Polycyclic polycarbonate (or thiol analog) oligomers are prepared from a mixture of at least one bishaloformate with at least one tetraphenol, or thio analogs thereof. Such mixture may also contain at least one dihydroxy or dimercapto compound. The oligomers are formed by the reaction of such mixtures with alkali metal hydroxides and various amines. The polycyclic oligomer mixtures may be converted to crosslinked polycarbonates or their thiol analogs.

This invention relates to a one- or two-component diazo-type material with improved light stability and duplication capabilities. This is accomplished by using compounds of the general formula ##STR1## wherein R.sub.1, R.sub.2, R.sub.3, R.sub.4 being the same or different, represent hydrogen, alkyl with 1 to 5 carbon atoms, R.sub.1 and R.sub.2 and/or R.sub.3 and R.sub.4 represent the alkyl groups necessary for completion of a 5- or 6-membered heterocyclic ring, wherein the ring may comprise a further hetero atom, such as N, O or S; R.sub.5, R.sub.6 being the same or different, represent hydrogen, aryl, alkyl with 1 to 4 carbon atoms; Y represents --S--, --SO--, --SO.sub.2 --; and n is 0, 1, 2, 3, which are added to the material as fading inhibitors. These compounds can be easily synthesized and are compatible with the system, having an absorption maximum below 380 nm and reduced fogging tendency. They may also be employed in the form of their hydro salts.

Polycyclic polycarbonate (or thiol analog) oligomers are prepared from a mixture of at least one bishaloformate with at least one tetraphenol, or thio analogs thereof. Such mixture may also contain at least one dihydroxy or dimercapto compound. The oligomers are formed by the reaction of such mixtures with alkali metal hydroxides and various amines. The polycyclic oligomer mixtures may be converted to crosslinked polycarbonates or their thiol analogs.