Recently, polyurethane latent curing agents, a core additive in the polyurethane material field, have become the focus of the industry due to their unique "latent" characteristics and performance advantages. This additive, prepared through the dehydration condensation of aldehydes/ketones and amines, is revolutionizing the storage stability, construction controllability, and final performance of polyurethane products through precise formula design and technological innovation.
    The core of latent curing agent synthesis lies in the dehydration condensation reaction between aldehydes/ketones and amines. By controlling the moisture in the system to promote the forward reaction, imine or oxazolidine and other characteristic structures are formed. Its "latent" mechanism is based on reversible hydrolysis when exposed to water, releasing amine substances to crosslink with polyurethane prepolymers, realizing a controllable process of "first combination, then decomposition, and subsequent reaction", which significantly extends the material storage period and construction window.
    Currently, mainstream products are divided into aldimine/ketimine types and oxazolidine types. The former releases highly active primary amines upon hydrolysis with fast curing speed, while the latter releases mild secondary amines, facilitating the control of the curing process. Depending on the type of amine raw materials, aliphatic products offer excellent yellowing resistance, while aromatic products exhibit higher reactivity and outstanding heat resistance. By adjusting the number of functional groups, difunctional products can improve material flexibility, and multifunctional products enhance rigidity, meeting the needs of different application scenarios. In practical applications, composite matching has become a technical trend. The combination of aldimine/ketimine and oxazolidine can balance curing speed and product quality, while the compounding of difunctional and multifunctional products can precisely regulate the mechanical properties of materials. In addition, the synergistic use with latent substances such as phenols further expands the application space of products in special processes.
    As a key link in the upgrading of polyurethane materials, the technological innovation of latent curing agents is driving the performance optimization of products in various fields such as automotive, construction, and electronics. In the future, with the continuous breakthroughs in raw material combinations and formula design, their application scenarios will be further expanded.

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