초록 ▼

Thermally insulative xerogels and their preparation are described. To obtain these xerogels, an inorganic gel having hydroxyl moieties is reacted with a silicon-nitrogen compound which has a C.sub.1-6 hydrocarbon moiety on the silicon. Shrinkage of the gel during drying the gel is reduced and a more

Thermally insulative xerogels and their preparation are described. To obtain these xerogels, an inorganic gel having hydroxyl moieties is reacted with a silicon-nitrogen compound which has a C.sub.1-6 hydrocarbon moiety on the silicon. Shrinkage of the gel during drying the gel is reduced and a more highly porous xerogel is obtained. The more highly porous xerogel has a low thermal conductivity which makes it a good thermal insulation.

대표청구항 ▼

[ What is claimed is:] [14.] Thermal insulation which comprises a xerogel having a thermal conductivity less than 0.031 watts per meter per degree kelvin at ambient temperatures, a bulk density less than about 0.45 g/cm.sup.3 and a porosity greater than about 60%, the xerogel further having moieties

[ What is claimed is:] [14.] Thermal insulation which comprises a xerogel having a thermal conductivity less than 0.031 watts per meter per degree kelvin at ambient temperatures, a bulk density less than about 0.45 g/cm.sup.3 and a porosity greater than about 60%, the xerogel further having moieties of --O--Si(C.sub.1-6)(R.sup.2).sub.2 where each R.sup.2 can independently be a C.sub.1-6 moiety or an N(R.sup.1).sub.2 moiety in which each R.sup.1 can independently be a hydrogen, a C.sub.1-6 moiety, or a Si(C.sub.1-6).sub.3 moiety, further providing that each of the C.sub.1-6 moieties can have from 1 to 6 carbon atoms and can be a linear, branched or cyclic, saturated, unsaturated or aromatic hydrocarbon moiety having only hydrogen as a substituent, the said xerogel having the --O--Si(C.sub.1-6)(R.sup.2).sub.2 moieties present at an amount of at least about 0.5 mole percent further providing that the xerogel is a reaction product between an inorganic wet gel having a solid structure containing hydroxyl moieties, the said wet gel having 5% or less by weight of water and being wet with a fluid phase which includes a polar or non-polar hydrocarbon solvent, and a silicon-nitrogen compound which had the formulation of (Si(C.sub.1-6)(R.sup.2).sub.z --N(R.sup.1).sub.y).sub.x where x can be any whole number from 1 to 20, z can be 1 or 2, and y can be 1 or 2, where the said silicon-nitrogen compound can be linear, branched, cyclic or contain cyclic sections.