| abstract |
Medium-density fibre boards, coated on at least one surface thereof, whereby the coating may be produced by applying at least one coating material to the surfaces and hardening the resultant layer(s). At least one of the coating materials contains (A) the aqueous dispersion of a block co-polymer, comprising isocyanate-reactive functional groups obtained by the twin- or multiple-stage controlled radical block co-polymerisation in an aqueous or organic medium, whereby (1) in a first stage (a) at least one olefinic unsaturated monomer and (b) at least one olefinic unsaturated monomer, different from the olefinic unsaturated monomer (a), of general formula (I): R<1>R<2>C=CR<3>R<4> are co-polymerised, (2) in a second stage a further monomer (a) is (co-)polymerised in the presence of the co-polymer from the first stage without addition of radical initiators and (B) a polyisocyanate. |