Preparation of a vermiculite-based flame-retardant and smoke-suppressing filler and its application in silicone foam
By coating the surface of expanded vermiculite with zinc hydroxystannate nanoparticles, EVMT@ZHS flame retardant and smoke suppressant filler was prepared, which solved the problem of high fire risk of silicone foam during combustion, and achieved efficient flame retardant and smoke suppressant effects, and the process is environmentally friendly.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- FUZHOU UNIV
- Filing Date
- 2026-04-07
- Publication Date
- 2026-05-26
Smart Images
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of flame retardant and flame retardant material preparation technology, specifically relating to a vermiculite-based flame retardant and smoke-suppressing filler, its preparation method, and its application in silicone foam. Background Technology
[0002] Silicone foam (SiF) is a lightweight, porous, elastic material formed through chemical or physical foaming using organosilicon polymers (polysiloxanes) as the matrix. It combines the advantages of both organosilicon and foam materials. As a novel high-performance foam material, it is widely used in building fire protection, military industry, and aerospace. Although the non-flammable inorganic siloxane backbone endows silicone foam with certain flame-retardant properties, the flammable organic side chains decompose during combustion, generating flammable gases, intensifying the combustion reaction, and releasing large amounts of toxic fumes, posing a significant fire risk. Therefore, relying solely on the non-flammability of the inorganic siloxane backbone is insufficient to meet the flame-retardant performance requirements of silicone foam in all applications. Improving the smoke-suppressing and flame-retardant properties of silicone foam and reducing its fire hazard has become a critical scientific issue that urgently needs to be addressed.
[0003] Zinc hydroxystannate (ZHS) is an inorganic tin-zinc composite flame retardant with multiple flame-retardant mechanisms: First, ZHS undergoes an endothermic dehydration reaction at approximately 200°C, losing its water of crystallization. This process absorbs a large amount of heat and dilutes the concentration of combustible gases. Second, the tin and zinc oxides generated after dehydration catalyze the cross-linking of the polymer matrix into char, forming a dense char layer barrier that effectively blocks the transfer of heat and oxygen. However, due to its high preparation cost, poor dispersibility, and poor compatibility with polymer materials, ZHS is difficult to widely apply in the field of flame-retardant polymer materials.
[0004] Expanded vermiculite (EVMT) is a layered silicate mineral characterized by low cost, light weight, and high temperature resistance. Its layered structure forms a physical barrier during combustion, blocking heat and oxygen transfer, and also improving the thermal stability and density of the char layer.
[0005] This invention utilizes an in-situ precipitation method to coat ZHS nanoparticles onto the surface of EVMT, preparing a novel flame-retardant and smoke-suppressing filler, EVMT@ZHS, achieving a synergistic effect between the two. On one hand, the layered structure of EVMT provides an effective supporting matrix for ZHS, preventing the aggregation of ZHS nanoparticles and improving their dispersibility in silicone foam; on the other hand, the catalytic char formation effect of ZHS combined with the physical barrier effect of EVMT significantly enhances both flame-retardant and smoke-suppressing efficiency. Summary of the Invention
[0006] The purpose of this invention is to provide a method for preparing vermiculite-based flame-retardant and smoke-suppressing filler and its application in silicone foam. The filler is synthesized in an aqueous phase, and the preparation process is simple and environmentally friendly. It has good compatibility with silicone foam and can effectively improve its flame-retardant and smoke-suppressing properties, and has broad application prospects in flame-retardant and smoke-suppressing silicone foam.
[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for preparing a vermiculite-based flame-retardant and smoke-suppressing filler includes the following steps: The multifunctional filler zinc hydroxystannate-encapsulated expanded vermiculite comprises the following raw materials in parts by weight: 20 parts expanded vermiculite, 4.66 parts sodium stannate trihydrate, and 5.02 parts zinc sulfate heptahydrate; The zinc hydroxystannate-coated expanded vermiculite is prepared by the following steps: (1) Weigh an appropriate amount of expanded vermiculite powder and disperse it in a certain amount of deionized water, and then make it evenly dispersed by mechanical stirring; (2) Weigh an appropriate amount of zinc sulfate and dissolve it in an appropriate amount of deionized water. Dissolve the solution by magnetic stirring to obtain a zinc sulfate solution. (3) Weigh an appropriate amount of sodium stannate and dissolve it in an appropriate amount of deionized water. Dissolve it by magnetic stirring to obtain a sodium stannate solution. (4) Add the zinc sulfate solution from step (2) to the mixed solution from step (1) and stir for a certain period of time to mix evenly; (5) Slowly add the sodium stannate solution from step (3) to the mixed solution in step (4), and adjust the pH of the solution with ammonia. Then stir the reaction at room temperature for a certain period of time. After the reaction is completed, filter the solution and wash it with deionized water. Then dry it under vacuum, pulverize it, and sieve it to obtain a brown powder product, namely zinc hydroxystannate-encapsulated expanded vermiculite EVMT@ZHS.
[0008] Further, in step (1), the amount of expanded vermiculite powder particles used is 20 parts, and the amount of deionized water used is 100 parts.
[0009] Furthermore, the zinc sulfate mentioned in step (2) is zinc sulfate heptahydrate, with a dosage of 5.02 parts and a dosage of 50 parts of deionized water.
[0010] Furthermore, the sodium stannate mentioned in step (3) is sodium stannate trihydrate, with a dosage of 4.66 parts and a dosage of 100 parts of deionized water.
[0011] Furthermore, the stirring time in step (4) is 30 min and the stirring speed is 600 rpm.
[0012] Further, in step (5), the pH value is 9-10, the stirring reaction time is 4 h, the stirring rate is 600 rpm, the vacuum drying temperature is 60 ℃, and the drying time is 12 h.
[0013] The prepared vermiculite-based flame-retardant and smoke-suppressing filler was applied to silicone foam, including the following steps: 80 parts of vinyl silicone oil, 80 parts of hydroxyl silicone oil, 10 parts of water, and 2 parts of platinum catalyst were mixed and stirred evenly to obtain component A; 80 parts of vinyl silicone oil, 80 parts of hydroxyl silicone oil, 50 parts of hydrogen-containing silicone oil, 19 parts of zinc hydroxystannate-coated expanded vermiculite, and 2 parts of V4 inhibitor were mixed and stirred evenly to obtain component B; then component A and component B were mixed and stirred thoroughly for 60 s, poured into a specific mold, foamed at room temperature for 15 min, and then placed in an 80 ℃ forced-air drying oven for 2 h to cure, thus obtaining silicone foam containing 5% vermiculite-based flame-retardant and smoke-suppressing filler.
[0014] Compared with the prior art, the present invention has the following advantages and beneficial effects: This invention first prepares a vermiculite-based flame-retardant and smoke-suppressing filler, zinc hydroxystannate, which encapsulates expanded vermiculite. This filler is then introduced into the raw materials for preparing silicone foam. The synthesis of this filler is completed in an aqueous phase, the preparation process is simple and environmentally friendly, and it exhibits good compatibility with silicone foam. The resulting silicone foam possesses highly efficient flame-retardant and smoke-suppressing properties, showing broad application prospects in flame-retardant and smoke-suppressing silicone foams. Attached Figure Description
[0015] Figure 1 FT-IR images of vermiculite-based flame retardant and smoke suppressant filler EVMT@ZHS prepared in Example 1, zinc hydroxystannate ZHS prepared in Comparative Example 1, and expanded vermiculite EVMT; Figure 2 The heat release rate curve of flame-retardant and smoke-suppressing silicone foam material during combustion; Figure 3 The total heat release curve during the combustion process of flame-retardant and smoke-suppressing silicone foam material; Figure 4 The total smoke release curve during the combustion process of flame-retardant and smoke-suppressing silicone foam material. Detailed Implementation
[0016] The technical solutions of the present invention are described below with reference to specific embodiments. The described embodiments are merely some embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the protection scope of the present invention.
[0017] Example 1: 100 mL of deionized water and 20 g of expanded vermiculite were added to a three-necked flask and stirred for 15 min to ensure uniform dispersion. Then, 5.02 g of zinc sulfate heptahydrate was weighed and dissolved in 50 mL of deionized water to prepare a zinc sulfate solution. This solution was poured into the three-necked flask, and stirring continued for 30 min to allow zinc ions to adsorb onto the surface of the expanded vermiculite. Next, 4.66 g of sodium stannate trihydrate was weighed and dissolved in 100 mL of deionized water to prepare a sodium stannate solution, which was then slowly added dropwise to the three-necked flask. The pH of the solution was adjusted to 9-10 with ammonia, and the reaction was stirred at room temperature for 4 h. After the reaction was complete, the solution was filtered, washed with deionized water, and then vacuum dried at 60 °C for 12 h to obtain zinc hydroxystannate-coated expanded vermiculite EVMT@ZHS.
[0018] Comparative Example 1: Weigh 5.02 g of zinc sulfate heptahydrate, dissolve it in 50 mL of deionized water to prepare a zinc sulfate solution, and pour it into a three-necked flask. Then weigh 4.66 g of sodium stannate trihydrate, dissolve it in 100 mL of deionized water to prepare a sodium stannate solution, and then slowly add it dropwise to the three-necked flask. Adjust the pH of the solution to 9-10 with ammonia, and then stir the reaction at room temperature for 4 h. After the reaction is complete, filter the solution, wash with deionized water, and then dry under vacuum at 60 °C for 12 h to obtain zinc hydroxystannate (ZHS).
[0019] Application Example 1: A SiF / 1EVMT@ZHS silicone foam material was synthesized according to the following steps: By weight, take 80 parts of vinyl silicone oil, 80 parts of hydroxyl silicone oil, 10 parts of water, and 2 parts of platinum catalyst, and mix them evenly to obtain component A. Take 80 parts of vinyl silicone oil, 80 parts of hydroxyl silicone oil, 50 parts of hydrogen-containing silicone oil, 3.8 parts of zinc hydroxystannate-coated expanded vermiculite, and 2 parts of V4 inhibitor, and mix them evenly to obtain component B. Mix component A and component B, stir thoroughly, pour into a specific mold, foam at room temperature for 15 min, and then place in an 80 ℃ forced-air drying oven to cure for 2 h to obtain silicone foam material (SiF / 1EVMT@ZHS).
[0020] Application Example 2; A SiF / 3EVMT@ZHS silicone foam material was synthesized according to the following steps: By weight, take 80 parts of vinyl silicone oil, 80 parts of hydroxyl silicone oil, 10 parts of water, and 2 parts of platinum catalyst, and mix them evenly to obtain component A. Take 80 parts of vinyl silicone oil, 80 parts of hydroxyl silicone oil, 50 parts of hydrogen-containing silicone oil, 11.4 parts of zinc hydroxystannate-coated expanded vermiculite, and 2 parts of V4 inhibitor, and mix them evenly to obtain component B. Mix component A and component B, stir thoroughly, pour into a specific mold, foam at room temperature for 15 min, and then place in an 80 ℃ forced-air drying oven to cure for 2 h to obtain silicone foam material (SiF / 3EVMT@ZHS).
[0021] Application Example 3; A SiF / 5EVMT@ZHS silicone foam material was synthesized according to the following steps: By weight, take 80 parts of vinyl silicone oil, 80 parts of hydroxyl silicone oil, 10 parts of water, and 2 parts of platinum catalyst, and mix them evenly to obtain component A. Take 80 parts of vinyl silicone oil, 80 parts of hydroxyl silicone oil, 50 parts of hydrogen-containing silicone oil, 19 parts of zinc hydroxystannate-coated expanded vermiculite, and 2 parts of V4 inhibitor, and mix them evenly to obtain component B. Mix component A and component B, stir thoroughly, pour into a specific mold, foam at room temperature for 15 min, and then place in an 80 ℃ forced-air drying oven to cure for 2 h to obtain silicone foam material (SiF / 5EVMT@ZHS).
[0022] Comparative Application Example 1; A Pure SiF silicone foam material was synthesized according to the following steps: By weight, take 80 parts of vinyl silicone oil, 80 parts of hydroxyl silicone oil, 10 parts of water, and 2 parts of platinum catalyst, and mix them evenly to obtain component A. Take 80 parts of vinyl silicone oil, 80 parts of hydroxyl silicone oil, 50 parts of hydrogen-containing silicone oil, and 2 parts of V4 inhibitor, and mix them evenly to obtain component B. Mix component A and component B, stir thoroughly, pour into a specific mold, foam at room temperature for 15 minutes, and then place in an 80 ℃ forced-air drying oven to cure for 2 hours to obtain silicone foam material (Pure SiF).
[0023] Comparative Application Example 2; A SiF / 5EVMT silicone foam material was synthesized according to the following steps: By weight, take 80 parts of vinyl silicone oil, 80 parts of hydroxyl silicone oil, 10 parts of water, and 2 parts of platinum catalyst, and mix them evenly to obtain component A. Take 80 parts of vinyl silicone oil, 80 parts of hydroxyl silicone oil, 50 parts of hydrogen-containing silicone oil, 19 parts of expanded vermiculite, and 2 parts of V4 inhibitor, and mix them evenly to obtain component B. Mix component A and component B, stir thoroughly, pour into a specific mold, foam at room temperature for 15 min, and then place in an 80 ℃ forced-air drying oven to cure for 2 h to obtain silicone foam material (SiF / 5EVMT).
[0024] Comparative Application Example 3: A SiF / 5ZHS silicone foam material was synthesized according to the following steps: By weight, take 80 parts of vinyl silicone oil, 80 parts of hydroxyl silicone oil, 10 parts of water, and 2 parts of platinum catalyst, and mix them evenly to obtain component A. Take 80 parts of vinyl silicone oil, 80 parts of hydroxyl silicone oil, 50 parts of hydrogen-containing silicone oil, 19 parts of zinc hydroxystannate, and 2 parts of V4 inhibitor, and mix them evenly to obtain component B. Mix component A and component B, stir thoroughly, pour into a specific mold, foam at room temperature for 15 min, and then place in an 80 ℃ forced-air drying oven to cure for 2 h to obtain silicone foam material (SiF / 5ZHS).
[0025] Figure 1 Infrared spectra of the vermiculite-based flame retardant and smoke-suppressing filler EVMT@ZHS prepared in Example 1, zinc hydroxystannate ZHS prepared in Comparative Example 1, and expanded vermiculite EVMT. In the infrared spectrum of EVMT, 457 cm⁻¹... -1 The infrared characteristic peak at 1000 cm⁻¹ corresponds to the bending vibration of Si-O-Mg. -1 The infrared characteristic peak corresponds to the tensile vibration of Si-O-Si. 1635 cm⁻¹ -1 The characteristic infrared peak at 780 cm⁻¹ corresponds to the OH deformation vibration of water molecules in the interlayer of expanded vermiculite. In the ZHS infrared spectrum, the peak at 780 cm⁻¹ corresponds to this peak. -1 The infrared characteristic peak at 1175 cm⁻¹ corresponds to the tensile vibration of Sn-O. -1 The infrared characteristic peak at 1635 cm⁻¹ corresponds to the stretching vibration of Sn-OH. -1 and 3238 cm -1 The infrared characteristic peak at the specified location corresponds to the tensile vibration of -OH. Comparison revealed that the infrared spectrum of EVMT@ZHS showed typical infrared characteristic peaks corresponding to EVMT and ZHS, confirming the successful preparation of zinc hydroxystannate-encapsulated expanded vermiculite filler.
[0026] The silicone foam materials obtained in Examples 1, 2, and 3, as well as the comparative examples 1, 2, and 3, were analyzed using a cone calorimeter. Analytical equipment: cone calorimeter; thermal radiation value: 35 kW / m² 2 The test results are shown below. Figure 2 , 3 4.
[0027] pass Figure 2 and Figure 3Calculations show that, compared to the Pure SiF silicone foam sample without zinc hydroxystannate-coated expanded vermiculite, the peak heat release rates of the silicone foam samples SiF / 1EVMT@ZHS, SiF / 3EVMT@ZHS, and SiF / 5EVMT@ZHS with added zinc hydroxystannate-coated expanded vermiculite decreased by 7.6%, 6.0%, and 31.2%, respectively. The total heat release decreased by 1.1%, 1.2%, and 40.4%, respectively. When the amount of zinc hydroxystannate-coated expanded vermiculite added was 5 wt%, the silicone foam material exhibited the best flame retardant effect, superior to silicone foam samples with only 5 wt% expanded vermiculite or 5 wt% zinc hydroxystannate added. The above analysis indicates that adding EVMT or ZHS alone has limited effect on improving the flame retardant performance of silicone foam, and that EVMT and ZHS have a good synergistic flame retardant effect.
[0028] pass Figure 4 Calculations show that, compared to the PureSiF silicone foam sample without zinc stannate-coated expanded vermiculite, the total smoke release of the silicone foam samples SiF / 1EVMT@ZHS, SiF / 3EVMT@ZHS, and SiF / 5EVMT@ZHS with a certain amount of zinc stannate-coated expanded vermiculite decreased by 65.6%, 55.3%, and 23.7%, respectively. The introduction of EVMT@ZHS can effectively suppress the release of smoke during the combustion of silicone foam.
[0029] The present invention provides a vermiculite-based flame-retardant and smoke-suppressing filler, its preparation method, and its application in silicone foam. Specific embodiments are described to illustrate the preparation process, facilitating understanding of the method and core concepts of the invention. It should be noted that those skilled in the art can make various modifications and improvements to the invention, and these modifications and improvements should also fall within the scope of protection of the claims.
Claims
1. A method for preparing a vermiculite-based flame-retardant and smoke-suppressing filler, characterized in that: Includes the following steps: (1) Disperse the expanded vermiculite powder in deionized water; (2) Add zinc sulfate to deionized water and stir magnetically to dissolve it, thus obtaining a zinc sulfate solution; (3) Add sodium stannate to deionized water and stir magnetically to dissolve it, thus obtaining a sodium stannate solution; (4) Add the zinc sulfate solution from step (2) to the solution from step (1) and stir to mix evenly; (5) Slowly add the sodium stannate solution from step (3) to the mixed solution from step (4), and adjust the pH of the solution with ammonia water. Then stir the reaction at room temperature. After the reaction is completed, filter the solution and wash it with deionized water. Then dry it under vacuum, crush it, and sieve it to obtain the vermiculite-based flame retardant and smoke suppressant filler zinc hydroxystannate-encapsulated expanded vermiculite EVMT@ZHS.
2. The preparation method according to claim 1, characterized in that: The mass ratio of expanded vermiculite, zinc sulfate, and sodium stannate is 20:5.02:4.
66.
3. The preparation method according to claim 1, characterized in that: In step (4), the stirring time is 30 min and the stirring speed is 600 rpm.
4. The preparation method according to claim 1, characterized in that: In step (5), the solution pH is 9-10; the stirring reaction time is 4h, the stirring rate is 600 rpm; the vacuum drying temperature is 60 ℃, and the drying time is 12h.
5. A vermiculite-based flame-retardant and smoke-suppressing filler prepared by the method according to any one of claims 1-4.
6. The application of a vermiculite-based flame-retardant and smoke-suppressing filler prepared by the method according to any one of claims 1-4 in silicone foam, characterized in that: The preparation method of the silicone foam includes the following steps: by weight, 80 parts of vinyl silicone oil, 80 parts of hydroxyl silicone oil, 10 parts of water, and 2 parts of platinum catalyst are mixed and stirred evenly to obtain component A; 80 parts of vinyl silicone oil, 80 parts of hydroxyl silicone oil, 50 parts of hydrogen-containing silicone oil, 19 parts of zinc hydroxystannate-coated expanded vermiculite, and 2 parts of V4 inhibitor are mixed and stirred evenly to obtain component B; then component A and component B are mixed and stirred thoroughly for 60 s, foamed at room temperature for 15 min, and cured at 80°C for 2 h to obtain the silicone foam.