| 摘要 |
<p>PURPOSE:To obtain a polyester container having high orientation crystallization and being reduced in its distortion while precluding a deflection of the wall thickness by specifying the temperature within a hollow mold, and the temperature of preform, and the high speed drawing condition. CONSTITUTION:The temperature within a hollow mold is kept at a temperature of 125 deg.C or higher, the preform is kept at such temperature that the natural drawing ratio ND specified by formula I becomes 1.6 or above, and high speed drawing is effected in order that the rate of a peripheral thickness fluctuation in a maximum drawing part in the peripheral direction becomes 50% or below. However, L0 in the formula I shows a rate of distortion in the yield point as a material of JIS K 7113 consisting of thermoplastic polyester undergoes a tensile test at a predetermined temperature and at a tensile speed of 500nm/min. Also, L shows a rate of distortion as the material reaches the same stress as the yield point stress after passing the yield point in the tensile test. If molded in the condition, the wall-deflection is prevented during the period of blow drawing molding, thereby enhancing the orientation crystallization and reducing the distortion.</p> |
