| 摘要 |
Photopolymerizable compositions comprised of (I) novel polymers which are substantially comprised of the reaction products of (A) organic polyisocyanates and (B) organic compounds containing at least about two active hydrogen atoms per molecule, said polymers having been end-capped by reaction with (C) organic compounds containing exactly one active hydrogen atoms and said end-capped polymers having viscosities of from about 5 to about 70 stokes when measured as a 30% solution in a mixture of approximately equal parts of xylol, methyl ethyl ketone and ethylene glycol monomethyl ether, at 25 DEG C., (II) addition polymerization initiators activatable by actinic light, (III) addition polymerizable ethylenically unsaturated components capable of forming polymers by photoinitiated polymerization in the presence of the initiators, and (IV) a natural or synthetic rubber. The unsaturated components may be integral parts of the polymer's structure, or they may be separate compounds admixed with the polymers and initiators. Relief images, especially useful for printing, are prepared by exposure of a mass of the composition to a light source through, e.g., a transparency which has relatively opaque and relatively translucent areas, and subsequent development of the image by application of a developer composition.
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