| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a process capable of recovering an aromatic dicarboxylic acid with a high yield and for a short time, by hydrolyzing a polyester containing a very fine inorganic solid having a specific primary particle dia. which is a dehydrated condensate of an aromatic dicarboxylic acid and a polyhydric alcohol by using a specified critical water, then separating and removing the inorganic solid under a specified condition, and then recovering the aromatic dicarboxylic acid. SOLUTION: A recovering process comprises steps of hydrolyzing a polyester, pref. a poly(ethylene terephthalate), containing a very fine inorganic solid (e.g. catalyst or pigment) having a primary particle dia. of 1 μm or less, which is hydrated condensate of an aromatic dicarboxylic acid and a polyhydric alcohol by using a liquid, subcritical or supercritical water in a wt. ratio of 2-20 fold thereto, under a condition of a temp. from higher than 300 deg.C to lower than 500 deg.C, a press. 9 to 50 MPa and a reaction time 1 to 60 min, then of separating and removing precisely the inorganic solid at a temp. from higher than 300 deg.C to lower than 500 deg.C in just the state which a produced aromatic dicarboxylic acid has been dissolved in the subcritical or supercritical water, and then of depositing the aromatic dicarboxylic acid by lowering the temp. and the press., thus recovering it.</p> |
