Patent ID: 7419765

Claim:
A process for the production of flexographic printing plates by means of direct laser engraving by engraving a relief in a laser-engravable flexographic printing element using a laser apparatus which comprises at least one unit for holding a cylindrical substrate for flexographic printing elements in which the cylindrical substrate can be rotatably mounted, one drive unit for rotating the cylinder, one laser head which emits at least one laser beam, the laser head and the holding apparatus with the cylindrical substrate being mounted so as to be displaceable coaxially relative to one another, and one suction apparatus, and in which a laser-engravable flexographic printing element at least comprising a dimensionally stable substrate and an elastomeric, relief-forming layer having a thickness of at least 0.2 mm, comprising at least one elastomeric binder, is used as starting material, the process comprising at least the following steps: (a) application of a laser-engravable flexographic printing element to the cylindrical substrate and mounting of the cylindrical substrate in the holding unit, (b) rotation of the cylindrical substrate, (c) engraving of a printing relief in relief-forming layer with the aid of the at least one laser beam, the depth of the relief elements to be engraved by the laser being at least 0.03 mm, wherein the particulate and gaseous degradation products formed in the course of the engraving are taken up by means of the suction apparatus, and the waste gas stream laden with the degradation products is purified by means of a system comprising at least two different filter units, particulate degradation products being deposited in a first filter unit in the presence of a finely divided, nontacky solid by means of a solids filter and remaining gaseous degradation products then being removed oxidatively by means of catalytic oxidation from the waste gas stream in a second filter unit, wherein the aspirated gas volume is at least 0,1 m 3 per g of degraded material and the second filter unit comprises a buffer unit upstream of the oxidative purification stage, in which the gaseous degradation products in the waste gas are completely or partly collected and are released in a defined concentration to the oxidative purification stage.