| 摘要 |
PROBLEM TO BE SOLVED: To provide polyethylene terephthalate having a high compatibilizing speed, which can give a resin composition excellent in heat resistance, in gas barrier properties and particularly in transparency when blended with polyethylene naphthalene dicarboxylate at a relatively low temperature. SOLUTION: Polyethylene terephthalate, which has an intrinsic viscosity of 0.7-1.0, a carboxylic end group concentration of 30 equivalents/ton or less, a crystallization degree of 60% or less and a melting point of 250 deg.C or below and contains elements antimony and/or germanium, the total content of these elements being 40-250 ppm, of which the solubilizing speed K, when blended with polyethylene naphthalene dicarboxylate having a carboxylic end group concentration of 40 equivalents/ton or less and a total end group number of 95 equivalents/ton or more in an amount 1/9 time as much as that of the polyethylene terephthalate, satisfies the equation: K>=1.644×103×exp(-4.678×103/T) (wherein T is a melting temperature (absolute) when the polyethylene terephthalate is blended with the polyethylene naphthalene dicarboxylate).
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