Novel long-time oxidation-resistant ablation-resistant thermal protection matrix resin as well as preparation method and application of novel long-time oxidation-resistant ablation-resistant thermal protection matrix resin

Abstract

The invention provides novel long-time antioxidant ablation-resistant thermal protection matrix resin as well as a preparation method and application thereof, and belongs to the field of advanced high polymer materials. Carborane resin reacts with phenolic resin and silica sol to prepare carborane-silica sol phenolic resin, and the carborane-silica sol phenolic resin has higher initial thermal decomposition temperature and high thermal residual weight compared with common phenolic resin; in addition, the material has the characteristic of continuously releasing pyrolysis gas in a wide temperature range, the ablation resistance of the material is remarkably improved compared with that of traditional phenolic resin, and the material has important application prospects in the thermal protection field of high-speed aircrafts such as long endurance, ultra-long distance and near space.

Description

Technical Field

[0001] This invention belongs to the field of advanced polymer materials, specifically relating to a novel long-lasting antioxidant and ablation-resistant thermal protective matrix resin, its preparation method, and its applications. Background Technology

[0002] Long-range high-speed aircraft face severe aerodynamic heating during near-space flight, making thermal protection technology crucial for their safe operation. Ablation-type thermal protection materials, characterized by efficient energy dissipation, self-renewing surfaces, lightweight nature, and high-temperature resistance, have become the mainstream thermal protection materials for extreme thermal environments. The small-molecule gases generated during pyrolysis under aerodynamic conditions form an airflow boundary layer on the ablation surface, inhibiting heat transfer into the aircraft and significantly reducing aerodynamic heating. Phenolic resins are widely used as ablation thermal protection materials due to their excellent char-forming and ablation properties. However, traditional phenolic resin thermal protection materials undergo rapid and intense pyrolysis under oxidizing conditions, and the short duration of the airflow boundary layer makes them unsuitable for the long-term thermal protection requirements of long-range high-speed aircraft in high-temperature oxidizing environments. Therefore, there is an urgent need to improve the oxidation resistance of phenolic resins.

[0003] Compared to traditional phenolic resins, ceramizable phenolic resin composites exhibit superior ablation resistance and oxidation resistance. Many phenolic resin composites containing boron and silicon ceramic fillers have been widely used in ramjet engine combustion chambers and rocket nozzle throats. At high temperatures, these fillers react with the pyrolytic carbon of the resin to form ceramics, which then melt in a high-temperature flow environment to fill the pores created by pyrolysis, thereby inhibiting the erosion of the aircraft interior by hot oxygen flow. However, generating a uniform and effective barrier layer on the material surface often requires a large amount of ceramic filler, and the introduction of a large amount of inorganic filler may negatively impact processing and mechanical properties. To address these issues, the introduction of heteroatoms such as boron and silicon into the resin to construct organic-inorganic hybrid polymers, endowing the polymers with in-situ ceramization properties, has received increasing attention.

[0004] Boron-modified phenolic resins exhibit excellent antioxidant properties at lower temperatures. For example, the literature (DOI:10.1016 / j.polymdegradstab.2025.111335) reports that constructing a carborane hybrid crosslinking network can significantly improve the thermal oxidation stability and ablation resistance of phenolic resins. However, the prepared hybrid resin (CBPR) still suffers from a high mass ablation rate (MAR), and its performance at 800℃ (R0) is also problematic. 800℃The residual weight of boron-based ceramics still needs improvement. This problem stems from the fact that boric acid (H3BO3) and metaboric acid (HBO2), generated by the pyrolysis of boron-containing structures at high temperatures (>800℃), are easily vaporized and volatilized, weakening the protective effect of the boron-based ceramic melt layer. In contrast, silicon-modified phenolic resins have a greater advantage at high temperatures. The pyrolysis of siloxanes can form a SiO2-rich molten protective layer, and at temperatures above 1400℃, it can generate a SiC ceramic phase through a carbothermic reduction reaction, further strengthening the high-temperature barrier. However, the unmodified organosilicon segments have poor compatibility with the phenolic matrix, and are prone to rearrangement reactions at 300–400℃, releasing low-molecular-weight gaseous cyclosilanes, leading to a decrease in ceramic conversion rate and ultimately affecting the actual ablation protection performance of silicon-modified phenolic resins.

[0005] To address the problem that existing hybrid modified phenolic resins decompose violently within a specific temperature range and fail to maintain their high-temperature resistance and antioxidant protection over a wide temperature range, resulting in insignificant improvement in ablation thermal protection performance, it is of great practical significance and an urgent research need to develop a novel phenolic resin that can meet the long-term thermal protection requirements of aerobic environments in aerospace vehicles. Summary of the Invention

[0006] To address the issues of significant loss of ceramization-promoting elements and low ceramic conversion rates in existing boron- and silicon-modified phenolic resins within specific temperature ranges, resulting in poor ablation performance under aerobic high-temperature environments, this invention proposes a boron-silicon hybrid phenolic resin preparation strategy using a condensation-addition double crosslinking network. This invention utilizes the in-situ chemical crosslinking characteristics of boron and silanes during pyrolysis to endow the resin with pyrolysis-controlled release capabilities, thereby improving its thermo-oxidative stability and ablation performance over a wide temperature range. This provides a new solution for long-term, efficient thermal protection of aerospace vehicles in aerobic environments and has significant application value.

[0007] This invention provides a carborane-modified thermosetting resin, which is prepared from carborane alkyl materials, thermosetting resin with unsaturated bonds, and silica sol as raw materials; wherein the mass ratio of carborane alkyl materials, thermosetting resin with unsaturated bonds, and silica sol is 0.5-2:2:0.5-2.

[0008] Furthermore, the mass ratio of the carborane alkyl material, the thermosetting resin with unsaturated bonds, and the silica sol is 1:2:1.

[0009] Furthermore, the thermosetting resin with unsaturated bonds is a thermosetting resin with allyl groups, and the preparation method of the thermosetting resin with allyl groups includes the following steps: reacting the thermosetting resin, catalyst, and allylating agent, and drying to obtain the product.

[0010] The method for preparing the silica sol includes the following steps: mixing tetraethyl orthosilicate and siloxane with a solvent to obtain mixture A; mixing water, a catalyst, and a solvent to obtain mixture B; and reacting mixture A and mixture B to obtain the final product.

[0011] Furthermore, the mass ratio of the thermosetting resin, catalyst, and allylating agent is 140–150: 25–40: 15–80.

[0012] Furthermore, the catalyst is selected from organic or inorganic bases such as potassium hydroxide, sodium hydroxide, barium hydroxide, sodium carbonate, and triethylamine;

[0013] The allylating agent is selected from allyl bromide or allyl chloride.

[0014] Furthermore, the solvent for the reaction is an organic solvent, preferably ethanol;

[0015] The reaction is carried out at a temperature of 60–70°C for 5–10 hours.

[0016] Furthermore, the thermosetting resin is selected from phenolic resin, epoxy resin, unsaturated polyester resin, melamine-formaldehyde resin, furan resin or polybutadiene resin, preferably phenolic resin.

[0017] Furthermore, the siloxane is selected from one or a mixture of two of tetraethyl orthosilicate, methyltriethoxysilane, and vinyltriethoxysilane;

[0018] The catalyst is ammonia water;

[0019] The solvent is an organic solvent, preferably isopropanol.

[0020] The reaction is carried out at a temperature of 30–50°C for 5–15 hours.

[0021] Furthermore, the preparation method of the carborane alkyl material includes the following steps: reacting carborane phenol, phenolic compound with unsaturated bond, aldehyde reagent and catalyst in a solvent, and drying to obtain carborane alkyl material; the mass ratio of carborane phenol, phenolic compound with unsaturated bond and aldehyde reagent is 1:0.5~5:0.5~5.

[0022] Furthermore, the mass ratio of the carboranephenol, the phenolic compound with unsaturated bonds, and the aldehyde reagent is 1:0.5-3:1.5-3.

[0023] Furthermore, the aldehyde reagent is selected from one or more mixtures of aliphatic aldehydes and aromatic aldehydes;

[0024] The catalyst is one or more of the following: inorganic base, gaseous alkaline substance, aliphatic organic base, and aromatic organic base;

[0025] The phenolic compounds with unsaturated bonds are phenolic compounds with allyl groups.

[0026] Furthermore, the aliphatic aldehydes are selected from one or more mixtures of formaldehyde, acetaldehyde, propionaldehyde, isobutyraldehyde, pentanal, or paraformaldehyde;

[0027] The aromatic aldehydes are selected from one or more mixtures of benzaldehyde, terephthalaldehyde, or furfural.

[0028] The catalyst is selected from one or more mixtures of ammonia, sodium hydroxide, potassium hydroxide, barium hydroxide, magnesium hydroxide, calcium hydroxide, sodium carbonate, ethylenediamine, triethylamine, hexamethylenetetramine, ethanolamine, triethanolamine, aniline, and o-phenylenediamine.

[0029] Furthermore, the aldehyde reagent is formaldehyde;

[0030] The catalyst is ammonia.

[0031] Furthermore, the solvent for the reaction is an organic solvent or a mixture of multiple organic solvents that has good solubility for the above-mentioned phenols, aldehydes, and phenolic resins.

[0032] Furthermore, the solvent for the reaction is one or more of the following: low molecular weight alcohols (such as methanol, ethanol, isopropanol, n-propanol, ethylene glycol, n-butanol, tert-butanol, etc.); ethers (such as diethyl ether, tetrahydrofuran, dioxane, etc.); ketones (such as acetone, methyl ethyl ketone, cyclohexanone, etc.); esters (such as ethyl acetate, butyl acetate, etc.); and aromatic hydrocarbons (such as benzene, toluene, xylene, etc.), preferably isopropanol or n-propanol.

[0033] Furthermore, the method for preparing the carboranephenol includes the following steps:

[0034] Carboranephenol precursor reacts with a demethylating agent to yield carboranephenol; wherein the molar ratio of carboranephenol precursor to demethylating agent is 1:3 to 12;

[0035]

[0036] R1 is selected from hydrogen and C. 1～5 Alkyl, C 2～5 alkenyl, C 1～5 Alkoxy, unsubstituted or R a Substituted 5- to 6-membered aryl groups;

[0037] R2 is selected from hydroxyl protecting groups, silyl protecting groups, ether protecting groups, silyl ether protecting groups, or ester protecting groups; R2 is selected from -LR. b -COR d Not replaced or Rc The following groups are substituted: C 1～5 Alkyl, silicon-based;

[0038] R3 is selected from hydrogen, C 1～5 Alkyl, C 2～5 alkenyl, C 1～5 Alkoxy, unsubstituted or R a Substituted 5- to 6-membered aryl groups;

[0039] R a Selected independently from C 1～5 Alkoxy;

[0040] R c Independently selected from 5-6 aryl, C 1～5 Alkyl, C 1～5 Alkoxy, -LR b ;

[0041] L is selected from C 1～5 Alkylene, C 1～5 Alkoxy;

[0042] R b Independently selected from unsubstituted or R a Substituted 5- to 6-membered aryl groups;

[0043] R d Selected independently from C 1～5 Alkyl, 5-6 aryl, halogen-substituted C 1～5 alkyl.

[0044] Furthermore, the method for preparing the carboranephenol includes the following steps:

[0045]

[0046] Further, the demethylating agent is boron trichloride, boron tribromide, hydrobromic acid, hydroiodic acid, boron trifluoride diethyl ether, aluminum trichloride, ferric chloride, boron trifluoride, pyridine hydrochloride, or p-toluenesulfonic acid, preferably boron tribromide.

[0047] Furthermore, the preparation method of the carboranephenol precursor includes the following steps:

[0048]

[0049] Furthermore, the preparation method of the carboranephenol precursor includes the following steps:

[0050]

[0051] Furthermore, the preparation method of the decaboron-dodecyl diacetonitrile complex includes the following steps:

[0052]

[0053] The present invention also provides a method for preparing the above-mentioned carborane-modified thermosetting resin, the method comprising the following steps: heating and mixing carborane alkyl materials, thermosetting resin with unsaturated bonds and silica sol, drying, and curing to obtain the resin.

[0054] Further, the heating and mixing conditions are: stirring at 60-100℃ for 1-5 hours; the drying conditions are: drying at 60-100℃ for 1-5 hours; and the curing conditions are: heating at a gradient of 120-220℃ for 0.2-2 hours under a pressure of 5-10MPa.

[0055] Further, the heating and mixing conditions are: reacting at 80°C for 2-3 hours; the drying conditions are: drying at 90°C for 4-5 hours; the curing conditions are: curing at 120°C for 30 minutes, 160°C for 1 hour, 180°C for 2 hours, 200°C for 1 hour, and 220°C for 1 hour under a pressure of 5-10 MPa.

[0056] This invention also provides the use of the above-mentioned carborane-modified phenolic resin in the preparation of thermal protective coatings for long-endurance, ultra-long-range, near-space high-speed aircraft, aerospace reciprocating aircraft, high-temperature resistant thermal protective composite materials, and high-temperature resistant sealant adhesives.

[0057] The present invention has achieved the following beneficial effects:

[0058] (1) This invention designs the molecular structure and further introduces the inorganic structure into the polymer crosslinking network through copolymerization and co-curing to obtain carborane-silica sol phenolic resin. Compared with the addition of nano-scale fillers and the blending modification of silicone oil and silicone rubber, carborane-silica sol phenolic resin has good compatibility and does not require surface modification (coupling agent treatment, plasma treatment, etc.) or complex dispersion and mixing processes (ultrasound, internal mixing, high-speed stirring, etc.).

[0059] (2) Traditional polymer materials have a narrow pyrolysis temperature range and degrade rapidly in a short period of time. This means that a certain polymer can only provide sacrificial protection for a short time within a specific temperature range, which greatly increases the difficulty of designing sacrificial thermal protection structures. However, the carborane-silica sol phenolic resin of this invention has a higher initial thermal decomposition temperature, higher residual weight, wider pyrolysis temperature range and lower gas release than ordinary phenolic resins. It can continuously release pyrolysis gases to provide sacrificial protection over a wider temperature range.

[0060] (3) Traditional phenolic resins exhibit excellent thermal stability in high-temperature ranges due to their self-ceramicization properties. However, the siloxanes themselves are prone to cyclization degradation, leading to severe weight loss in the 300-400℃ temperature range. A large amount of siloxanes is released in gaseous form before being converted into ceramic compounds, resulting in a low ceramic conversion rate and poor protective effect. This invention introduces carboranes into phenolic resins that gradually generate boron hydroxyl groups during pyrolysis. The condensation reaction between boron and silanol hydroxyl groups inhibits the cyclization degradation of siloxanes, improving the degree of ceramicization and enhancing the resin's thermal stability in air.

[0061] (4) The CBPR prepared in the literature (DOI:10.1016 / j.polymdegradstab.2025.111335) was tested for its mass ablation rate and at 800℃ using an oxyacetylene ablation apparatus (ZR-323A, Xi'an Zhirui Company). 800℃ To compare the differences between CBPR and the carborane-silica sol phenolic resin of this invention, the differences were simultaneously tested on an oxyacetylene ablation apparatus (Beijing Qinhe Technology Co., Ltd.). It was found that under the same test conditions and equipment, the carborane-silica sol phenolic resin (0.75APR) of this invention... B1-Si1 The mass ablation rate was reduced to 0.054 g / s, a 12.9% reduction compared to CBPR, achieving unexpected technical results; the carborane-silica sol phenolic resin (0.75APR) of this invention... B3-Si1 ) of R 800℃ The yield was increased to 71.26%, a 55% improvement over CBPR, achieving unexpected technical results. This invention, a carborane-silica sol phenolic resin, has significant application prospects in the thermal protection of high-speed aircraft such as those with long endurance, ultra-long range, and near-space applications.

[0062] (5) Compared with other advanced phenolic resin composites reported in the prior art (Synthesis of phenolic resins with cyclotriphosphazene for enhancement of ablation and char yields; Effect of Mesophase Pitch Incorporation on the Ablation Behavior and Mechanism of Phenolic Composites; Structure and improved thermal stability of phenolic resin containing silicon and boron elements; Ceramicization mechanism and thermal insulation / ablative properties of hollow microspheres / boron phenolic composites; Laser Shielding and Thermal Ablation Characteristics of Resorcinol Formaldehyde / Boron Nitride Composites for Thermal Protection Systems), the mass ablation rate of the carborane-silica sol phenolic resin of the present invention is further reduced and the ablation resistance is further improved.

[0063] 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.

[0064] 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 embodiments. All technologies implemented based on the above-described content of the present invention fall within the scope of the present invention. Attached Figure Description

[0065] Figure 1 This is a schematic diagram for preparing hybrid phenolic resin.

[0066] Figure 2Characterization data for the decaboron-dodecyl diacetonitrile complex (CB): (a) 1H NMR spectrum; (b) 1C NMR spectrum; (c) 1B NMR spectrum; (d) Infrared spectra of decylborane, acetonitrile, and the decaboron-dodecyl diacetonitrile complex.

[0067] Figure 3 (a) 1H NMR spectrum of carboranephenol (CBP); (b) 1C NMR spectrum.

[0068] Figure 4 The images show the 1H NMR spectra of (a) allyl phenolic resin (APR) and (b) allyl carborane phenolic resin (CBAPR), the infrared spectra of carborane-silica sol phenolic resin, the XPS energy dispersive spectroscopy, and (e) scanning electron microscopy images.

[0069] Figure 5 Thermogravimetric analysis (TGA) and differential thermogravimetric analysis (DTG) curves of carborane-silica sol phenolic resin in air atmosphere, and at 4MW / m 2 (c) Mass ablation rate (MAR) and (d) Linear ablation rate (LAR) after 30 s of oxyacetylene flame ablation.

[0070] Figure 6 Infrared spectra of pyrolysis gases from ordinary phenolic resin and carborane-silica sol phenolic resin in air atmosphere (ab); (cf) Schematic diagram showing the changes in the release of carbon dioxide, carbon monoxide, alkanes, and hydroxyl compounds with temperature. Detailed Implementation

[0071] The raw materials and equipment used in this invention are all known products, obtained by purchasing commercially available products.

[0072] In this invention, "room temperature" means 25±10℃.

[0073] Example 1: Preparation of allyl carboroline phenolic resin

[0074] 1. Preparation of decaboron-dodecyl diacetonitrile complex (CB)

[0075] Decaborane was dissolved in anhydrous acetonitrile and heated under an anhydrous and oxygen-free environment for a period of time. After the reaction was completed, the mixture was cooled for a period of time to obtain a white powdery product with the molecular formula B. 10 H 12 (CH3CN)2, abbreviated as CB. Structural characterization data: Figure 2 .

[0076] 2. Preparation of 4-methoxycarboborane (CBE)

[0077] In an anhydrous and oxygen-free environment, 4-ethynyl anisole and B... 10 H 12The addition reaction of (CH3CN)2 yields 4-methoxycarboborane, abbreviated as CBE.

[0078] 3. Preparation of carboranephenol (CBP)

[0079] The methyl group in CBE was removed using BBr3 to yield carborane phenol (CBP). Structural characterization data: Figure 3 .

[0080] 4. Preparation of allyl carboborane phenolic resin (CBAPR)

[0081] Carborane phenol (CBP, 20 g), 2-allylphenol (AP, 20 g), and 38 wt% formaldehyde aqueous solution (37 g) were dissolved in isopropanol (500 mL), and concentrated ammonia (8 mL) was added for catalysis. The mixture was then heated to 80 °C and reacted at this temperature for 8 h. After the reaction was complete, the solvent was removed using a rotary evaporator, yielding a reddish-brown viscous allyl carborane phenol resin (CBAPR). Structural characterization data: Figure 4 b.

[0082] Example 2: Preparation of carborane-silica sol phenolic resin

[0083] 1. Preparation of allylphenolic resin (APR)

[0084] A 50 wt% solution of phenolic resin (70 wt%, 143 g) was prepared by dissolving it in ethanol (30 g), and KOH (26 g, 26 g, 37 g) was added. The solution was then heated to 80 °C until the KOH was completely dissolved, and then cooled to 65 °C. Allyl bromide (17 g, 53 g, 79 g) was added dropwise over 1 hour. The solution was then heated back to 65 °C and maintained for 6 hours. After the reaction was complete, the solution was washed with H₂O and extracted with ethyl acetate to remove salts and residues.

[0085] KOH. The solvent was removed using a rotary evaporator, and the product was further dried under vacuum at 80°C for 5 hours to obtain reddish-brown oily allylphenolic resins with different degrees of substitution, named 0.25 APR, 0.50 APR, and 0.75 APR according to their degree of substitution. Structural characterization data: Figure 4 a.

[0086] 2. Preparation of silica sol (Si-sol)

[0087] Adopting improved Silica sol was prepared by a specific method. Tetraethyl orthosilicate (TEOS, 0.3 mol, 62.5 g), methyltriethoxysilane (MTOS, 0.15 mol, 26.74 g), and vinyltriethoxysilane (VTOS, 0.05 mol, 9.52 g) were added to 160 mL of isopropanol to obtain mixture A. Deionized water (4 mol, 72 g), 0.25 g ammonia, and 160 mL of isopropanol were mixed to obtain mixture B. Mixture A was then rapidly added to mixture B, and the mixture was vigorously stirred at room temperature. The mixture was further reacted at 40 °C for 10 h to finally obtain a homogeneous silica sol (Si-sol).

[0088] 3. Preparation and curing of carborane-silica sol phenolic resin

[0089] like Figure 1 As shown, 0.25APR and CBAPR were dissolved in tetrahydrofuran (THF) to obtain a 50wt% transparent solution. According to the material formulation in Table 1, Si-sol was added to the above solution (the mass ratio of 0.25APR, CBAPR, and Si-sol was 2:1:1), and reacted at 80°C for 2-3 hours. The solvent was removed by rotary evaporation, and the resin was further dried in a vacuum oven at 90°C for 4-5 hours to obtain a block resin. The block resin was pulverized into powder using a pulverizer. The resin powder was filled into a steel mold and cured by hot pressing at a gradient temperature of 120°C for 30 minutes, 160°C for 1 hour, 180°C for 2 hours, 200°C for 1 hour, and 220°C for 1 hour, with a pressure of 5-10 MPa. This yielded a carborane-silica sol phenolic resin (denoted as 0.25APR). B1-Si1 ).

[0090] Reference 0.25 APR B1-Si1 The preparation method, according to the material formulation in Table 1, under the same experimental conditions, yielded carborane-silica sol phenolic resins with different degrees of substitution (denoted as 0.50 APR). B1-Si1 0.75 APR B1-Si1 ).

[0091] Example 3: Preparation of carborane-silica sol phenolic resins with different proportions

[0092] Reference 0.25 APR B1-Si1 The preparation method differs only in that, according to the mass ratio of 0.75APR, CBAPR, and Si-sol of 4:1:3 (according to the material formulation in Table 1), and under the same experimental conditions, carborane-silica sol phenolic resin (denoted as 0.75APR) was prepared. B3-Si1 ).

[0093] Table 1. Composition of different groups of phenolic resins

[0094]

[0095]

[0096] The following is the method for preparing the control sample.

[0097] Comparative Example 1: Preparation of pure PR phenolic resin

[0098] Reference 0.25 APR B1-Si1 The preparation method is as follows: according to the material formulation in Table 1, under the same experimental conditions, pure PR phenolic resin (denoted as PR) was prepared using phenolic resin.

[0099] Comparative Example 2: Preparation of phenolic resin containing only silica sol

[0100] Reference 0.25 APR B1-Si1 The preparation method, following the material formulation in Table 1, under the same experimental conditions, utilizes phenolic resin and Si-sol to prepare a phenolic resin containing only silica sol (denoted as SiPR). Comparative Example 3: Preparation of a phenolic resin containing only carborane.

[0101] Hydroxymethylated carborane segments (CBPF) were prepared according to the method described in the literature (DOI:10.1016 / j.polymdegradstab.2025.111335).

[0102] Reference 0.25 APR B1-Si1 The preparation method is as follows: according to the material formulation in Table 1, under the same experimental conditions, phenolic resin containing only carborane (denoted as CBPR) is prepared using phenolic resin and CBPF.

[0103] The following experimental examples demonstrate the beneficial effects of the present invention.

[0104] Experiment Example 1: Testing the performance of carborane-silica sol phenolic resin

[0105] 1. Experimental Methods

[0106] (1) Thermogravimetric curves were obtained using TG209F1 (Gertebau GmbH, Germany). All samples (5 mg) were heated from 50 °C to 800 °C at a heating rate of 10 °C / min.

[0107] (2) Using an oxyacetylene ablation device (Beijing Qinhe Technology Co., Ltd.) at 4MW / m 2 Each sample was subjected to an ablation performance test for 30 seconds under a hot flow. The acetylene gas pressure was 0.095 MPa and the flow rate was 18.6 L / min. The oxygen gas pressure was 0.4 MPa and the flow rate was 25.2 L / min. The distance between the flame nozzle (inner diameter: 2.0 mm) and the sample surface was 10 mm.

[0108] 2. Experimental Results

[0109] Table 2. TGA, DTG, and 4MW / m³ values ​​of different phenolic resins under air atmospheres. 2 Mass ablation rate and linear ablation rate after 30 s of oxyacetylene flame ablation

[0110]

[0111] Figure 5 , Figure 6 The results in Table 2 show that the silica sol-carborane modified phenolic resin of the present invention has a higher initial thermal decomposition temperature, higher thermal residual weight, wider pyrolysis temperature range and lower gas release than ordinary phenolic resin. It can continuously release pyrolysis gases over a wider temperature range to play a sacrificial protection role.

[0112] Compared with PR, the addition of Si-sol, APR, and CBAPR improves the thermal stability of the hybrid resin, achieving a stability of 4MW / m 2 The mass ablation rate under oxyacetylene flame ablation was significantly reduced, indicating that the high-temperature ablation resistance and thermal protection performance were significantly improved.

[0113] Compared to CBPR, the hybrid resin 0.25APR of this invention, after incorporating Si-sol, APR, and CBAPR, exhibits better hybrid resin quality. B1-Si1 0.50 APR B1-Si1 0.75 APR B1-Si1 0.75 APR B3-Si1 At 4MW / m 2 The mass ablation rate under oxyacetylene flame ablation further decreased. Especially at 0.75 APR. B1-Si1 The mass ablation rate was reduced to 0.054 g / s, a 12.9% reduction compared to CBPR, achieving unexpected technical results.

[0114] Compared to CBPR, the hybrid resin 0.75APR of this invention, after incorporating Si-sol, APR, and CBAPR, has a higher viscosity. B1-Si1 0.75 APR B3-Si1 The thermal weight loss in air was also increased, and the thermal stability was improved. Specifically, 0.75 APR... B3-Si1 R 800℃ It was increased to 71.26%, a 55% improvement over CBPR, achieving unexpected technical results.

[0115] In summary, this invention provides a novel long-lasting, antioxidant, and ablation-resistant thermal protective matrix resin, its preparation method, and its applications. This invention utilizes the reaction of carborane resin with phenolic resin and silica sol to prepare a carborane-silica sol phenolic resin. This carborane-silica sol phenolic resin exhibits a higher initial thermal decomposition temperature and higher residual weight than ordinary phenolic resins. Furthermore, this material possesses the characteristic of continuously releasing pyrolysis gases over a wide temperature range, and its ablation resistance is significantly improved compared to traditional phenolic resins, showing significant application prospects in the thermal protection of high-speed aircraft such as long-endurance, ultra-long-range, and near-space vehicles.

Claims

1. A novel long-lasting antioxidant and ablation-resistant thermal protective matrix resin, characterized in that, It is prepared from carborane alkyl materials, thermosetting resins with unsaturated bonds and silica sol as raw materials; wherein the mass ratio of carborane alkyl materials, thermosetting resins with unsaturated bonds and silica sol is 0.5~2:2:0.5~2.

2. The novel long-lasting antioxidant and ablation-resistant thermal protective matrix resin according to claim 1, characterized in that, The thermosetting resin with unsaturated bonds is a thermosetting resin with allyl groups. The preparation method of the thermosetting resin with allyl groups includes the following steps: reacting the thermosetting resin, catalyst, and allylating agent, and drying to obtain the product. The method for preparing the silica sol includes the following steps: mixing tetraethyl orthosilicate and siloxane with a solvent to obtain mixture A; mixing water, a catalyst, and a solvent to obtain mixture B; and reacting mixture A and mixture B to obtain the final product.

3. The novel long-lasting antioxidant and ablation-resistant thermal protective matrix resin according to claim 1, characterized in that, The preparation method of the carborane alkyl material includes the following steps: reacting carborane phenol, phenolic compound with unsaturated bond, aldehyde reagent and catalyst in a solvent, and drying to obtain carborane alkyl material; the mass ratio of carborane phenol, phenolic compound with unsaturated bond and aldehyde reagent is 1:0.5~5:0.5~5.

4. The novel long-lasting antioxidant and ablation-resistant thermal protective matrix resin according to claim 3, characterized in that, The aldehyde reagent is selected from one or more mixtures of aliphatic aldehydes and aromatic aldehydes; The catalyst is one or more of the following: inorganic base, gaseous alkaline substance, aliphatic organic base, and aromatic organic base; The phenolic compounds with unsaturated bonds are phenolic compounds with allyl groups.

5. The novel long-lasting antioxidant and ablation-resistant thermal protective matrix resin according to claim 1, characterized in that, The method for preparing the carboranephenol includes the following steps: Carboranephenol precursor reacts with a demethylating agent to yield carboranephenol; wherein the molar ratio of carboranephenol precursor to demethylating agent is 1:3~12; Among them, R1 is selected from hydrogen, C 1~5 Alkyl, C 2~5 alkenyl, C 1~5 Alkoxy, unsubstituted or R a Substituted 5-6 aryl groups; R2 is selected from hydroxyl protecting groups, silyl protecting groups, ether protecting groups, silyl ether protecting groups, or ester protecting groups; R2 is selected from -LR. b -COR d Not replaced or R c The following groups are substituted: C 1~5 Alkyl, silicon-based; R3 is selected from hydrogen, C 1~5 Alkyl, C 2~5 alkenyl, C 1~5 Alkoxy, unsubstituted or R a Substituted 5-6 aryl groups; R a Selected independently from C 1~5 Alkoxy; R c Independently selected from 5-6 aryl, C 1~5 Alkyl, C 1~5 Alkoxy, -LR b ; L is selected from C 1~5 Alkylene, C 1~5 Alkoxy; R b Independently selected from unsubstituted or R a Substituted 5-6 aryl groups; R d Selected independently from C 1~5 Alkyl, 5-6 aryl, halogen-substituted C 1~5 alkyl.

6. The novel long-lasting antioxidant and ablation-resistant thermal protective matrix resin according to claim 5, characterized in that, The preparation method of the carboranephenol precursor includes the following steps: The decaboron-dodecyl diacetonitrile complex and an alkynyl compound react to yield a carboranephenol precursor; wherein the mass ratio of the decaboron-dodecyl diacetonitrile complex to the alkynyl compound is 1:0.5~2.

5.

7. The novel long-lasting antioxidant and ablation-resistant thermal protective matrix resin according to claim 6, characterized in that, The preparation method of the decaboron-dodecyl diacetonitrile complex includes the following steps: Decaborane and acetonitrile react to yield a decaborane-dodecane-acetonitrile complex; wherein the mass-to-volume ratio of decaborane to acetonitrile is 10-30 g: 50-250 mL.

8. A method for preparing the novel long-lasting antioxidant and ablation-resistant thermal protective matrix resin according to any one of claims 1 to 7, characterized in that, The method includes the following steps: heating and mixing a carborane alkyl material, a thermosetting resin with unsaturated bonds, and a silica sol, drying, and curing to obtain the final product.

9. The method according to claim 8, characterized in that, The heating and mixing conditions are: stirring at 60~100℃ for 1~5 h; the drying conditions are: drying at 60~100℃ for 1~5 h; the curing conditions are: heating at 5~10 MPa pressure with each temperature increasing by 0.2~2 h in a gradient of 120~220℃.

10. The use of the novel long-lasting antioxidant and ablation-resistant thermal protective matrix resin according to any one of claims 1 to 7 in the preparation of thermal protective coatings for long-endurance, ultra-long-range, near-space high-speed aircraft, aerospace reciprocating aircraft, high-temperature resistant thermal protective composite materials, and high-temperature resistant sealant adhesives.

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