JPH0641298B2 - Polyester resin container - Google Patents

Description

The present invention relates to a polyester resin container, and more particularly to a container for carbonated beverages containing fruit juice. It is intended to obtain a container having a stable bottom shape by improving the pressure resistance and heat resistance of the bottom of the container. It is intended.

Since a container for carbonated beverages containing fruit juice is heat-sterilized under a carbon dioxide pressure, it is necessary to increase the pressure resistance and heat resistance of the bottom of the container where stretching is not sufficient.

In order to increase the pressure resistance of the bottom, it is effective to crystallize the bottom, but in this case, if the bottom of an ordinary container is heated for a certain period of time or more, the crystallization part deforms and stabilizes. In some cases, a hemispherical bottom shape cannot be obtained.

The present invention, as described in the claims, the bottom of the polyester ester resin container, a plurality of thick ribs are formed radially from the center, the bottom is crystallized in the rib and the peripheral portion of the rib, By forming a star-shaped crystallization part having the outer end of the thick rib as a pointed portion at the bottom, the pressure resistance and heat resistance of the bottom of the container are improved, The effect that the bottom has a stable shape is achieved.

The configuration of the present invention will be described based on the embodiments shown in the drawings.

1 and 2 are a plan view and a vertical cross-sectional view of a bottom portion of a polyester resin container according to the present invention.
A plurality of thick ribs 3 that bulge from the center are formed on the inner surface of the bottom portion 2 of the rib 2.
Thus, the rib portion is made thicker than the other portions of the bottom portion 2. It is desirable to form at least four ribs 3 in consideration of pressure resistance against heat sterilization and heat resistance of the bottom portion 2.

The bottom portion 2 is crystallized over the ribs 3 and the peripheral portion of the ribs 3, and the shape of the crystallization portion 4 is such that the outer end of the thick rib 3 is sharpened as shown in FIG. It has a star shape with a head. That is, by providing the thick ribs 3 radially on the bottom portion 2, the effect of crystallization is improved, and the crystallization portion 4 becomes a star shape with the outer ends of the thick ribs 3 as the cusps. It is possible to improve the pressure resistance and heat resistance strength of the bottom portion 2.

In the method of molding the polyester resin container described above, a plurality of thick ribs bulging from the center are formed in advance on the inner surface of the bottom of the preform, and the preform is molded into a container by biaxial stretch blow molding. Thereafter, the bottom of the container is heated at a crystallization temperature of at least 70 ° C. or higher to crystallize the rib and the peripheral portion of the rib.

Next, regarding the elongation (deformation) of the bottom of the container due to heating, the following table shows the experimental results of crystallization with ribs at the bottom of the container, crystallization without ribs, and crystallization with ribs.

From the above results, it is clear that the rate of elongation (change) at the bottom of the container due to heating is far less than that of crystallization with ribs at the bottom, and this experiment also shows that the bottom of the container has a radial thickness. The container bottom formed by forming ribs and crystallizing the ribs and the peripheral portion of the ribs has excellent pressure resistance and heat resistance strength. Although in the above-mentioned embodiment, the ribs are formed on the inner surface of the bottom, the same effect can be obtained by the ribs even if they are formed on the outer surface of the bottom.

As described above, the present invention forms a plurality of thick ribs radially running from the center of the bottom of the container on the bottom of the container, crystallizes the bottom at the rib and the peripheral portion of the rib, and the outer end of the thick rib is formed. By forming a star-shaped crystallization part having a pointed portion on the container bottom, the pressure resistance against heat at the container bottom and heat resistance strength are improved, and the container bottom is prevented from changing due to heating, It is possible to obtain a stable bottom shape.

[Brief description of drawings]

FIG. 1 is a plan view of a container bottom portion according to the present invention, and FIG. 2 is a vertical sectional view of the same. 1: Container, 2: Bottom part, 3: Rib, 4: Crystallization part.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yukio Koshitaka 310 Minoritadai, Matsudo City, Chiba Prefecture Yoshino Industry Co., Ltd. Chiba Plant (72) Inventor Takao Iizuka 310 Minoritadai, Matsudo City, Chiba Prefecture Chiba Plant, Yoshino Industry Co., Ltd. ( 72) Inventor Yoshimi Shimoyama 310 Chiba Plant, Matsudo City, Chiba Prefecture Yoshino Industry Co., Ltd. Chiba Factory (56) References JP-A-54-16283 (JP, A) JP-A-55-64039 (JP, A) 58-121809 (JP, U) Actually developed 54-98459 (JP, U) JP-A-55-71243 (JP, A) JP-A-56-75834 (JP, A)

Claims (1)

[Claims] 1. A polyester resin container formed by biaxially stretch blow molding a preform, wherein a plurality of thick ribs are radially formed from the center of the bottom portion, and the bottom portion surrounds the ribs and the ribs. A polyester resin container characterized in that a star-shaped crystallized portion, which is crystallized in a portion and has an outer end of the thick rib as a pointed portion, is formed in the bottom portion.