Continuous process for the production of blocked isocyanates
AssigneeCargill, Incorporated
InventorsK. A. Pai Panandiker, David E. Tweet
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Abstract
A method for manufacturing blocked isocyanate curing agents in which a polyisocyanate and a blocking agent for the polyisocyanate are separately and continuously metered into a reaction zone in stoichiometric proportion under reaction conditions, and in which the reaction mixture is continuously withdrawn from the reaction zone to provide a blocked isocyanate curing agent product.
Claims11
A method for manufacturing blocked isocyanate curing agents which are the reaction product of a polyfunctional isocyanate and a blocking agent for the isocyanate which is capable of splitting from the curing agent at elevated temperature to regenerate isocyanate functionality, comprising the steps of
- separately and continuously metering a polyisocyanate and a blocking agent for said polyisocyanate into a reaction zone in stoichiometric proportion to provide a reaction mixture in the reaction zone at reaction temperature, said stoichiometric proportion being based on the deficient or excess isocyanate functionality of said reaction mixture, and
- continuously withdrawing the reaction mixture from said reaction zone to provide a blocked isocyanate curing agent reaction product after maintaining said reaction mixture in the reaction zone for a time sufficient to reduce the free isocyanate functionality of the reaction product to at least a predetermined level indicating substantial completion of the blocking reaction.
Dependencies are inferred from the claim text.