PHOTOPOLYMERIZABLE PRINTING PLATE FOR MAKING RELIEF PRINTING PLATE THAT PRINTS WITH UV-CURABLE PRINTING INK

摘要

PROBLEM TO BE SOLVED: To obtain a photopolymerizable mixture that exhibits improved swelling resistance to a UV-curable printing ink, a reduced tonal gain and a reduced tendency to react with a polymerizable component in the UV-curable printing ink and attains the highest resolving power of an ordinary flexographic printing plate and to obtain a photopolymerizable printing plate for making a relief printing plate. SOLUTION: An elastic block copolymer used consists of blocks S of styrene, random blocks S/B of styrene and butadiene and blocks S of styrene. The glass transition temperature Tg of the blocks S is higher than 25 deg.C and that of the blocks S/B is <25 deg.C. The relative volume ratio between the blocks S and S/B is so selected that the hard phase S occupies 1-40 vol.% of the entire block copolymer and the volume fraction of butadiene is <50 wt.%.