Polyisocyanate Composition Purification for Stable Storage Chromaticity

The patent extracts and removes the harmful residual catalyst components (quaternary ammonium base/salt impurities) from the polyisocyanate composition through purification processes. This separation eliminates the source of chromaticity instability while preserving the benefits of using quaternary ammonium catalysts during synthesis, thus resolving the contradiction between broad application range and chromaticity stability.

The patent changes the purity parameter of the polyisocyanate composition by implementing specific purification steps that reduce catalyst residue content to below detectable levels. This parameter change (from containing residual catalyst to highly purified) maintains the advantages of quaternary ammonium catalysis while eliminating the chromaticity degradation issue under high-temperature storage.

The patent employs a self-service approach where the purification process is integrated into the existing synthesis workflow using straightforward operational steps. The method utilizes the catalyst's own decomposition behavior under controlled conditions to facilitate its removal, eliminating the need for complex external treatment systems and enabling easy industrialization while maintaining high reaction efficiency.

The patent discards the residual catalyst impurities through simple filtration and washing steps after the synthesis reaction. This approach separates the high-activity synthesis phase from the purification phase, allowing efficient use of high-activity isocyanate raw materials while removing impurities through straightforward processes that are easily implementable in industrial settings.