Polyester container having excellent heat resistance and shock resistance and method of producing the same

A method of producing a polyester container obtained by stretch-forming a preform of a thermoplastic polyester resin formed by injection forming wherein:

• the polyester container includes a bottom wall and a body wall connected to the bottom wall;
• the bottom wall consists of a central portion and a surrounding portion adjacent to and surrounding the central portion;
• the central portion of the bottom wall of the container is formed relatively thicker than a bottom wall portion surrounding the central portion, the central portion corresponding to the area of an injection gate used in the injection forming of the preform;
• the central portion of the bottom wall is substantially amorphous and has a crystallinity less than or equal to 5%;
• and
• the bottom wall portion surrounding the central portion is oriented and crystallized, the bottom wall includes a portion at a distance of 10 mm from the center of the central portion of the bottom wall having a crystallinity greater than or equal to 15%, and the bottom wall includes a portion at a distance of 6 mm from the center of the central portion of the bottom wall having a crystallinity less than or equal to 5%,
• the method comprising:
• forming a preform of a thermoplastic polyester resin having a thick central portion by injection forming;
• holding the thick portion of the preform between a stretching rod and a cooling rod;
• drawing in the axial direction by stretching the stretching rod and causing the cooling rod to move following the stretching rod and, further, blow-drawing by blowing a fluid;
• bringing an outer surface of the stretch-formed body into contact with a surface of a heating metal mold that is maintained heated by blow-drawing except the portion to where the cooling rod is contacting, in order to form the formed body into the shape of a container;
• and
• heat-setting by heating by the contact with the surface of the heating metal mold except a portion to where the cooling rod is contacting.