Fireproof and flame-retardant ceramicized silicone rubber and preparation method thereof

Abstract

The application relates to the technical field of high polymer materials, and discloses a fireproof and flame-retardant ceramifiable silicone rubber and a preparation method thereof. The fireproof and flame-retardant ceramifiable silicone rubber is prepared from the following components in parts by mass: 100 parts of silicone rubber, 5-20 parts of fumed white carbon black, 10-65 parts of modified flame retardant, 20-50 parts of ceramic powder, 5-20 parts of fluxing agent, 0.5-2 parts of vulcanizing agent and 1-7 parts of coupling agent; the raw material of the modified flame retardant comprises butyl acrylate-styrene sodium sulfonate-vinyl triethoxysilane copolymer and inorganic flame retardant. Through the technical scheme, the problem that the inorganic flame retardant and the silicone rubber have poor compatibility in the related art, leading to poor flame-retardant effect and mechanical property of the ceramifiable silicone rubber, is solved.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, specifically to a fire-retardant ceramicized silicone rubber and its preparation method. Background Technology

[0002] Silicone rubber is an organic polymer that has attracted widespread attention due to its high thermal stability, excellent fire resistance, and electrical insulation properties, and is widely used in aerospace, electronic circuits, medical and health, machinery industry, and various aspects of daily life. However, the flammability of silicone rubber severely restricts its further application in fields with high flame retardant requirements. Although the SiO2 ash produced after the combustion of ordinary silicone rubber can act as a barrier layer, it contains many pores, is brittle, has almost no mechanical strength, and is prone to expansion. Therefore, a dense ceramic layer cannot be formed solely from the ash.

[0003] In recent decades, researchers have successfully developed ceramicizable silicone rubber composite materials. These excellent fire-resistant materials have the same properties as ordinary polymers at room temperature. When exposed to high temperatures and ignited, they undergo a ceramicization reaction and transform into hard, self-supporting ceramic products. These ceramic products have certain impact resistance and can withstand the erosion of open flames at 1000°C, thus maintaining the integrity of the product.

[0004] Currently, the ceramic-forming system of ceramicized silicone rubber mainly includes flame retardants, fluxes, and ceramicizing powder. In order to achieve satisfactory ceramic-forming and flame-retardant effects during the preparation of ceramicized silicone rubber, a large amount of inorganic flame retardant is added to the system. However, with the increase in the amount of inorganic flame retardant in the system, due to its poor compatibility with silicone rubber, it is prone to agglomeration when mixed with silicone rubber, ultimately resulting in poor flame-retardant effect and mechanical properties of the prepared ceramicized silicone rubber. Summary of the Invention

[0005] This invention proposes a fire-retardant ceramicized silicone rubber and its preparation method, which solves the problem in related technologies that the poor compatibility between inorganic flame retardants and silicone rubber leads to poor flame retardant effect and mechanical properties of ceramicized silicone rubber.

[0006] The technical solution of the present invention is as follows:

[0007] A fire-retardant ceramicized silicone rubber comprises the following components in parts by weight: 100 parts silicone rubber, 5-20 parts fumed silica, 10-65 parts modified flame retardant, 20-50 parts ceramic powder, 5-20 parts flux, 0.5-2 parts vulcanizing agent, and 1-7 parts coupling agent. The modified flame retardant comprises butyl acrylate-sodium styrene sulfonate-vinyltriethoxysilane copolymer and inorganic flame retardant.

[0008] Silicone rubber is a special rubber whose main chain contains silicon and oxygen atoms. Using silicone rubber as a base material not only provides the material with good high-temperature and low-temperature resistance, but also excellent electrical insulation. In this invention, the silicone rubber can be any one or more conventional silicone rubbers in the art, such as dimethyl silicone rubber, methyl vinyl silicone rubber, methyl phenyl silicone rubber, methyl phenyl vinyl silicone rubber, etc. Methyl vinyl silicone rubber is preferred.

[0009] As a further technical solution, the specific surface area of ​​the fumed silica is 200~400 m² / g. 2 / g, for example, could be 200m 2 / g、250m 2 / g、300m 2 / g, 350m 2 / g or 400m 2 / g, but not limited to the listed values; other unlisted values ​​within this range also apply, preferably 200~300m. 2 / g, more preferably 250m 2 / g.

[0010] As a further technical solution, the mass ratio of the butyl acrylate-sodium styrene sulfonate-vinyltriethoxysilane copolymer to the inorganic flame retardant is 0.01~0.1:1, for example, it can be 0.01:1, 0.02:1, 0.03:1, 0.04:1, 0.05:1, 0.06:1, 0.07:1, 0.08:1, 0.09:1 or 0.1:1, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable, preferably 0.05:1.

[0011] As a further technical solution, the preparation method of the butyl acrylate-sodium styrene sulfonate-vinyltriethoxysilane copolymer includes the following steps:

[0012] After mixing butyl acrylate, vinyltriethoxysilane, and sodium styrene sulfonate with a solvent, the mixture is heated to 50-60°C and stirred for 5-10 minutes. A mixed solution of initiator and chain transfer agent is then added and reacted at 65-75°C for 1-1.5 hours. After the reaction is completed, the mixture is cooled and the solvent is removed to obtain a butyl acrylate-sodium styrene sulfonate-vinyltriethoxysilane copolymer.

[0013]

[0014] As a further technical solution, the mixed solution of the initiator and chain transfer agent is composed of azobisisobutyronitrile, dodecathiol, and N,N-dimethylformamide.

[0015] As a further technical solution, the mass ratio of azobisisobutyronitrile, dodecathiol, and N,N-dimethylformamide is 6:1:25.

[0016] As a further technical solution, the mass ratio of butyl acrylate, vinyltriethoxysilane and sodium styrene sulfonate is 3.99~5.69:3.17~4.94:1.07~1.14, and the preferred mass ratio is 3.99:4.94:1.07~5.69:3.17:1.14.

[0017] As a further technical solution, the preparation method of the modified flame retardant includes the following steps:

[0018] S1. After mixing the inorganic flame retardant, butyl acrylate-sodium styrene sulfonate-vinyltriethoxysilane copolymer and water, the mixture is milled and filtered to obtain the pretreated flame retardant.

[0019] S2. Extract the pretreated flame retardant and dry it to obtain a modified flame retardant.

[0020] As a further technical solution, the mass ratio of the inorganic flame retardant, butyl acrylate-sodium styrene sulfonate-vinyltriethoxysilane copolymer, and water is 1:0.05:2.5 to 1:0.1:5, for example, it can be 1:0.05:2.5, 1:0.05:3.5, 1:0.05:4.5, 1:0.05:5, 1:0.1:2.5, 1:0.1:3.5, 1:0.1:4.5, 1:0.1:5, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable, preferably 1:0.05:2.5.

[0021] As a further technical solution, the grinding time is 20-40 minutes.

[0022] As a further technical solution, the extraction specifically involves using ethanol as a solvent and performing Soxhlet extraction at 50-60℃ for 12-15 hours.

[0023] As a further technical solution, in step S2, the dried material is ball-milled to a particle size of 5~10μm.

[0024] As a further technical solution, the inorganic flame retardant includes one or more of magnesium hydroxide, aluminum hydroxide, and zinc borate.

[0025] Inorganic flame retardants possess advantages such as high stability, low volatility, low smoke toxicity, and low cost. Among them, aluminum hydroxide is non-toxic and non-corrosive; magnesium hydroxide has better thermal stability than aluminum hydroxide, and synthetic materials with added magnesium hydroxide can withstand higher processing temperatures; zinc borate is a multifunctional additive that, in addition to its flame-retardant and smoke-suppressing properties, also prevents molten dripping. The inorganic flame retardant in this invention can be one or more of magnesium hydroxide, aluminum hydroxide, and zinc borate, preferably two or more of these three compounds.

[0026] As a further technical solution, when the inorganic flame retardant includes magnesium hydroxide, the average particle size of the magnesium hydroxide is 1~10μm, preferably 3~5μm.

[0027] As a further technical solution, when the inorganic flame retardant includes aluminum hydroxide, the average particle size of the aluminum hydroxide is 1~10μm, preferably 3~5μm.

[0028] As a further technical solution, when the inorganic flame retardant includes zinc borate, the average particle size of the zinc borate is 1~10μm, preferably 3~7μm.

[0029] As a further technical solution, the inorganic flame retardant is composed of aluminum hydroxide, magnesium hydroxide, zinc borate and calcium carbonate in a mass ratio of 3~4:1~2:6:2, with a preferred mass ratio of 3:2:6:2~4:1:6:2.

[0030] As a further technical solution, the calcium carbonate is iron powder coated calcium carbonate.

[0031] In this invention, calcium carbonate is first coated with iron powder. The iron powder coating can impart more active groups to the surface of calcium carbonate. Then, it is modified by butyl acrylate-sodium styrene sulfonate-vinyltriethoxysilane copolymer, which can improve the modification effect of calcium carbonate, thereby improving the dispersibility of calcium carbonate in the system and its compatibility with the matrix, and achieving the effect of further improving the mechanical properties and flame retardant properties of ceramicized silicone rubber.

[0032] As a further technical solution, the raw materials for iron powder coating calcium carbonate include iron powder and calcium carbonate in a mass ratio of 3~7:100.

[0033] In this invention, iron powder coated calcium carbonate can be prepared by any conventional method in the art, such as high-speed mechanical stirring, impact, grinding or ball milling, preferably grinding or ball milling, more preferably ball milling, with a ball milling speed of 300~700 rpm and a ball milling time of 5~10 h.

[0034] As a further technical solution, the molecular weight of the methyl vinyl silicone rubber is 400,000~700,000 g / mol, and the vinyl molar content is 0.1%~0.8%, preferably the molecular weight of the methyl vinyl silicone rubber is 500,000~600,000 g / mol, and the vinyl molar content is 0.1%~0.2%.

[0035] As a further technical solution, the ceramic powder includes one or two of mica powder and kaolin.

[0036] As a further technical solution, when the ceramic powder includes mica powder, the average particle size of the mica powder is 10~40μm, preferably 10~20μm.

[0037] As a further technical solution, when the ceramic powder includes kaolin, the average particle size of the kaolin is 3~45μm, preferably 4~20μm.

[0038] As a further technical solution, the flux is glass powder, the average particle size of the glass powder is 5~30μm, and the softening point of the glass powder is 400~600℃.

[0039] As a further technical solution, the vulcanizing agent includes one or more of dicumyl peroxide, 2,4-dichlorobenzoyl peroxide, and 2,5-dimethyl-2,5-bis(tert-butyl peroxide), preferably 2,5-dimethyl-2,5-bis(tert-butyl peroxide).

[0040] As a further technical solution, the coupling agent includes one or more of silane coupling agents KH550, KH560, and KH570, preferably silane coupling agent KH560.

[0041] This invention also proposes a method for preparing fire-retardant and flame-retardant ceramicized silicone rubber, comprising the following steps:

[0042] A1. After kneading silicone rubber and fumed silica, add the remaining raw materials except for the vulcanizing agent and mix to obtain a mixture.

[0043] A2. After mixing the mixture with the vulcanizing agent, the mixture is kneaded and vulcanized to obtain fire-retardant ceramicized silicone rubber.

[0044] As a further technical solution, the kneading time is 20-30 minutes.

[0045] As a further technical solution, in step A1, the mixing time is 60~120min.

[0046] As a further technical solution, in step A2, the mixing time is 10~20 minutes.

[0047] As a further technical solution, the vulcanization includes a first-stage vulcanization and a second-stage vulcanization. The temperature of the first-stage vulcanization is 150~180℃, the time is 5~10min, and the pressure is 10~20MPa. The temperature of the second-stage vulcanization is 180~200℃, and the time is 100~120min.

[0048] The working principle and beneficial effects of this invention are as follows:

[0049] Traditional surface modifiers are small-molecule coupling agents such as silane coupling agents and titanate coupling agents. Due to their short molecular chain segments and few reactive functional groups, the degree of organication of the interface layer formed by modification is low, resulting in limited modification effects. This invention uses a macromolecular copolymer, butyl acrylate-sodium styrene sulfonate-vinyltriethoxysilane, as a surface modifier for inorganic flame retardants. This introduces long molecular chain segments with specific functional groups onto the surface of the inorganic flame retardant particles, making the surface of the inorganic flame retardant particles organic. This facilitates dispersion in the system, reduces the aggregation of inorganic flame retardants in the system, and improves the mechanical and flame-retardant properties of ceramicized silicone rubber. Detailed Implementation

[0050] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0051] The parameters of the raw materials in the following examples and comparative examples are as follows:

[0052] Methyl vinyl silicone rubber: molecular weight 600,000 g / mol, vinyl content 0.12%;

[0053] Fumed silica: specific surface area is 250m² 2 / g;

[0054] Ceramic powder: composed of mica powder and kaolin in a mass ratio of 3:2, wherein the average particle size (D50) of the mica powder is 15μm and the average particle size (D50) of the kaolin is 10μm;

[0055] Vulcanizing agent: 2,5-dimethyl-2,5-bis(tert-butylperoxide)hexane;

[0056] Coupling agent: silane coupling agent KH560;

[0057] Iron powder: particle size 50nm, density 7.845g / cm³ 3 Its microscopic morphology is spherical;

[0058] Calcium carbonate: particle size 1250 mesh;

[0059] Magnesium hydroxide: average particle size is 3 μm;

[0060] Aluminum hydroxide: average particle size is 3μm;

[0061] Zinc borate: average particle size is 5 μm;

[0062] Flux: Low melting point (melting point of 500℃) glass powder with an average particle size D50 of 5μm.

[0063] Example 1

[0064] A fire-retardant ceramicized silicone rubber, the raw materials of which include the following components in parts by weight: 100 parts methyl vinyl silicone rubber, 10 parts fumed silica, 55 parts modified flame retardant, 50 parts ceramic powder, 10 parts flux, 0.7 parts vulcanizing agent, and 1 part coupling agent.

[0065] The synthesis method of the macromolecular surface modifier butyl acrylate-sodium styrene sulfonate-vinyltriethoxysilane is as follows:

[0066] 5.69 g of butyl acrylate, 3.17 g of vinyltriethoxysilane, and 1.14 g of sodium styrene sulfonate were added to a three-necked flask containing 40 g of N,N-dimethylformamide as solvent. The flask was purged with nitrogen and heated to 50 °C, then stirred for 10 min. 50 g of a mixed solution (composed of azobisisobutyronitrile, dodecanethiol, and N,N-dimethylformamide in a mass ratio of 6:1:25) was added dropwise to the flask. The temperature was raised to 65 °C and the reaction was maintained for 1.5 h. After the reaction was completed, the solution was cooled to room temperature, and the solvent was removed to obtain a terpolymer of butyl acrylate-sodium styrene sulfonate-vinyltriethoxysilane.

[0067] The preparation method of the modified flame retardant is as follows:

[0068] The compound flame retardant (composed of magnesium hydroxide and aluminum hydroxide in a mass ratio of 10:15), butyl acrylate-sodium styrene sulfonate-vinyltriethoxysilane terpolymer, and water were mixed in a mass ratio of 1:0.05:2.5 and milled in a sand mill for 40 min. After the reaction was completed, the mixture was filtered, and the solid was extracted with 95% ethanol (volume fraction) as solvent at 60 °C for 12 h using a Soxhlet extractor. The solid was then dried in a forced-air drying oven until completely dry, ball-milled, and sieved to obtain a modified flame retardant with a particle size of 5 μm.

[0069] The preparation method of the above-mentioned fire-retardant ceramicized silicone rubber includes the following steps:

[0070] A1: Methyl vinyl silicone rubber and fumed silica are kneaded at room temperature for 30 minutes to obtain a compound;

[0071] A2: Add coupling agent, modified flame retardant, ceramic powder and flux to the mixed adhesive, and mix for 60 minutes to obtain the mixture;

[0072] A3: After the mixture has cooled to room temperature, add the vulcanizing agent and mix for 10 minutes;

[0073] A4: The material obtained from A3 is subjected to a first-stage vulcanization and a second-stage vulcanization to obtain fire-retardant ceramicized silicone rubber. The first vulcanization temperature is 170℃, the time is 5min, and the pressure is 15MPa. The second vulcanization temperature is 200℃ and the time is 120min.

[0074] Example 2

[0075] A fire-retardant ceramicized silicone rubber, the raw materials of which include the following components in parts by weight: 100 parts methyl vinyl silicone rubber, 20 parts fumed silica, 35 parts modified flame retardant, 20 parts ceramic powder, 15 parts flux, 2 parts vulcanizing agent, and 5 parts coupling agent.

[0076] The synthesis method of the macromolecular surface modifier butyl acrylate-sodium styrene sulfonate-vinyltriethoxysilane is as follows:

[0077] 3.99 g of butyl acrylate, 4.94 g of vinyltriethoxysilane, and 1.07 g of sodium styrene sulfonate were added to a three-necked flask containing 40 g of N,N-dimethylformamide as solvent. The flask was purged with nitrogen and heated to 60 °C, and stirred for 5 min. 50 g of a mixed solution (composed of azobisisobutyronitrile, dodecanethiol, and N,N-dimethylformamide in a mass ratio of 6:1:25) was added dropwise to the three-necked flask. The flask was heated to 75 °C and the reaction was maintained at this temperature for 1 h. After the reaction was completed, the solution was cooled to room temperature and the solvent was removed to obtain a terpolymer of butyl acrylate-sodium styrene sulfonate-vinyltriethoxysilane.

[0078] The preparation method of the modified flame retardant is as follows:

[0079] The compound flame retardant (composed of magnesium hydroxide and aluminum hydroxide in a mass ratio of 10:15), butyl acrylate-sodium styrene sulfonate-vinyltriethoxysilane terpolymer, and water were mixed in a mass ratio of 1:0.1:5 and milled in a sand mill for 20 min. After the reaction was completed, the mixture was filtered, and the solid was extracted with 95% ethanol (volume fraction) as solvent at 50 °C for 15 h using a Soxhlet extractor. The solid was then dried in a forced-air drying oven until completely dry, and then ball-milled and sieved to obtain a modified flame retardant with a particle size of 10 μm.

[0080] The preparation method of the above-mentioned fire-retardant ceramicized silicone rubber includes the following steps:

[0081] A1: Methyl vinyl silicone rubber and fumed silica are kneaded at room temperature for 20 minutes to obtain a compound;

[0082] A2: Add coupling agent, modified flame retardant, ceramic powder and flux to the mixed adhesive, and mix for 120 minutes to obtain the mixture;

[0083] A3: After the mixture has cooled to room temperature, add the vulcanizing agent and mix for 20 minutes;

[0084] A4: The material obtained in A3 is subjected to a first-stage vulcanization and a second-stage vulcanization to obtain fire-retardant ceramicized silicone rubber. The first vulcanization temperature is 160℃, the time is 10min, and the pressure is 20MPa. The second vulcanization temperature is 190℃ and the time is 100min.

[0085] Example 3

[0086] The only difference from Example 1 is that the compound flame retardant is composed of aluminum hydroxide and zinc borate in a mass ratio of 10:15.

[0087] Example 4

[0088] The only difference from Example 1 is that the compound flame retardant is composed of magnesium hydroxide and zinc borate in a mass ratio of 10:15.

[0089] Example 5

[0090] The only difference from Example 1 is that the compound flame retardant is composed of aluminum hydroxide, magnesium hydroxide and zinc borate in a mass ratio of 20:5:30.

[0091] Example 6

[0092] The only difference from Example 1 is that the compound flame retardant is composed of aluminum hydroxide, magnesium hydroxide and zinc borate in a mass ratio of 15:10:30.

[0093] Example 7

[0094] The only difference from Example 5 is that:

[0095] A fire-retardant ceramicized silicone rubber, the raw materials of which include the following components in parts by weight: 100 parts methyl vinyl silicone rubber, 10 parts fumed silica, 65 parts modified flame retardant, 50 parts ceramic powder, 10 parts flux, 0.7 parts vulcanizing agent, and 1 part coupling agent.

[0096] The compound flame retardant is composed of aluminum hydroxide, magnesium hydroxide, zinc borate and calcium carbonate in a mass ratio of 20:5:30:10.

[0097] Example 8

[0098] The only difference from Example 7 is that the calcium carbonate is iron powder coated calcium carbonate, which is prepared by the following method: iron powder and calcium carbonate are mixed at a mass ratio of 3:100 and then ball-milled at 300 rpm for 10 hours to obtain iron powder coated calcium carbonate.

[0099] Example 9

[0100] The only difference from Example 6 is that:

[0101] A fire-retardant ceramicized silicone rubber, the raw materials of which include the following components in parts by weight: 100 parts methyl vinyl silicone rubber, 10 parts fumed silica, 65 parts modified flame retardant, 50 parts ceramic powder, 10 parts flux, 0.7 parts vulcanizing agent, and 1 part coupling agent.

[0102] The compound flame retardant is composed of aluminum hydroxide, magnesium hydroxide, zinc borate, and iron powder coated calcium carbonate in a mass ratio of 15:10:30:10. The iron powder coated calcium carbonate is prepared by the following method: iron powder and calcium carbonate are mixed in a mass ratio of 7:100 and then ball-milled at 700 rpm for 5 hours to obtain iron powder coated calcium carbonate.

[0103] Comparative Example 1

[0104] The only difference from Example 1 is that the compound flame retardant is composed of aluminum hydroxide and zinc borate in a mass ratio of 10:15, and no macromolecular surface modifier is used for surface modification.

[0105] Comparative Example 2

[0106] The only difference from Example 1 is that the compound flame retardant is composed of aluminum hydroxide, magnesium hydroxide and zinc borate in a mass ratio of 20:5:30, and no macromolecular surface modifier is used for surface modification.

[0107] Comparative Example 3

[0108] The only difference from Example 1 is that the compound flame retardant is composed of aluminum hydroxide, magnesium hydroxide and zinc borate in a mass ratio of 15:10:30, and no macromolecular surface modifier is used for surface modification.

[0109] Comparative Example 4

[0110] The only difference from Example 1 is that the compound flame retardant is composed of aluminum hydroxide, magnesium hydroxide, and zinc borate in a mass ratio of 20:5:30, and is surface modified using vinyltriethoxysilane. The modification method is as follows:

[0111] Measure 70 mL of anhydrous ethanol, 20 mL of vinyltriethoxysilane, and 10 mL of deionized water, mix and stir at room temperature for 30 min to obtain a mixed solution. Add 20 g of the compounded flame retardant to the mixed solution and stir at 80 °C for 3 h. After modification, wash with deionized water and dry in a forced-air oven at 70 °C for 24 h. Use a ball mill to ball mill the dried modified compounded flame retardant and sieve it to obtain a modified flame retardant with a particle size of 5 μm.

[0112] The fire-retardant and flame-retardant ceramicized silicone rubbers obtained in the above embodiments and comparative examples were subjected to performance tests according to the following methods:

[0113] (1) Hardness: The hardness (Shore A) of the sample was tested according to the test method specified in GB / T 531.1-2008 "Test method for indentation hardness of vulcanized rubber or thermoplastic rubber - Part 1: Shore hardness tester method (Shore hardness)".

[0114] (2) Tensile strength and elongation at break: The tensile strength and elongation at break of the sample shall be tested in accordance with the test method specified in GB / T 528-2009 "Determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber". The sample type is a type 1 dumbbell-shaped sample with a thickness of 2 mm.

[0115] (3) Vertical flammability rating: The vertical flammability rating of the sample shall be tested in accordance with the test method specified in GB / T 10707-2008 "Determination of the flammability of rubber";

[0116] (4) Oxygen index: The oxygen index of the sample shall be tested in accordance with the test method specified in GB / T 10707-2008 "Determination of the flammability of rubber";

[0117] (5) Fireproof and heat insulation performance:

[0118] Test conditions:

[0119] a) Flame temperature is 1100℃, heat flux density is ≥9.3 Btu.s / ft 2 (10.6W / cm) 2 );

[0120] b) Fire test duration: 15 minutes;

[0121] c) Burners, heat flow meters, thermocouples, and testing instruments / meters shall be within their validity period and be calibrated to be qualified and accurate;

[0122] d) Record the experiment in the form of videos and photos;

[0123] Test dimensions:

[0124] The sample is a circular rubber sheet with an outer diameter of 120 mm and a thickness of 6 mm;

[0125] Experimental steps:

[0126] a) Positioning adjustment: Place the burner in the test position on the test bench. The thermocouple should be located above the center line of the burner, 102 mm away from the sample, and the heat flow meter should be located at the end of the thermocouple.

[0127] b) Flame parameter adjustment: Place the burner in the preheating position, ignite the burner, and preheat for 5 minutes. After preheating, move the thermocouple to the preheating position. Once the temperature reaches 1100℃, move the thermocouple to the testing position, and then move the heat flux meter to the testing position. Confirm that the heat flux density is ≥9.3 Btu.s / ft. 2 (10.6W / cm) 2 If the heat flux density or temperature data is not within the required range, the burner should be adjusted until the flame temperature and heat flux density meet the requirements.

[0128] c) Install the sample fixture horizontally on the sample holder, and attach a thermocouple tightly to the center point of the back of the sample to record the temperature of the back of the sample.

[0129] d) Turn on the burner, preheat for 5 minutes, then position the burner in the test position and start timing. The test time is 15 minutes. Observe the test phenomena during the test and record the temperature change curve of the center of the back of the sample over time.

[0130] e) After the test time is up, turn off the burner and record the test results.

[0131] The performance test results are recorded in Table 1. " / " indicates that the performance test was not performed.

[0132] Table 1 Performance test results of fire-retardant ceramicized silicone rubber

[0133]

[0134] As shown in Table 1, the tensile strength and elongation at break of the fire-retardant ceramicized silicone rubbers obtained in Examples 3 and 5-6 are higher than those in Comparative Examples 1-4, indicating that the surface modification of the ceramicized silicone rubber with the inorganic flame retardant via the macromolecular copolymer butyl acrylate-sodium styrene sulfonate-vinyltriethoxysilane can improve the mechanical properties of the ceramicized silicone rubber. Furthermore, the vertical flammability rating, fire resistance, and thermal insulation properties of the fire-retardant ceramicized silicone rubbers obtained in Examples 3 and 5-6 are higher than those in Comparative Examples 1-3. Simultaneously, the oxygen index of the fire-retardant ceramicized silicone rubber obtained in Example 3 is higher than that of Comparative Example 1, the oxygen index of the fire-retardant ceramicized silicone rubber obtained in Example 5 is higher than that of Comparative Examples 2 and 4, and the oxygen index of the fire-retardant ceramicized silicone rubber obtained in Example 6 is higher than that of Comparative Example 3. This indicates that the surface modification of the ceramicized silicone rubber with the inorganic flame retardant via the macromolecular copolymer butyl acrylate-sodium styrene sulfonate-vinyltriethoxysilane can also improve the flame retardant, fire resistance, and thermal insulation properties of the ceramicized silicone rubber.

[0135] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A fire-retardant and flame-retardant ceramicized silicone rubber, characterized in that, The raw materials include the following components in parts by weight: 100 parts silicone rubber, 5-20 parts fumed silica, 10-65 parts modified flame retardant, 20-50 parts ceramic powder, 5-20 parts flux, 0.5-2 parts vulcanizing agent, and 1-7 parts coupling agent. The modified flame retardant is composed of butyl acrylate-sodium styrene sulfonate-vinyltriethoxysilane copolymer and inorganic flame retardant. The inorganic flame retardant is composed of aluminum hydroxide, magnesium hydroxide, zinc borate, and calcium carbonate in a mass ratio of 3-4:1-2:6:

2. The calcium carbonate is iron powder coated calcium carbonate, and the raw materials for iron powder coated calcium carbonate include iron powder and calcium carbonate in a mass ratio of 3-7:

100.

2. The fire-retardant and flame-retardant ceramicized silicone rubber according to claim 1, characterized in that, The mass ratio of the butyl acrylate-sodium styrene sulfonate-vinyltriethoxysilane copolymer to the inorganic flame retardant is 0.01~0.1:

1.

3. The fire-retardant and flame-retardant ceramicized silicone rubber according to claim 1, characterized in that, The preparation method of the butyl acrylate-sodium styrene sulfonate-vinyltriethoxysilane copolymer includes the following steps: After mixing butyl acrylate, vinyltriethoxysilane, and sodium styrene sulfonate with a solvent, the mixture is heated to 50-60°C and stirred for 5-10 minutes. A mixed solution of initiator and chain transfer agent is then added and reacted at 65-75°C for 1-1.5 hours. After the reaction is completed, the mixture is cooled and the solvent is removed to obtain a butyl acrylate-sodium styrene sulfonate-vinyltriethoxysilane copolymer.

4. The fire-retardant and flame-retardant ceramicized silicone rubber according to claim 3, characterized in that, The mass ratio of butyl acrylate, vinyltriethoxysilane, and sodium styrene sulfonate is 3.99~5.69:3.17~4.94:1.07~1.

14.

5. The fire-retardant and flame-retardant ceramicized silicone rubber according to claim 1, characterized in that, The preparation method of the modified flame retardant includes the following steps: S1. After mixing the inorganic flame retardant, butyl acrylate-sodium styrene sulfonate-vinyltriethoxysilane copolymer and water, the mixture is milled and filtered to obtain the pretreated flame retardant. S2. Extract the pretreated flame retardant and dry it to obtain a modified flame retardant.

6. The fire-retardant and flame-retardant ceramicized silicone rubber according to claim 5, characterized in that, In step S2, the dried material is ball-milled to a particle size of 5~10μm.

7. A method for preparing fire-retardant and flame-retardant ceramicized silicone rubber, used to prepare the fire-retardant and flame-retardant ceramicized silicone rubber according to any one of claims 1 to 6, characterized in that, Includes the following steps: A1. After kneading silicone rubber and fumed silica, add the remaining raw materials except for the vulcanizing agent and mix to obtain a mixture. A2. After mixing the mixture with the vulcanizing agent, the mixture is kneaded and vulcanized to obtain fire-retardant ceramicized silicone rubber.

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