| 摘要 |
<p>The process is characterised in that a substrate is coated with a product obtained by reacting A) a prepolymer containing an average of 2 ketoxime-blocked NCO groups and having a mean molecular weight of from 500 to 15,000, based on an aromatic polyisocyanate, with B) a chain extender of the formula… H2N-R'-NH2… in which R' is an aliphatic radical,… in the presence of solvents at temperatures of >50 DEG C and at a ratio between the number of equivalents of blocked NCO groups and NH2 groups of 1.43 to 1.02, with from 40 to 90 % of the available amino groups being reacted, and the reaction is subsequently completed at temperatures of >120 DEG C with crosslinking.</p> |
