Verfahren zur Herstellung mikroporoeser wasserdampfdurchlaessiger Flaechengebilde nach dem Polyisocyanat-Polyadditionsverfahren

摘要

1,225,186. Laminated microporous structures. FARBENFABRIKEN BAYER A.G. 6 Aug., 1968 [9 Aug., 1967], No. 37432/68. Heading B5N. [Also in Divisions B1-B2 and C3] Porous substrates such as leather, woven or knitted textiles, felts, fabrics, paper or cardboard may be laminated to microporous sheet structures which are permeable to water vapour and are prepared by (a) forming a 10 to 70 weight per cent solution of a prepolymer in an organic solvent which prepolymer (1) contains at least 2 functional isocyanate or hydroxyl and/or secondary amino groups, (2) contains at least 2% by weight of free isocyanate groups or if it contains hydroxyl and/or secondary amino groups it should have a content of hydroxyl and/ or secondary amino groups such that the calculated M.W. is below 20,000 and/or the Shore A hardness is below 35, (b) reaction of this prepolymer solution with another compound or compounds which are capable of undergoing polyisocyanate polyaddition using an NCO/OH (NHR) ratio of 0À95 to 1À30, if desired in the presence of a catalyst, (c) addition of at least one further solvent, a "non-solvent" which (1) is miscible with the solvent in step (a) and with the starting materials for the polyaddition in the proportions used, (2) has a relative evaporation number higher than that of the solvent used in step (a), and (3) has practically no solvent action on the end product; (d) shaping the solution while both the solvent and non-solvent are allowed to evaporate, both step (c) and the shaping being carried out before the polyaddition reaction of step (b) is complete. The microporous sheet structure is preferably transferred to the porous substrate by the reverse process and attached to it by discontinuous layers of adhesive. In Example 5 a polyurethane-urea foil is applied by the reverse process to a bonded polyester fibre fleece. Reference has been directed by the Comptroller to Specification 1,150,995.