| 摘要 |
The plate has a substrate (I) and a photopolymerisable light-sensitive coat (II) covered by a silicone rubber coat (III). (II) contains a triarylmethane print-out dyestuff (IV), an organic amine (V) and a (substd.) fluorenone (VI). (II) pref. contains 0.01-10 (wt.)% (IV), 0.1-40% (V) and 0.01-30% (VI). It also contains a monomer or oligomer with polymerisable ethylenically unsatd. gp(s)., a photopolymerisation initiator and a film-forming polymeric binder. The plate also has a primer coat between (I) and (II). (III) is obtd. by curing a mixt. of 100 pts. organopolysiloxane with alkenyl gps. attached directly to Si atoms, 0.1-1000 pts. organo-H-polysiloxane with SiH gps. and 0.00001-10 pts. addn. catalyst. USE/ADVANTAGE - Images with high contrast are obtd. and the exposure is practicable (ca. 1/2-2 times the usual exposure). In an example, a primed Al plate was given a 5 g/sq.m (dry) coating with a soln. of 1.5 pts. `Sanprene IB1700D' (RTM), 0.5 pt. `A-1000' (RTM; polyethylene glycol diacrylate), 1.0 pt. adduct of xylylene diamine/glycidyl methacrylate in 1:4 molar ratio, 0.35 pt. ethyl Michler's ketone, 0.10 pt. 2,4-diethylthioxanthone, 0.01 pt. naphthalene sulphonate of Victoria Pure Blue BOH, 0.03 pt. `Defenser MCF 323' (RTM; fluorinated nonionic surfactant, 30% soln. in MIBK), 25 pts. propylene glycol methyl ether and (A) 0.10 pt. fluorenone, (b) no additive, (C) 0.10 pt. anthrone, and samples (B, C) were controls. It was then given a 2 g/sq.m (dry) silicone rubber coat. The plate was exposed through a positive film (20% half-tone dots; density 200 lines/inch) with 30 or 15 counts. The Macbeth density with 0% exposure with standardised light was (A) 0.30, (B) 0.35, (C) 0.40 with 30 counts and (A) 0.30, (B) 0.41, (C) 0.46 with 15 counts; and the half tone dot rating with a plate scanner (A,B,C) 20% with 30 counts and (A) 20, (B, C) 10% with 15 counts. (A) had high print-out properties and was pref. used with a plate scanner |
