Thermographic material with photocured top coat - contains poly:unsatd. heterocyclic cpd., pref. modified tris:hydroxy-alkyl isocyanurate (meth)acrylate

摘要

Thermographic material has a substrate with a heat-sensitive, colour-developing coat and a top coat of a resin compsn. cured by actinic radiation, which contains a polyfunctional unsatd. cpd. (I) with a 6-membered heterocycle contg. an N or O atom and mol.wt. 480-3000, which can be polymerised by free radicals. (I) pref. contains at least 2 (meth)acryloyl gps. and pref. consists of (i) an alkylene oxide, epsilon-caprolactone, epihalohydrin, polycarboxylic acid or anhydride and/or polyisocyanate and (ii) tris(hydroxyalkyl) isocyanurate, i.e. modified tris(hydroxyalkyl) isocyanurate (meth)acrylate. The top coat pref. also contains a pre-polymer (II), other than (I), which is cured by actinic radiation. (II) is a cpd. with at least 3 (meth)acryloyl gps., of formula (IIA) (where n = 0-4; at least 3 X gps. = CH2=CR1-COO-R2-; R1 = H or Me; R2 = a single bond, 1-8 C alkylene or polyoxyalkylene with a 1-8 C alkylene gp.; the remaining X = 1-8 C alkyl, OH, NH2, alkylene, -(OR3)m-H or -(OR3)m-OH; R3 = 1-8 C alkylene; m = a positive integer). The top coat may also contain a reactive diluent (III) and opt. a cpd. (IV) with no unsatd. bond cured by actinic radiation. The compsn. contains 50-95 (wt.)% (I)+(II), 10-50% (III) and 5-35% (IV) and the (I)/(II) ratio is 60/40 to 20/80. The substrate consists of a synthetic resin. USE/ADVANTAGE - The top coat improves the surface glass and suitability for the thermal head.