GB1233390A - - Google Patents

Abstract

1,233,390. Microporous sheet material. FARBENFABRIKEN BAYER A.G. 9 Dec., 1968 [7 Dec., 1967], No. 58391/68. Headings C3C and C3R. Microporous polyurethane-urea sheet material is produced by reacting (1) one or more compounds containing at least two terminal NCO groups and having a M.W. of 100 to 10,000, and (2) water, as a chain-lengthening agent, in a reaction medium which comprises at least one non-solvent for the polyurethane-urea, so that the polyurethane-urea produced has (1) a Shore A hardness of at least 50, (2) a tensile strength of at least 50 kg./cm.<SP>2</SP> and (3) a softening range above 80‹ C., an at least equivalent amount of chain-lengthening agent being used, based on the amount of (1), applying the reaction medium, while it is still pourable, to a substrate and shaping the mixture and removing the reaction medium, or allowing the reaction medium to evaporate from the shaped product. The microporous material so produced may then be stripped from the substrate. If desired, an additional chain-lengthening agent which contains at least two OH or NH groups and has a M.W. of 50 to 600 may be added to the reaction mixture. The non- solvent may be, e.g. an aromatic hydrocarbon, aliphatic hydrocarbon, petroleum fractions, cycloaliphatic hydrocarbons, chlorinated hydrocarbons, esters, ketones, ethers, nitro compounds, alcohols and nitriles. They may be used in admixture with a solvent for the polyurethane-urea. Water used as the chainlengthening agent may at the same time be used as the non-solvent. Catalysts such as tertiary amines and tin compounds may be added to the reaction mixture. The NCO group-containing compound is preferably a polyurethane prepolymer, optionally mixed with a monomeric polyisocyanate. In a typical example, water is dispersed in a 25% solution in benzene of an NCO propolymer prepared by reacting a mixture of 2,4- and 2,6-toluylene diisocyanate with a polyester derived from adipic acid and diethylene glycol. After the addition of triethylamine, the dispersion is stirred, poured on to metal plates and after the polyaddition is finished, the solvent is evaporated.