Synthetic resin container with window, preform, and method of injection molding preform

Abstract

A synthetic resin container or bottle with a window obtained by subjecting a test tube-shaped preform made by injection molding to biaxial stretch blow molding is provided. The container includes a transparent base layer; a circumferential wall formed of the transparent base layer; and a light-blocking or opaque intermediate layer formed in the base layer in a laminated manner to cover an area of a predetermined height of the circumferential wall. The intermediate layer is formed in a laminated manner over an area covering an entire circumference of the circumferential wall excluding a non-laminated section, where the intermediate layer is not formed, that extends in a shape of a longitudinal strip along the central axis direction of the container on the circumferential wall of the container. The non-laminated section serves as a window section.

1 . A test tube-shaped preform for biaxial stretch blow molding made by injection molding, the preform comprising:
 a transparent base layer;   a circumferential wall formed of the transparent base layer; and   a light-blocking or opaque intermediate layer formed in the base layer in a laminated manner over an area of a predetermined height of the circumferential wall,   wherein the intermediate layer is formed in a laminated manner over an area covering an entire circumference of the circumferential wall excluding a non-laminated section, where the intermediate layer is not formed, that extends in a shape of a longitudinal strip along a central axis direction on the circumferential wall of the preform.   
     
     
         2 . The preform according to  claim 1 , wherein the intermediate layer is formed in a laminated manner to cover a range of substantially a total height. 
     
     
         3 . The preform according to  claim 1 , wherein the intermediate layer is formed in a laminated manner over an entire area near a bottom that at least includes a bottom wall. 
     
     
         4 . A synthetic resin container with a window in a form of a bottle obtained by subjecting a test tube-shaped preform being a precursor made by injection molding to biaxial stretch blow molding, the container comprising:
 a transparent base layer;   a circumferential wall formed of the transparent base layer; and   a light-blocking or opaque intermediate layer formed in the base layer in a laminated manner to cover an area of a predetermined height of the circumferential wall,   wherein the intermediate layer is formed in a laminated manner over an area covering an entire circumference of the circumferential wall excluding a non-laminated section, where the intermediate layer is not formed, that extends in a shape of a longitudinal strip along a central axis direction of the container on the circumferential wall of the container, and   the non-laminated section serves as a window section.   
     
     
         5 . The synthetic resin container with a window according to  claim 4 , wherein the intermediate layer is formed in a laminated manner to cover a range of substantially a total height. 
     
     
         6 . The synthetic resin container with a window according to  claim 4 , wherein the intermediate layer is formed in a laminated manner over an entire area near a bottom that at least includes a bottom wall. 
     
     
         7 . The synthetic resin container with a window according to  claim 4 , wherein the base layer is made of an uncolored polyethylene terephthalate resin, and the intermediate layer is made of a colored, opaque polyethylene terephthalate resin. 
     
     
         8 . A method of injection molding the test tube-shaped preform for biaxial stretch blow molding according to  claim 1 , in which an intermediate layer is formed in a base layer in a laminated manner, the method being performed with a use of an injection molding apparatus including a nozzle, the nozzle comprising:
 three cylindrical flow paths for layer formation disposed concentrically about the same axis, the three cylindrical flow paths including an inner flow path and an outer flow path for forming the base layer composed of a major material resin, and a middle flow path for forming the intermediate layer composed of an intermediate layer resin, the middle flow path being disposed between the inner flow path and the outer flow path;   a columnar combined flow path disposed downstream from the three cylindrical flow paths for layer formation, at the columnar combined flow path the three flow paths being combined; and   a shut-off longitudinal rib piece disposed at a downstream end of the middle flow path, the shut-off longitudinal rib piece traversing the middle flow path relative to the circumferential direction and circumferentially interrupting the middle flow path, the method comprising:   supplying the major material resin from the outer flow path and the inner flow path to the combined flow path for a predetermined time period at a predetermined supplying rate;   for a certain period of time within a range of the predetermined time period during which the major material resin is supplied, simultaneously supplying the intermediate layer resin from the middle flow path to the combined flow path at a predetermined supplying rate;   injecting a columnar laminated molten resin 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 and the gate being disposed at a position in the cavity that corresponds to a center of a bottom wall of a bottom of the perform; and   forming a non-laminated section, where the intermediate layer is not formed, that extends in a shape of a longitudinal strip along a central axis direction of the preform on a circumferential wall of the preform, by causing the shut-off longitudinal rib piece to circumferentially interrupt the intermediate layer resin in the middle flow path.   
     
     
         9 . The method of injection molding according to  claim 8 , further comprising:
 configuring the injection molding apparatus to be used such that an opening end of the inner flow path into the combined flow path is shut off or released and further such that an opening degree of the opening end is adjusted, by controlling a position of a tip of a columnar shut-off pin that is slidably inserted into or disposed in a space inward of the inner flow path,   shutting off the opening end, by controlling the position of the tip of the shut-off pin, during the period from when a predetermined time has passed after the supply of the intermediate layer resin is started to at least when the supply of the intermediate layer resin is finished; and   forming the intermediate layer in a laminated manner over an entire area near the bottom of the preform that at least includes the bottom wall.