| 摘要 |
PURPOSE:To contrive an improvement in barrier properties by a method wherein a thick walled small-diameter and cup-like vessel is manufactured through injection molding, the diameter of a belly part is expanded through mechanical plastic processing under a condition of the normal temperature by cooling a vessel slowly after that and the belly part of the vessel whose diameter has been expanded is stretched in the direction of an axial line by thinning the belly part through squeezing processing. CONSTITUTION:Polyethyleneterephthalate is adopted as synthetic resin, an initial form vessel manufactured in a thick, small-diameter and cuppy form is cooled down to the normal temperature slowly after injection molding. The diameter of a belly part is expanded by pressing a punch P, whose tip is roundish, in the vessel through an end part of an opening of the vessel within an hour after that. In this instance, as a head part of the punch P is roundish or the inside of the end of the opening is in a circular-arclike or tapered part, the punch P is pressed into the vessel smooth. Squeeze processing of the intermediate vessel, whose diameter has been expanded, is performed by making use of a mold provided with a plurality of dies D/D. The lower the dies, the dimensure become smaller, hereupon, a belly part of the intermediate vessel is thinned every time when the dies D/D of the mold are passed through the belly part. When the final die is passed through the belly part, a form of the belly part of the vessel becomes coincident with a thickness of the belly part of the vessel in a final form. |
