POLYURETHANE BEND STIFFENER

摘要

A bend stiffener comprises a (i) a flexible polymeric sleeve having an axial bore for receiving an elongated flexible member and (ii) attachment means for attaching the sleeve to a support. At least a portion of the flexible polymeric sleeve is a polyurethane elastomer produced in a reaction of an isocyanate-terminated prepolymer and a curing agent at an isocyanate index of 90 to 120. The isocyanate-terminated prepolymer has an isocyanate content of 7 to 15% by weight and is a reaction product of at least one aromatic polyisocyanate and at least one polyether polyol having a hydroxyl equivalent weight of 350 to 2000 and a nominal functionality of 2 to 2.3. The curing agent is one or more chain extenders having an equivalent weight per isocyanate-reactive group of up to 125 or a mixture of one or more such chain extenders and one or more polyether polyols having a hydroxyl equivalent weight of 350 to 2000 and a nominal functionality of 2 to 2.3. The hard segment content of the polyurethane elastomer is from 40 to 60% by weight.