Iron(III) Complex Catalysts for Selective Polyurethane Curing

The patent changes the chemical parameters of the catalyst by using iron(III) complex compounds with specific ligands (β-diketonates, carboxylates, or alkoxides) instead of conventional amine or tin catalysts. This parameter change provides high selectivity for the urethanization reaction while maintaining fast curing speed, thereby eliminating bubble formation caused by non-selective catalysis.

The patent modifies the physical parameters of the iron(III) complex by changing the ligand structure from acetylacetonate to compounds with longer alkyl chains (such as 2,4-pentanedionate with hexyl groups or 6,6,7,7,8,8,8-heptafluoro-2,4-pentanedionate). This parameter change transforms the catalyst into a liquid at room temperature or significantly improves its solubility in polyol compositions, eliminating the need for organic solvents or high curing temperatures while maintaining high catalytic activity.

The patent changes the chemical parameter of the ligand from carboxylate to β-diketonate or alkoxide groups, which form more stable complexes with iron(III) that are resistant to hydrolysis. This parameter change maintains good solubility in polyol compositions while providing excellent hydrolytic stability, allowing the catalyst to remain active during long-term storage without significant deactivation.

The patent utilizes phase transition by designing iron(III) complex compounds that are liquids at room temperature or have very low melting points. This phase change from solid to liquid state eliminates the need for organic solvents to dissolve the catalyst and enables easy incorporation into polyol compositions at room temperature, while maintaining high catalytic potential for fast curing.