AH 405

Polyester polyol is formed by condensation of dicarboxy acid and dibasic alcohol. Alcohol would not only be used for long ester chain, but also be contained in the tail group(-OH). Therefore, alcohol should be excess 5~20% for condensation reaction. And the ration of polyacid and polyol should be determined by the desired final molecular weight or equivalent. Polyester polyols contain many ester group in structure, which leads to better product properties than polyether polyol, such as rigidity, thermal stability, permeability, oil resistance and adhesion.