Method and apparatus employing radio frequency electric energy for heat sealing of laminated packaging materials, particularly aseptic packaging materials, that include facing contiguous layers of thermoplastic material, including first and second seal jaws having respective working surfaces....http://www.google.com.au/patents/US5736719?utm_source=gb-gplus-sharePatent US5736719 - Method and apparatus for heat sealing of packaging materials employing RF electric energy 
