Method for preparing polyimide aerogel having low dielectric properties, high insulation, and high strength, and polyimide aerogel produced therefrom
The present invention relates to: a method for producing a polyimide aerogel having low dielectric properties, high insulation, and high strength; and a polyimide aerogel prepared therefrom. The present invention has the technical gist of a method for producing a polyimide aerogel having low dielectric properties, high insulation, and high strength, and a polyimide aerogel prepared therefrom, the method including: a first step of preparing a solvent; a second step of preparing a polyamic acid resin by reacting a diamine-based monomer with an acid anhydride monomer in a solvent; a third step of preparing a polyimide resin solution by imidizing the polyamic acid resin at 150 to 200° C.; a fourth step of preparing a polyimide wet gel by mixing a crosslinking agent and an acid with the polyimide resin solution; and a fifth step of preparing a polyimide aerogel by replacing the solvent contained in the polyimide wet gel with a main substitution solvent and a minor substitution solvent and then drying, wherein, in the fifth step, the main substitution solvent and the minor substitution solvent are each added to the polyimide wet gel in a stepwise manner to produce a polyimide aerogel having the porosity of 80 to 85 vol % while forming a skeletal structure having nano-pores through solvent-exchange.
1 . A method of manufacturing a polyimide aerogel having low dielectric constant, high insulation performance, and high strength, the method comprising:
a first step of preparing a solvent;
a second step of preparing a polyamic acid resin by reacting a diamine-based monomer and an acid anhydride monomer under the solvent;
a third step of preparing a polyimide resin solution by imidizing the polyamic acid resin at a temperature in a range of 150° C. to 200° C.;
a fourth step of preparing a polyimide wet gel by mixing a crosslinking agent and an acid with the polyimide resin solution; and
a fifth step of preparing a polyimide aerogel by replacing a solvent contained in the polyimide wet gel with a main substituent solvent and a sub-substituent solvent, and then drying the solvent,
wherein in the fifth step, the main substituent solvent and the sub-substituent solvent are added in a stepwise manner to the polyimide wet gel to replace the existing solvent in the polyimide wet gel, thereby producing a polyimide aerogel having a nano-pore skeletal structure and a porosity of 80% to 85% by volume.
2 . The method of claim 1 , wherein the solvent used in the first step has higher solubility for the polyimide resin solution used in the third step.
3 . The method of claim 1 , wherein the acid used in the fourth step may be one or more acids selected from among acetic acid, lactic acid, butyric acid, benzoic acid, citric acid, phosphoric acid, and hydrochloric acid.
4 . The method of claim 1 , wherein a Hansen solubility parameter (HSP) distance between the solvent of the polyimide resin solution and the main substituent solvent is equal to or greater than 14.
5 . The method of claim 1 , wherein an HSP distance between the solvent of the polyimide resin solution and the sub-substituent solvent is less than 14.
6 . The method of claim 1 , wherein the main substituent solvent comprises one or more solvents selected from among hexane, cyclohexane, octane, pentane, and perfluorohexane, and the sub-sub-substituent solvent is any one or more substituents selected from among toluene, tetrahydrofuran, cyclohexanone, and methyl isobutyl ketone.