Novel surface-modified MOF-doped flame-retardant smoke-suppression organic silicon foam and preparation method thereof

Abstract

The invention relates to the technical field of organic silicon foam materials, and provides a preparation method of novel flame-retardant smoke-suppression organic silicon foam doped with a surface-modified metal organic framework material. ZIF-8 powder in a surfactant modified MOF material is used as a powder filler for flame retardance and smoke suppression of organic silicon foam, fine and uniform modified MOF particles are used as nucleation centers for foaming in a section of vulcanization process after uniform mixing and coating, and foam pores are uniform and fine. On one hand, the modified ZIF-8 particles have super-strong adsorption and charring effects when subjected to high-temperature action; the porous structure of the ZIF-8 adsorbs smoke particles and harmful gas, and can decompose and absorb heat and isolate external heat at the same time; and on the other hand, metal compounds generated by pyrolysis in the combustion process participate in formation of a carbon layer, diffusion of smoke is prevented, metal oxides and some non-combustible gases can be generated, and the metal oxides block heat transmission while more external heat is absorbed.

Description

Technical Field

[0001] The invention relates to the technical field of silica gel foam materials, and in particular to a preparation method for a novel flame retardant and smoke suppressing organic silicon foam doped with a surface modified metal skeleton material and application thereof. Background Art

[0002] Metal Organic Framework (MOF) is a new type of porous polymer formed by the coordination of metal ions and organic ligands. It has the characteristics of large specific surface area, high pore density, and adjustable chemical structure. It is widely used in gas adsorption, catalysis, batteries, sensors and other fields. With the development of flame retardant technology, MOF materials with high thermal stability are gradually applied to the flame retardant field.

[0003] Silicone foam is a porous silicone foam material formed by mixing various silicone oils and silicone rubbers, reacting, dehydrogenating, foaming and cross-linking. Compared with other organic polymer foam materials, silicone foam not only has the characteristics of stable foam materials, non-toxic and waste-free, good softness, sound insulation and shock absorption, and excellent anti-aging compression effect, but also has excellent properties such as high thermal stability, high and low temperature resistance and good insulation of silicone. It is widely used in aerospace, new energy vehicles, 5G communications and rail transportation. However, since the silicone side chain belongs to a flammable polymer component and silicone rubber contains a large number of pore structures after foaming, the contact area between the material and the air increases, and it is easy to burn under high temperature or open flame conditions. At present, the flame retardant properties of silicone foam are improved and its fire hazard is reduced by adding various inorganic flame retardants to silicone foam. This type of flame retardant has problems such as poor flame retardant efficiency and large smoke generation. Therefore, finding new and efficient flame retardants is of great significance to improving the flame retardant and smoke suppression properties of silicone foam.

[0004] Specific implementation methods The following embodiments are further described in detail with reference to the embodiments of the present invention. The following embodiments are used to illustrate the present invention, but are not intended to limit the scope of the present invention. The embodiments described herein are part of the embodiments of the present invention, rather than all of the embodiments. It should be noted that, without departing from the technical principles of the present invention, several improvements and modifications may be made, and these improvements and modifications shall also be regarded as the protection scope of the present invention. Summary of the invention

[0005] The embodiment of the present invention provides a new flame retardant and smoke suppressing silicone foam doped with surface modified MOF, which is used to solve the problem of poor flame retardancy and large smoke during combustion of silicone foam, and can also improve its mechanical properties. The metal skeleton material modified by the surfactant has a uniform dry powder particle size, which is evenly distributed in the foamed foam after mixing.

[0006] The organosilicon foam is prepared from components A and B; The component A comprises the following raw materials in mass fractions: 10-50 parts of surface-modified ZIF-8 dry powder material, 5-30 parts of 50000-100000Pa·s methyl vinyl silicone rubber, 5-20 parts of 10000-20000Pa·s hydroxy silicone oil, 1-10 parts of 30-50Pa·s hydroxy silicone oil, 1-35 parts of fumed silica, and 1-2 parts of platinum catalyst; Component B comprises the following raw materials in mass fractions: 10-50 parts of surface-modified ZIF-8 dry powder material, 1-10 parts of hydrogenated silicone oil, 5-20 parts of 10000-20000Pa·s hydroxy silicone oil, 5-30 parts of 50000-100000Pa·s methyl vinyl silicone rubber, 1-35 parts of fumed silica, and 0.2-1 parts of inhibitor.

[0007] The preparation method of the surface-modified ZIF-8 dry powder material is as follows: 0.5-5 parts of a surfactant are added to an alcohol solution of dimethylimidazole and mixed evenly, and then a zinc salt solution is added, and the mixture is reacted under stirring for 5-10 hours. After the reaction is completed, the mixture is centrifuged, and the precipitate is collected and dried to obtain the surface-modified ZIF-8 powder.

[0008] The surfactant is selected from one or more of potassium perfluorobutyl sulfonate, silicone polyether, monolauryl phosphate, alkanolamide polyoxyethylene ether, and sulfosuccinamide ester.

[0009] The present invention also provides a method for preparing the novel flame retardant and smoke suppressing silicone foam, which comprises firstly preparing rubber materials A and B respectively and then stirring them, and then using a three-dimensional mixer to separate and evenly mix the rubber materials A and B components; The evenly mixed A and B rubber materials are weighed in a 1:1 ratio by mass, mixed, and quickly stirred to be evenly mixed. The mixture is placed between the release film materials. The corresponding calendering thickness is set according to the foaming ratio. After being flattened by double-roll calendering, the mixture is quickly placed in an oven. After vulcanization, the finished silicone foam is obtained.

[0010] The silicone foam undergoes two vulcanization processes, one vulcanization condition: temperature 80-100℃, time 10-30 min, and the second vulcanization condition: temperature 150-200℃, time 1-2 h.

[0011] In some specific embodiments, the technical solution adopted by the present invention is a method for preparing ZIF-8 powder doped with silicone foam before and after surface modification, and the specific steps are as follows: Step 1: Prepare ZIF-8 powder. Add zinc salt solution to the alcohol solution of dimethylimidazole, react for 5-10 hours under stirring. After the reaction is completed, centrifuge, collect the precipitate, and dry to obtain ZIF-8 powder.

[0012] Step 2: Preparation of surface-modified ZIF-8 powder: Add a surfactant to the alcohol solution of dimethylimidazole, mix well, add a zinc salt solution, and react for 5-10 hours under stirring. After the reaction is completed, centrifuge, collect the precipitate, and dry to obtain the surface-modified ZIF-8 powder.

[0013] Step 3: Add fumed silica to 10000-20000 Pa·s vinyl silicone oil, heat and mix in a kneader at 160-180° C., and then vacuum and stir to dehydrate for 2-4 hours to obtain a base rubber compound.

[0014] Step 4: Take the basic rubber obtained in step 3, add 50000-100000Pa·s methyl vinyl silicone rubber, 10000-20000Pa·s hydroxy silicone oil, 10000-20000Pa·s vinyl silicone oil, 30-50Pa·s hydroxy silicone oil and platinum catalyst, mix them evenly in a three-dimensional mixer, and finally obtain component A rubber.

[0015] Step 5: Take the base rubber obtained in step 3, add 50000-100000Pa·s methyl vinyl silicone rubber, 10000-20000Pa·s hydroxy silicone oil, 10000-20000Pa·s vinyl silicone oil, hydrogen-containing silicone oil and inhibitor, mix evenly in a three-dimensional mixer, and finally obtain component B rubber.

[0016] Step 6: Weigh the A and B component rubber materials of step 4 and step 5 in a ratio of 1:1, add equal masses of ZIF-8 powder to the A and B components respectively, mix them evenly in a three-dimensional mixer, and obtain the A and B component rubber materials doped with ZIF-8 powder respectively.

[0017] In the step 6, the mass ratio of the components A and B rubber to the ZIF-8 powder is 100:35-100:10.

[0018] Step 7: Weigh the A and B component rubber materials of step 4 and step 5 in a ratio of 1:1, add equal masses of surface-modified ZIF-8 powder to the A and B components respectively, mix them evenly in a three-dimensional mixer, and obtain the A and B component rubber materials doped with the surface-modified ZIF-8 powder respectively.

[0019] The mass ratio of the A and B components of the rubber materials in step 7 to the surface-modified ZIF-8 powder is 100:50 to 100:10. Step 8: The A and B component rubber materials obtained in step 6 or the A and B component rubber materials obtained in step 7 are fully mixed in a ratio of A and B components: 1:1, and then quickly separated from the film material, after being rolled and pulled by double rollers, they are placed in an oven (one sulfur condition: temperature 80-100°C, time 10-30 min, two sulfur conditions: temperature 150-200°C, time 1-2 h.) for foaming and cross-linking reaction, and then the ZIF-8 powder-doped silicone foam and the surface-modified ZIF-8 powder-doped silicone foam are obtained.

[0020] The present invention is also characterized in that: The surface area of ​​the ZIF-8 powder obtained in step 1 is 800-900 m 2 / g, its particle size is relatively uneven, the particle size D50 is 0.9μm, D90 is 4μm, and because it has not been modified by a surfactant, its powder surface: hydrophilicity> lipophilicity, which shows that in the experiment, the powder has poor compatibility with silicone oil, does not have good affinity and dispersibility, and at the same time cannot increase the amount of filler added, which is not conducive to improving the flame retardant and smoke suppression properties of silicone foam.

[0021] Surface-modified ZIF-8 powder in step 2: surface area 1200-1400 m 2 / g, the particle size is relatively uniform, the particle size D50 is 0.1-0.2μm, and the D90 is 0.4-0.5μm. Because the surfactant covers the surface of the powder filler particles, a layer of lipophilic cage structure can be formed, and the crystal growth will be restricted and stopped when it reaches a certain size. At the same time, the uniform and fine powder can improve the dispersibility of the filler in the rubber material, have better compatibility, make the powder filler and organic solvent silicone oil have good affinity, and can increase the addition amount of the powder filler, thereby improving the flame retardant and smoke suppression performance of the silicone foam.

[0022] The technical solution provided in this application has the following beneficial effects: by comparing MOF-doped silicone foam with undoped silicone foam before and after surface modification, the prepared surface-modified ZIF-8 powder-doped silicone foam has excellent flame retardant effect when subjected to high temperature or tearing or compression, and has obvious smoke suppression effect, and its mechanical properties are significantly better than those of ZIF-8 powder-doped silicone foam and undoped silicone foam. In addition, the raw material cost of surface-modified ZIF-8 powder is low, and the process operation is simple, which is suitable for mass production. DETAILED DESCRIPTION

[0023] The present application provides a method for preparing a novel flame-retardant and smoke-suppressing silicone foam doped with surface-modified MOF, wherein the method for preparing the MOF before and after surface modification specifically comprises the following steps: Preparation of ZIF-8 powder: Use 50 ml of methanol and distilled water as solvents A and B, add 50 parts of Zn(NO3)2·6H2O as A, and 50 parts of dimethylimidazole as B. After the solutes in A and B are completely dissolved, add solution A to solution B under magnetic stirring and stir and mix, and continue stirring at room temperature for 5 h. After the reaction is completed, centrifuge the solution with a high-speed centrifuge (8000 rpm, 3 min), collect the precipitate, wash it with methanol 3 times, and then dry it in a vacuum oven at 50 ° C for 12 h to obtain ZIF-8 powder.

[0024] Preparation of surface-modified ZIF-8 powder: 100 ml of methanol and distilled water were used as solvents A and B, 50 parts of Zn(NO3)2·6H2O were added as A, 50 parts of dimethylimidazole material were added as B, and 5 parts of surfactant were added to B and mixed evenly. After the solutes in A and B were completely dissolved, solution A was added to solution B under magnetic stirring and stirred, and continued to stir at room temperature for 5 h. After the reaction was completed, the solution was centrifuged in a high-speed centrifuge (8000 rpm, 3 min), the precipitate was collected, washed with methanol 3 times, and then dried in a vacuum oven at 50 °C for 12 h to obtain surface-modified ZIF-8 powder.

[0025] In the preparation of the surface-modified ZIF-8 powder, the surfactant is selected from one or more of potassium perfluorobutyl sulfonate, silicone polyether, monolauryl phosphate, alkanolamide polyoxyethylene ether, and sulfosuccinamide ester to obtain the corresponding surfactant-modified ZIF-8 powder.

[0026] Example 1 Step 1: Calculate by mass fraction, add 200 parts of a 100 m2-specific surface area to 800 parts of 20,000 Pa·s vinyl silicone oil. 2 / g fumed silica, heated at 170°C in a kneader for 2h, vacuum-stirred and dehydrated for 4h to obtain a basic rubber material with a viscosity of 300000Pa·s.

[0027] Step 2: Preparation of component A rubber: Add 35 parts of the basic rubber obtained in step 1, 5 parts of 100000Pa·s methyl vinyl silicone rubber, 10 parts of 20000Pa·s hydroxyl silicone oil, 14 parts of 20000Pa·s vinyl silicone oil, 15 parts of 40Pa·s hydroxyl silicone oil, and 1.6 parts of platinum catalyst (5000ppm) in proportion by mass, mix evenly in a three-dimensional mixer, then add 9 parts of ZIF-8 dry powder surface-modified with potassium perfluorobutylsulfonate, mix evenly again to obtain component A rubber doped with surface-modified ZIF-8 powder.

[0028] Step 3: Take 35 parts of the base rubber obtained in step 1, calculate the mass fraction, add 5 parts of 100000Pa·s methyl vinyl silicone rubber, 10 parts of 20000Pa·s hydroxyl silicone oil, 20 parts of 20000Pa·s vinyl silicone oil, 10 parts of hydrogenated silicone oil (hydrogen content 1.5%), and 0.8 parts of inhibitor, mix them evenly in a three-dimensional mixer, then add 9 parts of ZIF-8 dry powder surface-modified with potassium perfluorobutylsulfonate, mix again to obtain the B component rubber doped with surface-modified ZIF-8 powder.

[0029] Step 4: Mix the A and B rubber materials prepared in steps 2 and 3 in a mass ratio of 1:1, and put them between the release film materials after rapid stirring. The foam thickness is set according to the foaming ratio. After double-roller calendering and flattening, quickly put them into the oven for a vulcanization foaming reaction at an oven temperature of 90°C for 30 min; then carry out a secondary vulcanization cross-linking reaction at an oven temperature of 180°C for 70 min. After the second stage of vulcanization, a surface-modified MOF-doped new flame-retardant and smoke-suppressing finished silicone foam is obtained.

[0030] Example 2 The difference between Example 2 and Example 1 is that the surfactant-modified ZIF-8 powder in components A and B is replaced by 20 parts of potassium perfluorobutanesulfonate surface-modified ZIF-8 dry powder.

[0031] Example 3 The only difference between Example 3 and Example 1 is that the ZIF-8 powder modified with surfactant in components A and B is replaced with ZIF-8 dry powder surface-modified with 35% potassium perfluorobutanesulfonate.

[0032] Example 4 The only difference between Example 4 and Example 1 is that the surfactant-modified ZIF-8 powder in components A and B is replaced by 54 parts of potassium perfluorobutanesulfonate-modified ZIF-8 dry powder.

[0033] Example 5 Example 5 is different from Example 1 only in that instead of adding 9 parts of ZIF-8 dry powder to the surfactant-modified ZIF-8 powder in components A and B, 9 parts of ZIF-8 dry powder are added to each component.

[0034] Example 6 The difference between Example 6 and Example 1 is that 20 parts of ZIF-8 dry powder are added to each of the surfactant-modified ZIF-8 powders in the A and B components.

[0035] Example 7 The steps of Example 7 are the same as those of Example 1, except that 54 parts of ZIF-8 dry powder surface-modified with sulfosuccinamide ester are added to the ZIF-8 dry powder surface-modified with another surfactant, sulfosuccinamide ester, at the same molar mass.

[0036] Example 8 The steps of Example 8 are the same as those of Example 1, except that 54 parts of ZIF-8 dry powder surface-modified with alkanolamide polyoxyethylene ether are added to the surface of the ZIF-8 dry powder with the same molar mass as another surfactant alkanolamide polyoxyethylene ether.

[0037] Comparative Example 1 Step 1: Calculate by mass fraction, add 200 parts of a 100 m2-specific surface area to 800 parts of 20,000 Pa·s vinyl silicone oil. 2 / g fumed silica, heated at 170°C in a kneader for 2h, vacuum-stirred and dehydrated for 4h to obtain a basic rubber compound.

[0038] Step 2: Preparation of component A rubber: Add 35 parts of the base rubber obtained in step 1, 5 parts of 100000Pa·s methyl vinyl silicone rubber, 10 parts of 20000Pa·s hydroxyl silicone oil, 14 parts of 20000Pa·s vinyl silicone oil, 15 parts of 40Pa·s hydroxyl silicone oil, and 1.6 parts of platinum catalyst (5000ppm) in proportion by mass, mix them evenly in a three-dimensional mixer, and finally obtain the component A rubber without MOF doping.

[0039] Step 3: Take 35 parts of the base rubber obtained in step 1, calculate the mass fraction, add 5 parts of 100000Pa·s methyl vinyl silicone rubber, 10 parts of 20000Pa·s hydroxyl silicone oil, 20 parts of 20000Pa·s vinyl silicone oil, 10 parts of hydrogen-containing silicone oil (hydrogen content 1.5%), and 0.8 parts of inhibitor, mix them evenly in a three-dimensional mixer, and finally obtain the B component rubber without MOF doping.

[0040] Step 4: Mix the A and B rubber materials prepared in steps 2 and 3 in a mass ratio of 1:1, and put them between the release film materials after rapid stirring. The foam thickness is required to set the corresponding calendering thickness according to the foaming ratio. After double-roller calendering and flattening, quickly put them into the oven for a primary vulcanization foaming reaction at an oven temperature of 90°C for 30 min; then carry out a secondary vulcanization cross-linking reaction at an oven temperature of 180°C for 70 min. After the second stage of vulcanization, a silicone foam without flame retardant is obtained.

[0041] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that the surfactant-modified ZIF-8 powder in components A and B is replaced by 81 parts of potassium perfluorobutanesulfonate-modified ZIF-8 dry powder.

[0042] Comparative Example 3 Comparative Example 3 is different from Example 5 only in that 35 parts of ZIF-8 dry powder are added to each of the A and B components instead of the surfactant-modified ZIF-8 powder.

[0043] Comparative Example 4 Comparative Example 4 is different from Example 5 only in that 54 parts of ZIF-8 dry powder are added to each of the A and B components instead of the surfactant-modified ZIF-8 powder.

[0044]

[0045] Table 1: Mechanical properties test results of novel flame retardant and smoke suppressing silicone foams prepared in Examples 1-8 and Comparative Examples 1-4 Table 2: Test results of flame retardant and smoke suppression properties of novel flame retardant and smoke suppression silicone foams prepared in Examples 1-8 and Comparative Examples 1-4

[0046] As can be seen from Tables 1 and 2, for the samples prepared in Examples 1-8, Comparative Example 1, and Comparative Examples 2-6, as the surfactant-modified ZIF-8 powder is added, its tensile strength and limiting oxygen index (LOI) performance increase with the increase of the added amount; the elongation at break decreases with the increase of the added amount; the peak smoke generation rate and the smoke generation within 600s decrease with the increase of the added amount. From the results, it can be seen that the addition of surfactant-modified ZIF-8 powder has a significant improvement on the flame retardancy and smoke suppression properties of silicone foam.

[0047] The test results of Examples 1-4 and Comparative Examples 5 and 6 show the difference in the improvement of the organosilicon foam by MOF doping before and after surfactant modification. It is obvious that the MOF modified by surfactant has a greater improvement on the performance of the organosilicon foam system. The reason is that the surface-modified ZIF-8 powder modified by surfactant has a larger surface area, a more uniform particle size, and a fine powder that is much smaller than the ZIF-8 before modification. It has higher thermal stability and better flame retardant performance. The surfactant covers the surface of the powder filler particles to form a layer of oleophilic mesh cage structure, improves the dispersibility of the ZIF-8 powder as a filler in the rubber material, has better compatibility, makes the powder filler and the organic solvent silicone oil have good affinity, and can increase the amount of powder filler added. When subjected to high temperature, MOF powder is filled in the organosilicon foam to greatly suppress the dispersion of smoke, and when the ZIF-8 powder decomposes, it generates metal oxides with extremely high melting points and absorbs a large amount of heat, so that the organosilicon foam has excellent flame retardancy, thereby improving the flame retardant and smoke suppression performance of the organosilicon foam.

[0048] The test results of Example 4 and Comparative Examples 6 and 7 show that different types of surfactants have flame retardant, smoke suppression and dispersing effects. Although the flame retardant, smoke suppression and dispersing effects of silicone foam are positively improved compared with ZIF-8 powder without surfactant modification, there are still certain differences in specific surfactant substances.

[0049] The above embodiments do not limit the present invention in any form, and any technical solutions obtained by equivalent replacement or equivalent transformation shall fall within the protection scope of the present invention.

Claims

1. A novel flame retardant and smoke suppressing silicone foam doped with surface modified MOF, characterized in that: The organosilicon foam is prepared from components A and B; The component A comprises the following raw materials in mass fractions: 10-50 parts of surface-modified ZIF-8 dry powder material, 5-30 parts of 50000-100000Pa·s methyl vinyl silicone rubber, 5-20 parts of 10000-20000Pa·s hydroxy silicone oil, 1-10 parts of 30-50Pa·s hydroxy silicone oil, 1-35 parts of fumed silica, and 1-2 parts of platinum catalyst; Component B comprises the following raw materials in mass fractions: 10-50 parts of surface-modified ZIF-8 dry powder material, 1-10 parts of hydrogenated silicone oil, 5-20 parts of 10000-20000Pa·s hydroxy silicone oil, 5-30 parts of 50000-100000Pa·s methyl vinyl silicone rubber, 1-35 parts of fumed silica, and 0.2-1 parts of inhibitor.

2. The surface-modified MOF-doped novel flame-retardant and smoke-suppressing silicone foam according to claim 1, characterized in that: The preparation method of the surface-modified ZIF-8 dry powder material is as follows: adding a surfactant to an alcohol solution of dimethylimidazole and mixing evenly, then adding a zinc salt solution, reacting for 5-10 hours under stirring, and after the reaction is completed, centrifuging, collecting the precipitate, and drying to obtain the surface-modified ZIF-8 powder.

3. The novel flame retardant and smoke suppressing silicone foam doped with surface modified MOF according to claim 2, characterized in that: The surface modified surfactant has a flame retardant and smoke suppressing effect and also has a dispersing effect, and its addition amount is 0.5-5 parts; The surfactant is selected from one or more of potassium perfluorobutyl sulfonate, silicone polyether, monolauryl phosphate, alkanolamide polyoxyethylene ether, and sulfosuccinamide ester.

4. The novel flame retardant and smoke suppressing silicone foam doped with surface modified MOF according to claim 2 or 3, characterized in that: The surface area of ​​the surface-modified ZIF-8 powder prepared is 1200-1400 m 2 / g, and the grain size is 0.1~0.5μm.

5. A method for preparing the novel flame retardant and smoke suppressing silicone foam according to any one of claims 1 to 4, characterized in that: First, prepare the A and B rubber materials respectively and stir them, and then use a three-dimensional mixer to evenly mix the A and B component rubber materials separately; The evenly mixed A and B rubber materials are weighed in a 1:1 ratio by mass, mixed, and quickly stirred to be evenly mixed. The mixture is placed between the release film materials. The corresponding calendering thickness is set according to the foaming ratio. After being flattened by double-roll calendering, the mixture is quickly placed in an oven. After vulcanization, the finished silicone foam is obtained.

6. The preparation method according to claim 5, characterized in that: The silicone foam undergoes two vulcanization processes, one vulcanization condition: temperature 80-100℃, time 10-30 min, and the other vulcanization condition: temperature 150-200℃, time 1-2 h.

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