| 摘要 |
989,870. Seaming non-metallic sheet material; laminates. L. J. VILUTIS, and M. J. VILUTIS, [trading as VILUTIS & CO.]. Dec. 23, 1963 [Dec. 31, 1962 (3)], No. 50635/63. Headings B5K and B5N. Edge portions 10, 11 of two multilayer thermoplastic films 12, 13 are bonded together by inserting the one edge portion 10 between the layers 15, 17 of the other edge portion and applying energy in some suitable form to bond the interleaved surfaces together. As shown, the edge portions may constitute the outer edges of a single sheet of multi-layer film in which case bonding produces a tubular article having a multilayer wall. The layers of the thermoplastic film may have the same or differing dielectric loss factors. Where at least one of the layers has a high dielectric loss factor dielectric heating may be employed for the bonding of this layer and the heating effect may be sufficient also to cause bonding of an adjacent layer having a low loss factor. Pressure is usually employed to exclude trapped air from the seam area and to ensure intimate connection at the bond. A layer of printing may lie between the layers of the thermoplastic film material. Ultrasonic vibrations may be employed to provide the heating effect necessary for seaming. Materials referred to as having a high dielectric loss factor include the normally crystalline copolymers of vinylidene chloride and vinyl chloride, polyvinyl chloride, polyvinyl acetate, cellulose acetate, cellulose acetate butyrate, rubber hydrochloride, and polyamide. Materials having a low dielectric loss factor include polyethylene, polystyrene and polytetrafluoroethylene. Apparatus is described (Fig. 5, not shown) in which a single sheet of two-ply material is fed continuously to means which fold the sheet, interleave the edges and seal the interleaved portion by means of dielectric heating to form a continuous tubular product. |
