An aromatic schiff base silane modified ablative resistant resin matrix material, its preparation method and use

Abstract

The application provides an aromatic Schiff base silane modified ablative resistant resin matrix material and a preparation method and application thereof, and belongs to the field of thermal protection materials. A silane coupling agent containing a hydroxyl group substituted aromatic Schiff base structure is synthesized, and a certain amount of the coupling agent is added to raw materials of traditional silane and a thermosetting resin, so that the compatibility of the organic silicon and the thermosetting resin is significantly improved. The material has excellent ablative resistance, has a wide application prospect in the field of thermal protection materials, and is suitable for preparing a protective material of a structural component and a structural component which needs to withstand a high-temperature gas and an aerodynamic heat flow scouring harsh environment in an aircraft and related equipment devices.

Description

Technical Field

[0001] This invention belongs to the field of thermal protection materials, specifically relating to an aromatic Schiff base silane-modified ablation-resistant resin matrix material, its preparation method, and its applications. Background Technology

[0002] Thermal protection materials are crucial for the safe operation of spacecraft in extreme environments. With the rapid development of flight technology, the thermal environments faced by new-generation spacecraft are becoming increasingly demanding.

[0003] Resin-based ablation-resistant heat-resistant materials have high heat protection efficiency and are currently the most widely used type of heat-resistant material. Phenolic resin, due to its simple molding process, good heat resistance, high mechanical strength, and outstanding instantaneous high-temperature ablation resistance, is often used as an anti-ablation heat-resistant structure and heat-resistant layer matrix. Composite materials prepared with phenolic resin as the matrix play a very important role in thermal protection composite materials for aircraft.

[0004] Although traditional phenolic resin-based composite materials have good ablation performance and high material strength, their fracture elongation and ablation residue are relatively low. Moreover, the carbonization products are difficult to graphitize, and their oxidation resistance is poor. During flight, carbon layer erosion may occur, making it difficult for the materials to meet the high heat resistance, oxidation resistance and overload resistance requirements of future aircraft that are designed for high Mach, high maneuverability and multi-airspace development.

[0005] Polysiloxanes are polymers with excellent thermal stability and ablation properties, and have been widely used to modify phenolic resins to improve their flame retardancy or ablation performance in aerobic environments. Organosilicones, through blending or chemical bonding into the resin network, can generate in-situ silica inorganic liquid films and silicon carbide ceramics during ablation and carbonization, enhancing the material's resistance to thermomechanical and chemithermal oxidation losses on the ablated surface carbon layer. However, the solubility parameters of polysiloxanes and organic polymers differ significantly, and the compatibility between organosilicones and phenolic resins is poor, often leading to macroscopic phase separation in hybrid resin systems.

[0006] To address the poor compatibility between organosilicon and phenolic resin, the most common method is to use silane coupling agents. However, the molecular chain structures of commonly used KH560 and KH550 silane coupling agents contain long-chain alkanes, which are easily degraded by heat. Furthermore, as the amount of coupling agent added increases, the content of benzene rings in the crosslinking network gradually decreases. This affects the carbonization performance of the phenolic resin during ablation, leading to a deterioration in ablation performance. Summary of the Invention

[0007] To overcome the aforementioned problems in existing technologies, the present invention aims to design a novel multifunctional silane coupling agent based on the molecular structure of hybrid resins, thereby improving the poor compatibility between organosilicon and phenolic resins. Studies have found that hydroxyl-substituted Salenyl Schiff bases can react with phenolic resins under suitable conditions. Therefore, the present invention designs and synthesizes a silane coupling agent containing a hydroxyl-substituted aromatic Schiff base structure, where the hydroxyl-substituted aromatic group provides a reaction site with the phenolic resin.

[0008] This invention provides a Schiff base silane coupling agent modified resin, which is a composite material prepared from the following components in parts by weight: 0.01-50 parts Schiff base silane coupling agent, 100-500 parts thermosetting resin, 100-500 parts alkoxysilane, 0-50 parts organic acid, and 0-50 parts water.

[0009] Further, the Schiff base silane coupling agent modified resin is a composite material prepared from the following components in parts by weight: 10-20 parts Schiff base silane coupling agent, 140-160 parts thermosetting resin, 100-200 parts alkoxysilane, 0-10 parts organic acid, and 0-44.85 parts water; preferably, it is a composite material prepared from the following components in parts by weight: 14.41 parts Schiff base silane coupling agent, 150 parts thermosetting resin, 140 parts alkoxysilane, 0-9.74 parts organic acid, and 44.85 parts water;

[0010] The thermosetting resin is a phenolic resin or a modified phenolic resin, preferably a boron phenolic resin or a modified boron phenolic resin; the alkoxysilane is methyltriethoxysilane, isobutyltriethoxysilane, γ-aminopropyltriethoxysilane, trimekoxysilane, or dialkoxysilane; the organic acid is acetic acid, formic acid, propionic acid, butyric acid, citric acid, lactic acid, malic acid, or tartaric acid.

[0011] Furthermore, the Schiff base silane coupling agent modified resin is a composite material prepared from the following components in parts by weight: 14.41 parts Schiff base silane coupling agent, 150 parts thermosetting resin, 140 parts alkoxysilane, 3.90-9.74 parts organic acid, and 44.85 parts water.

[0012] Furthermore, the Schiff base silane coupling agent modified resin is a composite material prepared from the following components in parts by weight: 14.41 parts Schiff base silane coupling agent, 150 parts thermosetting resin, 140 parts alkoxysilane, 3.90 parts organic acid, and 44.85 parts water.

[0013] Furthermore, the Schiff base silane coupling agent is a product obtained by reacting an aminoalkoxysilane with salicylaldehyde or its derivative;

[0014] The mass ratio of the aminoalkoxysilane to salicylaldehyde or its derivative is 10:(3-5), preferably 10:4.41;

[0015] The aminoalkoxysilane is any one or a mixture of two or more of 3-aminopropyltriethoxysilane, aminopropyltrimethoxysilane, bis(tert-butylamino)silane, and 4-anilinetriethoxysilane.

[0016] Further, the Schiff base silane coupling agent is prepared by the following method: reacting an aminoalkoxysilane with salicylaldehyde or its derivative in an organic solvent to obtain the Schiff base silane coupling agent; wherein the reaction temperature is 40-70℃ and the reaction time is 1-4 hours; the mass ratio of the aminoalkoxysilane to the organic solvent is 10:(50-200).

[0017] Preferably, the organic solvent is ethanol, the reaction temperature is 60°C, and the reaction time is 2 hours; the mass ratio of the aminoalkoxysilane to the organic solvent is 10:100.

[0018] The present invention also provides a method for preparing the above-mentioned Schiff base silane coupling agent modified resin, the method comprising the following steps:

[0019] (1) Thermosetting resin, alkoxysilane, Schiff base silane coupling agent, water and organic acid are added to an organic solvent to react. After the reaction is completed, a resin solution is obtained. The organic solvent is removed to obtain an intermediate.

[0020] (2) Solidify the intermediate to obtain the final product.

[0021] Further, the organic solvents mentioned in steps (1) and (2) are alcohol solvents; the reaction temperature in step (1) is 80-100℃, the time is 2-8 hours, and the mass ratio of thermosetting resin to organic solvent is 150:(100-200);

[0022] Preferably, the organic solvent in steps (1) and (2) is ethanol; the reaction temperature in step (1) is 80°C and the reaction time is 4 hours.

[0023] This invention also provides the use of the above-mentioned Schiff base silane coupling agent modified resin in thermal protection materials, ablation-resistant materials, and fireproof materials.

[0024] Furthermore, the thermal protection materials include aircraft thermal protection structural materials and engine thermal protection materials.

[0025] This invention synthesizes a silane coupling agent containing a hydroxyl-substituted aromatic Schiff base structure. Using traditional silanes and thermosetting resins as raw materials, the compatibility between organosilicon and thermosetting resins is significantly improved by adding a certain amount of coupling agent. The material of this invention exhibits excellent ablation resistance and has broad application prospects in the field of thermal protection materials. It is suitable for preparing structural components and protective materials for aircraft and related equipment that must withstand harsh environments such as high-temperature exhaust gases and aerodynamic heat flow.

[0026] The Schiff base silane coupling agent modified boron phenolic resin prepared by this invention exhibits significantly improved ablation resistance and heat resistance. Specifically, the Schiff base silane coupling agent modified boron phenolic resin obtained in Example 4 demonstrates the best ablation resistance, while the Schiff base silane coupling agent modified boron phenolic resin obtained in Example 5 exhibits the best heat resistance. This invention's Schiff base silane coupling agent modified boron phenolic resin has broad application prospects in the field of thermal protection materials, and is suitable for preparing protective materials for structural components and related equipment in aircraft and related devices that must withstand harsh environments such as high-temperature exhaust gases and aerodynamic heat flow.

[0027] Obviously, based on the above description of the present invention, and according to common technical knowledge and conventional methods in the field, various other modifications, substitutions or alterations can be made without departing from the basic technical concept of the present invention.

[0028] The following detailed embodiments further illustrate the above-described content of the present invention. However, this should not be construed as limiting the scope of the present invention to the following examples. All technologies implemented based on the above-described content of the present invention fall within the scope of the present invention. Attached Figure Description

[0029] Figure 1 Infrared spectra of boron phenolic resin modified with Schiff base coupling agent: (a) uncured, (b) cured, and (c) cured; XPS spectra of Si2p and B1s of the modified resin after curing; (f) 29Si solid-state NMR spectrum of the uncured resin; SEM morphology of the brittle fracture surface and its Si elemental mapping; (g) SBPR. 50-4 (h)SBPR B50-4 .

[0030] Figure 2 The images show (a) the SAXS spectrum and (b) the XRD spectrum of the cured resin.

[0031] Figure 3 The image shows the height contour (ah) and 3D morphology (ip) of the sample surface after 30 s ablation: (a, i) pure boron phenolic resin, (b, j) SBPR. B50-0 , (c, k)SBPR 50-0, (d, l)SBPR 50-1 , (e, m)SBPR 50-2 , (f, n)SBPR 50-3 , (g, o)SBPR 50-4 , (h, p)SBPR B50-4 (q) Profile outline, (r) Line ablation rate distribution and (s) Width of ablation retreat region.

[0032] Figure 4 Linear ablation rate (a) and mass ablation rate (b) of the sample after 30 s of ablation.

[0033] Figure 5 The thermogravimetric curves (a, c) and the residual weight at 800℃ (b, d) of each hybrid resin after curing are shown. Detailed Implementation

[0034] Boron phenolic resin (BPR): Shaanxi Taihang Flame Arrestor Company, THC-400 boron phenolic resin, gel speed 70~100s / 200℃, free phenol content less than 7%, yellow blocky.

[0035] Methyltriethoxysilane (MTOS); 3-aminopropyltriethoxysilane (APTES); Salicylic aldehyde (SD);

[0036] Ethanol.

[0037] The raw materials and equipment used in this invention are all known products, obtained by purchasing commercially available products.

[0038] Table 1 Raw material formulations for each sample

[0039]

[0040] Example 1: Schiff base silane coupling agent modified boron phenolic resin (SBPR) of the present invention 50-0 Preparation of )

[0041] Step 1. Preparation of Schiff base silane coupling agent (ATSD)

[0042] 10 g (0.045 mol) of 3-aminopropyltriethoxysilane, 4.41 g (0.036 mol) of salicylaldehyde, and 100 g of ethanol were added to a flask. The oil bath was heated to 60 °C and kept at this temperature for 2 hours under an inert atmosphere to obtain a bright yellow ethanol solution containing a Schiff base silane coupling agent. An excess of 3-aminopropyltriethoxysilane was used to ensure complete reaction of salicylaldehyde in the system. The remaining 3-aminopropyltriethoxysilane in the system also played a coupling role in subsequent reactions.

[0043] Step 2. The Schiff base silane coupling agent modified boron phenolic resin (SBPR) of the present invention50-0 Preparation of )

[0044] Add 150g of boron phenolic resin and 200g of ethanol to a flask and stir at room temperature until the boron phenolic resin is completely dissolved. Then add 140g of methyltriethoxysilane and stir until evenly dispersed. Finally, add the ethanol solution of the Schiff base silane coupling agent prepared in step 1 of Example 1. Heat the oil bath to 80°C and react for 4 hours under an inert atmosphere to obtain the resin solution.

[0045] After the reaction was completed, the resin solution was concentrated by rotary evaporation and treated in a vacuum oven at 60°C for 12 hours to remove the solvent from the resin, thereby obtaining boron phenolic resin powder modified with Schiff base silane coupling agent.

[0046] The obtained modified boron phenolic resin powder was molded and cured. The curing process was as follows: 110℃ without pressure, held for 30 min; 110℃ to 140℃, heating rate 5℃ / min; 140℃, held for 30 min, and gradually increased pressure to 12-15 MPa; 140℃ to 180℃, heating rate 5℃ / min, maintaining pressure 12-15 MPa; 180℃, held for 2 h, maintaining pressure 12-15 MPa; 180℃ to 200℃, heating rate 5℃ / min, maintaining pressure 12-15 MPa; 200℃, held for 1 h, maintaining pressure 12-15 MPa; finally, maintaining pressure 12-15 MPa and naturally cooling to room temperature, thus obtaining the Schiff base silane coupling agent modified boron phenolic resin ablation resistant material.

[0047] Examples 2-3: Schiff base silane coupling agent modified boron phenolic resin of the present invention (Example 2 SBPR) 50-1 Example 3SBPR 50-2 Preparation of )

[0048] Take 150g of boron phenolic resin and SBPR according to Table 1 50-1 SBPR 50-2 The corresponding amount of ethanol in the sample formulation was added to the flask and stirred at room temperature until the boron phenolic resin was completely dissolved. Then, 140g of methyltriethoxysilane was added and stirred until evenly dispersed. Finally, the Schiff base-containing silane coupling agent solution prepared in step 1 of Example 1 was added. The oil bath was heated to 80°C, and under an inert atmosphere, a deionized water mixture solution (the amount added is shown in Table 1) was added dropwise to the flask through a constant pressure dropping funnel. After the addition was complete, the reaction was continued at 80°C for 4 hours to obtain the resin solution.

[0049] After the reaction was completed, the resin solution was concentrated by rotary evaporation and treated in a vacuum oven at 60°C for 12 hours to remove the solvent from the resin, thereby obtaining boron phenolic resin powder modified with Schiff base silane coupling agent.

[0050] The material is molded and cured using the same curing process as in Example 1, resulting in the Schiff base silane coupling agent modified boron phenolic resin ablation resistant material SBPR. 50-1 SBPR 50-2 .

[0051] Examples 4-5: Schiff base silane coupling agent modified boron phenolic resin of the present invention (Example 4 SBPR) 50-3 Example 5 SBPR 50-4 Preparation of )

[0052] Add 150g of boron phenolic resin and 100g of ethanol to a flask and stir at room temperature until the boron phenolic resin is completely dissolved. Then add 140g of methyltriethoxysilane and stir until evenly dispersed. Finally, add the ethanol solution of the Schiff base silane coupling agent prepared in step 1 of Example 1. Heat the oil bath to 80°C and add a mixture of acetic acid (addition amount corresponds to Table 1) and deionized water (44.85g of deionized water) dropwise to the flask through a constant pressure dropping funnel under an inert atmosphere. After the addition is complete, continue the reaction at 80°C for 4 hours to obtain the resin solution.

[0053] After the reaction was completed, the resin solution was concentrated by rotary evaporation and treated in a vacuum oven at 60°C for 12 hours to remove the solvent from the resin, thereby obtaining boron phenolic resin powder modified with Schiff base silane coupling agent.

[0054] The material is molded and cured using the same curing process as in Example 1, resulting in the Schiff base silane coupling agent modified boron phenolic resin ablation resistant material SBPR. 50-3 SBPR 50-4 .

[0055] Example 6: Preparation of the Schiff base silane coupling agent of the present invention

[0056] 10 g (0.045 mol) of 3-aminopropyltriethoxysilane, 4.41 g (0.036 mol) of salicylaldehyde, and 100 g of ethanol were added to a flask. The oil bath was heated to 60 °C and kept at this temperature for 2 hours under an inert atmosphere to obtain a bright yellow ethanol solution containing a Schiff base silane coupling agent. An excess of 3-aminopropyltriethoxysilane was used to ensure complete reaction of salicylaldehyde in the system. The remaining 3-aminopropyltriethoxysilane in the system also played a coupling role in subsequent reactions.

[0057] Example 7: Preparation of the Schiff base silane coupling agent of the present invention

[0058] 10 g (0.045 mol) of 3-aminopropyltriethoxysilane, 3.4 g (0.028 mol) of salicylaldehyde, and 50 g of ethanol were added to a flask. The oil bath was heated to 70 °C and kept at this temperature for 2 hours under an inert atmosphere to obtain a bright yellow ethanol solution containing a Schiff base silane coupling agent. An excess of 3-aminopropyltriethoxysilane was used to ensure complete reaction of salicylaldehyde in the system. The remaining 3-aminopropyltriethoxysilane in the system also played a coupling role in subsequent reactions.

[0059] Example 8: Preparation of the Schiff base silane coupling agent of the present invention

[0060] 10 g (0.045 mol) of 3-aminopropyltriethoxysilane, 4 g (0.036 mol) of salicylaldehyde, and 100 g of ethanol were added to a flask. The oil bath was heated to 65 °C and kept at this temperature for 2 hours under an inert atmosphere to obtain a bright yellow ethanol solution containing a Schiff base silane coupling agent. An excess of 3-aminopropyltriethoxysilane was used to ensure complete reaction of salicylaldehyde in the system. The remaining 3-aminopropyltriethoxysilane in the system also played a coupling role in subsequent reactions.

[0061] The following is the method for preparing the control sample.

[0062] Comparative Example 1, Silane-modified boron phenolic resin (SBPR) B50-0 Preparation of )

[0063] 150g of boron phenolic resin, 150g of methyltriethoxysilane, and 300g of ethanol were added to a flask and stirred at room temperature until completely dissolved. The oil bath was heated to 80℃ and reacted under an inert atmosphere for 4 hours. After the reaction was complete, the solvent in the resin was removed by rotary evaporation and a vacuum oven to obtain silane-modified boron phenolic resin powder.

[0064] The material is molded and cured using the same curing process as in Example 1, resulting in a silane-modified boron phenolic resin ablation-resistant material (SBPR). B50-0 ).

[0065] Comparative Example 2, Silane-modified boron phenolic resin (SBPR) B50-4 Preparation of )

[0066] 150g of boron phenolic resin, 150g of methyltriethoxysilane, and 200g of ethanol were added to a flask and stirred at room temperature until completely dissolved. An oil bath was heated to 80°C, and a mixed solution of acetic acid and deionized water (9.74g acetic acid and 44.85g deionized water) was added dropwise to the flask through a constant-pressure dropping funnel under an inert atmosphere. After the addition was complete, the reaction was continued at 80°C for 4 hours. After the reaction was completed, the solvent in the resin was removed by rotary evaporation and a vacuum oven to obtain silane-modified boron phenolic resin powder.

[0067] The material is molded and cured using the same curing process as in Example 1, resulting in a silane-modified boron phenolic resin ablation-resistant material (SBPR). B50-4 ).

[0068] Comparative Example 3: Preparation of Cured Boron Phenolic Resin (BPR')

[0069] Boron phenolic resin powder (BPR) was used for compression molding and then cured. The curing process was the same as in Example 1, thus obtaining boron phenolic resin ablation resistant material (BPR').

[0070] The following experimental examples demonstrate the beneficial effects of the present invention.

[0071] Experimental Example 1: Structural Characterization of the Modified Boron Phenolic Resin of the Present Invention

[0072] I. Experimental Methods

[0073] Infrared spectroscopy test Figure 1 (ac) and 29Si solid-state NMR Figure 1 (f) Characterizing the structural changes of the modified resin before, during, and after curing. This was achieved using X-ray photoelectron spectroscopy (XPS). Figure 1 (d, e) characterize the structural differences of the modified resin after curing. The organosilicon phases and Si elemental distribution are characterized by scanning electron microscopy (SEM) morphology images of the brittle fracture surface of the cured resin and its mapping mode. Figure 1 (g, h).

[0074] SBPR 50-0 and SBPR 50-3 Small-angle X-ray diffraction (SAXS) tests were performed, and the experimental results are as follows: Figure 2 As shown in Figure a, X-ray diffraction (XRD) tests were performed on each cured resin, and the experimental results are as follows. Figure 2 As shown in b.

[0075] II. Experimental Results

[0076] Figure 1 a and Figure 1 In the infrared spectrum of the resin before and after curing, 1635 cm⁻¹ -1 The peak at -CH=N indicates the successful introduction of the Schiff base structure. (960 cm⁻¹) -1 and 910cm -1 The peaks at Si-O-Ph and Si-OB indicate that organosilicones covalently attach siloxanes to phenolic resins through reactions with phenolic and boron hydroxyl groups.

[0077] Figure 1 b 960cm -1The Si-O-Ph bond strength continuously weakens, indicating that there is some loss during the curing process. And at 1226 cm⁻¹... -1 The Ar-OH elution peak gradually weakens, indicating that as the curing reaction proceeds, the B-OH and Ph-OH in the system gradually react completely.

[0078] Figure 1 As can be seen in d, with the increase of deionized water / acetic acid and the decrease of ethanol, the relative content of Si-O-Si bonds in the Si element in the system gradually increases, from 32.3% in SBPR50-0 to 53.4% ​​in SBPR50-4, indicating that the degree of silane self-condensation in the system is continuously increasing.

[0079] Figure 1 e indicates that the B element in the cured resin participates in the resin curing process by forming BOC, BOB, and BO-Si forms. The appearance of BO-Si bonds further proves that organosilicon, through reaction with boron hydroxyl groups, covalently integrates siloxanes into the phenolic resin.

[0080] Figure 1 f indicates that as the amount of deionized water / acetic acid added increases and the amount of ethanol decreases, the number of ethoxy groups in the system continuously decreases, indicating that the degree of silane self-condensation increases.

[0081] contrast Figure 1 g and Figure 1 As can be seen, when the amount of deionized water / acetic acid added is the same as the amount of ethanol added, the addition of Schiff base coupling agent causes the organosilicon to undergo micron-level phase separation in the phenolic resin. Figure 1 h) transforms into a homogeneous system, and no obvious phase separation is observed.

[0082] Experimental results show that this invention can alter the degree of silane self-condensation within the system by adjusting the amounts of deionized water, acetic acid, and ethanol in the formulation. This invention continuously increases the degree of silane self-condensation by increasing the amounts of deionized water, acetic acid, and ethanol in the formulation. Simultaneously, the addition of a Schiff base coupling agent in this invention transforms the organosilicon in the system from a micron-scale phase separation to a homogeneous system, significantly improving the compatibility between organosilicon and boron phenolic resin, even when the degree of silane self-condensation within the system is not significantly different.

[0083] Figure 2 As can be seen, SBPR 50-0 The SAXS curve of the sample showed no scattering peaks, indicating the absence of microstructure; SBPR 50-3 The SAXS curve of the sample showed a weak scattering shoulder. Calculated using the Bragg formula (L=2π / q), the average distance between adjacent organosilicon phases was 14.3 nm. Figure 2As can be seen in b, there is a passivated amorphous diffraction peak around 10.7°, corresponding to the organosilicon phase; for SBPR without the addition of Schiff base coupling agent... B50-4 The sample showed a significant increase in peak intensity and a narrower peak shape, indicating a larger organosilicon phase size. The experimental results further demonstrate that the addition of Schiff base coupling in this invention can significantly improve the compatibility between organosilicon and boron phenolic resin.

[0084] Experimental Example 2: Test of the ablation performance of the modified boron phenolic resin of the present invention

[0085] I. Experimental Methods

[0086] According to the ablation resistance test standard GJB 323A-1996; heat flux density: 4000kW / m³ 2 Ablation time: 30s; ablation resistance test was conducted. Experimental results are as follows: Figure 3 (qs), Figure 4 And as shown in Table 2.

[0087] Table 2 Results of linear ablation rate and mass ablation rate for each cured resin

[0088]

[0089]

[0090] It can be seen that, compared with the cured boron phenolic resin (BPR') of Comparative Example 3 and the silane-modified boron phenolic resins of Comparative Examples 1 and 2, the linear ablation rate of the Schiff base silane coupling agent modified boron phenolic resins of Examples 3-5 of the present invention is significantly reduced. Among them, the Schiff base silane coupling agent modified boron phenolic resin of Example 4 has the lowest linear ablation rate and the best ablation resistance.

[0091] Experimental Example 3: Heat Resistance Test of the Modified Boron Phenolic Resin of the Present Invention

[0092] Thermogravimetric analysis (TG) was used to test the thermogravimetric curves of the cured samples under nitrogen (N2) and air (Air) atmospheres, and the residual weight at 800℃ was obtained. The experimental results are as follows: Figure 5 As shown in Table 3.

[0093] Table 3. Residual weight (%) of each cured resin at 800℃

[0094]

[0095] It can be seen that, regardless of whether it is in a nitrogen atmosphere or an air atmosphere, the residual weight of the boron phenolic resin modified with the Schiff base silane coupling agent of the present invention at 800°C gradually increases with the increase of the degree of silane self-condensation. Among them, the boron phenolic resin modified with the Schiff base silane coupling agent in Example 5 has the highest residual weight at 800°C in both nitrogen atmosphere and air atmosphere, and has the best heat resistance.

[0096] This invention synthesizes a silane coupling agent containing a hydroxyl-substituted aromatic Schiff base structure. Using traditional silanes and thermosetting resins as raw materials, the compatibility between organosilicon and thermosetting resins is significantly improved by adding a certain amount of coupling agent. The material of this invention exhibits excellent ablation resistance and has broad application prospects in the field of thermal protection materials. It is suitable for preparing structural components and protective materials for aircraft and related equipment that must withstand harsh environments such as high-temperature exhaust gases and aerodynamic heat flow.

Claims

1. A Schiff base silane coupling agent modified resin, characterized in that: It is a composite material prepared from the following components in parts by weight: Schiff base silane coupling agent 0.01-50 parts, thermosetting resin 100-500 parts, alkoxysilane 100-500 parts, organic acid 0-50 parts, and water 0-50 parts. The thermosetting resin is boron phenolic resin or modified boron phenolic resin; the Schiff base silane coupling agent is a product obtained by reacting aminoalkoxysilane and salicylaldehyde, wherein the aminoalkoxysilane is 3-aminopropyltriethoxysilane.

2. The Schiff base silane coupling agent modified resin according to claim 1, characterized in that: It is a composite material prepared from the following components in parts by weight: 10-20 parts Schiff base silane coupling agent, 140-160 parts thermosetting resin, 100-200 parts alkoxysilane, 0-10 parts organic acid, and 0-44.85 parts water. The alkoxysilane is methyltriethoxysilane, isobutyltriethoxysilane, γ-aminopropyltriethoxysilane, trimoxysilane, or dialkoxysilane; the organic acid is acetic acid, formic acid, propionic acid, butyric acid, citric acid, lactic acid, malic acid, or tartaric acid.

3. The Schiff base silane coupling agent modified resin according to claim 2, characterized in that: It is a composite material prepared from the following components in parts by weight: 14.41 parts Schiff base silane coupling agent, 150 parts thermosetting resin, 140 parts alkoxysilane, 0-9.74 parts organic acid, and 44.85 parts water.

4. The Schiff base silane coupling agent modified resin according to claim 3, characterized in that: It is a composite material prepared from the following components in parts by weight: 14.41 parts Schiff base silane coupling agent, 150 parts thermosetting resin, 140 parts alkoxysilane, 3.90-9.74 parts organic acid, and 44.85 parts water.

5. The Schiff base silane coupling agent modified resin according to claim 4, characterized in that: It is a composite material prepared from the following components in parts by weight: 14.41 parts Schiff base silane coupling agent, 150 parts thermosetting resin, 140 parts alkoxysilane, 3.90 parts organic acid, and 44.85 parts water.

6. The Schiff base silane coupling agent modified resin according to claim 1, characterized in that: The mass ratio of the aminoalkoxysilane to salicylaldehyde is 10:(3-5).

7. The Schiff base silane coupling agent modified resin according to claim 6, characterized in that: The mass ratio of the aminoalkoxysilane to salicylaldehyde is 10:4.

41.

8. The Schiff base silane coupling agent modified resin according to any one of claims 1-7, characterized in that: The Schiff base silane coupling agent is prepared by the following method: reacting an aminoalkoxysilane with salicylaldehyde in an organic solvent to obtain the Schiff base silane coupling agent; wherein the reaction temperature is 40-70℃ and the reaction time is 1-4 hours; the mass ratio of the aminoalkoxysilane to the organic solvent is 10:(50-200).

9. The Schiff base silane coupling agent modified resin according to claim 8, characterized in that: The organic solvent is ethanol, the reaction temperature is 60°C, and the reaction time is 2 hours; the mass ratio of the aminoalkoxysilane to the organic solvent is 10:

100.

10. A method for preparing the Schiff base silane coupling agent modified resin according to any one of claims 1-9, characterized in that: The method includes the following steps: (1) Thermosetting resin, alkoxysilane, Schiff base silane coupling agent, water and organic acid are added to an organic solvent to react. After the reaction is completed, a resin solution is obtained. The organic solvent is removed to obtain an intermediate. (2) Solidify the intermediate to obtain the final product.

11. The method according to claim 10, characterized in that: The organic solvents mentioned in steps (1) and (2) are alcohol solvents; the reaction temperature in step (1) is 80-100℃, the time is 2-8 hours, and the mass ratio of thermosetting resin to organic solvent is 150:(100-200).

12. The method according to claim 11, characterized in that: The organic solvent mentioned in steps (1) and (2) is ethanol; the reaction temperature in step (1) is 80°C and the reaction time is 4 hours.

13. The use of the Schiff base silane coupling agent modified resin according to any one of claims 1-9 in thermal protection materials, ablation-resistant materials, and fireproof materials.

14. The use according to claim 13, characterized in that: The thermal protection materials include thermal protection structural materials for aircraft and thermal protection materials for engines.

Images