High-heat-insulation ceramic silica gel foam

Abstract

The invention discloses high-heat-insulation ceramic silica gel foam, and relates to the technical field of high-temperature-resistant silica gel. The high-heat-insulation ceramic silica gel foam is prepared from the following components in parts by mass: 100 parts of methyl vinyl silicone rubber, 15 to 40 parts of ceramic silicon resin, 15 to 25 parts of a flame retardant, 3 to 15 parts of fumed silica, 0.5 to 5 parts of hydrogen-containing silicone oil, 0.1 to 2 parts of a platinum catalyst, 2 to 10 parts of an azodicarbonamide foaming agent, 1 to 8 parts of a ceramic accelerant, 0.5 to 3 parts of a heat-resistant additive and 5 to 8 parts of reinforcing filler. Compared with the prior art, the material disclosed by the invention can quickly form a compact ceramic layer at a high temperature, can more effectively block heat transfer, avoids sharp reduction of mechanical properties or structural damage of the material in a high-temperature environment, and is more excellent in high-temperature use stability.

Description

Technical Field

[0001] This invention relates to the field of high-temperature resistant silicone technology, specifically to a high-insulation ceramicized silicone foam. Background Technology

[0002] With the increasing demands for safety performance in modern industry and construction, the need for high-efficiency thermal insulation and flame-retardant materials is becoming increasingly urgent. In aerospace, new energy vehicles, electronic equipment, and building insulation, materials not only need excellent thermal insulation performance but also must maintain structural integrity under high-temperature or fire conditions to prevent the spread of fire. Traditional thermal insulation materials such as asbestos, rock wool, and polyurethane foam generally suffer from low thermal insulation efficiency, easy decomposition at high temperatures, release of toxic gases, or poor mechanical properties.

[0003] Silicone-based materials are widely used in thermal insulation due to their excellent heat resistance and chemical stability. However, ordinary silicone foam is prone to thermal degradation at temperatures above 300℃, resulting in a sharp decrease in mechanical strength and limited flame retardant properties. Although some studies have improved performance by adding inorganic flame retardants such as aluminum hydroxide and magnesium hydroxide, this often leads to reduced material flexibility, increased density, and difficulty in maintaining structural stability at extreme temperatures. Ceramicized silicone is a new type of high-temperature resistant material developed in recent years. Its characteristic is that under high-temperature combustion conditions, a dense ceramic layer can be rapidly formed on the surface of the material, effectively isolating heat transfer and preventing flame spread. However, existing ceramicized silicone materials often suffer from insufficient thermal insulation efficiency, excessively high ceramicization temperature, high cost, or complex processing technology. Especially in applications requiring both high flexibility and high thermal insulation performance, the market lacks ideal products. Furthermore, with increasingly stringent environmental regulations, halogen-free flame retardancy and low smoke toxicity have become important considerations. Currently, many high-performance flame retardant materials still rely on halogenated flame retardants, which release toxic and corrosive gases during combustion, which is inconsistent with the trend of green development. Therefore, developing a ceramicized silicone foam material that combines excellent thermal insulation performance, high efficiency halogen-free flame retardancy, good flexibility, and reasonable cost has become a technical challenge that the industry urgently needs to solve. Summary of the Invention

[0004] The purpose of this invention is to address the problems existing in the prior art by providing a high-insulation ceramicized silicone foam material. This material has excellent thermal insulation performance, halogen-free flame retardant properties, and good flexibility. It can be rapidly ceramicized at high temperatures to form a dense protective layer, effectively blocking heat transfer and flame spread. At the same time, it has advantages such as low smoke and non-toxicity, low density, and reasonable cost, making it suitable for high-safety-requirement fields such as aerospace and new energy vehicles.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A high-insulation ceramicized silicone foam, by weight, comprises the following components: 100 parts methyl vinyl silicone rubber, 15-40 parts ceramicized silicone resin, 15-25 parts flame retardant, 3-15 parts fumed silica, 0.5-5 parts hydrogen-containing silicone oil, 0.1-2 parts platinum catalyst, 2-10 parts azodicarbonamide blowing agent, 1-8 parts ceramicization accelerator, 0.5-3 parts heat-resistant additive, and 5-8 parts reinforcing filler; wherein the flame retardant is a compound represented by Formula 1. Formula 1 R1 in Formula 1 is selected from any one of the following: alkyl groups having 1-5 carbon atoms, or alkyl groups having 1-5 carbon atoms that have been substituted with hydroxyl groups.

[0006] Furthermore, by adopting the above technical solution, the ceramicized silicone resin is a mixture of phenyl silicone resin and methyl silicone resin in a mass ratio of 1:0.3-3.

[0007] By adopting the above technical solution, the ceramicization accelerator is further selected from one or more combinations of zinc borate, zinc oxide, sodium silicate, and barium metaborate.

[0008] Furthermore, by adopting the above technical solution, the heat-resistant additive is a cerium compound or an iron compound.

[0009] Furthermore, by adopting the above technical solution, the reinforcing filler is silicon dioxide.

[0010] Furthermore, by adopting the above technical solution, the cerium compound is selected from any one of cerium oxide, cerium stearate, cerium naphthenate, cerium acetate, and cerium nitrate. Furthermore, by adopting the above technical solution, the iron compound is selected from any one of ferric oxide, ferric oxide, zinc ferrite, ferric stearate, and ferric naphthenate.

[0011] Furthermore, by adopting the above technical solution, the flame retardant is any one of the compounds shown in the following structures: ; ; .

[0012] A method for preparing high-insulation ceramicized silicone foam includes the following steps: (a) The methyl vinyl silicone rubber is plasticized on a two-mill until uniform, and the fumed silica, flame retardant, ceramicized silicone resin, ceramicization accelerator, heat-resistant additive and reinforcing filler are added in sequence and mixed evenly to obtain mixture A. (b) Add hydrogen-containing silicone oil, platinum catalyst and azodicarbonamide foaming agent to the mixture A in sequence, and continue to mix until uniform to obtain mixture B; (c) Place the mixture B in a mold and pre-vulcanize it at 150-180℃ for 5-15 minutes. Transfer the pre-vulcanized product to a foaming equipment and foam and vulcanize it again at 200-250℃ for 10-30 minutes. After cooling, demold to obtain a high heat insulation ceramicized silicone foam.

[0013] By adopting the above technical solution, the pre-vulcanization temperature is further 160-170℃, and the time is 8-12 minutes.

[0014] By adopting the above technical solution, the foaming temperature is further 220-240℃ and the time is 15-25 minutes.

[0015] Furthermore, by adopting the above technical solution, step (a) is carried out under a nitrogen atmosphere. Furthermore, by adopting the above technical solution, fluorosilicone rubber or polyvinyl chloride may also be added to the high-insulation ceramicized silicone foam.

[0016] This invention addresses the technical problems of existing materials, such as low thermal insulation efficiency, unstable high-temperature structure, toxicity in flame retardants, and poor flexibility, through the proportioning and synergistic effect of the components. It uses methyl vinyl silicone rubber as the base material to ensure basic flexibility, combined with a ceramicized silicone resin composed of phenyl silicone resin and methyl silicone resin, and incorporates ceramicization accelerators such as zinc borate to rapidly form a dense ceramic layer at high temperatures, effectively blocking heat and flame spread. A novel, specifically structured halogen-free flame retardant, combined with cerium / iron compound heat-resistant additives, achieves both high-efficiency flame retardancy and avoids the release of toxic gases from halogen-based flame retardants, while simultaneously improving the material's resistance to temperatures above 300°C. High-temperature stability; the synergistic effect of fumed silica and silica reinforcing filler enhances mechanical strength without reducing flexibility, compensating for the excessive rigidity of materials caused by traditional inorganic flame retardants; hydrogen-containing silicone oil and platinum catalyst ensure sufficient vulcanization reaction, while azodicarbonamide foaming agent enables the material to form a low-density cell structure, further optimizing thermal insulation performance; the mixing under nitrogen atmosphere and the precisely controlled pre-vulcanization and foaming secondary vulcanization process ensure the synergistic effect of each component is maximized, ultimately resulting in ceramicized silicone foam with high thermal insulation, halogen-free and low smoke, good flexibility and structural stability, meeting the application requirements of high safety requirements.

[0017] Compared with the prior art, the beneficial effects of the present invention are: 1. Significantly improved thermal insulation performance and high-temperature structural stability: Compared with existing technologies, the material of this invention can quickly form a dense ceramic layer at high temperatures, which can more effectively block heat transfer and avoid a sharp decline in the mechanical properties of the material or structural damage under high-temperature conditions, resulting in better stability in high-temperature use.

[0018] 2. Simultaneous optimization of flame retardant performance and environmental friendliness: Abandoning the existing technology that partially relies on halogen-based flame retardants, a specific structure halogen-free flame retardant system is adopted. While improving the flame retardant effect, it avoids the release of toxic and corrosive gases during combustion, achieving low smoke and non-toxic characteristics, which is more in line with environmental protection regulations.

[0019] 3. Synergistic improvement of mechanical properties and flexibility: It solves the problem that adding inorganic flame retardants in traditional technology can easily lead to a decrease in material flexibility and excessive rigidity. Through the synergistic design of components, it can maintain good flexibility while ensuring the mechanical strength of the material, making it more suitable for application scenarios that require the material's deformation capacity. Attached Figure Description

[0020] Figure 1 This is the NMR spectrum of the flame retardant 1 described in this invention. Detailed Implementation

[0021] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] Preparation of Flame Retardant 1 in Example 1: ; Under a nitrogen atmosphere, 5 g of compound 1 and 50 ml of dichloromethane were added sequentially to the reaction system. After stirring until homogeneous, 22.57 g of N,N-diisopropylethylamine was added and stirred until homogeneous. The air was then replaced twice with nitrogen, and the system temperature was lowered to 0°C with dry ice. A 20 ml dichloromethane solution containing 7.77 g of triphosgene was slowly added dropwise, and the system temperature was maintained at 0°C. The mixture was stirred for 2 hours. Then, a 20 ml dichloromethane solution containing 5.41 g of compound 2 was added to the reaction system, and the system was brought to room temperature and stirred for another 16 hours. After the reaction was complete, 1500 ml of water was added for quenching. After stirring, shaking, and separation, the organic phase was retained. The organic phase was dried with anhydrous sodium sulfate, filtered to remove the desiccant, and evaporated to dryness to obtain the crude product. The crude product was purified by silica gel column chromatography (eluent: a mixture of petroleum ether and ethyl acetate). The eluent was evaporated to dryness to obtain 7.46 g of the target compound 3. The mass spectrometry showed an MS+1 of 622. Compound 3: Ethyl P-(chloro(phenyl)methyl)-N-(1-((diethoxyphosphono)(phenyl)methyl)-2,2-dimethylhydrazyl-1-carboxyl)-N-phenylphosphonamide; ; Under a nitrogen atmosphere, 7.46 g of compound 3, 1.10 g of compound 4, and 90 mL of a mixed solvent of dioxane and diisopropylamine (60 mL / 30 mL) were added sequentially to the reaction system. After stirring until homogeneous, 0.04 g of target carbon, 0.17 g of 2-dicyclohexylphosphine-2',4',6'-triisopropylbiphenyl, and 0.07 g of CuI were added sequentially. The mixture was stirred until homogeneous, heated to 95 °C, and refluxed for 6 h. After the reaction was completed, the mixture was cooled to room temperature and filtered. The filtrate was purified by silica gel column chromatography (eluent: a mixture of petroleum ether and ethyl acetate) using a rotary evaporator. The eluent was evaporated to dryness to obtain flame retardant 1 with a concentration of 5.91 g / mL. The mass spectrometry showed an MS+1 of 678, and the NMR results were as follows: [Insert NMR results here]. Figure 1 ; Flame retardant 1: Ethyl N-(1-((diethoxyphosphono)methyl)-2,2-dimethylhydrazyl-1-carboxyl)-P-(3-(furan-2-yl)-1-phenylprop-2-yn-1-yl)-N-phenylphosphonamide.

[0023] Preparation Examples 2-5: Flame retardant 2-Flame retardant 5 were prepared sequentially in Preparation Examples 2-Flame retardant 5, replacing compound 4. The rest were the same as in Preparation Example 1. See Table 1 for details.

[0024] Table 1 Example 1 Preparation of a high-insulation ceramicized silicone foam: 1. Raw material composition by weight: Methyl vinyl silicone rubber: 100 parts; Ceramicized silicone resin: 25 parts (12.5 parts phenyl silicone resin, 12.5 parts methyl silicone resin, mass ratio: 1); Flame retardant: 20 parts (using flame retardant 1 prepared in Preparation Example 1); Fumed silica: 8 parts; Hydrogen-containing silicone oil: 2 parts; Platinum catalyst: 0.8 parts (Castel catalyst, CAS number 68478-92-2); Azodicarbonamide foaming agent: 6 parts; Ceramification accelerator: 4 parts (zinc borate); Heat-resistant additive: 1.5 parts (cerium oxide); Reinforcing filler: 6.5 parts (silica).

[0025] 2. Preparation method: (a) Under a nitrogen atmosphere, place 100 parts of methyl vinyl silicone rubber in a two-roll mill and plasticize until homogeneous and free of obvious particulate impurities. Then, sequentially add 8 parts of fumed silica, 20 parts of flame retardant, 25 parts of ceramicized silicone resin (a blend of phenyl silicone resin and methyl silicone resin), 4 parts of zinc borate, 1.5 parts of cerium oxide, and 6.5 parts of silica. Maintain the two-roll mill temperature at 55°C and mix for 30 minutes until all components are evenly dispersed to obtain mixture A. (b) Add 2 parts of hydrogen-containing silicone oil, 0.8 parts of platinum catalyst and 6 parts of azodicarbonamide foaming agent to mixture A in sequence, and continue to mix in the open mill for 15 minutes to ensure that the foaming agent and vulcanization system are evenly dispersed to obtain mixture B; (c) Load mixture B into a custom mold and transfer it to a flat vulcanizing machine for pre-vulcanization. Set the temperature to 165°C and hold for 10 minutes. After pre-vulcanization, transfer the product to a foaming vulcanizing machine, raise the temperature to 230°C and hold for 20 minutes to simultaneously complete foaming and secondary vulcanization. After the equipment cools naturally to room temperature, demold to obtain the target high-insulation ceramicized silicone foam.

[0026] Examples 2-5 The preparation of a high heat insulation ceramicized silicone foam is carried out by referring to the preparation method of Example 1, except that the flame retardant is replaced with flame retardant 2-flame retardant 5 in sequence, and the rest is the same as in Example 1.

[0027] Comparative Example 1 The preparation of a high heat-insulating ceramicized silicone foam is carried out by referring to the preparation method of Example 1, except that the flame retardant is replaced with trioctyl phosphate, and the rest is the same as in Example 1.

[0028] Comparative Example 2 The preparation of a high heat-insulating ceramicized silicone foam is carried out by referring to the preparation method of Example 1, except that the flame retardant is replaced with tricresyl phosphate, and the rest is the same as in Example 1.

[0029] Comparative Example 3 The preparation of a high heat-insulating ceramicized silicone foam is carried out by referring to the preparation method of Example 1, except that the flame retardant is replaced with aluminum hydroxide, and the rest is the same as in Example 1.

[0030] Comparative Example 4 The preparation of a high-insulation ceramicized silicone foam is the same as in Example 1, except that no flame retardant is added.

[0031] Comparative Example 5 The preparation of a high heat-insulating ceramicized silicone foam is the same as in Example 1, except that no heat-resistant additives are added.

[0032] Comparative Example 6 The preparation of a high-insulation ceramicized silicone foam is the same as in Example 1, except that no reinforcing filler is added.

[0033] Performance testing: 1. Thermal insulation performance test: Refer to the test method of GB / T 10294-2008 to test the thermal conductivity. The data are shown in Table 2.

[0034] 2. Flame retardant performance test: Refer to the UL 94 test method to test the flame retardant rating. The data is shown in Table 2.

[0035] 3. Mechanical property testing: The tensile strength was tested according to the test method of GB / T 528-2009. The data are shown in Table 2.

[0036] Table 2 The embodiments using the flame retardant with the specific structure of the present invention exhibit better overall thermal insulation performance than the comparative examples with replaced flame retardants, no added flame retardants, or no added heat-resistant additives, demonstrating superior heat barrier effect. Regarding flame retardancy, the embodiments maintain a higher flame retardancy rating, while the comparative examples with replaced traditional flame retardants or no added flame retardants show a decrease in flame retardancy rating. In terms of mechanical properties, the tensile strength of the embodiments remains stable, while the tensile strength of the comparative examples without reinforcing fillers is significantly weakened, and the comparative examples without added heat-resistant additives also show a downward trend in mechanical properties. This indicates that the synergistic effect of the components of the present invention (specific flame retardant, heat-resistant additives, reinforcing fillers, etc.) can simultaneously ensure high thermal insulation, efficient flame retardancy, and good mechanical stability of the material.

[0037] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A highly thermally insulating ceramifiable silica gel foam, characterized in that, By mass parts, comprising the following components: 100 parts of methyl vinyl silicone rubber, 15-40 parts of ceramic silicon resin, 15-25 parts of flame retardant, 3-15 parts of fumed silica, 0.5-5 parts of hydrogen-containing silicone oil, 0.1-2 parts of platinum gold catalyst, 2-10 parts of azobisformamide foaming agent, 1-8 parts of ceramic promoting agent, 0.5-3 parts of heat-resistant additive, 5-8 parts of reinforcing filler; The flame retardant is a compound represented by formula 1. Formula 1 R1 in formula 1 is selected from any one of alkyl with carbon number 1-5, alkyl with carbon number 1-5 substituted by hydroxyl.

2. The highly thermally insulating ceramicized silica gel foam according to claim 1, characterized in that, The ceramic silicon resin is a mixture of phenyl silicone resin and methyl silicone resin, with a mass ratio of 1:0.3-3.

3. The highly thermally insulating ceramicized silica gel foam according to claim 1, wherein, The ceramic promoting agent is selected from one or more combinations of zinc borate, zinc oxide, sodium silicate, barium metaborate.

4. The highly thermally insulating ceramicized silica gel foam according to claim 1, wherein, The heat-resistant additive is a cerium compound or an iron compound.

5. The highly thermally insulating ceramicized silica gel foam according to claim 1, wherein, The reinforcing filler is silicon dioxide.

6. The highly thermally insulating ceramicized silica gel foam according to claim 4, wherein, The cerium compound is selected from any one of cerium oxide, cerium stearate, cerium naphthenate, cerium acetate, cerium nitrate; The iron compound is selected from any one of diiron trioxide, ferriferrous oxide, zinc ferrite, iron stearate, iron naphthenate.

7. The highly thermally insulating ceramicized silica gel foam according to claim 1, wherein, The flame retardant is any one of the compounds represented by the following structure: ； ； 。 8. A method for preparing a high thermal insulation ceramicized silica gel foam according to any one of claims 1 to 7, characterized in that, The method comprises the following steps: (a) plasticize the methyl vinyl silicone rubber on the open mill to be uniform, add the fumed silica, flame retardant, ceramic silicon resin, ceramic promoting agent, heat-resistant additive and reinforcing filler in turn, mix uniformly to obtain a mixture A; (b) add the hydrogen-containing silicone oil, platinum gold catalyst and azobisformamide foaming agent to the mixture A in turn, continue to mix until uniform to obtain a mixture B; (c) place the mixture B in a mold, pre-vulcanize at 150-180℃ for 5-15 minutes, transfer the pre-vulcanized product to a foaming device, and carry out foaming and secondary vulcanization at 200-250℃ for 10-30 minutes, demold after cooling to obtain a high thermal insulation ceramic silicone foam.

9. The method of claim 8, wherein the ceramicized silica aerogel foam has a thermal conductivity of less than 20 mW / m-K. The pre-vulcanization temperature is 160-170℃, and the time is 8-12 minutes; The foaming temperature is 220-240℃, and the time is 15-25 minutes.

10. The method of claim 8, wherein the ceramicized silica aerogel foam has a thermal conductivity of less than 20 mW / m-K. The step (a) is carried out under nitrogen atmosphere.

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