PREFORM EXTRUSION MOLDING APPARATUS, METHOD FOR EXTRUSION MOLDING, AND PREFORM

摘要

A process includes: supplying a main resin from outer and inner flow channel, to a joined flow channel at a predetermined supply velocity for a predetermined time; supplying a second resin from a middle flow channel to the joined flow channel simultaneously with the main resin at a predetermined supply velocity for a certain time within the predetermined time; and sliding a shut-off pin to bring the pin forefront to a predetermined position near an outlet of the inner flow channel, open to the joined flow channel, before the second resin is supplied, or during a time starting after a time from the start of the second resin supply and ending with the termination of the supply, so that the velocity of main resin supply from the inner flow channel to the joined flow channel is reduced to a predetermined level by adjusting the degree of aperture for the outlet.

主权项

1. A device for injection molding a preform in a test tube shape for biaxial stretching and blow molding use, in which preform a second-resin layer serving as an intermediate layer is laminated with main-resin layers that make up a shape of the preform, the device having a nozzle section for forming a joined resin fluid by allowing a second resin for forming the second-resin layer to join a main resin for forming the main-resin layers, and having a mold disposed ahead of the nozzle section, said nozzle section comprising:
three cylindrical layer-forming flow channels including an outer flow channel, a middle flow channel, and an inner flow channel in an outside-to-inside order, a joined flow channel connected to these three flow channels and extended to the head of the nozzle section, wherein the main resin is passed through the outer flow channel and inner flow channel, and the second resin is passed through the middle flow channel, and a rod-like shut-off pin disposed on an inner side of the inner flow channel and slidably inserted therein, wherein an outlet of the inner flow channel which is open to the joined flow channel is shut off or opened, and a degree of aperture can be adjusted, by controlling the position of a forefront of the shut-off pin.