PAPER OR NON-WOVEN FABRIC OF REGENERATED CELLULOSE FIBERS AND METHOD FOR PRODUCING THE SAME

1394085 Paper; non-woven fabric MITSUBISHI RAYON CO Ltd 28 June 1972 30219/ 72 Heading D2B A method of making a paper or non-woven fabric comprising regenerated cellulose fibres comprises (a) dispersing spun and stretched fibres comprising hydroxy methyl cellulose xanthate in an aqueous medium having a pH lower than 6.0 at a temperature lower than 30‹C; (b) forming the fibres into a web by a wet-forming method; (c) dehydrating the web to an extent that the "process moisture percentage" of the web is lower than 700%, the fibres after dehydration being characterised by (1) a γ-value greater than 30, (2) a "decomposition degree" less than 75%, and (3) a "process swelling degree" less than 250%; (d) subjecting at least a portion of the surface of the dehydrated web to a pressure greater than 2 Kg/cm at 90-180‹C, thereby fusing and decomposing the hydroxymethyl cellulose xanthate in the pressed portion and simultaneously bonding the fibres in said portion to each other, and (e) subjecting the pressed web to a regeneration treatment to decompose remaining hydroxymethyl cellulose xanthate into cellulose. The aqueous medium in which the hydroxymethyl cellulose xanthate fibres is dispersed may contain dispersing agents such as polyethylene oxide, carboxymethyl cellulose, sodium polyacrylate, polyacrylamide, and various latexes. The surface of the dehydrated web may be fused over an area from 5 to 40% of the total surface area of the web. Embossing rolls or smooth rolls in association with a plastics net may be used for this purpose, (Figs. 4, 5 not shown). The fused areas may form a spotted pattern and small holes may be formed in such areas. Use of a roll at high temperature but relatively low pressure produces a web having one side fused and transparent. The hydroxymethyl cellulose xanthate fibres may be blended with fibres which do not fuse at 90-180‹C e.g. pulp, rayon, acrylic, polyester, polyamide, and acetate fibres. Regeneration may be carried out with an aqueous acidic solution at a temperature higher than 50‹C. The fibrous parts of the pressed web may be subjected to shrinkage or crimping during regeneration by a two-stage aqueous acid treatment. The product may weigh from 10- 200 g. per square meter and may be used in the manufacture of tampons, pads, sheets, table cloths, diapers, curtains inter alia.