Dicarboxylic acid is a plant derived carbon chain length of 21 synthetic dibasic acid, is a set of lubrication, emulsification, corrosion inhibition, coupling and hard water resistance in one of the multi-functional additives, to improve the life of the working fluid is helpful, easy to adjust the formula. POLYEM C21 significantly improves resistance to hard water and enhances cleaning capacity. Neutralization with amines provides additional rust protection and emulsification capabilities. In the total synthesis system, the polyether can be dissolved and the turbidity point of the solution can be increased.