Seeing tongue movements from outside

A highly durable sheet material using for synthetic leather is prepared by dipping a layer of a solution of a polyurethane elastomer which is derived from both a polyester having a molecular weight of 800 to 3000 and a polyether having a molecular weight of 800 to 3000 as soft segments, the molar ratio of the polyester to the polyether being from 10:90 to 65:35, and in which elastomer the weight of nitrogen atoms contained in the urethane groups ranges from 3.8 to 6 percent of the total weight of the polyurethane elastomer, into a coagulation bath composed of a solvent and a non-solvent for the polyurethane elastomer at a ratio by weight ranging from 20:80 to 70:30, thereby coagulating said layer of the elastomer into a microporous structure.