| 摘要 |
<p>1529339 Microporous polyurethane sheet materials METALLGESELLSCHAFT AG 3 Dec 1975 [17 May 1975] 49575/75 Heading C3R [Also in Division B2] A process for producing a microporous sheet structure having the appearance of artificial leather comprises coating a coagulable polyurethane solution on to a substrate to form a sheet, coagulating the solution and washing and drying the sheet, and wherein prior to the coagulation either a finishing agent for making artificial leather is mixed into the polyurethane solution or the finishing agent is applied to the free surface of the sheet of the polyurethane solution, and wherein, prior to the drying, the sheet is embossed. The embossing is preferably carried out by passing the sheet under pressure between two oppositely rotating rolls, at least one of which is polished preferably at a temperature of not more than 150‹ C. Coagulation generally takes place in a bath of water. Suitable finishing agents include castor oil, tallow, beeswax, paraffin, ceresin, stearin, linseed oil, neat's foot oil, olive oil, rapeseed oil, cotton seed oil, insect wax, wool grease, carnauba wax, montan wax and their sulphonated products, or a solution which has been obtained from a proportion of the coagulable polyurethane solution and which exhibits a different shade of colour from the said coagulable solution. The coagulable polyurethane solution is preferably one having a solids content of 15 to 35% wt. obtained by continuously mixing a solution of an NCO-terminated preadduct in a polar organic solvent into a solution of (i) a compound selected from hydrazine, hydrazine derivatives, polyols and diamines in which the two amino groups are attached to different carbon atoms, and (ii) if not otherwise present a compound having at least 3 Zerewitinov active hydrogen atoms, in a polar organic solvent, until gelling of the mixture is imminent.</p> |
