Patent ID: 7164040

Claim:
A method for producing high purity glycolic acid crystals from an aqueous glycolic acid solution, which comprises the steps of: (1) providing an aqueous glycolic acid solution (A) containing monomeric glycolic acid and a glycolic acid condensation product, said aqueous glycolic acid solution (A) having the following characteristics (a), (b) and (c): (a) a water content of from 5 to 20% by weight, (b) a calculated monomeric glycolic acid weight ratio of from 0.60 to 1.00, said calculated monomeric glycolic acid weight ratio being defined as a ratio of the total weight of said monomeric glycolic acid and said glycolic acid condensation product to the weight of said aqueous solution (A), wherein the weight of said glycolic acid condensation product is expressed in terms of the weight of component monomeric glycolic acid of the glycolic acid condensation product, and (c) a monomeric glycolic acid content of from 20 to 57% by weight, (2) depositing glycolic acid crystals from said aqueous glycolic acid solution (A), and (3) recovering the deposited glycolic acid crystals from said aqueous glycolic acid solution (A).