Preparation of recording layers and their use for the production of flexographic printing plates

摘要

A flexographic printing plate which is resistant to ozone cracking and where the flexible recording layer has an anisotropy factor AF of <1.5 is produced from a photosensitive mixture consisting of (A) one or more elastomeric binders, (B) a mixture of (B1) from 5 to 20% by weight of one or more photopolymerizable organic compounds which are compatible with (A) and contain two or more olefinic double bonds and (B2) from 1 to 15% by weight of one or more monoolefinically unsaturated organic compounds which are compatible with (A) and whose homopolymer has a glass transition temperature which is below room temperature, (C) from 0.1 to 10% by weight of one or more photoinitiators and (D) from 0 to 27% by weight of conventional assistants and additives, the anisotropy factor AF of the flexible recording layer being defined as the ratio of the moduli of elasticity at 100% elongation of strips measuring 2x15 cm which have been punched from the flexible recording layer during production of the raw plate, on the one hand along the flow direction of the photosensitive mixture used and on the other hand crosswise to the said direction and have then been exposed uniformly.