Silicone rubber protective coating and preparation method and application thereof

Abstract

The application discloses a kind of silicon rubber protective coating and its preparation method and application, belong to the technical field of protective material.The preparation raw materials of the silicon rubber protective coating include 100 parts of room temperature vulcanization liquid silicone rubber, 10-20 parts of liquid methyl silicone resin, 10-20 parts of hydroxyl silicone oil, 10-20 parts of curing agent, 0.5-2 parts of catalyst, 30-60 parts of hollow microsphere and 5-10 parts of anticorrosive pigment by weight fraction;Wherein, the R / Si value of liquid methyl silicone resin is 0.95-1.10.The silicon rubber protective coating has good mechanical properties, heat insulation performance, corrosion resistance, and can only be in the form of single-layer coating to meet the effect of solid rocket engine heat and corrosion resistance demand at the same time.

Description

Technical Field

[0001] The present invention relates to the technical field of protective materials, and in particular to a silicone rubber protective coating and a preparation method and application thereof. Background Art

[0002] Solid rocket engines are a crucial component of solid-propellant launch vehicles. Rockets must adapt to complex storage environments and the high-temperature aerodynamic conditions of flight, necessitating surface protection through coating. Currently, the exterior of rocket engines utilizes a traditional multi-layer coating process, sequentially applying an anti-corrosion coating and then a thermal barrier coating to provide corrosion resistance and thermal insulation. However, this multi-layer coating process is inefficient, and the complex interfaces created by these layers can compromise the reliability of rocket engines.

[0003] In view of this, the present invention is proposed. Summary of the Invention

[0004] The purpose of the present invention is to provide a silicone rubber protective coating and its preparation method and application. The silicone rubber protective coating has good mechanical properties, thermal insulation properties, and corrosion resistance, and can achieve the effect of simultaneously meeting the heat protection and corrosion resistance requirements of solid rocket engines in the form of only a single layer of coating, thereby effectively improving or solving the above-mentioned technical problems.

[0005] This application can be implemented as follows:

[0006] In a first aspect, the present application provides a silicone rubber protective coating, wherein the raw materials for its preparation include, by weight, 100 parts of room temperature vulcanized liquid silicone rubber, 10-20 parts of liquid methyl silicone resin, 10-20 parts of hydroxy silicone oil, 10-20 parts of curing agent, 0.5-2 parts of catalyst, 30-60 parts of hollow microspheres, and 5-10 parts of anticorrosive pigment;

[0007] Among them, the R / Si value of liquid methyl silicone resin is 0.95-1.10.

[0008] In an optional embodiment, the room temperature vulcanizing liquid silicone rubber includes 107 silicone rubber.

[0009] In an optional embodiment, the room temperature vulcanized liquid silicone rubber includes at least one 107 silicone rubber having a viscosity of 1500 mPa·s to 5000 mPa·s.

[0010] In an optional embodiment, the hydroxyl value of the hydroxy silicone oil is 4%-12%;

[0011] and / or, the curing agent comprises at least one of methyltributylanoxime silane and vinyltributylanoxime silane;

[0012] and / or, the catalyst comprises at least one of dibutyltin dilaurate and stannous octoate;

[0013] and / or, the hollow microspheres include glass hollow microspheres;

[0014] And / or, the anti-corrosion pigment includes at least one of mica and aluminum tripolyphosphate.

[0015] In an optional embodiment, the prepared raw materials further include 5-10 parts of heat-resistant additives.

[0016] In an alternative embodiment, the refractory additive comprises ferric oxide.

[0017] In an optional embodiment, the preparation raw material further includes no more than 10 parts of white carbon black.

[0018] In an optional embodiment, the prepared raw material further includes no more than 200 parts of a diluent.

[0019] In a second aspect, the present application provides a method for preparing a silicone rubber protective coating as described in any one of the aforementioned embodiments, comprising the following steps: mixing raw materials in a proportion, and applying.

[0020] In an optional embodiment, room temperature vulcanized liquid silicone rubber, liquid methyl silicone resin, hydroxy silicone oil, hollow microspheres, heat-resistant additives, and rust-proof pigments are mixed to obtain a first mixture; the first mixture is mixed with a catalyst to obtain a second mixture; the second mixture is mixed with a curing agent to obtain a slurry; and the slurry is coated on a substrate and cured.

[0021] In an alternative embodiment, the base comprises an engine casing.

[0022] In an optional embodiment, the coating is applied by brushing or spraying;

[0023] And / or, curing is carried out at 15-60° C. for 24-72 hours.

[0024] In a third aspect, the present application provides an application of a silicone rubber protective coating according to any one of the aforementioned embodiments in corrosion and heat protection of a substrate.

[0025] In an alternative embodiment, the base comprises an engine casing.

[0026] In an alternative embodiment, the substrate is a rocket motor casing.

[0027] In a fourth aspect, the present application provides a rocket whose engine casing is coated with the silicone rubber protective coating of any of the aforementioned embodiments.

[0028] The beneficial effects of this application include:

[0029] This application adopts a co-curing system of liquid silicone rubber and liquid methyl silicone resin, and the R / Si value of methyl silicone resin is 0.95-1.10. Within this range, silicone resin usually needs to be cured by baking at high temperature (200-250°C). This application introduces hydroxy silicone oil as an activator. Under the action of a catalyst, the silicone resin is activated to achieve room temperature curing, and the paint film has good flexibility and good impact strength. In addition, combined with the composition and ratio of hollow microspheres and anti-corrosion pigments, the functions of corrosion resistance and heat protection are achieved at the same time. The corresponding silicone rubber protective coating has good mechanical properties, thermal insulation properties, and corrosion resistance, and can achieve the effect of simultaneously meeting the heat protection and corrosion protection requirements of solid rocket engines in the form of only a single layer of coating. DETAILED DESCRIPTION

[0030] To make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer are used. Where the manufacturer of the reagents or instruments is not specified, all are conventional products that can be purchased commercially.

[0031] The following is a detailed description of the silicone rubber protective coating provided in this application, its preparation method and application.

[0032] The present application proposes a silicone rubber protective coating, which has good mechanical properties, thermal insulation properties and anti-corrosion properties, and can achieve the effect of simultaneously meeting the heat protection and anti-corrosion requirements of solid rocket engines in the form of only a single layer of coating.

[0033] The raw materials for its preparation may include, by weight, 100 parts of room temperature vulcanized liquid silicone rubber, 10-20 parts of liquid methyl silicone resin, 10-20 parts of hydroxy silicone oil, 10-20 parts of curing agent, 0.5-2 parts of catalyst, 30-60 parts of hollow microspheres and 5-10 parts of anti-corrosion pigment.

[0034] The room temperature vulcanized liquid silicone rubber may include 107 silicone rubber, preferably 107 silicone rubber having a viscosity of 1500 mPa·s to 5000 mPa·s.

[0035] In some embodiments, the room temperature vulcanized liquid silicone rubber may be a single type of 107 silicone rubber having a viscosity of 1500 mPa·s to 5000 mPa·s. In other embodiments, the room temperature vulcanized liquid silicone rubber may be composed of two or more types of 107 silicone rubber having a viscosity of 1500 mPa·s to 5000 mPa·s. In other words, under such conditions, the room temperature vulcanized liquid silicone rubber is a mixture of different types of 107 silicone rubber.

[0036] It should be noted that the use of 107 silicone rubber with a viscosity of 1500 mPa·s to 5000 mPa·s is conducive to the dispersion of fillers and the viscosity control of the coating base. If 107 silicone rubber with a viscosity higher than 5000 mPa·s is used, it is easy to cause the functional filler filling amount to be too low due to too high viscosity, resulting in poor process performance; if other silicone rubber (such as 108 silicone rubber) with a viscosity lower than 1500 mPa·s is used, it is easy to cause the elongation to be low due to too high crosslinking degree, or the coating strength to be low due to insufficient cohesion.

[0037] In the present application, the R / Si value of the liquid methyl silicone resin is 0.95-1.10, such as 0.95, 1.00, 1.05 or 1.10, etc.

[0038] The amount of the liquid methyl silicone resin can exemplarily be 10 parts, 11 parts, 12 parts, 13 parts, 14 parts, 15 parts, 16 parts, 17 parts, 18 parts, 19 parts or 20 parts, etc., or any other value within the range of 10-20 parts.

[0039] It should be noted that the liquid methyl silicone resin with an R / Si value of 0.95-1.10 is specifically used in the present application, because it not only ensures the room temperature curing of the coating through the activation of a certain amount of hydroxyl silicone oil, but also ensures the appropriate elongation and hardness to meet the needs of the engine. If the R / Si value of the liquid methyl silicone resin is lower than 0.95, it is not conducive to the temperature resistance, and the hardness of the cured coating is too high and the elongation is insufficient; if the R / Si value is higher than 1.10, it is not conducive to the dispersion of the silicone resin in the 107 glue and the room temperature curing, and the hardness of the coating is poor. In addition, if the amount of the liquid methyl silicone resin is less than 10 parts, it is not conducive to the improvement of the coating strength and the temperature resistance; if the amount of the liquid methyl silicone resin is greater than 20 parts, the coating elongation is too low, the hardness is too high, and the coating is brittle.

[0040] In the present application, the hydroxyl value of the hydroxyl silicone oil can be 4%-12%, such as 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11% or 12%, etc., or any other value within the range of 4%-12%.

[0041] The amount of the hydroxyl silicone oil can exemplarily be 10 parts, 11 parts, 12 parts, 13 parts, 14 parts, 15 parts, 16 parts, 17 parts, 18 parts, 19 parts or 20 parts, etc., or any other value within the range of 10-20 parts.

[0042] It should be noted that the hydroxyl silicone oil with a hydroxyl value of 4%-12% is specifically used in the present application because of the following reasons: the moderate molecular weight can effectively react with the silicon hydroxyl groups of the silicone resin with low activity, and through the activation reaction, the silicone resin can enter the curing crosslinking network. If the hydroxyl value of the hydroxyl silicone oil is less than 4%, the chain segment is too long, which is not conducive to the activation of the hydroxyl group due to steric hindrance; and if the hydroxyl value is higher than 12%, it is not conducive to the establishment of the three-dimensional network. In addition, if the amount of the hydroxyl silicone oil is less than 10 parts, the amount of the activator is not enough, which leads to too low strength; and if the amount of the hydroxyl silicone oil is greater than 20 parts, the crosslinking degree is too high, the elongation of the coating is reduced, the hardness is increased, and the coating is too brittle to resist stress impact.

[0043] In the present application, the curing agent may, for example, include at least one of methyl tributyl ketoxime silane and vinyl tributyl ketoxime silane. By using the above ketoxime silane substance as the curing agent, not only high reactivity is achieved, but also good adhesion is achieved.

[0044] The amount of the curing agent may, for example, be 10 parts, 11 parts, 12 parts, 13 parts, 14 parts, 15 parts, 16 parts, 17 parts, 18 parts, 19 parts, or 20 parts, etc., or any other value within the range of 10-20 parts. Within the above amount range, the slurry can be effectively cured.

[0045] In the present application, the catalyst may, for example, include at least one of dibutyltin dilaurate and stannous octoate.

[0046] The amount of the catalyst may, for example, be 0.5 parts, 0.8 parts, 1 part, 1.2 parts, 1.5 parts, 1.8 parts, or 2 parts, etc., or any other value within the range of 0.5-2 parts. Within the above amount range, a better catalytic effect can be achieved.

[0047] In the present application, the hollow microspheres may, for example, include glass hollow microspheres.

[0048] The amount of the hollow microspheres may, for example, be 30 parts, 35 parts, 40 parts, 45 parts, 50 parts, 55 parts, or 60 parts, etc., or any other value within the range of 30-60 parts.

[0049] By adding the above amount of the hollow microspheres, the thermal conductivity of the coating can be reduced, and the heat protection function under medium heat flux can be achieved.

[0050] In the present application, the anticorrosive pigment may, for example, include at least one of mica and aluminum tripolyphosphate, and preferably both mica and aluminum tripolyphosphate are included to simultaneously contain physical anticorrosive pigment and chemical anticorrosive pigment. In addition, the above anticorrosive pigment is in the form of a sheet, which is more conducive to the anticorrosive function.

[0051] The amount of anticorrosive pigment used can be illustratively 5 parts, 5.5 parts, 6 parts, 6.5 parts, 7 parts, 7.5 parts, 8 parts, 8.5 parts, 9 parts, 9.5 parts or 10 parts, etc., or any other value within the range of 5-10 parts.

[0052] By adding the above amount of anti-corrosion pigment, the anti-corrosion function during storage can be effectively achieved.

[0053] Continuing from the above, the present application introduces a specific liquid methyl silicone resin component into the rubber curing system and adds a specific hydroxyl silicone oil to activate the residual silanol groups in the silicone resin that require high temperature (greater than 150°C) to be reactive. The activated silanol groups in the silicone resin have strong reactivity at room temperature and can react and cross-link with the curing agent, thereby enabling the silicone resin to participate in the construction of the entire silicone rubber network, increasing the interaction force between silicone rubber molecules, and achieving reinforcement of the silicone rubber; in addition, the silicone resin molecules participating in the network construction limit the flipping of the flexible chain segments of the silicone rubber, increase the surface energy of the silicone rubber, significantly improve the adhesion and repairability of the silicone rubber coating, and significantly improve the heat resistance of the silicone rubber coating (for example, it can be increased from 350°C to above 400°C).

[0054] Furthermore, the addition of hollow microspheres reduces the coating's thermal conductivity, achieving heat protection at moderate heat flux densities. The addition of flaky physical and chemical anticorrosive pigments enhances corrosion protection during storage. The optimal ratio of hollow microspheres to anticorrosive pigments achieves both heat and corrosion protection.

[0055] In some embodiments, the raw materials may further include 5-10 parts (e.g., 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, or 10 parts) of a heat-resistant additive. For example, the heat-resistant additive may include ferric oxide.

[0056] In some embodiments, the above-mentioned preparation raw materials may also include no more than 10 parts (such as 10 parts, 9 parts, 8 parts, 7 parts, 6 parts, 5 parts, 4 parts, 3 parts, 2 parts or 1 part, etc.) of white carbon black to reinforce and improve the mechanical properties of the coating.

[0057] In some embodiments, the raw materials may further include no more than 200 parts (e.g., 200 parts, 150 parts, 100 parts, 80 parts, 50 parts, or 20 parts, etc.) of a diluent. For example, the diluent may include 120# solvent gasoline or toluene.

[0058] Continuing from the above, compared with the traditional silicone rubber heat-resistant coating system, this application adopts a silicone rubber and silicone resin blend system formula, uses hollow microspheres and anti-corrosion pigments, and while ensuring the anti-thermoelectric performance, the comprehensive performance is significantly improved, especially the elongation and adhesion performance, and can also achieve anti-corrosion performance at the same time.

[0059] In some embodiments, the silicone rubber coating provided in the present application has a tensile strength of up to 3 MPa, an elongation at break of more than 40%, a bonding strength between the substrate (steel material) and the coating of up to 3 MPa, a thermal conductivity of up to 0.18 W / (m·K), salt spray resistance of up to 1000 h, and a thermal decomposition temperature greater than 400°C.

[0060] Accordingly, the present application provides a method for preparing the above-mentioned silicone rubber protective coating, comprising the following steps: mixing raw materials according to a ratio, and applying.

[0061] In some embodiments, for example, the following steps may be performed:

[0062] Room temperature vulcanized liquid silicone rubber, liquid methyl silicone resin, hydroxy silicone oil, hollow microspheres, heat-resistant additives, and rust-proof pigments are mixed to obtain a first mixture. In a specific operation, the room temperature vulcanized liquid silicone rubber, liquid methyl silicone resin, hydroxy silicone oil, hollow microspheres, heat-resistant additives, and rust-proof pigments can be dispersed in a high-speed disperser and then ground using a three-roll mill to a fineness of no more than 50 μm to obtain the first mixture.

[0063] Subsequently, the first mixed material is mixed with a catalyst to obtain a second mixed material; the second mixed material is then mixed with a curing agent to obtain a slurry; the slurry is coated on a substrate and cured.

[0064] When the raw materials also contain white carbon black and a diluent, the white carbon black is added when preparing the first mixed material, and the diluent is added when coating (ie, the slurry is diluted before coating).

[0065] For reference, the substrate may include a motor casing, such as a steel motor casing. For example, the substrate may be a steel solid rocket motor casing.

[0066] The coating may be applied by brushing or spraying, for example but not by way of limitation.

[0067] Curing can be carried out at 15-60°C (such as 15°C, 2°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C or 60°C, etc.) for 24-72h (such as 24h, 30h, 36h, 42h, 48h, 54h or 60h, etc.).

[0068] As mentioned above, the preparation method provided in this application is simple to operate and the process is easy to control.

[0069] In addition, the present application also provides an application of the above-mentioned silicone rubber protective coating in substrate corrosion and heat protection.

[0070] Similarly, the substrate may include a motor casing, such as a steel motor casing. For example, the substrate may be a steel solid rocket motor casing.

[0071] In addition, the present application also provides a rocket whose engine casing is coated with the above-mentioned silicone rubber protective coating, and the rocket has excellent heat resistance and corrosion resistance.

[0072] The features and properties of the present invention are further described in detail below with reference to the examples. The same materials in the following examples were purchased from the same merchant.

[0073] Example 1

[0074] This embodiment provides a silicone rubber protective coating, which is prepared by the following steps:

[0075] S1: Prepare ingredients.

[0076] Room temperature vulcanized liquid silicone rubber: 107 silicone rubber (1500 mPa·s), 100 parts, purchased from Hubei Xinsihai Chemical Co., Ltd.

[0077] Liquid methyl silicone resin: R / Si value 0.95, 20 parts, purchased from Shanghai Resin Factory Co., Ltd.;

[0078] Hydroxyl silicone oil: hydroxyl value 12%, 20 parts, purchased from Hubei Xinsihai Chemical Co., Ltd.;

[0079] Curing agent: methyl tributylidene oxime silane, 20 parts, purchased from Hubei New Blue Sky New Materials Co., Ltd.

[0080] Catalyst: 0.2 parts of stannous octoate, purchased from Henan Fanrui Composite Materials Research Institute.

[0081] Hollow microspheres: Glass hollow microspheres, 60 parts, purchased from Shanghai Rhine Chemical Co., Ltd.

[0082] Anticorrosive pigment: mica, 2 parts, purchased from Lingshou County Huajing Mica Co., Ltd.; aluminum tripolyphosphate 3 parts, purchased from Shanghai Lishen Chemicals Co., Ltd.;

[0083] Heat-resistant additive: ferric oxide, 5 parts, purchased from Shijiazhuang Daheng Mineral Products Processing Co., Ltd.

[0084] S2: preparing coating slurry.

[0085] The room temperature vulcanized liquid silicone rubber, liquid methyl silicone resin, hydroxy silicone oil, hollow microspheres, heat-resistant additives, and anti-corrosion pigments in S1 are dispersed in a high-speed disperser and then ground using a three-roll mill to a fineness of no more than 50 μm to obtain a first mixture. The first mixture is mixed with a catalyst to obtain a second mixture. The second mixture is mixed with a curing agent to obtain a coating slurry.

[0086] S3: coating.

[0087] After the outer wall of the steel engine casing to be treated is solvent degreased, cleaned and dried, the slurry obtained in S2 is diluted with 100 parts of diluent (120# solvent gasoline), and then the diluted coating slurry is sprayed onto the dried steel engine casing at room temperature with a spraying thickness of about 2.0 mm. It is placed at 25°C for curing for 24 hours to obtain an engine casing with a dual-function silicone rubber protective coating.

[0088] Example 2

[0089] This embodiment provides a silicone rubber protective coating, which is prepared by the following steps:

[0090] S1: Prepare ingredients.

[0091] Room temperature vulcanized liquid silicone rubber: 107 silicone rubber (1500 mPa·s), 20 parts; 107 silicone rubber (5000 mPa·s), 80 parts, purchased from Shanghai Resin Factory Co., Ltd.

[0092] Liquid methyl silicone resin: R / Si value is 0.95, 10 parts; hydroxy silicone oil: hydroxyl value is 4%, 10 parts, purchased from Hubei Xinsihai Chemical Co., Ltd.

[0093] Curing agent: 5 parts of methyl tributylanoxime silane and 5 parts of vinyl tributylanoxime silane, purchased from Hubei New Blue Sky New Materials Co., Ltd.

[0094] Catalyst: dibutyltin dilaurate, 1 part, purchased from Guangdong Guanghua Technology Co., Ltd.

[0095] Hollow microspheres: glass hollow microspheres, 30 parts;

[0096] Anticorrosive pigment: mica, 5 parts; aluminum tripolyphosphate 5 parts;

[0097] Heat-resistant additive: ferric oxide, 10 parts;

[0098] White carbon black: 5 parts, purchased from Tonghua Shuanglong Silicon Material Technology Co., Ltd.

[0099] S2: preparing coating slurry.

[0100] The room temperature vulcanized liquid silicone rubber, liquid methyl silicone resin, hydroxy silicone oil, hollow microspheres, heat-resistant additives, anticorrosive pigment, and white carbon black in S1 are dispersed in a high-speed disperser and then ground using a three-roll mill to a fineness of no more than 50 μm to obtain a first mixture. The first mixture is mixed with a catalyst to obtain a second mixture. The second mixture is mixed with a curing agent to obtain a coating slurry.

[0101] S3: coating.

[0102] After the outer wall of the steel engine casing to be treated is solvent degreased, cleaned and dried, the slurry obtained in S2 is brushed onto the dried steel engine casing with a spraying thickness of about 4.0 mm. It is placed at 15°C and cured for 72 hours to obtain an engine casing with a dual-functional silicone rubber protective coating.

[0103] Example 3

[0104] This embodiment provides a silicone rubber protective coating, which is prepared by the following steps:

[0105] S1: Prepare ingredients.

[0106] Room temperature vulcanized liquid silicone rubber: 107 silicone rubber (5000 mPa·s), 100 parts;

[0107] Liquid methyl silicone resin: R / Si value 1.0, 15 parts, purchased from Shandong Dayi Chemical Co., Ltd.;

[0108] Hydroxyl silicone oil: hydroxyl value 4%, 5 parts; hydroxyl value 12%, 5 parts;

[0109] Curing agent: vinyl trisbutyl ketoxime silane, 15 parts;

[0110] Catalyst: dibutyltin dilaurate, 0.8 parts.

[0111] Hollow microspheres: glass hollow microspheres, 50 parts;

[0112] Anticorrosive pigment: mica, 2 parts; aluminum tripolyphosphate 8 parts;

[0113] Heat-resistant additive: ferric oxide, 8 parts.

[0114] White carbon black: 10 parts.

[0115] S2: preparing coating slurry.

[0116] The room temperature vulcanized liquid silicone rubber, liquid methyl silicone resin, hydroxy silicone oil, hollow microspheres, heat-resistant additives, anticorrosive pigment, and white carbon black in S1 are dispersed in a high-speed disperser and then ground using a three-roll mill to a fineness of no more than 50 μm to obtain a first mixture. The first mixture is mixed with a catalyst to obtain a second mixture. The second mixture is mixed with a curing agent to obtain a coating slurry.

[0117] S3: coating.

[0118] After the outer wall of the steel engine casing to be treated is solvent degreased, cleaned and dried, the slurry obtained in S2 is diluted with 200 parts of diluent (120# solvent gasoline), and then the diluted coating slurry is sprayed onto the dried steel engine casing at room temperature with a spraying thickness of about 4.0 mm. It is placed at 60°C for curing for 24 hours to obtain an engine casing with a dual-function silicone rubber protective coating.

[0119] Example 4

[0120] This embodiment provides a silicone rubber protective coating, which is prepared by the following steps:

[0121] S1: Prepare ingredients.

[0122] Room temperature vulcanized liquid silicone rubber: 107 silicone rubber (2000 mPa·s), 100 parts, purchased from Hubei Xinsihai Chemical Co., Ltd.

[0123] Liquid methyl silicone resin: R / Si value 1.10, 20 parts, purchased from Hubei Xinsihai Chemical Co., Ltd.

[0124] Hydroxyl silicone oil: hydroxyl value 12%, 10 parts;

[0125] Curing agent: 12 parts of methyl tributylanoxime silane; 3 parts of vinyl tributylanoxime silane;

[0126] Catalyst: dibutyltin dilaurate, 0.5 parts.

[0127] Hollow microspheres: glass hollow microspheres, 55 parts;

[0128] Anticorrosive pigment: mica, 4 parts; aluminum tripolyphosphate 6 parts;

[0129] Heat-resistant additive: ferric oxide, 5 parts.

[0130] S2: preparing coating slurry.

[0131] The room temperature vulcanized liquid silicone rubber, liquid methyl silicone resin, hydroxy silicone oil, hollow microspheres, heat-resistant additives, and anti-corrosion pigments in S1 are dispersed in a high-speed disperser and then ground using a three-roll mill to a fineness of no more than 50 μm to obtain a first mixture. The first mixture is mixed with a catalyst to obtain a second mixture. The second mixture is mixed with a curing agent to obtain a coating slurry.

[0132] S3: coating.

[0133] After the outer wall of the steel engine casing to be treated is solvent degreased, cleaned and dried, the slurry obtained in S2 is diluted with 200 parts of diluent (toluene), and then the diluted coating slurry is sprayed onto the dried steel engine casing at room temperature with a spraying thickness of about 3.0 mm. It is placed at 50°C for curing for 48 hours to obtain an engine casing with a dual-function silicone rubber protective coating.

[0134] Example 5

[0135] This embodiment provides a silicone rubber protective coating, which is prepared by the following steps:

[0136] S1: Prepare ingredients.

[0137] Room temperature vulcanized liquid silicone rubber: 107 silicone rubber (2000 mPa·s), 60 parts, purchased from Hubei Xinsihai Chemical Co., Ltd.; 107 silicone rubber (3000 mPa·s), 40 parts, purchased from Shanghai Resin Factory Co., Ltd.

[0138] Liquid methyl silicone resin: R / Si value is 1.10, 15 parts;

[0139] Hydroxyl silicone oil: hydroxyl value 12%, 15 parts;

[0140] Curing agent: methyl tributylidene oxime silane, 12 parts;

[0141] Catalyst: stannous octoate, 0.5 parts.

[0142] Hollow microspheres: glass hollow microspheres, 60 parts;

[0143] Anticorrosive pigment: mica, 4 parts; aluminum tripolyphosphate 6 parts;

[0144] Heat-resistant additive: ferric oxide, 5 parts.

[0145] S2: preparing coating slurry.

[0146] The room temperature vulcanized liquid silicone rubber, liquid methyl silicone resin, hydroxy silicone oil, hollow microspheres, heat-resistant additives, and anti-corrosion pigments in S1 are dispersed in a high-speed disperser and then ground using a three-roll mill to a fineness of no more than 50 μm to obtain a first mixture. The first mixture is mixed with a catalyst to obtain a second mixture. The second mixture is mixed with a curing agent to obtain a coating slurry.

[0147] S3: coating.

[0148] The outer wall of the steel engine shell to be treated is subjected to solvent degreasing, cleaning and drying, and then the coating slurry is sprayed to the dried steel engine shell at room temperature, the spraying thickness is about 3.0 mm, and the engine shell with the bifunctional silicone rubber protective coating is obtained by curing at 45℃ for 24 h.

[0149] Comparative Example 1

[0150] The difference between this comparative example and Example 1 is that the R / Si value of the liquid methyl silicone resin is 0.90.

[0151] Comparative Example 2

[0152] The difference between this comparative example and Example 1 is that the R / Si value of the liquid methyl silicone resin is 1.15.

[0153] Comparative Example 3

[0154] The difference between this comparative example and Example 1 is that the amount of the liquid methyl silicone resin is 5 parts.

[0155] Comparative Example 4

[0156] The difference between this comparative example and Example 1 is that the amount of the liquid methyl silicone resin is 25 parts.

[0157] Comparative Example 5

[0158] The difference between this comparative example and Example 1 is that the viscosity of the room temperature vulcanizing liquid silicone rubber is 5500 mPa·s of 107 silicone rubber.

[0159] Comparative Example 6

[0160] The difference between this comparative example and Example 1 is that the hydroxyl value of the hydroxyl silicone oil is 3%.

[0161] Comparative Example 7

[0162] The difference between this comparative example and Example 1 is that the hydroxyl value of the hydroxyl silicone oil is 15%.

[0163] Comparative Example 8

[0164] The difference between this comparative example and Example 1 is that the amount of the hydroxyl silicone oil is 5 parts.

[0165] Comparative Example 9

[0166] The difference between this comparative example and Example 1 is that the amount of the hydroxyl silicone oil is 25 parts.

[0167] Comparative Example 10

[0168] The difference between this comparative example and Example 1 is that the amount of the curing agent is 5 parts.

[0169] Comparative Example 11

[0170] The difference between the present comparative example and Example 1 is that the amount of the curing agent is 25 parts.

[0171] Comparative Example 12

[0172] The difference between the present comparative example and Example 1 is that the amount of the catalyst is 2.5 parts.

[0173] Comparative Example 13

[0174] The difference between the present comparative example and Example 1 is that the amount of the hollow microspheres is 25 parts.

[0175] Comparative Example 14

[0176] The difference between the present comparative example and Example 1 is that the amount of the hollow microspheres is 65 parts.

[0177] Comparative Example 15

[0178] The difference between the present comparative example and Example 1 is that the amount of the corrosion-resistant pigment is 2 parts.

[0179] Comparative Example 16

[0180] The difference between the present comparative example and Example 1 is that the amount of the corrosion-resistant pigment is 12 parts.

[0181] Comparative Example 17

[0182] The difference between the present comparative example and Example 1 is that the hollow microspheres are not contained in the raw materials.

[0183] Comparative Example 18

[0184] The difference between the present comparative example and Example 1 is that the corrosion-resistant pigment is not contained in the raw materials.

[0185] Test Example

[0186] The dual-functional silicone rubber protective coatings prepared in Examples 1-5 and Comparative Examples 1-18 are subjected to performance tests in the following manner, and the results are shown in Table 1.

[0187] Among them, the dual-functional coating test pieces are prepared according to QJ917A “Method for Determining the Density of Composite Solid Propellant and Lining and Insulation Materials”, Q / G 197 “Method for Determining the Tensile Strength and Elongation at Break of Solid Rocket Engine Combustion Chamber Insulation and Lining Materials”, and the density and mechanical properties of the test pieces are tested respectively.

[0188] The joint adhesive test pieces of steel pieces / coatings are prepared according to QJ 2038.1 “Method for Testing the Interfacial Adhesion Strength of Solid Rocket Engine Combustion Chambers by Pulling Apart”, and the adhesion strength of the test pieces is tested.

[0189] According to Q / G 261 “Test method for thermal diffusivity, specific heat capacity and thermal conductivity of solid materials - Laser pulse method”, a thermal protection coating specimen was prepared and the thermal conductivity of the specimen was tested.

[0190] Prepare samples according to GB / T 1771 "Paints and varnishes - Determination of resistance to neutral salt spray" and test the coating for blistering, peeling and rusting after the preset salt spray test time.

[0191] Table 1 Test results

[0192]

[0193]

[0194]

[0195]

[0196] As can be seen from Table 1, the silicone rubber protective coating provided in this application has good tensile strength, elongation at break, bonding strength, thermal conductivity and salt spray resistance.

[0197] In summary, the silicone rubber protective coating provided in this application has good mechanical properties, thermal insulation properties, and anti-corrosion properties, and can achieve the effect of simultaneously meeting the heat protection and anti-corrosion requirements of solid rocket engines in the form of only a single layer of coating.

[0198] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A silicone rubber protective coating, characterized in that: The raw materials for preparing the silicone rubber protective coating include, by weight, 100 parts of room temperature vulcanized liquid silicone rubber, 10-20 parts of liquid methyl silicone resin, 10-20 parts of hydroxy silicone oil, 10-20 parts of curing agent, 0.5-2 parts of catalyst, 30-60 parts of hollow microspheres, 5-10 parts of anticorrosive pigment, 5-10 parts of heat-resistant additive, no more than 10 parts of white carbon black, and no more than 200 parts of diluent; The R / Si value of the liquid methyl silicone resin is 0.95-1.10; the room temperature vulcanized liquid silicone rubber includes at least one 107 silicone rubber with a viscosity of 1500mPa·s to 5000mPa·s; the hydroxyl value of the hydroxy silicone oil is 4%-12%; the curing agent includes at least one of methyl tributylidene oxime silane and vinyl tributylidene oxime silane; the hollow microspheres include glass hollow microspheres; the anti-corrosion pigment includes at least one of mica and aluminum tripolyphosphate; and the heat-resistant additive includes ferric oxide.

2. The silicone rubber protective coating according to claim 1, characterized in that: The catalyst includes at least one of dibutyltin dilaurate and stannous octoate.

3. A method for preparing a silicone rubber protective coating according to any one of claims 1 to 2, characterized in that: The following steps are involved: The prepared raw materials are mixed according to the proportions and coated.

4. The preparation method according to claim 3, characterized in that Room temperature vulcanized liquid silicone rubber, liquid methyl silicone resin, hydroxy silicone oil, hollow microspheres, heat-resistant additives and rust-proof pigments are mixed to obtain a first mixture; the first mixture is mixed with a catalyst to obtain a second mixture; the second mixture is mixed with a curing agent to obtain a slurry; the slurry is coated on a substrate and cured.

5. The preparation method according to claim 4, characterized in that The base includes an engine housing.

6. The preparation method according to claim 3, characterized in that The coating is applied by brush or spray; And / or, curing is carried out at 15-60° C. for 24-72 hours.

7. Use of the silicone rubber protective coating according to any one of claims 1 to 2 in substrate corrosion and heat protection.

8. The use according to claim 7, characterized in that The base includes an engine housing.

9. The use according to claim 8, characterized in that The matrix is ​​a rocket engine casing.

10. A rocket, characterized in that: The engine casing of the rocket is coated with the silicone rubber protective coating according to any one of claims 1-2.

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