A ceramic flame-retardant silicone rubber and its preparation method

Abstract

The present application relates to the technical field of ceramic flame-retardant silicone rubber processing, and more specifically, to a ceramic flame-retardant silicone rubber and a preparation method thereof, which is prepared from the following raw materials in weight percentage: 50-60% silicone rubber, 4-8% hydroxy silicone oil, 3-6% boric acid, 10-15% ceramic reinforcing filler, 5-10% polyamide wax powder, 6-12% organosilicon-modified polyurethane resin, 1-2% vulcanizing agent, and the remainder being a flux; the flux is obtained by mixing glass powder, olivine powder, calcium fluoride and rare earth oxides. By adopting the above formula, the corrosion resistance and long-term stability of the ceramic flame-retardant silicone rubber under high temperature conditions are effectively improved, and the service life of the ceramic flame-retardant silicone rubber is extended.

Description

Technical Field

[0001] The present application relates to the technical field of ceramic flame-retardant silicone rubber processing, and more specifically, to a ceramic flame-retardant silicone rubber and a preparation method thereof. Background Art

[0002] Petrochemical production facilities often operate in high-temperature environments, such as heating furnaces and reactors. Therefore, the cables used must exhibit excellent heat resistance and flame retardancy. Ceramic silicone rubber cable, a new cable material that has demonstrated outstanding performance in these areas in recent years, is becoming the preferred choice in the petrochemical industry. Its unique performance advantage lies in its ability to maintain excellent electrical insulation and mechanical strength even in extremely high-temperature environments, effectively resisting performance degradation caused by thermal stress. Ceramic silicone rubber cable gradually transforms into a hard, ceramic-like substance at high temperatures. This process not only enhances the cable's fire resistance but also significantly improves its resistance to flame penetration, providing a valuable window of opportunity for safely shutting down petrochemical facilities in emergency situations.

[0003] However, ceramic silicone rubber cables also face the problem of accelerated aging due to the combined effects of prolonged high temperatures and chemical products. High temperatures accelerate the breakage and rearrangement of polymer chains within the cable, causing changes in the molecular structure and, in turn, affecting the cable's overall performance. Furthermore, corrosive chemicals used in petrochemical production, such as acids, alkalis, and salts, can corrode the cable, further exacerbating the aging process. This can cause the cable's surface to harden and crack, and even damage the internal insulation layer. This directly reduces the cable's high-temperature and flame-retardant properties, increasing the risk of electrical failure and fire. Summary of the Invention

[0004] In order to solve the problem of aging of ceramic silicone rubber caused by long-term use in high-temperature environment and corrosion of chemical products, the present application provides a ceramic flame-retardant silicone rubber and a preparation method thereof.

[0005] In a first aspect, the present application provides a ceramic flame-retardant silicone rubber, which adopts the following technical solution:

[0006] A ceramic flame-retardant silicone rubber is prepared from the following raw materials in the following weight percentages:

[0007] Silicone rubber 50-60%

[0008] Hydroxyl silicone oil 4-8%

[0009] Boric acid 3-6%

[0010] Ceramic reinforcing filler 10-15%

[0011] Polyamide wax powder 5-10%

[0012] Silicone modified polyurethane resin 6-12%

[0013] Vulcanizing agent 1-2%

[0014] The remaining amount is flux;

[0015] The flux is obtained by mixing glass powder, olivine powder, calcium fluoride and rare earth oxide.

[0016] By adopting the above technical solution, the corrosion resistance and long-term stability of the ceramic flame retardant silicone rubber under high temperature conditions are effectively improved, and the service life of the ceramic flame retardant silicone rubber is extended.

[0017] Among them, silicone modified polyurethane resin combines the advantages of silicone rubber and polyurethane, has higher chemical stability, the silicon-oxygen bond in its molecular structure is more stable than the carbon-carbon bond, and can resist the erosion of various chemicals. At the same time, silicone modified polyurethane resin has good compatibility with silicone rubber resin and is easier to process. In this application, silicone rubber and modified polyurethane resin are used in combination to form a more stable composite system, which improves the corrosion resistance and long-term high temperature resistance of ceramic flame retardant silicone rubber. At the same time, the synergistic effect of silicone rubber and hydroxyl silicone oil not only improves the flexibility of the cable, but also ensures that the cable can still maintain good elasticity at high temperatures, avoiding cracking or breakage caused by excessive hardening. Polyamide wax powder helps to improve the processing performance of the cable at high temperatures, and can reduce the accumulation of internal stress of the cable at high temperatures to a certain extent, thereby extending the service life of the cable in a high temperature environment.

[0018] Vulcanizing agents promote the formation of a stable cross-linked network between silicone rubber and silicone-modified polyurethane, thereby ensuring the strength and stability of the ceramicized flame-retardant silicone rubber. The ceramicized reinforcing filler, combined with silicone rubber and silicone-modified polyurethane, enables the ceramicized silicone rubber to maintain excellent mechanical strength, such as tensile strength, tear strength, and abrasion resistance, even at high temperatures. Furthermore, the ceramicized reinforcing filler chemically reacts with the silicone rubber at high temperatures, gradually transforming into a hard, ceramic-like substance, significantly improving the ceramicized silicone rubber's high-temperature resistance and fire resistance. Boric acid accelerates the ceramicization of the silicone rubber at high temperatures, forming a hard ceramic layer that increases the cable's fire resistance and resistance to flame penetration.

[0019] A fluxing agent, comprised of glass powder, olivine powder, calcium fluoride, and rare earth oxides, plays a key role in the ceramicization process, promoting the ceramicization reaction and improving the density and strength of the ceramicized product. This ensures the stability of the ceramicized silicone rubber under high-temperature conditions and further enhances the mechanical and flame-retardant properties of the cable. The glass powder and calcium fluoride both act as fluxing agents, lowering the silicone rubber's sintering temperature and accelerating the sintering process. The rare earth oxides promote the fluxing of the glass powder and calcium fluoride, resulting in more complete and uniform sintering. The glass powder and olivine powder act as reinforcing fillers, increasing the flexural strength and hardness of the sintered product.

[0020] Preferably, the weight ratio of the glass powder, the olivine powder, the calcium fluoride and the rare earth oxide is (4-6): (2-4): (6-10): 3.

[0021] By adopting the above technical solution, the dosage of glass powder, olivine powder, calcium fluoride and rare earth oxide is optimized, and the fluxing effect of the flux is further improved, the sintering temperature can be reduced, the sintering process can be accelerated, and the mechanical properties and density of the sintered product can be improved, thereby improving the long-term stability of the ceramic flame-retardant silicone rubber under high temperature conditions and extending the service life of the ceramic flame-retardant silicone rubber.

[0022] Preferably, the rare earth oxide includes at least one of bismuth oxide, lanthanum oxide, molybdenum trioxide, rubidium oxide, europium oxide, samarium oxide, erbium oxide, scandium oxide, yttrium oxide and thulium oxide.

[0023] By adopting the above technical solution, the types of rare earth oxides are optimized, the fluxing effect of glass powder and calcium fluoride is further promoted, the sintering is made more complete and uniform, and the flame retardancy of ceramic silicone rubber and its stability in use under high temperature conditions are improved.

[0024] Preferably, the organosilicon-modified polyurethane resin is prepared by the following preparation method:

[0025] 1) mixing 1 mol of hydroxy-terminated polydimethylsiloxane, 1.1-1.2 mol of vinyltrimethoxysilane, 0.01 mol of a catalyst, and solvent 1 to obtain a mixture;

[0026] 2) Solvent 2 is mixed with 0.8-0.9 mol of a polyurethane oligomer, stirred and heated to 100-110° C., and the mixture is added dropwise. After the addition is complete, the mixture is kept warm for 6-9 hours. When the -NCO content is detected to be less than 1%, vacuum distillation is performed to recover the solvent to obtain a silicone-modified polyurethane resin.

[0027] By adopting the above technical solution, a silicone-modified polyester resin is prepared, which can improve the strength, corrosion resistance, and high-temperature stability of ceramic silicone rubber. In step 1), the terminal hydroxyl polydimethylsiloxane and vinyl trimethoxysilane react with a catalyst to introduce vinyl groups into the siloxane chain, which is conducive to reaction with polyurethane oligomers. In step S2), the isocyanate groups in the polyurethane oligomer react with the hydroxyl groups in the silicone mixture to produce a silicone-modified polyurethane resin. The silicone-modified polyurethane resin introduced with the terminal hydroxyl polydimethylsiloxane and vinyl trimethoxysilane has excellent corrosion resistance and high-temperature resistance.

[0028] Preferably, the molecular formula of the polyurethane oligomer is (C15H10N2O2.C3H8O2.C3H6O.C2H4O)X, where X=20-80.

[0029] By adopting the above technical solution and optimizing the molecular formula of the polyurethane oligomer, the reaction can be accelerated. At the same time, an appropriate degree of polymerization can improve the heat resistance and corrosion resistance of the silicone-modified polyurethane. Excessively high X values ​​in polyurethane oligomers can increase the brittleness of the silicone-modified polyurethane and affect its processing properties.

[0030] Preferably, the molar mass of the hydroxyl-terminated polydimethylsiloxane is 400-2000, and the hydroxyl value is 1.7-8.5%.

[0031] By adopting the above technical solution, the molar mass and hydroxyl value of the terminal hydroxyl polydimethylsiloxane are optimized, the reaction between the terminal hydroxyl polydimethylsiloxane and the polyurethane oligomer is further promoted, and at the same time, the molecular chain of the silicone-modified polyurethane resin is ensured not to be too long, which is conducive to the subsequent increase in the cross-linking density, thereby improving the corrosion resistance and high temperature resistance of the ceramic silicone rubber.

[0032] Preferably, the silicone rubber is obtained by mixing methyl vinyl silicone rubber and methyl phenyl vinyl silicone rubber in a weight ratio of (8-10):3.

[0033] By employing the above technical solution, the type of silicone rubber is optimized, improving the high-temperature and corrosion resistance of ceramic silicone rubber. Specifically, the presence of phenyl groups in methylphenylvinyl silicone rubber further enhances the high-temperature resistance of ceramic silicone rubber. However, excessive amounts of methylphenylvinyl silicone rubber should be avoided, as this can increase the hardness and reduce the elasticity of the ceramic silicone rubber, making it difficult to use.

[0034] Preferably, the average particle size of the ceramic reinforcing filler is 100-500 nm.

[0035] By adopting the above technical solution, the average particle size of the ceramic reinforcing filler is optimized, the bonding force between the ceramic reinforcing filler and silicone rubber and silicone-modified silicone rubber is improved, and the tensile strength, thermal stability and flame retardancy of the ceramic silicone rubber are improved.

[0036] In a second aspect, the present application provides a method for preparing ceramic flame-retardant silicone rubber, which adopts the following technical solution:

[0037] A method for preparing ceramic flame-retardant silicone rubber comprises the following steps:

[0038] S1, mixing silicone rubber, hydroxy silicone oil, boric acid, ceramic reinforcing filler, polyamide wax powder, organosilicon-modified polyurethane resin, vulcanizing agent and flux to obtain a mixture;

[0039] S2. vulcanizing the mixture to obtain ceramic flame-retardant silicone rubber.

[0040] By adopting the above technical solution, various raw materials are fully mixed and vulcanized to obtain ceramic silicone rubber with good corrosion resistance, long-term use under high temperature conditions, good strength and good flame retardancy.

[0041] Preferably, in step S2, the vulcanization includes a first vulcanization and a second vulcanization performed sequentially, wherein the first vulcanization temperature is 190-210°C, the time is 4-7 minutes, and the pressure is 8-10 MPa; the second vulcanization temperature is 130-150°C, the time is 60-80 minutes, and the pressure is 10-12 MPa.

[0042] By adopting the above technical solution, the silicone rubber and silicone-modified polyurethane can be fully cross-linked. The two vulcanization processes make the cross-linking structure inside the ceramic flame-retardant silicone rubber more perfect and increase the cross-linking density, which helps to improve the strength, long-term high temperature resistance and corrosion resistance of the ceramic flame-retardant silicone rubber.

[0043] In summary, this application has the following beneficial effects:

[0044] 1. Enhanced high-temperature resistance and durability: In this application, by combining silicone rubber, hydroxy silicone oil, boric acid, ceramic reinforcing filler, polyamide wax powder, silicone-modified polyurethane resin, vulcanizing agent and flux, the long-term high-temperature resistance and flame retardant properties of ceramic silicone rubber can be significantly improved.

[0045] 2. Optimize chemical corrosion resistance: The addition of silicone modified polyurethane resin enhances the resistance of silicone rubber to corrosive chemicals such as acids, alkalis, and salts, reducing the accelerated aging of cables caused by chemical corrosion in petrochemical environments.

[0046] 3. Excellent mechanical properties: The addition of hydroxyl silicone oil and ceramic reinforcing fillers improves the mechanical strength of ceramic silicone rubber, enables ceramic silicone rubber to maintain better structural integrity in harsh environments, and reduces performance degradation caused by physical damage. DETAILED DESCRIPTION

[0047] Example

[0048] The silicone rubber used in Examples 1-3 is methyl vinyl silicone rubber.

[0049] Example 1

[0050] A ceramic flame-retardant silicone rubber is prepared by the following method:

[0051] S1, 500g of silicone rubber, 40g of hydroxy silicone oil, 30g of boric acid, 150g of ceramic reinforcing filler (fumed silica), 100g of polyamide wax powder, 120g of silicone-modified polyurethane resin, 10g of vulcanizing agent (platinum vulcanizing agent, SK-P030) and 50g of flux were mixed to obtain a mixture;

[0052] S2. vulcanizing the mixture to obtain ceramic flame-retardant silicone rubber.

[0053] In step S2, the vulcanization includes a first vulcanization and a second vulcanization performed sequentially. The first vulcanization temperature is 190° C., the time is 4 minutes, and the pressure is 8 MPa; the second vulcanization temperature is 130° C., the time is 60 minutes, and the pressure is 10 MPa.

[0054] The flux is obtained by mixing glass powder, olivine powder, calcium fluoride and rare earth oxide (lanthanum oxide) in a weight ratio of 4:2:6:3.

[0055] The molecular weight of methyl vinyl silicone rubber is 150,000 and the vinyl molar content is 0.2%.

[0056] Silicone-modified polyurethane resin was purchased from Chengdu Hexingxing New Material Technology Co., Ltd., model number 9651.

[0057] The hydrogen content of hydroxy silicone oil is 0.8% and the molecular weight is 10,000.

[0058] Polyamide wax powder was purchased from Shanghai Deyude Trading Co., Ltd., model number 6650.

[0059] The difference between Example 2-3 and Example 1 is that the types, amounts and parameters of some raw materials used in preparing the ceramic flame-retardant silicone rubber are different. The specific differences are shown in Table 1:

[0060] Table 1 Types, amounts and parameters of raw materials used in preparing ceramic flame-retardant silicone rubber in Examples 1-3

[0061]

[0062]

[0063] In Example 2, the flux is obtained by mixing glass powder, olivine powder, calcium fluoride and rare earth oxide (lanthanum oxide) in a weight ratio of 5:3:8:3.

[0064] In Example 3, the flux is obtained by mixing glass powder, olivine powder, calcium fluoride and rare earth oxide (lanthanum oxide) in a weight ratio of 6:4:10:3.

[0065] Example 4

[0066] A ceramic flame-retardant silicone rubber. The difference between this embodiment and the embodiment is that the rare earth oxide is obtained by mixing bismuth oxide and lanthanum oxide in a weight ratio of 1:1.

[0067] Example 5

[0068] A ceramic flame-retardant silicone rubber. This embodiment differs from Embodiment 1 in that the rare earth oxide is obtained by mixing molybdenum trioxide and rubidium oxide in a weight ratio of 1:1.

[0069] Example 6

[0070] A ceramic flame-retardant silicone rubber. This embodiment differs from Example 1 in that the organosilicon-modified polyurethane resin is prepared by the following preparation method:

[0071] 1) mixing 1 mol of hydroxy-terminated polydimethylsiloxane, 1.1 mol of vinyltrimethoxysilane, 0.01 mol of a catalyst (dibutyltin dilaurate), and 200 ml of solvent 1 (toluene) to obtain a mixture;

[0072] 2) 100 ml of solvent 2 (toluene) was mixed with 0.8 mol of polyurethane oligomer, stirred and heated to 100° C., and the mixture was added dropwise. After the addition was complete, the mixture was kept warm for 6 hours. When the -NCO content was detected to be less than 1%, vacuum distillation was performed and the solvent was recovered to obtain a silicone-modified polyurethane resin.

[0073] The molecular formula of the polyurethane oligomer is (C15H10N2O2.C3H8O2.C3H6O.C2H4O)X, where X=20.

[0074] The molar mass of the hydroxyl-terminated polydimethylsiloxane is 400, and the hydroxyl value is 1.7%.

[0075] Example 7

[0076] A ceramic flame-retardant silicone rubber. This embodiment differs from Example 1 in that the organosilicon-modified polyurethane resin is prepared by the following preparation method:

[0077] 1) mixing 1 mol of hydroxy-terminated polydimethylsiloxane, 1.2 mol of vinyltrimethoxysilane, 0.01 mol of a catalyst (dibutyltin dilaurate), and 200 ml of solvent 1 (toluene) to obtain a mixture;

[0078] 2) 100 ml of solvent 2 (toluene) was mixed with 0.9 mol of polyurethane oligomer, stirred and heated to 110° C., and the mixture was added dropwise. After the addition was complete, the mixture was kept warm for 9 hours. When the -NCO content was detected to be less than 1%, vacuum distillation was performed and the solvent was recovered to obtain a silicone-modified polyurethane resin.

[0079] The molecular formula of the polyurethane oligomer is (C15H10N2O2.C3H8O2.C3H6O.C2H4O)X, where X=80.

[0080] The molar mass of the hydroxyl-terminated polydimethylsiloxane is 2000, and the hydroxyl value is 8.5%.

[0081] Example 8

[0082] A ceramic flame-retardant silicone rubber. The difference between this embodiment and embodiment 1 is that the silicone rubber is obtained by mixing methyl vinyl silicone rubber and methyl phenyl silicone rubber in a weight ratio of 8:3.

[0083] Methylphenyl vinyl silicone rubber, molecular weight is 150,000, phenyl molar content is 8%, vinyl molar content is 0.5%.

[0084] Example 9

[0085] A ceramic flame-retardant silicone rubber. The difference between this embodiment and embodiment 7 is that the silicone rubber is obtained by mixing methyl vinyl silicone rubber and methyl phenyl silicone rubber in a weight ratio of 10:3.

[0086] Methylphenyl vinyl silicone rubber, molecular weight is 200,000, phenyl molar content is 11%, vinyl molar content is 0.9%.

[0087] Example 10

[0088] A ceramic flame-retardant silicone rubber. This embodiment differs from Embodiment 1 in that the average particle size of the ceramic reinforcing filler is 50-100 nm.

[0089] Example 11

[0090] A ceramic flame-retardant silicone rubber. This embodiment differs from Embodiment 1 in that the average particle size of the ceramic reinforcing filler is 500-600 nm.

[0091] Comparative Example

[0092] Comparative Example 1

[0093] A ceramic flame-retardant silicone rubber. This embodiment differs from Embodiment 1 in that talcum powder is used instead of flux.

[0094] Comparative Example 2

[0095] A ceramic flame-retardant silicone rubber. This embodiment differs from Embodiment 1 in that the flux is entirely glass powder.

[0096] Comparative Example 3

[0097] A ceramic flame-retardant silicone rubber. This embodiment differs from Embodiment 1 in that the flux is entirely olivine powder.

[0098] Comparative Example 4

[0099] A ceramic flame-retardant silicone rubber. This embodiment differs from Embodiment 1 in that the flux is entirely calcium fluoride.

[0100] Comparative Example 5

[0101] A ceramic flame-retardant silicone rubber. This embodiment differs from Embodiment 1 in that the flux is entirely lanthanum oxide.

[0102] Comparative Example 6

[0103] A ceramic flame-retardant silicone rubber. This embodiment differs from Embodiment 1 in that the flux is obtained by mixing glass powder and olivine powder in a weight ratio of 4:11.

[0104] Comparative Example 7

[0105] A ceramic flame-retardant silicone rubber. This embodiment differs from Embodiment 1 in that the flux is obtained by mixing glass powder and calcium fluoride in a weight ratio of 4:11.

[0106] Comparative Example 8

[0107] A ceramic flame-retardant silicone rubber. This embodiment differs from Embodiment 1 in that the flux is obtained by mixing glass powder and lanthanum oxide in a weight ratio of 4:11.

[0108] Comparative Example 9

[0109] A ceramic flame-retardant silicone rubber. This embodiment differs from Embodiment 1 in that the flux is obtained by mixing glass powder, olivine powder, and lanthanum oxide in a weight ratio of 4:2:9.

[0110] Comparative Example 10

[0111] A ceramic flame-retardant silicone rubber. This embodiment differs from Embodiment 1 in that the flux is obtained by mixing olivine powder, calcium fluoride, and lanthanum oxide in a weight ratio of 2:6:7.

[0112] Comparative Example 11

[0113] A ceramic flame-retardant silicone rubber. This embodiment differs from Embodiment 1 in that polyurethane resin is used instead of silicone-modified polyurethane resin.

[0114] Comparative Example 12

[0115] A ceramic flame-retardant silicone rubber. This embodiment differs from Embodiment 1 in that phosphoric acid is used instead of boric acid.

[0116] Detection method / test method

[0117] Corrosion resistance test: First, refer to GB / T528-2009 to measure the tensile strength of the ceramic flame-retardant silicone rubber prepared in Examples 1-11 and Comparative Examples 1-12, then soak them in oil at a temperature of 200°C for 5 hours, then soak them in a hydrochloric acid solution at a temperature of 50°C and a mass fraction of 15% for 5 hours, and then soak them in a sodium hydroxide solution at a temperature of 50°C and a mass fraction of 20% for 5 hours. The cycle was repeated 100 times, and the strength was measured again.

[0118] High-temperature resistance testing: The ceramic flame-retardant silicone rubber prepared in Examples 1-11 and Comparative Examples 1-12 was placed in a muffle furnace and heated to 900°C and 1200°C, respectively, for 24 hours at a heating rate of 15 min / °C. The volume change rate and compressive strength of the sintered products were calculated. A smaller volume change rate indicates greater stability of the ceramic flame-retardant silicone rubber under high-temperature conditions. A higher compressive strength indicates that the sintered product maintains good stability and load-bearing capacity under compressive loads; otherwise, deformation or failure may occur.

[0119] Flame retardant grade: Tested in accordance with GB / T10707-2008. Test data are shown in Table 2:

[0120] Table 2 Experimental data of Examples 1-11 and Comparative Examples 1-12

[0121]

[0122]

[0123] It can be seen from Examples 1-11 and Comparative Examples 1-12 in combination with Table 2 that the ceramic flame-retardant silicone rubber prepared by the formula in this application has good tensile strength, corrosion resistance, stability in use under high temperature conditions and flame retardancy.

[0124] Comparing Example 1 with Comparative Example 1, no flame retardant was used in Comparative Example 1, and the tensile strength of Comparative Example 1 was lower than that of Example 1; the volume change rate at 900°C and 1200°C was significantly greater than that of Example 1; the compressive strength at 900°C and 1200°C was significantly lower than that of Example 1; and the flame retardant grade was also lower than that of Example 1, indicating that the addition of a flux in this application is beneficial to improving the tensile strength, corrosion resistance, stability in use under high temperature conditions, and flame retardancy of the ceramicized flame retardant silicone rubber.

[0125] Comparing Example 1 with Comparative Examples 2-10, the tensile strength of Comparative Example 2-10 is lower than that of Example 1; the volume change rate at 900°C and 1200°C is significantly greater than that of Example 1; and the compressive strength at 900°C and 1200°C is significantly less than that of Example 1. This indicates that in the present application, by mixing glass powder, olivine powder, calcium fluoride and rare earth oxide to prepare a flux, which is then used to prepare ceramic silicone rubber, it is beneficial to improve the tensile strength, corrosion resistance and stability of ceramic flame retardant silicone rubber under high temperature conditions.

[0126] Comparing Example 1 with Comparative Example 11, the tensile strength of Comparative Example 11 is lower than that of Example 1; the volume change rate at 900°C and 1200°C is significantly greater than that of Example 1; and the compressive strength at 900°C and 1200°C is significantly less than that of Example 1. This indicates that in this application, by using silicone-modified polyurethane to prepare ceramic silicone rubber, it is beneficial to improve the tensile strength, corrosion resistance and stability of ceramic flame-retardant silicone rubber under high temperature conditions.

[0127] Comparing Example 1 with Comparative Example 12, the tensile strength in Comparative Example 12 is lower than that in Example 1; the volume change rate at 900°C and 1200°C is significantly greater than that in Example 1; and the compressive strength at 900°C and 1200°C is significantly less than that in Example 1. This indicates that in this application, by using silicone-modified polyurethane to prepare ceramic silicone rubber, it is beneficial to improve the tensile strength, corrosion resistance and stability of ceramic flame-retardant silicone rubber under high temperature conditions.

[0128] Comparing Example 1 with Examples 4-5, the volume change rate of Example 4-5 at 900°C and 1200°C is significantly smaller than that of Example 1; the compressive strength at 900°C and 1200°C is significantly greater than that of Example 1, indicating that optimizing the type of rare earth oxides is beneficial to improving the stability of ceramicized flame-retardant silicone rubber under high temperature conditions.

[0129] Comparing Example 1 with Example 6-7, the tensile strength of Example 6-7 is higher than that of Example 1, and the change rate of tensile strength is small after the corrosion resistance test; the volume change rate of Example 6-7 at 900°C and 1200°C is significantly smaller than that of Example 1; the compressive strength at 900°C and 1200°C is significantly greater than that of Example 1, indicating that the silicone-modified polyester resin prepared by this application is beneficial to improving the tensile strength, corrosion resistance and stability of ceramic flame-retardant silicone rubber under high temperature conditions.

[0130] Comparing Example 1 with Example 8, the tensile strength of Example 8 is higher than that of Example 1, and after the corrosion resistance test, the change rate of the tensile strength is small; the volume change rate of Example 8 at 900°C and 1200°C is smaller than that of Example 1; the compressive strength at 900°C and 1200°C is greater than that of Example 1;

[0131] Compared with Example 7, Example 9 has a higher tensile strength than Example 7, and after the corrosion resistance test, the change rate of tensile strength is small; the volume change rate of Example 9 at 900°C and 1200°C is smaller than that of Example 7; the compressive strength at 900°C and 1200°C is greater than that of Example 7;

[0132] It can be seen from Examples 1 and 8, 4 and 7 that preparing ceramic silicone rubber by using methyl vinyl silicone rubber and methyl phenyl silicone rubber together is beneficial to improving the tensile strength, corrosion resistance and stability of ceramic flame retardant silicone rubber under high temperature conditions.

[0133] Comparing Example 1 with Example 10-11, the tensile strength of Example 10-11 is lower than that of Example 1; the volume change rate of Example 10-11 at 900°C and 1200°C is greater than that of Example 1; and the compressive strength at 900°C and 1200°C is less than that of Example 1, indicating that optimizing the average particle size of the ceramic reinforcing filler is beneficial to improving the tensile strength and stability of the ceramic flame retardant silicone rubber under high temperature conditions.

[0134] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A ceramic flame retardant silicone rubber, characterized in that: Prepared from the following raw materials in weight percentage: Silicone rubber 50-60% Hydroxyl silicone oil 4-8% Boric acid 3-6% Ceramic reinforcing filler 10-15% Polyamide wax powder 5-10% Silicone modified polyurethane resin 6-12% Vulcanizing agent 1-2% The remaining amount is flux and the flux dosage is not 0; The flux is obtained by mixing glass powder, olivine powder, calcium fluoride and rare earth oxide; The weight ratio of the glass powder, the olivine powder, the calcium fluoride and the rare earth oxide is 4:2:6:3; The rare earth oxide includes at least one of bismuth oxide, lanthanum oxide, europium oxide, samarium oxide, erbium oxide, scandium oxide, yttrium oxide and thulium oxide; The organosilicon-modified polyurethane resin is prepared by the following preparation method: 1) mixing 1 mol of hydroxy-terminated polydimethylsiloxane, 1.2 mol of vinyltrimethoxysilane, 0.01 mol of catalyst dibutyltin dilaurate, and 200 mL of toluene to obtain a mixture; 2) 100 ml of toluene and 0.9 mol of polyurethane oligomer were mixed, stirred, and heated to 110° C. The mixture was then added dropwise. After the addition was complete, the mixture was kept warm for 9 hours. When the -NCO content was detected to be less than 1%, vacuum distillation was performed and the solvent was recovered to obtain a silicone-modified polyurethane resin. The molecular formula of the polyurethane oligomer is (C 15 H 10 N2O2.C3H8O2.C3H6O.C2H4O)X, X=80; The molar mass of the hydroxyl-terminated polydimethylsiloxane is 2000, and the hydroxyl value is 1.7%; The silicone rubber is methyl vinyl silicone rubber with a molecular weight of 150,000 and a vinyl molar content of 0.2%; The average particle size of the ceramic reinforcing filler is 100-500 nm.

2. A method for preparing the ceramic flame-retardant silicone rubber according to claim 1, characterized in that: The method comprises the following preparation steps: S1, mixing silicone rubber, hydroxy silicone oil, boric acid, ceramic reinforcing filler, polyamide wax powder, organosilicon-modified polyurethane resin, vulcanizing agent and cosolvent to obtain a mixture; S2, vulcanizing the mixture to obtain ceramic flame retardant silicone rubber; In step S2, the vulcanization includes a first vulcanization and a second vulcanization performed sequentially. The first vulcanization temperature is 190-210°C, the time is 4-7 minutes, and the pressure is 8-10 MPa; the second vulcanization temperature is 130-150°C, the time is 60-80 minutes, and the pressure is 10-12 MPa.

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