Patent GB-1364601-A (GB)
Title: Treatment of sheet materials
IPC: D06C21/00
Filed: 1972-02-16
Abstract: 1364601 Shrinking fabrics R R WALTON 16 Feb 1972 [16 Feb 1971] 7208/72 Heading D1S A method of treating a running length 16 of flexible material comprising, by means of a confining surface 12, pressing the material 16 against a moving drive surface 10, and beyond the surface 12, engaging one side of the material 16 with a retarding surface 14 while the other side remains exposed to the surface 10, is characterized in that the surface 12 is positioned at least in part closer to the surface 10 than is the surface 14, the pressing action is continued to cause the material 16 to travel with the surface 10 without slippage relative thereto to a point in the vicinity of the beginning of the surface 14, and the surface 14 having projecting portions thereon to grip and release the material 16 and is fixed and is inextensible in the direction of travel of the material 16. The material 16 may be a woven, non- woven or knitted fabric, e.g. nylon tricot, or paper. The treatment may longitudially shrink, crepe or merely bulk or thicken the material. In one embodiment, Fig. 1, the surface 10 is the surface of a driven roll and the surface 14 is substantially rougher than the smooth surface 12 and is preferably rougher than the surface 10. Preferably, the surface 10 is coated with tiny hard particles and the surface 14 has gripping projections of hard, wear-resistant material. The surface 14 is resiliently supported in the direction of the thickness of the material 16. In the treating system shown in Fig. 5, the surface 10 is driven by a device 80 which also drives a take-up roll 90, e.g. the speed of the surface 10 being 2% faster than the surface speed of the roll 90. The system may be used to treat a lamination of a layer of scrim threads sandwiched between two no-woven wet laid sheets and two external sheets of tissue paper. The laminate passes from a supply roll 160 to a roll pair 170 for forming fine longitudinal corrugations. The laminate may be pre-treated by a radiant heater 172, a steam heated or chilled roll 174 and a steam, water or chemical spray 176 and post-treated by a dust collector 178 and a heat set or chill roll 180. In another embodiment, Fig. 6, the surface 10 is formed by a cylindrical roll 20, the surface 12 is defined by a member 22, e.g. of iron-nickel alloy, and the surface 14 by a non-resilient fabric 24 having a coated grit facing, e.g. emery cloth. A relatively thick and unyielding keeper sheet 28 is provided and a spring steel keeper 26 is inserted between the sheet 28 and the fabric 24. The assembly 22, 24, 26, 28 extends as a cantilever and is pressed towards the roll 20 by a member 30 which is adjustable towards the roll surface to vary the pressure and lengthwise along the assembly to alter the point of application of pressure. The surface 12 may have a polytetrafluoroethylene coating. Instead of emery cloth, the surface 14 may be formed by a thin metal mesh or metal or other hard fibre weave in which the crossing elements form projections; finely perforated dimpled or scratched metal plate; fixed brush or needle-like projections; or a metal plate having tiny tungsten carbide particles adhered thereto by a plasma coating technique or a gun shot technique. In a further embodiment, Fig. 7, the drive surface is defined by parallel knurls and grooves 10a extending at an angle of 50‹ to the axis of the roll. The end 25a of the member defining the confining surface is cut at an angle of 45‹ to assist in directing the material forward. The retarding surface is formed by an emery cloth 24b and a flexible silicone rubber keeper 26b backed by a steel upper keeper (not shown) is provided. In a still further embodiment, Fig. 8 (not shown), the confining surface is formed by a polytetrafluoroethylene impregnated blue steel sheet and the retarding surface is formed by an emery sheet 110. A further blue steel member 120 lies above the sheet 110 and has an extension 120a to press the web 16 against the surface 10. A resilient member 130, e.g. of natural rubber, extends over the member 120 and has a blue steel keeper plate 133 thereabove. A member 134 has a presser edge 125 and an auxiliary presser 136 extending therefrom. In a further embodiment, Fig. 11 (not shown) the emery retarding member has a backing member of a leather substitute material. In modifications (not shown), the forward edges of the members defining the confining and retarding surfaces may be inclined at an angle to the axis of the drive roll and curved or flexed to conform to the roll. To impart "two-way stretch" to the material, it may be passed successively through two such machines having the angle inclination in opposite directions.