Patent ID: 7306738

Claim:
A method for deionizing a decomposition produced solution having a water content of not higher than 0.5 wt % resulting from decomposition of a polyester by ethylene glycol, with the weight ratio between the polyester and ethylene glycol of 1:9 to 3:7, wherein during decomposition water is distilled out of the solution and evaporated ethylene glycol is returned into the solution, the method further comprising: bringing the solution containing a decomposition product, ethylene glycol and cations and anions as impurities into contact with a cation exchanger at a temperature of not higher than 100° C. for a residence time of 5 to 60 minutes and then with an anion exchanger within 10 minutes after the contact with the cation exchanger so as to reduce contents of the cations and anions.