JPS6073829A - Method of molding biaxially orientated bottle resistant to heat - Google Patents

Abstract

PURPOSE:To extend the part-blow-neck as well as the barrel section thereby orientating the part-below-neck and to improve the heat resistance, by making the war of the barrel section of a preform of a crystalline resin thick such that the inner and outer diameters of the barrel section may be smaller than those of the neck section, and extending the barrel section with the part of the preform above the support ring thereof clamped. CONSTITUTION:Use is made of a neck mold 1, an injection mold 2 and a core mold 3 to injection mold a preform 4 having a neck section 4a, a support ring 4b, and a barrel section 4c. The wall of the barrel section 4c is made thicker than that of the support ring 4b, and the inner and outer diameters of the barrel section 4c are smaller than those of the neck section 4a. After the preform 4 is removed and the core mold 3 is withdrawn, it is clamped by the neck mold 1 and transferred from the temperature regulation position to a blow mold 5. The preform 4 is pushed axially by a rod 7 and when air is blown into the preform, the preform 4 is biaxially orientated except part above the support ring 4b thereby providing a bottle whose part-below-neck is crystallized. Since the barrel section heat resistance, the part-below-neck would not be thermally deformed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for molding a heat-resistant biaxially oriented bottle made of a crystalline resin such as polyethylene terephthalate using stretch blow molding.

Biaxially oriented bottles are formed by elongating an injection or extrusion f IJ foam axially and radially in a mold.

This stretch blow molding produces a 'f + J - y ohm neck.

The body and bottom are biaxially oriented because the retaining ring is held up to the bottom of the neck, but the area directly below is in the same state as when it was injection molded or extruded1, and the pressure resistance of this type of bottle is Improvements in performance such as elasticity, impact resistance, heat resistance, and gas barrier occur in biaxially oriented parts, and since the performance is proportional to the degree of orientation, the area below the neck is closer to the torso than the part near the neck. The parts are better. 1 When such a biaxially oriented bottle is filled with a liquid heated to approximately the same temperature as the molding temperature, the lower neck often deforms. This is because, of the portions subject to biaxial orientation, the lower part of the neck has the lowest degree of orientation, and is still not as thick as the neck.

Therefore, when a biaxially oriented pin is used as a packaging pin for contents that require negative heating light, it is said that the heat resistance of the underside of the neck must be improved by means such as bending. .

This invention was devised to solve the problem of heat resistance in biaxially oriented bottles with the simplest means. The object of the present invention is to provide a new blow molding method that can similarly extend the material to impart a degree of orientation, thereby further improving the heat resistance.

According to the present invention, the body of the preform made of crystalline resin is made thicker, and the inner and outer diameters are smaller than the retaining ring formed in the neck, and the blow cavity is made small. The under-neck molding surface of the preform is provided on the outside along the extension line of the inner diameter of the neck to form an extension space around the under-neck of the preform, and the retaining ring is sandwiched above the retaining ring of the preform. It is characterized by extending the torso from one part to the other.

The present invention will be explained in detail below using illustrated examples.

As shown in FIG. 1, the neck mold 1 is formed into two neck parts 4σ1. by using an injection mold 2 and a core mold 3. A preform 4 having a retaining ring 4b, a body portion 4C, etc. on its body is injection molded.

In this case, the retaining ring 4b is molded on the bartending line so that the neck portion 4α of the preform 4 can be held between the neck die 1 and the retaining ring 4b.

Further, the body portion 4C is formed to have a thick wall starting from the retaining ring 4b, and its inner and outer diameters are each smaller than the inner and outer diameters of the neck portion 4a. In the illustrated example, both the inner and outer surfaces from the retaining ring 4b are curved inward and formed to have the same thickness up to the body 4C, but the cross-sectional shape of that part varies depending on the product shape. After releasing the preform 4 from the injection mold 2 and pulling out the core mold 3, the upper part of the retaining ring 4b is held between the neck mold 1 and transferred to the temperature control position, and then transferred to the blow mold 5.
Transfer to.

Under-neck molding surface 6α of the cavity 6 that the blow mold 5 has
The extension line A of the inner diameter of the neck is also provided on the outside in advance, and the mold is closed with the preform 4 sandwiched between them, and when the preform 4 is positioned in the center of the cavity, the lower neck extends around the lower neck. This will create a space for you to do so.

Then, when the preform 4 is pressed in the axial direction by the rod 7 into which the preform 4 is inserted, the body 4C is extended from the base 4d of the retaining ring 4b. When it is clamped to below the neck as in the conventional method, the stretching occurs from the bottom of the clamped part, and the part below the neck is not stretched and injection molded! It is in a state of being.

Furthermore, air is blown into the preform 4.

Since there is a space between the under-neck molding surface 6a and the extended under-neck, the extension in the radial direction occurs from the retaining ring 4b, and the under-neck also extends to the mold surface.

As a result, the preform 4 is biaxially oriented from the retaining ring 4b, resulting in a bottle that is crystallized even below the neck1. The diameter of the preform is reduced from the bottom, and the under-neck molding surface of the blow mold cavity is also provided on the outside along the extension line of the inner diameter of the neck, so that the under-neck of the preform can be expanded in both vertical and horizontal directions. The body is biaxially oriented from the retaining ring part, making the bottom of the bottle heat resistant as well, so even if the contents are heated and filled, the bottom of the neck will not be thermally deformed like in the past. No 3. Further, it has the advantage that it can be molded in the same manner as conventional methods, and does not require heat treatment, so that it does not increase costs.

[Brief explanation of drawings]

The drawings illustrate the method of molding a plane-1 thermally biaxially oriented mold according to the present invention, and FIG. 1 is a vertical cross-sectional view of the mold during preform molding, and FIG. 2 is a vertical cross-sectional view of the blow mold when the mold is closed. Figure, 3rd
The figure is a longitudinal cross-sectional view showing the relationship between the under-neck of the preform and the under-neck molding surface of the blow cavity, and FIG. 4 is a vertical cross-sectional view of the same during stretch blow layering. j ・・・・・・・・・Injection mold 2 ・Four-phase neck type 3 ・・・・・・・Core type 4 ・Long/Mountain free form 4α・・・・・・・・・Neck part 4b・・・・・・・
...Retaining ring 4c ...Body part 4d
・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・Blow mold 6 ・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・Blow mold 6

Claims (1)

[Claims] When forming a biaxially oriented bottle by stretch blowing a preform made of crystalline resin such as polyethylene terephthalate, the body of the preform is made thicker, and the retaining ring formed at the neck has a blind area on both the inner and outer diameters. is formed to have a diameter smaller than the inner and outer diameters of the blow cavity, and the molded surface under the blow cavity is provided outside the extension line of the inner diameter of the neck part,
A method for molding a heat-resistant biaxially oriented bottle, comprising forming an extension space around the lower neck of the preform, clamping the preform above the retaining ring, and extending the body from the retaining ring.