Curing of Polyurethane Pre‐polymers on Wool. I—Air, Press and Steam Curing

Abstract

After application to woo) from organic solvent, isocyanate‐terminated polyurethane pre‐polymers are usually cured by exposure to the atmosphere for 4–8 days. The activity of the resin and the humidity of the atmosphere have an important effect on the rate of curing. Complete development of the shrink‐resisting effect can be achieved in 15 min or less by steam‐pressing or by exposure to saturated steam at 100d̀C. The suggested industrial procedures are to tumble in a dryer that has provision for open steam injection or to hang in a steam‐box. Reduction of the curing time by application of an organometallic catalyst with the resin tends to cause difficulties in maintenance of the solvent machine and in garment pressing.