A coating type flame retardant was made by mixing a small amount of starch based on a soufa 23% aqueous solution.
It is applied to rigid urethane foam and its flame retardancy is confirmed.
As a result, it was able to withstand the 5-minute combustion test.
At the same time as the flame hit the rigid urethane foam surface, a foam layer was formed, and the starch carbonized to form a carbonized layer, forming a double film.
It is considered that a certain degree of performance can be imparted to the rigid urethane foam.