Composition comprising silyl derivative as dehydrating agent
Disclosed is a compositions comprising isocyanate sub-composition comprising by weight not more than 5% of diisocyanate monomers, a dehydrating agent selected among compounds bearing dihydrocarbylsilyl groups bonded to a metalloid of the chalcogen column or to an atom of the nitrogen column. The invention is applicable to the coatings industry, in particular paints and adhesives.
1. A composition comprising at least one isocyanate sub-composition, having at most 5% by weight of diisocyanate monomers, at least one dehydrating agent of formula
wherein Z is a hydrocarbyl, a silanoxanyl or a silazanyl group, Hc and Hc′ independently are a hydrocarbyl group having at most 15 carbon atoms, v is 0 or 1, and Y is
i) an amino group, optionally having a substituent selected from the group consisting of a residue of an oxygen acid after elimination of a hydroxyl group, a hydrocarbyl group, a trihydrocarbylsilyl group, and a group of formula
wherein Hc o , Hc o ′ and Z′ are as previously defined for Hc, Hc′ and Z,
or
ii) a selenium, sulfur or oxygen atom, having a substituent being a residue of an oxygen acid after elimination of a hydroxyl group,
and
at least one non-alkylatable organic or inorganic base, being an at least partially aromatic tertiary amine or tertiary phosphine, in an amount corresponding to at least 0.1 times the amount of dihydrocarbylsilylene, when expressed as silicon atom equivalents.
2. A composition according to claim 1 , said sub-composition comprising at most 2% by weight of diisocyanate monomers.
3. A composition according to claim 1 , said sub-composition comprising at most 1% by weight of diisocyanate monomers.
4. A composition according to claim 1 , said oxygen acid being a carboxylic, a hydrocarbyl sulfuric, a sulfonic, a sulfonic, a phosphoric, a phosphonic or a phosphinic acid.
5. A composition according to claim 1 , said base being present in an amount corresponding to at least 2 times the amount of dihydrocarbylsilylene, when expressed as silicon atom equivalents.
6. A composition according to claim 1 , said composition additionally comprising a polyfunctional sub-composition having abstractable hydrogens.
7. A composition according to claim 1 , said composition additionally comprising at least one surface active agent.
8. A composition according to claim 1 , said composition additionally comprising a solvent.
9. A composition according to claim 8 , said solvent being a hygroscopic solvent having a polar functional group.
10. A composition according to claim 1 , said dehydrating agent being selected from the group consisting of bis-trimethylsilylacetamide, bis-trimethylsilylurea, hexamethyldisilazane and trimethylsilylphosphate.