Packaging material having excellent flavor retention

摘要

The present invention is a packaging material composed of a thermoplastic polyester as a constituent material. By adjusting the contents of a dibasic carboxylic acid and its oligomer derived from the polyester to 500 ppm or less, and adjusting sodium to 6 ppm or less and all alkali metals to 30 ppm or less, especially 20 ppm or less, the flavor retention of the packaging material can be markedly increased. $$