Silicone rubber thermal protection material containing modified silica powder and preparation method thereof
By using modified silicon micropowder in silicone rubber thermal protection materials, the problem of poor mechanical properties and easy cracking at high temperatures is solved, and excellent ablation resistance and mechanical properties are improved.
Patent Information
- Application Number
- CN202411992266.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-31
- Publication Date
- 2025-05-09
AI Technical Summary
Existing silicone rubber thermal protection materials have problems such as poor mechanical properties and prone to cracking and falling off at high temperatures, which are difficult to meet the high-temperature anti-shrink performance requirements in space vehicles and other fields.
Modified silicon micropowder is used to replace conventional gas-phase white carbon black reinforcement agent, and spherical modified silicon micropowder is formed by combining the octa (phenyldimethoxysilyl) cage-shaped silsesquioxane modifier with the silicon micropowder to form a spherical modified silicon micropowder, which is used to prepare silicon rubber thermal protection materials.
Modified silicon micropowder has excellent dispersion, fluidity and low thermal expansion coefficient in silicon rubber systems, which improves the mechanical properties and ablation resistance of the material and avoids cracking and falling off at high temperatures.
Smart Images
Figure CN119955309A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of surface thermal protection materials, and in particular to a silicone rubber thermal protection material containing modified silicon micropowder and a preparation method thereof. Background Art
[0002] When a spacecraft flies at hypersonic speed, it interacts with the atmosphere to produce a violent aerodynamic heating flow field, resulting in a high temperature of nearly 2500℃. In order to protect the spacecraft from high temperature damage during operation, thermal protection materials are needed. Silicone rubber is a linear high molecular polymer composed of alternating silicon and oxygen. Its side chain can be connected to heat-resistant functional groups such as vinyl and phenyl. It has excellent thermal stability and ablation resistance. It is currently an ideal material for thermal protection materials in the fields of rocket engines and spacecraft return capsules. However, silicone rubber has poor mechanical properties and is prone to cracking and falling off at high temperatures, which has a significant impact on the anti-erosion performance of silicone rubber thermal protection materials and needs to be reinforced by functional fillers. Silica powder has excellent high thermal stability, mechanical properties and low expansion coefficient, and also has low-cost characteristics. It is widely used as a functional filler in the preparation of polymer composite materials and is used in epoxy molding compounds, copper clad laminates, rubber products and coatings. In the prior art, fumed silica is generally used as a reinforcing material to improve the poor mechanical properties of silicone rubber thermal protection materials and the problem of easy cracking and falling off at high temperatures. However, its performance still cannot meet the relevant application requirements.
[0003] Therefore, it is necessary to provide a silicone rubber thermal protection material containing modified silicon micropowder to improve the anti-scouring performance of the thermal protection material. Summary of the invention
[0004] Based on the above, the object of the present invention is to provide a silicone rubber thermal protection material containing modified silicon powder, which has excellent mechanical properties and anti-ablation properties.
[0005] To achieve the above object, the present invention adopts the following technical solutions:
[0006] A silicone rubber thermal protection material containing modified silicon micropowder, comprising the following raw material components in parts by mass:
[0007]
[0008] The modified silicon micropowder includes silicon micropowder modified with octa(phenyldimethoxysilyl) cage-shaped silsesquioxane.
[0009] As a preferred embodiment of a silicone rubber thermal protection material containing modified silicon micropowder, the structural formula of the octa(phenyldimethoxysilyl) cage-shaped silsesquioxane is:
[0010]
[0011] As a preferred solution of silicone rubber thermal protection material containing modified silicon micropowder, the preparation method of the octa(phenyldimethoxysilyl) cage-type silsesquioxane is as follows: octa(phenyldimethoxysilyl) cage-type silsesquioxane (cas: 69667-29-4) and phenyldimethoxychlorosilane are added to a dissolving solvent in a molar ratio of 1:(8-10), and the reaction time is 12-72 hours at a temperature of -10°C to 100°C;
[0012] The dissolution aid solvent includes one or more of toluene, methanol, ethanol, n-hexane, cyclohexane, xylene, acetone and the like.
[0013] As a preferred solution of a silicone rubber heat protection material containing modified silicon micropowder, the modified silicon micropowder is spherical modified silicon micropowder, and the particle size of the modified silicon micropowder is 0.2-5 um.
[0014] As a preferred embodiment of a silicone rubber heat protection material containing modified silica powder, the base rubber includes organosilicon polysiloxane, and the functional segments of the organosilicon polysiloxane include one or more of methyl, ethyl, vinyl, phenyl, phenylene, and phenylene ether.
[0015] As a preferred solution of a silicone rubber heat protection material containing modified silica powder, the functional filler includes one or more of a fiber filler, a flame retardant filler and an organic resin reinforced filler.
[0016] As a preferred solution of a silicone rubber thermal protection material containing modified silicon micropowder, the fiber filler includes one or more of carbon fiber, glass fiber, rock wool fiber, and aramid fiber; the flame retardant filler includes one or more of magnesium hydroxide, aluminum hydroxide, diethyl aluminum hypophosphite, and silicate; the organic resin reinforcing filler includes one or both of MQ silicone resin and phenolic resin.
[0017] As a preferred embodiment of a silicone rubber thermal protection material containing modified silicon micropowder, the crosslinking agent includes one or more of tetrapropoxysilane, aminopropyltriethoxysilane, tetraethoxysilane, a hydrogen-containing crosslinking agent, vinyltrimethoxysilane, aminopropylaminoethyltrimethoxysilane, and aminopropyltrimethoxysilane.
[0018] As a preferred solution of the silicone rubber heat protection material containing modified silicon micropowder, the catalyst includes one or more of dibutyltin dilaurate and platinum catalyst.
[0019] A method for preparing a silicone rubber heat protection material containing modified silicon micropowder, based on any of the above-mentioned silicone rubber heat protection materials containing modified silicon micropowder, the preparation method comprises the following steps:
[0020] Mix the base rubber, modified silica powder and functional filler evenly according to the proportion;
[0021] The reaction is carried out under vacuum, and then the pressure is released, and a cross-linking agent and a catalyst in corresponding proportions are added and mixed evenly to obtain a mixed product;
[0022] Finally, the mixed product is prepared through a spraying molding process to obtain a silicone rubber heat protection material sheet.
[0023] The beneficial effects of the present invention are:
[0024] The present invention provides a silicone rubber heat protection material containing modified silicon micropowder. The modified silicon micropowder is used to replace a conventional fumed silica reinforcing agent for preparing the silicone rubber heat protection material. The modified silicon micropowder has excellent dispersibility, fluidity and low thermal expansion coefficient in the silicone rubber system, so that the silicone rubber heat protection material can be sprayed and is not easy to expand and crack during heating, thereby having excellent anti-ablation performance. In addition, the surface of the modified silicon micropowder has highly active cross-linking sites, which can be used in the silicone rubber system to further react and graft with a base rubber and a cross-linking agent to improve the mechanical properties of the material. BRIEF DESCRIPTION OF THE DRAWINGS
[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the contents of the embodiments of the present invention and these drawings without paying any creative work.
[0026] Figure 1 This is a diagram showing the effect of the silicone rubber thermal protection material prepared in Example 1 after oxygen-acetylene ablation;
[0027] Figure 2 This is a picture showing the effect of the silicone rubber thermal protection material prepared in Comparative Example 1 after oxygen-acetylene ablation;
[0028] Figure 3 It is the structural formula of octa(phenyldimethoxysilyl) cage-shaped silsesquioxane;
[0029] Figure 4 It is the structural formula of octamethylammonium cage-type silsesquioxane. DETAILED DESCRIPTION
[0030] For ease of understanding of the present invention, the present invention will be described more fully below. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive. Unless otherwise defined, all technical and scientific terms used in the present invention belong to the technical field of the present invention.
[0031] An embodiment of the present invention provides a silicone rubber thermal protection material containing modified silicon micropowder, comprising the following raw material compositions in parts by mass: 100 parts of base rubber, 20 to 50 parts of modified silicon micropowder, 10 to 50 parts of functional filler, 5 to 15 parts of cross-linking agent, and 0.1 to 5 parts of catalyst, wherein the modified silicon micropowder comprises silicon micropowder modified with octa(phenyldimethoxysilyl) cage-shaped silsesquioxane.
[0032] Specifically, the base glue includes silicone polysiloxane, and the functional segments of the silicone polysiloxane include one or more of methyl, ethyl, vinyl, phenyl, phenylene, phenylene ether, and the like.
[0033] Specifically, the functional filler includes one or more of fiber filler, flame retardant filler and organic resin reinforced filler; the fiber filler includes one or more of carbon fiber, glass fiber, rock wool fiber and aramid fiber; the flame retardant filler includes one or more of magnesium hydroxide, aluminum hydroxide, diethyl aluminum hypophosphite and silicate; the organic resin reinforced filler includes one or two of MQ silicone resin and phenolic resin.
[0034] Specifically, the crosslinking agent includes one or more of tetrapropoxysilane, aminopropyltriethoxysilane, tetraethoxysilane, hydrogen-containing crosslinking agent, vinyltrimethoxysilane, aminopropylaminoethyltrimethoxysilane, and aminopropyltrimethoxysilane; the catalyst includes one or more of dibutyltin dilaurate and platinum catalyst.
[0035] Specifically, the preparation method of modified silicon micropowder includes: first heating the silicon micropowder to 80-100°C and ball-milling for 5-30 minutes, then adding octa(phenyldimethoxysilyl) cage-shaped silsesquioxane for grinding, and heating to 120-150°C for insulation reaction for 10-30 minutes to obtain modified silicon micropowder; wherein the mass of the modifier is 0.1% to 1% of the mass of the silicon micropowder, preferably 1% in this embodiment, and can also be selected as 0.1% or 0.5% in other embodiments, which is determined according to actual application requirements, and the particle size of the silicon micropowder is 0.2 to 5um.
[0036] More specifically, the silicon micropowder includes one of angular silicon micropowder and spherical silicon micropowder, wherein angular silicon micropowder is mostly used in low-end material systems, mainly in the field of coatings, and has lower cost; spherical silicon micropowder is used in copper clad laminates, epoxy molding compounds and rubber fields. In the present application, spherical silicon micropowder is preferred. The spherical morphology is conducive to slowing down heat transfer during heating, and the reinforcement and viscosity reduction properties are more excellent, which has a more excellent effect on improving the performance of thermal protection materials.
[0037] More specifically, the synthesis method of octa(phenyldimethoxysilyl) cage-type silsesquioxane is a functional group conversion method, and the synthesis process is: using octa(tetramethylammonium) cage-type silsesquioxane (the structural schematic diagram of octa(tetramethylammonium) cage-type silsesquioxane is as shown in Figure 4 As shown) and phenyldimethoxychlorosilane are added to a dissolving solvent in a molar ratio of 1: (8-10), and the reaction time is 12-72 hours at a temperature of -10°C to 100°C; the dissolving solvent includes one or more of toluene, methanol, ethanol, n-hexane, cyclohexane, xylene, acetone, etc.
[0038] The present invention also provides a method for preparing a silicone rubber thermal protection material containing modified silicon powder, comprising the following steps:
[0039] The base rubber, modified silicon micropowder and functional filler are mixed evenly in proportion; a vacuum reaction is carried out under negative pressure, and then the pressure is released and a corresponding proportion of cross-linking agent and catalyst are added and mixed evenly to obtain a mixed product; finally, the mixed product is prepared by a spray molding process to obtain a silicone rubber thermal protection material film.
[0040] The present invention will be further described below by means of specific examples.
[0041] Example 1
[0042] Preparation of modified silicon powder:
[0043] 100g of spherical silicon micropowder with an average particle size of 0.2um was added to a ball mill, heated to 90°C for 30min, and then 1.0g of octa(phenyldimethoxysilyl) cage-shaped silsesquioxane modifier was added, ground and heated to 135°C for 20min, and the modified silicon micropowder was obtained.
[0044] Preparation of silicone rubber thermal protection material:
[0045] 100 g of terminal hydroxyphenyl vinyl polysiloxane, 50 g of modified silicon powder, 15 g of carbon fiber, and 15 g of magnesium hydroxide were mixed evenly, and the above materials were mixed evenly using a dynamic mixer, and vacuumed at 120° C. for 30 min under a negative pressure environment of -0.09 MPa, and then 15 g of tetrapropoxysilane and 1 g of dibutyltin dilaurate were added after depressurization, and the mixture was quickly stirred for 15 min to mix evenly;
[0046] A 3 mm thick silicone rubber thermal protection material film was prepared by spraying molding method for testing mechanical properties and ablation properties.
[0047] Example 2
[0048] Preparation of silicone rubber thermal protection material:
[0049] 100 g of terminal hydroxyphenyl ether-supported polysiloxane, 20 g of modified silicon powder (prepared in accordance with Example 1), 10 g of aramid fiber, and 10 g of hollow spherical magnesium silicate were mixed evenly, and the above materials were mixed evenly using a dynamic mixer, and vacuumed at 120° C. for 30 min under a negative pressure environment of -0.09 MPa, and then 8 g of aminopropyl triethoxysilane, 2 g of tetraethoxysilane, and 0.1 g of dibutyltin dilaurate were added after decompression, and the mixture was quickly stirred for 15 min to mix evenly;
[0050] A 3 mm thick silicone rubber thermal protection material film was prepared by spraying molding method for testing mechanical properties and ablation properties.
[0051] Example 3
[0052] Preparation of silicone rubber thermal protection material:
[0053] 100g of vinylphenyl polysiloxane, 35g of modified silicon powder (prepared in accordance with Example 1), 15g of silicon carbide, 5g of phenolic resin, 10g of MQ silicone resin, and 10g of basalt fiber were mixed evenly, and the above materials were mixed evenly using a dynamic mixer. Vacuum was drawn at 120°C for 30min under a negative pressure of -0.09MPa, and then 5g of hydrogen-containing crosslinking agent and 5g of platinum catalyst were added after decompression, and the mixture was mixed evenly by rapid stirring for 15min.
[0054] A 3 mm thick silicone rubber thermal protection material film was prepared by spraying molding method for testing mechanical properties and ablation properties.
[0055] In order to further illustrate the key points of this patent, a comparative case is added for illustration.
[0056] Comparative Example 1
[0057] 100 g of terminal hydroxyphenyl vinyl polysiloxane, 50 g of fumed silica, 15 g of carbon fiber, and 15 g of magnesium hydroxide were mixed evenly, and the above materials were mixed evenly using a dynamic mixer, and vacuumed at 120° C. for 30 min under a negative pressure environment of -0.09 MPa, and then 15 g of tetrapropoxysilane and 1 g of dibutyltin dilaurate were added after depressurization, and the mixture was quickly stirred for 15 min to mix evenly;
[0058] A 3 mm thick silicone rubber thermal protection material film was prepared by spraying molding method for testing mechanical properties and ablation properties.
[0059] Comparative Example 2
[0060] 100 g of terminal hydroxyphenyl ether-supported polysiloxane, 20 g of fumed silica, 10 g of aramid fiber, and 10 g of hollow spherical magnesium silicate were mixed evenly, and the above materials were mixed evenly using a dynamic mixer, and vacuumed at 120° C. for 30 min under a negative pressure of -0.09 MPa, and then 8 g of aminopropyl triethoxysilane, 2 g of tetraethoxysilane, and 0.1 g of dibutyltin dilaurate were added after depressurization, and the mixture was quickly stirred for 15 min to mix evenly;
[0061] A 3 mm thick silicone rubber thermal protection material film was prepared by spraying molding method for testing mechanical properties and ablation properties.
[0062] Comparative Example 3
[0063] 100g vinyl phenyl polysiloxane, 35g fumed silica, 15g silicon carbide, 5g phenolic resin, 10g MQ silicone resin and 10g basalt fiber were mixed evenly and mixed evenly using a dynamic mixer. Vacuum was drawn at 120℃ for 30min under a negative pressure of -0.09MPa, and then 5g hydrogen-containing crosslinking agent and 5g platinum catalyst were added after depressurization, and the mixture was mixed evenly by rapid stirring for 15min.
[0064] A 3 mm thick silicone rubber thermal protection material film was prepared by spraying molding method for testing mechanical properties and ablation properties.
[0065] The silicone rubber thermal protection materials prepared in Example 1 and Comparative Example 1 were subjected to oxygen-acetylene ablation, and the effect diagrams thereof are shown as follows: Figure 1 and Figure 2 As shown in the figure, it can be seen that the silicone rubber thermal protection material prepared in Example 1 does not crack after ablation, and the silicone rubber thermal protection material prepared in Comparative Example 1 has large cracks after ablation. Therefore, the silicone rubber thermal protection material prepared in this application has excellent anti-ablation performance.
[0066] Examples 1-3 and comparative examples 1-3 were subjected to relevant performance tests, and their performance data are shown in Table 1. The test standards for tensile strength and elongation at break are GB / T 528-2009, and the test standard for line ablation rate is GJB 323B-2018.
[0067] Table 1 Summary of silicone rubber thermal protection material properties
[0068] Experiment No. Tensile strength / MPa Elongation at break / % Linear ablation rate / mm / s Cracking after ablation Example 1 3.6 120 0.19 No cracking Comparative Example 1 3.4 110 0.26 Large crack Example 2 4.0 150 0.10 No cracking Comparative Example 2 3.4 140 0.17 Micro cracks Example 3 2.0 40 0.09 No cracking Comparative Example 3 1.8 45 0.15 Large crack
[0069] It can be seen from the above data table that in the high-strength condensation silicone rubber thermal protection system of Examples 1-2 and Comparative Examples 1-2, as the internal thermal insulation material, the addition of modified silicon micropowder can improve the mechanical properties and anti-scouring properties of the silicone rubber thermal protection material. By comparing the tensile strength and elongation at break of Example 1 and Comparative Example 1 and Example 2 and Comparative Example 2, the tensile strength is increased by 5% to 15%, the elongation at break is increased by at least 5%, and the line ablation rate is greatly reduced, and the ablation cracking is significantly alleviated. In the addition-type silicone rubber thermal protection material system of Example 3 and Comparative Example 3, as an external thermal protection material, it is a high-filler formulation system, and the mechanical properties of the silicone rubber material are improved to a certain extent, but the improvement of the line ablation rate is more obvious, and the thermal cracking is also solved. The above-mentioned performance improvement is because when the silicone rubber thermal protection material is subjected to high-temperature ablation, the small molecules released after the silicone rubber is decomposed by heat cause the material to expand, thereby causing cracking and falling off. When the silicone rubber thermal protection material with the addition of modified silicon micropowder is decomposed by heat to release small molecules, tiny channels are provided between the spherical silicon micropowders. At the same time, the thermal expansion coefficient of the silicon micropowder is low, and the overall deformation of the silicone rubber thermal protection material is small, making it not easy to crack.
[0070] The above are only preferred embodiments of the present invention and the technical principles used. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention is described in more detail through the above embodiments, the present invention is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present invention, and the scope of the present invention is determined by the scope of the appended claims.
Claims
1. A silicone rubber thermal protection material containing modified silicon micropowder, characterized in that: The raw material composition includes the following parts by weight: The modified silicon micropowder includes silicon micropowder modified with octa(phenyldimethoxysilyl) cage-shaped silsesquioxane.
2. The silicone rubber thermal protection material containing modified silicon powder according to claim 1, characterized in that: The structural formula of the octa(phenyldimethoxysilyl) cage-shaped silsesquioxane is: 。 3. The silicone rubber thermal protection material containing modified silicon powder according to claim 1, characterized in that: The preparation method of the octa(phenyldimethoxysilyl) cage-type silsesquioxane is as follows: octa(phenyldimethoxysilyl) cage-type silsesquioxane and phenyldimethoxychlorosilane are added to a dissolving solvent in a molar ratio of 1:(8-10), and the reaction time is 12-72 hours at a temperature of -10°C to 100°C; The dissolution aid solvent includes one or more of toluene, methanol, ethanol, n-hexane, cyclohexane, xylene, acetone and the like.
4. The silicone rubber thermal protection material containing modified silicon powder according to claim 1, characterized in that: The modified silicon micropowder is spherical modified silicon micropowder, and the particle size of the modified silicon micropowder is 0.2-5 um.
5. The silicone rubber thermal protection material containing modified silicon powder according to claim 1, characterized in that: The base glue comprises organosilicon polysiloxane, and the functional segments of the organosilicon polysiloxane comprise one or more of methyl, ethyl, vinyl, phenyl, phenylene, and phenylene ether.
6. The silicone rubber heat protection material containing modified silicon powder according to claim 1, characterized in that: The functional filler includes one or more of a fiber filler, a flame retardant filler and an organic resin reinforced filler.
7. The silicone rubber heat protection material containing modified silicon powder according to claim 6, characterized in that: The fiber filler includes one or more of carbon fiber, glass fiber, rock wool fiber, and aramid fiber; the flame retardant filler includes one or more of magnesium hydroxide, aluminum hydroxide, diethyl aluminum hypophosphite, and silicate; the organic resin reinforcing filler includes one or both of MQ silicone resin and phenolic resin.
8. The silicone rubber thermal protection material containing modified silicon powder according to claim 1, characterized in that: The crosslinking agent includes one or more of tetrapropoxysilane, aminopropyltriethoxysilane, tetraethoxysilane, a hydrogen-containing crosslinking agent, vinyltrimethoxysilane, aminopropylaminoethyltrimethoxysilane, and aminopropyltrimethoxysilane.
9. The silicone rubber heat protection material containing modified silicon powder according to claim 1, characterized in that: The catalyst includes one or more of dibutyltin dilaurate and platinum catalyst.
10. A method for preparing a silicone rubber thermal protection material containing modified silicon micropowder, characterized in that: The preparation method of the silicone rubber thermal protection material containing modified silicon micropowder according to any one of claims 1 to 9 comprises the following steps: Mix the base rubber, modified silica powder and functional filler evenly according to the proportion; The reaction is carried out under vacuum, and then the pressure is released, and a cross-linking agent and a catalyst in corresponding proportions are added and mixed evenly to obtain a mixed product; Finally, the mixed product is prepared through a spraying molding process to obtain a silicone rubber heat protection material sheet.