Abstract: Photocured layers possessing a defined controllable hardness are produced by exposing a layer of a photopolymerizable or photocrosslinkable mixture, which contains a partially crystalline polymeric binder possessing olefinic double bonds capable of undergoing polymerization, to actinic light, by a method in which the photocurable layer, prior to exposure to actinic light, is subjected to a heat treatment in which the partially crystalline parts of the polymeric binder are partially or completely fused.

Abstract: A photopolymerizable recording material for the production of relief plates comprises a photopolymerizable layer which can be developed in an alcoholic solution and contains a mixture of a photoinitiator, a photopolymerizable monomer and a linear, high molecular weight polyurethane which possesses activated double bonds in side branches, and is prepared using a polyether-diol from the group comprising the polyethylene glycols, propylene glycols and ethylene glycol/propylene glycol co-condensates.

Abstract: A photosensitive multi-layer material comprising a base, which may or may not be provided with an adhesion-promoting layer, and a photopolymerizable layer, consisting of a mixture of a photoinitiator, a binder and a photopolymerizable monomer, possesses, between the base and the photopolymerizable layer, an adhesive layer of a hardened mixture of a binder and an etherified melamine-formaldehyde condensate, hardenable at 60.degree.-120.degree. C.

Abstract: A multi-layer element for the production of printing plates and relief plates which is based on an elastomeric polymer binder and is firmly anchored to a polyester base by means of an adhesive layer. The adhesive layer consists of a thermally hardened mixture which is insoluble in aromatic hydrocarbon solvents or aliphatic halohydrocarbon solvents and contains (c1) from 90 to 40% by weight, based on the sum of (c1) and (c2), of an hydroxyl-containing polyurethane, hydroxyl-containing epoxy, hydroxyl-containing phenoxy resin, polyester-ol or polyether-ol resin which has been hardened and crosslinked with isocyanate, and which has from about 4 to 20% by weight, based on the non-crosslinked and hardenable resin, of free OH groups before hardening and crosslinking with isocyanate, and (c2) from 10 to 60% by weight, based on the sum of (c1) and (c2), of an OH-free polycarbonate which is compatible with the resin (c1) before the latter is hardened and crosslinked.

Abstract: A photopolymerizable recording material for the preparation of relief plates comprises a base and a photopolymerizable layer, which layer contains, as the binder, a substantially linear, high molecular weight, thermoplastic diisocyanate-modified nylon which is solid at room temperature and which possesses quaternary and/or quaternizable nitrogen atoms and also possesses photopolymerizable double bonds in side branches.

Abstract: Photopolymerizable compositions based on an elastomeric styrene-diene block polymer, one or more photopolymerizable olefinically unsaturated monomers and one or more photopolymerization initiators exhibit improved properties if they contain, as an essential constituent, an elastomeric block copolymer of the general structure A-B-C, where A is a thermoplastic, non-elastomeric polymer block based on styrene compounds and having a second order transition point above +25.degree. C., B is an elastomeric polymer block based on butadiene and/or isoprene and having a second order transition point below -20.degree. C. and C is a polymer block, different from B, having a second order transition point of from -30.degree. C. to +15.degree. C., C being either a homopolymer or copolymer block based on butadiene or isoprene or a random copolymer block based on conjugated dienes and styrene compounds.

Abstract: A photopolymerizable composition for the manufacture of printing plates and relief plates, based on a mixture, containing a photoinitiator, of photopolymerizable olefinically unsaturated monomers and a polymeric binder, contains up to 0.1% by weight of an etherified thioanthraquinone for improving the relief image in the production of relief plates.The composition advantageously also contains a small amount of an organic tertiary amine or of an aromatic .alpha.-ketocarboxylic acid or its ester and/or of an inhibitor, e.g. the salt of an organic N-nitrosohydroxylamine.

Abstract: The invention relates to special acetals of benzoin compounds which act as photoinitiators, and to a technically simple manufacturing process involving the reaction of an appropriate .alpha.- or .beta.-hydroxyketone with an .alpha.,.beta.-olefinically unsaturated ether in the presence of an acid catalyst. The acetals are particularly suitable for use as photoinitiators in the preparation of photopolymer printing plates.