PURINATE - Blocked Polyurethane Systems
Blocked Polyurethane Systems
Prepolymer resins have pot life problems due to their reactive ends and pot life problems during application. Stoving Polyurethane Resins are the resin types that are frequently used in systems.
This system is based on closing the isocyanate ends of prepolymer resins with the help of blocking agents. It can be converted into any type of prepolymer block system with different blocking techniques.
Depending on the blocking agent used, when the blocked-prepolymer reaches certain temperatures, the blocking agent separates from the prepolymer structure and isocyanate ends appear. Then, these isocyanates react with each other or with the necessary groups, and all ends of the system are closed without opening. In this way, the resin dries. There are many different blocking agents, and each performs at different deblocking temperatures. These temperature values are approximately in the range of 100 - 160 ºC.
The bonds between the isocyanate and the blocking agents at the ends of the prepolymer structure are weak. In this way, they are easily separated at certain temperatures. However, the bonds formed later by the opened isocyanates are strong and it is very difficult to separate again.
These systems are designed as one component and there is no deterioration in their structure as long as they do not reach the required temperatures. When it reaches the required temperatures, its structure changes with an irreversible reaction.