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US 4,734,356 AGranted
Positive-working color proofing film and process
AssigneeE. I. Du Pont de Nemours and Company
InventorsRichard D. Bauer, John G. Buzzell, Rusty E. Koenigkramer
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Abstract
Photopolymer positive surprint color proofing film based on epoxy acrylate monomer exhibits low dot gain, low time dependence of toning and good tonal range. Binder can be methylmethacrylate/ethyl acrylate/acrylic acid copolymer, preferably crosslinked with zinc ions and plasticized with a second acrylate monomer and a mixture of triacetin and trimethylol propane.
Claims11
An improved positive surprint process of making a multi-color proof by the steps:
- (a) laminating to paper the tacky photopolymerizable layer of a film composed of that layer and a transparent support layer:
- (b) imagewise exposing the photopolymerizable layer to UV light through a color-separation halftone-positive transparency to cause polymerization and reduce tack in the exposed areas so that toner particles will not adhere to those areas;
- (c) removing the support layer without disturbing the photopolymer layer;
- (d) applying process-color toner to the photopolymer layer whereby the toner adheres to the unexposed areas only;
- (e) removing non-adhered toner particles to leave a positive image;
- and
- (f) laminating to the toned photopolymer layer the photopolymerizable layer of another piece of the film and repeating steps (b)-(e) using a different color separation transparency and corresponding color toner;
- the improvement characterized in that the photopolymerizable layer consists essentially of a monomer which is a diacrylate or dimethacrylate ester of bisphenol A/epichlorohydrin epoxy resin, a compatible polymeric binder, and a photopolymerization initiator.
5 more elements
Dependencies are inferred from the claim text.