| 摘要 |
1396131 Laminating method: extruding and calendering H W TENGE 19 May 1972 [21 May 1971 (2) 22 May 1971 27 May 1971 (2) 5 May 1972] 23656/72 Headings B5N and B5A [Also in Division H1] A method of laminating together two or more foils of unsintered PTFE comprises the steps of subjecting the foils to both compression and friction between at least one pair of co-operating laminating members such that the strain constant A k has a value of 0À155 Œ 0À15 and sintering the laminate so produced. The strain constant A k is defined by the equation A R = K 1 . S 1 where K 1 is the compression component of the force exerted by the members on the foils and is expressed by the ratio f 1 /F, where f 1 is the total thickness of the foils in the final laminate and F is the total thickness of the foils prior to lamination; and S 1 is the frictional component of the force exerted by the members on the foils and is expressed by the ratio a/(b.Á) where a = f-f 1 , b is the distance in the direction of travel of the foils over which lamination is effected and Á is the coefficient of friction of PTFE. In a preferred embodiment a plurality of parallel elongate electrical conductors are interposed between two by the method of the invention to form a signal ribbon cable, the conductors being in the form of wires. Alternatively, glass fibres, heating elements, foils, nets, magnetic elements or tubes may be bonded between two foils of PTFE. In the embodiment shown in Fig. 1, wires 8 from reels 6 are interposed between unsintered PTFE foils 5 and the assembly subjected to compression and friction by calender rollers 2 prior to being fed through sintering over 10, 11 and cooling bath 12. The laminating members may be profiled or flat, rotating or non-rotating. The foils may be formed by extrusion, may have a diagonallytransversely-axially oriented structure and may contain fillers, e.g. metal or carbon powder, glass fibres or quartz powder. Fig. 9 shows a paste extruder in which PTFE paste 107 is compressed by piston 106 and extruded, the extruder being provided with a head 108 which rotates in one direction and an orifice 109 which rotates in the opposite direction, the resultant foil being fed through the calender. Fig. 10 (not shown) relates to a similar assembly without the rotating head and orifice. |
