| 摘要 |
1290409 Seaming non-metallic sheet material; laminating OTTO NIELSEN EMBALLAGE AS 24 June 1970 [24 June 1969] 30740/70 Headings B5K and B5N Two sheets at least one of which is a film of EVA-modified polyethylene, i.e. polyethylene containing a small amount, e.g. 2-5%, of ethylene vinyl acetate, are heat sealed together by subjecting the EVA-modified film(s) to a corona discharge in a high tension electric field and heat sealing the sheets by heat and pressure. The sheets may be sealed together either to form a laminate or to form the closure of a filled bag. In one embodiment. Fig. 1, a film 11a is coated with adhesive by a coater 13, dried at a station 14 and laminated to a second film 17a by rollers 16. An EVA-modified film 19a which has been treated with a corona discharge on the side adjacent the film 17a is laminated to the other films by rollers 18, heat being applied by a heater 10. In a second embodiment, Fig. 2 (not shown), a film, e.g. of polyamide, polypropylene, polyvinyl chloride, polyethylene or polystyrene, is extruded through a slit nozzle and an EVA. modified polyethylene film is laminated thereto by rollers. The heat in the extruded film may be used to assist lamination or the film may be cooled and reheated. In a further embodiment, Fig. 3, films or foils from two rolls 31, 33 are bonded by rollers 34 to EVA-modified polyethylene film from a roll 32 which film has been treated on both sides by a corona discharge. Heaters 35 are provided. A tearable weld, e.g. a bag seal, may be formed between the electrically treated side of an EVA-modified polyethylene film and nitrocellulose lacquered cellulose film, unlaequered polyester film, polyvinylidene chloride lacquered polyester film, polyvinylidene chloride lacquered oriented polypropylene film, untreated or electrically treated low density polyethylene film, untreated high density polyethylene film, aluminium foil, hard and smooth paper, polyvinyl chloride or a second electrically treated EVA- modified polyethylene film. A fully effective weld, e.g. to form a laminate, may be formed between the electrically treated side of an EVA-modified polyethylene film and unlacquered cellulose film, polyvinylidene chloride lacquered cellulose film, polyamide film, electrically treated high density polyethylene film or untreated butylene film. |
