Flame-retardant heat-insulating silicone rubber composition, flame-retardant heat-insulating material and preparation method and application thereof

Abstract

The invention discloses a flame-retardant heat-insulating silicone rubber composition, a flame-retardant heat-insulating material as well as a preparation method and application thereof, and belongs to the technical field of high polymer materials, the flame-retardant heat-insulating silicone rubber composition 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 a flame retardant and 0.6-9 parts of an auxiliary agent; the length-diameter ratio of the vinyl modified potassium hexatitanate whisker is 10 to 100. The vinyl silicone rubber is used as a matrix, under the combined action of the hydrogen-containing silicone oil, the vinyl modified potassium hexatitanate whiskers, the hollow microspheres and the flame retardant, the flame-retardant and heat-insulating effects of the composition are effectively improved, and the composition is very suitable for preparing a secondary battery, especially suitable for preparing a flame-retardant and heat-insulating pad of the secondary battery, and has a good application prospect. And heat radiation generated by thermal runaway high temperature of the secondary battery is effectively blocked, and the risk of thermal runaway is reduced.

Description

Technical Field

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

[0002] At present, new energy electric vehicles mainly use lithium-ion batteries as power batteries. Under harsh conditions, battery thermal runaway is the primary safety issue for electric vehicles. Power batteries are composed of multiple cells. When the cells are squeezed, deformed, punctured, overcharged, etc., the temperature is too high, causing the battery to thermally run away, and eventually cause the electric vehicle to catch fire and explode. Battery thermal runaway is an important issue in the electric vehicle industry. The new national standard requires that after a battery cell thermally runs away, the battery system will not shut down or explode within five minutes, leaving safe escape time for the occupants. In order to ensure that the power battery does not thermally run away, it is often necessary to use thermal insulation materials to prevent the thermal runaway cells from transferring heat to the surrounding cells.

[0003] Commonly used power battery thermal insulation materials include foam, plastic foam, ultra-fine glass wool, high-silica wool, vacuum insulation panels, silica aerogel, etc. Aerogel insulation materials are currently the main ones, but aerogel has disadvantages such as easy powdering and slag falling, low compressive strength, poor adhesion, and high price.

[0004] Potassium hexatitanate whiskers were originally developed by DuPont for use as aviation high-temperature thermal insulation materials. They have a negative temperature coefficient, with a thermal conductivity of 0.089W / (mK) at room temperature, 0.038W / (mK) at 530°C, and only 0.017W / (mK) at 800°C. They also have excellent infrared ray reflection properties. In addition, potassium hexatitanate whiskers also have excellent electrical insulation, high temperature resistance, acid and alkali resistance, friction resistance, low hardness, and are moderately priced, making them an ideal thermal insulation material. However, potassium hexatitanate whiskers have the disadvantages of poor water resistance and easy oxidation at high temperatures. When potassium hexatitanate whiskers are filled in solid silicone rubber, their room temperature thermal conductivity is often greater than 0.15W / (mK), which makes it difficult to meet the current lightweight and thermal insulation requirements of new energy vehicle batteries.

[0005] In view of this, this application is filed. Summary of the invention

[0006] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a flame retardant and thermal insulation silicone rubber composition, a flame retardant and thermal insulation material, and a preparation method and application thereof. The composition has excellent flame retardant and thermal insulation effects. The composition is very suitable for preparing secondary batteries, especially for preparing flame retardant and thermal insulation pads for secondary batteries, which can effectively block the heat radiation generated by the high temperature of thermal runaway of the secondary battery and reduce the risk of thermal runaway.

[0007] To achieve the above-mentioned 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 retardants, and 0.6 to 9 parts of additives;

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

[0009] The present invention creatively combines the above-mentioned raw materials, takes vinyl silicone rubber as the matrix, and effectively improves the flame retardant and heat-insulating effect of the composition under the joint action of hydrogenated silicone oil, vinyl-modified potassium hexatitanate whiskers, hollow microspheres, and flame retardants. The composition is very suitable for preparing secondary batteries, especially for preparing flame retardant and heat-insulating pads for secondary batteries, which can effectively block the heat radiation generated by the high temperature of thermal runaway of the secondary battery and reduce 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 friction resistance. After being modified with vinyl, the shortcomings of the potassium hexatitanate whiskers such as hydrolysis resistance and high-temperature oxidation are effectively improved, and the stability of the potassium hexatitanate whiskers is guaranteed. After being modified with vinyl, the compatibility and dispersibility of the potassium hexatitanate whiskers in the system are effectively improved, so that the potassium hexatitanate whiskers can be grafted on silicone rubber in a specific form, effectively improving the crosslinking density, improving the processing performance, and improving the fluidity of the rubber compound; the hollow microspheres can effectively reduce the material density and thermal conductivity. coefficient, ensuring the thermal insulation performance and lightweight of the product, and based on the excellent compressive strength of the hollow microspheres, it can effectively improve the compressive strength of the material and block the heat generated instantly by the secondary battery to avoid thermal runaway. Among them, the hollow microspheres can further reduce the overall thermal conductivity of the potassium hexatitanate whiskers in the composition, and further improve the shortcomings of the potassium hexatitanate whiskers such as poor water resistance and easy oxidation at high temperature, while retaining the application characteristics of the negative temperature thermal conductivity of the potassium hexatitanate whiskers. Under the synergistic effect of the two, the flame retardancy and thermal insulation of the composition are effectively improved, so that the thermal conductivity of the composition shows a negative growth as the temperature increases.

[0011] The present invention controls the vinyl content of the vinyl-modified potassium hexatitanate whisker to be 0.01-0.2wt%, so that the vinyl-modified potassium hexatitanate whisker partially participates in the crosslinking of silicone rubber to form a crosslinking network, and partially forms a filling network with hollow microspheres, thereby improving the compatibility and dispersibility in the system, avoiding agglomeration, and effectively improving the flame retardant and heat-insulating effects of the composition.

[0012] As an implementation scheme of the present application, the mass percentage of vinyl in the vinyl-modified potassium hexatitanate whisker is 0.05-0.1wt%. Especially when it is controlled within this range, a cross-linked filling network can be better formed to avoid excessive cross-linking density.

[0013] Wherein, in the flame retardant and heat insulating silicone rubber composition of the present invention, the mass percentage 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 of the vinyl silicone rubber is 50-75%.

[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 of the vinyl silicone rubber is 52-73%.

[0016] As an implementation scheme of the present application, the aspect ratio of the vinyl-modified potassium hexatitanate whisker is 10 to 100; by controlling the aspect ratio of the vinyl-modified potassium hexatitanate whisker to 10 to 100, the present invention can improve the dispersibility and compatibility of the vinyl-modified potassium hexatitanate whisker in the system, more effectively increase the cross-linking density, form a stronger and denser cross-linked network structure, effectively reduce the thermal conductivity of the composition, improve the mechanical properties, and at the same time form a dense filling network 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 whisker is 26-50.

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

[0019] As an embodiment of the present application, the method for preparing the vinyl-modified potassium hexatitanate whisker comprises the following steps:

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

[0021] The precursor and the vinyl coupling agent are added into the solvent, mixed evenly, and ball-milled to obtain the 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 shortcomings of potassium hexatitanate whiskers such as poor water resistance and easy oxidation at high temperature, so that they are evenly dispersed in the composition to 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 titanic acid is 1:(4-8).

[0024] By controlling the ball milling parameters and sintering parameters, the diameter and length of the whiskers can be adjusted, thereby controlling the aspect ratio.

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

[0026] Wherein, 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 accounts for 0.1-2% of the mass of the precursor, and the content of vinyl is controlled by controlling the mass ratio of the vinyl coupling agent to the precursor.

[0028] It should be noted that, in the present invention, the length and diameter of the vinyl-modified potassium hexatitanate whiskers are tested by microscopy: 100 vinyl-modified potassium hexatitanate whisker samples are placed under a microscope for observation, the lengths and diameters of all vinyl-modified potassium hexatitanate whiskers in the sample 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] The mass percentage of vinyl in the vinyl-modified potassium hexatitanate whiskers was measured by near infrared method.

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

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

[0032] The structure control agent includes at least one of hexamethyldisilazane, dimethyldichlorosilane, hydroxy silicone oil, trimethylethoxysilane, vinyltriethoxysilane, hexamethyldisiloxane, and linear 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 filling network structure, increases the interaction force between molecular chains, avoids excessive density of cross-linking points, avoids stress concentration, and effectively improves the flame retardant and heat-insulating effects of the composition.

[0034] Among them, the present invention is not limited to the preparation method of vinyl silicone rubber. Those skilled in the art can prepare vinyl silicone rubber from methyl vinyl silicone oil, vinyl silicone resin, fumed silica and structure control agent according to the formula disclosed by the present invention and conventional technical means in the art.

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

[0036] More specifically, the preparation method of the vinyl silicone rubber is as follows: methyl vinyl silicone oil, vinyl silicone resin, fumed silica and a structure control agent are added to a kneader, and the kneading frequency is controlled at 35-50 Hz at 25-45° C., a cold cycle is started, and a vacuum degree is maintained at ≤-0.098 MPa until the rubber material is kneaded and formed; after the rubber material is formed, a hot cycle is started, the temperature is controlled at 150-160° C., a vacuum degree is maintained at ≤-0.098 MPa, hot kneading is performed for 2-4 hours, and then the temperature is lowered to room temperature, and the material is discharged 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 to 1200 mPa·s.

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

[0039] As an embodiment of the present application, the hollow microspheres include at least one of hollow glass microspheres, hollow aluminum silicate microspheres, hollow aluminum oxide microspheres, hollow carbon microspheres, and hollow zirconium oxide microspheres.

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

[0041] As an implementation scheme of the present application, the weight ratio of the vinyl-modified potassium hexatitanate whiskers and hollow microspheres is 1:(1-3). By controlling the mass ratio of the two within a certain range, the shortcomings of the potassium hexatitanate whiskers, such as poor water resistance and easy oxidation at high temperatures, can be effectively improved. At the same time, the vinyl-modified potassium hexatitanate whiskers and hollow microspheres can be better filled in the system, effectively improving the flame retardant and heat insulating properties.

[0042] As an implementation scheme of the present application, the weight ratio of the sum of the weights of the vinyl-modified potassium hexatitanate whiskers and hollow microspheres to the vinyl silicone rubber is (0.4-0.5):1. By controlling the vinyl-modified potassium hexatitanate whiskers and 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 hollow microspheres in the system are improved. At the same time, the formation of a dense cross-linked network structure and a filling network structure is promoted, thereby more effectively improving the flame retardant and thermal insulation properties.

[0043] As an embodiment of the present application, the flame retardant includes at least one of a silica gel flame retardant, a silicate 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 implementation scheme of the present application, the flame retardant includes a silicone flame retardant, an aluminosilicate flame retardant and a nitrogen-containing flame retardant. The mass ratio of the silicone flame retardant, the aluminosilicate flame retardant and the nitrogen-containing flame retardant is (0.1-2): (0.3-28): (0.3-2). By controlling the masses of the three within this range, in the specific system of the present invention, the silicone flame retardant has a good flame retardant effect, the silicate flame retardant has a good coordination effect with the silicone system, and can effectively bond the amorphous silica produced by the thermal decomposition of silicone rubber at high temperature to form a protective outer layer. The nitrogen-containing flame retardant forms a shielding layer at high temperature under the action of a catalyst, which has 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 nano silver powder, nano copper powder, nano iron oxide, nano copper oxide, nano cerium oxide, 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, 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 mineral powder, and suitable mineral powder includes but is 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 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 ester, hyperbranched amide and combinations thereof.

[0054] The flame retardant and heat insulating silicone rubber composition of the present invention may include a weathering agent, and 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 a UV absorber. Suitable UV absorbers include but are not limited to hydroxybenzophenones, benzotriazoles, hydroxybenzotriazines, cyanoacrylates, nanoscale inorganic materials (eg, 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, comprising the following steps:

[0058] Vinyl silicone rubber, vinyl modified potassium hexatitanate whisker, hollow microspheres and flame retardant are mixed evenly, hydrogen-containing silicone oil is added and stirred evenly, and finally an auxiliary agent is added, stirred evenly, and vulcanized to obtain a flame retardant and heat-insulating silicone rubber composition.

[0059] The third aspect of the present application provides a use of the flame retardant and heat insulating silicone rubber composition in the preparation of a flame retardant and heat insulating material.

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

[0061] As an implementation scheme 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 glass fiber cloth, basalt fiber cloth and alumina fiber cloth;

[0063] (b) the thickness of the flame retardant heat insulation layer is 1 to 10 mm;

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

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

[0066] A fifth aspect of the present application provides an application of a flame retardant and heat insulating material in a secondary battery.

[0067] The beneficial effects of the present invention are as follows: the present invention uses vinyl silicone rubber as a matrix, and under the joint action of hydrogenated silicone oil, vinyl-modified potassium hexatitanate whiskers, hollow microspheres, and flame retardants, effectively improves the flame retardant and heat-insulating effect of the composition. The composition is very suitable for preparing secondary batteries, especially for preparing flame retardant and heat-insulating pads for secondary batteries, and effectively blocks the heat radiation generated by high temperature of thermal runaway of secondary batteries, thereby reducing the risk of thermal runaway. DETAILED DESCRIPTION

[0068] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application are described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present application.

[0069] In the present application, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features.

[0070] In this application, when it comes to numerical ranges, unless otherwise specified, the above numerical ranges are deemed to be continuous and include the minimum and maximum values ​​of the range, as well as each value between such minimum and maximum values. Further, when a range refers to an integer, each integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe features or characteristics, the ranges can be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges included therein.

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

[0072] Vinyl silicone rubber-1, the preparation method is as follows: according to weight parts, 80 parts of methyl vinyl silicone oil, 30 parts of vinyl silicone resin, 50 parts of fumed silica and 3 parts of hydroxy silicone oil are added to a kneader, at 40°C, the kneading frequency is controlled at 40Hz, the cold cycle is started, and the vacuum degree is maintained at ≤-0.098MPa 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 at ≤-0.098MPa, hot kneading is carried out for 3 hours, and then the temperature is reduced to room temperature, and the material is discharged to obtain vinyl silicone rubber-1.

[0073] Vinyl silicone rubber-2, the preparation method is as follows: according to weight parts, 60 parts of methyl vinyl silicone oil, 50 parts of vinyl silicone resin, 40 parts of fumed silica and 6 parts of hydroxy silicone oil are added to a kneader, at 40°C, the kneading frequency is controlled at 40Hz, the cold cycle is started, and the vacuum degree is maintained at ≤-0.098MPa 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 at ≤-0.098MPa, hot kneading is carried out for 3 hours, and then the temperature is reduced to room temperature, and the material is discharged to obtain vinyl silicone rubber-2.

[0074] Vinyl silicone rubber-3, the preparation method is as follows: according to weight parts, 100 parts of methyl vinyl silicone oil, 20 parts of vinyl silicone resin, 60 parts of fumed silica and 1 part of hydroxy silicone oil are added into a kneader, at 40°C, the kneading frequency is controlled at 40Hz, the cold cycle is started, and the vacuum degree is maintained at ≤-0.098MPa 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 at ≤-0.098MPa, hot kneading is carried out for 3 hours, and then the temperature is reduced to room temperature, and the material is discharged to obtain vinyl silicone rubber-3.

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

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

[0077] Hydroxy silicone oil: Dow Corning, brand 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, metatitanic acid and water are mixed in a molar ratio of 5:1 to form a slurry with a solid content of 20%, filtered, dried in a blast oven, and crushed. The mixture is first heated to 1100°C at a heating rate of 300°C / h, sintered for 2h, and then cooled to 700°C at a cooling rate of 100°C / h and sintered for 1.5h to obtain a precursor; the precursor is added to ethanol, stirred evenly, and then vinyl tris(2-methoxyethoxy)silane and water are added, mixed evenly, ball milled at a speed of 35rpm for 90min, and sieved to obtain vinyl-modified potassium hexatitanate whisker-1, wherein the vinyl tris(2-methoxyethoxy)silane is 0.5% of the mass of the precursor, and the amount of ethanol and water is not limited.

[0088] The difference between the preparation methods of vinyl-modified potassium hexatitanate whiskers-2 to 6 and vinyl-modified potassium hexatitanate whiskers-1 is that the vinyl content is changed by changing the amount of vinyl tris(2-methoxyethoxy)silane added.

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

[0090] Potassium hexatitanate whiskers are prepared by mixing potassium carbonate, metatitanic acid and water in a molar ratio of 5:1 into a slurry with a solid content of 20%, filtering, drying in a blast oven, and crushing. The mixture is first heated to 1100°C at a heating rate of 300°C / h, sintered for 2h, and then cooled to 700°C at a cooling rate of 100°C / h and sintered for 1.5h to obtain potassium hexatitanate whiskers.

[0091] The amino-modified potassium hexatitanate whiskers are prepared by mixing potassium carbonate, metatitanic acid and water in a molar ratio of 5:1 into a slurry with a solid content of 20%, filtering, drying in a forced air oven, and crushing. The mixture is first heated to 1100°C at a heating rate of 300°C / h, sintered for 2h, and then cooled to 700°C at a cooling rate of 100°C / h and sintered for 1.5h to obtain a precursor. The precursor is added to ethanol and stirred evenly, and then γ-aminopropyltriethoxysilane and water are added, mixed evenly, ball-milled at a rotation speed of 35rpm for 90min, and sieved to obtain γ-aminopropyltriethoxysilane.

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

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

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

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

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

[0097] Wollastonite: average particle size 65 μm, commonly available in the market.

[0098] Catalyst: Platinum catalyst, commonly available in the market.

[0099] Benzotriazole: commonly available on the market.

[0100] Nano iron oxide: commonly available in the market.

[0101] Silicone flame retardant: Silicone flame retardant Doher-117, Dongguan Doher New Materials.

[0102] Aluminosilicate flame retardant: flame retardant Doher-8006, Dongguan Doher New Materials.

[0103] Inhibitor: 1-ethynyl-1-cyclohexanol, commonly available in the market.

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

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

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

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

[0108] Add vinyl silicone rubber, vinyl modified potassium hexatitanate whiskers, hollow microspheres and flame retardants into a planetary mixer, mix evenly at 120°C, add hydrogenated silicone oil, stir evenly at 30°C, finally add an auxiliary agent, stir evenly at 30°C to obtain a mixture, and vulcanize the mixture by flat plate compression molding at 150°C using a flat plate vulcanizer to obtain a flame retardant and heat-insulating silicone rubber composition.

[0109] Table 1

[0110]

[0111] Table 2

[0112]

[0113]

[0114] Embodiment 19

[0115] A flame retardant heat-insulating material comprises a flame retardant heat-insulating layer and a glass fiber cloth and a release film which are sequentially arranged on at least one surface of the flame retardant heat-insulating layer.

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

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

[0118] The thickness of the release film is 75 μm.

[0119] The preparation method of the flame retardant heat insulating material is as follows: vulcanizing the release film-glass fiber cloth-flame retardant heat insulating layer-glass fiber cloth-release film in a sandwich form through a 150° C. calendering line for 25 minutes to obtain the flame retardant heat insulating material.

[0120] Test Case

[0121] Thermal conductivity at 25℃: tested using NETZSCH laser flash meter LFA467.

[0122] Thermal conductivity at 200℃: tested using NETZSCH laser flash meter LFA467.

[0123] 25% compression rebound force: tested using Shimadzu universal tensile testing machine.

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

[0125] Table 3

[0126]

[0127]

[0128] It can be seen from Table 3 that the silicone rubber composition of the present invention has excellent flame retardant and heat-insulating effects, wherein the thermal conductivity of the composition of the present invention shows a negative growth as the temperature increases, and the composition is very suitable for preparing secondary batteries, especially for preparing flame retardant and heat-insulating pads for secondary batteries, which can effectively block the heat radiation generated by the high temperature of thermal runaway of the secondary battery and reduce the risk of thermal runaway.

[0129] By comparing Example 3 with Comparative Examples 3 to 10, it can be seen that in the system of the present invention, the combination of the vinyl-modified potassium hexatitanate whiskers and hollow glass microspheres described in the present invention has a significant synergistic effect, which can effectively improve the flame retardant and heat insulating properties and mechanical properties of the composition. The lack of any one of them will lead to a significant decrease in performance. If any one of them is replaced by other components, the performance will also be significantly reduced.

[0130] By comparing Example 3 with Comparative Examples 1-2, it can be seen that the flame retardant and heat insulating properties of the present invention are significantly improved by controlling the mass percentage of vinyl in the vinyl-modified potassium hexatitanate whiskers to 0.01-0.2%.

[0131] Among them, Examples 1 to 4 simply change the weight ratio of vinyl-modified potassium hexatitanate whiskers and hollow glass microspheres. By comparison, it can be seen that by controlling the mass ratio of vinyl-modified potassium hexatitanate whiskers and hollow glass microspheres to 1: (1 to 3), the flame retardant and thermal insulation properties are further improved.

[0132] Among them, Examples 3 and 5 to 7 simply changed the weight ratio of the sum of the weights of the vinyl-modified potassium hexatitanate whiskers and hollow microspheres to the vinyl silicone rubber. 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 hollow microspheres to the vinyl silicone rubber to (0.4 to 0.5): 1, the efficiency is further improved.

[0133] By comparing Examples 3 with 9 to 10, it can be seen that the vinyl silicone rubber prepared by the present invention using 75 to 85 parts of methyl vinyl silicone oil, 25 to 35 parts of vinyl silicone resin, 45 to 55 parts of fumed silica, and 2 to 4 parts of structure control agent further improves the flame retardant and heat insulating properties.

[0134] By comparing Example 3 with Examples 11 to 13, it can be seen that the flame retardant and heat insulating properties of the present invention are further improved by controlling the mass percentage of vinyl in the vinyl-modified potassium hexatitanate whiskers to 0.05 to 0.1%.

[0135] By comparing Example 3 with Examples 14 to 16, it can be seen that the flame retardant and heat insulating properties of the present invention are further improved by controlling the aspect ratio of the vinyl-modified potassium hexatitanate whiskers to be 26 to 50.

[0136] Comparing Example 3 with Examples 17 to 18, it can be seen that the density of the hollow microspheres is controlled to be 0.125 to 0.38 g / cm 3 The average particle size of the hollow microspheres is 35 to 65 μm, which further improves the flame retardant and heat insulating properties.

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

Claims

1. A flame retardant and heat insulating silicone rubber composition, characterized in that: The invention comprises 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 retardants, and 0.6 to 9 parts of additives; The mass percentage of vinyl in the vinyl-modified potassium hexatitanate whisker is 0.01-0.2 wt %.

2. The flame retardant and heat insulating silicone rubber composition according to claim 1, characterized in that: The aspect ratio of the vinyl modified potassium hexatitanate whisker is 10 to 100; and / or The vinyl modified potassium hexatitanate whisker has a diameter of 0.1 to 5 μm and a length of 0.2 to 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 method for preparing the vinyl-modified potassium hexatitanate whisker comprises the following steps: Mix potassium carbonate, metatitanic acid and water evenly, filter press, dry, crush, sinter at 1000-1200°C for 1-3h, and then sinter at 650-750°C for 1-2h to obtain a precursor; The precursor and the vinyl coupling agent are added into the solvent, mixed evenly, ball-milled, and sieved to obtain the 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 vinyl tri(2-methoxyethoxy)silane, vinyl trimethoxysilane and vinyl triethoxysilane.

5. The flame retardant and heat insulating silicone rubber composition according to claim 1, characterized in that: The vinyl silicone rubber comprises the following components in parts by weight: 75 to 85 parts of methyl vinyl silicone oil, 25 to 35 parts of vinyl silicone resin, 45 to 55 parts of fumed silica, and 2 to 4 parts of a structure control agent; The structure control agent includes at least one of hexamethyldisilazane, dimethyldichlorosilane, hydroxy silicone oil, trimethylethoxysilane, vinyltriethoxysilane, hexamethyldisiloxane, and linear heptanol; The viscosity of the methyl vinyl silicone oil at 25° C. is 800 to 1200 mPa·s; The viscosity of the vinyl silicone resin at 25° C. is 800 to 1000 mPa·s.

6. The flame retardant and heat insulating silicone rubber composition according to claim 1, characterized in that: The hollow microspheres include at least one of hollow glass microspheres, hollow aluminum silicate microspheres, hollow aluminum oxide microspheres, hollow carbon microspheres, and hollow zirconium oxide microspheres; and / or The density of the hollow microspheres is 0.125 to 0.38 g / cm 3 The average particle size of the hollow microspheres is 35 to 65 μm.

7. The flame retardant and heat insulating silicone rubber composition according to claim 1, characterized in that: The weight ratio of the vinyl modified potassium hexatitanate whiskers to the hollow microspheres is 1:(1-3); and / or The weight ratio of the sum of the weights of the vinyl-modified potassium hexatitanate whiskers and hollow microspheres to the vinyl silicone rubber is (0.4-0.5):

1.

8. The flame retardant and heat insulating silicone rubber composition according to claim 1, characterized in that: 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.

9. The flame retardant and heat insulating silicone rubber composition according to claim 1, characterized in that: The auxiliary agent includes at least one of a heat-resistant agent, a catalyst, and an inhibitor; 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 comprises 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.

10. The method for preparing the flame retardant and heat insulating silicone rubber composition according to any one of claims 1 to 9, characterized in that: The following steps are involved: Vinyl silicone rubber, vinyl modified potassium hexatitanate whisker, hollow microspheres and flame retardant are mixed evenly, hydrogen-containing silicone oil is added and stirred evenly, and finally an auxiliary agent is added, stirred evenly, and vulcanized to obtain a flame retardant and heat-insulating silicone rubber composition.

11. A flame retardant heat insulating material, characterized in that: It comprises a flame retardant heat-insulating layer and a fiber cloth and a release film arranged in sequence on at least one surface of the flame retardant heat-insulating layer; the flame retardant heat-insulating layer comprises the flame retardant heat-insulating silicone rubber composition according to any one of claims 1 to 9.

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

13. Use of the flame retardant and heat insulating material according to any one of claims 11 to 12 in secondary batteries.

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