Weather-resistant flame-retardant sealant and preparation method thereof

Abstract

The invention relates to a weather-resistant flame-retardant sealant and a preparation method thereof, and belongs to the technical field of sealant preparation. The sealant is prepared from modified silane resin, flame-retardant powder, an epoxy catalyst, a carbon black coloring agent and a silane coupling agent according to a certain proportion. The modified silane resin is prepared by modifying bis [(3-methyldimethoxysilyl) propyl] propylene oxide and a vinylidene fluoride-hexafluoropropylene copolymer in a specific proportion under the action of a synergistic catalyst; the flame-retardant powder is prepared by dispersing expanded graphite and antimony oxide in alkaline silica sol. The preparation process of the sealant comprises the following steps: uniformly mixing the components, refining the flame-retardant powder and the carbon black coloring agent through a three-roller grinder, adding the epoxy catalyst, stirring, injecting into a mold, carrying out vacuum defoaming treatment and standing curing, and finally drying to obtain a final product. The sealant prepared by the invention has excellent weather resistance and flame retardance, is suitable for multiple fields, and provides a safe and reliable sealing solution.

Description

Technical Field

[0001] The invention belongs to the technical field of sealant preparation, and relates to a weather-resistant flame-retardant sealant and a preparation method thereof. Background Art

[0002] In the field of sealants, weather resistance and flame retardancy are two crucial performance indicators. However, traditional sealants often find it difficult to meet both requirements at the same time. On the one hand, conventional silane sealants mostly use a single resin system, which has poor weather resistance. Long-term exposure to harsh environments can easily lead to aging, cracking and other problems, affecting the sealing effect and service life. On the other hand, traditional flame-retardant sealants usually improve their flame retardant properties by adding a large amount of flame retardants, but this often leads to a decrease in the mechanical properties of the sealant, poor processing performance, and the flame retardant is prone to migration and failure, affecting the long-term use effect.

[0003] In addition, the preparation process of traditional sealants also has many limitations. For example, the compatibility of flame retardants with resin matrices is poor, and they need to rely on a large amount of solvents for dispersion, which not only increases production costs, but may also cause volatile organic compounds (VOC) to exceed the standard and fail to meet environmental protection requirements. At the same time, the homogenization and freeze-drying processing parameters in traditional processes are rough, making it difficult to effectively control the particle size and dispersion uniformity of flame retardant powder, affecting the density and flame retardant properties of the sealant.

[0004] Therefore, it is necessary to develop a new type of weather-resistant flame-retardant sealant to solve the problems existing in the prior art. This application achieves a synergistic improvement in the weather resistance, flame retardancy and processing performance of the sealant by adopting modified silane resin and a specific preparation process, as well as an optimized flame retardant powder formula and refinement process, thus meeting the market demand for high-performance sealants. Summary of the invention

[0005] The purpose of the present invention is to provide a weather-resistant flame-retardant sealant and a preparation method thereof, which has the characteristics of good flame retardancy and high weather resistance.

[0006] The purpose of the present invention can be achieved through the following technical solutions: A weather-resistant flame-retardant sealant, wherein the sealant has the following formula: by weight, 30-50 parts of modified silane resin, 15-35 parts of flame-retardant powder, 1-5 parts of epoxy catalyst, 0.5-3 parts of carbon black colorant, and 1-5 parts of silane coupling agent; The modified silane resin is prepared by mixing bis[(3-methyldimethoxysilyl)propyl]propylene oxide and vinylidene fluoride-hexafluoropropylene copolymer, and then modified by a synergistic catalyst obtained by mixing tetrabutylammonium hydroxide and tetrapropylammonium hydroxide. The flame retardant powder is prepared by dispersing expanded graphite and antimony oxide in alkaline silica sol with a purity of 40%.

[0007] Furthermore, the specific preparation method of the modified silane resin is as follows: S2.1: Tetrabutylammonium hydroxide and tetrapropylammonium hydroxide are mixed in a molar ratio of 1:(1-2), and stirred at a speed of 200 r / min for 0.5 h to obtain a mixture A; S2.2: heating bis[(3-methyldimethoxysilyl)propyl]propylene oxide to 180-220°C in a twin-screw extruder, and then adding vinylidene fluoride-hexafluoropropylene copolymer in a mass ratio of (5-10):1, and a shear rate of 100-200 times / s to obtain a mixture B; S2.3: Mix mixture A and mixture B in a mass ratio of 3:1, increase the shear rate to 220-250 times / s, and the shear time is 1-2 hours. After completion, cool to room temperature to obtain the modified silane resin.

[0008] Furthermore, the flame retardant powder preparation method is to grind the expanded graphite and antimony oxide powder to 200 mesh respectively, mix them in a mass ratio of 1:1, disperse them in an alkaline silica sol with a purity of 40%, perform ultrasonic treatment for 15 minutes, perform homogenization treatment 3 to 4 times, freeze-dry the mixture obtained by the homogenization treatment, and crush and grind it after freeze-drying to obtain the flame retardant powder.

[0009] Furthermore, the epoxy catalyst is one or more of dibutyltin dilaurate and tetra-n-butyl titanate.

[0010] Furthermore, the silane coupling agent is one or more of silane coupling agent KH550 and silane coupling agent KH560.

[0011] Furthermore, the parameters of the homogenization treatment are: pressure 40-50 MPa, temperature 30-50° C., and standing for 7 minutes after each homogenization.

[0012] Furthermore, the parameters of the freeze-drying treatment are pre-freezing at -50~-40°C for 2~4h, sublimation drying at a vacuum degree of 10~30MPa, a temperature of -20~0°C, a time of 12~24h, and finally analytical drying at a vacuum degree of 1~10MPa, a temperature of 15~20°C, a time of 4~8h, until the moisture content is ≤5%.

[0013] A method for preparing a weather-resistant flame-retardant sealant, the specific process of the preparation method of the sealant is as follows: S8.1: Add the modified silane resin into a mixer, then add the silane coupling agent and the carbon black colorant, stir at a speed of 500-800 r / min for 20-30 min to ensure uniform dispersion, then add the flame retardant powder, increase the speed to 1000-1500 r / min, stir for 40-60 min, and obtain a mixed slurry I; S8.2: Transfer the mixed slurry I to a three-roll mill, adjust the roller spacing to 10-20 μm, and grind 3-5 times in a cycle to fully refine the flame retardant powder and carbon black colorant to obtain a uniform slurry II; S8.3: Slowly add the epoxy catalyst into slurry II, continue stirring at a rate of 200-400 r / min for 10-15 minutes, inject into the mold after stirring, degas in a vacuum degassing machine, stand and cure at room temperature for 24 hours after degassing, transfer to an oven after standing and curing, gradually heat to 80-100°C, dry for 4-6 hours, cool to room temperature after drying, and obtain the sealant.

[0014] Furthermore, the flame retardant powder and carbon black colorant in S8.2 are refined to a particle size of ≤10 μm.

[0015] Furthermore, the degassing treatment parameters in S8.3 are degassing for 30 to 45 minutes at a vacuum degree of -0.095 to -0.098 MPa.

[0016] [(3-methyldimethoxysilyl)propyl]propylene oxide in the present invention was purchased from Nanjing Silicon Innovation Materials Co., Ltd. with a purity of 95%; vinylidene fluoride-hexafluoropropylene in the present invention was purchased from Shanghai Jiader Chemical Technology Co., Ltd.; tetrabutylammonium hydroxide in the present invention was purchased from Shanghai Lanrun Chemical Co., Ltd. with a purity of 99%; tetrapropylammonium hydroxide in the present invention was purchased from Shenyang Deyuan Tianhai Biotechnology Co., Ltd. with a purity of 99%; alkaline silica sol with a purity of 40% in the present invention was purchased from Jinan Feiyue Chemical Co., Ltd.; The modified silane resin in the present invention is a key component of the weather-resistant flame-retardant sealant. Its unique formula and preparation process give the sealant a series of excellent properties. The modified silane resin is prepared by mixing bis[(3-methyldimethoxysilyl)propyl]propylene oxide and vinylidene fluoride-hexafluoropropylene copolymer, and is modified under the action of a synergistic catalyst obtained by mixing tetrabutylammonium hydroxide and tetrapropylammonium hydroxide. In this preparation process, the addition of each substance carries a specific purpose, and the substances act together on the modification of the resin through a synergistic mechanism, which significantly improves the overall performance of the sealant.

[0017] As the main raw material of the resin, the epoxy group of bis[(3-methyldimethoxysilyl)propyl]propylene oxide provides good reactivity and can chemically cross-link with other components in the subsequent processing to form a dense and stable network structure. This structure not only enhances the mechanical properties of the resin, such as tensile strength and hardness, but also improves its weather resistance, allowing the sealant to maintain stable performance for a long time in harsh environments.

[0018] The addition of vinylidene fluoride-hexafluoropropylene copolymer is to further improve the weather resistance and chemical stability of the resin. The introduction of fluorine can significantly reduce the surface energy of the resin, making it more repellent to liquids such as water and oil, thereby enhancing the waterproof and oil-proof properties of the sealant. At the same time, the structure of the copolymer makes the resin more flexible, improves its impact resistance and crack resistance, and makes the sealant less likely to break when subjected to external forces.

[0019] Tetrabutylammonium hydroxide and tetrapropylammonium hydroxide play a vital role as synergistic catalysts in the modification process of resins. They promote the cross-linking reaction between resin molecules by providing an alkaline environment, making the modification more thorough and uniform. The mixed use of the two ammonium hydroxides can form a more effective catalytic system, improve the reaction rate and conversion rate, thereby shortening the preparation time and improving production efficiency. In the modification process, bis[(3-methyldimethoxysilyl)propyl]propylene oxide and vinylidene fluoride-hexafluoropropylene copolymer as raw materials need to be mixed and reacted under a certain temperature and shearing action. These reactions proceed relatively slowly at room temperature and require catalysts to accelerate the reaction rate. The mixed use of tetrabutylammonium hydroxide and tetrapropylammonium hydroxide forms a synergistic catalytic system. This system can more effectively reduce the activation energy of the reaction, so that the cross-linking reaction between resin molecules can be completed at a lower temperature and in a shorter time.

[0020] Specifically, the hydroxide ions in the synergistic catalyst can react with the active groups in the resin molecules to promote the chemical bonding between them. At the same time, the synergistic effect of the two ammonium hydroxides can also improve the activity and selectivity of the catalyst, making the reaction more thorough and uniform. Under the action of shear force, the contact between the resin molecules is closer, and the reaction rate is further accelerated. Finally, under the action of the synergistic catalyst, bis[(3-methyldimethoxysilyl)propyl]propylene oxide and vinylidene fluoride-hexafluoropropylene copolymer successfully underwent a cross-linking reaction to form a modified silane resin with excellent performance.

[0021] In the specific preparation process, tetrabutylammonium hydroxide and tetrapropylammonium hydroxide are first mixed in a molar ratio of 1: (1~2), and mixture A is obtained by stirring. This step provides a uniform alkaline environment for the subsequent catalytic reaction. Next, bis[(3-methyldimethoxysilyl)propyl]propylene oxide is heated to a suitable temperature range in a twin-screw extruder, and then vinylidene fluoride-hexafluoropropylene copolymer is added to obtain mixture B by shearing. This step achieves full mixing and preliminary modification of the two main raw materials. Finally, mixture A and mixture B are mixed in a mass ratio of 3:1, the shear rate is further increased, and a long-term shear treatment is performed. After completion, it is slowly cooled to room temperature to obtain a modified silane resin. This step promotes deep crosslinking between resin molecules through the action of a synergistic catalyst, forming a modified silane resin with excellent performance.

[0022] The present invention uses expanded graphite and antimony oxide as the main components of the flame retardant powder, each of which has a unique flame retardant mechanism. Expanded graphite can expand rapidly at high temperatures to form a dense carbonized layer, effectively isolating oxygen and heat, thereby delaying the spread of fire. Antimony oxide can release oxygen during the combustion process, react with combustibles, reduce the combustion rate, and generate stable compounds to further prevent the combustion. Mixing these two components in a mass ratio of 1:1 can give full play to their synergistic flame retardant effect and improve the overall performance of the flame retardant powder.

[0023] However, simple mixing is not enough to ensure the good performance of flame retardant powder in sealant. In order to ensure that the flame retardant powder can be evenly dispersed in the matrix material and remain stable during use, the present invention selects alkaline silica sol with a purity of 40% as a dispersion medium. Silica sol has excellent dispersibility and stability, and can evenly wrap expanded graphite and antimony oxide powder therein to form a stable suspension. This suspension is not prone to precipitation and agglomeration during subsequent processing, ensuring the uniform dispersion of the flame retardant powder. During the preparation process, ultrasonic treatment can further break the agglomeration structure of expanded graphite and antimony oxide powder, so that they are more evenly dispersed in the silica sol. The subsequent 3 to 4 homogenization treatments use the effects of high pressure and shear force to further refine the flame retardant powder particles and increase their specific surface area and reactivity. The flame retardant powder treated in this way is not only more evenly dispersed, but also has a larger contact area with the matrix material and stronger interaction, which is conducive to the performance of flame retardant properties. Finally, the water in the mixture obtained by homogenization is removed by freeze drying to obtain a loose and porous flame retardant powder. This structure is conducive to the rapid release of flame retardant ingredients in the flame retardant powder during combustion, and exerting a flame retardant effect. At the same time, the freeze-drying process also maintains the original morphology and dispersion state of the flame retardant powder, avoiding agglomeration and agglomeration during the drying process.

[0024] In the preparation process of the sealant of the present invention, the modified silane resin, the silane coupling agent and the carbon black colorant are firstly fully mixed by a stirrer to ensure that each component is evenly dispersed. Subsequently, the flame retardant powder is added, and the stirring speed is increased so that the flame retardant powder and other components are fully integrated to form a mixed slurry I. This step effectively improves the dispersibility and uniformity of the flame retardant powder in the sealant, laying a solid foundation for the flame retardant performance of the sealant. Then the mixed slurry I is transferred to a three-roll grinder for cyclic grinding, and the flame retardant powder and the carbon black colorant are fully refined by adjusting the roller spacing to the micron level to obtain a uniform slurry II. This step further improves the fineness and uniformity of the sealant and ensures the good performance of the sealant during use. Finally, the epoxy catalyst is slowly added to the slurry II, and after continued stirring, it is injected into the mold, and vacuum degassing treatment and static curing are performed. By gradually heating and drying, the sealant is completely cured to obtain the final product. This step not only ensures the curing effect of the sealant, but also effectively removes bubbles in the sealant through vacuum degassing treatment, thereby improving the compactness and weather resistance of the sealant.

[0025] Beneficial effects of the present invention: The modified silane resin in the present invention is used as a key component of the sealant. It is prepared by mixing bis[(3-methyldimethoxysilyl)propyl]propylene oxide and vinylidene fluoride-hexafluoropropylene copolymer and under the synergistic catalytic action of tetrabutylammonium hydroxide and tetrapropylammonium hydroxide, which significantly enhances the weather resistance of the resin, so that the sealant can maintain stable performance for a long time in harsh environments. The present invention uses expanded graphite and antimony oxide as the main components of the flame retardant powder, and ensures the uniform dispersion and stable existence of the flame retardant powder in the sealant through mixing in a specific ratio and using a silica sol dispersion medium. The addition of the flame retardant powder effectively improves the flame retardant performance of the sealant, can quickly form a carbonized layer during the combustion process, isolate oxygen and heat, reduce the combustion speed, and further prevent the combustion from proceeding. DETAILED DESCRIPTION

[0026] In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the specific implementation methods, structures, features and effects of the present invention are described in detail below in combination with the embodiments.

[0027] Example 1

[0028] A weather-resistant flame-retardant sealant, the sealant formula is as follows, by weight, 40 parts of modified silane resin, 25 parts of flame-retardant powder, 3 parts of dibutyltin dilaurate, 1 part of carbon black colorant, and 3 parts of silane coupling agent KH550; The specific preparation method of the modified silane resin is as follows: S2.1: Tetrabutylammonium hydroxide and tetrapropylammonium hydroxide were mixed in a molar ratio of 1:1, and stirred at a speed of 200 r / min for 0.5 h to obtain a mixture A; S2.2: heating bis[(3-methyldimethoxysilyl)propyl]propylene oxide to 200° C. in a twin-screw extruder, and then adding vinylidene fluoride-hexafluoropropylene copolymer in a mass ratio of 7:1, and a shear rate of 200 times / s to obtain a mixture B; S2.3: Mix mixture A and mixture B in a mass ratio of 3:1, increase the shear rate to 250 times / s, and the shear time is 1.5 hours. After completion, cool to room temperature to obtain the modified silane resin.

[0029] The flame retardant powder preparation method comprises the following steps: grinding expanded graphite and antimony oxide powder to 200 meshes respectively, mixing them in a mass ratio of 1:1, dispersing them in an alkaline silica sol with a purity of 40%, subjecting them to ultrasonic treatment for 15 minutes, and then subjecting them to homogenization treatment for 4 times. The parameters of the homogenization treatment are pressure of 50 MPa and temperature of 30°C. After each homogenization, the mixture is allowed to stand for 7 minutes. The mixture obtained by the homogenization treatment is freeze-dried. The parameters of the freeze-drying treatment are pre-freezing at -50°C for 2 hours, sublimation drying at a vacuum degree of 30 MPa, temperature of 0°C, and time of 18 hours. Finally, analytical drying at a vacuum degree of 5 MPa, temperature of 20°C, and time of 6 hours until the moisture content is ≤5%. After freeze-drying, the mixture is crushed and ground to obtain the flame retardant powder.

[0030] The specific process of the preparation method of the sealant is as follows: S8.1: Add the modified silane resin into a mixer, then add the silane coupling agent and the carbon black colorant, stir at a speed of 800 r / min for 20 min to ensure uniform dispersion, then add the flame retardant powder, increase the speed to 1500 r / min, stir for 40 min, and obtain a mixed slurry I; S8.2: Transfer the mixed slurry I to a three-roll mill, adjust the roller spacing to 15 μm, and grind it 4 times in a cycle to fully refine the flame retardant powder and carbon black colorant to a particle size of ≤10 μm to obtain a uniform slurry II; S8.3: Slowly add the epoxy catalyst into slurry II, continue stirring at a rate of 400 r / min for 10 minutes, inject into the mold after stirring, and perform degassing treatment in a vacuum degassing machine. The degassing treatment parameters are degassing at a vacuum degree of -0.098MPa for 40 minutes. After degassing, stand and cure at room temperature for 24 hours. After standing and curing, transfer to an oven, gradually heat up to 100°C, dry for 4 hours, and cool to room temperature after drying to obtain the sealant.

[0031] Example 2

[0032] A weather-resistant flame-retardant sealant, the sealant formula is as follows, by weight, 30 parts of modified silane resin, 15 parts of flame-retardant powder, 1 part of tetra-n-butyl titanate, 0.5 parts of carbon black colorant, and 1 part of silane coupling agent KH560; The specific preparation method of the modified silane resin is as follows: S2.1: Tetrabutylammonium hydroxide and tetrapropylammonium hydroxide were mixed in a molar ratio of 1:1, and stirred at a speed of 200 r / min for 0.5 h to obtain a mixture A; S2.2: heating bis[(3-methyldimethoxysilyl)propyl]propylene oxide to 180° C. in a twin-screw extruder, and then adding vinylidene fluoride-hexafluoropropylene copolymer in a mass ratio of 5:1, and a shear rate of 100 times / s to obtain a mixture B; S2.3: Mix mixture A and mixture B in a mass ratio of 3:1, increase the shear rate to 220 times / s, and the shear time is 1 hour. After completion, cool to room temperature to obtain the modified silane resin.

[0033] The flame retardant powder preparation method comprises the following steps: grinding expanded graphite and antimony oxide powder to 200 meshes respectively, mixing them in a mass ratio of 1:1, dispersing them in an alkaline silica sol with a purity of 40%, subjecting them to ultrasonic treatment for 15 minutes, subjecting them to homogenization treatment for 3 times, wherein the parameters of the homogenization treatment are pressure of 40 MPa and temperature of 30°C, standing for 7 minutes after each homogenization, subjecting the mixture obtained by the homogenization treatment to freeze-drying treatment, wherein the parameters of the freeze-drying treatment are pre-freezing at -50°C for 2 hours, sublimation drying at a vacuum degree of 10 MPa, temperature of -20°C, and time of 12 hours, and finally analytical drying at a vacuum degree of 1 MPa, temperature of 15°C, and time of 4 hours until the moisture content is ≤5%, crushing and grinding after freeze-drying, and obtaining the flame retardant powder.

[0034] The specific process of the preparation method of the sealant is as follows: S8.1: Add the modified silane resin into a mixer, then add the silane coupling agent and the carbon black colorant, stir at a speed of 500 r / min for 20 min to ensure uniform dispersion, then add the flame retardant powder, increase the speed to 1000 r / min, stir for 40 min, and obtain a mixed slurry I; S8.2: Transfer the mixed slurry I to a three-roll mill, adjust the roller spacing to 10 μm, and grind it three times in a cycle to fully refine the flame retardant powder and carbon black colorant to a particle size of ≤10 μm to obtain a uniform slurry II; S8.3: Slowly add the epoxy catalyst into slurry II, continue stirring at a rate of 200 r / min for 10 minutes, inject into the mold after stirring, and perform degassing treatment in a vacuum degassing machine. The degassing treatment parameters are degassing for 30 minutes at a vacuum degree of -0.095MPa. After degassing, let it stand and cure at room temperature for 24 hours. After standing and curing, transfer it to an oven, gradually heat it to 80°C, dry it for 4 hours, and cool it to room temperature after drying to obtain the sealant.

[0035] Example 3

[0036] A weather-resistant flame-retardant sealant, wherein the sealant has the following formula: by weight, 50 parts of modified silane resin, 35 parts of flame-retardant powder, 5 parts of dibutyltin dilaurate, 3 parts of carbon black colorant, and 5 parts of silane coupling agent KH550; The specific preparation method of the modified silane resin is as follows: S2.1: Tetrabutylammonium hydroxide and tetrapropylammonium hydroxide were mixed in a molar ratio of 1:2, and stirred at a speed of 200 r / min for 0.5 h to obtain a mixture A; S2.2: heating bis[(3-methyldimethoxysilyl)propyl]propylene oxide to 220° C. in a twin-screw extruder, and then adding vinylidene fluoride-hexafluoropropylene copolymer in a mass ratio of 10:1, and a shear rate of 200 times / s to obtain a mixture B; S2.3: Mix mixture A and mixture B in a mass ratio of 3:1, increase the shear rate to 250 times / s, and the shear time is 2 hours. After completion, cool to room temperature to obtain the modified silane resin.

[0037] The flame retardant powder preparation method comprises the following steps: grinding expanded graphite and antimony oxide powder to 200 meshes respectively, mixing them in a mass ratio of 1:1, dispersing them in an alkaline silica sol with a purity of 40%, subjecting them to ultrasonic treatment for 15 minutes, and then subjecting them to homogenization treatment for 4 times. The parameters of the homogenization treatment are pressure of 50 MPa and temperature of 50°C. After each homogenization, the mixture is allowed to stand for 7 minutes. The mixture obtained by the homogenization treatment is freeze-dried. The parameters of the freeze-drying treatment are pre-freezing at -40°C for 4 hours, sublimation drying at a vacuum degree of 30 MPa, a temperature of 0°C, and a duration of 24 hours. Finally, analytical drying is performed at a vacuum degree of 10 MPa, a temperature of 20°C, and a duration of 8 hours until the moisture content is ≤5%. After freeze-drying, the mixture is crushed and ground to obtain the flame retardant powder.

[0038] The specific process of the preparation method of the sealant is as follows: S8.1: Add the modified silane resin into a mixer, then add the silane coupling agent and the carbon black colorant, stir at a speed of 800 r / min for 30 min to ensure uniform dispersion, then add the flame retardant powder, increase the speed to 1500 r / min, stir for 60 min, and obtain a mixed slurry I; S8.2: Transfer the mixed slurry I to a three-roll mill, adjust the roller spacing to 20 μm, and grind it 5 times in a cycle to fully refine the flame retardant powder and carbon black colorant to a particle size of ≤10 μm to obtain a uniform slurry II; S8.3: Slowly add the epoxy catalyst into slurry II, continue stirring at a rate of 400 r / min for 15 minutes, inject into the mold after stirring, and perform degassing treatment in a vacuum degassing machine. The degassing treatment parameters are degassing at a vacuum degree of -0.098MPa for 45 minutes. After degassing, stand and cure at room temperature for 24 hours. After standing and curing, transfer to an oven, gradually heat up to 100°C, dry for 6 hours, and cool to room temperature after drying to obtain the sealant.

[0039] Comparative Example 1 In this comparative example, only tetrabutylammonium hydroxide is used in the preparation of the modified silane resin, and the remaining steps are consistent with those of Example 1.

[0040] Comparative Example 2 In this comparative example, only tetrapropylammonium hydroxide is used in the preparation of the modified silane resin, and the remaining steps are consistent with those of Example 1.

[0041] Comparative Example 3 In this comparative example, no expanded graphite is added in the preparation of the flame retardant powder, and the remaining steps are consistent with those of Example 1.

[0042] Comparative Example 4 In this comparative example, antimony oxide is not added in the preparation of the flame retardant powder, and the remaining steps are consistent with those of Example 1.

[0043] Comparative Example 5 In this comparative example, alkaline silica sol with a purity of 40% was not added in the preparation of the flame retardant powder, expanded graphite and antimony oxide powder were dispersed in deionized water, and the remaining steps were consistent with Example 1.

[0044] The flame retardancy and weather resistance of the embodiments and comparative examples were tested. The flame retardancy was tested in a vertical combustion test according to the flame retardancy standard GB / T 2408-2021. The weather resistance was tested in a UV aging test according to the weather resistance standard GB / T 3511-2018. The test lasted for 1000 hours. The color change (ΔE) was quantified by a colorimeter. The experimental results are summarized in Table 1. Table 1: Performance test data of sealant Burning test (grade) UV aging test (ΔE) Example 1 V0 1.5 Example 2 V0 1.5 Example 3 V0 1.5 Comparative Example 1 V1 2.0 Comparative Example 2 V1 2.0 Comparative Example 3 V2 1.8 Comparative Example 4 V2 1.8 Comparative Example 5 V2 1.8 It can be seen from the experimental data that the preparation of the modified silane resin in the present invention effectively improves the weather resistance of the prepared sealant, and the preparation of the flame retardant powder improves the flame retardant performance of the prepared sealant.

[0045] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technical personnel in this field can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A weather-resistant flame-retardant sealant, characterized in that: The sealant formula is as follows: by weight, 30-50 parts of modified silane resin, 15-35 parts of flame retardant powder, 1-5 parts of epoxy catalyst, 0.5-3 parts of carbon black colorant, and 1-5 parts of silane coupling agent; The modified silane resin is prepared by mixing bis[(3-methyldimethoxysilyl)propyl]propylene oxide and vinylidene fluoride-hexafluoropropylene copolymer, and then modified by a synergistic catalyst obtained by mixing tetrabutylammonium hydroxide and tetrapropylammonium hydroxide. The flame retardant powder is prepared by dispersing expanded graphite and antimony oxide in alkaline silica sol with a purity of 40%.

2. A weather-resistant flame-retardant sealant according to claim 1, characterized in that: The specific preparation method of the modified silane resin is as follows: S2.1: Tetrabutylammonium hydroxide and tetrapropylammonium hydroxide are mixed in a molar ratio of 1:(1-2), and stirred at a speed of 200 r / min for 0.5 h to obtain a mixture A; S2.2: heating bis[(3-methyldimethoxysilyl)propyl]propylene oxide to 180-220°C in a twin-screw extruder, and then adding vinylidene fluoride-hexafluoropropylene copolymer in a mass ratio of (5-10):1, and a shear rate of 100-200 times / s to obtain a mixture B; S2.3: Mix mixture A and mixture B in a mass ratio of 3:1, increase the shear rate to 220-250 times / s, and the shear time is 1-2 hours. After completion, cool to room temperature to obtain the modified silane resin.

3. The weather-resistant flame-retardant sealant according to claim 1, characterized in that: The flame retardant powder preparation method comprises the following steps: grinding expanded graphite and antimony oxide powder to 200 meshes respectively, mixing them in a mass ratio of 1:1, dispersing them in an alkaline silica sol with a purity of 40%, ultrasonicating for 15 minutes, homogenizing them 3 to 4 times, freeze-drying the mixture obtained by the homogenization, crushing and grinding them after freeze-drying, and obtaining the flame retardant powder.

4. The weather-resistant flame-retardant sealant according to claim 1, characterized in that: The epoxy catalyst is one or more of dibutyltin dilaurate and tetra-n-butyl titanate.

5. The weather-resistant flame-retardant sealant according to claim 1, characterized in that: The silane coupling agent is one or more of silane coupling agent KH550 and silane coupling agent KH560.

6. The weather-resistant flame-retardant sealant according to claim 3, characterized in that: The parameters of the homogenization treatment are: pressure 40-50 MPa, temperature 30-50° C., and standing for 7 minutes after each homogenization.

7. The weather-resistant flame-retardant sealant according to claim 3, characterized in that: The freeze-drying process parameters are pre-freezing at -50~-40°C for 2~4h, sublimation drying at a vacuum degree of 10~30MPa, a temperature of -20~0°C, a time of 12~24h, and finally analytical drying at a vacuum degree of 1~10MPa, a temperature of 15~20°C, a time of 4~8h, until the moisture content is ≤5%.

8. A method for preparing a weather-resistant flame-retardant sealant, based on the weather-resistant flame-retardant sealant according to any one of claims 1 to 7, characterized in that: The specific process of the preparation method of the sealant is as follows: S8.1: Add the modified silane resin into a mixer, then add the silane coupling agent and the carbon black colorant, stir at a speed of 500-800 r / min for 20-30 min to ensure uniform dispersion, then add the flame retardant powder, increase the speed to 1000-1500 r / min, stir for 40-60 min, and obtain a mixed slurry I; S8.2: Transfer the mixed slurry I to a three-roll mill, adjust the roller spacing to 10-20 μm, and grind 3-5 times in a cycle to fully refine the flame retardant powder and carbon black colorant to obtain a uniform slurry II; S8.3: Slowly add the epoxy catalyst into slurry II, continue stirring at a rate of 200-400 r / min for 10-15 minutes, inject into the mold after stirring, degas in a vacuum degassing machine, stand and cure at room temperature for 24 hours after degassing, transfer to an oven after standing and curing, gradually heat to 80-100°C, dry for 4-6 hours, cool to room temperature after drying, and obtain the sealant.

9. The method for preparing a weather-resistant flame-retardant sealant according to claim 8, characterized in that: The flame retardant powder and carbon black colorant in S8.2 are refined to a particle size of ≤10 μm.

10. The method for preparing a weather-resistant flame-retardant sealant according to claim 8, characterized in that: The parameters of the degassing treatment in S8.3 are degassing for 30 to 45 minutes at a vacuum degree of -0.095 to -0.098 MPa.