Patent GB-1171111-A (GB)
Title: Sheet Material of Polymeric Substances and Method for Producing said Material.
Inventor: RASMUSSEN OLE-BENDT
IPC: B29C48/315
Filed: 1965-06-24
Abstract: 1,171,111. Extruding sheet materials. O.-B. RASMUSSEN. 23 June, 1966 [8 June, 1965; 24 June, 1965], Nos. 24068/65 and 26708/65. Heading B5A. [Also in Division D1] An extruded synthetic plastics sheet is made of elements each comprising a spine 4, Fig. 2, and fibrelike tentacles 3, the elements being held together by felting and/or bonding the tentacles. The basic method of making such a sheet is by extruding a product comprising lamellae of two diverse materials, the lamellae of one material alternating with the lamellae of the other, Fig. 1 (not shown), and forming the tentacles from the lamellae of one material only. The tentacles are generally felted in layers which preferably lie in the flat surfaces of the sheet and the tentacles of any one element may be felted with those of one or more other elements. Variously shaped elements are described having two sets of tentacles, Figs. 3-5 (not shown), and one set thereof, Figs. 6, 7 and 8 (not shown), the shape depending largely on the force exerted on the lamellae during formation of the tentacles. The elements are arranged so that the spines traverse the whole or part of the thickness of the sheet and with elongated spines they may also traverse the width of the sheet. In a modification, Fig. 9 and Fig. 10 (not shown), tentacles 10 are punched from the central portions of spines 7 and pass through holes 9 in adjacent spines. Tentacles at the ends of the spines may or may not be provided. A preferred material for the elements is nylon and the second material is generally less viscous and is either completely or partially removed or is distinctly modified in the final product. A preferred second material is nylon mixed with polyoxyethylene. The second material may be removed by the use of a suitable solvent or modified by being foamed or split into fibres which join the elements, e.g. by rolling or flexing the sheet. With the abovementioned mixture of nylon and polyoxyethylene the latter component is washed out and the remaining nylon is split into fibres. Suitable polymers for the elements, in addition to nylon or other polyamides, are polyesters, polyurethanes, polypropylene, polyethylene, P.V.C., copolymers of polyvinylidene chloride, high impact polystyrene and polycarbonates. Prepolymers may be extruded. Not all of the elements need be of the same composition or colour. The second material may be of the same material as that of the elements, the polymers being of different molecular weights, of a different polymer or of a non-polymeric material, e.g. a paste formed from a mixture of lubricant and thickening agent. Uses of the sheet material mentioned are (i) as a textile material (after suitable calendering and removal of the second material), (ii) as a floor covering (second material preferably removed), (iii) as a leather-like product (second material in fibre form), and (iv) as packaging or building material (second material foamed). Extrusion apparatus.-In the embodiment of Fig. 11, the element-forming material I is shown shaded and is fed through ducts 13, the second material II being fed through ducts 14. Above the ducts are series of wedges 15. The wedges and/or the ducts are reciprocated laterally and the laminated materials are cut by serrated edges 18 into lamellae 23. Further serrated edges 17 on one or both sides of wedges 15 produce tentacles in material I and the tentacles are felted by a comb 24 formed by the upper edges of the wedges. From the wedges the materials pass through a die (19), Fig. 12 (not shown), and orifice (20). Die (19) may reciprocate and the jaws defining orifice (20) may reciprocate in opposite directions to stretch the elements. Further, a knife edge situated in the orifice may extend the tentacles. In a second embodiment, Figs. 14, 15 (not shown), comb 24 is omitted and orifice (20) is provided with a knife edge (26). In a modification, Fig. 20 (not shown), a needle (27) is provided which reciprocates across orifice (20) to form tentacles in the central portions of the elements, see Fig. 9, and may also rotate to twist the tentacles together. In the embodiment of Figs. 16, 17 (not shown), the wedges are omitted, and the tentacles are formed by a serrated edge (31) and knife edge (28) formed adjacent orifice (20) in a reciprocating die (19). Needles (27), Figs. 18, 19 (not shown), may be provided in ducts 14. In a final embodiment, Fig. 21, material I is supplied to duct 33 and material II to duct 32, the ducts being separated by a wall 34 having a serrated leading edge 35. A gate 36 is reciprocated to alternately communicate with ducts 32, 33 and sliding motion of the gate past serrated edge 35 produces tentacles in material I. The gate is also provided with comb-like portions to felt the tentacles. Also mentioned is the use of an annular die with relative rotation of the lamellae and ducts so that the lamellae are helically arranged in the extruded tube, the tube being subsequently cut to form a flat sheet.