| abstract |
Compounds of the formula I <IMAGE> in which R<1> is an alkylene-, cycloalkylene-, alkenylene-, alkynylene- or arylenebisalkyl group in which one or more aliphatic CH2 groups may be replaced by oxygen or sulphur atoms, R<2> is an alkyl, alkenyl, alkynyl, cycloalkyl, alkoxyalkyl, aryl, aralkyl or aryloxyalkyl radical, R<3> is an alkyl or aryl radical, X is one of the groups -CO-, -OCO- or -NHCO-, and n is an integer greater than 1, in particular from 3 to 50, are acid-cleavable and, in combination with photolytic acid donors and alkali-soluble binders, are constituents of positive-working mixtures which are used, in particular, in recording materials for UV radiation and high-energy radiation. The materials are distinguished by high resolution together with high image contrast. |