GB999550A - Flame treatment of polyvinyl fluoride film - Google Patents

Abstract

999,550. Flame treatment of polyvinyl fluoride film; laminates and laminating. E. I. DU PONT DE NEMOURS & CO. July 17, 1963 [July 18, 1962], No. 28354/63. Drawings to Specification. Headings B5B and B5N. Polyvinyl fluoride film is rendered adherent to other materials by bringing a surface of the film into intimate contact with a moving, relatively highly thermally conductive solid surface maintained at a temperature of 70‹ to 135‹ C. and passing the film while in contact with this surface through the secondary or outer envelope or mantle of a steady flame of a burner disposed parallel to the film and transversely to its direction of travel, the flame being free from yellow luminosity. The burner is supplied with a gaseous mixture of a paraffinic or olefinic hydrocarbon fuel (preferably propane), oxygen and nitrogen, the proportion of fuel in the mixture being 0À85 to 1À05 of that theoretically corresponding to complete combustion of the mixture, and the proportion of oxygen in the total amount of non-fuel components in the mixture (chiefly oxygen and nitrogen) being 0À21 to 0À35. The distance from the free surface of the film to the discharge opening or openings of the burner is less than the length of the unimpeded primary envelope or inner mantel or cone of the flame but not less than the distance below which the velocity of the burning gases escaping from the immediate vicnity of the discharge opening or openings exceeds the burning velocity of the flame. The film is exposed to the flame for a time between 0À001 second and 0À5 second and is maintained in contact with the moving thermally conductive surface for a time after it has left the flame, whereby the average contact angle (for water) of the treated surface of the film is reduced to a value below about 40 degrees. The film may have been biaxially oriented before being treated as above. Polyvinyl fluoride films are normally extremely difficult to bond to metallic and non-metallic substrates to form laminar structures. Polyvinyl fluoride films treated according to the invention can be satisfactorily used for this purpose. In examples, aluminium panels passivated with an amorphous oxide-chromate coating are coated with a solution of an ammoniated acrylic interpolymer of n-butylmethacrylate and glycidyl methacrylate in a mixture of isopropanol, xylene and toluene and, after being heated to 190‹ to 220‹ C., the coated panels are united with P.V.F. film treated according to the invention and passed through the nip of a pair of rubber-covered rolls at a pressure of about 85-90 p.s.i.