Composite element comprising a top layer and a base layer of thermoplastic polyurethanes, its preparation, and its use

A composite element built up from

• A) an elastic, cellular polyurethane sheet-like structure comprising a thermoplastic polyurethane as the top layer, having an essentially pore-free surface, said top layer having been prepared by sintering a thermoplastic polyurethane in the presence of a solid blowing agent which is solid at 23.degree. C., and
• B) a thermoplastic polyurethane elastomer (B) as the base layer, which is itself prepared by reacting
• (Ba) 1 mol of at least one essentially linear polyesterol or polyetherol having a molecular weight of from 600 to 3000,
• Bb) from 6 to 15 mol of an organic diisocyanate, and
• Bc) from 5 to 14 mol of at least one alkanediol or dialkylene glycol,
• in the presence of
• Bd) from 0.05 to 0.3% by weight, based on the total weight of (Ba) to (Bc), of water.