Polyisocyanates that are Blocked by Mixing with ?-Caprolactam and DIPA or 1,2,4-Triazole, Their Production and Use Thereof

摘要

It has been found that a special combination of epsilon-caprolactam blocking agent, diisopropylamine, and 1,2,4-triazole for preparation of stoving lacquers leads to special effects, i.e. deep drawability at room temperature and ripping strength (sic) of the coating obtained. A blocked polyisocyanate mixture contains: (A1) 40-70 equivalents % of a predominantly linear NCO prepolymer of NCO content 5.0-10.0 wt.%, (A2) 30-60 equivalents % of an aliphatic polyisocyante paint, (B1), 30-60 equivalents % of an epsilon-caprolactam, and (B2) 40-70 equivalents % of a diisopropylamine or 1,2,4-triazole as blocking agent, where the amount of the (A1) and (A2) components adds up to 100-110 equivalents %. An Independent claim is included for preparation of the blocked isocyanate mixture by first preparation of (A1), where the diisocyanate is at room temperature and the OH component, i.e. polyester, polyether, di- and triol are added with stirring, and on heating to 100-110 deg C the excess NCO groups react with the OH component, and when the calculated NCO content is attained or slightly exceeded the reaction is stopped, the NCO-prepolymer prepared is diluted with solvent and reacted with the lacquer polyisocyanate (A2), so that (sic) the to tal of the NCO components (A1) and (A2) is used for partial blocking with epsilon-caprolactam (B1) at 100-110 deg C, up to the calculated NCO content, and finally the remaining NCO groups are reacted either with 1,2,4-triazole or with diisopropylamine.