VERFAHREN UND EINRICHTUNG ZUR FLAMMENVERBINDUNG UND DAMIT HERGESTELLTE GEGENSTAENDE

1423371 Laminates; seaming non-metallic sheet material CONSOLIDATED-BATHURST Ltd 10 Jan 1973 [27 Jan 1972] 1315/73 Headings B5N and B5K A surface of a layer of thermoplastic material is bonded to another surface by heating the surface of the thermoplastic material by contact with a flame of velocity above 10,000 feet per minute and temperature above 1000‹ F. to heat it substantially uniformly in a substantially continuous path thereon and pressing the heated surface against the other surface, e.g. by the use of nip rollers. Lamination may be effected using small nip rollers adjacent the flame and large nip rollers spaced from the small nip rollers, the small nip rollers optionally forming an open nip. Two rows of rectangular burners may be provided in staggered overlapping arrangement to provide a uniform temperature line across the width of the material, adjacent burners preferably being staggered at an angle of 55-60 degrees. Alternatively burner means having a circular shaped gaseous discharge opening may be used. The gaseous combustible material may be propane and air, hydrogen and oxygen or air, acetylene and oxygen or air, steam optionally being injected into the flame to adjust to water vapour content. The thermoplastic material which may be in the form of woven tapes may be low or high density polyethylene or polypropylene, polyvinyl chloride, nylon, polyester, polytetra fluoro-ethylene, acrylic, polyurethane, polystyrene or Cellophane (Registered Trade Mark) and the other surface may also be of thermoplastic material or of paper or aluminium foil. The thermoplastic layer may be bonded to itself to produce tubular structures or used in the production of bags. Laminates comprising layers of fibrillated films or other scrim-like materials of polyethylene or polypropylene bonded to layers of paper may be produced. In Fig. 1 continuous webs 10 and 12 of thermoplastic material fed from rolls 14 and 16 are heated by one or more burners 28 and pressed together by nip rollers 22 and 24 of relatively small diameter which may be cooled. In an alternative arrangement a pair of large rollers may be provided spaced from the small rollers, the small rollers optionally spaced apart from each other to provide a nip gap.