METHOD FOR PRODUCING A FLEXIBLE COMPOSITE ELASTOMERIC POLYURETHANE SKIN

摘要

The present invention relates to a method for producing a flexible elastomeric composite polyurethane skin comprising a first and a second flexible polyurethane layer obtained by spraying a first and a second polyurethane reaction mixture onto one another. The first reaction mixture is an aliphatic polyurethane reaction mixture which is free of lead and formulated to produce a polyurethane elastomer having a flexural modulus smaller than 35 MPa. The second reaction mixture is an aromatic polyurethane reaction mixture producing a polyurethane elastomer having a smaller flexural modulus. The thickness of the aliphatic polyurethane layer could be made so small with respect to the thickness of the aromatic polyurethane layer that the composite skin has an average flexural modulus smaller than 30 MPa. Notwithstanding the lower reactivity of the aliphatic polyurethane reaction mixture, especially when using a higher NCO-index to reduce the "rubbery feel" and the emission of VOCs and/or a flexibiliser to achieve a higher flexibility, sufficiently short cycle times can be achieved due to the accelerated curing observed when spraying the aromatic polyurethane sufficiently early against the aliphatic polyurethane layer.