A preform made from two different materials that do not bond together by a bi-injection process, using the same mold, is presented. An outer layer of the preform can be first made, then an inner layer molded through a center hole in a bottom of the outer layer, and the two layers connected. Inner/outer preform materials can be different, such as PET/polyolefin or polyamide, or the same, such as PET/PET. To prevent mutual bonding during molding of the second layer, a non-stick coating may be sprayed onto a surface portion of the first layer prior to molding the second. In embodiments, manufacturing order can be either outer/inner, or inner/outer, and the non-stick coating sprayed on the inside/outside of the layer first molded.

A manufacturing method includes an injection molding process of injection-molding a preform having a two-layer structure including an outer layer preform and an inner layer preform, and a blow molding process of blow molding the preform to mold a delamination container made of resin. The injection molding process includes an outer layer molding process of filling an outer layer injection mold with PET (outer layer resin material) to mold the outer layer preform and molding a thin film portion in a part of the outer layer preform, and an inner layer molding process of injecting PP (inner layer resin material) toward the thin film portion to break the thin film portion and filling an inner layer injection mold with PP having a temperature lower than a melting point of PET via the broken thin film portion to mold the inner layer preform.

A cooling mold for cooling a resin preform that has a gate portion protruding outward from a center of a bottom portion, in which an accommodating space that accommodates the preform is formed in the cooling mold, a bottom region facing the bottom portion of the preform in the accommodating space has a shape following the bottom portion of the preform, and an air sucking hole for sucking air is formed in the bottom region at a position shifted from the center of the bottom portion of the preform. In the accommodating space, a region facing a body portion of the perform and a bottom region facing the bottom portion of the perform are formed as a single member.

A blow molding mold in which a holding mechanism is independently provided to a bottom mold and is configured to be capable of gripping a protruding portion provided to a bottom portion of a preform independently of a gate portion, and a rotation mechanism is configured to be capable of rotating the bottom mold, relative to a neck portion of the preform which is in a stationary state held by neck molds, in a state where the protruding portion is gripped by the holding mechanism.

A preform configured to be blow-molded into a container. The preform includes a first layer and a second layer. The first layer is an active oxygen scavenger layer including an oxygen scavenger, a catalyst, and a first material having up to 25% recycled polymer. The second layer includes a second material having at least 25% recycled polymer.

A manufacturing method of a resin container includes: a first injection molding process for injection-molding a first layer of a preform by using a first resin material, the preform having a bottomed cylindrical shape and including a groove that extends in an axis direction; a second injection molding process for injecting a second resin material into the groove of the first layer, the second resin material having a color that is different from a color of the first resin material, and laminating a second layer on an outer peripheral side or an inner peripheral side of the first layer; and a blow-molding process for blow-molding a preform that includes multiple layers and has been obtained in the second injection molding process in a state where residual heat at a time of injection molding is contained, and manufacturing the resin container having a vertical-striped color pattern formed by using the second layer.