| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for manufacturing a polyester resin wherein while recovered polyethylene terephthalate is left melted, a necessary amount of an organic compound of tin is added thereto and uniformly dissolved, to which a desired polyhydric alcohol is added within a short time, thereby permitting the decomposition of the glycol to be performed within a short time without causing gelation as a whole. SOLUTION: R-PET from a PET bottle is melted at 260 deg.C or over, under which a tin compound is added to and uniformly dissolved therein, followed by further addition of a glycol in about 20 to 30 minutes. While keeping the temperature for about 15 to 20 minutes to make a uniform solution, a necessary amount of anα,β-unsaturated polybasic acid or its acid anhydride is added for polycondensation so as to prepare a polyester. Moreover, a required monomer is dissolved to obtain a polyester resin. The organic compound of tin is dibutyltin dilaurate or the like. The polyhydric alcohol is dipropylene glycol or the like when the monomer used in combination is styrene, or ethylene glycol or the like when using an acrylic monomer such as diallyl phthalate or the like.
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