| 主权项 |
1: A process for producing an aerogel which comprises reacting the following components:
(a1) at least one polyfunctional isocyanate, (a2) from 5 to 20% by weight of at least one polyfunctional aromatic amine having the general formula I where R1 and R2 can be identical or different and are each selected independently from among hydrogen and linear or branched alkyl groups having from 1 to 6 carbon atoms and where all substituents Q1 to Q5 and Q1′ to Q5′ are identical or different and are each selected independently from among hydrogen, a primary amino group and a linear or branched alkyl group having from 1 to 12 carbon atoms, where the alkyl group can bear further functional groups, with the proviso that
the compound having the general formula I comprises at least two primary amino groups, where at least one of Q1, Q3 and Q5 is a primary amino group and at least one of Q1′, Q3′ and Q5′ is a primary amino group, andQ2, Q4, Q2′ and Q4′ are selected so that the aromatic amine having the general formula I has at least one linear or branched alkyl group having from 1 to 12 carbon atoms, which may optionally bear further functional groups, in the alpha position relative to at least one primary amino group bound to the aromatic ring, (a3) from 0 to 15% by weight of water, and (a4) from 1 to 4.9% by weight of at least one carboxylate as catalyst, in each case based on the total weight of the components (a1) to (a4), where the % by weight of the components (a1) to (a4) add up to 100% by weight, wherein the reaction is carried out in the presence of a solvent (C) which is removed under supercritical conditions after the reaction, wherein a gel is obtained in the reaction which is subsequently dried. |
