GB1475115A - Application of polyurethane emulsions to woo - Google Patents

Abstract

1475115 Rendering wool shrink resistant DUNLOP AUSTRALIA Ltd 18 June 1974 [27 Aug 1973] 27059/74 Heading D1P Wool, wool fabrics or wool articles are rendered shrink-proof and optionally crease proof by impregnation with an aqueous emulsion or dispersion of a polyurethane having one or more disulphide or polysulphide groups and curing the polyurethane impregnated wool by dry heat steam or boiling water. Preferably the polyurethane is a reaction product of (a) an organic polyol or mixture of polyols having at least two hydroxyl groups and an equivalent weight of 1000 to 3000, (b) an organic polysulphide having at least two thiol groups and an equivalent weight with respect to the thiol groups not exceeding 2000 and (c) an organic diisocyanate and (d) water. The organic polysulphide (a) constitutes from 20 to 80 mole% and from 5 to 33% by weight of the combination of (a) plus (b) and the organic diisocyanate (c) is used in a ratio of I to 2.5 equivalents of (a) plus (b) and 2 to 3.5 equivalents per equivalent of (a). Polyol (a) is obtained by reacting propylene oxide with glycerol or trimethylol propane and may be ethylene oxide tipped. Organic polysulphide (b) is preferably obtained by condensing sodium polysulphide with bischloroethyl formal and has 1 to 50 preferably 6 polysulphide groups in the chain. Specified isocyanates are 2, 4 or 2, 6 toluene diisocyanate, diphenyl methane diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate and dicyclohexyl methane diisocyanate. In example I 200g of (a), 1.1g of phenyl mercuric acetate catalyst and 50cc of toluene are preheated to 70‹C and reacted with 26g of toluene diisocyanate. After 1 minute 50g of (b) is added and after 10 seconds the composition is quickly homogenised with an aqueous solution containing 5g polyoxylated alkyl phenol and 9g of alkyl trimethyl ammonium bromide as emulsifiers and 3.8g of methyl cellulose as emulsion stabiliser. The emulsion is diluted to 5% solids and padded onto a plain weave worsted or a knitted Jersey fabric to give 80 or 100% wet pickup. The impregnated fabric may be cured at 100 to 150‹C or made into a garment and then hot pressed to provide a permanent crease. In an alternative preparation method reactants (a), (b) and (c) are mixed together. The emulsion may contain as cross-linking agents for the wool and/or the polyurethane up to 10% by weight of the polyurethane of a dibromo or dichloromethylene compound, an aminimide, a ketoxime blocked isocyanate, a water soluble diepoxide an aldehyde or an aldehyde donor.