Patent GB-1405921-A (GB)
Title: Nonwoven fabrics
IPC: D04H1/435
Filed: 1972-09-01
Abstract: 1405921 Non-woven fabric CIBA-GEIGY AG 20 Aug 1973 [1 Sept 1972] 40651/72 Heading D1R [Also in Division C3] A process for making a nonwoven fabric comprises impregnating a mass of loosely assembled fibres with a polymercaptan containing, per average molecule, at least two mercaptan groups and with a polyene having, per average molecule, at least two ethylenic double bonds each beta to an atom of oxygen, nitrogen or sulphur the sum of the mercaptan groups in the polymercaptan and the ethylenic double bonds in the polyene being more than 4, preferably 5 to 8, the mixture of polymercaptan and polyene comprising 5 to 25% by weight of the fibres, the mixture being cured or allowed to cure to produce a self-sustaining fabric. The fibres may be continuous or of length 1-5 mm or 1-5 cm and of cotton, ramie, jute, linen, viscose, polyamide, polylactam, polyester, polyvinyl chloride, polypropylene, polyacrylonitrile, mineral wool, silk, glass, asbestos, wool and blends thereof. The fibres may be corded to form an orientated web or air laid or wet laid to form a random web. The polyene and polymercaptan may be applied seperately or more conveniently together in the form of an aqueous or non aqueous solution, dispersion or emulsion, or as a powder by spraying dipping or coating and calendered or centrifuged to remove excess. The binder may be printed in the form of discrete stripes or spots. Curing may take place at room temperature or at 35 to 180C. Supplementary bonding may be provided by needling, stitching or heating to autogeneously bond thermoplastic fibres. Thickening agents such as bentonite, kaolin, starch, cellulose ethers and esters, polyacrylic acid, polyvinyl pyrrolidone, polyvinyl acetate, hydrolysed polyvinyl acetate, urea-formaldehyde and melamine-formaldehyde may be used. The polymercaptan may have a molecular wt. of 500 to 10,000 and up to 6 mercaptan groups per molecule. Many polymercaptans are specified, those exemplified being glycerol trithioglycollate, propane-1, 2-diol dithioglycollate, propane-1-3-diol dithioglycollate, pentaerythrital tetrathioglycollate, 1, 1, 1, trimethylolpropane trithioglycollate, 1, 2-bis (2-mercaptoethoxyane), the trithioglycollate of a poly (oxypropylene) triol (i.e. a glycerolpropylene oxide adduct) of M. Wt. 600, a tri (2 hydroxy- 3 mercaptopropyl) ether of a M. Wt. 480 glycerol-propylene oxide adduct and mercaptanterminated polyesters made by heating 1 mol glycerol, 4 mol adipic acid, 4 mol butane-1, 4- diol and 3 mol thioglycollic acid, or heating 3 mol poly (oxypropylene glycol) of M. Wt. 1025, 2 mol of thiomalic acid and 2 mol of thioglycollic acid, or heating 3 mol poly (oxyethylene glycol) of M. Wt. 600, 2 mol thiomalic acid and 2 mol thioglycollic acid. Preferably the polyolefine has a molecular weight of 250-10,000 and has up to 6 ethylenic double bonds alpha to a carbonyloxy group. Many polyolefins are specified those exemplified being a glycerol polypropylene oxide adduct condensed with maleic anhydride, acrylic acid, methacrylic acid or maleic anhydride followed by n-butyl glycidyl ether and the adduct of the diglycidyl ether of 2, 2-bis (p-hydroxyphenyl) propane and acrylic acid. The reaction of the polymercaptan and the polyene may be catalysed by a Bronsted acid, a Bronsted base or a free radical former. In example 1 a web of polyester or regenerated cellulose is padded to 100% uptake with a liquor comprising 30 parts of a 50% aqueous emulsion of glycerol trithioglycollate, 300 parts of a 50% aqueous emulsion of an adduct of glyceral-propylene oxide (M. Wt 4000) and maleic anhydride, 5 parts of sodium carbonate decahydrate and 665 parts water. The impregnated web is heated to 120C for 5 minutes to yield a soft springy fabric.