GB1326915A - Perforated non-woven fabrics - Google Patents

Abstract

1326915 Perforated non - woven fabrics CARL FREUDENBERG 26 Nov 1970 [26 Nov 1969] 56272/70 Heading D1L Apparatus for producing a perforated non- woven fabric comprises an endless screen 1 passing around a system of rollers 2, 3, 4 and 5. A first duct 6, to which a slurry of fibres is continuously pumped with vigorous agitation leads up to the screen 1 and discharges onto the screen 1 over an area above a system of suction boxes 7. Water from the slurry is thus sucked through the screen 1 and a fleece is collected on the screen. The fleece is then carried upwards, on the screen 1, until it comes between a stencil 8 and the screen 1. The stencil 8 is cylindrical and rotates at a velocity such that the parts of the screen and stencil adjacent to one another move at the same speed in the same direction as one another. The stencil 8 rotates around a cylindrical duct 9 that extends across the width of the screen and that has an outlet slot 10, also extending across the width of the screen, leading from it and directed at right angles towards the screen. Water is forced into the duct 8 under pressure, emerges through the slot 9 and is divided into jets by the stencil 8. Removal of the water through the fleece is promoted by the suction box beneath the fleece at this position. The perforated fleece is then dried after leaving the screen. In a modification there may be two endless filtration screens, with a first duct discharging onto one screen and a second duct discharging onto the other. The slurry should be a very dilute suspension of fibres in water, e.g. 0.01 to 0.5% fibres by weight. Another fluid other than water used for making the perforations is an aqueous slurry of textile fibres. In order to stabilise the perforations and to strengthen the fleece it is generally necessary that the fleece should contain a binder which may be activated by heat, e.g. in the drying stage.