Method for preparing low-chromatic number isocyanate and isocyanate prepared by same

Abstract

The invention relates to a method for preparing low-chromatic number isocyanate containing a carbodiimide and / or uretonimine group capable of being stored in a liquid state and the isocyanate containing the carbodiimide and / or uretonimine group capable of being stored in the liquid state prepared by the method. The method comprises the following steps of: a) reacting an isocyanate group of the raw material isocyanate under the action of a cyclopentene phosphine catalyst to obtain isocyanate reaction liquid partially catalyzed by carbodiimide; and b) adding an anhydride terminating agent into the reaction liquid obtained from the step a) and terminate carbodiimide reaction. The liquid isocyanate prepared by the method has the advantages of low chromatic number and good storage stability.

Description

technical field [0001] The invention relates to a preparation method of a liquid isocyanate mixture, which contains carbodiimide (CDI) and / or uretonimine (UTI) groups, has low color number and good storage stability. Background technique [0002] Isocyanate can convert isocyanate group (NCO) into CDI group by partial carbodiimidization, and CDI group is added with NCO group to form UTI group. This method can provide storage-stable liquid isocyanate, which is convenient for storage and transportation , and no chemicals are required during use. [0003] Isocyanate mixtures containing CDI and / or UTI groups can be prepared simply by using efficient catalysts of the phospholine class, in particular of the phospholine oxide class. The preparation method can refer to US-A-2853473, US-A-6120699 and EP-A-515933. [0004] Phospholene catalysts with high catalytic activity, especially phospholene oxide catalysts, can catalyze the carbodiimidization reaction at a relatively mild tempe...

AI Technical Summary

Problems solved by technology

[0009] Acids are commonly used terminators, including hydrochloric acid, adipic acid, phthalic acid, trifluoromethanesulfonic acid, etc. During the reaction process, the -OH or active hydrogen atom of the acid substance will react or complex with the NCO group in the isocyanate to a certain extent, so that the termination effect of the acid terminator is significantly reduced, resulting in the presence of CDI and / or UTI groups The color number of the isocyanate is poor, and the prepared isocyanate containing CDI and / or UTI groups has poor stability during storage, and the viscosity gradually increases

[0010] Existing methods for preparing liquid isocyanates containing CDI and / or UTI groups are difficult to overcome the above defects

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