Abstract: A container molding method for reducing the amount of released acetaldehyde. The method comprises a primary blow molding step of stretch-blow-molding a preform into a primary blow-molded article; an acetaldehyde reducing step of reducing the amount of acetaldehyde released from the primary blow-molded article; and a final blow molding step of stretch-blow-molding the primary blow-molded article having a reduced amount of acetaldehyde into a final container. The primary blow molding step molds the primary blow-molded article which is larger in size than the final container and which has an average wall-thickness of a stretched barrel portion equal to or less than 0.3 mm, that is smaller than the average wall-thickness of a barrel portion of the final container. The acetaldehyde reducing step heats the thin-walled barrel portion of the primary blow-molded article at a high temperature for a relatively short time.

Abstract: A heat-resistant container forming method includes a step of thermally shrinking a primary blow molded article in a heating furnace before secondary blow molding the primary blow molded article into a final product or container. Into the furnace, hot air which flows along the longitudinal direction of the first blow molded article and whose temperature enough to facilitate crystallization of the primary blow molded article. The primary blow molded article is thermally shrunk by exposing the entire circumferential surface of a barrel of the primary blow article to the hot air and by blowing the hot air longitudinally along the primary blow molded article to heat the barrel circumferentially uniformly. Since hot air touches the barrel as flowing longitudinally thereof, it is possible to increase the heat conductivity of boundary film of the primary blow molded article, without increasing the hot air temperature too high, so that temperature rise of the primary blow molded article is facilitated.

Abstract: A heat-resistant container forming method includes a step of thermally shrinking a primary blow molded article in a heating furnace before secondary blow molding the primary blow molded article into a final product or container. Into the furnace, hot air which flows along the longitudinal direction of the first blow molded article and whose temperature enough to facilitate crystallization of the primary blow molded article. The primary blow molded article is thermally shrunk by exposing the entire circumferential surface of a barrel of the primary blow article to the hot air and by blowing the hot air longitudinally along the primary blow molded article to heat the barrel circumferentially uniformly. Since hot air touches the barrel as flowing longitudinally thereof, it is possible to increase the heat conductivity of boundary film of the primary blow molded article, without increasing the hot air temperature too high, so that temperature rise of the primary blow molded article is facilitated.

Abstract: A multi-layer forming nozzle includes a valve member which can open and close a flow passage for molten resin which forms an intermediate layer of a multi-layer molded product by injection molding. The valve member is operated in response to resin pressure differentials at the front and back of the valve member to accurately switch from a multi-layer operation to a single layer operation and vice versa. A three-layer nozzle in accordance with the invention has a nozzle body provided interiorly with a first resin path, a second resin path and a third resin path in the form of a concentric circle bending to the same injection opening. The valve member is located either in a mouth portion of the third resin path in the central portion positioned internally of a mouth portion of the second resin path or a mouth portion of the second resin path in the intermediate portion positioned internally of the first resin path.

Abstract: A multi-layer forming nozzle includes a valve member which can open and close a flow passage of molten resin which forms an intermediate layer of a multi-layer molded product by injection molding. The valve member is operated in response to resin pressure differentials at the front and back of the valve member to accurately switch from a multi-layer operation to a single layer operation and vice versa. A three-layer nozzle in accordance with the invention has a nozzle body provided interiorly with a first resin path, a second resin path and a third resin path in the form of a concentric circle bending to the same injection opening. The valve member is located either in a mouth portion of the third resin path in the central portion positioned internally of a mouth portion of the second resin path or a mouth portion of the second resin path in the intermediate portion positioned internally of the first resin path.