In many customer groups, when you need to buy unsaturated resins, you must ask about the reaction time and curing time of the resin, but you don’t understand the relationship between the reaction time and the performance of the resin. To introduce the connection between the two
In general production, the progress of the reaction is controlled by measuring the acid value or viscosity of the reaction system to judge the end of the reaction. The so-called acid value is the number of milligrams of KOH consumed by 1 gram of the reaction mixture. As the reaction progresses, the hydroxyl group and the hydroxyl group continuously undergo esterification reaction, so that the concentration of the hydroxyl group in the system continues to decrease, the acid value continues to decrease, the degree of reaction continues to deepen, the molecular weight of the polyester continues to increase, and the physical properties of the unsaturated polyester resin continue to improve .
The polycondensation reaction time depends on the nature and conversion degree of the various raw material components used, and the conversion rate depends on the amount of unsaturated acid. The more unsaturated acid in the reaction mixture, the shorter the reaction time. The influence of ester performance can be seen that the shorter the reaction time, the higher the acid value of the polyester and the lower the viscosity, resulting in poor performance of the resin after curing. In actual production, the reaction time of the polyester should be controlled at 10-14 Within hours.