Ether-urethane carbodiimide

A reactive macrocyclic ether-urethane carbodiimide (MC-CDI), which is the key intermediate for synthesizing poly(amide-urethane) and poly(amide-imide-urethane), was prepared by the sequential self-repetitive reaction. A se-... 

The IPNs prepared were composed of a rubbery polyurethane and a glassy epoxy component. For the polyurethane portion, a carbodiimide-modified diphenyl-methane diisocyanate (Isonate 143L) was used with a polycaprolactone glycol (TONE polyol 0230) and a dibutyltin dilaurate catalyst (T-12). For the epoxy, a bisphenol-A epichlorohydrin (DER 330) was used with a Lewis acid catalyst system (BF -etherate). The catalysts crosslink via a ring-opening mechanism and were intentionally selected to provide minimum grafting with any of the polyurethane components. The urethane/epoxy ratio was maintained constant at 50/50. A number of fillers were included in the IPN formulations. The materials used are shown in Table I. 

The addition of carbodiimides, e.g. Staboxal PCD, which is supplied by Bayer, to poly(ester-urethanes) is one of the most effective ways to stabilize them against hydrolysis. Also the polyurethane structure can be tailored for better hydrolysis resistance through elimination or reduction of the ester groups present in the polyol. Hydrolysis resistance increases in the order of ether > polycaprolactone > polyester. Satrastab, developed by SATRA (Shoe and Allied Trades Research Association, Kettering, England), is also claimed to be an effective hydrolysis stabilizer for formulated polyurethanes in poromeric footwear materials. 

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