GB1353056A - Apparatus and method for producing a nonwoven fabric - Google Patents

Abstract

1353056 Non-woven fabric; re-arranging fibres in non-woven fabrics JOHNSON & JOHNSON 19 April 1971 [24 March 1970 (3)] 25171/71 Headings D1R and D2B A non-woven staple fibre web comprises areas of high and low fibre density formed by directing fluid through the web while it is lying on a supporting member comprising discontinuous impermeable portions surrounded by a continuous sieve-like permeable area. An apertured member may be located between the fluid directing means and the web. As shown, Fig. 1, fibre web 41 is fed between continuous running support belt 30 and an apertured member in the form of rotating drum 15, water being sprayed from nozzles 29 through the drum material and belt to rearrange the fibres. Suction boxes 43 extract water from the web. Belt 30 has, Fig. 4, a square pattern of discontinuous domed impermeable portions 51 surrounded by a sieve 50, and drum 15 has uniformly spaced apertures 19. The portions 51 may have any shape, and may be in any pattern. The apertures 19 are larger than the apertures in sieve 50, and preferably have a diameter of at least 95 microns. Each impermeable portion may have a ratio of largest to smallest dimension of not more than 4:1, e.g. not more than 1.5:1, a largest dimension of not more than one inch, and an area at least four times the area of an aperture in the apertured member. The smallest width of the sieve may be at least twice the width of, and at least twice the pitch of an aperture in the apertured member. Alternatively, Fig. 13, fibre web 143 is passed between wet-out rollers 136, 137 which preferably control the webs' moisture content to 150 to 200 p.b.w. The web is then carried on endless belt 144 beneath water jets 151 to rearrange the fibres. Belt 144 has the construction shown in Fig. 4. The sieve portion of belts 30 or 144 may be in the form of a woven wire or nylon screen, Fig. 5, having strands 85 weaving over and under straight strands 84. The kinks in strands 85 define between them troughs 87 each extending parallel to strands 84, and also troughs 88 each extending parallel to strands 85. The depth of each trough is preferably at least 28.5 microns, e.g. from 47.5 to 7.50 microns, and the distance between two adjacent kinks is preferably at least 142 microns, e.g. is at least 28.5 microns. A web, Fig. 9, produced by the apparatus of Figure 1 contains holes 101 produced by the water flowing on portions 51, and areas of low fibre density 103 produced by water flowing through apertures 19. The use of a sieve having troughs produces a web having holes lying within areas 103. The initial web may comprise one or more layers of natural, mineral or synthetic fibres which have been carded or air laid, or laid by liquid depositions. The redistribution of a web of viscose rayon fibres is exemplified. The preferred fibre length is from 0.25 to 2.5 inches.