A multilayer composite structure heat shield coating for heat shields and a method of making the same

Abstract

The application provides a multilayer composite structure heat-proof coating for a heat-proof skirt and a preparation method thereof, which comprises a base cloth layer, a base layer, an intermediate layer and a surface layer which are sequentially stacked; the base layer preparation raw materials comprise: 100 parts of methyl vinyl silicone rubber, 20-55 parts of first compounded halogen-free flame retardant, 0.5-5 parts of vulcanizing agent and 2-12 parts of first heat-resistant modifier; the intermediate layer preparation raw materials comprise: 95-105 parts of methyl vinyl silicone rubber, 65-100 parts of second compounded halogen-free flame retardant and 5-30 parts of second heat-resistant modifier; and the surface layer preparation raw materials comprise: 5-20 parts of third heat-resistant modifier, 0.5-3 parts of zirconium oxide and 2-9 parts of aluminum oxide. The heat-proof coating adopts a multilayer composite structure design, the rubber proportion of the base layer is larger, the base layer provides basic flexibility and chemical stability for the coating, the proportion of the compounded halogen-free flame retardant of the intermediate layer is more than that of the base layer, the flame retardancy and heat insulation property are enhanced, and the surface layer radiation-resistant coating can improve the radiation heat dissipation capacity.

Description

Technical Field

[0001] This invention belongs to the field of heat protection skirt technology for aerospace engines, specifically relating to a multi-layer composite structure heat protection coating for heat protection skirts and its preparation method. Background Technology

[0002] In the field of aerospace engine protection, thermal skirts play a crucial role. Thermal skirts are the external heat-insulating components surrounding aerospace engines, used to block high-temperature airflow and radiant heat, protecting the surrounding engine structure from thermal damage. Currently, traditional thermal skirts mainly use carbon fiber composite materials. While these materials possess certain heat resistance, they lack flexibility and are unable to adapt to the dynamic deformation caused by engine oscillations. During actual engine operation, oscillations subject the thermal skirt to various forces such as stretching and expansion. Due to the poor flexibility of the material, it is prone to cracking and damage, thus affecting the protective effect. Some flexible materials, such as ordinary silicone rubber-coated fabrics, are used. For example, Chinese patent document CN109719970B discloses a thermal skirt and its preparation method, which is prepared by coating a glass fiber prepreg with liquid silicone rubber. Although they possess good flexibility and can adapt to dynamic deformation to some extent, their flame retardancy rating is low. In high-temperature exhaust environments, these materials are easily combustible or decomposed, failing to provide effective protection for the engine and seriously threatening its safe operation. Furthermore, some existing flame-retardant coatings use halogen-containing flame-retardant systems, which release toxic gases during combustion, failing to meet environmental protection requirements. Furthermore, many coatings perform poorly in terms of high-temperature, short-term ablation resistance, failing to maintain integrity for more than 30 seconds under a heat flux of 800 kW / m². These technical bottlenecks and practical application obstacles limit the development of engine protection technology, thus necessitating a new technology to address these issues. Summary of the Invention

[0003] The technical problem solved by this invention is to provide a multi-layer composite structure heat-resistant coating for heat-resistant skirts and its preparation method. The multi-layer composite structure design adopts a base layer with a silicone rubber coating with a higher rubber content to provide basic flexibility and chemical stability for the coating. The middle layer is compounded with a higher proportion of halogen-free flame retardant than the base layer to enhance flame retardant and heat insulation performance. The surface layer adopts an anti-radiation coating to improve radiative heat dissipation capacity.

[0004] To address the above problems, one aspect of the present invention provides a multi-layer composite heat-resistant coating for heat-resistant skirts, comprising a base fabric layer, a base layer, an intermediate layer, and a surface layer stacked sequentially.

[0005] The raw materials for preparing the base layer include the following components in parts by weight: 100 parts of methyl vinyl silicone rubber, 20-55 parts of the first compound halogen-free flame retardant, 0.5-5 parts of vulcanizing agent, and 2-12 parts of the first heat-resistant modifier;

[0006] The raw materials for preparing the intermediate layer include the following components in parts by weight: 95-105 parts of methyl vinyl silicone rubber, 65-100 parts of the second compounded halogen-free flame retardant, and 5-30 parts of the second heat-resistant modifier.

[0007] The raw materials for preparing the surface layer include the following components in parts by weight: 5-20 parts of the third heat-resistant modifier, 0.5-3 parts of zirconium oxide, and 2-9 parts of alumina.

[0008] Preferably, the raw materials for preparing the base layer include the following components in parts by weight: 100 parts of methyl vinyl silicone rubber, 30-50 parts of the first compound halogen-free flame retardant, 1-3 parts of vulcanizing agent, and 5-10 parts of the first heat-resistant modifier;

[0009] The raw materials for preparing the intermediate layer include the following components in parts by weight: 95-105 parts of methyl vinyl silicone rubber, 70-90 parts of the second compounded halogen-free flame retardant, and 10-20 parts of the second heat-resistant modifier.

[0010] The raw materials for preparing the surface layer include the following components in parts by weight: 10-15 parts of the third heat-resistant modifier, 1-2 parts of zirconium oxide, and 4-7 parts of alumina.

[0011] Preferably, the raw materials for preparing the base layer further include the following components in parts by weight: 15-25 parts of fumed silica and 5-15 parts of chopped carbon fiber.

[0012] Preferably, the raw materials for preparing the first compound halogen-free flame retardant and / or the second compound halogen-free flame retardant include the following components in parts by weight: 25-40 parts of intumescent flame retardant, 5-10 parts of antimony trioxide, and 3-5 parts of nano-alumina; wherein the intumescent flame retardant is one or a combination of two of ammonium polyphosphate and pentaerythritol.

[0013] Preferably, the vulcanizing agent is a platinum catalyst; the first heat-resistant modifier and / or the second heat-resistant modifier and / or the third heat-resistant modifier are polyimide resins.

[0014] Preferably, the thickness of the base layer is 0.2~0.3mm; the thickness of the intermediate layer is 0.3~0.5mm; and the thickness of the surface layer is 0.1~0.2mm.

[0015] Preferably, the upper surface of the surface layer is corrugated or pleated.

[0016] Another aspect of the present invention provides a method for preparing the above-mentioned multilayer composite structure heat-resistant coating for heat-resistant skirts, comprising the following steps:

[0017] S1. Mix the raw materials for the preparation of the base layer to obtain the base layer slurry, apply the base layer slurry to the surface of the base fabric, and then vulcanize it at high temperature to form the base layer;

[0018] S2. Mix the raw materials for preparing the intermediate layer to obtain an intermediate layer slurry, and place the intermediate layer slurry on the surface of the base layer to form an intermediate layer;

[0019] S3. Mix the raw materials for the preparation of the surface layer to obtain a surface slurry, and set the surface slurry on the surface of the intermediate layer to form the surface layer;

[0020] S4. Press the obtained structure together and then cure it to obtain the multi-layer composite heat-resistant coating for the heat-resistant skirt.

[0021] Preferably, before pressing, a corrugated PE film is placed on the upper surface of the surface layer, and after pressing, a corrugated shape is formed on the upper surface of the surface layer; or before pressing, a pleated PE film is placed on the upper surface of the surface layer, and after pressing, a pleated shape is formed on the upper surface of the surface layer.

[0022] Preferably, in step S1, the high-temperature vulcanization temperature is 150~180℃ and the time is 10 min.

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] The multi-layer composite heat-resistant coating for the heat-resistant skirt of this invention employs a multi-layer composite structure design. The base layer uses a silicone rubber coating with a higher rubber content to provide flexibility, better adapting to dynamic deformation caused by engine oscillation and avoiding cracking due to excessive material rigidity, thus ensuring the integrity and protective performance of the heat-resistant skirt in dynamic environments. Addressing the issue of low flame retardancy ratings in some flexible materials, the middle layer of this multi-layer composite heat-resistant coating uses a flame-retardant silicone rubber matrix with a higher proportion of compounded halogen-free flame retardants, enhancing flame retardancy. Furthermore, the middle layer has a higher proportion of flame retardants than the base layer. Because the flame retardant is a powder, it can form a micro-nano porous structure, thereby enhancing heat insulation performance. In high-temperature combustion environments, it effectively prevents material combustion or decomposition, providing reliable protection for the engine. Existing halogen-containing flame-retardant systems release toxic gases; the multi-layer composite heat-resistant coating of this invention uses a halogen-free flame-retardant system, avoiding the release of toxic gases during combustion, meeting environmental protection requirements, and reducing harm to the environment and personnel. The zirconium oxide / alumina composite coating formed on the surface has radiation resistance properties, improving radiative heat dissipation capacity. Among them, vulcanizing agents can promote the vulcanization reaction of rubber. Heat-resistant modifiers can further improve the heat resistance of the coating. Detailed Implementation

[0025] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0026] One aspect of the present invention provides a multi-layer composite heat-resistant coating for a heat-resistant skirt, comprising a base fabric layer, a base layer, an intermediate layer and a surface layer stacked sequentially;

[0027] The raw materials for preparing the base layer include the following components in parts by weight: 100 parts of methyl vinyl silicone rubber, 20-55 parts of the first compound halogen-free flame retardant, 0.5-5 parts of vulcanizing agent, and 2-12 parts of the first heat-resistant modifier;

[0028] The raw materials for preparing the intermediate layer include the following components in parts by weight: 95-105 parts of methyl vinyl silicone rubber, 65-100 parts of the second compounded halogen-free flame retardant, and 5-30 parts of the second heat-resistant modifier.

[0029] The raw materials for preparing the surface layer include the following components in parts by weight: 5-20 parts of the third heat-resistant modifier, 0.5-3 parts of zirconium oxide, and 2-9 parts of alumina.

[0030] This invention relates to a multi-layer composite heat-resistant coating for a heat-resistant skirt. The base layer uses a silicone rubber coating with a higher rubber content to provide flexibility, better adapting to dynamic deformation caused by engine oscillations and preventing cracking due to excessive material rigidity. This ensures the integrity and protective performance of the heat-resistant skirt under dynamic conditions. Addressing the issue of low flame retardancy ratings in some flexible materials, the middle layer of this multi-layer composite heat-resistant coating uses a flame-retardant silicone rubber matrix with a higher proportion of compounded halogen-free flame retardants, enhancing flame retardancy. Furthermore, the middle layer has a higher proportion of flame retardants than the base layer. Because the flame retardant is a powder, it can form a micro-nano porous structure, thereby enhancing heat insulation performance. In high-temperature combustion environments, it effectively prevents material combustion or decomposition, providing reliable protection for the engine. Existing halogen-containing flame-retardant systems release toxic gases. This invention's multi-layer composite heat-resistant coating uses a halogen-free flame-retardant system, avoiding the release of toxic gases during combustion, meeting environmental protection requirements, and reducing harm to the environment and personnel. The zirconium oxide / alumina composite coating formed on the surface has radiation resistance properties, improving radiative heat dissipation. Among them, vulcanizing agents can promote the vulcanization reaction of rubber. Heat-resistant modifiers can further improve the heat resistance of the coating.

[0031] Preferably, the raw materials for preparing the base layer include the following components in parts by weight: 100 parts of methyl vinyl silicone rubber, 30-50 parts of the first compound halogen-free flame retardant, 1-3 parts of vulcanizing agent, and 5-10 parts of the first heat-resistant modifier;

[0032] The raw materials for preparing the intermediate layer include the following components in parts by weight: 95-105 parts of methyl vinyl silicone rubber, 70-90 parts of the second compounded halogen-free flame retardant, and 10-20 parts of the second heat-resistant modifier.

[0033] The raw materials for preparing the surface layer include the following components in parts by weight: 10-15 parts of the third heat-resistant modifier, 1-2 parts of zirconium oxide, and 4-7 parts of alumina.

[0034] The multi-layer composite structure heat-resistant coating for the heat-resistant skirt of the present invention, through further optimization of the formula, can make the coating have more suitable flexibility, better flame retardant properties, better heat insulation properties and ablation resistance, so that the coating can maintain its integrity for ≥30 seconds under a heat flow of 800kw / ㎡, which improves the coating's protective ability in extreme high temperature environments and ensures the safe and stable operation of the engine.

[0035] Preferably, the vinyl content in the methyl vinyl silicone rubber is 0.15% to 0.3%.

[0036] Preferably, the raw materials for preparing the base layer further include the following components in parts by weight: 15-25 parts of fumed silica and 5-15 parts of chopped carbon fiber.

[0037] The addition of fumed silica and chopped carbon fibers can further improve the mechanical properties of multilayer composite heat-resistant coatings.

[0038] Preferably, the raw materials for preparing the first compound halogen-free flame retardant and / or the second compound halogen-free flame retardant include the following components in parts by weight: 25-40 parts of intumescent flame retardant, 5-10 parts of antimony trioxide, and 3-5 parts of nano-alumina; wherein the intumescent flame retardant is one or a combination of two of ammonium polyphosphate and pentaerythritol.

[0039] Intumescent flame retardants can expand at high temperatures to form a heat insulation layer; antimony trioxide and nano-alumina are synergists that can further enhance the flame retardant effect, avoiding the use of halogenated flame retardants.

[0040] Preferably, the vulcanizing agent is a platinum catalyst; the first heat-resistant modifier and / or the second heat-resistant modifier and / or the third heat-resistant modifier are polyimide resins.

[0041] Preferably, the thickness of the base layer is 0.2~0.3mm; the thickness of the intermediate layer is 0.3~0.5mm; and the thickness of the surface layer is 0.1~0.2mm. The multi-layer composite heat-resistant coating for the heat-resistant skirt of the present invention, by further optimizing the thickness of each layer, enables the entire coating to possess more suitable flexibility, better flame retardant properties, better heat insulation properties, and ablation resistance.

[0042] Preferably, the upper surface of the surface layer is corrugated or wrinkled. A corrugated or wrinkled upper surface helps the coating maintain its integrity under axial tension and radial expansion, adapting to deformation caused by engine oscillation.

[0043] Another aspect of the present invention provides a method for preparing the above-mentioned multilayer composite structure heat-resistant coating for heat-resistant skirts, comprising the following steps:

[0044] S1. Mix the raw materials for the preparation of the base layer to obtain the base layer slurry, apply the base layer slurry to the surface of the base fabric, and then vulcanize it at high temperature to form the base layer;

[0045] S2. Mix the raw materials for preparing the intermediate layer to obtain an intermediate layer slurry, and place the intermediate layer slurry on the surface of the base layer to form an intermediate layer;

[0046] S3. Mix the raw materials for the preparation of the surface layer to obtain a surface slurry, and set the surface slurry on the surface of the intermediate layer to form the surface layer;

[0047] S4. Press the obtained structure together and then cure it to obtain the multi-layer composite heat-resistant coating for the heat-resistant skirt.

[0048] Preferably, before pressing, a corrugated PE film is placed on the upper surface of the surface layer, and after pressing, a corrugated shape is formed on the upper surface of the surface layer; or before pressing, a pleated PE film is placed on the upper surface of the surface layer, and after pressing, a pleated shape is formed on the upper surface of the surface layer.

[0049] Preferably, in step S1, the high-temperature vulcanization temperature is 150~180℃ and the time is 10 min.

[0050] In the following embodiments, the platinum catalyst is the delayed platinum Ashby catalyst PT5000-VMC1000.

[0051] Example 1

[0052] The heat-resistant skirt of this embodiment uses a multi-layer composite structure heat-resistant coating, which includes a base fabric layer (alkali-free glass fiber cloth EW50), a base layer, an intermediate layer and a surface layer stacked in sequence.

[0053] The base layer is prepared from the following components in parts by weight: 100 parts methyl vinyl silicone rubber (vinyl content 0.15%), 30 parts the first compound halogen-free flame retardant, 1 part platinum catalyst, 5 parts polyimide resin, 20 parts fumed silica, and 5 parts chopped carbon fiber. The first compound halogen-free flame retardant is prepared from the following components in parts by weight: 25 parts ammonium polyphosphate, 5 parts antimony trioxide, and 3 parts nano-alumina. The base layer has a thickness of 0.2 mm.

[0054] The intermediate layer is prepared from the following components in parts by weight: 100 parts of methyl vinyl silicone rubber (vinyl content 0.15%), 80 parts of the second compounded halogen-free flame retardant, and 10 parts of polyimide resin. The second compounded halogen-free flame retardant is prepared from the following components in parts by weight: 25 parts of ammonium polyphosphate, 5 parts of antimony trioxide, and 3 parts of nano-alumina. The thickness of the intermediate layer is 0.3 mm.

[0055] The surface layer is prepared using the following components in parts by weight: 10 parts polyimide resin, 1 part zirconium oxide, and 4 parts alumina. The surface layer has a thickness of 0.1 mm. The upper surface of the surface layer is corrugated.

[0056] The method for preparing the multi-layer composite structure heat-resistant coating for the heat-resistant skirt in this embodiment includes the following steps:

[0057] S1. Mix the raw materials for the preparation of the base layer to obtain the base layer slurry. Apply the base layer slurry evenly to the surface of the base fabric by scraping. Then, vulcanize at 150°C for 10 minutes to form the base layer with a thickness of 0.2 mm.

[0058] S2. Mix the raw materials for the preparation of the intermediate layer to obtain an intermediate layer slurry. Apply the intermediate layer slurry evenly to the surface of the base layer using a scraping method to form an intermediate layer with a thickness of 0.3 mm.

[0059] S3. Mix the raw materials for the preparation of the surface layer to obtain a surface slurry. Coat the surface slurry onto the surface of the intermediate layer to form a surface layer with a thickness of 0.1 mm.

[0060] S4. Place a corrugated PE film on the upper surface of the surface layer, press it at room temperature using a roller with a diameter greater than 330mm and a pressure of 0.3MPa. After pressing, let it sit at room temperature for no less than 24 hours to cure. After curing, remove the PE film to obtain a multi-layer composite heat-resistant coating for the heat-resistant skirt.

[0061] Example 2

[0062] The heat-resistant skirt of this embodiment uses a multi-layer composite structure heat-resistant coating, which includes a base fabric layer (alkali-free glass fiber cloth EW50), a base layer, an intermediate layer and a surface layer stacked in sequence.

[0063] The base layer is prepared from the following components in parts by weight: 100 parts methyl vinyl silicone rubber (vinyl content 0.2%), 40 parts the first compound halogen-free flame retardant, 2 parts platinum catalyst, 7 parts polyimide resin, 25 parts fumed silica, and 10 parts chopped carbon fiber. The first compound halogen-free flame retardant is prepared from the following components in parts by weight: 30 parts ammonium polyphosphate, 7 parts antimony trioxide, and 4 parts nano-alumina. The base layer has a thickness of 0.25 mm.

[0064] The intermediate layer is prepared from the following components in parts by weight: 100 parts of methyl vinyl silicone rubber (vinyl content 0.15%), 80 parts of the second compounded halogen-free flame retardant, and 10 parts of polyimide resin. The second compounded halogen-free flame retardant is prepared from the following components in parts by weight: 25 parts of ammonium polyphosphate, 5 parts of antimony trioxide, and 3 parts of nano-alumina. The thickness of the intermediate layer is 0.4 mm.

[0065] The surface layer is prepared using the following components in parts by weight: 10 parts polyimide resin, 1 part zirconium oxide, and 4 parts alumina. The surface layer has a thickness of 0.15 mm. The upper surface of the surface layer is corrugated.

[0066] The preparation method of the multi-layer composite structure heat-resistant coating for the heat-resistant skirt in this embodiment is the same as that in Embodiment 1.

[0067] Example 3

[0068] The heat-resistant skirt of this embodiment uses a multi-layer composite structure heat-resistant coating, which includes a base fabric layer (alkali-free glass fiber cloth EW50), a base layer, an intermediate layer and a surface layer stacked in sequence.

[0069] The base layer is prepared from the following components in parts by weight: 100 parts methyl vinyl silicone rubber (vinyl content 0.3%), 50 parts the first compound halogen-free flame retardant, 3 parts platinum catalyst, 10 parts polyimide resin, 15 parts fumed silica, and 15 parts chopped carbon fiber. The first compound halogen-free flame retardant is prepared from the following components in parts by weight: 40 parts ammonium polyphosphate, 10 parts antimony trioxide, and 5 parts nano-alumina. The base layer has a thickness of 0.3 mm.

[0070] The intermediate layer is prepared from the following components in parts by weight: 100 parts of methyl vinyl silicone rubber (vinyl content 0.15%), 80 parts of the second compounded halogen-free flame retardant, and 10 parts of polyimide resin. The second compounded halogen-free flame retardant is prepared from the following components in parts by weight: 25 parts of ammonium polyphosphate, 5 parts of antimony trioxide, and 3 parts of nano-alumina. The thickness of the intermediate layer is 0.5 mm.

[0071] The surface layer is prepared using the following components in parts by weight: 10 parts polyimide resin, 1 part zirconium oxide, and 4 parts alumina. The surface layer has a thickness of 0.2 mm. The upper surface of the surface layer is corrugated.

[0072] The preparation method of the multi-layer composite structure heat-resistant coating for the heat-resistant skirt in this embodiment is the same as that in Embodiment 1.

[0073] Example 4

[0074] The heat-resistant skirt of this embodiment uses a multi-layer composite structure heat-resistant coating, which includes a base fabric layer (alkali-free glass fiber cloth EW50), a base layer, an intermediate layer and a surface layer stacked in sequence.

[0075] In this embodiment, the composition and proportions of the raw materials for the base layer and surface layer are the same as in Example 2, and the thicknesses of the base layer and surface layer are also the same as in Example 2. The difference lies in the raw materials for the intermediate layer. The raw materials for the intermediate layer include the following components in parts by weight: 100 parts of methyl vinyl silicone rubber (vinyl content 0.15%), 70 parts of the second compounded halogen-free flame retardant, and 15 parts of polyimide resin. The raw materials for the second compounded halogen-free flame retardant include the following components in parts by weight: 30 parts of ammonium polyphosphate, 10 parts of antimony trioxide, and 5 parts of nano-alumina. The thickness of the intermediate layer is 0.4 mm.

[0076] The preparation method of the multi-layer composite structure heat-resistant coating for the heat-resistant skirt in this embodiment is the same as that in Embodiment 1.

[0077] Example 5

[0078] The heat-resistant skirt of this embodiment uses a multi-layer composite structure heat-resistant coating, which includes a base fabric layer (alkali-free glass fiber cloth EW50), a base layer, an intermediate layer and a surface layer stacked in sequence.

[0079] In this embodiment, the composition and proportions of the raw materials for the base layer and surface layer are the same as in Example 2, and the thicknesses of the base layer and surface layer are also the same as in Example 2. The difference lies in the raw materials for the intermediate layer. The raw materials for the intermediate layer include the following components in parts by weight: 100 parts of methyl vinyl silicone rubber (vinyl content 0.15%), 90 parts of the second compounded halogen-free flame retardant, and 20 parts of polyimide resin. The raw materials for the second compounded halogen-free flame retardant include the following components in parts by weight: 40 parts of ammonium polyphosphate, 10 parts of antimony trioxide, and 3 parts of nano-alumina. The thickness of the intermediate layer is 0.4 mm.

[0080] The preparation method of the multi-layer composite structure heat-resistant coating for the heat-resistant skirt in this embodiment is the same as that in Embodiment 1.

[0081] Example 6

[0082] The heat-resistant skirt of this embodiment uses a multi-layer composite structure heat-resistant coating, which includes a base fabric layer (alkali-free glass fiber cloth EW50), a base layer, an intermediate layer and a surface layer stacked in sequence.

[0083] In this embodiment, the composition and proportions of the raw materials for the base layer and intermediate layer are the same as in Example 2, and the thicknesses of the base layer and intermediate layer are also the same as in Example 2. The difference lies in the raw materials for the surface layer. The raw materials for the surface layer include the following components in parts by weight: 15 parts polyimide resin, 2 parts zirconium oxide, and 7 parts alumina. The thickness of the surface layer is 0.15 mm. The upper surface of the surface layer is corrugated.

[0084] The preparation method of the multi-layer composite structure heat-resistant coating for the heat-resistant skirt in this embodiment is the same as that in Embodiment 1.

[0085] Example 7

[0086] The heat-resistant skirt of this embodiment uses a multi-layer composite structure heat-resistant coating, which includes a base fabric layer (alkali-free glass fiber cloth EW50), a base layer, an intermediate layer and a surface layer stacked in sequence.

[0087] In this embodiment, the composition and quantity of raw materials for each layer are the same as in Example 2, the difference being the thickness of each layer. In this embodiment, the base layer is 0.2 mm thick, the intermediate layer is 0.5 mm thick, and the surface layer is 0.1 mm thick.

[0088] The preparation method of the multi-layer composite structure heat-resistant coating for the heat-resistant skirt in this embodiment is the same as that in Embodiment 1.

[0089] Example 8

[0090] The heat-resistant skirt of this embodiment uses a multi-layer composite structure heat-resistant coating, which includes a base fabric layer (alkali-free glass fiber cloth EW50), a base layer, an intermediate layer and a surface layer stacked in sequence.

[0091] In this embodiment, the composition and quantity of raw materials for each layer are the same as in Example 2, the difference being the thickness of each layer. In this embodiment, the base layer is 0.3 mm thick, the intermediate layer is 0.3 mm thick, and the surface layer is 0.2 mm thick.

[0092] The preparation method of the multi-layer composite structure heat-resistant coating for the heat-resistant skirt in this embodiment is the same as that in Embodiment 1.

[0093] Example 9

[0094] The heat-resistant skirt of this embodiment uses a multi-layer composite structure heat-resistant coating, which includes a base fabric layer (alkali-free glass fiber cloth EW50), a base layer, an intermediate layer and a surface layer stacked in sequence.

[0095] In this embodiment, the composition and quantity of raw materials for each layer are the same as in Example 2, the difference being the thickness of each layer. In this embodiment, the base layer is 0.1 mm thick, the intermediate layer is 0.6 mm thick, and the surface layer is 0.25 mm thick.

[0096] The preparation method of the multi-layer composite structure heat-resistant coating for the heat-resistant skirt in this embodiment is the same as that in Embodiment 1.

[0097] Example 10

[0098] The heat-resistant skirt of this embodiment uses a multi-layer composite structure heat-resistant coating, which includes a base fabric layer (alkali-free glass fiber cloth EW50), a base layer, an intermediate layer and a surface layer stacked in sequence.

[0099] In this embodiment, the composition and quantity of raw materials for each layer are the same as in Example 2, the difference being the thickness of each layer. In this embodiment, the base layer is 0.4 mm thick, the intermediate layer is 0.2 mm thick, and the surface layer is 0.05 mm thick.

[0100] The preparation method of the multi-layer composite structure heat-resistant coating for the heat-resistant skirt in this embodiment is the same as that in Embodiment 1.

[0101] Example 11

[0102] The heat-resistant skirt of this embodiment uses a multi-layer composite structure heat-resistant coating, which includes a base fabric layer (alkali-free glass fiber cloth EW50), a base layer, an intermediate layer and a surface layer stacked in sequence.

[0103] In this embodiment, the composition and proportions of the raw materials for the intermediate layer and the surface layer are the same as in Example 2, and the thicknesses of the intermediate layer and the surface layer are also the same as in Example 2. The difference lies in the raw materials for the base layer. The raw materials for the base layer include the following components in parts by weight: 100 parts of methyl vinyl silicone rubber (vinyl content 0.2%), 20 parts of the first compound halogen-free flame retardant, 5 parts of platinum catalyst, 2 parts of polyimide resin, 25 parts of fumed silica, and 10 parts of chopped carbon fiber. The raw materials for the first compound halogen-free flame retardant include the following components in parts by weight: 30 parts of ammonium polyphosphate, 7 parts of antimony trioxide, and 4 parts of nano-alumina. The thickness of the base layer is 0.25 mm.

[0104] The preparation method of the multi-layer composite structure heat-resistant coating for the heat-resistant skirt in this embodiment is the same as that in Embodiment 1.

[0105] Example 12

[0106] The heat-resistant skirt of this embodiment uses a multi-layer composite structure heat-resistant coating, which includes a base fabric layer (alkali-free glass fiber cloth EW50), a base layer, an intermediate layer and a surface layer stacked in sequence.

[0107] In this embodiment, the composition and proportions of the raw materials for the intermediate layer and the surface layer are the same as in Example 2, and the thicknesses of the intermediate layer and the surface layer are also the same as in Example 2. The difference lies in the raw materials for the base layer. The raw materials for the base layer include the following components in parts by weight: 100 parts of methyl vinyl silicone rubber (vinyl content 0.2%), 55 parts of the first compound halogen-free flame retardant, 0.5 parts of platinum catalyst, 12 parts of polyimide resin, 25 parts of fumed silica, and 10 parts of chopped carbon fiber. The raw materials for the first compound halogen-free flame retardant include the following components in parts by weight: 30 parts of ammonium polyphosphate, 7 parts of antimony trioxide, and 4 parts of nano-alumina. The thickness of the base layer is 0.25 mm.

[0108] The preparation method of the multi-layer composite structure heat-resistant coating for the heat-resistant skirt in this embodiment is the same as that in Embodiment 1.

[0109] Example 13

[0110] The heat-resistant skirt of this embodiment uses a multi-layer composite structure heat-resistant coating, which includes a base fabric layer (alkali-free glass fiber cloth EW50), a base layer, an intermediate layer and a surface layer stacked in sequence.

[0111] In this embodiment, the composition and proportions of the raw materials for the intermediate layer and the surface layer are the same as in Example 2, and the thicknesses of the intermediate layer and the surface layer are also the same as in Example 2. The difference lies in the raw materials for the base layer. The raw materials for the base layer include the following components in parts by weight: 100 parts of methyl vinyl silicone rubber (vinyl content 0.2%), 30 parts of the first compound halogen-free flame retardant, 1 part of platinum catalyst, 5 parts of polyimide resin, 25 parts of fumed silica, and 10 parts of chopped carbon fiber. The raw materials for the first compound halogen-free flame retardant include the following components in parts by weight: 30 parts of ammonium polyphosphate, 7 parts of antimony trioxide, and 4 parts of nano-alumina. The thickness of the base layer is 0.25 mm.

[0112] The preparation method of the multi-layer composite structure heat-resistant coating for the heat-resistant skirt in this embodiment is the same as that in Embodiment 1.

[0113] Example 14

[0114] The heat-resistant skirt of this embodiment uses a multi-layer composite structure heat-resistant coating, which includes a base fabric layer (alkali-free glass fiber cloth EW50), a base layer, an intermediate layer and a surface layer stacked in sequence.

[0115] In this embodiment, the composition and proportions of the raw materials for the intermediate layer and the surface layer are the same as in Example 2, and the thicknesses of the intermediate layer and the surface layer are also the same as in Example 2. The difference lies in the raw materials for the base layer. The raw materials for the base layer include the following components in parts by weight: 100 parts of methyl vinyl silicone rubber (vinyl content 0.2%), 50 parts of the first compound halogen-free flame retardant, 3 parts of platinum catalyst, 10 parts of polyimide resin, 25 parts of fumed silica, and 10 parts of chopped carbon fiber. The raw materials for the first compound halogen-free flame retardant include the following components in parts by weight: 30 parts of ammonium polyphosphate, 7 parts of antimony trioxide, and 4 parts of nano-alumina. The thickness of the base layer is 0.25 mm.

[0116] The preparation method of the multi-layer composite structure heat-resistant coating for the heat-resistant skirt in this embodiment is the same as that in Embodiment 1.

[0117] Example 15

[0118] The heat-resistant skirt of this embodiment uses a multi-layer composite structure heat-resistant coating, which includes a base fabric layer (alkali-free glass fiber cloth EW50), a base layer, an intermediate layer and a surface layer stacked in sequence.

[0119] In this embodiment, the composition and proportions of the raw materials for the base layer and surface layer are the same as in Example 2, and the thicknesses of the base layer and surface layer are also the same as in Example 2. The difference lies in the raw materials for the intermediate layer. The raw materials for the intermediate layer include the following components in parts by weight: 95 parts of methyl vinyl silicone rubber (vinyl content 0.15%), 100 parts of the second compounded halogen-free flame retardant, and 30 parts of polyimide resin. The raw materials for the second compounded halogen-free flame retardant include the following components in parts by weight: 25 parts of ammonium polyphosphate, 5 parts of antimony trioxide, and 3 parts of nano-alumina. The thickness of the intermediate layer is 0.4 mm.

[0120] The preparation method of the multi-layer composite structure heat-resistant coating for the heat-resistant skirt in this embodiment is the same as that in Embodiment 1.

[0121] Example 16

[0122] The heat-resistant skirt of this embodiment uses a multi-layer composite structure heat-resistant coating, which includes a base fabric layer (alkali-free glass fiber cloth EW50), a base layer, an intermediate layer and a surface layer stacked in sequence.

[0123] In this embodiment, the composition and proportions of the raw materials for the base layer and surface layer are the same as in Example 2, and the thicknesses of the base layer and surface layer are also the same as in Example 2. The difference lies in the raw materials for the intermediate layer. The raw materials for the intermediate layer include the following components in parts by weight: 105 parts of methyl vinyl silicone rubber (vinyl content 0.15%), 65 parts of the second compounded halogen-free flame retardant, and 5 parts of polyimide resin. The raw materials for the second compounded halogen-free flame retardant include the following components in parts by weight: 25 parts of ammonium polyphosphate, 5 parts of antimony trioxide, and 3 parts of nano-alumina. The thickness of the intermediate layer is 0.4 mm.

[0124] The preparation method of the multi-layer composite structure heat-resistant coating for the heat-resistant skirt in this embodiment is the same as that in Embodiment 1.

[0125] Example 17

[0126] The heat-resistant skirt of this embodiment uses a multi-layer composite structure heat-resistant coating, which includes a base fabric layer (alkali-free glass fiber cloth EW50), a base layer, an intermediate layer and a surface layer stacked in sequence.

[0127] In this embodiment, the composition and proportions of the raw materials for the base layer and surface layer are the same as in Example 2, and the thicknesses of the base layer and surface layer are also the same as in Example 2. The difference lies in the raw materials for the intermediate layer. The raw materials for the intermediate layer include the following components in parts by weight: 95 parts of methyl vinyl silicone rubber (vinyl content 0.15%), 70 parts of the second compounded halogen-free flame retardant, and 20 parts of polyimide resin. The raw materials for the second compounded halogen-free flame retardant include the following components in parts by weight: 25 parts of ammonium polyphosphate, 5 parts of antimony trioxide, and 3 parts of nano-alumina. The thickness of the intermediate layer is 0.4 mm.

[0128] The preparation method of the multi-layer composite structure heat-resistant coating for the heat-resistant skirt in this embodiment is the same as that in Embodiment 1.

[0129] Example 18

[0130] The heat-resistant skirt of this embodiment uses a multi-layer composite structure heat-resistant coating, which includes a base fabric layer (alkali-free glass fiber cloth EW50), a base layer, an intermediate layer and a surface layer stacked in sequence.

[0131] In this embodiment, the composition and proportions of the raw materials for the base layer and surface layer are the same as in Example 2, and the thicknesses of the base layer and surface layer are also the same as in Example 2. The difference lies in the raw materials for the intermediate layer. The raw materials for the intermediate layer include the following components in parts by weight: 105 parts of methyl vinyl silicone rubber (vinyl content 0.15%), 90 parts of the second compounded halogen-free flame retardant, and 10 parts of polyimide resin. The raw materials for the second compounded halogen-free flame retardant include the following components in parts by weight: 25 parts of ammonium polyphosphate, 5 parts of antimony trioxide, and 3 parts of nano-alumina. The thickness of the intermediate layer is 0.4 mm.

[0132] The preparation method of the multi-layer composite structure heat-resistant coating for the heat-resistant skirt in this embodiment is the same as that in Embodiment 1.

[0133] Comparative Example 1

[0134] The heat-resistant skirt in this comparative example uses a multi-layer composite structure heat-resistant coating, which includes a base fabric layer (alkali-free glass fiber cloth EW50), a base layer, an intermediate layer and a surface layer stacked in sequence.

[0135] In this comparative example, the composition and proportions of the raw materials for the intermediate and surface layers are the same as in Example 2, and the thicknesses of the intermediate and surface layers are also the same as in Example 2. The difference lies in the raw materials for the base layer. The raw materials for the base layer include the following components in parts by weight: 100 parts of methyl vinyl silicone rubber (vinyl content 0.2%), 15 parts of the first compounded halogen-free flame retardant, 6 parts of platinum catalyst, 1 part of polyimide resin, 25 parts of fumed silica, and 10 parts of chopped carbon fiber. The raw materials for the first compounded halogen-free flame retardant include the following components in parts by weight: 30 parts of ammonium polyphosphate, 7 parts of antimony trioxide, and 4 parts of nano-alumina. The thickness of the base layer is 0.25 mm.

[0136] The preparation method of the multi-layer composite structure heat-resistant coating for the heat-resistant skirt in this comparative example is the same as that in Example 1.

[0137] Comparative Example 2

[0138] The heat-resistant skirt in this comparative example uses a multi-layer composite structure heat-resistant coating, which includes a base fabric layer (alkali-free glass fiber cloth EW50), a base layer, an intermediate layer and a surface layer stacked in sequence.

[0139] In this comparative example, the composition and proportions of the raw materials for the intermediate and surface layers are the same as in Example 2, and the thicknesses of the intermediate and surface layers are also the same as in Example 2. The difference lies in the raw materials for the base layer. The raw materials for the base layer include the following components in parts by weight: 100 parts of methyl vinyl silicone rubber (vinyl content 0.2%), 60 parts of the first compounded halogen-free flame retardant, 0.3 parts of platinum catalyst, 15 parts of polyimide resin, 25 parts of fumed silica, and 10 parts of chopped carbon fiber. The raw materials for the first compounded halogen-free flame retardant include the following components in parts by weight: 30 parts of ammonium polyphosphate, 7 parts of antimony trioxide, and 4 parts of nano-alumina. The thickness of the base layer is 0.25 mm.

[0140] The preparation method of the multi-layer composite structure heat-resistant coating for the heat-resistant skirt in this comparative example is the same as that in Example 1.

[0141] Comparative Example 3

[0142] The heat-resistant skirt in this comparative example uses a multi-layer composite structure heat-resistant coating, which includes a base fabric layer (alkali-free glass fiber cloth EW50), a base layer, an intermediate layer and a surface layer stacked in sequence.

[0143] In this comparative example, the composition and proportions of the raw materials for the base layer and surface layer are the same as in Example 2, and the thicknesses of the base layer and surface layer are also the same as in Example 2. The difference lies in the raw materials for the intermediate layer. The raw materials for the intermediate layer include the following components in parts by weight: 90 parts of methyl vinyl silicone rubber (vinyl content 0.15%), 110 parts of the second compounded halogen-free flame retardant, and 35 parts of polyimide resin. The raw materials for the second compounded halogen-free flame retardant include the following components in parts by weight: 25 parts of ammonium polyphosphate, 5 parts of antimony trioxide, and 3 parts of nano-alumina. The thickness of the intermediate layer is 0.4 mm.

[0144] The preparation method of the multi-layer composite structure heat-resistant coating for the heat-resistant skirt in this comparative example is the same as that in Example 1.

[0145] Comparative Example 4

[0146] The heat-resistant skirt in this comparative example uses a multi-layer composite structure heat-resistant coating, which includes a base fabric layer (alkali-free glass fiber cloth EW50), a base layer, an intermediate layer and a surface layer stacked in sequence.

[0147] In this comparative example, the composition and proportions of the raw materials for the base layer and surface layer are the same as in Example 2, and the thicknesses of the base layer and surface layer are also the same as in Example 2. The difference lies in the raw materials for the intermediate layer. The raw materials for the intermediate layer include the following components in parts by weight: 110 parts of methyl vinyl silicone rubber (vinyl content 0.15%), 60 parts of the second compounded halogen-free flame retardant, and 3 parts of polyimide resin. The raw materials for the second compounded halogen-free flame retardant include the following components in parts by weight: 25 parts of ammonium polyphosphate, 5 parts of antimony trioxide, and 3 parts of nano-alumina. The thickness of the intermediate layer is 0.4 mm.

[0148] The preparation method of the multi-layer composite structure heat-resistant coating for the heat-resistant skirt in this comparative example is the same as that in Example 1.

[0149] The flexibility, flame retardancy, thermal insulation performance, and mechanical properties of the multi-layer composite thermal insulation coating used in the above embodiments and comparative examples were measured, and the test results are shown in Table 1. The experimental conditions for the thermal insulation performance test were: 1) heat flow 700KW / m 2 Ablation time 40s, heat flow 200KW / m 2 The ablation time was 126 seconds, and the final back temperature of the heat-resistant coating was tested. 2) Heat flux was 300 KW / m. 2 The ablation time was 160 seconds, and the final temperature of the back heat protection coating was tested.

[0150] As can be seen from the data in Table 1, the multi-layer composite heat-resistant coatings for the heat-resistant skirts in each embodiment of this application all exhibit excellent flexibility, flame retardancy, thermal insulation performance, and mechanical properties. The difference between Comparative Examples 1 and 2 and Example 2 lies in the different raw materials used to prepare the base layer. In Comparative Examples 1 and 2, the proportions of each component in the base layer are unsuitable, resulting in poor overall performance of the heat-resistant coatings. In Comparative Examples 3 and 4, the proportions of each component in the intermediate layer are unsuitable, leading to poor overall performance of the heat-resistant coatings.

[0151] Compared with Examples 2 and 7-10, the difference lies in the thickness of each layer. Among them, the thickness of each layer in Examples 2, 7, and 8 is more suitable, and the overall performance of the heat-resistant coating is better than that in Examples 9 and 10.

[0152] Compared with Examples 2 and 11-14, the difference lies in the raw materials used to prepare the base layer. In particular, the proportions of raw materials used in Examples 2, 13, and 14 are more suitable, resulting in better overall performance of the heat-resistant coating than in Examples 11 and 12.

[0153] Compared with Examples 2 and 15-18, the difference lies in the raw materials used to prepare the intermediate layer. In particular, the proportions of raw materials used in Examples 2, 17, and 18 are more suitable, resulting in better overall performance of the heat-resistant coating than Examples 15 and 16.

[0154] Table 1

[0155]

[0156] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A multilayer composite structure heat-resistant coating for heat-resistant skirts, characterized in that: comprising a base cloth layer, a base layer, an intermediate layer and a surface layer arranged in sequence; the base layer is prepared from the following components in mass fraction: 100 parts of methyl vinyl silicone rubber, 20-55 parts of a first compounded halogen-free flame retardant, 0.5-5 parts of a vulcanizing agent, and 2-12 parts of a first heat-resistant modifier; the intermediate layer is prepared from the following components in mass fraction: 95-105 parts of methyl vinyl silicone rubber, 65-100 parts of a second compounded halogen-free flame retardant, and 5-30 parts of a second heat-resistant modifier; the surface layer is prepared from the following components in mass fraction: 5-20 parts of a third heat-resistant modifier, 0.5-3 parts of zirconium oxide, and 2-9 parts of aluminum oxide; the first compounded halogen-free flame retardant and the second compounded halogen-free flame retardant are prepared from the following components in mass fraction: 25-40 parts of an intumescent flame retardant, 5-10 parts of antimony trioxide, and 3-5 parts of nano-aluminum oxide; the intumescent flame retardant is one or a combination of polyphosphoric acid ammonium and pentaerythritol; the first heat-resistant modifier, the second heat-resistant modifier and the third heat-resistant modifier are polyimide resins. The base layer is prepared from the following components in mass fraction: 100 parts of methyl vinyl silicone rubber, 30-50 parts of a first compounded halogen-free flame retardant, 1-3 parts of a vulcanizing agent, and 5-10 parts of a first heat-resistant modifier; the intermediate layer is prepared from the following components in mass fraction: 95-105 parts of methyl vinyl silicone rubber, 70-90 parts of a second compounded halogen-free flame retardant, and 10-20 parts of a second heat-resistant modifier; the surface layer is prepared from the following components in mass fraction: 10-15 parts of a third heat-resistant modifier, 1-2 parts of zirconium oxide, and 4-7 parts of aluminum oxide. 3.The multilayer composite structure heat-resistant coating for heat-resistant skirts according to claim 2, characterized in that: the base layer is further prepared from the following components in mass fraction: 15-25 parts of fumed silica and 5-15 parts of carbon fiber short-cut fibers. 4.The multilayer composite structure heat-resistant coating for heat-resistant skirts according to claim 1, characterized in that: the vulcanizing agent is a platinum-gold catalyst. 5.The multilayer composite structure heat-resistant coating for heat-resistant skirts according to claim 1, characterized in that: the thickness of the base layer is 0.2-0.3 mm, the thickness of the intermediate layer is 0.3-0.5 mm, and the thickness of the surface layer is 0.1-0.2 mm. 6.The multilayer composite structure heat-resistant coating for heat-resistant skirts according to claim 1, characterized in that: the upper surface of the surface layer is corrugated or wrinkled. comprising the following steps:

2. The multi-layer composite thermal protection coating for thermal skirts according to claim 1, characterized in that: S1.mixing the base layer preparation materials to obtain a base layer slurry, placing the base layer slurry on the surface of the base cloth, and then high-temperature vulcanization to form the base layer; S2.mixing the intermediate layer preparation materials to obtain an intermediate layer slurry, placing the intermediate layer slurry on the surface of the base layer to form the intermediate layer; S3.mixing the surface layer preparation materials to obtain a surface layer slurry, placing the surface layer slurry on the surface of the intermediate layer to form the surface layer; ​ ​ ​ ​ ​ ​ ​ ​ 7. A method of producing a multilayer composite thermal protection coating for thermal skirts as claimed in any one of claims 1 to 6, characterized in that, ​ ​ ​ ​ S4. The obtained structure is pressed and then cured to obtain the multilayer composite structure heat-resistant coating for the heat-resistant skirt.

8. The preparation method of claim 7, wherein: Before pressing, a corrugated PE film is placed on the upper surface of the surface layer, and after pressing, a corrugated shape is formed on the upper surface of the surface layer; or before pressing, a pleated PE film is placed on the upper surface of the surface layer, and after pressing, a pleated shape is formed on the upper surface of the surface layer.

9. The preparation method of claim 7, wherein: In step S1, the temperature of high-temperature vulcanization is 150-180℃, and the time is 10 min.

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