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CN-121758979-B - Microporous silica gel material based on supercritical foaming and preparation method thereof

CN121758979BCN 121758979 BCN121758979 BCN 121758979BCN-121758979-B

Abstract

The invention discloses a microporous silica gel material based on supercritical foaming and a preparation method thereof, wherein the microporous silica gel material comprises, by weight, 100 parts of silicon rubber, 1-3 parts of active zinc oxide, 20-40 parts of modified nano silicon dioxide, 2-4 parts of vulcanizing agent and 2-4 parts of vulcanization accelerator, the modifying agent of the modified nano silicon dioxide is cage-shaped polysilsesquioxane containing a silicon hydroxyl structure, the microporous silica gel material is prepared through the steps of pre-mixing, re-mixing, pre-vulcanizing, supercritical foaming, re-vulcanizing shaping and irradiation sterilization, the tensile strength of the microporous silica gel material can reach 5.8-6.9 MPa, the pore shape after foaming is uniform, the pores are not broken, the average pore diameter is 50-60 microns, the mechanical property is strong, the flame retardant level reaches over V-1, and the microporous silica gel material does not have abnormal change after being irradiated by high-energy electron beams.

Inventors

  • WU FENGHUA

Assignees

  • 厦门舜芯新材料有限公司

Dates

Publication Date
20260508
Application Date
20260302

Claims (10)

  1. 1. The microporous silica gel material based on supercritical foaming is characterized by comprising, by weight, 100 parts of silicon rubber, 1-3 parts of active zinc oxide, 20-40 parts of modified nano silicon dioxide, 2-4 parts of vulcanizing agent and 2-4 parts of vulcanization accelerator; wherein, the active zinc oxide is prepared by activating zinc oxide powder, and the activating steps are as follows: Adding 10 parts of a pre-prepared mixed solution of acetic acid and ethanol into zinc oxide powder, dispersing in a ball mill for 2-4 hours at the rotating speed of 20-50 rpm to obtain a mixed zinc oxide powder slurry, placing the zinc oxide powder slurry in a high-pressure steam pot, introducing high-pressure steam, sealing, rolling and steaming for 4-8 hours, decompressing the high-pressure steam pot, simultaneously introducing steam and nitrogen into the high-pressure steam pot according to the volume ratio of 1:1, heating and purging the zinc oxide powder slurry for 1-2 hours, removing ethanol and residual acetic acid in the zinc oxide powder slurry, placing the zinc oxide powder slurry after removing the ethanol and the residual acetic acid into a muffle furnace, calcining for 2-4 hours at the temperature of 300-400 ℃ to obtain the calcined zinc oxide powder, naturally cooling in the muffle furnace, and sieving with a nylon screen of 1500-2500 meshes to obtain active zinc oxide; Wherein the modified nano silicon dioxide is prepared by the following steps: S1, drying white carbon black in a vacuum oven at 100-150 ℃ to constant weight, and uniformly stirring and mixing the dried white carbon black and dehydrated toluene according to the mass ratio of 1:5-10 to obtain a first mixed solution; S2, adding a modifying agent of cage-shaped polysilsesquioxane containing a silicon hydroxyl structure into the first mixed solution under the protection of nitrogen, mixing by ultrasonic vibration at the temperature of 30-40 ℃, adding a catalyst at the weight of 0.5-2 wt% based on the weight of the white carbon black, heating the system to 90-110 ℃, carrying out reflux reaction for 5-12 h at the temperature, and filtering the suspension after the reaction is finished to obtain the filtered white carbon black; S3, filtering the white carbon black, washing the white carbon black with absolute ethyl alcohol for 3-4 times, removing toluene solvent and catalyst, and then drying the white carbon black to constant weight in vacuum at 80-90 ℃ to obtain dry white carbon black; s4, grinding the dry white carbon black, and sieving through a nylon screen with a mesh of 1000-2500 to obtain modified nano silicon dioxide; the silicone rubber is one of methyl vinyl silicone rubber and phenyl silicone rubber; in the step S1, the white carbon black is gas phase white carbon black, the particle size of the white carbon black is 20-50 nm, and the specific surface area of the white carbon black is 200-300 m <2 >/g; In step S2, the modifier is one of trisilanolphenyl cage polysilsesquioxane or trisilanolisooctyl cage polysilsesquioxane.
  2. 2. The microporous silica gel material based on supercritical foaming according to claim 1, wherein in the step of activating active zinc oxide, the air pressure of the air flow mill is 0.4-0.6 mpa.
  3. 3. The microporous silica gel material based on supercritical foaming according to claim 1, wherein in the step of activating active zinc oxide, the mixed solution of acetic acid and ethanol is prepared according to a weight ratio of 1:10-20.
  4. 4. The microporous silica gel material based on supercritical foaming according to claim 1, wherein in the step of activating active zinc oxide, the internal pressure of the high-pressure steam pot is 1.5-2.5 mpa, and the temperature of the high-pressure steam pot is maintained at 110-130 ℃ after heating.
  5. 5. The microporous silica gel material based on supercritical foaming according to claim 1, wherein in the step S1, the dehydrated toluene is prepared by putting a molecular sieve into a toluene solvent, mixing by ultrasonic vibration at a solvent temperature of 30-40 ℃ for 1-2 hours, and filtering after mixing to obtain the dehydrated toluene with a water content of 100-200 ppm.
  6. 6. The microporous silica gel material according to claim 1, wherein in step S2, the catalyst is one or both of triethylamine and dibutyltin dilaurate.
  7. 7. The microporous silica gel material based on supercritical foaming according to claim 1, wherein the vulcanizing agent is one or more of dicumyl peroxide, dibenzoyl peroxide and tert-butyl peroxybenzoate.
  8. 8. The microporous silica gel material based on supercritical foaming according to claim 1, wherein the vulcanization accelerator is one or more of dicyclohexylsulfenamide, diphenylguanidine, 2-mercaptobenzothiazole or cadmium carbamate.
  9. 9. The method for preparing the microporous silica gel material based on supercritical foaming according to any one of claims 1 to 8, which is characterized by comprising the following steps: firstly, premixing, namely taking 100 parts of silicon rubber and 20-40 parts of modified nano silicon dioxide according to a proportion, mixing in a mixer for 20-40 min to obtain a mixed material, and standing the mixed material for 3-5 days at room temperature; Mixing, namely adding 2-4 parts of vulcanizing agent, 1-3 parts of active zinc oxide and 2-4 parts of vulcanization accelerator into the mixed material according to the proportion, mixing for 15-30 min in an internal mixer, starting vacuumizing, continuously mixing for 15-30 min in the vacuumizing process, controlling the internal pressure to be lower than 1000Pa, discharging after 2-4 h to obtain a mixed material, and standing the mixed material for 1-2 days at 4-10 ℃ to prepare the mixed material for later use; Step three, pre-vulcanizing, namely injecting the mixed material into a mold by using a rubber injection molding machine, heating the mold to 110-125 ℃, increasing the pressure in the mold by 8-16 MPa, vulcanizing for 120-250 s, and then decompressing the mold to normal pressure and rapidly cooling to obtain a pre-vulcanized product with a fixed shape and a primary cross-linked three-dimensional structure; Introducing supercritical fluid into a die, heating the die to 80-110 ℃ and immersing for 20-60 min under the condition of 15-30 MPa, and rapidly reducing the pressure in the die to normal pressure within 1-2 s, wherein the reducing rate is used for initiating the expansion of saturated gas, so as to obtain a vulcanized product with a uniform and stable cell structure; Step five, vulcanizing and shaping, namely quickly raising the temperature of the die to 135-150 ℃ to completely vulcanize the foamed silica gel, and continuously pumping air to the die in the re-vulcanization process to keep the pressure in the die at a low vacuum of 0.03-0.05 MPa for 30-60 min to obtain the microporous silica gel material; Step six, irradiation sterilization, namely sterilizing the prepared microporous silica gel material by high-energy electron beam irradiation under the condition of nitrogen protection, wherein the irradiation dose of the high-energy electron beam is controlled to be 15-20 kGy, and the irradiation time is 3-6 s, so as to prepare the sterilized microporous silica gel material; in the fourth step, the supercritical fluid is a mixed gas of carbon dioxide and nitrogen.
  10. 10. The method for preparing the microporous silica gel material based on supercritical foaming according to claim 9, wherein, In the fourth step, the volume ratio of the nitrogen to the carbon dioxide is 1:4.

Description

Microporous silica gel material based on supercritical foaming and preparation method thereof Technical Field The invention relates to the technical field of microporous silica gel material production, in particular to a microporous silica gel material based on supercritical foaming and a preparation method thereof. Background The porous silica gel material of supercritical foaming has good heat insulation effect due to the porous structure of the material, but the porous structure material has the problem of low mechanical strength compared with the material of a solid structure, in order to improve the mechanical strength of the microporous silica gel material of the material, a certain amount of reinforcing filler such as white carbon black (including gas phase white carbon black or precipitation white carbon black) is added into the silica gel material, but the filling amount of the white carbon black is too high, so that the processing difficulty of the sizing material can be greatly increased, moreover, the reinforcing filler is easy to generate agglomeration phenomenon in the processing process, the reinforcing filler is agglomerated and unevenly dispersed in the interior of the material, the quality of cells is poor when the silica gel is foamed, such as the size difference of the cells is too large, the cells are uneven, obvious cell merging phenomenon is caused, and the defects of the cells such as the size difference of the cells is too large, the cells are uneven easily cause uneven stress of each cell during the use process, the stress concentration phenomenon appears, so that the mechanical property of the microporous silica gel material is reduced. Therefore, in the preparation and production process of the supercritical foaming microporous silica gel material, the problem of agglomeration of the reinforcing filler in the material is prevented, the uniformity of cells is improved, the problem of overlarge cell size difference is avoided, and the problem of improving the mechanical property of the supercritical foaming microporous silica gel material foaming material is solved. Disclosure of Invention Based on the defects in the prior art, the invention aims to provide a microporous silica gel material based on supercritical foaming and a preparation method thereof, and the reinforced filler is improved, so that the problem of agglomeration of the reinforced filler in silicon rubber is solved, uniform cells of the silica gel foaming material are obtained after supercritical foaming molding, and the mechanical property of the microporous silica gel material is improved. In order to achieve the above object, the present invention is realized by the following technical scheme: The microporous silica gel material based on supercritical foaming comprises, by weight, 100 parts of silicon rubber, 20-40 parts of modified nano silicon dioxide, 1-3 parts of active zinc oxide, 2-4 parts of vulcanizing agent and 2-4 parts of vulcanization accelerator; wherein, the active zinc oxide is prepared by activating zinc oxide powder, and the activating steps are as follows: Adding 10 parts of a pre-prepared mixed solution of acetic acid and ethanol into zinc oxide powder, dispersing in a ball mill for 2-4 hours at the rotating speed of 20-50 rpm to obtain a mixed zinc oxide slurry, placing the zinc oxide slurry in a high-pressure steam pot, introducing high-pressure steam, sealing, rolling and steaming for 4-8 hours, decompressing the high-pressure steam pot, simultaneously introducing steam and nitrogen into the high-pressure steam pot according to the volume ratio of 1:1, heating and purging the zinc oxide slurry for 1-2 hours, removing ethanol and residual acetic acid in the zinc oxide slurry, placing the zinc oxide slurry after removing the ethanol and the residual acetic acid in a muffle furnace, calcining for 2-4 hours at the temperature of 300-400 ℃ to obtain the calcined zinc oxide powder, naturally cooling in the muffle furnace, and sieving with a 1500-2500 mesh nylon screen to obtain active zinc oxide; Wherein the modified nano silicon dioxide is prepared by the following steps: s1, drying white carbon black in a vacuum oven at 100-150 ℃ to constant weight, and uniformly stirring and mixing the dried white carbon black and dehydrated toluene according to the mass ratio of 1 (5-10) to obtain a first mixed solution; S2, adding a modifying agent of cage-shaped polysilsesquioxane containing a silicon hydroxyl structure into the first mixed solution under the protection of nitrogen, mixing by ultrasonic vibration at the temperature of 30-40 ℃, adding a catalyst at the weight of 0.5-2 wt% based on the weight of the white carbon black, heating the system to 90-110 ℃, carrying out reflux reaction for 5-12 h at the temperature, and filtering the suspension after the reaction is finished to obtain the filtered white carbon black; S3, filtering the white carbon black, washing the white carbon black with absolute e