Solvent-based laminating adhesives are mainly classified into three types based on the ratio of the main agent to the curing agent: forward adhesive, reverse adhesive, and polyether adhesive.
In forward adhesives, the main agent is capped with hydroxyl groups, and the ratio of the main agent to the curing agent is generally (5~10):1. The storage time for forward adhesives is generally >12 hours, and the reaction rate is relatively slow at the same temperature.
In reverse adhesives, the main agent is capped with isocyanate groups, and the ratio of the main agent to the curing agent is generally (20~50):1. The storage time for reverse adhesives is generally <6 hours, and the reaction rate is relatively fast at the same temperature.
The ratio of the main agent to the curing agent in polyether adhesives is generally 20:20. The reaction rate of polyether adhesives is comparable to that of reverse adhesives.
