Patent GB-1420497-A (GB)
Title: Heat-sealable adhesive inserts for fabrics
IPC: C09J7/04
Filed: 1973-03-23
Abstract: 1420497 Raster-like heat sealable coatings KUFNER TEXTILWERKE KG 23 March 1973 [23 March 1972 28 June 1972] 14229/73 Heading B2E A sheet substrate has a discontinuous coating of two layers of adhesives, the second layer being superimposed on the first and both layers being in the form of an evenly distributed array, the layer contacting the substrate and having a higher melt viscosity than the other. The substrate may be woven materials, knitted fabrics, fleeces, foams, natural or artificial leather, imitation skins, paper, tapestry, or wood, and the coatings may be only applied to certain areas of the substrate. The coating pattern may be linear, grid-like or helical, but is preferably spot-raster applied by engraved roller or using a perforated template. One method of producing the layers is to coat successive layers of adhesive. The first layer may then be p.v.c. having low plasticiser content, low pressure polyethylene (high melt viscosity), polyacrylates (optionally cross-linkable), polyvinyl alcohol, polyamides, or polyurethanes (optionally cross linkable) and the layer may contain copolymers -of ethylene and vinyl acetate, optionally saponified, as adhesion promotors. The second layer may then be p.v.c. haying high plasticiser content, low pressure polyethylene (low melt viscosity), non-crosslinkable polyacrylates, polyvinyl alcohol, or preferably low melting point polyamides or polyurethanes optionally plasticised. In this case the first layer is applied as a viscous or pastey resin and the second layer as a powder or flake sprinkled on the first layer or electrostatically coated before curing, drying, gelling or sintering. Another method is to coat the substrate with a resin, then apply pure plasticiser, or a solution or emulsion thereof, which difuses partially into the resin. In this case, the resin is applied as an aqueous dispersion, a powder (p.v.c. preferred) or viscous solution (polyurethane preferred). The plasticiser is then applied preferably as a powder. Sulphonic acid amide or resin-like condensation products may be used to plasticise polyamide, and p.v.c. may be plasticised with dicyclohexylphthalate. To facilitate the adhesion of the second resin layer on the first an adhesive intermediate layer may be applied, or the first layer may be treated by corona discharge. In examples: (1) insert fabric was coated with copolyamide powder by puntiform engraved roller; the layer is sintered and an adhesive solution was wiped onto the spots, the adhesive comprising the same copolyamide as used for the base layer, and plasticiser; (2) an insert fabric was screen printed with a paste of ammonium polyacrylate, ground stearic acid, and a copolyamide; a powder of o- and p-toluene sulphonic acid amides, as plasticiser, was then sprinkled on the still wet paste with the aid of beater bars and excess powder removed before drying and sintering; (3) a viscous solution of the reaction product of isocyanate lengthened polyester having free alcohol groups and a triisocyanate were screen printed on an insert fabric, and coated with copolyamide fibre flake electrostatically with the aid of beater bars.