Patent GB-1206188-A (GB)
Title: Improvements in and relating to laminated materials
IPC: B32B27/00
Filed: 1967-11-28
Abstract: 1,206,188. Laminates. POLYMER PROCESSING RESEARCH INSTITUTE Ltd. 28 Nov., 1967 [28 Dec., 1966], No. 54154/67. Heading B5N. [Also in Division B2] A laminate is produced by forming a film, e.g. of a thermoplastic polymer, with a number of substantially parallel slits, stretching the film perpendicularly to the common direction of the slits so as to open out the latter and to form a number of fibrous elements joined into a network, and laminating the network to a layer of thermoplastic polymer or masticated rubber under pressure and heat at a temperature within the softening temperature range of the layer but not high enough to soften the network, the weight of the network being 10 to 80 % the weight of the whole laminate. Alternatively, instead of the preformed layer, a latex or emulsion of a film forming polymer may be used to impregnate the network and then dried before applying the pressure and heat. In both methods, the softened layer or latex permeates the open slits of the network and covers the latter. To form the network, the film may be stretched and then split on the surface of a rotating abrasive member. Spreading of the split film to form the network may be effected either by passing the film through a duct through which air flows for carding the fibrous elements, or by passing the film in a tortuous path over a number of spaced bars, or by charging the fibrous elements electrostatically, e.g. by the action of the rotating abrasive member, consequent repulsion between adjacent elements causing the spreading. During lamination, the network may be held under tension applied longitudinally of the slits. Two or more of the laminates may themselves be laminated together. In such a multiply laminate, the fibrous elements may all be parallel or the elements in one layer may be perpendicular to those in an adjacent layer. A single laminate may alternatively be bonded to a paper sheet, a foamed polymer sheet, fabric, veneer, metal sheet or foil, clay, finely divided powder material or an abrasive powder. The laminate may be embossed between metal or cloth belts or between embossing rolls. The laminate may be perforated. The network may comprise a number of spread, split, narrow, parallel, spaced tapes. The network may be formed from a film of polyethylene, polypropylene, P.V.C., polyacrylonitrile, polyvinylidene chloride, polyvinyl alcohol, a fluorine-containing polymer, a polyester, a polyamide or a regenerated cellulose or cellulose-derivative. The layer to which the network is laminated may be of low density polyethylene soft P.V.C., polystyrene, polypropylene or a biaxially stretched polymer film. Several layers of spread, connected, fibrous elements may be laminated to the softened layer. The fibrous elements of adjacent layers may be parallel or perpendicular, or at random angles to each other. The fibrous elements, when formed from narrow bands, may be arranged in spaced parallel bands within the laminate. Overlying perpendicular sets of these spaced bands may be arranged to form a chequered pattern. The materials of the network and of the softenable layer may be similar, e.g. P.V.C. and plasticized P.V.C. respectively.