Light sensitive mixt. contg. polyurethane resin - from isocyanate prepolymer and poly:ol and diazonium salt polycondensate for negative working printing plate

摘要

Polyurethane resin (I) used as binder in a light-sensitive mixt., contg. a light-sensitive diazonium salt polycondensation prod. (II), is a reaction prod. of a (branched) polyurethane prepolymer (III) with terminal free NCO gps. and a cpd. (IV) with min. 3 OH gps. in the mol. Pref. (I) has mol.wt. of under 1500 and is the reaction prod. of (III) and 1 mole (IV) per equiv. NCO gp. in (III). (IV) is an at least trihydric aliphatic alcohol. The mixt. contains 0.5-4 (wt.) pts. (I)/pt.(II). Compsn. is negative working and is useful for making printing plates. It can be developed more easily and reliably than the usual mixts.