Patent GB-808433-A (GB)
Title: Improvements in and relating to processes and apparatus for the manufacture, in a single continuous operation, of a flexible sheet of reinforced plastic material
Filed: 1956-02-24
Abstract: 808,433. Fabrics composed of agglutinated threads; laminates; coated fabrics. VANLAER, P. G. E. A. Feb. 24, 1956 [Feb. 25, 1955], No. 5901/56. Class 140. [Also in Group IX] A process for the continuous manufacture of a flexible sheet of plastic material with a reinforcement having bi-directional resistance includes the steps of forming a reinforcing sheet by advancing longitudinal rovings or threads in the direction of their length along a guide surface formed at the inlet end substantially by the envelope of a circular cylinder and degenerating progressively towards the outlet end into the envelope of substantially flattened cylinder conforming to a straight edge, the circumferential length at the outlet end being substantially equal to that at the inlet end and by winding transverse rovings or threads in generally sinusoidal turns around the longitudinal rovings or threads, at a position where the latter still follow a path formed substantially by the generatrices of the said circular cylinder in such a manner that the transverse rovings or threads assume a rectilinear configuration in the finished sheet ; and applying plastic material to the sheet thus formed. As shown, the longitudinal threads, 1, Fig. 3, drawn from beams 2 by drums 3, travel over bar 4 and around the periphery of elliptical guide 5 and thence into the teeth of circular comb 6 which distribute the threads around the periphery of a section of a cylinder envelope 7 whose end 8 assumes the shape of a completely flattened cylinder. Cones or coaps of transverse threads 9 are mounted on ring 10 which can rotate on rollers 11 and bearing race 12. The transverse threads pass through tensioning devices 14. The revolution of ring 10 winds the transverse threads around the longitudinal threads, disposed in tubular formation, in a series of spirals. The tubular assembly of threads is progressively transformed into a flattened tube which, when it reaches the flat end 8 of the cylinder 7 is compressed into a sheet 15 by pressure-rollers 16. The threads forming the selvages of the sheet may be thicker than the other longitudinal threads. In order to compensate for the consecutive deformation of the weft spirals, guides 17 are disposed around the circular part of cylinder 7 and the weft threads slide over the guides 17 before coming into contact with the warp threads with the result that the weft spirals are wound in generally sinusoidal form. The rollers 16 compress sheet 15 between two endless layers 19 and 20 of a large-mesh fabric which serve as conveyers for the sheet to the impregnating apparatus where both sides of sheet 15 receive an application of liquid or pasty plastic material 22, Fig. 4, by contact with rotating application drums 21. The plastic is applied to sheet 15 through the meshes of the conveyer fabric, the quantity applied being controlled by knives 23, and is compressed into the fibres of sheet 15 by pressure rollers 25. The sheet then passes through drying ovens 24 and is wound by cylinders 27 to form roll 28, the conveyer fabric 19 and 20 being drawn back to pressure rollers 16 by passing over rollers 26. Specified impregnants are latex and polyester resin. In alternative embodiments impregnation may be carried out by means of knives or atomizers; and the conveyers 19 and 20, instead of being of the endless type, may consist of pieces of large mesh fabric of suitable length which are reeled at the same time as the impregnated sheet. There may be applied, by means of pressure rollers, to each side of the sheet, after impregnation, an impervious film, e.g. of regenerated cellulose, which is only separated therefrom at the time of use, e.g. for making laminated plastic mouldings. One or both layers of film may be replaced by layers of felt, fabric, or carded fibres. A composite material composed of two thick layers of fibres and a core of unwoven threads may be obtained by replacing the two layers of conveying fabric 19 and 20 with layers of fibres which are compressed with the threads, the resulting assembly being impregnated, dried, and formed into a roll. Instead of impregnation by a liquid there may be similarly applied to each side of the sheet a film of thermoplastic material which is moulded thereto by means of heated pressure rolls. The reinforced plastic sheet of the invention may be covered with wool combings and perforated, to form a material suitable for garments. Alternatively, a material resembling fur or velvet may be made by first sticking hairs on to a support by an easily removable adhesive such as a water-soluble gum, and then bringing the free ends of the hairs into contact with the plastic resin impregnating the sheet. The support is removed when the hairs are secured to the resin-impregnated sheet. Devices adapted to stop the machine in the event of breakage of one of the transverse or longitudinal threads are described (see Group IX).