Process for preparing polyisocyanates which are flocculation-stable in solvents from (cyclo)aliphatic diisocyanates

摘要

The present invention relates to a new process for preparing polyisocyanates containing isocyanurate groups and being flocculation-stable in solvents from (cyclo)aliphatic diisocyanates.

主权项

1. A method for reducing flocculation and/or precipitation in a polyisocyanate mixture, the method comprising mixing the polyisocyanate mixture with an additive, wherein said mixing is carried out in the presence of water and a solvent, thereby reducing flocculation, precipitation, or both, of the polyisocyanate mixture, and
wherein the additive is selected from the group consisting of a1) an organic acid having a pKa of below 4.2, selected from the group consisting of
a1a) an aromatic sulfonic acid, anda1b) a singularly or doubly alkoxy-, mercapto- or alkylmercapto-substituted alkanecarboxylic acid having two carbon atoms, a singularly or doubly halogen-, alkoxy-, mercapto- or alkylmercapto-substituted alkanecarboxylic acid, an alkenedicarboxylic acid or an alkanedicarboxylic acid having at least three carbon atoms; a2) a phosphite:and
a4) an acidic phosphorus derivative selected from the group consisting of
a4a) a mono- and di-C1 to C12 alkyl phosphate,a4c) a mono-C1 to C12 alkyl phosphinate, anda4d) an alkyl derivative of a phosphorus-containing diacid, and wherein: a polyisocyanate of the polyisocyanate mixture comprises an isocyanurate, biuret, allophanate, or allophanate with urethane group, the additive does not include a 2-chloroalkanecarboxylic acid or a 3-chloro alkanecarboxylic acid; and R is optionally an aryl group which is substituted in positions 2, 4 and 6 as follows:
position 2: tert-butyl, or tert-amyl,position 4: hydrogen, alkyl, tert-butyl, or tert-amyl, andposition 6: hydrogen, alkyl, tert-butyl, or tert-amyl,with the proviso that at least one of substituents in positions 4 and 6 is not hydrogen.