GB1300177A - Improvements in and relating to the production of laminates, especially flexible laminate - Google Patents

Abstract

1300177 Coating KALLE AG 7 Aug 1970 [8 Aug 1969] 38209/70 Heading B2E Synthetic films, e.g. of polyethylene, polypropylene, polyvinyl chloride, polyamide, polyethylene terephthalate, or regenerated celluose, are coated with a solution or a dispersion of a prepolymer and then sprayed with an atomized liquid hardening agent and heated at 50-150‹C to harden the polymer. The solution or dispersion preferably contains 5 to 50% of prepolymer solids which may be a prepolymer containing an OH group, for example polyvinyl alcohol, partially saponified copolymers of vinyl chloride and vinyl acetate, partially saponified copolymers of ethylene and vinyl acetate and partially saponified polyvinyl acetate or linear or branched polyethers or polyesters; preipolymers containing NCO groups. for example prepared by the reaction of polyesters or polyethers with polyisocyanates in excess; or polymers containing nitrogen such as polyethylene imine or copolymers of ethylene imine and polyols especially copolymers of ethylene imine and urea. Suitable hardeners are aqueous solutions of formaldehyde which may be acidified by means of formic or acetic acid or solutions of polyisocyanates or triisocyanates, for example toluylene diisocyanate, hexamethylene diisocyanate and triphenyl-4,4', 4"-triisocyanate and particularly the triisocyanate formed from trimethyl propane and an excess of toluylene diisocyanate. The solution or dispersion of the prepolymer may be applied by rollers or airbrushes or kiss coating. The dried coating may be peeled from the support and transferred.