and 9 parts of biomass carbon source, a mixed filler with uniform particle size is obtained.

[0090] (2) The mixed filler was subjected to strong mechanical mixing with 60 parts of hafnium atom-modified silicone resin matrix;

[0091] (3) After mixing evenly, add 5 parts of γ-(methacryloyloxy)propyltrimethoxysilane and 20 parts of acetone and stir to obtain hafnium hybrid silicone resin-based high-temperature resistant adhesive.

[0092] Example 9:

[0093] (1) Place 16 parts of durian peel in a hydrothermal reactor and hydrothermally react at 240℃ for 48h to obtain biomass carbon source. Then, ball mill 7 parts of silicon powder, 18 parts of fumed silica, 6 parts of B4C, 25 parts of TiB2 and 9 parts of biomass carbon source to obtain a mixed filler with uniform particle size.

[0094] (2) The mixed filler was mechanically mixed with 50 parts of titanium atom modified silicone resin matrix;

[0095] (3) After mixing evenly, add 4 parts of γ-aminopropyltriethoxysilane and 20 parts of isoethanol and stir to obtain titanium hybrid silicone resin-based high-temperature resistant adhesive.

[0096] Example 10:

[0097] (1) Place 15 parts of coconut shell in a hydrothermal reactor and hydrothermally react at 280℃ for 24h to obtain biomass carbon source. Then, ball mill 7 parts of glass fiber, 20 parts of fumed silica, 8 parts of AlN, 20 parts of ZrB2 and 8 parts of biomass carbon source to obtain a mixed filler with uniform particle size.

[0098] (2) The mixed filler was mechanically mixed with 45 parts of zirconium atom-modified silicone resin matrix;

[0099] (3) After mixing evenly, add 5 parts of γ-glycidyl etheroxypropyltrimethoxysilane and 18 parts of isoethanol and stir to obtain zirconium hybrid silicone resin-based high-temperature resistant adhesive.

[0100] Example 11:

[0101] (1) 16 parts carbon nanotubes, 8 parts glass fiber, 19 parts fumed silica, 9 parts AlN and 21 parts ZrB2 were ball-milled to obtain a mixed filler with uniform particle size.

[0102] (2) The mixed filler was mechanically mixed with 48 parts of zirconium atom-modified silicone resin matrix;

[0103] (3) After mixing evenly, add 6 parts of γ-(methacryloyloxy)propyltrimethoxysilane and 17 parts of acetone and stir to obtain zirconium hybrid silicone resin-based high-temperature resistant adhesive.

[0104] Example 12:

[0105] (1) 18 parts graphite powder, 9 parts carbon fiber, 20 parts hollow phenolic microspheres, 12 parts zinc borate, and 24 parts ZrB2 were ball-milled to obtain a mixed filler with uniform particle size.

[0106] (2) The mixed filler was mechanically mixed with 52 parts of zirconium atom-modified silicone resin matrix;

[0107] (3) After mixing evenly, add 7 parts of γ-glycidyl etheroxypropyltrimethoxysilane and 20 parts of isoethanol and stir to obtain zirconium hybrid silicone resin-based high-temperature resistant adhesive.

[0108] Example 13:

[0109] (1) 24 parts carbon fiber, 10 parts SiC, 22 parts hollow glass microspheres, 8 parts B4C, and 20 parts TiB2 were ball-milled to obtain a mixed filler with uniform particle size.

[0110] (2) The mixed filler was mechanically mixed with 50 parts of titanium atom modified silicone resin matrix;

[0111] (3) After mixing evenly, add 5 parts of γ-aminopropyltriethoxysilane and 18 parts of ethanol and stir to obtain titanium hybrid silicone resin-based high-temperature resistant adhesive.

[0112] Example 14:

[0113] (1) 18 parts graphene, 10 parts carbon black, 21 parts fumed silica, 7 parts AlN, and 22 parts HfB2 were ball-milled to obtain a mixed filler with uniform particle size.

[0114] (2) The mixed filler was subjected to strong mechanical mixing with 54 parts of hafnium atom-modified silicone resin matrix;

[0115] (3) After mixing evenly, add 8 parts of γ-glycidyl etheroxypropyltrimethoxysilane and 21 parts of isoethanol and stir to obtain hafnium hybrid silicone resin-based high-temperature resistant adhesive.

[0116] Analysis and Testing

[0117] The synthetic route of this invention is shown in the following steps:

[0118] Step 1: Synthesis of methylphenyl silicone resin precursor

[0119]

[0120] Step 2: Synthesis of acetylferrocene

[0121]

[0122] Step 3: Synthesize intermetallic compounds encapsulating zirconium atoms with ferrocene via chelation coordination.

[0123]

[0124] Step 4: Introduce intermetallic compounds into the polymer backbone through π-π stacking to synthesize zirconium hybrid silicon resin, improving heat resistance, while simultaneously growing SiC nanowires in situ at high temperature.

[0125]

[0126] Figure 1-6 The results are related to the test in Example 1.

[0127] Figure 1 The infrared spectrum of the methylphenyl silicone resin precursor in step 1 is shown, with a peak at 3075 cm⁻¹. -1 and 2970cm -1 The absorption peak at 1435 cm⁻¹ is caused by methyl groups; all samples show an absorption peak at 1435 cm⁻¹. -1 698cm -1 903cm -1 and 1429cm -1 1596cm -1 The nearby peaks all belong to phenyl groups, while the peak at 3408 cm⁻¹... -1 The peak at 1024-1127 cm⁻¹ represents the Si-OH peak where no condensation reaction has occurred. Meanwhile, the peaks at 1024-1127 cm⁻¹... -1 The characteristic peak at the location represents Si-O-Si, indicating that the target product, the methylphenyl silicone resin precursor, has been successfully synthesized.

[0128] Figure 2The infrared spectrum of the zirconium hybrid silicone resin in step 4, after modification with an intermetallic compound encapsulating zirconium atoms by ferrocene, shows a higher infrared spectrum compared to the methylphenyl silicone resin precursor in step 1, at 1600 cm⁻¹. -1 The stretching vibration peak of the C=O basis was clearly observed at 930 cm⁻¹. -1 The stretching vibration peaks of O-Zr-O were clearly observed at 1400-1600 cm⁻¹. -1 The multiple peaks represent the C=C stretching vibration of the cyclopentadiene ring in ferrocene, indicating that the target product was successfully synthesized.

[0129] Figure 3 The XRD patterns of the methylphenyl silicone resin precursor in step 1 and the residual components after high-temperature ablation of the zirconium hybrid silicone resin in step 4 are shown. It can be seen that the methylphenyl silicone resin precursor in step 1 has no obvious characteristic peaks, while the zirconium hybrid silicone resin in step 4 generates catalyst components such as FeC and ZrO2 during pyrolysis and shows obvious SiC characteristic peaks. This indicates that the target product was successfully synthesized and has a significant promoting effect on the growth of SiC nanowires.

[0130] Figure 4 The XPS spectrum of the residual components after high-temperature ablation of the zirconium hybrid silicon resin in step 4 is shown. Further analysis of the residual components after high-temperature ablation revealed the presence of five elements: carbon, silicon, oxygen, zirconium, and iron in the hybrid silicon resin, which is consistent with the results of infrared and XRD tests. Furthermore, there are obvious SiC, SiO, CO, FeC, ZrO, and ZrC bonds, which represent the catalyst, silicon source, and carbon source in the SiC nanowire growth process, proving that the target product was successfully synthesized.

[0131] like Figure 5 As shown, compared with the methylphenyl silicone resin precursor, the heteroatom-modified silicone resin has a higher T... 5％ The temperature was increased from 422℃ to 573℃, and the residual weight at 1000℃ was 87.98wt%, while the residual weight of pure silicone resin at 1000℃ was only 78.34wt%, indicating that the heat resistance of the silicone resin matrix modified with heteroatoms was greatly improved.

[0132] Depend on Figure 6 As shown, at 1600℃, a large number of SiC nanowire structures are generated in zirconium-hybridized silicon resin through zirconium atom-assisted catalysis, thereby improving the strength of the residue at high temperature.

[0133] Figure 7-14 This analysis and testing focused on the performance of the zirconium hybrid silicon resin-based high-temperature resistant adhesive and the self-growth reinforcement mechanism of SiC nanowires in Example 6.

[0134] Figure 7The figures show the pyrolysis curves of the zirconium hybrid silicone resin-based high-temperature resistant adhesive under air and nitrogen atmospheres. The residual weight of the high-temperature resistant adhesive at 1000℃ under nitrogen atmosphere is 88.9 wt%, and the residual weight of the high-temperature resistant adhesive at 1000℃ under air atmosphere is 95.1 wt%, indicating that the prepared hybrid silicone resin-based high-temperature resistant adhesive has high heat resistance under different atmospheres.

[0135] from Figure 8 It can be seen that the high-temperature bonding strengths at 1600℃ for 1-3 hours are 20.72 MPa, 21.91 MPa, and 19.72 MPa, respectively. This indicates that the in-situ self-grown SiC nanowires catalyzed by zirconium and iron atoms have a significant reinforcing effect on the high-temperature adhesive, greatly improving its high-temperature bonding performance.

[0136] from Figure 9 It can be seen that a large number of SiC nanowires are grown in situ on the surface of the biomass carbon source, and their growth morphology is uniform and stable.

[0137] from Figure 10 It is evident that the growth mechanism of SiC nanowires follows a solid-gas-liquid growth mechanism. During the pyrolysis of zirconium-hybrid silicon resin, a heterogeneous catalyst is generated in situ. The synergistic catalytic effect of zirconium and iron atoms improves the growth efficiency of SiC nanowires and provides some repair for cracks generated during pyrolysis. Simultaneously, the fracture, pull-out, and crack deflection of SiC nanowires dissipate additional energy (see...). Figure 11-13 ), and as Figure 14 The crack shown terminates in the region where a large number of SiC nanowires grow, which significantly improves its high-temperature bonding performance.

[0138] Figure 15-16 Analysis and testing were conducted on the performance of the titanium hybrid silicon resin-based high-temperature resistant adhesive and the growth morphology of SiC nanowires in Example 7.

[0139] from Figure 15 It can be seen that the high-temperature bonding strengths at 1600℃ for 1-3 hours were 16.63 MPa, 18.51 MPa, and 15.32 MPa, respectively. This indicates that the in-situ self-grown SiC nanowires, catalyzed by the synergistic effect of titanium and iron atoms, significantly enhanced the high-temperature adhesive, greatly improving its high-temperature bonding performance. Furthermore, from... Figure 16 It can be seen that the aspect ratio of SiC nanowires grown by the synergistic catalysis of titanium and iron atoms is relatively low, so the reinforcing effect is lower than that of zirconium hybrid silicon resin-based high-temperature adhesive.

Claims

1. A method for preparing a heteroatom-modified silicone resin, comprising the following steps:

1. Dissolve trifunctional siloxane monomers and difunctional siloxane monomers in organic solvent A, mix them evenly, and then add acidic aqueous solution dropwise at 45-55℃ for 0.5-1h. Raise the temperature to 60-70℃ and react for 2-4h. Remove the solvent to obtain a low-viscosity silicone resin precursor.

2. Dissolve acylferrocene in organic solvent B, and add a heteroatom solution dropwise at 45-55℃ for 0.25-0.5 h. After the addition is complete, continue the reaction for 4-6 h, cool down, crystallize and purify to obtain the acylferrocene ligand compound with heteroatom; the heteroatom solution is boric acid, tetrabutyl titanate, zirconium n-propoxide or hafnium n-propoxide.

3. Dissolve the low-viscosity silicone resin precursor, acyl ferrocene and heteroatom ligand compound in alcohol solvent A, react at 70-90℃ for 4-6 hours, remove the solvent, and obtain heteroatom modified silicone resin.

2. The method for preparing a heteroatom-modified silicone resin according to claim 1, characterized in that, The trifunctional siloxane monomer mentioned in step one is at least one of methyltrimethoxysilane, phenyltrimethoxysilane, and vinyltriethoxysilane; the difunctional siloxane monomer is at least one of diphenyldimethoxysilane, dimethyldimethoxysilane, and methylphenyldimethoxysilane.

3. The method for preparing a heteroatom-modified silicone resin according to claim 1, characterized in that, The mass ratio of the trifunctional siloxane monomer, difunctional siloxane monomer, organic solvent A, and acidic aqueous solution in step one is 1-3:1-2:1-2:2-3.

4. The method for preparing a heteroatom-modified silicone resin according to claim 1, characterized in that, The acyl ferrocene mentioned in step two is at least one of formyl ferrocene, acetyl ferrocene, butyryl ferrocene, 1,1'-diformyl ferrocene, 1,1'-diacetyl ferrocene, and 1,1'-dibutyryl ferrocene; the mass ratio of acyl ferrocene to heteroatom solution is 2-6:

1.

5. The method for preparing a heteroatom-modified silicone resin according to claim 1, characterized in that, The acylferrocene and heteroatom ligand compound mentioned in step three is 20-40 wt% of the low-viscosity silicone resin precursor.

6. The method for preparing a heteroatom-modified silicone resin according to claim 1, characterized in that, The acidic aqueous solution mentioned in step one is at least one of hydrochloric acid, acetic acid, oxalic acid, and carbonic acid, and the concentration of the acidic aqueous solution is 0.1-0.4 wt%.

7. The method for preparing a heteroatom-modified silicone resin according to claim 1, characterized in that, The organic solvent A is at least one of tetrahydrofuran, ethanol, isopropanol, and acetone; the organic solvent B is at least one of isopropanol, DMF, ethyl acetate, and ethanol.

8. A method for preparing a high-temperature resistant adhesive, characterized in that, Using the heteroatom-modified silicone resin prepared by the method of claim 1 as a raw material, the process includes the following steps: (1) The reinforcing agent, dispersant, sintering aid and carbon source are ball-milled to obtain a mixed filler with uniform particle size; (2) The mixed filler and the heteroatom-modified silicone resin matrix are subjected to strong mechanical mixing; (3) After mixing evenly, add organic solvent C and coupling agent, and stir to obtain hybrid silicone resin-based high-temperature resistant adhesive; The carbon source is carbon nanotubes, graphite powder, carbon fiber, graphene, or biomass carbon source.

9. The method for preparing a high-temperature resistant adhesive according to claim 8, characterized in that, The method for preparing the biomass carbon source is as follows: placing the biomass material in a hydrothermal reactor and reacting it at 180-350℃ for 24-48 hours to obtain the biomass carbon source. The biomass material is at least one of rice husk, coconut shell, durian peel, and straw.

10. The method for preparing a high-temperature resistant adhesive according to claim 8, characterized in that, The sintering aid is at least one of zinc borate, AlN, and B4C, and the organic solvent C is at least one of ethanol, isopropanol, and acetone.

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