Method of molding a heat-resistant container

A method of molding a heat-resistant container comprising:

• a primary blow molding step in which a preform of a synthetic resin is molded into a primary blow-molded article in a primary blow mold;
• a step of transferring said primary blow molded article from said primary mold to a heat treatment mold;
• a primary heat treatment step in which said primary blow-molded article is held in the heat treatment mold and heat treated;
• a secondary heat treatment step in which a shrunken intermediate molded article removed from said heat treatment mold is subjected to heat treatment outside said heat treatment mold;
• and
• a secondary blow molding step in which said intermediate molded article having been subjected to heat treatment outside said heat treatment mold is blow-molded into a final molded product in a final blow mold;
• wherein in said primary blow molding step the longitudinal length of said primary blow-molded article is formed to be longer than the longitudinal length of said final molded product;
• wherein the longitudinal and lateral dimensions of said shrunken intermediate molded article removed from said heat treatment mold after said primary heat treatment step are slightly less than the longitudinal and lateral dimensions of said final molded product;
• wherein in said secondary heat treatment step, heat treatment is carried out with almost no shrinkage of said intermediate molded article due to strain release from the primary heat treatment step,
• and wherein said primary heat treatment step includes a step in which said primary blow-molded article disposed within said heat treatment mold is pressurized and subjected to heat treatment, and wherein there is a step in which after said primary heat treatment is completed said primary blow-molded article is evacuated thereby producing the shrunken intermediate article.

A method of molding a heat-resistant container comprising:

• a primary blow molding step in which a preform of a synthetic resin is blow-molded into a primary blow-molded article;
• a primary heat treatment step in which said primary blow-molded article is held in a heated mold and heat treated;
• a secondary heat treatment step in which a shrunken intermediate molded article removed from said mold is subjected to heat treatment outside said mold;
• a secondary blow molding step in which said intermediate molded article having been subjected to heat treatment outside said mold is blow-molded into a final molded product in a final blow mold;
• wherein said intermediate molded article includes a neck portion with an opening, a tubular body portion, a bottom portion sealing one end of said body portion, a shoulder portion joining said neck portion and said body portion, and a heel portion joining said body portion and said bottom portion;
• and
• wherein in said secondary heat treatment step, heat treatment is carried out with the quantity of heat supplied to each of said shoulder and said heel portions being greater than the quantity of heat supplied to said body portion.

A method of molding a heat-resistant container comprising:

• a primary blow molding step in which a polyethylene terephthalate preform is blow-molded in a primary mold into a primary blow-molded article with a longitudinal axis which is longer than a longitudinal axis of a final molded product;
• a step of transferring said primary blow molded article from said primary mold to a heat treatment mold;
• a primary heat treatment step in which said primary blow-molded article is held in the heat treatment mold, the interior of said primary blow-molded article is pressurized, said primary blow-molded article is held in intimate contact with the inner surface of said mold for a period of 2 to 10 seconds, and is subjected to heat treatment in the range of 150 to 220.degree. C. being a temperature to promote crystallization of said polyethylene terephthalate, whereby strain occurring in said primary blow-molded article is eliminated thereby producing a shrunken intermediate article;
• a secondary heat treatment step in which said intermediate molded article, removed from said heat treatment mold, and shrunken according to the residual strain of said primary blow-molded article with a body diameter smaller than the body diameter of said final molded product, is subjected to heat treatment by radiant heat of an infrared heater at a temperature to promote crystallization of said polyethylene terephthalate,
• a secondary blow molding step in which said intermediate molded article having been subjected to heat treatment outside said heated mold is blow-molded into said final molded product in a final blow mold heated to at least the temperature required for heat resistance of said final molded product,
• and wherein said primary heat treatment step includes a step in which said primary blow-molded article disposed within said heat treatment mold is pressurized and subjected to heat treatment, and wherein there is a step in which after said primary heat treatment is completed said primary blow-molded article is evacuated thereby producing the shrunken intermediate article.