Injection molding device for preforms

Abstract

The injection molding apparatus of the present invention has a nozzle part (1) for injection-molding a preform for biaxial stretch blow molding in which at least one intermediate layer is laminated on a base layer, and forms an inner flow of the base layer. The channel (15) and the outer flow channel (17), and the middle flow channel (16) forming the middle layer are coaxially arranged, and the middle flow channel (16) is divided into a predetermined number of flow channels by the cut-off longitudinal ribs (20). Of the pair of side walls (20a) located on both sides in the circumferential direction of the longitudinal rib (20), the upstream portion (20b) of each side wall located on the upstream side is an inclined surface whose distance from the downstream side to the upstream side becomes narrower, or The downstream end of the cutoff longitudinal rib (20) enters at least one of the inner flow path (15) and the outer flow path (17).

Description

technical field [0001] The present invention relates to an injection molding apparatus for forming a preform for biaxial stretch blow molding, and more particularly to a preform for forming an intermediate layer made of an intermediate layer resin layered on a matrix layer made of a main material resin The nozzle of the injection molding device for forming parts. Background technique [0002] Biaxially stretched blow molded jars made of ethylene terephthalate (abbreviated as PET hereafter) resin, etc., are used in various fields such as beverages, foods, and cosmetics. In particular, for applications that require gas barrier properties, a base layer made of PET resin as the main material resin is used, and a resin having gas barrier properties such as nylon-based resin and ethylene vinylalcohol copolymer resin is laminated. The altar body of the middle layer. In addition, Patent Document 1 describes a laminated preform as a primary molded product of a laminated jar body by...

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Problems solved by technology

Therefore, there is a possibility that the two layers may be partially peeled off due to the action of shear force due to impact such as dropping.

And, for example, in the application for carbonated beverages, when the interlayer peeling site is partially formed as described above, the carbon dioxide gas permeating the PET resin inner layer breaks into the peeling part, and the peeling becomes difficult due to the pressure of the carbon dioxide gas. Larger, light is scattered or reflected at the peeling interface, peeling can be confirmed from the outside, and the appearance is impaired

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