| 摘要 |
1,204,506. Seaming non-metallic sheet material; laminating. W. C. HELLER. 15 Aug., 1967 [15 Aug., 1966], No. 37462/67. Headings B5K and B5N. Predetermined interfacial areas of adjacent heat sealable surfaces of a plurality of sheets are joined by applying a susceptor material comprising electrically non-conductive oxide particles to at least one of the sheets at a location within each of the predetermined areas to be joined but spaced from the adjacent surfaces to be sealed and thereafter inducing heat in the susceptor material to raise the temperature of the predetermined areas sufficiently to seal the adjoining surfaces of the sheets within these areas. The invention is applicable to the sealing or laminating of sheets forming bags, carton liners, bag closures, carton overwraps and coated folding cartons. In one embodiment, Figs. 1 (not shown), and 2, a multi-layered sheet containing susceptor material is prepared by magnetic hysteresis heating by feeding a paperboard ply (32), Fig. 1, and a thermoplastic film (36) with a perforated susceptor material (34), e.g. electrically non-conductive ferromagnetic oxide particles in a polyethylene or nylon carrier, sandwiched therebetween through a coil (41) and then between pressure rolls (33). This material 32a, 34a, 36a, Fig. 6, is fed with a paperboard ply 31 facing the thermoplastic layer 36a through a coil 41a and then between pressure rolls 46. The susceptor 34, 34a and the thermoplastic film 36, 36a need not be provided in continuous layer but may be arranged in an intermittent pattern according to the desired shape of the bond. The embodiment of Figs. 1 and 2 may be modified to be applied to an intermittent, instead of a continuous, process. In another embodiment, Fig. 8, heat sealing is avoided between two layers of a triple-folded assembly of paper-board 71 coated on both sides with polyethylene 73 and accomplished between other layers. The folded layers with a susceptor material 74 positioned at the inner fold are held in place by a coil 76. Pressure is applied at 77. The material 74 may be prepared by milling iron oxide particles into nylon which is not readily heat sealable to polyethylene. After sealing, the material 74 may be removed for re-use. This embodiment is applicable to sealing milk cartons. In Fig. 9, two plastics films 83 are heat sealed to a wall 82 of a heavier gauge plastics film bag at areas 85 using susceptor layers 87. In Fig. 10, a non-sealing non-susoeptor layer 93 is placed in a fold of a heat sealable material 91. Upon heating the susceptors 87a, heat seals 85a are formed. Instead of using magnetic hysteresis heating, heat may be induced in the susceptor by an ultrasonic energy beam, X-rays, a laser beam, an ion beam, an electron beam or nuclear radiation. |
