High-temperature resistant and flame-retardant solid silicone composition, its preparation method and application

Abstract

The present invention belongs to the technical field of silicone, and specifically relates to a high-temperature resistant and flame-retardant solid silicone composition, its preparation method and application. The high-temperature resistant and flame-retardant solid silicone composition, by mass, comprises: 100 parts of methyl vinyl silicone rubber raw rubber, 20-30 parts of organically coated nano-fillers, 8-12 parts of flame retardant, 6-10 parts of hydroxyl silicone oil, 5-10 parts of polytetrafluoroethylene ultrafine powder, 3-8 parts of vulcanizing agent, and 0.5-1.5 parts of mold release agent; the flame retardant is a hollow multi-layer carbon microsphere / ionic liquid composite; the high-temperature resistant and flame-retardant solid silicone composition provided by the present invention has excellent high-temperature resistance, flame retardancy and high-temperature edible oil resistance.

Description

Technical Field

[0001] The present invention belongs to the technical field of silicone, and particularly relates to a high-temperature resistant and flame-retardant solid silicone composition, a preparation method thereof, and an application thereof. Background Art

[0002] Due to its good electrical insulation, silicone has a wide range of applications in household kitchen appliances, and can provide sealing, insulation and protection, thereby improving the performance and service life of household kitchen appliances. However, the ordinary silicone has a low temperature resistance and cannot meet the requirements of kitchen appliances such as microwave ovens, air fryers, and ovens with a maximum temperature of up to 250 °C and above.

[0003] Chinese Patent No. CN117106308A in the prior art discloses a one-component alcohol-decomposing type high-temperature resistant silicone rubber for the household appliance industry and a preparation method thereof, including the following components: polyalkyl-modified polymethyl(phenyl)silicone oil; heat-resistant filler treated with polyalkylsilicone oil; silicone resin; cross-linking agent; reinforcing filler; coupling agent; catalyst, which has the advantages of low odor, no corrosion, good adhesiveness, excellent high-temperature resistance, and alcohol-decomposing type, and can meet the high-temperature resistance application requirements of most household appliances. However, the mechanical properties of the silicone rubber obtained by this technical solution need to be improved, and this technical solution does not pay attention to the flame retardancy of the silicone rubber.

[0004] Chinese Patent No. CN117447845A discloses a flame-retardant and high-temperature resistant silicone rubber and a production process thereof. The composition includes the following weight components: (a) 90-100 parts of kneaded raw rubber, (b) 3-5 parts of high-vinyl silicone oil, (c) 0.5-1 part of tetrafluoroethylene powder, (d) 0.8-1.5 parts of methylphenyldiethoxysilane, (e) high-temperature resistant component, which consists of: 0.05-0.2 part of white carbon black, 3-5 parts of iron oxide; (f) flame retardant component, which consists of: 4-10 parts of decabromodiphenyl ether, 5-8 parts of antimony pentoxide; (g) additives, the additives include 1-10 parts of vulcanizing agent, 0.4-1 part of mold release agent and 0.5-5 parts of catalyst; the weight of components (a)-(g) accounts for 90-100% of the total weight of the composition, calculated based on the total weight of the composition. The silicone rubber of this technical solution improves the high-temperature resistance and flame retardancy by improving the proportioning of raw material components and the production process, and mixing the raw materials of the silicone rubber with various automatic processing equipment to simplify its batching process. However, the flame retardants decabromodiphenyl ether and antimony pentoxide used in this technical solution may cause harm to the human body, so there are potential hazards when applied to household kitchen appliances. Summary of the Invention

[0005] In view of the above problems, the present invention provides a high-temperature resistant and flame-retardant solid silicone composition, its preparation method and application. The solid silicone composition of the present invention has excellent high-temperature resistance, flame retardancy and high-temperature cooking oil resistance.

[0006] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] In the first aspect of the present invention, a high-temperature resistant and flame-retardant solid silicone composition is provided. By mass, the raw materials include: 100 parts of methyl vinyl silicone rubber raw rubber, 20-30 parts of organically coated nano-fillers, 8-12 parts of flame retardant, 6-10 parts of hydroxy silicone oil, 5-10 parts of polytetrafluoroethylene ultrafine powder, 3-8 parts of vulcanizing agent, and 0.5-1.5 parts of mold release agent;

[0008] The flame retardant is a hollow multi-layer carbon microsphere / ionic liquid composite;

[0009] The nano-fillers are nano-oxides loaded with amorphous silica and hollow glass microspheres; the mass ratio of the nano-oxides loaded with amorphous silica to the hollow glass microspheres is (1-3):(0.5-1.5).

[0010] Preferably, the methyl vinyl silicone rubber raw rubber is vinyl-terminated methyl vinyl silicone rubber raw rubber.

[0011] Preferably, the methyl vinyl silicone rubber raw rubber is a mixture of methyl vinyl silicone rubber raw rubber with a vinyl content of 0.21-0.24% and methyl vinyl silicone rubber raw rubber with a vinyl content of 4-5%; the mass ratio of the two is (4-6):1, preferably 5:1.

[0012] Preferably, the methyl vinyl silicone rubber raw rubber with a vinyl content of 0.21-0.24% has a molecular weight of 550,000-700,000, preferably 620,000±20,000.

[0013] Preferably, the methyl vinyl silicone rubber raw rubber with a vinyl content of 4-5% has a molecular weight of 550,000-700,000, preferably 670,000±20,000.

[0014] Preferably, the hollow glass microspheres are of the C series produced by Zhongke Huaxing New Materials Co., Ltd., preferably model C100.

[0015] Preferably, the nano-oxides are nano-aluminum oxide, nano-silica and nano-cerium dioxide; the mass ratio of the nano-aluminum oxide, nano-silica and nano-cerium dioxide is (10-20):(10-20):(0.2-0.4), preferably 15:15:0.3.

[0016] Preferably, the preparation method of the organically coated nano-fillers includes the following steps:

[0017] Step 1: Add ammonia water to the nano-oxide solution, add tetraethyl orthosilicate at 30 - 40 °C, keep warm and stir for reaction for 8 - 12 h, and obtain the nano-oxide loaded with amorphous silica through centrifugation, washing and drying in sequence.

[0018] Step 2: Place the hollow glass microspheres in a sodium hydroxide solution, reflux and stir for reaction at 70 - 90 °C for 1 - 2 h, and obtain the pretreated hollow glass microspheres through washing and drying in sequence.

[0019] Step 3: Place the nano-oxide loaded with amorphous silica and the pretreated hollow glass microspheres in a reaction kettle, add sodium hydride, stir and heat up to 70 - 90 °C under nitrogen protection, slowly dropwise add 4-vinylbenzyl glycidyl ether, finish the dropwise addition within 1 h, continue to keep warm and stir for reaction for 6 - 8 h, and obtain the product after cooling at the end of the reaction.

[0020] The inventor of the present invention creatively uses a self-made organically coated nano-filler. First, load amorphous silica on the surface of the nano-oxide and pretreat the hollow glass microspheres with sodium hydroxide. The surface of the amorphous silica and the hollow glass microspheres pretreated with sodium hydroxide contain a large number of hydroxyl groups, enabling 4-vinylbenzyl glycidyl ether to be coated on its surface through ring-opening reaction with the hydroxyl groups; the organically coated nano-filler not only has good compatibility in the methyl vinyl silicone rubber system, enhancing the interfacial interaction strength between the nano-filler and the methyl vinyl silicone rubber, but also the benzene ring structure of 4-vinylbenzyl glycidyl ether improves the additional high-temperature resistance performance and can form a carbon layer at high temperature, further improving its flame retardancy; at the same time, the organically coated layer forms a protective film on the surface of the solid silicone composition, reducing the erosion of edible oil on it; the hollow glass microspheres pretreated with sodium hydroxide become rough, increasing the contact area with the nano-oxide and making their mutual stacking more compact; through the combined action of nano-aluminum oxide, nano-silica and nano-cerium dioxide in the nano-oxide, the oxidation reaction of the solid silicone composition at high temperature is reduced and the thermal degradation is lowered; through the combined action of the nano-oxide, the hollow glass microspheres and 4-vinylbenzyl glycidyl ether, the high-temperature resistant and flame-retardant solid silicone composition of the present invention not only has excellent mechanical properties at a high temperature of 300 °C, but also has good flame retardancy and high-temperature edible oil resistance.

[0021] Preferably, the preparation method of the nano-oxide solution is: Disperse 40 - 60 mg of nano-oxide in 100 mL of an ethanol aqueous solution.

[0022] Preferably, the ethanol aqueous solution is composed of ethanol and water with a mass ratio of 90 - 95:5 - 10.

[0023] Preferably, the volume ratio of the nano-oxide aqueous solution, ammonia water, and tetraethyl orthosilicate is 100:(3 - 5):(5 - 6).

[0024] Preferably, the mass fraction of the ammonia water is 25%.

[0025] Preferably, the mass-to-volume ratio of the hollow glass microspheres to the sodium hydroxide solution is (0.02 - 0.04) g:1 mL.

[0026] Preferably, the concentration of the sodium hydroxide solution is 0.3 - 0.5 mol / L.

[0027] Preferably, the addition amount of sodium hydride is 0.2 - 0.5% of the total mass of the nano-oxide loaded with amorphous silica and the hollow glass microspheres.

[0028] Preferably, the addition amount of 4-vinylbenzyl glycidyl ether is 55 - 65% of the total mass of the nano-oxide loaded with amorphous silica and the hollow glass microspheres.

[0029] Preferably, the preparation method of the hollow multi-layer carbon microsphere / ionic liquid composite comprises the following steps:

[0030] S1. Mix the melamine solution and the cyanuric acid solution evenly, react at 25 - 35 °C for 20 - 30 min, and sequentially perform centrifugation, washing, and drying to obtain melamine cyanurate composite microspheres;

[0031] S2. Mix the melamine cyanurate composite microsphere solution and the dopamine solution evenly, stir at 25 - 35 °C for 20 - 40 min, then add Tris buffer solution, and react at 25 - 35 °C for 10 - 15 h, and sequentially perform centrifugation, washing, and drying to obtain poly-dopamine-coated melamine cyanurate composite microspheres;

[0032] S3. Place the poly-dopamine-coated melamine cyanurate composite microspheres in an inert atmosphere, first keep them at 400 - 500 °C for 2 - 3 h, and then keep them at 750 - 850 °C for 2 - 3 h to obtain hollow multi-layer carbon microspheres;

[0033] S4. Place the hollow multi-layer carbon microspheres in a vacuum environment, dropwise add the ionic liquid, and after the addition is completed, sequentially perform washing and drying to obtain the product.

[0034] The present inventor creatively uses a self-made hollow multi-layer carbon microsphere / ionic liquid composite. First, melamine cyanurate composite microspheres are prepared, then coated with polydopamine, and then calcined to obtain hollow multi-layer carbon microspheres. Finally, the ionic liquid can be adsorbed on the inside and surface of the hollow multi-layer carbon microspheres. The hollow multi-layer carbon microspheres form a stable carbon layer at high temperature, isolating oxygen and heat, effectively inhibiting the spread of fire. At the same time, the flame retardant elements in the ionic liquid prevent further oxidation of the carbon layer, thus having excellent flame retardant properties. Meanwhile, the hollow structure and multi-layer structure of the hollow multi-layer carbon microspheres have a large specific surface area, strong interfacial interaction with methyl vinyl silicone rubber, and excellent high thermal stability. Through the combined action of the hollow multi-layer carbon microspheres and the ionic liquid, the high-temperature resistant and flame retardant solid silicone composition of the present invention has excellent flame retardancy and also improves the high-temperature resistance.

[0035] Preferably, the preparation method of the melamine solution is: dissolving 0.4 - 0.6 g of melamine in 15 - 20 mL of dimethyl sulfoxide.

[0036] Preferably, the preparation method of the cyanuric acid solution is: dissolving 0.4 - 0.6 g of cyanuric acid in 5 - 15 mL of dimethyl sulfoxide.

[0037] Preferably, the volume ratio of the melamine solution to the cyanuric acid solution is (1.5 - 2):1.

[0038] Preferably, the preparation method of the melamine cyanurate composite microsphere solution is: dissolving 0.4 - 0.6 g of melamine cyanurate composite microspheres in 100 mL of water.

[0039] Preferably, the preparation method of the dopamine solution is: dissolving 0.4 - 0.6 g of dopamine hydrochloride in 100 mL of water.

[0040] Preferably, the preparation method of the Tris buffer solution is: dissolving 0.4 - 0.6 g of tris(hydroxymethyl)aminomethane in 100 mL of water.

[0041] Preferably, the volume ratio of the melamine cyanurate composite microsphere solution, the dopamine solution and the Tris buffer solution is 1:1:1.

[0042] Preferably, the mass ratio of the hollow multi-layer carbon microspheres to the ionic liquid is 1:(30 - 40).

[0043] Preferably, the ionic liquid includes 1-ethyl acetate-3-methylimidazolium hexafluorophosphate and / or 1-ethyl acetate-3-methylimidazolium tetrafluoroborate.

[0044] Preferably, the hydroxyl content in the hydroxyl silicone oil is 8 - 10 wt%, and the viscosity is 30 - 35 mm2 / s, preferably, the hydroxyl content in the hydroxyl silicone oil is 9 wt%, and the viscosity is 30 mm 2 / s.

[0045] Preferably, the polytetrafluoroethylene ultrafine powder includes polytetrafluoroethylene ultrafine powder with a particle size distribution of D50 < 5.0 μm and D90 < 10 μm and polytetrafluoroethylene ultrafine powder with a particle size distribution of D50 < 11 μm and D90 < 15 μm; the mass ratio of the two is (2 - 4):1.

[0046] Preferably, the mass ratio of the organically coated nano filler, the flame retardant, and the polytetrafluoroethylene micro powder is (2.2 - 2.8):1:0.8, preferably 2.5:1:0.8.

[0047] Kitchen appliances often inevitably come into contact with edible oil. The inventors have found that only through the action of the organically coated nano filler and the hollow multi-layer carbon microsphere / ionic liquid composite, the solid silicone composition has poor resistance to edible oil at high temperatures. To solve this technical problem, the inventors unexpectedly found that using polytetrafluoroethylene ultrafine powder with a particle size distribution of D50 < 5.0 μm and D90 < 10 μm and polytetrafluoroethylene ultrafine powder with a particle size distribution of D50 < 11 μm and D90 < 15 μm makes the solid silicone composition have more excellent resistance to edible oil at 300°C compared with polytetrafluoroethylene ultrafine powder with a single particle size distribution, and further improves its mechanical properties at 300°C. The inventors speculate that this is because polytetrafluoroethylene ultrafine powders with two different particle size distributions can not only better fill the tiny pores in the methyl vinyl silicone rubber, but also adsorb at different positions of the hollow multi-layer carbon microspheres to form a multi-level oil-repellent structure, thereby being able to avoid the penetration of edible oil and the thermal degradation of the solid silicone composition at 300°C; moreover, the inventors also found that when the mass ratio of the organically coated nano filler, the flame retardant, and the polytetrafluoroethylene micro powder is not within the range of (2.2 - 2.8):1:0.8, the mechanical properties and the resistance to edible oil of the solid silicone composition at 300°C decrease.

[0048] Preferably, the vulcanizing agent is selected from at least one of di-tert-butyl peroxide, benzoyl peroxide dichloride, dicumyl peroxide, and tert-butyl peroxybenzoate.

[0049] Preferably, the mold release agent is selected from at least one of stearic acid, zinc stearate, calcium stearate, magnesium stearate, and aluminum stearate.

[0050] The second aspect of the present invention provides a method for preparing the above-mentioned high-temperature resistant and flame-retardant solid silicone composition, which includes the following steps: First, place the raw methyl vinyl silicone rubber in an open mill for mixing, then add the organically coated nano-fillers, flame retardants, hydroxyl silicone oil, polytetrafluoroethylene ultrafine powder, and mold release agent for mixing, and finally add the vulcanizing agent for mixing to obtain the product.

[0051] Preferably, the method for preparing the high-temperature resistant and flame-retardant solid silicone composition includes the following steps: First, place the raw methyl vinyl silicone rubber in an open mill and mix it at 30 - 40 °C for 20 - 30 min, then add the organically coated nano-fillers, flame retardants, hydroxyl silicone oil, polytetrafluoroethylene ultrafine powder, and mold release agent and continue to mix for 5 - 15 min, let it stand for 12 h, and finally add the vulcanizing agent and mix evenly to obtain the product.

[0052] The third aspect of the present invention provides the application of the above-mentioned high-temperature resistant and flame-retardant solid silicone composition in the preparation of high-temperature resistant and flame-retardant sealing materials.

[0053] Compared with the prior art, the present invention has the following beneficial effects:

[0054] 1. The present invention creatively uses self-made organically coated nano-fillers, making the high-temperature resistant and flame-retardant solid silicone composition not only have excellent mechanical properties at a high temperature of 300 °C, but also have good flame retardancy and oil resistance to edible oil.

[0055] 2. The present invention creatively uses self-made hollow multi-layer carbon microsphere / ionic liquid composite, making the high-temperature resistant and flame-retardant solid silicone composition have excellent flame retardancy while also improving its high-temperature resistance.

[0056] 3. The present invention uses polytetrafluoroethylene ultrafine powder with a particle size distribution of D50 < 5.0 μm and D90 < 10 μm and polytetrafluoroethylene ultrafine powder with a particle size distribution of D50 < 11 μm and D90 < 15 μm, making the solid silicone composition have better oil resistance to edible oil at a high temperature of 300 °C, and further improving its mechanical properties at a high temperature of 300 °C.

[0057] 4. The inventor controls the mass ratio of the organically coated nano-fillers, flame retardants, and polytetrafluoroethylene micro-powder to be (2.2 - 2.8):1:0.8, avoiding the decline of the mechanical properties of the solid silicone composition at 300 °C and the oil resistance to edible oil performance at 300 °C. Specific Embodiments

[0058] For a clearer understanding of the technical features, objectives, and effects of the present invention, the specific implementation methods are now described in detail.

[0059] The present invention is further described below in conjunction with the embodiments, but the present invention is not limited to the following embodiments. The implementation conditions used in the embodiments can be further adjusted according to the different requirements of specific use, and the implementation conditions not indicated are conventional conditions in the industry. The technical features involved in each embodiment of the present invention can be combined with each other as long as they do not conflict with each other.

[0060] In the following examples and comparative examples, unless otherwise specified, all raw materials used were commercially available or prepared by conventional methods in the art.

[0061] Example 1

[0062] The high temperature resistant and flame retardant solid silicone composition comprises, by weight, 100 parts of methyl vinyl silicone rubber, 20 parts of organically coated nanofiller, 8 parts of flame retardant, 6 parts of hydroxy silicone oil, 5 parts of polytetrafluoroethylene ultrafine powder, 3 parts of vulcanizing agent and 0.5 parts of release agent.

[0063] The methyl vinyl silicone rubber raw rubber is vinyl-terminated methyl vinyl silicone rubber raw rubber, and the methyl vinyl silicone rubber raw rubber is a mixture of methyl vinyl silicone rubber raw rubber with a vinyl content of 0.21-0.24% and methyl vinyl silicone rubber raw rubber with a vinyl content of 4-5%, and the mass ratio of the two is 5:1.

[0064] The molecular weight of the methyl vinyl silicone rubber raw rubber with a vinyl content of 0.21-0.24% is 620,000±20,000 and is purchased from Dongjue Silicone Group Co., Ltd., model 110-3.

[0065] The molecular weight of the methyl vinyl silicone rubber raw rubber with a vinyl content of 4-5% is 67±20,000 and is purchased from Dongjue Silicone Group Co., Ltd., model 110-7.

[0066] The nano filler is nano oxide loaded with amorphous silicon dioxide and hollow glass micro beads; the mass ratio of the nano oxide loaded with amorphous silicon dioxide to the hollow glass micro beads is 2:1.

[0067] The hollow glass microspheres are hollow glass microspheres produced by Zhongke Huaxing New Materials Co., Ltd., model C100.

[0068] The nano-oxides are nano-alumina, nano-silicon dioxide and nano-cerium dioxide; the mass ratio of the nano-oxides is 15:15:0.3.

[0069] The particle size of the nano-alumina is 30 nm, and it was purchased from Beijing Zhongke Jinyan Technology Co., Ltd., model: DK-Al2O3-A30.

[0070] The particle size of the nano-silica is 15 nm, purchased from Zhongke Jinyan (Beijing) Technology Co., Ltd., model: DK-SiO2-15.

[0071] The particle size of the nano-ceria is 20 nm, purchased from Zhongke Jinyan (Beijing) Technology Co., Ltd., model: DK-SiO2-15.

[0072] The preparation method of the organically coated nano-filler includes the following steps:

[0073] Step 1: Add ammonia water to the nano-oxide solution, add tetraethyl orthosilicate (CAS No.: 78-10-4) at 35 °C, keep warm and stir for reaction for 10 h, and obtain the nano-oxide loaded with amorphous silica through centrifugation, washing and drying in sequence;

[0074] Step 2: Place the hollow glass microspheres in a sodium hydroxide solution, reflux and stir for reaction at 80 °C for 1.5 h, and obtain the pretreated hollow glass microspheres through washing and drying in sequence;

[0075] Step 3: Place the nano-oxide loaded with amorphous silica and the pretreated hollow glass microspheres in a reaction kettle, add sodium hydride, stir and heat up to 80 °C under nitrogen protection, slowly dropwise add 4-vinylbenzyl glycidyl ether (CAS No.: 113538-80-0), finish dropping within 1 h, continue to keep warm and stir for reaction for 7 h, and obtain the product after the reaction is cooled.

[0076] The preparation method of the nano-oxide solution is: disperse 50 mg of nano-oxide in 100 mL of ethanol aqueous solution; the ethanol aqueous solution is composed of ethanol and water with a mass ratio of 94:6.

[0077] The volume ratio of the nano-oxide aqueous solution, ammonia water and tetraethyl orthosilicate is 100:4:4.5; the mass fraction of the ammonia water is 25%.

[0078] The mass-volume ratio of the hollow glass microspheres and the sodium hydroxide solution is 0.03 g:1 mL; the concentration of the sodium hydroxide solution is 0.4 mol / L.

[0079] The addition amount of the sodium hydride is 0.4% of the total mass of the nano-oxide loaded with amorphous silica and the hollow glass microspheres.

[0080] The addition amount of the 4-vinylbenzyl glycidyl ether is 60% of the total mass of the nano-oxide loaded with amorphous silica and the hollow glass microspheres.

[0081] The flame retardant is a hollow multi-layer carbon microsphere / ionic liquid composite; the preparation method of the hollow multi-layer carbon microsphere / ionic liquid composite includes the following steps:

[0082] S1, mixing melamine solution and cyanuric acid solution evenly, reacting at 30°C for 25 minutes, centrifuging, washing and drying in sequence to obtain melamine cyanuric acid composite microspheres;

[0083] S2, mixing the melamine cyanuric acid composite microsphere solution and the dopamine solution evenly, stirring at 30°C for 30 minutes, adding Tris buffer, reacting at 30°C for 12 hours, centrifuging, washing and drying in sequence to obtain polydopamine-coated melamine cyanuric acid composite microspheres;

[0084] S3, keeping the polydopamine-coated melamine-cyanuric acid composite microspheres in an inert atmosphere at 450° C. for 2.5 h, and then keeping them at 800° C. for 2.5 h, to obtain hollow multilayer carbon microspheres;

[0085] S4. Place the hollow multilayer carbon microspheres in a vacuum environment, add ionic liquid dropwise, and wash and dry in sequence after the addition is completed.

[0086] The preparation method of the melamine solution is as follows: 0.5 g of melamine (CAS No.: 108-78-1) is dissolved in 18 mL of dimethyl sulfoxide (CAS No.: 67-68-5).

[0087] The preparation method of the cyanuric acid solution is as follows: 0.5 g of cyanuric acid (CAS No.: 108-80-5) is dissolved in 12 mL of dimethyl sulfoxide.

[0088] The volume ratio of the melamine solution to the cyanuric acid solution is 1.8:1.

[0089] The preparation method of the melamine cyanuric acid composite microsphere solution is as follows: 0.5 g of melamine cyanuric acid composite microsphere is dissolved in 100 mL of water.

[0090] The preparation method of the dopamine solution is as follows: 0.5 g of dopamine hydrochloride (CAS No.: 62-31-7) is dissolved in 100 mL of water.

[0091] The preparation method of the Tris buffer is as follows: 0.5 g of tris(hydroxymethyl)aminomethane (CAS No.: 77-86-1) is dissolved in 100 mL of water.

[0092] The volume ratio of the melamine cyanuric acid composite microsphere solution, the dopamine solution and the Tris buffer solution is 1:1:1.

[0093] The mass ratio of the hollow multilayer carbon microspheres to the ionic liquid is 1:35.

[0094] The ionic liquid is 1-ethyl acetate-3-methylimidazolium hexafluorophosphate, which was purchased from Xi'an Qiyue Biotechnology Co., Ltd.

[0095] The hydroxyl content in the hydroxyl silicone oil is 9 wt%, and the viscosity is 30 mm 2 / s. It is purchased from Zhejiang Zhenghe Silicon Materials Co., Ltd., grade: 207-30.

[0096] The polytetrafluoroethylene ultrafine powder includes polytetrafluoroethylene ultrafine powder with a particle size distribution of D50 < 5.0 μm and D90 < 10 μm and polytetrafluoroethylene ultrafine powder with a particle size distribution of D50 < 11 μm and D90 < 15 μm; the mass ratio of the two is 3:1; both are purchased from Fuzhou Taida New Materials Co., Ltd., and the models are TPD-505 and TPD-511 respectively.

[0097] The vulcanizing agent is di-tert-butyl peroxide (CAS No.: 110-05-4).

[0098] The mold release agent is magnesium stearate (CAS No.: 557-04-0).

[0099] The preparation method of the above high-temperature resistant and flame-retardant solid silicone composition includes the following steps: First, place the methyl vinyl silicone rubber raw rubber in an open mill and knead it at 35°C for 25 min, then add the organically coated nano-filler, flame retardant, hydroxyl silicone oil, polytetrafluoroethylene ultrafine powder, and mold release agent and continue to knead for 10 min, let it stand for 12 h, and finally add the vulcanizing agent and knead evenly to obtain.

[0100] Example 2

[0101] The difference from Example 1 is that for the high-temperature resistant and flame-retardant solid silicone composition, by mass, the raw materials include: 100 parts of methyl vinyl silicone rubber raw rubber, 30 parts of organically coated nano-filler, 12 parts of flame retardant, 10 parts of hydroxyl silicone oil, 10 parts of polytetrafluoroethylene ultrafine powder, 8 parts of vulcanizing agent, and 1.5 parts of mold release agent; the rest are the same.

[0102] The preparation method of the above high-temperature resistant and flame-retardant solid silicone composition is the same as that of Example 1.

[0103] Example 3

[0104] The difference from Example 1 is that for the high-temperature resistant and flame-retardant solid silicone composition, by mass, the raw materials include: 100 parts of methyl vinyl silicone rubber raw rubber, 25 parts of organically coated nano-filler, 10 parts of flame retardant, 8 parts of hydroxyl silicone oil, 8 parts of polytetrafluoroethylene ultrafine powder, 5 parts of vulcanizing agent, and 1 part of mold release agent; the rest are the same.

[0105] The preparation method of the above high-temperature resistant and flame-retardant solid silicone composition is the same as that of Example 1.

[0106] Comparative Example 1

[0107] The difference from Example 3 is that the organically coated nano-fillers are replaced with nano-fillers of the same mass; the rest are the same.

[0108] Comparative Example 2

[0109] The difference from Example 3 is that the hollow glass microspheres are replaced with nano-oxides loaded with amorphous silica of the same mass; the rest are the same.

[0110] Comparative Example 3

[0111] The difference from Example 3 is that the hollow glass microspheres are replaced with nano-ceria of the same mass; the rest are the same.

[0112] Comparative Example 4

[0113] The difference from Example 3 is that the hollow multi-layer carbon microsphere / ionic liquid composite is replaced with hollow multi-layer carbon microspheres of the same mass; the rest are the same.

[0114] Comparative Example 5

[0115] The difference from Example 3 is that the hollow multi-layer carbon microsphere / ionic liquid composite is replaced with ionic liquid of the same mass; the rest are the same.

[0116] Comparative Example 6

[0117] The difference from Example 3 is that the hollow multi-layer carbon microsphere / ionic liquid composite is replaced with a hollow carbon microsphere / ionic liquid composite of the same mass; the preparation method of the hollow carbon microsphere / ionic liquid composite includes the following steps:

[0118] S1. Mix the melamine solution and the cyanuric acid solution evenly, react at 30 °C for 25 min, and obtain melamine cyanurate composite microspheres through centrifugation, washing, and drying in sequence;

[0119] S3. Keep the melamine cyanurate composite microspheres in an inert atmosphere, first keep them at 450 °C for 2.5 h, and then keep them at 800 °C for 2.5 h to obtain hollow carbon microspheres;

[0120] S3. Place the hollow carbon microspheres in a vacuum environment, dropwise add ionic liquid, and after the addition is completed, wash and dry them in sequence to obtain; the rest are the same.

[0121] Comparative Example 7

[0122] The difference from Example 3 is that the polytetrafluoroethylene ultrafine powder with a particle size distribution of D50 < 11 μm and D90 < 15 μm is replaced with polytetrafluoroethylene ultrafine powder with a particle size distribution of D50 < 5.0 μm and D90 < 10 μm of the same mass; the rest are the same.

[0123] Comparative Example 8

[0124] The difference from Example 3 lies in that the mass ratio of the organically coated nano filler, flame retardant and polytetrafluoroethylene micro powder is 2:1.3:1, that is, for the high-temperature resistant and flame-retardant solid silicone composition, by mass, the raw materials include: 100 parts of methyl vinyl silicone rubber raw rubber, 20 parts of organically coated nano filler, 13 parts of flame retardant, 8 parts of hydroxyl silicone oil, 10 parts of polytetrafluoroethylene ultra-fine powder, 5 parts of vulcanizing agent, and 1 part of mold release agent; the rest are the same.

[0125] Performance test:

[0126] The high-temperature resistant and flame-retardant solid silicone compositions of Examples 1-3 and Comparative Examples 1-8 were respectively placed in a flat vulcanizing machine for vulcanization. Specifically: first, perform primary vulcanization: vulcanization temperature 120°C, vulcanization pressure 15 MPa, vulcanization time 30 min; then perform secondary vulcanization: vulcanization temperature 200°C, vulcanization time 3 h; perform the following performance tests on the vulcanized and molded samples:

[0127] 1. Tensile strength: Test standard: GB / T528-2009;

[0128] 2. Elongation at break: Test standard: GB / T528-2009;

[0129] 3. Flame retardancy: Test standard: UL94;

[0130] 4. High-temperature resistance: Test standard GB / T3512-2004;

[0131] 5. Edible oil resistance: Coat corn oil on the high-temperature resistant and flame-retardant solid silicone composition, and then test according to the standard GB / T3512-2004.

[0132] The results are shown in Table 1:

[0133] Table 1 Performance test results of the high-temperature resistant and flame-retardant solid silicone compositions of Examples 1-3 and Comparative Examples 1-8

[0134]

[0135] As can be seen from Table 1, the high-temperature resistant and flame-retardant solid silicone combinations of Examples 1-3 have excellent mechanical properties whether aged at 300°C for 8 days or aged at 300°C for 8 days after being coated with edible oil, and the flame retardancy level is V0;

[0136] Comparative Example 1: Replace the organically coated nano-fillers with nano-fillers of the same mass; Comparative Example 2: Replace the hollow glass microspheres with nano-oxides loaded with amorphous silica of the same mass; Comparative Example 3: Replace the hollow glass microspheres with nano-ceria of the same mass; that is, Comparative Examples 1-3 changed the composition of the organically coated nano-fillers. The mechanical properties of the obtained high-temperature resistant and flame-retardant solid silicone compositions decreased after aging at 300°C for 8 days and after applying edible oil and aging at 300°C for 8 days, and the flame retardancy levels of Comparative Examples 1-2 also decreased;

[0137] Comparative Example 4: Replace the hollow multi-layer carbon microsphere / ionic liquid composite with hollow multi-layer carbon microspheres of the same mass; Comparative Example 5: Replace the hollow multi-layer carbon microsphere / ionic liquid composite with ionic liquids of the same mass; Comparative Example 6: Replace the hollow multi-layer carbon microsphere / ionic liquid composite with hollow carbon microsphere / ionic liquid composites of the same mass; that is, Comparative Examples 4-6 changed the composition of the hollow multi-layer carbon microsphere / ionic liquid composite. The flame retardancy of the obtained high-temperature resistant and flame-retardant solid silicone compositions decreased significantly, and the mechanical properties also decreased after aging at 300°C for 8 days and after applying edible oil and aging at 300°C for 8 days;

[0138] Comparative Example 7: Replace the polytetrafluoroethylene ultrafine powder with a particle size distribution of D50 < 11 μm and D90 < 15 μm with polytetrafluoroethylene ultrafine powder with a particle size distribution of D50 < 5.0 μm and D90 < 10 μm of the same mass; the mechanical properties of the obtained high-temperature resistant and flame-retardant solid silicone composition decreased significantly after applying edible oil and aging at 300°C for 8 days; and the mechanical properties also decreased after aging at 300°C for 8 days;

[0139] In Comparative Example 8, the mass ratio of the organically coated nano-fillers, flame retardant, and polytetrafluoroethylene micro-powder was not within the range of (2.2 - 2.8):1:0.8. The mechanical properties of the high-temperature resistant and flame-retardant solid silicone composition decreased after aging at 300°C for 8 days and after applying edible oil and aging at 300°C for 8 days.

[0140] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, rather than a limitation on the protection scope of the present invention. Any simple modification or equivalent replacement of the technical solution of the present invention by those of ordinary skill in the art shall not depart from the essence and scope of the technical solution of the present invention.

Claims

1. A solid silicone composition that is heat-resistant and flame-retardant, characterized in that, By mass parts, the raw materials include: 100 parts of methyl vinyl silicone rubber raw rubber, 20 - 30 parts of organically coated nano - filler, 8 - 12 parts of flame retardant, 6 - 10 parts of hydroxyl silicone oil, 5 - 10 parts of polytetrafluoroethylene ultrafine powder, 3 - 8 parts of vulcanizing agent, and 0.5 - 1.5 parts of mold release agent; The preparation method of the organically coated nano - filler: Step 1: Add ammonia water to the nano - oxide solution, add tetraethyl orthosilicate at 30 - 40 °C, keep warm and stir - react for 8 - 12 h, and successively carry out centrifugation, washing and drying to obtain nano - oxide loaded with amorphous silica; Step 2: Place hollow glass microspheres in sodium hydroxide solution, reflux and stir - react at 70 - 90 °C for 1 - 2 h, and successively carry out washing and drying to obtain pretreated hollow glass microspheres; Step 3: Place the nano - oxide loaded with amorphous silica and the pretreated hollow glass microspheres in a reaction kettle, add sodium hydride, stir and heat up to 70 - 90 °C under nitrogen protection, slowly dropwise add 4 - vinylbenzyl glycidyl ether, finish dropping within 1 h, continue to keep warm and stir - react for 6 - 8 h, and cool down after the reaction ends to obtain; The mass ratio of the nano - oxide loaded with amorphous silica to the hollow glass microspheres is (1 - 3):(0.5 - 1.5); The preparation method of the flame retardant: S1: Mix the melamine solution and cyanuric acid solution evenly, react at 25 - 35 °C for 20 - 30 min, and successively carry out centrifugation, washing and drying to obtain melamine cyanurate composite microspheres; S2: Mix the melamine cyanurate composite microsphere solution and dopamine solution evenly, stir at 25 - 35 °C for 20 - 40 min, then add Tris buffer solution, react at 25 - 35 °C for 10 - 15 h, and successively carry out centrifugation, washing and drying to obtain polydopamine - coated melamine cyanurate composite microspheres; S3: Place the polydopamine - coated melamine cyanurate composite microspheres in an inert atmosphere, first keep warm at 400 - 500 °C for 2 - 3 h, then keep warm at 750 - 850 °C for 2 - 3 h to obtain hollow multi - layer carbon microspheres; S4: Place the hollow multi - layer carbon microspheres in a vacuum environment, dropwise add ionic liquid, and successively carry out washing and drying after dropping to obtain; The polytetrafluoroethylene ultrafine powder includes TPD - 505 and TPD - 511 of Fuzhou Taipuda New Materials Co., Ltd.; The mass ratio of the organically coated nano - filler, flame retardant and polytetrafluoroethylene micro - powder is (2.2 - 2.8):1:0.

8.

2. The high-temperature resistant and flame-retardant solid silicone composition according to claim 1, wherein, The methyl vinyl silicone rubber raw rubber is a mixture of methyl vinyl silicone rubber raw rubber with a vinyl content of 0.21 - 0.24% and methyl vinyl silicone rubber raw rubber with a vinyl content of 4 - 5%; the mass ratio of the two is (4 - 6):

1.

3. The high-temperature resistant and flame-retardant solid silicone composition according to claim 1, wherein The nano - oxide is nano - alumina, nano - silica and nano - cerium dioxide; the mass ratio of nano - alumina, nano - silica and nano - cerium dioxide is (10 - 20):(10 - 20):(0.2 - 0.4).

4. The high-temperature resistant and flame-retardant solid silicone composition according to claim 1, wherein The ionic liquid includes 1-ethyl acetate-3-methylimidazolium hexafluorophosphate and / or 1-ethyl acetate-3-methylimidazolium tetrafluoroborate.

5. A method for preparing the high-temperature resistant and flame-retardant solid silicone composition according to any one of claims 1 to 4, characterized in that, It includes the following steps: First, place the raw methyl vinyl silicone rubber in an open mill for mixing, then add the organically coated nano-fillers, flame retardants, hydroxyl silicone oil, polytetrafluoroethylene ultrafine powder, and mold release agent for mixing, and finally add the vulcanizing agent for mixing to obtain the product.

6. Use of the high-temperature resistant and flame retardant solid silicone composition according to any one of claims 1-4 in the preparation of high-temperature resistant and flame retardant sealing materials.

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