Process for the preparation of low-viscosity, water-dilutable urethane (meth)acrylates

摘要

The present invention relates to a process for the preparation of highly reactive, low-viscosity and water-dilutable polyisocyanate reaction products which contain activated groups which react, by polymerization, with ethylenically unsaturated compounds under the action of actinic radiation. The present invention furthermore relates to a process for the preparation of such products and their use.

主权项

1. A process for preparing a low-viscosity, water-dilutable polyurethane (meth)acrylate, comprising reacting components (a), (b), and (d)
(a) at least one organic polyisocyanate with two isocyanate functions; (b) at least one polyoxyalkylene polyol based on a starter molecule which comprises at least three hydroxy functions and is partially reacted by esterification with (meth)acrylic acid such that on average 0.2 to 1.5 hydroxy functions still remain; (d) at least one compound which has at least one group which is reactive towards isocyanate and at least one ionic or potentially ionic function, wherein the at least one group reactive towards isocyanate is an amino group, and wherein component (d) is an addition product of acrylic acid and a diamine, wherein the molar ratio of acrylic acid to diamine is 1:1;to form said low-viscosity, water-dilutable polyurethane (meth)acrylate, wherein, said polyurethane (meth)acrylate contains less than 40 weight % of alkylene oxide units;whereinthe reaction product of components (a), (b), and (d) has an NCO content of less than 0.5 weight %, andsaid polyurethane (meth)acrylate is not prepared from either of
(i) organic polyisocyanates with three or more isocyanate functions, or (ii) polyoxyalkylene polyols which have a maximum of two hydroxy functions but no further groups which can be crosslinked by actinic radiation.