White low-density flame-retardant silicone rubber as well as preparation method and application thereof

Abstract

The invention relates to a novel rubber material, in particular to white low-density flame-retardant silicone rubber as well as a preparation method and application thereof. The white low-density flame-retardant silicone rubber comprises first vinyl-terminated polysiloxane, second vinyl-terminated polysiloxane, hydrogen-containing polysiloxane, an acyloxy silane coupling agent, a platinum catalyst, an alkynol inhibitor, an inorganic flame-retardant filler, white carbon black and a synergistic flame-retardant system. The white low-density flame-retardant silicone rubber disclosed by the invention is liquid silicone rubber and has the advantages of white color, low density, excellent flame-retardant effect, good processability and the like.

Description

Technical Field

[0001] This invention relates to a novel rubber material, and more particularly to a white, low-density, flame-retardant silicone rubber, its preparation method, and its applications. Background Technology

[0002] To address the issues of lightweighting electric vehicles and the potential combustion hazards of power batteries, the silicone rubber material used for sealing the battery pack must have low density and excellent flame-retardant properties.

[0003] Flame-retardant silicone rubber is a typical polymer composite material. Traditional flame-retardant silicone rubber materials involve adding large amounts of inorganic powders such as metal hydroxides and carbonates. The addition of large amounts of powder often results in high viscosity, poor processability, and excessively high density, failing to meet current vehicle lightweighting requirements. Meanwhile, currently popular low-density foam materials have poor strength and inadequate flame-retardant properties. Furthermore, black flame-retardant silicone rubber is predominantly available, which limits applications with specific color requirements.

[0004] Therefore, there is an urgent need to develop a new type of white, low-density, flame-retardant silicone rubber. Summary of the Invention

[0005] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a white low-density flame-retardant silicone rubber, its preparation method and application. The flame-retardant silicone rubber of this invention is white and low-density, has excellent flame-retardant effect and good processability, thereby solving the problems in the prior art.

[0006] The technical solution of this invention is: This invention provides a white low-density flame-retardant silicone rubber, which comprises the following components in parts by weight: 10 to 50 parts of a first vinyl-terminated polysiloxane; 10 to 50 parts of a second vinyl-terminated polysiloxane; 0.5 to 5 parts of hydrogen-containing polysiloxane; Acyloxysilane coupling agent, 0.01 ~ 0.1 parts; Platinum catalyst 0.05 ~ 0.5 parts; Alkyne inhibitors, 0.01 ~ 0.1 parts; 20-80 parts of inorganic flame-retardant filler; 1 to 5 parts of silica; 10-30 parts of the synergistic flame retardant system; Wherein, the first vinyl-terminated polysiloxane has a viscosity of 2000~5000 mpa.s at 25°C, and the second vinyl-terminated polysiloxane has a viscosity of 10000~100000 mpa.s at 25°C; the inorganic flame-retardant filler is selected from aluminum hydroxide, and the synergistic flame-retardant system is selected from one or more of hydrotalcite, electrolytic zinc oxide, and zinc borate.

[0007] This invention also provides a method for preparing white low-density flame-retardant silicone rubber, the method comprising the following steps: 1) Mix and stir the first vinyl-terminated polysiloxane, the second vinyl-terminated polysiloxane, the hydrogen-containing polysiloxane, the acyloxysilane coupling agent, and the alkynyl alcohol inhibitor to obtain the first mixture; 2) Add inorganic flame retardant filler to the first mixture obtained in step 1) and stir to obtain a second mixture; 3) Add silica and the synergistic flame retardant system to the second mixture obtained in step 2) and stir to obtain the third mixture; 4) Add platinum catalyst to the third mixture obtained in step 3) and stir to obtain a rubber compound; 5) Vacuum the rubber and maintain it for a period of time. Then, open the air to the atmosphere, extrude the prepared rubber material, place it in a mold for vulcanization, and obtain white low-density flame-retardant silicone rubber.

[0008] By adopting the aforementioned technical solution, the beneficial effects of the present invention are: The white low-density flame-retardant silicone rubber of the present invention is a liquid silicone rubber with advantages such as white low density (density less than or equal to 1.31), excellent flame retardant effect (UL-94 V0), and good processability.

[0009] This invention is produced by addition reaction thermal vulcanization. The production process does not produce any irritating odor or harmful substances. It has a fast vulcanization rate and can be deeply cured. It has low viscosity, good processability, and combines flame retardancy, strength and insulation properties. Detailed Implementation

[0010] The following describes in detail the implementation of the white low-density flame-retardant silicone rubber, its preparation method, and its applications provided by the present invention.

[0011] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60~120 and 80~110 are listed for a specific parameter, it is also expected that ranges of 60~110 and 80~120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1~3, 1~4, 1~5, 2~3, 2~4, and 2~5. In this application, unless otherwise stated, the numerical range "a~b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0~5" indicates that all real numbers between "0~5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0012] Through extensive research and exploration, the inventors of this invention have provided a flame-retardant silicone rubber material for use in the enclosure of automotive power batteries. This invention, through the synergistic effect of its components, produces a white, low-density flame-retardant silicone rubber, a liquid silicone rubber, which possesses advantages such as white color, low density, excellent flame-retardant effect, and good processability. Particularly from an environmental perspective, the aluminum hydroxide, zinc borate, and hydrotalcite selected in this invention undergo combustion decomposition to produce water and carbon dioxide, diluting the combustible gases. The byproduct metal oxides, along with electrolytic-grade zinc oxide and silica, form a protective film on the material surface, preventing further oxygen participation in combustion. Simultaneously, the electrolytic-grade zinc oxide captures free radicals generated during the combustion reaction, interrupting flame propagation. This also meets the high material performance and low density requirements of power batteries. Based on this, this application has been completed.

[0013] White low-density flame-retardant silicone rubber This invention provides a white low-density flame-retardant silicone rubber, which comprises a first vinyl-terminated polysiloxane, a second vinyl-terminated polysiloxane, a hydrogen-containing polysiloxane, an acyloxysilane coupling agent, a platinum catalyst, an alkynyl alcohol inhibitor, an inorganic flame-retardant filler, silica, and a synergistic flame-retardant system.

[0014] In the white low-density flame-retardant silicone rubber provided by the present invention, the first vinyl-terminated polysiloxane is 10 to 50 parts and any value between them or any two values. Optionally, the first vinyl-terminated polysiloxane can be, for example, 10 to 30 parts, 30 to 50 parts, 10 to 20 parts, 20 to 30 parts, 30 to 40 parts, or 40 to 50 parts.

[0015] Further, the viscosity of the first vinyl-terminated polysiloxane at 25°C is 2000~5000 mpa.s and any value between them or any two values. Optionally, the viscosity of the first vinyl-terminated polysiloxane at 25°C can be, for example, 2000~3000 mpa.s, 3000~5000 mpa.s, 2000~4000 mpa.s, or 4000~5000 mpa.s.

[0016] The vinyl content in the first vinyl-terminated polysiloxane is 0.1% to 1%. Optionally, the vinyl content in the first vinyl-terminated polysiloxane may be, for example, 0.1% to 0.5%, 0.5% to 1%, 0.1% to 0.3%, 0.3% to 0.5%, 0.5% to 0.8%, or 0.8% to 1%.

[0017] In the white low-density flame-retardant silicone rubber provided by the present invention, the second vinyl-terminated polysiloxane is 10 to 50 parts and any value between them or any two values; optionally, the second vinyl-terminated polysiloxane can be, for example, 10 to 30 parts, 30 to 50 parts, 10 to 20 parts, 20 to 30 parts, 30 to 40 parts, or 40 to 50 parts.

[0018] Further, the viscosity of the second vinyl-terminated polysiloxane at 25°C is 10,000 to 100,000 mPa·s and any value between them or any two values. Optionally, the viscosity of the second vinyl-terminated polysiloxane at 25°C can be, for example, 10,000 to 50,000 mPa·s, 50,000 to 100,000 mPa·s, 10,000 to 30,000 mPa·s, 30,000 to 50,000 mPa·s, 50,000 to 80,000 mPa·s, or 80,000 to 100,000 mPa·s.

[0019] The vinyl content in the second vinyl-terminated polysiloxane is 0.1% to 0.6%. Optionally, the vinyl content in the second vinyl-terminated polysiloxane may be, for example, 0.1% to 0.3%, 0.3% to 0.6%, 0.1% to 0.2%, 0.2% to 0.4%, or 0.4% to 0.6%.

[0020] In the white low-density flame-retardant silicone rubber provided by the present invention, the hydrogen-containing polysiloxane is 0.5 to 5 parts and any value between them or any two values; optionally, the hydrogen-containing polysiloxane may be, for example, 0.5 to 3 parts, 3 to 5 parts, 0.5 to 2 parts, 2 to 3 parts, 3 to 4 parts, or 4 to 5 parts.

[0021] Further, the viscosity of the hydrogen-containing polysiloxane at 25°C is 20-500 mPa·s. Optionally, the viscosity of the hydrogen-containing polysiloxane at 25°C can be, for example, 20-100 mPa·s, 100-300 mPa·s, 300-500 mPa·s, 100-200 mPa·s, 200-300 mPa·s, 300-400 mPa·s, or 400-500 mPa·s. R in the hydrogen-containing polysiloxane is methyl, ethyl, propyl, or butyl. Wherein R refers to the type of alkyl side chain of the hydrogen-containing polysiloxane.

[0022] Further, the hydrogen content of the hydrogen-containing polysiloxane is 0.3% to 1.6%. Optionally, the hydrogen content of the hydrogen-containing polysiloxane can be, for example, 0.3% to 1.0%, 1.0% to 1.6%, 0.3% to 0.8%, 0.8% to 1.2%, or 1.2% to 1.6%.

[0023] In the white low-density flame-retardant silicone rubber provided by the present invention, the acyloxysilane coupling agent is 0.01 to 0.1 parts and any value between them or any two values; optionally, the acyloxysilane coupling agent may be, for example, 0.01 to 0.05 parts, 0.05 to 0.1 parts, 0.01 to 0.03 parts, 0.03 to 0.05 parts, 0.05 to 0.08 parts, or 0.08 to 0.1 parts.

[0024] Furthermore, the acyloxysilane coupling agent is selected from one or more of 3-methacryloyloxypropyltriethoxysilane coupling agent and isopropyl dioleoyloxytitanate coupling agent.

[0025] In the white low-density flame-retardant silicone rubber provided by the present invention, the platinum catalyst is 0.05 to 0.5 parts and any value between them or any two values; optionally, the platinum catalyst may be, for example, 0.05 to 0.1 parts, 0.1 to 0.3 parts, or 0.3 to 0.5 parts.

[0026] Furthermore, the platinum catalyst is a chloroplatinic acid catalyst.

[0027] In the white low-density flame-retardant silicone rubber provided by the present invention, the acetylsalicylic alcohol inhibitor is 0.01 to 0.1 parts and any value between them or any two values; optionally, the acetylsalicylic alcohol inhibitor can be, for example, 0.01 to 0.1 parts; optionally, the acetylsalicylic alcohol inhibitor can be, for example, 0.01 to 0.05 parts, 0.05 to 0.1 parts, 0.01 to 0.03 parts, 0.03 to 0.05 parts, 0.05 to 0.08 parts, or 0.08 to 0.1 parts.

[0028] Furthermore, the alkynol inhibitor is selected from one or more of 3-methyl-1-dodecyn-3-ol curing inhibitor and ethynylcyclohexanol.

[0029] In the white low-density flame-retardant silicone rubber provided by the present invention, the inorganic flame-retardant filler is 20 to 80 parts and any value between them or any two values; optionally, the inorganic flame-retardant filler can be, for example, 20 to 40 parts, 40 to 60 parts, or 60 to 80 parts.

[0030] Furthermore, the inorganic flame-retardant filler is selected from aluminum hydroxide. The average particle size of the inorganic flame-retardant filler is 3-20 micrometers. Optionally, the average particle size of the aluminum hydroxide can be, for example, 3-10 micrometers or 10-20 micrometers. 3-10 micrometer aluminum hydroxide can increase the strength of the material, while smaller particle sizes of aluminum hydroxide will greatly increase the viscosity of the adhesive, thereby reducing processability; 10-20 micrometer aluminum hydroxide can significantly improve the flowability of the adhesive, while using larger particle sizes of powder will damage the strength of the material itself.

[0031] In the white low-density flame-retardant silicone rubber provided by the present invention, the silica is 1 to 5 parts and any value between them or any two values; optionally, the silica can be, for example, 1 to 3 parts, 3 to 5 parts, 1 to 2 parts, 2 to 3 parts, 3 to 4 parts, or 4 to 5 parts.

[0032] Furthermore, the silica is fumed silica produced by gasification. The average particle size of the silica is 10-20 nanometers or any value between them or any two values, and can be selected as 10-15 nanometers or 15-20 nanometers.

[0033] In the white low-density flame-retardant silicone rubber provided by the present invention, the synergistic flame-retardant system is 10 to 30 parts; optionally, the synergistic flame-retardant system can be, for example, 10 to 15 parts, 15 to 20 parts, 20 to 25 parts, or 25 to 30 parts.

[0034] Furthermore, the synergistic flame retardant system is selected from one or more of hydrotalcite, electrolytic zinc oxide, and zinc borate.

[0035] Furthermore, the average particle size of the synergistic flame retardant system is 2 to 20 micrometers and any value between them or any two values, and can be selected as 2 to 10 micrometers, 10 to 20 micrometers, 2 to 5 micrometers, 5 to 10 micrometers, 10 to 15 micrometers, or 15 to 20 micrometers.

[0036] Preparation method of white low-density flame-retardant silicone rubber This invention also provides a method for preparing white low-density flame-retardant silicone rubber, the method comprising the following steps: 1) Mix and stir the first vinyl-terminated polysiloxane, the second vinyl-terminated polysiloxane, the hydrogen-containing polysiloxane, the acyloxysilane coupling agent, and the alkynyl alcohol inhibitor to obtain the first mixture; 2) Add inorganic flame retardant filler to the first mixture obtained in step 1) and stir to obtain a second mixture; 3) Add silica and the synergistic flame retardant system to the second mixture obtained in step 2) and stir to obtain the third mixture; 4) Add platinum catalyst to the third mixture obtained in step 3) and stir to obtain a rubber compound; 5) Vacuum the rubber and maintain it for a period of time. Then, open the air to the atmosphere, extrude the prepared rubber material, place it in a mold for vulcanization, and obtain white low-density flame-retardant silicone rubber.

[0037] In step 1) of this invention, vinyl-terminated polysiloxane with a viscosity of 2000~5000 mpa.s at 25°C, vinyl-terminated polysiloxane with a viscosity of 5000~100000 mpa.s, hydrogen-containing polysiloxane, acyloxysilane coupling agent, and alkynyl alcohol inhibitor are sequentially added to a planetary mixer or high-speed disperser and stirred evenly.

[0038] In step 2) of this invention, a planetary mixer or a high-speed disperser is added and stirred for a time of, for example, 5 to 15 minutes, or optionally 5 to 10 minutes or 10 to 15 minutes.

[0039] In step 3) of this invention, a planetary mixer or a high-speed disperser is added and stirred for a time of, for example, 45-55 minutes, or optionally 45-50 minutes or 50-55 minutes.

[0040] In step 4) of this invention, after ensuring that there is no excess powder in the machine, a platinum catalyst is added and stirred for, for example, 5 to 15 minutes, or 5 to 10 minutes or 10 to 15 minutes.

[0041] In step 5) of this invention, the vacuum is turned on, the gauge pressure is 0.098 MPa, and it is maintained for 20 to 25 minutes.

[0042] In step 5 of this invention, the temperature is raised to 100-150°C and vulcanized for 10-15 minutes.

[0043] The beneficial effects of the present invention will be further illustrated below with reference to the embodiments.

[0044] To make the inventive objectives, technical solutions, and beneficial effects of this invention clearer, the invention is further described in detail below with reference to embodiments. However, it should be understood that the embodiments of this invention are merely for illustrative purposes and not for limiting the invention, and the embodiments are not limited to those given in the specification. Unless otherwise specified, specific experimental or operational conditions in the embodiments were prepared under conventional conditions or according to the conditions recommended by the material supplier.

[0045] Furthermore, it should be understood that the existence of other method steps before or after the combined steps, or the insertion of other method steps between these explicitly mentioned steps, does not preclude the existence of other method steps before or after the combined steps, or the insertion of other method steps between these explicitly mentioned steps, unless otherwise stated. It should also be understood that the combined connection relationship between one or more devices / apparatus mentioned in this invention does not preclude the existence of other devices / apparatus before or after the combined devices / apparatus, or the insertion of other devices / apparatus between these explicitly mentioned devices / apparatus, unless otherwise stated. Moreover, unless otherwise stated, the numbering of each method step is merely a convenient tool for identifying each method step, and not for limiting the order of the method steps or limiting the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention.

[0046] In the following embodiments, unless otherwise specified, all the raw materials of the present invention are commercially available or prepared according to conventional methods in the art.

[0047] 2000 mpa.s of vinyl-terminated polysiloxane was purchased from Zhejiang Runhe Organosilicon New Material Co., Ltd., model RH-Vi320; The 5000 mpa.s vinyl-terminated polysiloxane was purchased from Zhejiang Runhe Organosilicon New Materials Co., Ltd., model RH-Vi304; 20,000 mpa.s of vinyl-terminated polysiloxane was purchased from Zhejiang Runhe Organosilicon New Materials Co., Ltd., model RH-Vi302; The 50,000 mpa·s vinyl-terminated polysiloxane was purchased from Zhejiang Runhe Organosilicon New Materials Co., Ltd., model RH-Vi351; The 60 mPa·s hydrogen-containing polysiloxane was purchased from Zhejiang Runhe Organosilicon New Materials Co., Ltd., model RH-H512. 3-Methacryloxypropyltriethoxysilane coupling agent was purchased from Shin-Etsu Chemical Industry Co., Ltd., model KBE-503; The 3-methyl-1-dodecyn-3-ol curing inhibitor was purchased from Guangzhou Chenxi New Material Technology Co., Ltd., model CX-5002H; Aluminum hydroxide with an average particle size of 3 micrometers was purchased from Guangdong Haike New Material Technology Co., Ltd., model ATH-1. Aluminum hydroxide with an average particle size of 10 micrometers was purchased from Guangdong Haike New Material Technology Co., Ltd., model ATH-10B. Aluminum hydroxide with an average particle size of 15 micrometers was purchased from Suzhou Shizhinian New Material Technology Co., Ltd., model LA-6. Electrolytic-grade zinc oxide with an average particle size of 3 micrometers was purchased from Bam Chemical Company Ltd. Zinc borate with an average particle size of 15 micrometers was purchased from Shandong Wuwei Flame Retardant Technology Co., Ltd., model ZB80. The hydrotalcite with an average particle size of 5 micrometers was purchased from KSM Advanced Materials Technology Co., Ltd., model HT3. The fumed silica was purchased from Yichang Huifu Silicon Materials Co., Ltd., model HB-132.

[0048] Example 1: A white, low-density, flame-retardant liquid silicone rubber, the preparation steps of which are as follows: a) At 25°C, add 1 kg of vinyl-terminated polysiloxane with a viscosity of 5000 mpa.s and a vinyl content of 0.16%; 1 kg of vinyl-terminated polysiloxane with a viscosity of 20000 mpa.s and a vinyl content of 0.1%; 0.2 kg of hydrogen-containing polysiloxane with a viscosity of 60 mpa.s at 25°C and a hydrogen content of 1.24%; 0.01 kg of 3-methacryloyloxypropyltrisilane coupling agent and 0.001 kg of 3-methyl-1-dodecyn-3-ol curing inhibitor to a planetary mixer and mix for 20 minutes until the adhesive is homogeneous; b) Add 0.8 kg of aluminum hydroxide with an average particle size of 3 micrometers and 0.5 kg of aluminum hydroxide with an average particle size of 15 micrometers to the planetary mixer in sequence, and stir for 10 minutes after each addition; c) Add 0.3 kg of electrolytic zinc oxide with an average particle size of 3 micrometers, 0.3 kg of hydrotalcite with an average particle size of 5 micrometers, 0.2 kg of zinc borate with an average particle size of 15 micrometers and 0.2 kg of fumed silica with an average particle size of 20 nanometers to a planetary mixer and stir for 45 minutes. d) Add 0.01 kg of chloroplatinic acid catalyst and stir for 10 minutes; e) Vacuum stirring for 20 minutes, pressure gauge reading 0.098 MPa; f) Stop the vacuum, inject the rubber material into the mold, heat it to 120°C and vulcanize it for 10 minutes to obtain a white low-density flame-retardant silicone rubber product.

[0049] Example 2: A white, low-density, flame-retardant liquid silicone rubber, the preparation steps of which are as follows: a) At 25°C, add 1 kg of vinyl-terminated polysiloxane with a viscosity of 5000 mpa.s and a vinyl content of 0.16%; 1 kg of vinyl-terminated polysiloxane with a viscosity of 50000 mpa.s and a vinyl content of 0.25%; 0.2 kg of hydrogen-containing polysiloxane with a viscosity of 60 mpa.s at 25°C and a hydrogen content of 1.24%; 0.01 kg of 3-methacryloyloxypropyltrisilane coupling agent and 0.001 kg of 3-methyl-1-dodecyn-3-ol curing inhibitor to a planetary mixer and mix for 20 minutes until the adhesive is homogeneous; b) Add 0.8 kg of aluminum hydroxide with an average particle size of 3 micrometers and 0.5 kg of aluminum hydroxide with an average particle size of 15 micrometers to the planetary mixer in sequence, and stir for 10 minutes after each addition; c) Add 0.3 kg of electrolytic zinc oxide with an average particle size of 3 micrometers, 0.3 kg of hydrotalcite with an average particle size of 5 micrometers, 0.2 kg of zinc borate with an average particle size of 15 micrometers and 0.2 kg of fumed silica with an average particle size of 20 nanometers to a planetary mixer and stir for 45 minutes. d) Add 0.01 kg of chloroplatinic acid catalyst and stir for 10 minutes; e) Vacuum stirring for 20 minutes, pressure gauge reading 0.098 MPa; f) Stop the vacuum, inject the rubber material into the mold, heat it to 120°C and vulcanize it for 10 minutes to obtain a white low-density flame-retardant silicone rubber product.

[0050] Example 3 a) At 25°C, add 1 kg of vinyl-terminated polysiloxane with a viscosity of 5000 mpa.s and a vinyl content of 0.16%; 1 kg of vinyl-terminated polysiloxane with a viscosity of 20000 mpa.s and a vinyl content of 0.1%; 0.2 kg of hydrogen-containing polysiloxane with a viscosity of 60 mpa.s at 25°C and a hydrogen content of 1.24%; 0.01 kg of 3-methacryloyloxypropyltrisilane coupling agent and 0.001 kg of 3-methyl-1-dodecyn-3-ol curing inhibitor to a planetary mixer and mix for 20 minutes until the adhesive is homogeneous; b) Add 1.3 kg of aluminum hydroxide with an average particle size of 15 micrometers to a planetary mixer and stir for 10 minutes; c) Add 0.3 kg of electrolytic zinc oxide with an average particle size of 3 micrometers, 0.3 kg of hydrotalcite with an average particle size of 5 micrometers, 0.2 kg of zinc borate with an average particle size of 15 micrometers and 0.2 kg of fumed silica with an average particle size of 20 nanometers to a planetary mixer and stir for 45 minutes. d) Add 0.01 kg of chloroplatinic acid catalyst and stir for 10 minutes; e) Vacuum stirring for 20 minutes, pressure gauge reading 0.098 MPa; f) Stop the vacuum, inject the rubber material into the mold, heat it to 120°C and vulcanize it for 10 minutes to obtain a white low-density flame-retardant silicone rubber product.

[0051] Comparative Example 1: a) At 25°C, add 1 kg of vinyl-terminated polysiloxane with a viscosity of 5000 mpa.s and a vinyl content of 0.16%; 1 kg of vinyl-terminated polysiloxane with a viscosity of 20000 mpa.s and a vinyl content of 0.1%; 0.2 kg of hydrogen-containing polysiloxane with a viscosity of 60 mpa.s at 25°C and a hydrogen content of 1.24%; 0.01 kg of 3-methacryloyloxypropyltrisilane coupling agent and 0.001 kg of 3-methyl-1-dodecyn-3-ol curing inhibitor to a planetary mixer and mix for 20 minutes until the adhesive is homogeneous; b) Add 1.2 kg of aluminum hydroxide with an average particle size of 3 micrometers and 1.5 kg of aluminum hydroxide with an average particle size of 15 micrometers to the planetary mixer in sequence, and stir for 10 minutes after each addition; c) Add 0.01 kg of chloroplatinic acid catalyst and stir for 10 minutes; d) Vacuum stirring for 20 minutes, pressure gauge reading 0.098 MPa; e) Stop the vacuum, inject the rubber material into the mold, heat it to 120°C and vulcanize it for 10 minutes to obtain a white, low-density, flame-retardant silicone rubber product.

[0052] Comparative Example 2: a) At 25°C, add 1 kg of vinyl-terminated polysiloxane with a viscosity of 5000 mpa.s and a vinyl content of 0.16%; 1 kg of vinyl-terminated polysiloxane with a viscosity of 50000 mpa.s and a vinyl content of 0.25%; 0.2 kg of hydrogen-containing polysiloxane with a viscosity of 60 mpa.s at 25°C and a hydrogen content of 1.24%; 0.01 kg of 3-methacryloyloxypropyltrisilane coupling agent and 0.001 kg of 3-methyl-1-dodecyne-3-ol curing inhibitor to a planetary mixer and mix for 20 minutes until the adhesive is homogeneous; b) Add 1.5 kg of aluminum hydroxide with an average particle size of 3 micrometers and 1.2 kg of aluminum hydroxide with an average particle size of 15 micrometers to the planetary mixer in sequence, and stir for 10 minutes after each addition; c) Add 0.01 kg of chloroplatinic acid catalyst and stir for 10 minutes; d) Vacuum stirring for 20 minutes, pressure gauge reading 0.098 MPa; e) Stop the vacuum, inject the rubber material into the mold, heat it to 120°C and vulcanize it for 10 minutes to obtain a white, low-density, flame-retardant silicone rubber product.

[0053] Comparative Example 3 a) At 25°C, add 2 kg of vinyl-terminated polysiloxane with a viscosity of 20000 mpa.s and a vinyl content of 0.16%; 0.2 kg of hydrogen-containing polysiloxane with a viscosity of 60 mpa.s at 25°C and a hydrogen content of 1.24%; 0.01 kg of 3-methacryloyloxypropyltrisilane coupling agent; and 0.001 kg of 3-methyl-1-dodecyne-3-ol curing inhibitor to a planetary mixer and mix for 20 minutes until the adhesive is homogeneous. b) Add 2.7 kg of aluminum hydroxide with an average particle size of 3 micrometers to the planetary mixer. c) Add 0.01 kg of chloroplatinic acid catalyst and stir for 10 minutes; d) Vacuum stirring for 20 minutes, pressure gauge reading 0.098 MPa; e) Stop the vacuum, inject the rubber material into the mold, heat it to 120°C and vulcanize it for 10 minutes to obtain a white, low-density, flame-retardant silicone rubber product.

[0054] The performance of the above-mentioned white low-density flame-retardant liquid silicone rubber was tested, and the test results are shown in Table 1 below: The hardness test method refers to GB / T531.1-2008; The density test method refers to GB / T533-2008; The tensile strength test method shall refer to GB / T 528-2009; The viscosity test method for rubber compounds shall refer to GB / T 2794-2022; The flame retardancy rating test method is in accordance with UL 94-2023;

[0055] Table 1

[0056] As can be seen from Table 1, the rubber compound prepared by the present invention has good processability, high strength, lower density, and excellent flame retardant effect.

[0057] In summary, this invention effectively overcomes the various shortcomings of the prior art and has high industrial application value.

[0058] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any form or substance. It should be noted that those skilled in the art can make various improvements and additions without departing from the method of the present invention, and these improvements and additions should also be considered within the scope of protection of the present invention. Any modifications, alterations, and equivalent changes made by those skilled in the art based on the above-disclosed technical content without departing from the spirit and scope of the present invention are equivalent embodiments of the present invention. Furthermore, any modifications, alterations, and evolutions made to the above embodiments based on the essential technology of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A white, low-density, flame-retardant silicone rubber, characterized in that, The white low-density flame-retardant silicone rubber comprises the following components in parts by weight: 10 to 50 parts of a first vinyl-terminated polysiloxane; 10 to 50 parts of a second vinyl-terminated polysiloxane; 0.5 to 5 parts of hydrogen-containing polysiloxane; Acyloxysilane coupling agent, 0.01 ~ 0.1 parts; Platinum catalyst 0.05 ~ 0.5 parts; Alkyne inhibitors, 0.01 ~ 0.1 parts; 20-80 parts of inorganic flame-retardant filler; 1 to 5 parts of silica; 10-30 parts of the synergistic flame retardant system; Wherein, the first vinyl-terminated polysiloxane has a viscosity of 2000~5000 mpa.s at 25°C, and the second vinyl-terminated polysiloxane has a viscosity of 10000~100000 mpa.s at 25°C; the inorganic flame-retardant filler is selected from aluminum hydroxide, and the synergistic flame-retardant system is selected from one or more of hydrotalcite, electrolytic zinc oxide, and zinc borate.

2. The white low-density flame-retardant silicone rubber as described in claim 1, characterized in that, The vinyl content in the first vinyl-terminated polysiloxane is 0.1% to 1%.

3. The white low-density flame-retardant silicone rubber as described in claim 1, characterized in that, The vinyl content in the second vinyl-terminated polysiloxane is 0.1% to 0.6%.

4. The white low-density flame-retardant silicone rubber as described in claim 1, characterized in that, It also includes one or more of the following conditions: A1) The viscosity of the hydrogen-containing polysiloxane at 25°C is 20 ~ 500 mPa·s; A2) The hydrogen content of the hydrogen-containing polysiloxane is 0.3% to 1.6%.

5. The white low-density flame-retardant silicone rubber as described in claim 1, characterized in that, It also includes one or more of the following conditions: B1) The acyloxysilane coupling agent is selected from one or more of 3-methacryloxypropyltriethoxysilane coupling agent and isopropyl dioleoyloxytitanate coupling agent; B2) The platinum catalyst described is a chloroplatinic acid catalyst; B3) The alkynol inhibitor is selected from one or more of 3-methyl-1-dodecyn-3-ol curing inhibitor and ethynylcyclohexanol.

6. The white low-density flame-retardant silicone rubber as described in claim 1, characterized in that, The average particle size of the inorganic flame-retardant filler is 3 to 20 micrometers.

7. The white low-density flame-retardant silicone rubber as described in claim 1, characterized in that, It also includes one or more of the following conditions: C1) The silica described is fumed silica; The average particle size of the silica described in C2 is 10-20 nanometers.

8. The white low-density flame-retardant silicone rubber as described in claim 1, characterized in that, The average particle size of the synergistic flame retardant system is 2 to 20 micrometers.

9. The method for preparing white low-density flame-retardant silicone rubber according to any one of claims 1 to 8, characterized in that, The preparation method includes the following steps: 1) Mix and stir the first vinyl-terminated polysiloxane, the second vinyl-terminated polysiloxane, the hydrogen-containing polysiloxane, the acyloxysilane coupling agent, and the alkynyl alcohol inhibitor to obtain the first mixture; 2) Add inorganic flame retardant filler to the first mixture obtained in step 1) and stir to obtain a second mixture; 3) Add silica and the synergistic flame retardant system to the second mixture obtained in step 2) and stir to obtain the third mixture; 4) Add platinum catalyst to the third mixture obtained in step 3) and stir to obtain a rubber compound; 5) Vacuum the rubber and maintain it for a period of time. Then, open the air to the atmosphere, extrude the prepared rubber material, place it in a mold for vulcanization, and obtain white low-density flame-retardant silicone rubber.

10. The application of the white low-density flame-retardant silicone rubber as described in any one of claims 1 to 8 and / or the white low-density flame-retardant silicone rubber prepared by the preparation method as described in claim 9 in the field of electric vehicle enclosure sealing.

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