MOCA (methylene bis-ortho-chloroaniline) is the curative-of-choice for waterproof roof coating in Japan. These coatings are typically hand applied and require long pot-lives. Basic formulations use 3-6% NCO TDI prepolymers and are highly plasticized. However, due to the carcinogenic nature of MOCA, many customers want to move away from MOCA. The major technical challenge is to determine a curative system that gives a prolonged pot-life yet a relatively short tack-free time, at the same time delivers appropriate physical properties. Presented here are our efforts to develop a curative formulation to be used in the Japanese market as a MOCA replacement.
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