Method of and apparatus for flame spraying polyethylene and other plastics

Claim 1

IN A PROCESS OF SPRAYING FROM A GUN UPON A FOUNDATION A THERMOPLATIC MATERIAL HAVING A SOFTENING TEMPERATURE AT LEAST AS MUCH AS 50*F. BELOW ITS DECOMPOSITION TEMPERATURE, SAID PROCESS COMPRISING BURNING A PREMIXED FUEL AND OXIDIZING GAS DIRECTED AT SAID FOUNDATION AND GIVING SUBSTANTIALLY AS HOT A FLAME AS A PREMIXED ONE OF OXY-ACETYLENE, AND EJECTING SAID THERMOPLASTIC MATERIAL ALSO TOWARD SAID FOUNDATION BUT AT A LOCATION SPACED FROM THE BURNING FUEL, THE COMBINATION THEREWITH OF THE IMPROVEMENT FOR REDUCING THE DANGER OF OVERHEATING SAID THERMOPLASTIC, SAID IMPROVEMENT COMPRISING EJECTING A STREAM OF NON-COMBUSITBLE COOLING GAS BETWEEN THE STREAM OF THERMOPLASTIC MATERIAL AND THE BURNING FUEL STREAM UNTIL COMBUSTION OF THE FUEL IS SUBSTANTIALLY COMPLETE, SAID COOLING GAS COMPLETELY SEPARATING THE EJECTED STREAM OF THERMOPLASTIC MATERIAL FROM SAID FLAME AND SHIELDING SAID THERMOPLASTIC MATERIAL FROM THE HEAT OF THE BURNING FLAME FOR A SUBSTANTIAL DISTANCE IN THE PORTION OF THE FLIGHT OF THE MATERIALLY DURING WHICH COMBUSTION OF THE FUEL IS LARGELY TAKING PLACE AND THEN MIXING THE MATERIAL STREAM, AND THE PRODUCTS OF COMBUSTION.