Production of relief plates and printing plates by a positive-working method

US4816379A · kind A · utility

Assignee

• BASF SE

Inventors

• Bernd Bronstert · Otterstadt, DE
• Gerhard Hoffmann · Otterstadt, DE
• John Lynch

Key dates

• Filing date: Apr 22, 1985
• Grant date: Mar 28, 1989
• Expiry date: Apr 22, 2005

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10S430/123
• WIPO field: Optics
• WIPO sector: Instruments

Abstract

Relief plates and printing plates are produced by a positive-working process, using a photopolymerizable layer which contains one or more photopolymerizable, olefinically unsaturated compounds, one or more photoinitiators which can be activated by UV light, and a combination of a phenothiazinium, phenoxazinium, phenazinium or acridinium dye with a mild reducing agent which, on exposure to visible light, is capable of reducing the dye in the excited electronic state. The photopolymerizable layer is exposed imagewise to light having a wavelength longer than 450 nm, and simultaneously or subsequently exposed uniformly to light having a wavelength of from 300 to 420 nm, after which the unpolymerized areas of the layer are removed.