GB920475A - - Google Patents

Abstract

920,475. Polyamines from polyisocyanates. FARBENFABRIKEN BAYER A.G. July 5, 1961 [July 9, 1960], No. 24363/61. Class 2(5) [Also in Group IV(b)] Polyamines are produced by reacting an aliphatic or cycloaliphatic polyisocyanate, or an adduct prepared by reacting such an isocyanate with a polyhydroxy compound and containing free isocyanate groups, with amidosulphonic acid (HO.SO 2 .NH 2 ) in aqueous solution. The -NCO groups are thereby replaced by -NH 2 groups, but some of the -NCO groups react with water and thus lengthen the chain through urea-type linkages. At room temperature, the urea-linkage-forming reaction is suppressed, but at ca. 40‹C. and above, the products have a higher molecular weight and lower amine-group content. The isocyanates are preferably stirred into the amidosulphonic acid solution, at room temperature if low molecular weight products having a high NH 2 content are desired, and the mixture heated to complete the reaction at up to 50‹C. The initial emulsion changes a solution on completion of the reaction, and the amine may then be precipitated by the addition of a base. In the examples, (1) a polypropylene glycol (OH number 270, mol. wt. 410)-hexamethylene diisocyanate adduct; (2) as (1), the polyglycol having OH number 112, mol. wt. 1,000; (3) as (1), octaethylene glycol ether replacing the polypropylene glycol; (4) hexamethylene diisocyanate per se are used. Other isocyanates which may be used are: tetra- and hexamethylene diisocyanate, p-cyclohexylene diisocyanate, their adducts with polyols, e.g. 3 mol. hexamethylene diisocyanate with 1 mol. trimethylol propane. Adducts of polyisocyanates with linear or branched polyethylene glycol ethers, polypropylene glycol ethers, polyesters, polytetrahydrofurans, polythioethers or polyacetals may be used. The products react with isocyanates at room temperature, are suitable as smoothing agents for textiles or stripping agents for vat dyeings, and may be used to harden epoxy resins.