The present invention relates to a blocked polyisocyanate containing: A1) 40 to 70 equivalent % of a predominantly linear NCO prepolymer having an NCO content of 5.0 to 10.0 wt. %, A2) 30 to 60 equivalent % of an aliphatic lacquer polyisocyanate, B1) 30 to 60 equivalent % of epsilon-caprolactam and B2) 40 to 70 equivalent % of diisopropylamine or 1,2,4-triazole as blocking agents, wherein the equivalent percents of isocyanate components A1) and A2) add up to 100 %, and the equivalent percents of blocking agents B1) and B2) add up to 100 to 110%, based on the equivalents of component A). The present invention also relates to a process for preparing these blocked polyisocyanates to coating compositions containing these blocked polyisocyanates and to metal substrates coated with these coating compositions.