| 摘要 |
<p>Direct reproductions which are stable in the colourless as well as in the coloured zones are produced, without further development, by first exposing a material coated with a polychromatic compsn. and placed under a transparent original to UV radiation, usually for 1-10 (pref. 2-6) min., the exposure being combined with heating at 40-140 (70-100) degrees C. The original is then removed and the material is exposed again to UV radiation, usually for a few seconds - 1 minute. The photochromatic compsn. contains a spiropyran of formula (I) or (I) where X is S or C(CH3)2; Y is S or O; R1 is H, OH, Cl, Br, NO2, OCH3, OC2H5, COC6H5, COCH3; R2 is H, OH, Cl, Br, NO2, OCH3, OC2H5, CH2Cl, CH2Br, CH2OR, CH2SR, CH2NR2 where R is alkyl; R3 is H, (thio)alkyl, phenyl, alkoxy, phenoxy, aryloxy, thioaryl; R4 is alkyl, phenyl, benzyl, allyl, phenethyl; R5 is OCH3, SCH3, Cl, Br; R6, R7 R8 and R9, identical or different, are H, alkyl, phenyl, aryl, (CH2)n where n is 5-10, placed on one C atom or joining two adjacent C atoms. The compsn. also contains PVC or a vinyl copolymer contg. 50% pref. 80-92% PVC.</p> |
