Photopolymerisable compsns. for printing plates etc. - contain polymerisable monomer, polymeric binder, photoinitiator and etherified thio-anthraquinone cpd.

摘要

The compsns. contain (a) >=1 cpd. of low mol. wt. and contg. >=1 unsatd. photopolymerisable double bond; (b) >=1 compatible organic polymeric binder; (c) a photo-initiator; and (d) 0.001-0.1 wt. % of an etherified thioanthraquinone cpd. of formula (I):- in which R is 1-12C alkyl, 1-8C alkyl substd. by an opt. etherified and/or esterified OH gp. and/or an alkoxycarbonyl gp., or an opt. substd. phenyl gp. Pref. cpds. (I) are propyl-, n-butyl-, and isobutylthioanthraquinones, and esp. 2-butylthio-2-anthraquinone (II). Presence of the (I) in known photopolymerisable compsns. reduces undesired polymerisation of the compsn. in the shadow of fine opaque image elements during exposure in contact with a negative, thus giving improved image clarity. The presence of the (I) does not reduce the light sensitivity or exposure latitude of the material.