GB999821A - Improvements in or relating to methods of bonding - Google Patents

Abstract

999,821. Laminates and laminating; seaming non-metallic sheet material. BRITISH UNITED SHOE MACHINERY CO. Jan. 23, 1962 [Jan. 31, 1961 (2); May 4, 1961], No. 2341/62. Headings B5K and B5N. [Also in Divisions A3 and B2] A method of bonding comprises the steps of directing a stream of heated gas against a surface to be bonded, introducing a heat responsive adhesive composition in powder form into the stream so that it is heated to a tacky condition and is carried on to the surface where it forms a layer of discrete particles adherent to the surface, heating the particulate layer by the stream of gas to fuse the particles to form a substantially continuous layer and pressing a second surface against the continuous layer. A hand-held gun is used comprising a barrel 12 containing electrical heating means 106, a pipe 18, the opening 84 of which is adjacent the barrel orifice 13, a container 16 for powdered adhesive and a device 60 for supplying adhesive to the pipe. In operation, air passes through the barrel, is heated by the heating means therein and emerges as a stream of heated air from the orifice 13; air passes through the pipe and issues as a stream from orifice 84 and on actuation of a trigger 20 the device 60 operates whereby adhesive is supplied to the pipe and issues therefrom as a stream of particles which is directed into the stream of heated gas issuing from the barrel. The adhesive may be a mixture of two different heat fusible resins, one of high melting point and the other preferably thermo-setting, of low-melting point. The resins may be in the form of separate particles or the low-melting resin may be coated on to the high-melting resin. High melting point resins specified are linear polyesters or copolyesters of terephthalic and isophthalic acids with glycols, heat-fusible polyamides, polystyrene and vinyl polymer resins. Low melting point resins include thermosetting e.g. phenol aldehyde, melamine aldehyde and epoxy resins, and thermoplastic e.g. the gasoline-insoluble residue from the distillation of pine tar (Vinsol resins), and low molecular weight polystyrenes. The adhesive may include a colouring material, either in powder form or applied as a dispersion or solution in a volatile liquid, which becomes visible on heating whereby it is clear to which parts of the surface to be bonded the adhesive has been applied. Suitable colouring materials are pigments, e.g. carbon black, chromium oxide, iron oxide, cadmium red and flake aluminium pigment or dyes such as " Resoform Brown B.R. Pure " and " Natural Oil Brown," or a highly coloured resinous material such as a resorcinol-formaldehyde resin. The method and apparatus may be used to bond shoe uppers to insoles in a conventional lasting press. Specification 962,851 is referred to.