Ablation-resistant heat-insulating coating, ablation-resistant heat-insulating coating and preparation method of ablation-resistant heat-insulating coating

Abstract

The invention discloses an ablation-resistant heat-insulating coating, an ablation-resistant heat-insulating coating and a preparation method thereof, and relates to the field of heat-insulating coatings, self-made modified ablation-resistant light filler, modified closed-cell aerogel light heat-insulating filler, fiber reinforced filler, reinforcing filler and a matrix film forming matter are mixed and cured, and the heat-insulating coating capable of being quickly repaired and formed is obtained. The coating obtained by the prepared coating is based on the modified closed-cell aerogel light heat-insulating filler and the modified ablation-resistant light filler, and can realize non-shrinkage rapid curing and high bonding strength with a base material on the basis of keeping excellent three-dimensional structure and performance, and the temperature-resistant heat-insulating performance of the material is improved. In addition, the coating can also be used for repairing defects of coatings of the same type.

Description

Technical Field

[0001] The invention relates to the field of anti-thermal insulation coatings, and in particular to an ablation-resistant thermal insulation coating, an ablation-resistant thermal insulation coating and a preparation method thereof. Background Art

[0002] Thermal insulation coatings have important applications in the field of high-temperature thermal insulation, and can provide thermal protection for the outer surface of materials. As a special type of thermal insulation coating, ablative thermal insulation coatings can dissipate heat through thermal degradation or ablation of the coating itself or the coating formed by coating, thereby achieving thermal protection of the material. Generally speaking, ablative thermal insulation coatings have a simple process, are less affected by product structure, and have low cost and short painting cycles, and are widely used as thermal protection materials. Generally speaking, thermal insulation coating materials have both heat protection and thermal insulation properties, requiring the material to have a low thermal conductivity on the basis of ablation resistance. Unlike other conventional coating materials (thickness is generally <1mm), thermal insulation coatings require a certain thickness to achieve good thermal protection performance, which means that during the preparation, storage and transportation of the coated thermal insulation coating, cracks, dents and other defects may form on the surface of the coating due to bumps and collisions. Therefore, it is necessary to repair the defective parts.

[0003] The repair material usually uses the same type of material as the coating, but because the outer surface of the defective part is irregular, it needs to be polished into a regular area before repairing; at the same time, in order to accelerate curing, the method of simply increasing the curing agent content is generally adopted, which is very easy to form defective large holes due to the too fast curing speed. At the same time, accelerated curing will cause the internal stress of the repair material to be unable to be released, resulting in a large shrinkage as a whole, and then separation from the contact surface, which reduces the bonding strength between the repaired part and the original coating, and there is a risk of falling off during use. In addition, although the silicone-based anti-thermal insulation coating has good ablation resistance, the silicone resin shrinks greatly due to its high cross-linking density, and the material is relatively rigid and has poor wettability with the substrate. It is difficult to give full play to its ablation resistance by conventional use methods. Therefore, by modifying and optimizing the coating composition, a low-shrinkage, compatible anti-thermal insulation coating material that can be used for rapid repair is prepared, which is of great significance for the research and development of high-temperature thermal protection materials. Summary of the invention

[0004] The purpose of the present invention is to provide an ablation-resistant thermal insulation coating, an ablation-resistant thermal insulation coating and a preparation method thereof, so as to solve the problems of large curing shrinkage during repair of the current thermal insulation coating, easy formation of macropores inside thick coating (>1mm), poor film-forming property of silicone resin base glue and poor bonding strength. The ablation-resistant thermal insulation coating that can be used for coating repair replaces the traditional lightweight and thermal insulation fillers with self-made modified ablation-resistant lightweight fillers and modified closed-cell aerogel thermal insulation fillers, respectively, and can effectively resist the shrinkage caused by internal stress while increasing the cross-linking reaction rate of the base glue, and improve the overall compatibility of the coating and the wettability with the substrate. The method of use is simple, and it has important application prospects in the field of thermal insulation coatings.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] In a first aspect, the present invention provides a method for preparing an ablation-resistant thermal insulation coating, the method comprising the following steps:

[0007] (1) First, a modified silicone resin is prepared, and after drying, it is shaken and broken into particles; then, a layer of easily soluble ablative material film is coated on the surface of the particles, and after shaking, it is broken again to prepare a modified ablation-resistant lightweight filler with a core-shell structure;

[0008] (2) firstly preparing ablation-resistant modified aerogel, and then shaking and crushing it after drying; then coating the surface of the crushed material with a layer of insoluble ablative material film, and then shaking and crushing it after drying; then coating the surface of the crushed material with a layer of matrix film-forming material film to prepare a modified closed-cell aerogel lightweight thermal insulation filler with a core-shell structure coated layer by layer;

[0009] (3) According to the weight ratio, 10 to 70 parts of modified ablation-resistant lightweight filler, 5 to 50 parts of modified closed-cell aerogel lightweight thermal insulation filler, 2 to 20 parts of fiber-reinforced filler, 20 to 40 parts of reinforcing filler and 60 to 120 parts of base film-forming material are mixed evenly to prepare an ablation-resistant thermal insulation coating base material;

[0010] (4) Add a curing agent and a diluent to the ablation-resistant thermal insulation coating base material, stir and mix them evenly, and obtain the ablation-resistant thermal insulation coating.

[0011] Preferably, the terminal structure of the modified silicone resin is a mixture of methyl and vinyl.

[0012] Preferably, the particle size of the modified silicone resin is 50-200 μm.

[0013] Preferably, the R chain length of the modified silicone resin is 4 to 12 carbons, more preferably, the R chain length is 6 to 10 carbons.

[0014] Preferably, the R / Si value of the modified silicone resin is 0.8 to 1.4, and more preferably, R / Si is 0.9 to 1.3.

[0015] Preferably, the modified closed-cell aerogel lightweight thermal insulation filler has an organosilicon-based aerogel as a core.

[0016] Preferably, the particle size of the ablation-resistant modified aerogel is ≥ 200 mesh and the density is ≤ 0.20 g / cm 3 , specific surface area ≥300m 2 / g, room temperature thermal conductivity ≤0.03W / (m·K).

[0017] Preferably, the easily soluble ablative material is one of linear phenolic resin, benzoxazine resin, epoxy resin and polyurethane resin.

[0018] Preferably, the insoluble ablative material is one of bulk phenolic resin, silicone rubber and silicone resin.

[0019] Preferably, the substrate film-forming material is one of ablation-resistant modified silicone rubber and modified organic resin.

[0020] Preferably, the thickness of the easily soluble ablative material film is ≤20 μm, and the thickness of the modified ablation-resistant lightweight filler is ≤240 μm.

[0021] Preferably, the thickness of the film of the insoluble ablative material is ≤20 μm, the thickness of the film of the matrix film-forming material is ≤80 μm, and the thickness of the modified closed-cell aerogel lightweight thermal insulation filler is ≤300 μm.

[0022] Preferably, the fiber-reinforced filler is one or more of chopped carbon fiber, chopped quartz fiber, chopped high-silica fiber, and chopped alumina fiber; the chopped fiber has a length of ≤500 μm and a diameter of ≤15 μm.

[0023] Preferably, the reinforcing filler is a compound of one or more of nano-silicon dioxide aerogel, nano-alumina, mica powder, talc powder and one or more of sodium oxide powder, potassium oxide powder, boron oxide powder, iron oxide powder, phosphorus oxide powder, zinc oxide powder, manganese oxide powder and zirconium oxide powder.

[0024] Preferably, the particle size of the reinforcing filler is ≥100 mesh.

[0025] Preferably, in step (1), the powder is dispersed by oscillation through ball milling.

[0026] Preferably, in step (3), during mixing, the viscosity is adjusted by adding a small amount of solvent, and the solvent is one or more of cyclohexane, ethyl acetate, butyl acetate, petroleum ether, No. 60 solvent oil, and No. 120 solvent oil.

[0027] Preferably, in step (3), the modified ablation-resistant lightweight filler is 15 to 60 parts, the modified closed-cell aerogel lightweight insulation filler is 10 to 30 parts, the fiber-reinforced filler is 5 to 15 parts, the reinforcing filler is 25 to 30 parts, and the matrix film-forming material is 70 to 110 parts.

[0028] Preferably, the curing agent is one of organic tin, amines, peroxides, and organic bases. The corresponding curing agent is selected according to the substrate film-forming material used. The amount of curing agent added is calculated by multiplying the amount of all substrate film-forming materials added in steps (1) to (3) by a coefficient of 1.2.

[0029] Preferably, when the curing agent is added, a polar solvent with a mass 2-5 times that of the curing agent is added at the same time, which can dissolve the easily soluble ablative material film material in step (1), and the polar solvent is one of ethanol, methanol, n-pentanol, and isopropanol.

[0030] Preferably, the diluent is a mixture of one or more of ethanol, methanol, and n-pentanol with one or more of acetone, cyclohexane, ethyl acetate, butyl acetate, toluene, xylene, petroleum ether, No. 60 solvent oil, and No. 120 solvent oil.

[0031] Preferably, after the curing agent is added and mixed evenly, the coating should be used within 1 to 2 hours depending on the curing system.

[0032] In a second aspect, the present invention provides an ablation-resistant heat-insulating coating, which is prepared by the method described in the first aspect of the present invention and can be used for defect repair of the same type of coating. The coating is used by diluting the prepared coating with a small amount of diluent into a paste, simply cleaning the defective part to remove excess material, and then using a suitable method such as scraping to fill the defective part and smooth it, and the repair is completed after drying.

[0033] The present invention provides an ablation-resistant thermal insulation coating in a third aspect, which is a coating formed by the ablation-resistant thermal insulation coating prepared by the method described in the first aspect of the present invention. The preparation steps of the coating are: diluting the prepared coating with a diluent to a suitable viscosity, using a suitable brushing method, completing the entire brushing process on the base material, and obtaining a lightweight ablation thermal insulation coating after drying.

[0034] Preferably, the coating method is scraping or spraying.

[0035] Preferably, the drying method is air-drying at room temperature and normal pressure for 2-4 days.

[0036] Compared with the prior art, the method of the present invention has the following beneficial effects:

[0037] (1) The rapidly repairable heat-insulating coating prepared by the present invention uses a self-made modified ablation-resistant lightweight filler as a cross-linking point supplement and stress buffer. The inner core is prepared by partially curing a long-chain organic silicone resin, and the outer shell is an easily soluble thin layer of ablative material film, which is easily soluble in polar solvents such as ethanol. After the inner silicone resin particles are released after mixing, they can be further reacted with the matrix film-forming material with the help of a curing agent, and the cross-linking network points are increased with themselves as nodes, thereby improving the overall cross-linking strength of the coating. In addition, through the end group design, the reaction activity between it and the matrix film-forming material can be improved, and rapid curing and molding can be achieved. At the same time, the long-chain structure of the silicone resin can play a role in buffering stress. On the basis of ensuring the overall high cross-linking density, it will not cause shrinkage of the coating, thereby avoiding the problems of large shrinkage and high rigidity and brittleness of pure silicone resin film-forming materials during curing. At the same time, using a highly wettable organic silicone polymer as the matrix film-forming material, it is unnecessary to regularly polish the repaired part, and the conformability is good and the bonding strength is high.

[0038] (2) The rapidly repairable moldable heat-insulating coating prepared by the present invention uses a self-made modified closed-cell aerogel lightweight heat-insulating filler to replace the traditional hollow microspheres and aerogel heat-insulating fillers. The inner core uses an aerogel made of the same type of organic silicon as the matrix film-forming material or the ablation-resistant heat-insulating filler as the inner core. Different from the conventional aerogel structure, it can ensure the consistency of the coating material and the uniformity of the filler density, and avoid the stratification of the filler due to large differences in density and properties. At the same time, a layer-by-layer coating and gradual dissolution and exposure design is adopted. The outermost layer is a thicker shell film. The material used is the matrix film-forming material, so that the density of the filler itself is similar to that of the matrix film-forming material. During the mixing process, the sedimentation problem of the filler caused by different types can be avoided, the compatibility of the filler and the matrix is ​​improved, and it is conducive to the uniform dispersion of the filler. And the amount of addition has no significant effect on the properties of the coating itself; the sub-outer layer is an ablative material, the shell layer is thin, and can be slightly dissolved by adjusting the polarity of the diluent. After dissolution, it can enhance the compatibility with the film-forming material, and increase the ablation and carbonization components of the coating, which plays a role in bonding and shaping during the use of the coating, and at the same time can protect the open-pore aerogel from being destroyed during the mixing and ablation process. The two shell layers cooperate with each other, and on the basis of improving the dispersion ability and compatibility, they play a lightweight heat-insulating role together with the core layer filler; in addition, the fillers of the coating are made of the same type of silicone material to ensure that the coating has a similar thermal expansion coefficient. During high-temperature use, because the coating used is thicker (>1mm), cracking and shrinkage of the material inside due to thermal mismatch are avoided, thereby ensuring the high-temperature shaping ability of the coating.

[0039] (3) The mixing method of the quick-repairable heat-insulating coating prepared by the present invention is simple, the finished product is uniform and stable, the internal quality of the prepared heat-insulating layer is uniform, there is no significant shrinkage, the room temperature repair curing time is short (1-2h), and the density is low (less than 0.5g / cm 3), room temperature thermal conductivity is 0.05-0.09W / (m·K), room temperature tensile strength is ≥5MPa, temperature resistance is ≥1000℃, service time is ≥800s, or short-term 1300℃, service time is ≤100s, it can maintain a low mass loss rate during service, can effectively reduce the coating surface density, meet the lightweight requirements of anti-insulation materials, and the preparation process is simple, it can be cured and formed alone at low temperature, and can also be used for defect repair of the same type of materials, and has important application prospects in the field of anti-insulation coatings. DETAILED DESCRIPTION

[0040] In order to make the various technical features and advantages or technical effects in the above technical solutions of the present invention more obvious and easy to understand, they are described in detail below in conjunction with embodiments.

[0041] Embodiment 1:

[0042] (1) First, a modified silicone resin having a terminal structure of a methyl-vinyl blend (methyl:vinyl ratio is 1:1) and R having a carbon length of 6 is prepared, and R / Si is controlled to be 0.9. After drying into a block, the block is shaken and broken up, and sieved to obtain particles with a size distribution of 50 to 60 μm; by controlling the reaction time, a layer of linear phenolic resin with a thickness of 10 μm is coated on the outside of the above particles, and after drying, the particles are shaken and broken up again to obtain a modified ablation-resistant lightweight filler with a size of 70 to 80 μm;

[0043] (2) Using the modified silicone resin in step (1) as a precursor, preparing an organic silicon-based ablation-resistant modified aerogel, shaking and breaking it up after drying, and sieving to obtain aerogel particles with a particle size of 200 mesh (density of 0.18 g / cm 3 , with a specific surface area of ​​350m 2 / g); by controlling the reaction time, coating the above particles with a layer of 20 μm thick boron phenolic resin; after drying, oscillating and breaking up again, and then coating the broken particles with a layer of 80 μm thick modified silicone resin (1), oscillating and breaking up, to prepare a modified closed-cell aerogel lightweight insulation filler with a size of 260 to 280 μm;

[0044] (3) 70 g of modified ablation-resistant lightweight filler, 50 g of modified closed-cell aerogel lightweight thermal insulation filler, 120 g of modified silicone rubber, 10 g of nano-alumina, 10 g of mica powder, 10 g of boron oxide, 10 g of potassium oxide, 8 g of chopped quartz fiber, and 10 g of chopped high-silicon phenolic fiber were mixed evenly, and 20 g of No. 120 solvent oil was added during the mixing to adjust the viscosity to prepare an ablation-resistant thermal insulation coating base material;

[0045] (4) Add 7.2 g of dibutyltin dilaurate and 35 g of ethanol to the above coating base, stir and mix evenly to obtain an ablation-resistant thermal insulation coating.

[0046] The above paint was diluted with No. 120 solvent oil, then applied to 5mm thick coating components, dried at room temperature for 3 days, and then relevant assessments were carried out.

[0047] Product performance test: The prepared coating has no obvious shrinkage and the density is 0.45g / cm 3 The room temperature thermal conductivity is 0.083W / (m·K), the greenhouse tensile strength is 7.2MPa, it can withstand 1000℃ oxyacetylene test for 900s, and the outer surface of the coating remains intact after the test.

[0048] Embodiment 2:

[0049] (1) First, a modified silicone resin having a terminal structure of a methyl-vinyl blend (methyl:vinyl ratio is 1:1) and R having a carbon length of 10 is prepared, and R / Si is controlled to be 1.1. After drying into a block, the block is shaken and broken up, and sieved to obtain particles with a size distribution of 100 to 120 μm; by controlling the reaction time, a layer of benzoxazine resin with a thickness of 20 μm is coated on the outside of the above particles, and after drying, the particles are shaken and broken up again to obtain a modified ablation-resistant lightweight filler with a size of 140 to 160 μm;

[0050] (2) Using the modified silicone resin in step (1) as a precursor, a silicone-based ablation-resistant modified aerogel is prepared, which is then shaken and broken up after drying, and sieved to obtain aerogel particles with a particle size of 200 mesh (density of 0.19 g / cm 3 , with a specific surface area of ​​320m 2 / g); by controlling the reaction time, coating the above particles with a layer of 15 μm thick boron phenolic resin; after drying, oscillating and breaking up again, and then coating the broken particles with a layer of 60 μm thick modified silicone resin (1), oscillating and breaking up, to prepare a modified closed-cell aerogel lightweight insulation filler with a size of 220 to 240 μm;

[0051] (3) 70 g of modified ablation-resistant lightweight filler, 50 g of modified closed-cell aerogel lightweight thermal insulation filler, 120 g of modified silicone resin, 10 g of nano-alumina, 10 g of mica powder, 10 g of boron oxide, 10 g of potassium oxide, 8 g of chopped quartz fiber, and 10 g of chopped high-silicon phenolic fiber were mixed evenly, and 20 g of No. 120 solvent oil was added during the mixing to adjust the viscosity to prepare an ablation-resistant thermal insulation coating base material;

[0052] (4) Add 3.2 g of tetramethylammonium hydroxide and 15 g of methanol to the above coating base, stir and mix evenly to obtain ablation-resistant thermal insulation coating.

[0053] The above paint was diluted with No. 120 solvent oil, then applied to 5mm thick coating components, dried at room temperature for 3 days, and then relevant assessments were carried out.

[0054] Product performance test: The prepared coating has no obvious shrinkage and the density is 0.47g / cm 3 The room temperature thermal conductivity is 0.085W / (m·K), the greenhouse tensile strength is 7.5MPa, it can withstand 1000℃ oxyacetylene test for 900s, and the outer surface of the coating remains intact after the test.

[0055] Embodiment 3:

[0056] (1) First, a modified silicone resin having a terminal structure of a methyl-vinyl blend (methyl:vinyl ratio of 2:1) and R of 12 carbon atoms is prepared, and R / Si is controlled to be 1.3. After drying into blocks, the blocks are shaken and broken up, and sieved to obtain particles with a size distribution of 180 to 200 μm; by controlling the reaction time, a layer of polyurethane resin with a thickness of 20 μm is coated on the outside of the above particles, and after drying, the particles are shaken and broken up again to obtain a modified ablation-resistant lightweight filler with a size of 220 to 240 μm;

[0057] (2) Using the modified silicone resin in step (1) as a precursor, preparing an organic silicon-based ablation-resistant modified aerogel, shaking and breaking it up after drying, and sieving to obtain aerogel particles with a particle size of 200 mesh (density of 0.17 g / cm 3 , with a specific surface area of ​​320m 2 / g); by controlling the reaction time, coating the above particles with a layer of room temperature vulcanized silicone rubber with a thickness of 15 μm; after drying, oscillating and breaking up again, and then coating the broken up particles with a layer of modified silicone resin in (1) with a thickness of 50 μm, oscillating and breaking up, to prepare a modified closed-cell aerogel lightweight thermal insulation filler with a size of 140 to 160 μm;

[0058] (3) 70 g of modified ablation-resistant lightweight filler, 50 g of modified closed-cell aerogel lightweight thermal insulation filler, 120 g of modified silicone resin, 10 g of nano-alumina, 10 g of mica powder, 10 g of boron oxide, 10 g of potassium oxide, 8 g of chopped quartz fiber, and 10 g of chopped high-silicon phenolic fiber were mixed evenly, and 20 g of No. 120 solvent oil was added during the mixing to adjust the viscosity to prepare an ablation-resistant thermal insulation coating base material;

[0059] (4) Add 14.4 g of tetrabutyl titanate and 35 g of n-pentanol to the above-mentioned coating base material, stir and mix evenly to obtain an ablation-resistant thermal insulation coating.

[0060] The above paint was diluted with No. 120 solvent oil, then applied to 5mm thick coating components, dried at room temperature for 3 days, and then relevant assessments were carried out.

[0061] Product performance test: The prepared coating has no obvious shrinkage and the density is 0.46g / cm 3The room temperature thermal conductivity is 0.075W / (m·K), the greenhouse tensile strength is 6.5MPa, it can withstand 1000℃ oxyacetylene test for 900s, and the outer surface of the coating remains intact after the test.

[0062] Embodiment 4:

[0063] (1) First, a modified silicone resin having a terminal structure of a methyl-vinyl blend (methyl:vinyl ratio of 2:1) and R of 10 carbon atoms is prepared, and R / Si is controlled to be 1.0. After drying into blocks, the blocks are shaken and broken up, and sieved to obtain particles with a size distribution of 150 to 180 μm; by controlling the reaction time, a layer of epoxy resin with a thickness of 15 μm is coated on the outside of the above particles, and after drying, the particles are shaken and broken up again to obtain a modified ablation-resistant lightweight filler with a size of 180 to 210 μm;

[0064] (2) Using the modified silicone resin in step (1) as a precursor, a silicone-based ablation-resistant modified aerogel is prepared, which is then shaken and broken up after drying, and sieved to obtain aerogel particles with a particle size of 200 mesh (density of 0.16 g / cm 3 , with a specific surface area of ​​370m 2 / g); by controlling the reaction time, coating the above particles with a layer of room temperature vulcanized silicone rubber with a thickness of 15 μm; after drying, oscillating and breaking up again, and then coating the broken up particles with a layer of modified silicone resin in (1) with a thickness of 50 μm, oscillating and breaking up, to prepare a modified closed-cell aerogel lightweight thermal insulation filler with a size of 140 to 160 μm;

[0065] (3) 60 g of modified ablation-resistant lightweight filler, 30 g of modified closed-cell aerogel lightweight thermal insulation filler, 110 g of modified silicone resin, 5 g of nano-alumina, 5 g of mica powder, 5 g of boron oxide, 5 g of potassium oxide, 5 g of zinc oxide, 5 g of zirconium oxide, 7 g of short-cut quartz fiber, and 8 g of short-cut high-silicon phenolic fiber were mixed evenly, and 30 g of No. 120 solvent oil was added during the mixing to adjust the viscosity to prepare an ablation-resistant thermal insulation coating base material;

[0066] (4) Add 12.5 g of tetrabutyl titanate and 50 g of ethanol to the above-mentioned coating base material, stir and mix evenly to obtain an ablation-resistant thermal insulation coating.

[0067] The above paint was diluted with No. 120 solvent oil, then applied to 5mm thick coating components, dried at room temperature for 3 days, and then relevant assessments were carried out.

[0068] Product performance test: The prepared coating has no obvious shrinkage and the density is 0.35g / cm 3 The room temperature thermal conductivity is 0.055W / (m·K), the greenhouse tensile strength is 8.7MPa, it can withstand 1000℃ oxyacetylene test for 900s, and the outer surface of the coating remains intact after the test.

[0069] Embodiment 5:

[0070] (1) First, a modified silicone resin having a terminal structure of a methyl-vinyl blend (methyl:vinyl ratio of 2:1) and R of 10 carbon atoms is prepared, and R / Si is controlled to be 1.0. After drying into blocks, the blocks are shaken and broken up, and sieved to obtain particles with a size distribution of 150 to 180 μm; by controlling the reaction time, a layer of epoxy resin with a thickness of 15 μm is coated on the outside of the above particles, and after drying, the particles are shaken and broken up again to obtain a modified ablation-resistant lightweight filler with a size of 180 to 210 μm;

[0071] (2) Using the modified silicone resin in step (1) as a precursor, a silicone-based ablation-resistant modified aerogel is prepared, which is then shaken and broken up after drying, and sieved to obtain aerogel particles with a particle size of 200 mesh (density of 0.16 g / cm 3 , with a specific surface area of ​​370m 2 / g); by controlling the reaction time, coating the above particles with a layer of room temperature vulcanized silicone rubber with a thickness of 15 μm; after drying, oscillating and breaking up again, and then coating the broken up particles with a layer of modified silicone resin in (1) with a thickness of 50 μm, oscillating and breaking up, to prepare a modified closed-cell aerogel lightweight thermal insulation filler with a size of 140 to 160 μm;

[0072] (3) 15 g of modified ablation-resistant lightweight filler, 10 g of modified closed-cell aerogel lightweight thermal insulation filler, 70 g of modified silicone resin, 5 g of nano-alumina, 2 g of mica powder, 5 g of boron oxide, 3 g of potassium oxide, 5 g of zinc oxide, 5 g of zirconium oxide, 2 g of short-cut quartz fiber, and 3 g of short-cut high-silicon phenolic fiber were mixed evenly, and 30 g of No. 120 solvent oil was added during the mixing to adjust the viscosity to prepare an ablation-resistant thermal insulation coating base material;

[0073] (4) Add 3.5 g of tetrabutyl titanate and 16.8 g of ethanol to the above-mentioned coating base material, stir and mix evenly to obtain an ablation-resistant thermal insulation coating.

[0074] The above paint was diluted with No. 120 solvent oil, then applied to 5mm thick coating components, dried at room temperature for 3 days, and then relevant assessments were carried out.

[0075] Product performance test: The prepared coating has no obvious shrinkage and the density is 0.34g / cm 3 The room temperature thermal conductivity is 0.055W / (m·K), the greenhouse tensile strength is 8.5MPa, it can withstand 1000℃ oxyacetylene test for 900s, and the outer surface of the coating remains intact after the test.

[0076] Comparative Example 1:

[0077] (1) 120 g of silicone rubber, 40 g of hollow microspheres, 10 g of nano-alumina, 10 g of mica powder, 10 g of boron oxide, 10 g of potassium oxide, 8 g of chopped quartz fiber, and 10 g of chopped high-silicon phenolic fiber were mixed evenly, and 20 g of No. 120 solvent oil was added during the mixing to adjust the viscosity to prepare an ablation-resistant thermal insulation coating base material;

[0078] (4) Add 6 g of dibutyltin dilaurate and 35 g of ethanol to the above coating base, stir and mix evenly to obtain an ablation-resistant thermal insulation coating.

[0079] The above paint was diluted with No. 120 solvent oil, then applied to 5mm thick coating components, dried at room temperature for 3 days, and then relevant assessments were carried out.

[0080] Product performance test: The shrinkage rate of the prepared coating is 6.8% and the density is 0.35g / cm 3 The room temperature thermal conductivity is 0.053W / (m·K), the greenhouse tensile strength is 0.5MPa, and the coating surface cracks and falls off after 1000℃ oxyacetylene test for 900s.

[0081] Comparative Example 2:

[0082] (1) 120 g of silicone resin, 20 g of hollow microspheres, 30 g of silica aerogel, 10 g of nano-alumina, 10 g of mica powder, 10 g of boron oxide, 10 g of potassium oxide, 8 g of chopped quartz fiber, and 10 g of chopped high-silicon phenolic fiber were mixed evenly, and 20 g of No. 120 solvent oil was added during the mixing to adjust the viscosity to prepare an ablation-resistant thermal insulation coating base material;

[0083] (4) Add 12 g of tetrabutyl titanate and 35 g of ethanol to the above coating base, stir and mix evenly to obtain an ablation-resistant thermal insulation coating.

[0084] The above paint was diluted with No. 120 solvent oil, then applied to 5mm thick coating components, dried at room temperature for 3 days, and then relevant assessments were carried out.

[0085] Product performance test: The shrinkage rate of the prepared coating is 8% and the density is 0.30g / cm 3 The room temperature thermal conductivity is 0.050W / (m·K), the greenhouse tensile strength is 0.6MPa, and the coating surface cracks and falls off after 1000℃ oxyacetylene test for 900s.

[0086] It can be seen from the above-mentioned Examples 1-5 and Comparative Examples 1-2 that, compared with the comparative examples, the embodiments are different from the comparative examples in that the modified ablation-resistant lightweight filler and the modified closed-cell aerogel lightweight thermal insulation filler are prepared through the first two steps, and the filler is mixed with the coating base material. After the coating is made into a coating product, the cross-linking reaction rate is increased, and the shrinkage caused by internal stress can be effectively resisted, and the overall compatibility of the coating and the wettability with the substrate are improved.

[0087] Although the present invention has been disclosed as above by way of embodiments, it is not intended to limit the present invention. Appropriate modifications or equivalent substitutions of the technical solutions of the present invention made by ordinary technicians in the field should all be included in the protection scope of the present invention. The protection scope of the present invention shall be based on what is defined in the claims.

Claims

1. A method for preparing an ablation-resistant thermal insulation coating, characterized in that: The following steps are involved: (1) First, a modified silicone resin is prepared, and after drying, it is shaken and broken into particles; then, a layer of easily soluble ablative material film is coated on the surface of the particles, and after shaking, it is broken again to prepare a modified ablation-resistant lightweight filler with a core-shell structure; (2) first preparing ablation-resistant modified aerogel, and then shaking and crushing it after drying; Then, a layer of insoluble ablative material film is coated on the surface of the crushed material, and the material is shaken and crushed after drying; then, a layer of matrix film-forming material film is coated on the surface of the crushed material to prepare a modified closed-cell aerogel lightweight thermal insulation filler with a core-shell structure coated layer by layer; (3) According to the weight ratio, 10 to 70 parts of modified ablation-resistant lightweight filler, 5 to 50 parts of modified closed-cell aerogel lightweight thermal insulation filler, 2 to 20 parts of fiber-reinforced filler, 20 to 40 parts of reinforcing filler and 60 to 120 parts of base film-forming material are mixed evenly to prepare an ablation-resistant thermal insulation coating base material; (4) Add a curing agent and a diluent to the ablation-resistant thermal insulation coating base material, stir and mix them evenly, and obtain the ablation-resistant thermal insulation coating.

2. The method according to claim 1, characterized in that The terminal structure of the modified silicone resin is a mixture of methyl and vinyl, the particle size of the modified silicone resin is 50-200 μm, the R chain length of the modified silicone resin is 4-12 carbons, and the R / Si value of the modified silicone resin is 0.8-1.

4.

3. The method according to claim 1, characterized in that The particle size of the ablation-resistant modified aerogel is ≥200 mesh and the density is ≤0.20g / cm 3 , specific surface area ≥300m 2 / g, room temperature thermal conductivity ≤0.03W / (m·K).

4. The preparation method according to claim 1, characterized in that: The easily soluble ablative material is one of linear phenolic resin, benzoxazine resin, epoxy resin and polyurethane resin; the thickness of the easily soluble ablative material film is ≤20μm, and the thickness of the modified ablative resistant lightweight filler is ≤240μm; The insoluble ablative material is one of bulk phenolic resin, silicone rubber, and silicone resin; the film thickness of the insoluble ablative material is ≤20μm, the film thickness of the matrix film-forming material is ≤80μm, and the modified closed-cell aerogel lightweight insulation filler is ≤300μm.

5. The method according to claim 1, characterized in that The fiber-reinforced filler is one or more of chopped carbon fiber, chopped quartz fiber, chopped high-silica fiber, and chopped alumina fiber; wherein the chopped fiber has a length of ≤500 μm and a diameter of ≤15 μm; The reinforcing filler is a compound of one or more of nano-silicon dioxide aerogel, nano-alumina, mica powder, talc powder and one or more of sodium oxide powder, potassium oxide powder, boron oxide powder, iron oxide powder, phosphorus oxide powder, zinc oxide powder, manganese oxide powder, and zirconium oxide powder; the particle size of the reinforcing filler is ≥100 mesh; In steps (2) and (3), the substrate film-forming material is one of ablation-resistant modified silicone rubber and modified organic resin.

6. The method according to claim 1, characterized in that In step (3), during mixing, the viscosity is adjusted by adding a solvent, and the solvent is one or more of cyclohexane, ethyl acetate, butyl acetate, petroleum ether, No. 60 solvent oil, and No. 120 solvent oil.

7. The method according to claim 1, characterized in that In step (3), the modified ablation-resistant lightweight filler is 15 to 60 parts, the modified closed-cell aerogel lightweight insulation filler is 10 to 30 parts, the fiber-reinforced filler is 5 to 15 parts, the reinforcing filler is 25 to 30 parts, and the matrix film-forming material is 70 to 110 parts.

8. The method according to claim 1, characterized in that The curing agent is one of organic tin, amine, peroxide, and organic base, and the amount of the curing agent added is calculated by multiplying the amount of the total amount of the substrate film-forming material added in steps (1) to (3) by a coefficient of 1.2; When the curing agent is added, a polar solvent of 2-5 times the mass of the curing agent is added at the same time, and the polar solvent is one of ethanol, methanol, n-pentanol, and isopropanol; The diluent is a mixture of one or more of ethanol, methanol, and n-pentanol with one or more of acetone, cyclohexane, ethyl acetate, butyl acetate, toluene, xylene, petroleum ether, No. 60 solvent oil, and No. 120 solvent oil.

9. An ablation-resistant thermal insulation coating, characterized in that: Prepared by the method according to any one of claims 1 to 8.

10. An ablation-resistant thermal insulation coating, characterized in that: The ablation-resistant thermal insulation coating is prepared by the method according to any one of claims 1 to 8.