Method for producing a molded heat-insulating element
View Patent ↗A process for producing an ammonia-treated hydrophilic thermal insulation molding which includes treating a thermal insulation molding containing hydrophilic silica with ammonia by introducing the thermal insulation molding into a chamber and supplying gaseous ammonia until a pressure difference Δp of ≥20 mbar is achieved. A process for producing a thermal insulation molding containing hydrophobic silica which includes treating the ammonia-treated hydrophilic thermal insulation molding with an organosilicon compound.
1. A process for producing an ammonia-treated hydrophilic thermal insulation molding, comprising treating a thermal insulation molding comprising hydrophilic silica with ammonia, such that the thermal insulation molding is introduced into a chamber and gaseous ammonia is supplied until a pressure difference Δp of ≥20 mbar is achieved.
2. The process of claim 1 , wherein a pressure in the chamber before introduction of the gaseous ammonia is below atmospheric pressure.
3. The process according to claim 1 , wherein the hydrophilic thermal insulation molding comprises up to 5 wt % water.
4. The process of claim 1 , further comprising introducing steam into the chamber.
5. The process of claim 1 , wherein the hydrophilic thermal insulation molding kept in the chamber for 1 to 100 hours starting from the point at which the gaseous ammonia is added.
6. The process of claim 1 , wherein a temperature in the chamber is between 0° C. and 100° C.
7. The process of claim 1 , wherein the hydrophilic silica is a fumed silica.
8. A process for producing a thermal insulation molding comprising hydrophobic silica, comprising treating the hydrophilic thermal insulation molding obtained by the process of claim 1 with an organosilicon compound.
9. The process of claim 8 , wherein the treatment with the organosilicon compound comprises introducing the hydrophilic thermal insulation molding treated with ammonia into a chamber and introducing a vaporous organosilicon compound into the chamber until a pressure difference Δp of ≥20 mbar is achieved.
10. The process of claim 9 , wherein the ammonia-treated hydrophilic thermal insulation molding comprises not more than 2 wt % water.
11. The process of claim 9 , wherein a pressure in the chamber before introduction of the organosilicon compound is below atmospheric pressure.
12. The process of claim 9 , wherein a temperature in the chamber is 20° C. to 300° C.
13. The process of claim 9 , wherein the ammonia-treated hydrophilic thermal insulation molding is kept in the chamber for 1 minute to 1 hour starting from the point at which the organosilicon compound is added.
14. A process for producing a thermal insulation molding comprising hydrophobic silica, the process comprising:
a) treating a thermal insulation molding comprising hydrophilic fumed silica with ammonia by introducing the molding into a chamber and supplying gaseous ammonia until a pressure difference Δp of ≥20 mbar is achieved,
b) subsequently treating the thus treated thermal insulation molding with (CH 3 ) 3 Si—NH—Si(CH 3 ) 3 thus forming ammonia, and
c) supplying the thus obtained ammonia, optionally with further ammonia, to another chamber in which a thermal insulation molding comprising hydrophilic fumed silica is disposed, wherein ammonia is supplied until a pressure difference Δp of ≥20 mbar is achieved.