GB1400378A - Solutions of diisocyanate polyaddition products which contain free semiacetals and which are stable in storage - Google Patents

Abstract

1400378 Coated products BAYER AG 18 Dec 1973 [23 Dec 1972] 58449/73 Heading B2E [Also in Division C3] Substrates, particularly of leather, may be primed or finished with a coating solution comprising a high molecular weight diisocyanate polyaddition product in an inert organic solvent, a primary and/or secondary alcohol and (c) a semiacetal of formaldehyde corresponding to the formula: R-O-CH 2 -OH or (HO) p -R'-(O-CH 2 OH) q wherein R is a C 1-20 aliphatic, cycloaliphatic or araliphatic radical which may be unsaturated or substituted with alkylated nitrogen atoms R' is a C 2-20 polyvalent aliphatic, cycloaliphatic or araliphatic radical which may contain one or more hetero-atoms selected from N, S and O and has a valency of (p+q), (p+q) is 2 to 6 and p is 0 to 3, and the primary and/or secondary alcohol is contained in the mixture in a proportion of at least 25% by weight, based on the dissolved polyaddition product and the proportion by weight, of the semiacetal to the primary and/or secondary alcohol is not more than 4:1. The polyaddition product is suitably a polyester- or polyether-polyurethane, a polyester- or polyetherpolyurethane polyurea, a polyester- or polyetherpolyurethane polyhydrazodicarbonamide or a polyester- or polyetherpolyurethane polyamide. In specific Examples (7) a grained neat's leather vat-dyed with aniline dye and chrome tanned is primed with a solution of a semiacetal-containing polyurethanepolyurea solution, methyl ethyl ketone, ethyl glycol and toluene and dressed with a solution comprising a polyurethane-polyurea solution, a commercial ester-soluble collodion cotton, methyl ethyl ketone, ethyl glycol and toluene and (8) a re-tanned chrome neat's leather is primed with an aqueous primer composition of a commercial casein-containing leather covering dye, an aqueous dispersion of a butadiene-acrylonitrile copolymer and water and the primed leather is then coated with the dressing used in Example 7. Other substrates e.g. of glass, polypeptides, metal, wood, textiles or synthetic resin such as polyvinyl chloride, polyurethanes or polyesters may be similarly coated.