CH504025A - Relief printing devices prepared from copolyamides - Google Patents

Abstract

Manufacture of printing plates and devices from synthetic copolyamides prepared from compositions comprising 90-30% wt. linear polyamide (I), 10-70% wt. other monomers (II) containing at least two polymerisable double bonds, in conjunction with 1-50% (pref. 5-40% wt. of total monomers) N-methylolacrylamide and/or N-methylolmethacrylamide, and in the presence of 0.01-10% wt. (pref. 0.01-3% wt.) on total mixture of suitable photo-initiators (III) and/or thermal polymerisation inhibitors (IV). Rapid process needing relatively short exposures which produces a printing plate, having very sharp outlines, in relief, which can be associated with flexible or rigid supports, and which has a high resistance to abrasion and wear. Composition is not subject to undesirable cross-linking reactions during the preparation of the plates or layers from the copolyamide composition and before exposure to light. Achieved by exposing layer of above copolyamide (prepared by usual extrusion, casting or similar techniques) in contact with negative to suitable light source as in prior art, followed by removal of unexposed material by washing with benzene-methanol-water (2:7:1) mixture. The copolyamides used are soluble in the usual mixtures of solvents and are generally prepared by anionic polymerisation starting with any of the well known monomer. The well known photo-initiators (III) decompose into radicals on exposure to light and thereby induce the cross-linking polymerisation reactions. The inhibitors.