Organosiliconate powders, method for the production thereof and use thereof for hydrophobizing mineral building materials
Solid alkali metal salts of organosilanols and/or their hydrolysis/condensation products are prepared by hydrolysis of organosilanes in water and in the presence of a basic alkali metal salt. The products contain predominately methyl and ethyl organic groups, and C 4 or higher hydrocarbon groups as well. The solid salts effectively hydrophobe building materials, while being easily mixed with water.
1. Solid salts of organo radical-containing organosilanols, of their hydrolysis/condensation products, or of organo radical-containing organosilanols together with their hydrolysis/condensation products, with alkali metal cations, wherein the molar ratio of cation to silicon is 0.5 to 3, wherein at least 1 mol % and not more than 99 mol % of the organo radicals are selected from the group consisting of methyl and ethyl radicals and mixtures thereof, and organo radicals other than methyl and ethyl radicals contain at least 4 C atoms, produced by a process, comprising:
in a first step, hydrolyzing organosilanes of the formula 1
(R 1 ) a Si(Y) b (—Si(R 2 ) 3-c (Y) c ) d (1)
or their hydrolysis/condensation products, or the organosilanes of the formula 1 together with their hydrolysis/condensation products,
where
R 1 and R 2 are each a monovalent, Si—C-bonded C 1-30 hydrocarbon radical which is unsubstituted or is substituted by halogen atoms, amino groups, thiol groups or C 1-6 alkyl- or C 1-6 alkoxy-substituted silyl groups, in which one or more nonadjacent —CH 2 — units are optionally replaced by groups —O—, —S—, or —NR 3 —, and in which one or more nonadjacent ═CH— units are optionally replaced by groups —N═,
R 3 is hydrogen or a monovalent C 1-8 hydrocarbon radical which is unsubstituted or substituted by halogen atoms or NH 2 groups,
Y is H, F, Cl, Br, or OR 4 ,
R 4 is a monovalent C 1-10 hydrocarbon radical which is unsubstituted or substituted by halogen atoms or silyl groups, in which one or more nonadjacent CH 2 units are optionally replaced by groups —O—, —S—, or —NR 3 —, and in which one or more nonadjacent ═CH— units are optionally replaced by groups —N═,
a is 1, 2 or 3, and
b, c, and d are 0, 1, 2 or 3,
with the proviso that b+c≧1 and a+b+d=4,
in the presence of water and basic salt of alkali metal cations,
the amount of basic salt being calculated such that per mole of silicon there is 0.5 mol to 3 mol of cations, and, if the organosilanes of the formula 1 contain F, Cl, and/or Br radicals, a further mole of basic salt is present per mole of F, Cl, and Br, and
in a second step, removing liberated compound(s) HY, in the form of gas,
in a third step, removing water present in the mixture, and in a fourth step, isolating the salt in the form of a solid,
wherein at least 1% and not more than 99% of the radicals R 1 and R 2 are methyl and/or ethyl radicals and radicals R 1 and R 2 which are not methyl or ethyl radicals contain at least 4 C atoms.
2. The solid salts of claim 1 , in which 10% to 90% of all organic radicals are methyl radicals and/or ethyl radicals.
3. The solid salts of claim 1 , in which all organic radicals are hydrocarbon radicals having 1 to 8 carbon atoms.
4. A hydrophobizing composition, comprising a solid salt of claim 1 .
5. A process for hydrophobing a mineral substance, building material, or fibrous substance, comprising adding a solid salt of claim 1 .
6. A building material in powder form, comprising a solid salt of claim 1 .