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Reduced solvent process for preparation of aqueous polyurethane dispersions with improved heat and solvent resistance
Reduced solvent process for preparation of aqueous polyurethane dispersions with improved heat and solvent resistance
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机译:减少溶剂的方法,用于制备水性聚氨酯分散体,具有改善的耐热性和耐溶剂性
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摘要
A process for preparing poly(urethane/urea) prepolymers and aqueous poly(urethane/urea) dispersions (PUDs) therefrom, the poly(urethane/urea) polymers having high heat resistance and good water resistance. The method employs a water soluble volatile organic solvent, such as acetone, at a level of 0.1-5%, based on final dispersion weight, a level which does not require removal for purposes of flash point considerations. The method includes the steps of reacting in the presence of a water soluble volatile organic solvent at a level corresponding to no more than 5% by weight of the final dispersion, a polyisocyanate component comprising a diisocyanate, with a polyol component to produce an isocyanate terminated polyurethane prepolymer the polyol component providing both carboxylate groups and sulfonate groups; dispersing the isocyanate terminated prepolymer in aqueous media; reacting said dispersed isocyanate terminated polyurethane prepolymer with at least one amine functional chain extender or chain terminator compound to thereby form said poly(urethane/urea) polymer; neutralizing the carboxylate and sulfonate groups of said isocyanate terminated prepolymer with an alkali hydroxide or a tertiary amine prior to, or simultaneous with, said reaction of said prepolymer and said amine functional chain extender or terminator; wherein the method is performed without a solvent distillation step.
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