| 摘要 |
A technical problem of this invention is to minimize fluctuations in the height position of a leading edge of an intermediate layer of a preform in a circumferential direction when an injection molding device is used to mold the preform in a test tube by laminating substrate layers of a main resin with an intermediate layer, while segmenting the intermediate-layer resin in the circumferential direction into small streams A principal means of solving the above-described technical problem is a preform-molding device having a nozzle section comprising 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 comprising 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. |
