Patent GB-1371019-A (GB)
Title: Medium for heat bonding
IPC: C09J7/21
Filed: 1973-08-02
Abstract: 1371019 Seaming non-metallic sheet material GUTERMANN & CO 2 Aug 1973 [2 Aug 1972] 36697/73 Heading B5K [Also in Division B2] A medium for heat bonding two sheet material surfaces comprises a carrier sheet 3 one side of which carries, directly or indirectly, layers of a heat bonding substance 5 and of a pressure sensitive adhesive 4, such layers being arranged so that they both present exposed surfaces in a plane substantially parallel to the sheet 3, the layer 5 being readily separable from the sheet 3 after the layer 5 has been adhered to a surface of material. The term "heat bonding substance" denotes a substance capable of effecting bonding of sheet materials under the action of heat. Suitable substances are polyamides, polyamide copolymers, polyurethanes and polyacrylates. In one embodiment, Fig. 1, the joining medium comprises a paper carrier sheet 3 having a rough surface to which a pressure sensitive adhesive 4 has been applied, a heat bonding film 5 being applied to the adhesive 4. The adhesive 4 has greater affinity for the sheet 3 than for a fabric 1 which is to be hemmed. The medium is laid on the fabric 1 at a distance from the cut edge 2 thereof and slight pressure is applied to adhere the medium to the fabric. The medium is ironed to cause the film 5 to melt and partly penetrate into the fabric 1. The sheet 3, together with the adhesive 4, is pulled off of the fabric 1 to leave the film 5 thereon. The fabric edge is folded over the film 5 which is then re-melted by ironing to effect bonding, Fig. 2 (not shown). Suitable constructions of the medium include (a) a strip-like carrier sheet to which the adhesive is applied, the bonding film of smaller width than the adhesive being applied to the adhesive so that the adhesive projects at the edges thereof, Fig. 3 (not shown); (b) the bonding film of zig-zag shape applied to the adhesive, Fig. 4 (not shown); (c) the bonding film being of the same width as the carrier strip but having diamond-shaped cut-outs through which the adhesive is exposed, Fig. 5 (not shown); (d) the carrier sheet having an adhesive layer thereon and the heat bonding substance being in the form of irregular non-woven fibres through which the adhesive is exposed, Fig. 6 (not shown); and (e) the heat bonding substance 55 being disposed on the adhesive 54 is regular portions in columns spaced apart by a short distance, Fig. 7, perforations 56 being provided between the columns. In another embodiment, Fig. 8, the joining medium comprises a coated or impregnated paper carrier 63 having thereon two strips of a pressure sensitive adhesive 64 and one strip of a hot melt adhesive 65. The adhesive 64 has greater affinity for a fabric 61 to be hemmed than for the sheet 63. The medium is adhered to the fabric 61 and ironed thereon. The sheet 63 only is removed leaving the adhesives 64, 65 on the fabric and the hem is subsequently formed. In a modification, Fig. 10, a silicone paper carrier 73 has adhesive dots 74 and bonding dots 75 arranged in a uniform grid pattern thereon. Perforations may be provided for separation into narrower strips. The heat bonding substance may be in the form of layers of particles bonded or sintered together. In modifications, ironing is replaced by another welding method, e.g. contact, impulse, high frequency or ultrasonic welding. The exposed surface of the pressure sensitive adhesive may be covered by a readily removable protective sheet, e.g. this may be provided by the reverse side of the carrier sheet, coated with a silicone release material, when this sheet is rolled up.