| 摘要 |
<p>PURPOSE:To achieve a drastic improvement in the gas barrier property by producing a bottle from a polyethylene naphthalate resin in such a way that the distribution curves of the X-ray interference strength at a plurality of spots on the circumferential surface in the middle of the drumlike part have specific maximum values. CONSTITUTION:A bottle 1 consists of a mouth part 2, a shoulderlike part 3, a drumlike part 4, a peripheral bottom 5, and a bottom 6. It is observed that, with a probability of not less than 80% at the lowest estimate, the distribution curves of the X-ray interference strength at a plurality of spots on the circumferential surface in the middle of the drumlike part 4 have maximum values in the beta-angle ranges of 0 deg.+ or -20 deg. and 90 deg.+ or -20 deg.. To make such a bottle 1, first a prefoam is obtained from polyethylene naphthalate resin; the prefoam is made in a short form, with the diameter also reduced as occasion demands; the prefoam is so highly stretched as to bring the draw index to 130cm or more, and then subjected to blow molding. By subjecting the resulting prefoam to biaxial stretching and to molding by a molding machine a bottle 1 having a drastically improved gas-barrier property to oxygen or carbon dioxide is obtainable. The product is excellent also in heat resistance, transparency, and mechanical strength.</p> |
