JPH0857942A - Heat resistance and pressure resistance self-standing vessel - Google Patents

Abstract

PURPOSE: To improve a drop-impact proofing property and moldability without causing a creep deformation of the bottom during heat disinfection by radially enlarging legs, and allowing the shorter legs to be a specific dimensional rate either in the distance from a leg ground contact plane to the lower surface of the bottom central part, or in the distance from the leg ground contact plane to the lower surface of a periphery of the bottom central part. CONSTITUTION: The bottom 5 has a self-standing structure where a plurality of legs 6 are radially enlarged around the periphery 8 of a bottom central part, and trough lines 9 are made among these legs 6. Crystallization is done over each part 10 near at least time bottom central part 7, the periphery 8 of the bottom central part and the central parts of the trough lines, and after filling a content therein, a disinfection treatment is performed. The shorter distance either in the distance 14 from the leg ground contact plane of the vessel to the lower surface of the bottom central part, or in the distance 15 from the leg ground contact plane to the lower surface of the periphery of the bottom central part is made 1.5-9.0% relative to the bottom diameter 16 of the vessel.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a self-standing container made of a biaxially stretched blow-molded saturated polyester resin, which is suitable for filling carbonated drinks, soft drinks and the like. The present invention relates to a heat-resistant and pressure-resistant self-supporting container having improved heat resistance and pressure resistance during heat sterilization and having excellent impact resistance and shapeability.

[0002]

2. Description of the Related Art Conventionally, as a heat-resistant and pressure-resistant container, the bottom portion is bulged to form a hemispherical shell shape in order to enhance the internal pressure resistance of the container body, and a base cup molded in a bottomed cylindrical shape is attached to this Then, the mainstream is a container with a self-supporting function.
However, the use of the base cup requires that the base cup be separately molded and mounted and fixed, the weight of the container becomes large and the shape also becomes large, and hot water is sufficiently supplied to the bottom of the container during the heat sterilization process. There were various problems such that the heat sterilization of the contents could not be smoothly carried out because it did not reach, and that at this time, water was accumulated in the base cup and it was difficult to drain it quickly.

Further, it is desired to effectively reuse a used empty container from the viewpoint of resource saving and environmental problems.
In a container equipped with a base cup, the container body and base are usually used.
Since the materials of the scup and the adhesive are different, they must be separated when they are reused, and there is a problem that the process cost becomes high.

Due to these problems, a heat-resistant and pressure-resistant container which does not require a base cup has been desired. Several proposals have been made for pressure-resistant containers that do not require a base cup, and generally, a plurality of legs are radially bulged around the center of the bottom, and valleys are formed between these legs. It has either a structure in which a line portion is formed or a champagne type structure. For example, Japanese Patent Publication Nos. 48-5708, 59-40693, 61-9170, and 63-202424. And Japanese Patent Laid-Open No. 3-4
3342 publication.

However, although the container described in each of these publications can obtain satisfactory performance as a pressure resistant container, it has sufficient performance when used as a heat resistant and pressure resistant container for performing a heat sterilization process. Can't get That is, in the containers described in the above-mentioned publications, since the unstretched region or the low stretched region exists in the center of the bottom and the periphery of the center, the temperature of the contents is 5 at the time of heat sterilization.
When the temperature rises from 0 ° C. to about 70 ° C., the internal pressure increases, and the container material itself easily undergoes creep deformation, so that the bottom center portion and the low-stretching region around the center portion undergo creep deformation. Raising and protruding, the container loses its self-sustaining stability.

Therefore, for example, Japanese Patent Laid-Open No. 4-154535.
It is conceivable to use the container described in JP-A-5-85535. Since this container is a container in which the center part of the bottom is crystallized and the periphery of the center is sufficiently stretched,
It is considered that creep deformation of the bottom part can be suppressed to some extent when the internal pressure increases during heat sterilization. However, even in the case of this container, it is difficult to sufficiently stretch the valley line portion formed between the leg portions, and a low stretched region remains in this portion, so that the portion is cleared during heat sterilization. -Because of the deformation of the bottom, the bottom part protrudes and loses self-supporting stability, or even if the self-supporting stability is maintained, the penetration line drops significantly and the projection of the bottom center part due to creep causes a drop impact. There is a problem of loss of practicality such as loss of sex.

[0007]

Therefore, in order to solve this problem, a specific portion of the bottom portion that undergoes creep deformation during heat sterilization is thermally crystallized so that the portion undergoes creep deformation during heat sterilization. A method of suppressing is considered. However, when the specific portion of the bottom portion is thermally crystallized in this way, there is a phenomenon in which the material becomes brittle due to crystallization and is easily broken when a drop impact is applied to the container. As a result of pursuing this cause, in order to prevent the bottom of the container from being destroyed, in order to prevent the container from undergoing a heat sterilization process after filling the contents, (a) the distance from the leg ground contact surface to the bottom central bottom surface, or (B) The present invention has been achieved by finding that the shorter distance of the distance from the ground contact surface of the leg portion to the lower surface of the peripheral portion of the bottom center portion is set to a specific ratio with respect to the bottom diameter of the container.

That is, according to the present invention, (a) the distance from the ground contact surface of the leg portion to the lower surface of the center of the bottom portion, or (b) the ground surface of the leg portion to the bottom portion of the container that has been subjected to a heat sterilization treatment step after filling the contents. By setting the shorter distance from the bottom surface of the peripheral part of the central part to 1.5 to 9.0% of the bottom diameter of the container, the bottom part creeps and deforms during heat sterilization, and self-sustaining stability is not lost. The present invention also provides a heat resistant and pressure resistant self-supporting container having excellent drop impact resistance and shapeability.

[0009]

That is, the invention of the present invention is a biaxially stretched blow molded saturated polyester resin container comprising a mouth, a neck, a neck, a body and a bottom, wherein the bottom is the center of the bottom. Radially swelling a plurality of legs around the periphery of, has a self-supporting structure in which a valley line portion is formed between these legs, at least the center of the bottom,
The peripheral part of the center of the bottom part and the part near the center part of the bottom of the valley line part are crystallized, and (a) from the ground contact surface of the leg to the bottom surface of the bottom part of the container that has undergone the heat sterilization treatment step after filling the contents. Of the distance h1 or (b) the distance h2 from the leg ground contact surface to the lower surface of the peripheral part at the center of the bottom, whichever is shorter, is 1.5 to 9.0% of the bottom diameter of the container. A heat-resistant and pressure-resistant self-supporting container.

The resin used in the present invention is preferably a thermoplastic polyester resin whose main repeating unit is ethylene terephthalate. As the thermoplastic polyester resin, a resin containing a homopolymer of polyethylene terephthalate as a main component is used. Further, as the resin used in the present invention, a polypropylene resin, which is a synthetic resin having mechanical properties improved by biaxial stretching and having crystallinity, can be mentioned.

As the thermoplastic polyester resin, an aromatic dicarboxylic acid such as isophthalic acid, naphthalene dicarboxylic acid, diphenyl dicarboxylic acid, diphenoxyethane dicarboxylic acid, diphenyl ether dicarboxylic acid or diphenyl sulfone dicarboxylic acid is used as a part of the terephthalic acid component. Alicyclic dicarboxylic acids such as hexahydroterephthalic acid and hexahydroisophthalic acid; aliphatic dicarboxylic acids such as adipic acid, sebacic acid and azelaic acid; P-β-
A copolymer obtained by substituting one or more other difunctional carboxylic acids such as hydroxyethoxybenzoic acid and oxyacids such as ε-oxycaproic acid can be used.

In the thermoplastic polyester resin, a part of the ethylene glycol component is, for example, trimethylene glycol, tetramethylene glycol, hexamethylene glycol, decamethylene glycol, neopentylene glycol, diethylene glycol, 1,1-cyclohexanedimethylol. , 1,4-cyclohexanedimethylol, 2,2 (4'-β-hydroxyethoxyphenyl)
It may be a copolymer obtained by substituting one or more polyfunctional compounds of other glycols such as sulfonic acid and functional derivatives thereof for copolymerization.

The thermoplastic polyester resin used in the container of the present invention has an intrinsic viscosity (abbreviated as IV) of 0.
It is 7 to 0.9, preferably 0.75 to 0.85.

Further, the thermoplastic polyester resin used in the present invention may appropriately contain additives such as colorants, heat deterioration inhibitors, antioxidants, ultraviolet absorbers, antistatic agents, antibacterial agents and lubricants. it can.

In the present invention, (A) the central part of the bottom, (B) the peripheral part of the central part of the bottom,
(C) In addition to the portion near the center of the bottom of the valley portion, part or all of the portion from the peripheral edge of the leg to the ground contact portion, the portion near the center of the bottom of the valley portion and the leg A part or all of the portion between the edge of the peripheral portion and the ground portion may be added. Further, in the present invention, the distance h1 from the ground contact surface of the leg portion to the lower surface of the center portion of the bottom is 14 in FIG.
The distance h2 from the ground contact surface of the leg to the lower surface of the peripheral part of the center of the bottom is the distance indicated by 15 in FIG.

In the container of the present invention, among these, at least (A) the central portion of the bottom, (B) the peripheral portion thereof, and (C).
A portion of the valley line portion near the center of the bottom is crystallized, and after filling the contents, the container is subjected to a heat sterilization process. ) Of the distance h2 from the leg ground contact surface to the lower surface of the peripheral part of the center of the bottom, the shorter one is 1.5 to 9.0% of the bottom diameter of the container.
By having a shape that is, the shapeability of the container is improved, and the creep deformation of the container that occurs in the heat sterilization process of the contents (conditions described in the manufacturing standard for soft drinks) is suppressed,
Further, it is possible to maintain the self-sustaining stability of the container, and it is possible to prevent the bottom portion from being damaged when the container is dropped.
If it is less than 1.5%, the bottom of the container will be destroyed, resulting in 9.0%.
If it exceeds, the shapeability of the legs of the container deteriorates. Furthermore, the partially crystallized part at the bottom is whitened in a star shape, which is excellent in container design. The bottom diameter of the container means a cylindrical portion having the maximum diameter in the vicinity of the connection between the bottom of the container and the body, for example, a portion indicated by 16 in FIG.

Next, each part of the bottom of the self-supporting container will be described. The (A) bottom center means, for example, the lattice-shaped portion 7 in FIG. (B) The peripheral portion of the central portion of the bottom portion means, for example, the shaded portion 8 in FIG. (C) The portion near the center of the bottom of the valley line is the portion near the center of the inside of the valley,
5 to 65% of the entire valley line portion, for example, a portion indicated by 10 in FIG. (D) The part that extends from the peripheral edge of the center of the bottom of the leg to the ground contact part refers to the part of the leg that extends from the peripheral edge of the center of the bottom of the leg to the ground contact part. This is a portion indicated by 11 in FIG. (E) The portion near the center of the bottom of the valley line portion and the portion between the edge of the peripheral portion of the leg portion and the ground contact portion are, for example, portions indicated by 12 in FIG.

In the present invention, the heat sterilization step is defined by the manufacturing standard of soft drinks defined in the standard (extract) of foods, additives, etc. of Ministry of Health and Welfare Notification 370 (revised in 1984).
In the case of H4.0 or less, the temperature of the central part is 6
It refers to a method according to the method of heating at 5 ° C. for 10 minutes or the method of sterilizing by a method having the same or higher efficacy. In the present invention, the content to be filled in the container is not particularly limited, drinking water for heat and pressure, carbonated beverages that must be heat sterilized, that is, carbonated juice with fruit juice,
Carbonated beverages containing lactic acid bacteria and ordinary carbonated beverages.

[0019]

EXAMPLES The present invention will be described in detail below with reference to examples.

Example 1 A preform obtained by injection-molding polyethylene terephthalate (IV = 0.85) was locally heated at the mouth and neck and the upper part of the neck with an infrared heater to cause whitening and crystallization. did. Next, the preform body was heated to a temperature suitable for stretching, placed in a blow mold, and subjected to biaxial stretch blow molding. At this time, keep the body of the blow mold at 70-80 ° C,
Heat set for 2 seconds. After heat setting, the container was taken out from the mold.

Next, the bottom of the container was heated using an infrared heater. At this time, a shielding plate having a structure in which only a specific part passes is used to obtain a container in which the bottom center part of the bottom part of the container, the peripheral part of the bottom center part, and the part near the bottom center part of the valley line part are crystallized. It was (FIGS. 1 and 2) Further, as a result of the evaluation, the shapeability of the legs was good.

Twelve of these containers were prepared, and at 5 ° C., 2.5 gas volume of carbonated water was filled up to the permeation line of 43 mm, and after capping, a heat sterilization process of applying a hot water shower at 70 ° C. for 30 minutes was performed. went. After that, 20 ℃
And water for about 10 minutes to cool. (FIG. 3) (a) The distance h1 from the leg ground contact surface to the bottom center bottom surface of the container that has undergone the heat sterilization process after filling the contents, or (b) the leg ground contact surface to the bottom center peripheral area. Of the distance h2 to the lower surface, the shorter distance was 1.6% of the bottom diameter of the container. Next, as a drop test, 12 containers were dropped on the concrete from a height of 2.0 m in an upright state, and the presence or absence of breakage at the bottom of the container was examined. As a result, there was no breakage at the bottom of the container. . Table 1 shows the evaluation results.

Example 2 In Example 1, (a) the distance h from the ground contact surface of the leg portion to the lower surface of the bottom center portion of the container which has undergone the heat sterilization process after filling the contents.
1 or (b) A container having a shorter distance of 5.3% of the bottom diameter of the container out of the distance h2 from the ground contact surface of the leg portion to the lower surface of the peripheral portion at the center of the bottom portion was obtained. Table 1 shows the evaluation results. Example 3 In Example 1, the distance h from the (a) leg ground contact surface of the container that has undergone the heat sterilization process after filling the contents to the lower surface of the bottom center part
1 or (b) A container having a shorter distance of 9.0% of the bottom diameter of the container from the distance h2 from the ground contact surface of the leg portion to the lower surface of the peripheral portion at the center of the bottom portion was obtained. Table 1 shows the evaluation results.

Comparative Example 1 In Example 1, the distance h from (a) the leg ground contact surface to the bottom central bottom surface of the container which has undergone the heat sterilization process after filling the contents.
1 or (b) A container having a shorter distance of 1.0% of the bottom diameter of the container from the distance h2 from the ground contact surface of the leg portion to the lower surface of the peripheral portion at the center of the bottom portion was obtained. Table 1 shows the evaluation results. Comparative Example 2 In Example 1, the distance h between the (a) leg ground contact surface and the bottom central bottom surface of the container that has undergone the heat sterilization process after filling the contents.
1 or (b) A container having a shorter distance of 12.0% of the bottom diameter of the container out of the distance h2 from the ground contact surface of the leg portion to the lower surface of the peripheral portion at the center of the bottom portion was obtained. Table 1 shows the evaluation results.

[0025]

[Table 1] (Note 1) Display of evaluation result of leg shapeability ○: Good shapeability, ×: Poor shapeability

[0026]

As described above, according to the present invention, a heat-resistant and pressure-resistant self-supporting container that suppresses the bottom projection during heat sterilization of the container contents to maintain self-sustaining stability and is also excellent in drop impact resistance. Can be provided. Further, since the container according to the present invention does not require a base cup, hot water at the time of heat sterilization reaches the bottom of the container sufficiently, and heat sterilization of the contents can be smoothly performed. Reuse becomes easy.

[Brief description of drawings]

FIG. 1 is a front view of a self-supporting container of the present invention.

FIG. 2 is a bottom view of the self-supporting container of the present invention.

FIG. 3 is a partial view of the bottom of the contents filling container of the present invention.

FIG. 4 is a view showing each part of the bottom portion of the container of the present invention.

[Explanation of symbols]

1 Self-supporting container 2 Mouth neck part 3 Neck upper part 4 Body part 5 Bottom part 6 Leg part 7 Bottom part central part 8 Bottom part peripheral part of the center part 9 Valley line part 10 Bottom part of the valley line part 11 Bottom part of the leg part The part from the peripheral edge of the central part to the grounding part 12 The part between the bottom part of the valley line part close to the center and the part from the peripheral edge of the leg to the grounding part 13 Grounding part 14 Leg contact Distance from the ground to the lower surface of the center of the bottom h1 15 Distance from the ground contact surface of the leg to the lower surface of the peripheral part of the center of the bottom h2 16 Diameter of the bottom of the container

Claims (1)

[Claims] 1. A biaxially stretched blow molded saturated polyester resin container comprising a mouth and neck, a neck, a body and a bottom, wherein the bottom has a plurality of legs around the periphery of the center of the bottom. It has a structure that can swell radially and form a valley line between these legs and at least in the center of the bottom, the periphery of the center of the bottom and the center of the bottom of the valley. (A) Distance h1 from the ground contact surface of the leg to the lower surface of the center of the bottom, or (b) from the ground contact surface of the leg to the bottom of the container that has undergone a heat sterilization process after the close portion is crystallized and the contents have been filled. A heat-resistant and pressure-resistant self-supporting container, characterized in that, of the distance h2 from the lower surface of the peripheral portion of the central portion, the shorter distance is 1.5 to 9.0% of the bottom diameter of the container.