Flame Retardant and Heat Insulating Silicone Rubber Composition, Flame Retardant and Heat Insulating Material, Preparation Method Thereof and Application

Abstract

The present invention discloses a flame-retardant and heat-insulating silicone rubber composition, a flame-retardant and heat-insulating material, and a preparation method and application thereof, belonging to the technical field of polymer materials, and comprising the following components in parts by weight: 100 parts of vinyl silicone rubber, 1 to 5 parts of hydrogen-containing silicone oil, 5 to 30 parts of vinyl-modified potassium hexatitanate whiskers, 10 to 40 parts of hollow microspheres, 0.7 to 32 parts of flame retardant, and 0.6 to 9 parts of additives; the aspect ratio of the vinyl-modified potassium hexatitanate whiskers is 10 to 100. The present invention uses vinyl silicone rubber as the matrix, and under the combined action of hydrogen-containing silicone oil, vinyl-modified potassium hexatitanate whiskers, hollow microspheres, and flame retardant, effectively improves the flame-retardant and heat-insulating effect of the composition. The composition is very suitable for preparing secondary batteries, especially for preparing the flame-retardant and heat-insulating pads of secondary batteries, effectively blocking the heat radiation generated by the thermal runaway high temperature of the secondary battery and reducing the risk of thermal runaway.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, and particularly relates to a flame-retardant and heat-insulating silicone rubber composition, a flame-retardant and heat-insulating material, a preparation method thereof and an application thereof. Background Art

[0002] At present, new energy electric vehicles mainly use lithium-ion batteries as power batteries. Under harsh conditions, thermal runaway of the battery is the primary safety issue for electric vehicles. The power battery consists of multiple battery cells. When the battery cells are squeezed, deformed, punctured, overcharged, etc., the temperature becomes too high, resulting in thermal runaway of the battery, and ultimately leading to the fire and explosion of the electric vehicle. Thermal runaway of the battery is an important problem in the electric vehicle industry. The new national standard requires that after the thermal runaway of a single battery cell, the battery system does not extinguish or explode within five minutes to reserve a safe escape time for the occupants. In order to ensure that the power battery does not undergo thermal runaway, it is often necessary to use heat-insulating materials to prevent the heat from the thermally runaway battery cell from being transferred to the surrounding battery cells.

[0003] Commonly used heat-insulating materials for power batteries include foam, plastic foam, ultra-fine glass wool, high-silica oxygen cotton, vacuum insulation panel, silica aerogel, etc. Currently, aerogel heat-insulating materials are mainly used, but aerogels have disadvantages such as easy powdering, slagging, low compressive strength, poor conformability, and high price.

[0004] Potassium hexatitanate whiskers were initially developed by DuPont for use as high-temperature heat-insulating materials in aviation. It has a negative temperature coefficient. The thermal conductivity at room temperature is 0.089 W / (mK), the thermal conductivity at 530 °C is 0.038 W / (mK), and the thermal conductivity at 800 °C is only 0.017 W / (mK). At the same time, it has excellent infrared ray reflection performance; in addition, potassium hexatitanate whiskers also have excellent electrical insulation, high-temperature resistance, acid and alkali resistance, abrasion resistance, low hardness and other characteristics, and the price is moderate, making it an ideal heat-insulating material. However, potassium hexatitanate whiskers have disadvantages such as poor water resistance and easy oxidation at high temperatures. When potassium hexatitanate whiskers are filled in solid silicone rubber, the thermal conductivity at room temperature is often greater than 0.15 W / (mK), making it difficult to meet the lightweight and heat-insulating requirements of current new energy vehicle batteries.

[0005] In view of this, the present application is proposed. Summary of the Invention

[0006] The object of the present invention is to overcome the deficiencies of the prior art and provide a flame-retardant and heat-insulating silicone rubber composition, a flame-retardant and heat-insulating material, a preparation method thereof and an application thereof. The composition has excellent flame-retardant and heat-insulating effects. The composition is very suitable for preparing secondary batteries, especially suitable for preparing flame-retardant and heat-insulating pads for secondary batteries, effectively blocking the heat radiation generated by the high temperature of the thermal runaway of the secondary battery and reducing the risk of thermal runaway.

[0007] To achieve the above object, the first aspect of the present application provides a flame-retardant and heat-insulating silicone rubber composition, comprising the following components in parts by weight: 100 parts of vinyl silicone rubber, 1 to 5 parts of hydrogen-containing silicone oil, 5 to 30 parts of vinyl-modified potassium hexatitanate whiskers, 10 to 40 parts of hollow microspheres, 0.7 to 32 parts of flame retardant, and 0.6 to 9 parts of additives;

[0008] The mass percentage content of vinyl in the vinyl-modified potassium hexatitanate whiskers is 0.01 to 0.2 wt%.

[0009] The present invention creatively combines the above-mentioned raw materials. With vinyl silicone rubber as the matrix, under the combined action of hydrogen-containing silicone oil, vinyl-modified potassium hexatitanate whiskers, hollow microspheres, and flame retardant, the flame-retardant and heat-insulating effect of the composition is effectively improved. The composition is very suitable for preparing secondary batteries, especially for preparing flame-retardant and heat-insulating pads for secondary batteries, effectively blocking the heat radiation generated by the thermal runaway of the secondary battery at high temperature and reducing the risk of thermal runaway.

[0010] The present invention combines vinyl-modified potassium hexatitanate whiskers and hollow microspheres. The potassium hexatitanate whiskers have excellent infrared ray reflection performance, high temperature resistance, acid and alkali resistance, and abrasion resistance. After vinyl modification, the disadvantages of potassium hexatitanate whiskers such as hydrolysis resistance and easy oxidation at high temperature are effectively improved, ensuring the stability of potassium hexatitanate whiskers. After vinyl modification, the compatibility and dispersibility of potassium hexatitanate whiskers in the system are effectively improved, enabling them to be grafted onto silicone rubber in a specific form, effectively increasing the crosslinking density, improving the processing performance, and enhancing the fluidity of the rubber compound. The hollow microspheres can effectively reduce the material density and thermal conductivity, ensuring the heat insulation performance and lightweight of the product. Based on the excellent compressive strength of the hollow microspheres, the compressive strength of the material can be effectively increased, and the heat generated instantaneously by the secondary battery can be blocked to avoid thermal runaway. Among them, the hollow microspheres can further reduce the overall thermal conductivity of potassium hexatitanate whiskers in the composition and further improve the disadvantages of poor water resistance and easy oxidation at high temperature of potassium hexatitanate whiskers, while retaining the application characteristics of the negative temperature thermal conductivity of potassium hexatitanate whiskers. Under the synergistic effect of the two, the flame retardancy and heat insulation of the composition are effectively improved, and the thermal conductivity of the composition shows a negative growth as the temperature increases.

[0011] By controlling the vinyl content of the vinyl-modified potassium hexatitanate whiskers to be 0.01 to 0.2 wt%, the present invention enables part of the vinyl-modified potassium hexatitanate whiskers to participate in the crosslinking of silicone rubber to form a crosslinking network, and part to form a filling network with hollow microspheres, improving the compatibility and dispersibility in the system, avoiding agglomeration, and effectively improving the flame-retardant and heat-insulating effect of the composition.

[0012] As an embodiment of the present application, the mass percentage content of vinyl in the vinyl-modified potassium hexatitanate whiskers is 0.05 to 0.1 wt%, and especially when controlled within this range, a better cross-linked filling network can be formed to avoid too high cross-linking density.

[0013] Among them, in the flame-retardant and heat-insulating silicone rubber composition of the present invention, the mass percentage content of the vinyl silicone rubber is not less than 50%.

[0014] As an embodiment of the present application, in the flame-retardant and heat-insulating silicone rubber composition of the present invention, the mass percentage content of the vinyl silicone rubber is 50 to 75%.

[0015] As an embodiment of the present application, in the flame-retardant and heat-insulating silicone rubber composition of the present invention, the mass percentage content of the vinyl silicone rubber is 52 to 73%.

[0016] As an embodiment of the present application, the aspect ratio of the vinyl-modified potassium hexatitanate whiskers is 10 to 100; by controlling the aspect ratio of the vinyl-modified potassium hexatitanate whiskers to be 10 to 100 in the present invention, the dispersibility and compatibility of the vinyl-modified potassium hexatitanate whiskers in the system can be improved, the cross-linking density can be more effectively increased, a stronger and denser cross-linked network structure can be formed, the thermal conductivity coefficient of the composition can be effectively reduced, the mechanical properties can be improved, and at the same time, a dense filling network can be formed with the hollow microspheres, further improving the flame-retardant and heat-insulating effects of the composition.

[0017] As an embodiment of the present application, the aspect ratio of the vinyl-modified potassium hexatitanate whiskers is 26 to 50.

[0018] As an embodiment of the present application, the diameter of the vinyl-modified potassium hexatitanate whiskers is 0.1 to 5 μm, and the length is 0.2 to 100 μm.

[0019] As an embodiment of the present application, the preparation method of the vinyl-modified potassium hexatitanate whiskers includes the following steps:

[0020] Mix potassium carbonate, metatitanic acid and water evenly, filter press, dry, crush, sinter at 1000 to 1200 °C for 1 to 3 h first, and then sinter at 650 to 750 °C for 1 to 2 h to obtain a precursor;

[0021] Add the precursor and vinyl coupling agent to a solvent, mix evenly, and ball mill to obtain vinyl-modified potassium hexatitanate whiskers.

[0022] The vinyl-modified potassium hexatitanate whiskers prepared by the preparation method of the present invention can effectively improve the disadvantages of poor water resistance and easy oxidation at high temperature of potassium hexatitanate whiskers, make them uniformly dispersed in the composition, and form a dense cross-linked filling network, thereby effectively improving the flame-retardant and heat-insulating effects of the composition.

[0023] As an embodiment of the present application, the molar ratio of potassium carbonate to metatitanic acid is 1:(4-8).

[0024] Among them, by controlling the ball milling parameters and sintering parameters, the diameter and length of the whiskers can be adjusted, and thus the aspect ratio can be controlled.

[0025] Among them, the solvent includes at least one of ethanol, water, acetone, ethanol, methanol, N,N-dimethylformamide, acetonitrile, dimethyl sulfoxide, sulfolane, tetrahydrofuran, 2-methyltetrahydrofuran, ethylene nitrate, ethylene carbonate, 1,4-butyrolactone, and dimethylacetamide.

[0026] Among them, the ball milling speed is 10-100 rpm, and the ball milling time is 60-120 min.

[0027] As an embodiment of the present application, the vinyl coupling agent is 0.1-2% of the mass of the precursor. By controlling the mass ratio of the vinyl coupling agent to the precursor, the content of vinyl can be controlled.

[0028] It should be noted that in the present invention, the length and diameter of the vinyl-modified potassium hexatitanate whiskers are measured by a microscope method: 100 samples of vinyl-modified potassium hexatitanate whiskers are placed under a microscope for observation, the length and diameter of all vinyl-modified potassium hexatitanate whiskers in the samples are calculated, and the average value is calculated to obtain the length and diameter of the vinyl-modified potassium hexatitanate whiskers, and then the aspect ratio is calculated.

[0029] Among them, the mass percentage content of vinyl in the vinyl-modified potassium hexatitanate whiskers is measured by near-infrared method.

[0030] As an embodiment of the present application, the vinyl coupling agent includes at least one of vinyltris(2-methoxyethoxy)silane, vinyltrimethoxysilane, and vinyltriethoxysilane.

[0031] As an embodiment of the present application, the vinyl silicone rubber includes the following components in parts by weight: 75-85 parts of methyl vinyl silicone oil, 25-35 parts of vinyl silicone resin, 45-55 parts of fumed silica, and 2-4 parts of structure control agent;

[0032] The structure control agent includes at least one of hexamethyldisilazane, dimethyldichlorosilane, hydroxy silicone oil, trimethylethoxysilane, vinyltriethoxysilane, hexamethyldisiloxane, and n-heptanol.

[0033] The vinyl silicone rubber described in the present invention has excellent stability. In the system of the present invention, the vinyl silicone rubber has excellent compatibility with other raw materials, can improve the processing performance of the composition, improve the formability, has moderate fluidity, promotes the uniform dispersion of other components in the system, can form a dense cross-linked network structure, and at the same time promotes the formation of a filled network structure, improves the intermolecular force, avoids too dense cross-linking points, avoids stress concentration, and effectively improves the flame retardancy and heat insulation effect of the composition.

[0034] Among them, the present invention places no limit on the preparation method of the vinyl silicone rubber. Those skilled in the art can prepare the vinyl silicone rubber from methyl vinyl silicone oil, vinyl silicone resin, fumed silica, and structure control agent according to the formula disclosed in the present invention by conventional technical means in the art.

[0035] Exemplarily, the preparation method of the vinyl silicone rubber is: kneading and molding methyl vinyl silicone oil, vinyl silicone resin, fumed silica, and structure control agent in a kneader to obtain the vinyl silicone rubber.

[0036] More specifically, the preparation method of the vinyl silicone rubber is: adding methyl vinyl silicone oil, vinyl silicone resin, fumed silica, and structure control agent to a kneader, at 25-45°C, controlling the kneading frequency at 35-50 Hz, turning on the cold cycle, and maintaining the vacuum degree ≤ -0.098 MPa until the rubber material is kneaded and molded; after the rubber material is molded, turn on the hot cycle, control the temperature at 150-160°C, maintain the vacuum degree ≤ -0.098 MPa, and hot knead for 2-4 hours, then cool down to room temperature and discharge to obtain the vinyl silicone rubber.

[0037] As an embodiment of the present application, the viscosity of the methyl vinyl silicone oil at 25°C is 800-1200 mPa·s.

[0038] As an embodiment of the present application, the viscosity of the vinyl silicone resin at 25°C is 800-1000 mPa·s.

[0039] As an embodiment of the present application, the hollow microspheres include at least one of hollow glass microspheres, aluminosilicate hollow microspheres, alumina hollow microspheres, carbon hollow microspheres, and zirconia hollow microspheres.

[0040] As an embodiment of the present application, the density of the hollow microspheres is 0.125-0.38 g / cm 3 , and the average particle size of the hollow microspheres is 35-65 μm.

[0041] As an embodiment of the present application, the weight ratio of the vinyl-modified potassium hexatitanate whiskers to the hollow microspheres is 1:(1 - 3). By controlling the mass ratio within this range, the disadvantages of poor water resistance and easy oxidation at high temperatures of the potassium hexatitanate whiskers can be effectively improved. At the same time, the vinyl-modified potassium hexatitanate whiskers and the hollow microspheres can be better filled in the system, effectively improving the flame retardant and heat insulation performance.

[0042] As an embodiment of the present application, the weight ratio of the sum of the vinyl-modified potassium hexatitanate whiskers and the hollow microspheres to the vinyl silicone rubber is (0.4 - 0.5):1. By controlling the vinyl-modified potassium hexatitanate whiskers and the hollow microspheres within this range, the compatibility of the system is effectively improved, and the dispersibility and compatibility of the vinyl-modified potassium hexatitanate whiskers and the hollow microspheres in the system are improved. At the same time, it promotes the formation of a dense cross-linked network structure and a filling network structure, thereby more effectively improving the flame retardant and heat insulation performance.

[0043] As an embodiment of the present application, the flame retardant includes at least one of a silica gel flame retardant, a silicate aluminate flame retardant, and a nitrogen-containing flame retardant; the nitrogen-containing flame retardant includes at least one of benzotriazole, 1-hydroxybenzotriazole, and 1-(trimethylsilyl)benzotriazole.

[0044] As an embodiment of the present application, the flame retardant includes a silica gel flame retardant, a silicate aluminate flame retardant, and a nitrogen-containing flame retardant, and the mass ratio of the silica gel flame retardant, the silicate aluminate flame retardant, and the nitrogen-containing flame retardant is (0.1 - 2):(0.3 - 28):(0.3 - 2). By controlling the mass of the three within this range, in the specific system of the present invention, the silica gel flame retardant has a good flame retardant effect, the silicate flame retardant has a good coordination effect with the silica gel system, and can effectively bond the amorphous silica generated by the thermal decomposition of silicone rubber at high temperatures to form a protective outer layer. The nitrogen-containing flame retardant forms a shielding layer at high temperatures under the action of a catalyst, achieving a flame retardant effect.

[0045] As an embodiment of the present application, the auxiliary agent includes at least one of a heat-resistant agent, a catalyst, and an inhibitor.

[0046] As an embodiment of the present application, the heat-resistant agent includes one or more of silver nanopowder, copper nanopowder, nanoferric oxide, cupric oxide nanoparticles, cerium oxide nanoparticles, and polyphenylene sulfide.

[0047] As an embodiment of the present application, the catalyst includes at least one of chloroplatinic acid, chloroplatinic acid-divinyltetramethylsiloxane complex, chloroplatinic acid-tetrahydrofuran complex, chloroplatinic acid-isopropanol complex, chloroplatinic acid-diethyl phthalate complex, and chloroplatinic acid-dibutyl maleate complex;

[0048] As an embodiment of the present application, the inhibitor includes at least one of 3-methyl-1-butyn-3-ol, 3-methyl-1-pentyn-3-ol, 3,5-dimethyl-1-hexyn-3-ol, and 1-ethynyl-1-cyclohexanol.

[0049] Preferably, the flame-retardant and heat-insulating silicone rubber composition of the present invention may further include at least one of an antioxidant, a mineral powder, a lubricant, a colorant, a weathering agent, an antistatic agent, and an ultraviolet light absorber.

[0050] The flame-retardant and heat-insulating silicone rubber composition of the present invention may include an antioxidant. Suitable antioxidants include but are not limited to at least one of thioester antioxidants, hindered phenol antioxidants, hydroxylamine antioxidants, phosphite antioxidants, and phosphate antioxidants.

[0051] The flame-retardant and heat-insulating silicone rubber composition of the present invention may include a mineral powder. Suitable mineral powders include but are not limited to calcium carbonate, kaolin, magnesium hydroxide, boehmite, and combinations thereof.

[0052] The flame-retardant and heat-insulating silicone rubber composition of the present invention may include a colorant. Suitable colorants include but are not limited to carbon black, titanium dioxide, zinc sulfide, iron oxide red, titanium yellow, and combinations thereof.

[0053] The flame-retardant and heat-insulating silicone rubber composition of the present invention may include a lubricant. Suitable lubricants include but are not limited to polyethylene wax, fatty acid esters, hyperbranched amides, and combinations thereof.

[0054] The flame-retardant and heat-insulating silicone rubber composition of the present invention may include a weathering agent. Suitable weathering agents include but are not limited to hindered amine light stabilizers and combinations thereof.

[0055] The flame-retardant and heat-insulating silicone rubber composition of the present invention may include an antistatic agent. Suitable antistatic agents include but are not limited to zinc oxide, manganese dioxide, chromium trioxide, and combinations thereof.

[0056] The flame-retardant and heat-insulating silicone rubber composition of the present invention may include an ultraviolet light absorber. Suitable ultraviolet light absorbers include but are not limited to hydroxybenzophenones, benzotriazoles, hydroxybenzotriazines, cyanoacrylates, nano-scale inorganic materials (such as titanium oxide, cerium oxide, and zinc oxide), and combinations thereof.

[0057] The second aspect of the present application provides a method for preparing a flame-retardant and heat-insulating silicone rubber composition, including the following steps:

[0058] Mix vinyl silicone rubber, vinyl-modified potassium hexatitanate whiskers, hollow microspheres, and a flame retardant evenly, then add hydrogen-containing silicone oil and stir evenly. Finally, add an auxiliary agent, stir evenly, and vulcanize and mold to obtain the flame-retardant and heat-insulating silicone rubber composition.

[0059] The third aspect of the present application provides an application of the described flame-retardant and heat-insulating silicone rubber composition in the preparation of flame-retardant and heat-insulating materials.

[0060] The fourth aspect of the present application provides a flame-retardant and heat-insulating material, comprising a flame-retardant and heat-insulating layer, and a fiber cloth and a release film sequentially arranged on at least one surface of the flame-retardant and heat-insulating layer; the flame-retardant and heat-insulating layer comprises the above-described flame-retardant and heat-insulating silicone rubber composition.

[0061] As an embodiment of the present application, at least one of the following (a) to (d) is satisfied:

[0062] (a) The fiber cloth comprises at least one of a glass fiber cloth, a basalt fiber cloth, and an alumina fiber cloth;

[0063] (b) The thickness of the flame-retardant and heat-insulating layer is 1 to 10 mm;

[0064] (c) The thickness of the fiber cloth is 0.02 to 0.1 mm;

[0065] (d) The thickness of the release film is 50 to 100 μm.

[0066] The fifth aspect of the present application provides an application of the flame-retardant and heat-insulating material in secondary batteries.

[0067] The beneficial effects of the present invention are as follows: The present invention uses vinyl silicone rubber as the matrix, and under the combined action of hydrogen-containing silicone oil, vinyl-modified potassium hexatitanate whiskers, hollow microspheres, and a flame retardant, the flame-retardant and heat-insulating effect of the composition is effectively improved. The described composition is very suitable for the preparation of secondary batteries, especially suitable for the preparation of flame-retardant and heat-insulating pads for secondary batteries, effectively blocking the heat radiation generated by the thermal runaway of the secondary battery at high temperature and reducing the risk of thermal runaway. Detailed Embodiments

[0068] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of the present application.

[0069] In the present application, for the technical features described in an open-ended manner, it includes a closed technical solution composed of the listed features, and also includes an open technical solution containing the listed features.

[0070] In this application, when it comes to numerical ranges, unless otherwise specified, the above numerical ranges are considered continuous and include the minimum and maximum values of the range, as well as each value between such minimum and maximum values. Further, when the range refers to integers, it includes each integer between the minimum and maximum values of the range. In addition, when multiple ranges are provided to describe features or characteristics, the ranges can be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all sub-ranges subsumed therein.

[0071] The raw materials used in the examples and comparative examples are described as follows:

[0072] Vinyl silicone rubber - 1, the preparation method is as follows: By weight, 80 parts of methyl vinyl silicone oil, 30 parts of vinyl silicone resin, 50 parts of fumed silica and 3 parts of hydroxyl silicone oil are added to a kneading machine. At 40 °C, the kneading frequency is controlled at 40 Hz, the cold cycle is started, and the vacuum degree is maintained ≤ -0.098 MPa until the rubber compound is kneaded and formed; after the rubber compound is formed, the hot cycle is started, the temperature is controlled at 155 °C, the vacuum degree is maintained ≤ -0.098 MPa, and hot kneading is carried out for 3 hours, then it is cooled to room temperature and discharged to obtain vinyl silicone rubber - 1.

[0073] Vinyl silicone rubber - 2, the preparation method is as follows: By weight, 60 parts of methyl vinyl silicone oil, 50 parts of vinyl silicone resin, 40 parts of fumed silica and 6 parts of hydroxyl silicone oil are added to a kneading machine. At 40 °C, the kneading frequency is controlled at 40 Hz, the cold cycle is started, and the vacuum degree is maintained ≤ -0.098 MPa until the rubber compound is kneaded and formed; after the rubber compound is formed, the hot cycle is started, the temperature is controlled at 155 °C, the vacuum degree is maintained ≤ -0.098 MPa, and hot kneading is carried out for 3 hours, then it is cooled to room temperature and discharged to obtain vinyl silicone rubber - 2.

[0074] Vinyl silicone rubber - 3, the preparation method is as follows: By weight, 100 parts of methyl vinyl silicone oil, 20 parts of vinyl silicone resin, 60 parts of fumed silica and 1 part of hydroxyl silicone oil are added to a kneading machine. At 40 °C, the kneading frequency is controlled at 40 Hz, the cold cycle is started, and the vacuum degree is maintained ≤ -0.098 MPa until the rubber compound is kneaded and formed; after the rubber compound is formed, the hot cycle is started, the temperature is controlled at 155 °C, the vacuum degree is maintained ≤ -0.098 MPa, and hot kneading is carried out for 3 hours, then it is cooled to room temperature and discharged to obtain vinyl silicone rubber - 3.

[0075] Methyl vinyl silicone oil: The viscosity at 25 °C is 1000 mPa·s, Ningbo Runhe New Materials Technology Co., Ltd., product number RH-Vi305.

[0076] Vinyl silicone resin: Viscosity at 25°C is 850 mPa·s, Guangdong Chenxi New Material Technology Co., Ltd., grade CX-355-2.

[0077] Hydroxy silicone oil: Dow Corning, grade PMX-0930.

[0078] Vinyl-modified potassium hexatitanate whisker-1: Diameter 1.5 μm, length 39 μm, aspect ratio 26, vinyl mass percentage 0.05 wt%.

[0079] Vinyl-modified potassium hexatitanate whisker-2: Diameter 1.5 μm, length 39 μm, aspect ratio 26, vinyl mass percentage 0.1 wt%.

[0080] Vinyl-modified potassium hexatitanate whisker-3: Diameter 1.5 μm, length 39 μm, aspect ratio 26, vinyl mass percentage 0.2 wt%.

[0081] Vinyl-modified potassium hexatitanate whisker-4: Diameter 1.5 μm, length 39 μm, aspect ratio 26, vinyl mass percentage 0.01 wt%.

[0082] Vinyl-modified potassium hexatitanate whisker-5: Diameter 1.5 μm, length 39 μm, aspect ratio 26, vinyl mass percentage 0.005 wt%.

[0083] Vinyl-modified potassium hexatitanate whisker-6: Diameter 1.5 μm, length 39 μm, aspect ratio 26, vinyl mass percentage 0.3 wt%.

[0084] Vinyl-modified potassium hexatitanate whisker-7: Diameter 2 μm, length 100 μm, aspect ratio 50, vinyl mass percentage 0.05 wt%.

[0085] Vinyl-modified potassium hexatitanate whisker-8: Diameter 1 μm, length 10 μm, aspect ratio 10, vinyl mass percentage 0.05 wt%.

[0086] Vinyl-modified potassium hexatitanate whisker-9: Diameter 0.5 μm, length 50 μm, aspect ratio 100, vinyl mass percentage 0.05 wt%.

[0087] Among them, the preparation method of the vinyl-modified potassium hexatitanate whisker-1 is as follows: Potassium carbonate and metatitanic acid are mixed with water in a molar ratio of 5:1 to form a slurry with a solid content of 20%. After pressure filtration, it is dried in a forced-air oven, pulverized, first heated to 1100 °C at a heating rate of 300 °C / h, sintered for 2 h, and then cooled to 700 °C at a cooling rate of 100 °C / h and sintered for 1.5 h to obtain a precursor. The precursor is added to ethanol, stirred evenly, then vinyltris(2-methoxyethoxy)silane and water are added, mixed evenly, ball-milled at a speed of 35 rpm for 90 min, and screened to obtain vinyl-modified potassium hexatitanate whisker-1. The vinyltris(2-methoxyethoxy)silane is 0.5% of the mass of the precursor, and the amounts of ethanol and water are not limited.

[0088] The difference between the preparation methods of vinyl-modified potassium hexatitanate whiskers-2 to 6 and vinyl-modified potassium hexatitanate whisker-1 lies in that by changing the addition amount of vinyltris(2-methoxyethoxy)silane, the content of vinyl is further changed.

[0089] The difference between the preparation methods of vinyl-modified potassium hexatitanate whiskers-7 to 9 and vinyl-modified potassium hexatitanate whisker-1 lies in that by changing the sintering parameters and ball-milling parameters, the aspect ratio is further changed.

[0090] Potassium hexatitanate whiskers, the preparation method is as follows: Potassium carbonate and metatitanic acid are mixed with water in a molar ratio of 5:1 to form a slurry with a solid content of 20%. After pressure filtration, it is dried in a forced-air oven, pulverized, first heated to 1100 °C at a heating rate of 300 °C / h, sintered for 2 h, and then cooled to 700 °C at a cooling rate of 100 °C / h and sintered for 1.5 h to obtain potassium hexatitanate whiskers.

[0091] Amino-modified potassium hexatitanate whiskers, the preparation method is as follows: Potassium carbonate and metatitanic acid are mixed with water in a molar ratio of 5:1 to form a slurry with a solid content of 20%. After pressure filtration, it is dried in a forced-air oven, pulverized, first heated to 1100 °C at a heating rate of 300 °C / h, sintered for 2 h, and then cooled to 700 °C at a cooling rate of 100 °C / h and sintered for 1.5 h to obtain a precursor. The precursor is added to ethanol, stirred evenly, then γ-aminopropyltriethoxysilane and water are added, mixed evenly, ball-milled at a speed of 35 rpm for 90 min, and screened to obtain γ-aminopropyltriethoxysilane.

[0092] Calcium sulfate whiskers: Fengzhu New Materials, NP-M02-I30.

[0093] Hydrogen-containing silicone oil: Hydrogen-containing silicone oil: Guangdong Chenxi New Materials Technology Co., Ltd., brand CX-351H (hydrogen content = 1%).

[0094] Hollow microspheres-1: Hollow glass microspheres, density is 0.125 g / cm 3, the average particle size of the hollow microspheres is 65 μm, 3M Company, grade K1.

[0095] Hollow microspheres - 2: Hollow glass microspheres, with a density of 0.38 g / cm 3 , the average particle size of the hollow microspheres is 35 μm, 3M Company, grade G38XHS.

[0096] Hollow microspheres - 3: Hollow glass microspheres, with a density of 0.6 g / cm 3 , the average particle size of the hollow microspheres is 18 μm, 3M Company, grade iM30K.

[0097] Wollastonite: The average particle size is 65 μm, commercially available conventionally.

[0098] Catalyst: Platinum catalyst, commercially available conventionally.

[0099] Benzotriazole: Commercially available conventionally.

[0100] Nano - iron oxide: Commercially available conventionally.

[0101] Silica gel flame retardant: Silica gel flame retardant Doher - 117, Dongguan Doer New Materials.

[0102] Silicate aluminates flame retardant: Flame retardant Doher - 8006, Dongguan Doer New Materials.

[0103] Inhibitor: 1 - Ethynyl - 1 - cyclohexanol, commercially available conventionally.

[0104] Unless otherwise specified, the component raw materials used in each example and comparative example of the present invention are all commercially available raw materials, and the component raw materials used in each parallel experiment are of the same kind.

[0105] Examples 1 - 18, Comparative Examples 1 - 10

[0106] The formulations of the flame - retardant and heat - insulating silicone rubber compositions of Examples 1 - 18 and Comparative Examples 1 - 10 are shown in Table 1 and Table 2 (all in parts by weight).

[0107] Among them, the preparation methods of the flame - retardant and heat - insulating silicone rubber compositions of Examples 1 - 18 and Comparative Examples 1 - 10 all include the following steps:

[0108] Add vinyl silicone rubber, vinyl - modified potassium hexatitanate whiskers, hollow microspheres, and flame retardant into a planetary mixer, mix evenly at 120 °C, then add hydrogen - containing silicone oil, stir evenly at 30 °C, and finally add additives, stir evenly at 30 °C to obtain a mixture. Press - vulcanize the mixture into a mold at 150 °C using a flat vulcanizer to obtain the flame - retardant and heat - insulating silicone rubber composition.

[0109] Table 1

[0110]

[0111] Table 2

[0112]

[0113]

[0114] Example 19

[0115] A flame retardant and heat insulating material, comprising a flame retardant and heat insulating layer, and a fiberglass cloth and a release film sequentially arranged on at least one surface of the flame retardant and heat insulating layer.

[0116] The fiberglass cloth has a thickness of 0.05 mm.

[0117] The flame retardant and heat insulating layer is a flame retardant and heat insulating silicone rubber composition with a thickness of 4.5 mm.

[0118] The release film has a thickness of 75 μm.

[0119] The preparation method of the flame retardant and heat insulating material is as follows: the release film - fiberglass cloth - flame retardant and heat insulating layer - fiberglass cloth - release film are vulcanized through a calender line at 150 °C for 25 min in a sandwich form to obtain the flame retardant and heat insulating material.

[0120] Test Example

[0121] Thermal conductivity at 25 °C: Measured by Netzsch laser flash apparatus LFA467.

[0122] Thermal conductivity at 200 °C: Measured by Netzsch laser flash apparatus LFA467.

[0123] 25% compression resilience: Measured by Shimadzu universal tensile testing machine.

[0124] Limiting oxygen index: Tested according to GB / T 10707-2008.

[0125] Table 3

[0126]

[0127]

[0128] As can be seen from Table 3, the silicone rubber composition of the present invention has excellent flame retardant and heat insulating effects. Among them, with the increase of temperature, the thermal conductivity of the composition of the present invention shows a negative growth. The composition is very suitable for preparing secondary batteries, especially suitable for preparing flame retardant and heat insulating pads for secondary batteries, effectively blocking the heat radiation generated by the thermal runaway of secondary batteries at high temperature and reducing the risk of thermal runaway.

[0129] Comparing Example 3 with Comparative Examples 3 to 10 shows that in the system of the present invention, the combined use of the vinyl-modified potassium hexatitanate whiskers and hollow glass microspheres of the present invention has a significant synergistic effect, which can effectively improve the flame retardancy, heat insulation performance and mechanical properties of the composition. The absence of any one of them will lead to a significant decrease in performance. If any one of them is replaced with other components, the performance will also decrease significantly.

[0130] Comparing Example 3 with Comparative Examples 1 to 2 shows that by controlling the mass percentage of vinyl in the vinyl-modified potassium hexatitanate whiskers of the present invention to be 0.01-0.2%, the flame retardancy and heat insulation performance are significantly improved.

[0131] Among them, in Examples 1 to 4, the weight ratio of the vinyl-modified potassium hexatitanate whiskers and the hollow glass microspheres was changed alone. By comparison, it can be seen that by controlling the mass ratio of the vinyl-modified potassium hexatitanate whiskers and the hollow glass microspheres to be 1:(1-3), the flame retardancy and heat insulation performance are further improved.

[0132] Among them, in Example 3 and Examples 5 to 7, the weight ratio of the sum of the weights of the vinyl-modified potassium hexatitanate whiskers and the hollow microspheres to the vinyl silicone rubber was changed alone. By comparison, it can be seen that by controlling the weight ratio of the sum of the weights of the vinyl-modified potassium hexatitanate whiskers and the hollow microspheres to the vinyl silicone rubber to be (0.4-0.5):1, it is further improved.

[0133] Comparing Example 3 with Examples 9 to 10 shows that the vinyl silicone rubber prepared by the present invention using 75-85 parts of methyl vinyl silicone oil, 25-35 parts of vinyl silicone resin, 45-55 parts of fumed silica, and 2-4 parts of structural control agent further improves the flame retardancy and heat insulation performance.

[0134] Comparing Example 3 with Examples 11 to 13 shows that by controlling the mass percentage of vinyl in the vinyl-modified potassium hexatitanate whiskers of the present invention to be 0.05-0.1%, the flame retardancy and heat insulation performance are further improved.

[0135] Comparing Example 3 with Examples 14 to 16 shows that by controlling the aspect ratio of the vinyl-modified potassium hexatitanate whiskers to be 26-50, the flame retardancy and heat insulation performance are further improved.

[0136] Comparing Example 3 with Examples 17 to 18 shows that by controlling the density of the hollow microspheres to be 0.125-0.38 g / cm 3 , and the average particle size of the hollow microspheres to be 35-65 μm, the flame retardancy and heat insulation performance are further improved.

[0137] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A flame-retardant and heat-insulating silicone rubber composition, characterized in that, It comprises the following components in parts by weight: 100 parts of vinyl silicone rubber, 1 - 5 parts of hydrogen-containing silicone oil, 5 - 30 parts of vinyl-modified potassium hexatitanate whiskers, 10 - 40 parts of hollow microspheres, 0.7 - 32 parts of flame retardant, and 0.6 - 9 parts of additives; The mass percentage content of vinyl in the vinyl-modified potassium hexatitanate whiskers is 0.01 - 0.2 wt%; The weight ratio of the vinyl-modified potassium hexatitanate whiskers to the hollow microspheres is 1:(1 - 3); The weight ratio of the sum of the weights of the vinyl-modified potassium hexatitanate whiskers and the hollow microspheres to the vinyl silicone rubber is (0.4 - 0.5):1; The vinyl silicone rubber comprises the following components in parts by weight: 75 - 85 parts of methyl vinyl silicone oil, 25 - 35 parts of vinyl silicone resin, 45 - 55 parts of fumed silica, and 2 - 4 parts of structure control agent; The additives include at least one of a heat-resistant agent, a catalyst, and an inhibitor.

2. The flame-retardant and heat-insulating silicone rubber composition according to claim 1, wherein The aspect ratio of the vinyl-modified potassium hexatitanate whiskers is 10 - 100; and / or The diameter of the vinyl-modified potassium hexatitanate whiskers is 0.1 - 5 μm, and the length is 0.2 - 100 μm.

3. The flame-retardant and heat-insulating silicone rubber composition according to any one of claims 1 to 2, characterized in that, The preparation method of the vinyl-modified potassium hexatitanate whiskers comprises the following steps: Mix potassium carbonate, metatitanic acid, and water evenly, filter press, dry, crush, sinter at 1000 - 1200 °C for 1 - 3 h first, and then sinter at 650 - 750 °C for 1 - 2 h to obtain a precursor; Add the precursor and a vinyl coupling agent to a solvent, mix evenly, ball mill, and screen to obtain vinyl-modified potassium hexatitanate whiskers.

4. The flame-retardant and heat-insulating silicone rubber composition according to claim 3, characterized in that, The molar ratio of potassium carbonate to metatitanic acid is 1:(4 - 8); and / or The vinyl coupling agent is 0.1 - 2% of the mass of the precursor; and / or The vinyl coupling agent includes at least one of vinyltris(2-methoxyethoxy)silane, vinyltrimethoxysilane, and vinyltriethoxysilane.

5. The flame-retardant and heat-insulating silicone rubber composition according to claim 1, wherein, The structure control agent includes at least one of hexamethyldisilazane, dimethyldichlorosilane, hydroxy silicone oil, trimethylethoxysilane, vinyltriethoxysilane, hexamethyldisiloxane, and straight-chain heptanol; The viscosity of the methyl vinyl silicone oil at 25 °C is 800 - 1200 mPa·s; The viscosity of the vinyl silicone resin at 25 °C is 800 - 1000 mPa·s.

6. The flame-retardant and heat-insulating silicone rubber composition according to claim 1, wherein, The hollow microspheres include at least one of hollow glass microspheres, aluminosilicate hollow microspheres, alumina hollow microspheres, carbon hollow microspheres, and zirconia hollow microspheres; and / or The density of the hollow microspheres is 0.125~0.38 g / cm 3 , and the average particle size of the hollow microspheres is 35~65 μm.

7. The flame-retardant and heat-insulating silicone rubber composition according to claim 1, wherein The flame retardant includes at least one of silica gel flame retardant, aluminosilicate flame retardant, and nitrogen-containing flame retardant; the nitrogen-containing flame retardant includes at least one of benzotriazole, 1-hydroxybenzotriazole, and 1-(trimethylsilyl)benzotriazole.

8. The flame-retardant and heat-insulating silicone rubber composition according to claim 1, wherein The heat-resistant agent includes one or more of nano silver powder, nano copper powder, nano iron oxide, nano copper oxide, nano cerium oxide, and polyphenylene sulfide; The catalyst includes at least one of chloroplatinic acid, chloroplatinic acid-divinyltetramethylsiloxane complex, chloroplatinic acid-tetrahydrofuran complex, chloroplatinic acid-isopropanol complex, chloroplatinic acid-diethyl phthalate complex, and chloroplatinic acid-dibutyl maleate complex; The inhibitor includes at least one of 3-methyl-1-butyn-3-ol, 3-methyl-1-pentyn-3-ol, 3,5-dimethyl-1-hexyn-3-ol, and 1-ethynyl-1-cyclohexanol.

9. The preparation method of the flame-retardant and heat-insulating silicone rubber composition according to any one of claims 1 to 8, characterized in that, It includes the following steps: Mix vinyl silicone rubber, vinyl-modified potassium hexatitanate whiskers, hollow microspheres, and a flame retardant evenly, then add hydrogen-containing silicone oil and stir evenly. Finally, add an auxiliary agent, stir evenly, and vulcanize and mold to obtain a flame-retardant and heat-insulating silicone rubber composition.

10. A flame-retardant and heat-insulating material, characterized in that, It includes a flame-retardant and heat-insulating layer, a fiber cloth, and a release film sequentially arranged on at least one surface of the flame-retardant and heat-insulating layer; the flame-retardant and heat-insulating layer includes the flame-retardant and heat-insulating silicone rubber composition according to any one of claims 1 to 8.

11. The flame-retardant and heat-insulating material according to claim 10, characterized in that, It satisfies at least one of the following (a) to (d): (a) The fiber cloth includes at least one of a glass fiber cloth, a basalt fiber cloth, and an alumina fiber cloth; (b) The thickness of the flame-retardant and heat-insulating layer is 1 to 10 mm; (c) The thickness of the fiber cloth is 0.02 to 0.1 mm; (d) The thickness of the release film is 50 to 100 μm.

12. Application of the flame-retardant and heat-insulating material according to any one of claims 10 to 11 in a secondary battery.

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