Curing of Polyurethane Adhesives: Principles, Types and Key Points
2026,03,16
The bonding strength of polyurethane adhesives is achieved through the curing reaction. Unlike the physical evaporation and drying of ordinary adhesives, PU adhesives mostly undergo chemical reaction curing. Once the cross-linking process is completed, the bonding force and durability will significantly improve, which is the core advantage that makes it suitable for various scenarios.
1.The mainstream methods of solidification have their respective applicable scenarios.
(1)Humidity curing is the mainstream method for single-component PU adhesives. It relies on the water vapor in the air to undergo cross-linking reactions, and can cure at room temperature. There is no need for mixing during construction, and it is suitable for manual operation and simple working conditions. The curing speed is greatly affected by humidity and temperature.
(2)Heating curing is mainly used for thermosetting types and some two-component adhesives. By heating, the reaction of the base groups is triggered, resulting in a fast curing speed and stable positioning. This can significantly shorten the construction period and is suitable for automated production lines and batch processing scenarios.
(3)The two-component curing process is triggered by mixing the main agent and the curing agent in a certain proportion. This leads to a more thorough cross-linking, resulting in high bonding strength and outstanding weather resistance. It is commonly used in structural bonding scenarios such as those in automobiles and new energy fields. The accuracy of the ratio directly determines the curing effect.
2. Matters to be noted during the solidification process
Low temperature and insufficient humidity will slow down the curing process and even lead to incomplete curing. Oil stains and dust on the substrate surface can also damage the cross-linking structure. During the construction process, it is necessary to control the temperature and humidity and perform proper surface treatment to ensure that the PU adhesive can perform at its best and avoid problems such as delamination and insufficient strength.
