Process for the production of non-woven cotton fabrics having a patterned structure

Claim 1

Process for producing a nonwoven fabric which comprises: (a) supporting a layer comprising at least a major proportion of gray cotton fibers which are free from any artificial binder and which are in contact with each other but which are capable of movement under applied liquid forces, on a liquid pervious support member adapted to move in a predetermined direction and on which fiber movement in directions both in and at an angle to the plane of said layer is permitted in response to applied liquid forces, said liquid pervious member being a foraminous mesh formed of a plurality of first substantially parallel lines of filaments and a plurality of second substantially parallel lines of filaments crossing the first said lines to form fixed crossing positions where the first and second substantially parallel lines cross, the crossing points providing a predetermined pattern of high points with valleys existing between adjacent high points, the said foraminous mesh having a regular pattern of holes therein between the lines of filaments and extending over the whole area thereof, the said holes occupying at least 30% of the area of the pervious member; (b) moving the liquid pervious supporting member with the supported layer of fibers thereon in said predetermined direction through a fiber rearranging zone within which spaced-apart sprays of liquid from individual jets are projected directly downwardly in a substantially vertical direction at a pressure of from about 700 to about 4 300 kpa onto said layer from a plurality of nozzles or jets positioned above the layer while oscillating the nozzles or jets in a direction transversely of the said predetermined direction of travel at a frequency of oscillation of from about 60 to about 300 cycles per minute and at an amplitude of from about 5 to about 100 millimetres, the momentum transferred from the liquid coming from the nozzles or jets onto the fibers being greater than 230 kg metre/sec/metre²; (c) permitting said sprays of liquid from the nozzles or jets to pass through said layer and said foraminous support member to effect movement of said fibers from over those portions of the support member where there are high points towards the valleys of the support member to form a patterned layer characteristic of the said liquid pervious foraminous support member, and to effect sufficient mechanical engagement of said fibers in the portions over the valleys to produce a self-supporting coherent layer without utilising any artificial binder; and (d) subjecting the self-supporting coherent layer of step (c) to a cotton scouring step to remove natural oils and waxes therefrom, thereby obtaining a coherent fabric having a pattern of a plurality of apertures therein, and a tensile strength which is at least as great for the wet fabric as for the dry fabric when measured in both the directions transverse of and longitudinally of the direction in which the cotton fibres were moved.