Method of molding synthetic resin bottle body

Abstract

A technical problem to be solved by this invention is to create a biaxially drawing and blow molding process that can fully make up for a restricted upper limit to the preform body wall thickness. An object of this invention is to provide a biaxially drawn, blow molded bottle which is narrow-mouthed and yet has a substantially expanded body. In principle, the molding process of this invention to solve the technical problems comprises three steps of : (1) injection molding a preform in the shape of a test tube taller than the bottle wherein the preform has a cylindrical mouth opening portion disposed in an upper part of the preform, and wherein the mouth opening portion of the preform serves also as a mouth opening portion of the bottle product; (2) thermally shrinking the preform from an initial height so that portions other than the mouth opening portion of the preform would have a height that is smaller than that of the bottle; and (3) setting this thermally shrunk preform in a blow mold and biaxially drawing and blow molding the preform into the bottle.

Description

technical field [0001] The present invention relates to a bottle made of synthetic resin, and more particularly to a small narrow-mouth bottle formed by biaxial stretch blow molding and a molding method thereof for cosmetic material containers such as mascara and eyeliner. Background technique [0002] Patent Document 1 describes an invention related to a biaxially stretched blow-molded bottle made of polypropylene resin and a molding method thereof. [0003] Patent Document 1: Japanese Patent Application Laid-Open No. 9-52278 [0004] In recent years, biaxially stretched blow-molded bottles have been used in small narrow-mouth bottles used in cosmetic materials such as mascara and eyeliner. The inner diameter of the mouth of this narrow-mouth bottle is about 10mm or less. small diameter. On the other hand, the shape of the preform formed by the injection molding used in the biaxial stretching blow molding is a test tube shape with a mouthpiece part having the same shape a...

AI Technical Summary

Problems solved by technology

[0005] In addition, since cooling water passes through the core mold of the mold for injection molding, there are limitations in reducing the diameter of the core mold, and in terms of reducing the inner diameter of the bottle body portion of the preform and increasing its wall thickness There are also limitations

[0006] As mentioned above, due to the restriction on the shape of the preform, the setting of the wall thickness of the wall of the body part of the preform is limited, especially when the bottle body is over the entire height range of the body part or a part of it is large. In the case of a bulging bottle body, the wall thickness of the bulging part cannot be sufficiently thick, and if the vicinity of the bulging part of the bottle body is pressed with a fingertip, etc., the wall of the bottle body will be easily dented, and not only the contents will appear In case of accidental spraying to the outside, etc., the function of the bottle body will be damaged, and it will also affect the merchandise such as hand feel and sense of quality

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