Heat resistant container molding method

A method of molding a heat resistant container, the heat resistant container including a body part, a bottom part formed at a first axial end of the heat resistant container, and a heel part connecting the bottom part to the body part, the bottom part having a raised part extending inwardly toward a second axial end of the heat resistant container, the raised part having a central part formed in a center of the raised part and an edge part surrounding said central part, the edge part connecting the central part to the heel part, the method comprising the steps of:

• (a) primary blow molding an injection molded preform into a primary blow molded article in a primary blow cavity mold, the primary blow molded article being axially longer than the heat resistant container, the primary blow molded article having a less-stretched region;
• (b) heat shrinking the primary blow molded article into a heat shrunk primary blow molded article, an axial length of the heat shrunk primary blow molded article being greater than an axial length of the heat resistant container, the axial length of the heat shrunk primary blow molded article being measured from a top of the heat shrunk primary blow molded article to a bottom center of the heat shrunk primary blow molded article, the axial length of the heat resistant container being measured from a top of the heat resistant container to a peak of the raised part of the heat resistant container;
• (c) inwardly forming the central part of the raised part in said less-stretched region in a secondary blow cavity mold by moving a bottom mold in a vertical direction, the central part contacting the bottom mold without an area corresponding to the edge part of the raised part contacting the bottom mold when the bottom mold stops moving in the vertical direction;
• and
• (d) after said forming step, secondary blow molding the heat shrunk primary blow molded article into the heat resistant container within the secondary blow cavity mold, wherein said heel part and said edge part each have a desired wall thickness thinner than a wall thickness of the central part of the raised part, and the less-stretched region becomes limited to the central part of the raised part, the less-stretched region having a lower stretch ratio than a stretch ratio of the body part of the heat resistant container.