| 摘要 |
1,150,995. Microporous polyurethane coating; mixing apparatus. FARBENFABRIKEN BAYER A.G. 25 Oct,, 1967, No. 48442/67. Headings B1C, B2E and B2K [Also in Division C3] Substrates e.g. glass plates, metal plates, silicone rubber matrices, split leather, grain leather, knitted or woven textiles, fleeces, felts, paper or cardboard may be coated with microporous polyurethanes prepared by dispersing a nonameric polyisocyanate or an N.C.O. terminated prepolymer in at least 40% by weight, based on the polyisocyanate or prepolymer, of a non-solvent therefor, in the absence of an emulsifier, and reacting the dispersion so formed with a substantially equivalent quantity of a compound which contained at least two active hydrogen atoms or at least two and not more than six nitrogen atoms, the reaction mixture so obtained being applied to the substrate before reaction is complete and the solvents present being subsequently removed. The monomeric polyisocyanates and prepolymers may be used dissolved in an organic solvent. Conventional polyisocyanates are used and prepolymers thereof based on polyethers and polyesters are suitable. The preferred non-solvent is water, but glycols, aliphatic hydrocarbons and commercial mixtures may be used. Conventional aliphatic and aromatic diamines may be reacted with the dispersions, as may hydrazine, semicarbazide, carbodihydrazide, guanidine, N,N' - dimethylurea and phenylguanidine. Catalysts such as tertiary amines or organotin compounds be used in the reaction with the polyamines. Suitably half to three-quarters of the reactive groups should have undergone reaction before the reaction mixture is applied to the substrate. The mixer comprises a mixing chamber 1 provided with a pinned-disc stirrer 2 and a tempering unit 3 surrounding the mixing chamber. Feed pipes 4 and 5 are provided with shut-off valves 6 and 7 and inlet nozzles 8 and 9. The outlet 10 is provided with a variable throughflow cone valve 11 which tapers towards the applicator nozzle 12. |
