Preform and bottle

Abstract

For a preform, on an outer circumferential side of a base material layer, which is made of a first colored resin, a colored layer, which is made of a second colored resin having a color different from that of the first colored resin and which forms a gradation region in which the layer thickness gradually decreases upward, is formed. Furthermore, on the outer circumferential side of the colored layer, a coating layer, which is made of the first colored resin, is formed.

1 . A synthetic resin preform comprising a colored layer forming a gradation region in which a layer thickness gradually decreases, wherein,
 on an outer circumferential side of a base material layer made of a first colored resin, the colored layer, which is made of a second colored resin having a color different from that of the first colored resin and which forms the gradation region in which the layer thickness gradually decreases upward, is formed, and, on the outer circumferential side of the colored layer, a coating layer made of the first colored resin is formed.   
     
     
         2 . The preform according to  claim 1 , wherein
 the preform is molded, from a state where the first colored resin is filled in a gate disposed in correspondence with a middle of a bottom of the preform, by injecting the first colored resin into a cavity of a mold through the gate for a first predetermined time period and by injecting the second colored resin material for a second predetermined time period, and   by setting a starting time point of the first predetermined time period to be behind a starting time point of the second predetermined time period, setting a finishing time point of the first predetermined time period to be behind a finishing time period of the second predetermined time period, and setting an injection rate of the second colored resin to be faster than an injection rate of the first colored resin, the first colored resin is caused to flow while stretching the second color resin after penetrating a center portion of the second colored resin located inside the cavity of the mold, and   the colored layer is formed on the outer circumferential side of the base material layer, and the coating layer is formed on the outer circumferential side of the colored layer.   
     
     
         3 . The preform according to  claim 1 , wherein the first colored resin has an IV in the range from 0.5 to 0.63. 
     
     
         4 . A bottle obtained by biaxially stretch blow molding the preform according to  claim 1  and decorated with gradations associated with color density that are caused to appear by the colored layer. 
     
     
         5 . The preform according to  claim 2 , wherein the first colored resin has an IV in the range from 0.5 to 0.63. 
     
     
         6 . A bottle obtained by biaxially stretch blow molding the preform according to  claim 2  and decorated with gradations associated with color density that are caused to appear by the colored layer. 
     
     
         7 . A bottle obtained by biaxially stretch blow molding the preform according to  claim 3  and decorated with gradations associated with color density that are caused to appear by the colored layer. 
     
     
         8 . A bottle obtained by biaxially stretch blow molding the preform according to  claim 5  and decorated with gradations associated with color density that are caused to appear by the colored layer.