GB1225250A - - Google Patents

Abstract

1,225,250. Laminates. REICHHOLD CHEMICALS Inc. 5 Jan., 1968 [6 Jan., 1967], No. 56192/67. Heading B5N. [Also in Divisions B2 and B6] A matrix suitable for use in preparing plastics or electrotype printing plates is produced from a blank in the form of a laminate comprising a thermoplastic film 11a supported on a substrate of impressionable fibrous material 12a impregnated with a polymeric thermosetting material adapted to restrict the thermal distortion of the subsequently applied intaglio image in the surface of the film 11a at temperatures above about 250‹ F. A layer of clay-filled phenolic resin 12b or adhesive (20), Fig. 3 (not shown), may be located between the film 11a and the material 12a. The film is not more than 5 mils in thickness and is substantially non-hydroscopic, has an elongation in excess of 100%, and has a smooth exposed low surface tension surface with suitable parting properties for the production of printing plates. The surface adjacent the coating 12b may be corona-treated to increase its adhesion. Suitable materials for the film are stated to be polytetrafluoroethylene, polymonochlorotrifluoroethylene, or polypropylene. The polypropylene may be laminated with a nylon sheet (16), Fig. 2 (not shown), the nylon sheet being located adjacent the substrate to act as a bonding agent. Examples of suitable thermosetting resins are stated to be phenol formaldehyde, melamines, polyesters or epoxy resins. Two layers of fibrous material such as a wood or cotton fibre paper product may be used, the layer adjacent the film 11a containing more thermosetting resin than the other layer. For electroplating, the edges of the imaged surface are water-proofed with a lacquer and silver nitrate is sprayed on the polypropylene image to render it electroconductive. An image adapted to produce a plate having a definition above about 100 lines per inch is moulded on the blank using heat and pressure so that the film softens and a relief surface is impressed into the film and the substrate, Fig. 5 (not shown). As the substrate becomes rigid the depressions therein are irreversibly hardened. In the embodiment of Fig. 4 (not shown), the substrate includes a thick asbestos layer (26), which is not necessarily impregnated with resin.