METHOD OF ELIMINATING GATE MARK ON BOTTOM WALL OF BIAXIALLY STRETCHED TRANSPARENT BOTTLE MADE OF SATURATED POLYESTER

摘要

PURPOSE:To enhance the merchandizing value of a bottle with a devised pattern by forming a relief pattern on the outer surface of the bottom wall of a bottle including a gate mark with a projection or indentation on the inner surface of a cavity so that the edge line surrounding the gate mark becomes less visible. CONSTITUTION:A cold parison having a gate mark on the outer surface of the bottom is stretched and expanded in a blow molding metallic die in which a multiple relief pattern 5 is formed on a surface for forming the bottom wall of a bottle in a cavity of the metallic die. A pattern identical to the pattern 5 but reverse in the arrangement of the projection and indentation is formed on the outer surface of the bottle bottom wall 9 in such a manner that the edge line 4 surrounding the gate mark is made as a part of the pattern 5 or included in the pattern whereby the edge is less visible.