PROCESS FOR THE PREPARATION OF SEMI-RIGID POLYURETHANE FOAM HAVING EXCEPTIONAL SHOCK-ABSORBING ERTIES AND VEHICLE BUMPERS THEREOF

摘要

OF THE DISCLOSlmE A ___ _ _ _ A process ls provlded for produclng seml-rlgid polyurethane ioams havlng exceptional sboclc-abYorblng propert~es, even after repeated compresslon, prepared ~y the reaction of a polylsocyanate; a polyether polyol haylng a molecubr we~ght wlthln the range trom about 2, 000 to about 10, OOO;from about 1 ~o about ~i~ by welght of water per part by we~ht of polyetber polyol; from about 1 to about 6~c by ~velght of ~urea and/or thloures. per part by welght of polyether polyol; and a cross-1lnklng compour.d haYlng at least three actlve hydrogen atoms per molecule that are reactlve wlth lsocyanate grou~ and havlng a molecular we~ght below about 1000 ln an amount from about 5 to about 25g~ by welght per part by weight of polyether polyol; the amount of polylsocyanate belng selected to give an lsocyanate index wlthln the range from about 0. 7 to about 1. ~. The process provldes polyurethane foams that have a cellular structure that remalns un~maged under compresslon as high as 60~ at temperatures wlthln the range from about ~ 60.degree.C to about -40~C, and the consequent deformatlon Is 1ess than 1~ even after ten compresslons of at least 50~ In rapid succession. Accordingly, tlle lnYention iurther pro~rides vehlcle bumpers haYing an impact-r~celvlng layer of thls polyurethane foam, and that meet th~ requlrements of FM~SS 215.