| 摘要 |
PURPOSE:To obtain the bottle made of PET, which has large capacity size and plural projections for self-supporting at the bottoms for by a method wherein a temperature at the time of blow-molding is adjusted to 95-104 deg.C, the back pressure of a blowing cavity is decreased and the PET is blown and molded at the high speed of 0.1sec or lower. CONSTITUTION:A close-end parison 7 injected, which is made of PET, is released from a mold at a temperature where the temperature in thickness is high and the shape is kept, temperature difference between inner and outer surfaces in the same flat section of the close-end parison and a center of the thickness is equalized, and the temperature of the parison at the time of blow- molding is adjusted to 95-104 deg.C. The close-end parison is drawn and expanded at the high speed of 0.1sec or lower while the escape of air is increased to 10 times or more of conventional bottles so that the back pressure of the cavity of a blowing die is decreased remarkably. Accordingly, the close-end, self-supporting bottle PET with bottom projections 5, the degree of orientation and crystallinity thereof are enlarged and which is excellent in gas barrier property, is obtained. The degree of orientation of a face is 130X10<-3> or higher. |
