Flame treatment of polyvinyl fluoride film

Claim 1

A PROCESS FOR RENDERING THE SURFACE OF POLYVINYL FLUORIDE FILM DIRECTLY BONDABLE TO GLASS FIBER-REINFORCED POLYESTER STRUCTURES TO FORM HYDROLYTICALLY STABLE-BOND STRUCTURES WHICH COMPRISES IN COMBINATION THE SEQUENTIAL STEPS OF: (1) BRINGING A SURFACE OF POLYBINYL FLUORIDE FILM CONTINUOUSLY INTO INTIMATE CONTACT WITH A MOVING, RELATIVELY HIGHLY THERMALLY CONDUCTIVE SURFACE MAINTAINED AT A TEMPERATURE EFFECTIVE TO BRING THE FILM PASSING THEREOVER TO A BULK TEMPERATURE WITHIN THE RANGE OF FROM 40*C. TO 135*C.; (2) PASSING SAID FILM WHILE IN CONTACT WITH SAID SURFACE THROUGH THE STABLE, SELF-SUSTAINING FLAME OF A BURNER DISPOSED PARALLEL TO SAID FILM AND TRANSVERSELY OF THE DIRECTION OF TRAVEL THEREOF, SAID BURNER BEING SUPPLIED WITH A GASEOUS MIXTURE CONSISTING ESSENTIALLY OF A HYDROCARBON FUEL, OXYGEN AND NITROGEN, SAID FUEL BEING SELECTED FROM THE GROUP CONSISTING OF PARAFFINIC AND OLEFINIC HYDROCARBONS, THE FUEL EQUIVALENCE RATIO OF SAID GASEOUS MIXTURE RANGING FROM 1.05 TO 1.20, THE OXYGEN RATIO OF SAID GASEOUS MIXTURE RANGING FROM 0.15 TO 0.25, THE DISTANCE FROM THE SURFACE OF THE FILM TO THE DISCHARGE OPENING OF SAID BURNER BEING GREATER THAN THE LENGTH OF THE UNIMPEDED PRIMARY ENVELOPE OF SAID FLAME, SAID THERMALLY CONDUCTIVE SURFACE OPPOSITE THE FLAME BEING MAINTAINED AT SAID TEMPERATURE WITHIN THE RANGE OF FROM 40*C. TO 135*C., THE EXPOSURE OF THE FILM TO THE ACTION OF SAID FLAME BEING FOR A TIME BETWEEN 0.01 SECOND AND 0.5 SECOND; AND (3) MAINTAINING SAID FILM IN CONTACT WITH SAID MOVING, RELATIVELY HIGHLY THERMALLY CONDUCTIVE SURFACE FOR A TIME AFTER PASSAGE OF SAID FILM THROUGH SAID FLAME.