Basf Aktiengesellschaft

Klaus-Peter Jaeckel

Horst Koch

Reinhold J Leyrer

Hans Schupp

Albert Elzer

Helmut Bach

A printing cylinder or a sleeve is coated with a continuous photosensitive recording layer by applying a first jointless stratum of a photosensitive recording layer to the printing cylinder or the sleeve, and uniformly preexposing this first stratum to actinic light and thereafter applying one or more further jointless strata of the photosensitive recording layer to this preexposed first stratum.

Coating plate cylinders or sleeves with a continuous photosensitive

Non-tacky, smooth, structureless surfaces of photopolymer relief printing plates for flexographic printing, whose relief layers are prepared in a conventional manner by exposing the photopolymerizable relief-forming layers of flexographic printing plates imagewise to actinic light and washing out the unpolymerized, unexposed areas with a suitable solvent, are produced by a process in which the flexographic printing plates are after-treated with a liquid medium which contains elemental bromine or is capable of forming elemental bromine, and then washed with a neutralization bath, one or more paraffinsulfonates, fatty alcohol ethersulfates or alkyl phosphates or a cationic or anionic surfactant possessing one or more perfluorinated carbon chains being employed in the bromine-containing, liquid medium. The relief printing plates obtained according to the invention are used for flexographic printing.

Production of non-tacky, smooth surfaces of photopolymer relief printing

A curable photosensitive mixture which is suitable as a positive-working recording material contains (a) one or more polymers which have a molecular weight of &gt;500, contain not less than 5% by weight, based on the molecular weight of the polymer, of aromatic and/or heteroaromatic o-nitrocarbinol ester groups and also contain two or more further reactive functional groups which are available for reaction with a thermal crosslinking agent, (b) one or more compounds which effect crosslinking and are capable of reacting with the further reactive functional groups of the polymer (a) under the action of heat, at temperatures substantially above room temperature, and (c) a filler, with or without (d) other conventional additives and/or assistants. The photosensitive mixture is particularly useful as a positive-working recording material for optical information fixing, principally for the production of thermally stable relief images or resist images and, particularly advantageously, of soldering masks.

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Oberkirch, Germany

Klaus-Peter Jaeckel