Hollow injection molded article made of plastic material, esp. preform for blow molding a container, with a wall (17) extending along axis (I), which is composed of a layer of variable thickness (), being remarkable in that longitudinal ribs are provided in said axis direction, wherein the wall has a tooth profile of periodic nature varying periodically between a minimum and a maximum threshold value (m, resp. M) which is determined by a typical injection molding length (Ls) for said plastic material and/or characteristic ratio (max/min). A method of manufacturing thereof (10) by injection molding comprising forming inner and outer preforms (11, 12) with formation of an integrated composite preform (10), and apparatus for this purpose.

To solve a problem associated with formation of a transparent window portion in a biaxially stretch blow molded container by a nozzle structure of an injection molding apparatus, provided is a biaxially stretch blow molded container that is formed with a clearly transparent window portion in a longitudinal strip shape by effectively preventing mixture and cut-in of a colored resin to the window portion. In a predetermined range extending from an upstream end to a predetermined downstream position of a flow path including a cylindrical flow path and a reduced-diameter flow path formed in a nozzle portion, a pair of guiding ribs in the form of longitudinal ridges is arranged in line to partition the flow path in a circumferential direction, and a longitudinal groove flow path is formed between the pair of guiding ribs. A molten B resin is supplied to the longitudinal groove flow path, and a molten A resin is supplied to the cylindrical flow path excluding the longitudinal groove flow path. Thus, the longitudinal strip-shaped flow path of the B resin interrupts the cylindrical flow path of the A resin in the circumferential direction.

A preform-molding device has a nozzle section including three cylindrical layer-forming flow channels, which include an inner flow channel and an outer flow channel for forming the substrate layers of the main resin, and a middle flow channel for forming the intermediate layer, and also includes a predetermined number of vertical blocking rib pieces disposed at a downstream end of the middle flow channel, in parallel in the circumferential direction, so that the intermediate layer would be segmented in the circumferential direction into a predetermined number of vertically running streams, wherein flow behavior of the intermediate-layer resin flowing through the middle flow channel is adjusted by positioning the vertical blocking rib pieces in the circumferential direction so as to minimize a difference in height between a maximum height point and a minimum height point that appear in a leading edge of the intermediate layer of the preform.

A molded article suitable for subsequent blow-molding into a final-shaped container. The article includes a neck portion; a gate portion; and a body portion extending between the neck portion and the gate portion, at least a majority of the body portion having an overall shape which is symmetric about a body axis extending longitudinally through a center of the body portion. The body portion includes an inner exterior layer and an outer exterior layer of a first polymeric material; and a core layer of a second polymeric material disposed between the inner exterior layer and the outer exterior layer. A radial thickness or a material of the core layer is selectively varied to govern non-uniform blow molding of the molded article into the final-shaped container.

A method of injection molding a test tube-shaped preform for biaxial stretch blow molding includes supplying a major material resin from outer and inner flow paths to a combined flow path for a predetermined time and rate. For a period of time within a range of the predetermined time period during which the major material resin is supplied, the intermediate layer resin is simultaneously supplied from the middle flow path to the combined flow path at a second predetermined supplying rate. A columnar laminated molten resin is injected into a cavity of a metal mold connected to a tip of the nozzle through a gate to fill the cavity, the columnar laminated molten resin being composed of the major material resin and the intermediate layer resin formed in the major material resin in a laminated manner that are combined into a columnar shape at the combined flow path.

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.