Laminates for the manufacture of relief printing plates

Claim 1

A laminate for the manufacture of relief plates for flexographic printing, consisting essentially of: A. a base (U) which is from 0.5 to 6 mm thick and consists of an elastomeric material which has a modulus of elasticity of from 10 to 200 kg/cm 2 , B. an intermediate layer (Z) which is firmly bonded to the base, is from 5 to 500μ thick, has a modulus of elasticity of from 1 × 10 3 to 2.1 × 10 6 kg/cm 2 , is insoluble in the developer used, in the production of the relief, for washing out the unexposed areas of the layer P, in the constituents of the layer P used to produce the relief and in the printing ink solvents, and is impermeable or only very slightly permeable to these solvents, C. a photo-crosslinkable layer (P) which is firmly bonded to the intermediate layer Z, and is from 200 to 3,000μ thick and consists essentially of a photo-crosslinkable mixture of P1. from 50 to 99 percent by weight of an elastomer, and P2. from 1 to 50 percent by weight of a photopolymerizable olefinically unsaturated monomer which is substantially compatible with the elastomer, with the proviso that in the unexposed state the layer P is soluble in a developer solution in which said layer P which has been exposed and photo-crosslinked (P1) is no longer soluble, and that the layer P' has, in the exposed and photo-crosslinked state, a modulus of elasticity of from 30 to 2,000 kg/cm 2 which is equal to or greater than that of the layer U, and D. the neutral surface of the laminated layers u, x, and of the layer P in the photo-crosslinked state (layer P') after exposure of the entire surface of layer P lying in the intermediate layer Z or at a distance from the intermediate layer Z which does not exceed 10% of the thickness of the layer U or P.