Aromatic Schiff base silane modified ablation-resistant resin matrix material as well as preparation method and application thereof

Abstract

The invention provides an aromatic Schiff base silane modified ablation-resistant resin matrix material as well as a preparation method and application thereof, and belongs to the field of thermal protection materials. The silane coupling agent containing a hydroxyl substituted aromatic Schiff base structure is synthesized, traditional silane and thermosetting resin are used as raw materials, and a certain amount of coupling agent is added, so that the compatibility of organic silicon and the thermosetting resin is remarkably improved. The material disclosed by the invention has excellent ablation resistance, has a wide application prospect in the field of thermal protection materials, and is suitable for preparing structural components and protection materials of the structural components which are applied to aircrafts and related equipment and devices and need to be subjected to severe environments scoured by high-temperature fuel gas and pneumatic heat flow.

Description

Technical Field

[0001] The invention belongs to the field of heat protection materials, and in particular relates to an aromatic Schiff base silane-modified ablation-resistant resin matrix material and a preparation method and application thereof. Background Art

[0002] Thermal protection materials are an important guarantee for the safe service of aerospace vehicles in extreme environments. With the rapid development of flight technology, the thermal environment faced by the new generation of aircraft is becoming more and more severe.

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

[0004] Although traditional phenolic resin-based composite materials have good ablation properties and high material strength, their elongation at break and ablation carbon residue rate are relatively low, and the carbonization products are difficult to graphitize and have poor oxidation resistance. Problems such as carbon layer erosion may occur during flight, making it difficult for the material to meet the high heat protection, oxidation resistance and overload resistance requirements required for the future development of high Mach, high maneuverability and multi-airspace aircraft.

[0005] Polysiloxane is a polymer with excellent thermal stability and ablation properties. It has been widely used to modify phenolic resins to improve their flame retardancy or ablation properties in aerobic environments. Silicone that is blended or chemically bonded to the resin network can generate silica inorganic liquid film and silicon carbide ceramics in situ during the ablation carbonization process, thereby improving the ability of the carbon layer on the ablation surface of the material to resist thermal mechanical and chemical thermal oxidation losses. However, the solubility parameters between polysiloxane and organic polymers vary greatly, the compatibility between silicone and phenolic resin is poor, and macroscopic phase separation often occurs in hybrid resin systems.

[0006] To solve the problem of poor compatibility between silicone and phenolic resin, the most common method is to use silane coupling agent. However, the molecular chain structure of the general KH560 and KH550 silane coupling agents contains long-chain alkanes, which are easily degraded by heat. Moreover, as the amount of coupling agent added increases, the benzene ring content in the cross-linked network will gradually decrease, which will affect the carbonization performance of phenolic resin during the ablation process and lead to deterioration of ablation performance. Summary of the invention

[0007] In order to overcome the above problems existing in the prior art, the purpose of the present invention is to design a new multifunctional silane coupling agent based on the molecular structure of the hybrid resin to improve the poor compatibility between silicone and phenolic resin. Studies have found that hydroxyl-substituted Salen-based Schiff bases can react with phenolic resins under appropriate conditions. Therefore, the present invention designs and synthesizes a silane coupling agent containing a hydroxyl-substituted aromatic Schiff base structure, and the hydroxyl-substituted aromatic in the coupling agent provides a reaction site with the phenolic resin.

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

[0009] Further, the Schiff base silane coupling agent modified resin is a composite material prepared from the following components in parts by weight as raw materials: 10-20 parts of Schiff base silane coupling agent, 140-160 parts of thermosetting resin, 100-200 parts of alkoxysilane, 0-10 parts of organic acid, and 0-44.85 parts of water; preferably, it is a composite material prepared from the following components in parts by weight as raw materials: 14.41 parts of Schiff base silane coupling agent, 150 parts of thermosetting resin, 140 parts of alkoxysilane, 0-9.74 parts of organic acid, and 44.85 parts of 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, trialkoxysilane 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 as raw materials: 14.41 parts of Schiff base silane coupling agent, 150 parts of thermosetting resin, 140 parts of alkoxysilane, 3.90-9.74 parts of organic acid, and 44.85 parts of water.

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

[0013] Furthermore, the Schiff base silane coupling agent is a product obtained by the reaction of aminoalkoxysilane and salicylaldehyde or its derivatives;

[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 of 3-aminopropyltriethoxysilane, aminopropyltrimethoxysilane, bis(tert-butylamino)silane and 4-anilinotriethoxysilane, or a mixture of two or more thereof.

[0016] Furthermore, the Schiff base silane coupling agent is prepared by the following method: aminoalkoxysilane and salicylaldehyde or its derivatives are reacted in an organic solvent to obtain a Schiff base silane coupling agent; wherein the reaction temperature is 40-70°C, 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) adding a thermosetting resin, an alkoxysilane, a Schiff base silane coupling agent, water and an organic acid into an organic solvent for reaction, obtaining a resin solution after the reaction is completed, and removing the organic solvent to obtain an intermediate;

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

[0021] Furthermore, the organic solvent in step (1) and step (2) is an alcohol solvent; the reaction temperature in step (1) is 80-100° C., the reaction time is 2-8 hours, and the mass ratio of the thermosetting resin to the organic solvent is 150:(100-200);

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

[0023] The present invention also provides the use of the Schiff base silane coupling agent modified resin in heat protection materials, ablation resistant materials and fireproof materials.

[0024] Furthermore, the thermal protection material includes aircraft thermal protection structural material and engine thermal protection material.

[0025] The present invention synthesizes a silane coupling agent containing a hydroxyl-substituted aromatic Schiff base structure, and uses traditional silane and thermosetting resin as raw materials, and by adding a certain amount of coupling agent, the compatibility of organic silicon and thermosetting resin is significantly improved. The material of the present invention has 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 structural components that need to withstand the harsh environment of high-temperature combustion gas and aerodynamic heat flow scouring in aircraft and related equipment.

[0026] The ablation resistance and heat resistance of the Schiff base silane coupling agent modified boron phenolic resin prepared by the present invention are significantly improved, among which the ablation resistance of the Schiff base silane coupling agent modified boron phenolic resin obtained in Example 4 is the best, and the heat resistance of the Schiff base silane coupling agent modified boron phenolic resin obtained in Example 5 is the best. The Schiff base silane coupling agent modified boron phenolic resin of the present invention has broad application prospects in the field of thermal protection materials, and is suitable for preparing structural components and protective materials for structural components used in aircraft and related equipment and devices that need to withstand the harsh environment of high-temperature combustion gas and aerodynamic heat flow scouring.

[0027] Obviously, according to the above contents of the present invention, in accordance with common technical knowledge and customary means in the art, without departing from the above basic technical ideas of the present invention, other various forms of modification, replacement or change may be made.

[0028] The above contents of the present invention are further described in detail below through specific implementation methods in the form of embodiments. However, this should not be understood as the scope of the above subject matter of the present invention being limited to the following examples. All technologies realized based on the above contents of the present invention belong to the scope of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 Infrared spectra of Schiff base coupling agent modified boron phenolic resin (a) before curing, (b) during curing and (c) after curing; XPS (d) Si2p and (e) B1s spectra after curing of modified resin; (f) 29Si solid NMR spectrum of uncured resin; SEM morphology of brittle fracture surface and Si element mapping (g) SBPR 50-4 、(h)SBPR B50-4 .

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

[0031] Figure 3 (ah) Height cloud map and (ip) 3D morphology map of the sample surface after ablation for 30s: (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 line, (r) line ablation rate distribution and (s) width of the ablation retreat area.

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

[0033] Figure 5 (a, c) Thermogravimetric curves of each hybrid resin in nitrogen and air atmosphere after curing and (b, d) thermal residual weight at 800°C. DETAILED DESCRIPTION

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

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

[0036] Ethanol.

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

[0038] Table 1 Raw material formula of each sample

[0039]

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

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

[0042] Take 10g (0.045mol) 3-aminopropyltriethoxysilane, 4.41g (0.036mol) salicylaldehyde and 100g ethanol and add them into a flask. When the oil bath is heated to 60°C, keep it warm for 2h under inert atmosphere to obtain a bright yellow ethanol solution containing Schiff base silane coupling agent. The excess 3-aminopropyltriethoxysilane ensures that the salicylaldehyde in the system reacts completely, and the remaining 3-aminopropyltriethoxysilane in the system also plays a coupling role in the subsequent reaction.

[0043] Step 2. The Schiff base silane coupling agent of the present invention is modified with boron phenolic resin (SBPR50-0 )

[0044] 150 g of boron phenolic resin and 200 g of ethanol were added to a flask, stirred at room temperature until the boron phenolic resin was completely dissolved, and then 140 g of methyltriethoxysilane was added, stirred until uniformly dispersed, and finally the ethanol solution of Schiff base silane coupling agent prepared in step 1 of Example 1 was added. The oil bath was heated to 80° C. and reacted for 4 h under an inert atmosphere to obtain a 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 h to remove the solvent in the resin to obtain boron phenolic resin powder modified with Schiff base silane coupling agent.

[0046] The obtained modified boron phenolic resin powder is compression molded and cured, and the curing process is as follows: 110°C without pressure, maintained for 30 minutes; heating from 110°C to 140°C, with a heating rate of 5°C / min; keeping at 140°C for 30 minutes, and gradually pressurizing to 12-15MPa; heating from 140°C to 180°C, with a heating rate of 5°C / min, maintaining a pressure of 12-15MPa; keeping at 180°C for 2 hours, maintaining a pressure of 12-15MPa; heating from 180°C to 200°C, with a heating rate of 5°C / min, maintaining a pressure of 12-15MPa; keeping at 200°C for 1 hour, maintaining a pressure of 12-15MPa; finally, maintaining a pressure of 12-15MPa, and naturally cooling to room temperature to obtain a Schiff base silane coupling agent-modified boron phenolic resin ablation-resistant material.

[0047] Example 2-3, Schiff base silane coupling agent modified boron phenolic resin (Example 2SBPR 50-1 , Example 3SBPR 50-2 )

[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 formula was added to the flask, stirred at room temperature until the boron phenolic resin was completely dissolved, and then 140g of methyltriethoxysilane was added, stirred until uniformly dispersed, and finally the Schiff base silane coupling agent solution prepared in step 1 of Example 1 was added. The oil bath was heated to 80°C, and the deionized water mixed solution (the amount added is shown in Table 1) was added to the flask through a constant pressure dropping funnel under inert atmosphere. After the addition was completed, the reaction was continued at 80°C for 4h to obtain a 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 h to remove the solvent in the resin to obtain boron phenolic resin powder modified with Schiff base silane coupling agent.

[0050] The molding process is carried out and then cured. The curing process is the same as that in Example 1, and the ablation-resistant material SBPR containing a Schiff base silane coupling agent modified boron phenolic resin is obtained. 50-1 , SBPR 50-2 .

[0051] Example 4-5, Schiff base silane coupling agent modified boron phenolic resin (Example 4SBPR 50-3 , Example 5 SBPR 50-4 )

[0052] Take 150g of boron phenolic resin and 100g of ethanol and add them to a flask, stir at room temperature until the boron phenolic resin is completely dissolved, continue to add 140g of methyltriethoxysilane, stir until uniformly dispersed, and finally add the ethanol solution of Schiff base silane coupling agent prepared in step 1 of Example 1. Heat the oil bath to 80°C, and add acetic acid (addition amount corresponding to Table 1) and a mixed solution of deionized water (44.85g of deionized water) to the flask through a constant pressure dropping funnel under inert atmosphere. After the addition is completed, continue to react at 80°C for 4h to obtain a 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 h to remove the solvent in the resin to obtain boron phenolic resin powder modified with Schiff base silane coupling agent.

[0054] The molding process is carried out and then cured. The curing process is the same as that in Example 1, and the ablation-resistant material SBPR containing a Schiff base silane coupling agent modified boron phenolic resin is obtained. 50-3 , SBPR 50-4 .

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

[0056] Take 10g (0.045mol) 3-aminopropyltriethoxysilane, 4.41g (0.036mol) salicylaldehyde and 100g ethanol and add them into a flask. When the oil bath is heated to 60°C, keep it warm for 2h under inert atmosphere to obtain a bright yellow ethanol solution containing Schiff base silane coupling agent. The excess 3-aminopropyltriethoxysilane ensures that the salicylaldehyde in the system reacts completely, and the remaining 3-aminopropyltriethoxysilane in the system also plays a coupling role in the subsequent reaction.

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

[0058] Take 10g (0.045mol) 3-aminopropyltriethoxysilane, 3.42 (0.028mol) salicylaldehyde and 50g ethanol and add them into a flask. When the oil bath is heated to 70°C, keep it warm for 2h under inert atmosphere to obtain a bright yellow ethanol solution containing Schiff base silane coupling agent. The excess 3-aminopropyltriethoxysilane ensures that the salicylaldehyde in the system reacts completely, and the remaining 3-aminopropyltriethoxysilane in the system also plays a coupling role in the subsequent reaction.

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

[0060] Take 10g (0.045mol) 3-aminopropyltriethoxysilane, 4g (0.036mol) salicylaldehyde and 100g ethanol and add them into a flask. When the oil bath is heated to 65°C, keep it warm for 2h under inert atmosphere to obtain a bright yellow ethanol solution containing Schiff base silane coupling agent. The excess 3-aminopropyltriethoxysilane ensures that the salicylaldehyde in the system reacts completely, and the remaining 3-aminopropyltriethoxysilane in the system also plays a coupling role in the subsequent reaction.

[0061] The following is the preparation method of the control sample.

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

[0063] Take 150g of boron phenolic resin, 150g of methyltriethoxysilane and 300g of ethanol and add them to a flask, stir at room temperature until completely dissolved. Heat the oil bath to 80°C and react for 4 hours under inert atmosphere. After the reaction is completed, remove the solvent in the resin by rotary evaporation and vacuum oven to obtain silane-modified boron phenolic resin powder.

[0064] The molding process is the same as that in Example 1, and the silane-modified boron phenolic resin ablation-resistant material (SBPR) is obtained. B50-0 ).

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

[0066] Take 150g of boron phenolic resin, 150g of methyltriethoxysilane and 200g of ethanol and add them to a flask, stir at room temperature until completely dissolved. Heat the oil bath to 80°C, and add a mixed solution of acetic acid and deionized water (9.74g of acetic acid, 44.85g of deionized water) to the flask through a constant pressure dropping funnel under inert atmosphere. After the addition is complete, continue to react at 80°C for 4h. After the reaction is completed, remove the solvent in the resin by rotary evaporation and vacuum oven to obtain silane-modified boron phenolic resin powder.

[0067] The molding process is the same as that in Example 1, and the silane-modified boron phenolic resin ablation-resistant material (SBPR) is obtained. B50-4 ).

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

[0069] Boron phenolic resin powder BPR is used for compression molding and curing. The curing process is the same as that in Example 1, so as to obtain a boron phenolic resin ablation-resistant material (BPR').

[0070] The beneficial effects of the present invention are demonstrated by experimental examples below.

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

[0072] 1. Experimental Methods

[0073] Tested by infrared spectroscopy Figure 1 (ac) and 29Si solid state NMR Figure 1 (f) Characterize the structural changes of the modified resin before, during and after curing. Figure 1 (d, e) Characterization of the structural differences of the modified resin after curing. The organic silicon phase and Si element distribution were characterized by the brittle fracture scanning electron microscopy (SEM) morphology of the cured resin and its surface scanning (Mapping) mode. Figure 1 (g, h).

[0074] About SBPR 50-0 and SBPR 50-3 Small angle X-ray diffraction (SAXS) test was performed, and the experimental results are as follows Figure 2 As shown in a, each cured resin was tested by X-ray diffractometer (XRD), and the experimental results are shown in Figure 2 As shown in b.

[0075] 2. Experimental Results

[0076] Figure 1 a and Figure 1 In the infrared spectrum of the resin before and after curing, 1635 cm -1 The -CH=N peak at 960cm -1 and 910cm -1 The peaks of Si-O-Ph and Si-OB indicate that the organosilicon reacts with phenolic hydroxyl and boric hydroxyl groups to introduce siloxane into the phenolic resin in the form of covalent bonds.

[0077] Figure 1 b medium 960cm -1The Si-O-Ph bond strength at 1226 cm-1 is gradually weakened, indicating that it will be lost to a certain extent during the curing process. -1 The Ar-OH 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 Figure d, with the increase in the amount of deionized water / acetic acid added and the decrease in the amount of ethanol used, the relative content of Si-O-Si bonds in the Si element in the system gradually increased, from 32.3% in SBPR50-0 to 53.4% ​​in SBPR50-4, indicating that the degree of silane self-condensation in the system continued to increase.

[0079] Figure 1 e indicates that the B element in the cured resin participates in the resin curing by forming BOC, BOB and BO-Si, and the appearance of BO-Si bonds once again proves that silicone reacts with boron hydroxyl groups to connect siloxane to phenolic resin in the form of covalent bonds.

[0080] Figure 1 f shows that with the increase of deionized water / acetic acid addition and the decrease of ethanol usage, the number of ethoxy groups in the system continues to decrease, indicating that the degree of silane self-condensation increases.

[0081] contrast Figure 1 g and Figure 1 hIt can be seen that when the amount of deionized water / acetic acid added is the same as that of ethanol, the addition of Schiff base coupling agent causes the silicone to be phased by micron size in the phenolic resin ( Figure 1 h) The system was transformed into a homogeneous system and no obvious phase separation was observed.

[0082] The experimental results show that the present invention can change the degree of silane self-condensation in the system by adjusting the amount of deionized water, acetic acid and ethanol in the formula. The present invention continuously improves the degree of silane self-condensation in the system by increasing the amount of deionized water, acetic acid and ethanol in the formula. At the same time, the present invention adds a Schiff base coupling agent, and when the degree of silane self-condensation in the system is not much different, the organosilicon in the system is transformed from a micron-scale phase to a homogeneous system, which significantly improves the compatibility of organosilicon and boron phenolic resin.

[0083] Figure 2 aAs you can see, SBPR 50-0 The SAXS curve of the sample has no scattering peak, indicating that there is no microstructure; SBPR 50-3 The SAXS curve of the sample shows a weak scattering shoulder. Calculated by the Bragg formula (L=2π / q), the average distance between adjacent organic silicon phases is 14.3 nm. Figure 2b It can be seen that there is a passive amorphous diffraction peak at around 10.7°, corresponding to the organic silicon phase; for SBPR without adding Schiff base coupling agent B50-4 The peak intensity of the sample increased significantly and the peak shape became narrower, indicating that the size of the organosilicon phase was larger. The experimental results once again proved that the addition of the Schiff base coupling of the present invention can significantly improve the compatibility of organosilicon with boron phenolic resin.

[0084] Experimental Example 2: Ablation Performance Test of the Modified Boron Phenolic Resin of the Present Invention

[0085] 1. Experimental Methods

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

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

[0088]

[0089]

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

[0091] Experimental Example 3: Heat resistance test of the modified boron phenolic resin of the present invention

[0092] The thermal gravimetric curves of the cured samples in nitrogen (N2) and air (Air) atmospheres were tested by a thermogravimetric analyzer (TG) to obtain the thermal residual weight at 800°C. Figure 5 And as shown in Table 3.

[0093] Table 3 800℃ heat residual weight of each cured resin (%)

[0094]

[0095] It can be seen that, whether in nitrogen or air atmosphere, the 800°C thermal residual weight of the boron phenolic resin modified by the Schiff base silane coupling agent of the present invention gradually increases with the increase of the degree of silane self-condensation, among which the boron phenolic resin modified by the Schiff base silane coupling agent in Example 5 has the highest 800°C thermal residual weight in nitrogen atmosphere and in air atmosphere, and has the best heat resistance.

[0096] The present invention synthesizes a silane coupling agent containing a hydroxyl-substituted aromatic Schiff base structure, and uses traditional silane and thermosetting resin as raw materials, and by adding a certain amount of coupling agent, the compatibility of organic silicon and thermosetting resin is significantly improved. The material of the present invention has 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 structural components that need to withstand the harsh environment of high-temperature combustion gas and aerodynamic heat flow scouring in aircraft and related equipment.

Claims

1. A Schiff base silane coupling agent modified resin, characterized in that: The composite material is prepared from the following components in parts by weight as raw materials: 0.01-50 parts of Schiff base silane coupling agent, 100-500 parts of thermosetting resin, 100-500 parts of alkoxy silane, 0-50 parts of organic acid and 0-50 parts of water.

2. The Schiff base silane coupling agent modified resin according to claim 1, characterized in that: The composite material is prepared from the following components in parts by weight as raw materials: 10-20 parts of Schiff base silane coupling agent, 140-160 parts of thermosetting resin, 100-200 parts of alkoxysilane, 0-10 parts of organic acid, and 0-44.85 parts of water; preferably, the composite material is prepared from the following components in parts by weight as raw materials: 14.41 parts of Schiff base silane coupling agent, 150 parts of thermosetting resin, 140 parts of alkoxysilane, 0-9.74 parts of organic acid, and 44.85 parts of water; 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, trialkoxysilane 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: The composite material is prepared from the following components in parts by weight as raw materials: 14.41 parts of Schiff base silane coupling agent, 150 parts of thermosetting resin, 140 parts of alkoxy silane, 3.90-9.74 parts of organic acid and 44.85 parts of water.

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

5. The Schiff base silane coupling agent modified resin according to any one of claims 1 to 4, characterized in that: The Schiff base silane coupling agent is a product obtained by the reaction of aminoalkoxysilane and salicylaldehyde or its derivatives; The mass ratio of the aminoalkoxysilane to salicylaldehyde or its derivative is 10:(3-5), preferably 10:4.41; The aminoalkoxysilane is any one of 3-aminopropyltriethoxysilane, aminopropyltrimethoxysilane, bis(tert-butylamino)silane and 4-anilinotriethoxysilane, or a mixture of two or more thereof.

6. The Schiff base silane coupling agent modified resin according to any one of claims 1 to 5, characterized in that: The Schiff base silane coupling agent is prepared by the following method: aminoalkoxysilane and salicylaldehyde or its derivatives are reacted in an organic solvent to obtain a Schiff base silane coupling agent; wherein the reaction temperature is 40-70° C., and the reaction time is 1-4 hours; and the mass ratio of the aminoalkoxysilane to the organic solvent is 10:(50-200); 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.

7. A method for preparing the Schiff base silane coupling agent modified resin according to any one of claims 1 to 6, characterized in that: The method comprises the following steps: (1) adding a thermosetting resin, an alkoxysilane, a Schiff base silane coupling agent, water and an organic acid into an organic solvent for reaction, obtaining a resin solution after the reaction is completed, and removing the organic solvent to obtain an intermediate; (2) Solidify the intermediate to obtain the product.

8. The method according to claim 7, characterized in that: The organic solvent in step (1) and step (2) is an alcohol solvent; the reaction temperature in step (1) is 80-100° C., the reaction time is 2-8 hours, and the mass ratio of the thermosetting resin to the organic solvent is 150:(100-200); Preferably, the organic solvent in step (1) and step (2) is ethanol; the reaction temperature in step (1) is 80° C. and the reaction time is 4 hours.

9. Use of the Schiff base silane coupling agent modified resin according to any one of claims 1 to 6 in thermal protection materials, ablation resistant materials and fireproof materials.

10. The use according to claim 9, characterized in that: The thermal protection materials include aircraft thermal protection structural materials and engine thermal protection materials.

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