JP7552056B2 - Plastic containers - Google Patents

Description

The present invention relates to a synthetic resin container that can be used for applications such as carbonated beverages, where the inside of the container is under positive pressure after the contents are filled and sealed.

Conventionally, synthetic resin containers are made by forming a bottomed cylindrical preform using a thermoplastic resin such as polyethylene terephthalate, and then molding this preform into a bottle shape by biaxial stretch blow molding or the like. These containers are commonly used in a wide range of fields as containers for various beverages, seasonings, etc.

This type of synthetic resin container can be broadly divided into rectangular bottles, which have a rectangular tubular shape, and round bottles, which have a cylindrical shape, but the applicable container shapes are limited depending on the application. For example, in containers used for carbonated beverages, the carbon dioxide gas creates positive pressure inside the container after it is filled and sealed, so the container is usually cylindrical in shape to distribute the pressure evenly and prevent the shape from deforming significantly and unevenly (see, for example, Patent Document 1).

On the other hand, rectangular bottles, which have a rectangular cylindrical container shape, have the advantage of being more efficient to store when packed for transportation, and also being more space-efficient when displayed in stores. For this reason, in order to use rectangular bottles for carbonated beverages, for example, Patent Document 2 attempts to suppress the bulging of the container body due to internal pressure by forming annular reinforcing ribs on the container body, which is formed into a rectangular cylindrical shape.

However, merely forming a circular reinforcing rib as in Patent Document 2 was not sufficient to sufficiently suppress the expansion of the container body due to internal pressure.
In general, after the contents are filled and sealed around the body of a container, a label indicating the contents is wrapped around it before the container is put on the market. Therefore, if the expansion of the body of the container due to internal pressure cannot be sufficiently suppressed, not only will it be difficult to pack the container into a carton, but there will also be problems such as the label rubbing against each other and being damaged by vibrations during transportation.

In addition, in recent years, as the use of this type of synthetic resin container has become more common in a wide range of fields, there is a demand for differentiation from other products and increasing the product's appeal. Conventionally, the applicable container shapes were limited to containers for carbonated beverages and other contents, but if a rectangular cylindrical container shape could be applied to these containers, it would be possible to diversify the design and increase the product's appeal.

Therefore, in Patent Document 3, the inventors proposed a synthetic resin container that has a rectangular cylindrical shape but can sufficiently suppress the expansion of the container body due to internal pressure.

Japanese Patent Application Publication No. 10-264917 JP 2008-7147 A JP 2018-2293 A

The inventors conducted extensive research to further improve pressure resistance and to more effectively suppress the expansion of the container body due to internal pressure, which resulted in the completion of the present invention.

The synthetic resin container of the present invention has a mouth, a shoulder, a body, and a bottom, and can be used in applications where the inside of the container is at positive pressure after filling and sealing the contents, wherein the body is formed in a basic rectangular cylindrical shape and has a recess that recesses into the container along the circumferential direction so that each corner of the body is formed with a bottom surface that bridges between the widthwise center of one body side surface and the widthwise center of the other body side surface adjacent to each other via the corner portion, and a truncated pyramidal portion having a circumferential surface that is inclined along the height direction and in which the corner portion protrudes outward from the container relatively to the recess, the truncated pyramidal portion being arranged alternately along the height direction, and at least at the widthwise center of the body side surface, the bottom surface of the recess is inclined along the height direction in a direction opposite to the circumferential surface of the truncated pyramidal portion.

According to the present invention, a synthetic resin container is provided which can be used in applications where the inside of the container is under positive pressure after the contents are filled and sealed, and which has a body formed in a basic rectangular cylindrical shape, while effectively suppressing deformation due to expansion of the body caused by internal pressure.

1 is a perspective view showing an outline of a synthetic resin container according to an embodiment of the present invention. 1 is a plan view showing an outline of a synthetic resin container according to an embodiment of the present invention. 1 is a front view showing an outline of a synthetic resin container according to an embodiment of the present invention. 1 is an oblique side view showing an outline of a synthetic resin container according to an embodiment of the present invention, viewed from a direction at an angle of 45° with respect to the front. FIG. 4 is an end view taken along line AA of FIG. FIG. 4 is a BB end view of FIG. 3. 4 is an explanatory diagram showing an end view taken along line AA in FIG. 3 and an end view taken along line BB in FIG. FIG. 4 is a CC end view of FIG. 3. FIG. 2 is an explanatory diagram showing the state in which carbonated water is filled and sealed in the embodiment. FIG. 13 is an explanatory diagram showing a cross-sectional shape of a container body in a conventional example. FIG. 8 is an explanatory diagram showing a cross-sectional shape of a container body part of another conventional example, corresponding to FIG. 7 .

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a perspective view of a synthetic resin container according to this embodiment, seen from diagonally above, FIG. 2 is a plan view, FIG. 3 is a front view, and FIG. 4 is an oblique side view seen from a direction diagonally 45° from the front.
5 is an end view taken along line A-A in FIG. 3, FIG. 6 is an end view taken along line B-B in FIG. 3, FIG. 7 is an explanatory diagram showing the end view taken along line A-A in FIG. 3 and the end view taken along line B-B in FIG. 3 superimposed thereon, and FIG. 8 is an end view taken along line C-C in FIG. 3, and in these end views, the thicknesses appearing at the end faces are omitted.

The container 1 shown in these figures has a mouth 2, a shoulder 3, a body 4, and a bottom 5, and the body 4 is formed in a basic rectangular cylindrical shape, giving it a container shape generally known as a rectangular bottle.

Such a container 1 can be manufactured by creating a bottomed cylindrical preform using a thermoplastic resin by injection molding, compression molding, or the like, and then molding this preform into the desired container shape by biaxial stretch blow molding, or the like.

The thermoplastic resin used may be any resin that can be blow molded. Specifically, thermoplastic polyesters such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, amorphous polyarylate, polylactic acid, polyethylene furanoate, or copolymers thereof may be used, and in particular, ethylene terephthalate-based thermoplastic polyesters such as polyethylene terephthalate may be preferably used. Two or more of these resins may be mixed, or other resins may be blended. Polycarbonate, acrylonitrile resin, polypropylene, propylene-ethylene copolymer, polyethylene, etc. may also be used.
Furthermore, the preform is not limited to being molded into a single layer, but can also be molded into multiple layers including a gas barrier layer, etc., depending on the properties required for the container 1.

The mouth 2 is a cylindrical portion through which the contents are taken out, and a lid (not shown) that seals the inside of the container is attached to the mouth 2 .
The lower end of the mouth 2 is connected to a shoulder 3 that expands in diameter toward the body 4 and connects the mouth 2 and the body 4. In the illustrated example, the shoulder 3 is formed in a generally truncated cone shape, but the shape of the shoulder 3 is not limited thereto.

The body 4 occupies most of the height of the container 1, with its upper end connected to the shoulder 3 and its lower end connected to the bottom 5. In the example shown, the bottom 5 has multiple legs 50 arranged radially and rotationally symmetrically around the central axis at equal intervals so that the container 1 is stable and self-supporting even when the container is under positive pressure. However, the shape of the bottom 5 is not particularly limited as long as the container 1 can stand on its own even after it is filled with the contents and sealed.

Here, the height direction refers to the direction perpendicular to the horizontal plane when the container 1 is stood upright on the horizontal plane with the mouth 2 facing up, and defines the up-down, left-right and length-width directions of the container 1 in this state (the state shown in Figure 3 or Figure 4).
In addition, in Figs. 3 and 4, the central axis C is indicated by a dashed line, but unless otherwise specified, a cross section cut along a plane perpendicular to the central axis C will be referred to as a transverse cross section.

In this embodiment, the body 4 is preferably formed in a basic shape of a square tube in plan view with rounded corners as shown in FIG. 2, but is not limited to this.

The body 4 also has recesses 41 and truncated pyramid-shaped portions 40 arranged alternately along the height direction. In the illustrated example, five recesses 41 and four truncated pyramid-shaped portions 40 are arranged alternately along the height direction, but the number of recesses 41 and the number of truncated pyramid-shaped portions 40 can be changed as appropriate depending on the capacity of the container 1, etc.

In the recess 41, each corner of the body 4, which is formed in the basic shape of a square tube, recesses into the inside of the container along the circumferential direction to form a bottom surface 41a that bridges between the widthwise center of one body side surface and the widthwise center of the other body side surface adjacent to each other via the corner (see particularly Figures 1, 6 and 7).

On the other hand, the truncated pyramid portion 40 is a portion formed in a truncated pyramid shape (a quadrangular truncated pyramid shape in the illustrated example) whose peripheral surface is inclined along the height direction, and in the truncated pyramid portion 40, the corner portions protrude outward from the container relative to the recessed portion 41 that recesses into the container, thereby forming the body portion 4 in the basic shape of a square tube (see particularly Figures 1 and 4).

In other words, the recess 41 is formed by recessing each corner of the body 4 into the container so that the portion connected to the peripheral surface of the upper and/or lower truncated pyramidal portion 40 remains in the center of the width of the side surface of the body.

As a result, the cross-sectional shape of the recess 41 with the bottom surface 41a as its side is roughly similar to the cross-sectional shape of the truncated pyramidal portion 40, and its apex (both circumferential ends of the bottom surface 41a) is located in the center of the width of each body side surface (see Figures 5, 6, and 7 in particular).

Note that FIG. 5 shows the cross-sectional shape of the truncated pyramidal portion 40 (end surface A-A in FIG. 3), and FIG. 6 shows the cross-sectional shape of the recessed portion 41 (end surface B-B in FIG. 3), and these cross-sectional shapes are superimposed in FIG. 7.

Here, "roughly similar" means that the cross-sectional shape of the truncated pyramidal portion 40 and the cross-sectional shape of the recessed portion 41 are similar enough to be recognized as having the same shape with the same number of sides and the same number of apexes.
In the illustrated example, the bottom surface portions 41a, 41a adjacent in the circumferential direction of the recessed portion 41 are formed so that the circumferential end portion of one bottom surface portion 41a and the circumferential end portion of the other bottom surface portion 41a intersect linearly along the height direction at the center portion that bisects the width of the side surface of the body portion, but a surface continuing to the circumferential surface of the truncated pyramidal portion 40 located above and/or below may be formed between the two. As a result, the cross-sectional shape of the recessed portion 41 has a shape with an apex chamfered in a C-chamfered shape, but even in such a case, it goes without saying that the cross-sectional shape is generally similar to that of the truncated pyramidal portion 40 in the illustrated example.
Therefore, in the present invention, "the center in the width direction of the side surface of the body" should not be interpreted as the exact center portion when the width of the side surface of the body is divided into two equal parts, but should be interpreted to include the above-mentioned aspects.

In this embodiment, the recesses 41 and the truncated pyramidal portions 40 are arranged alternately along the height direction, and at least in the center of the width of the side of the body, the recesses 41 are inclined along the height direction in the opposite direction to the circumferential surface of the truncated pyramidal portion 40 (see FIG. 8 in particular).

By doing this, according to this embodiment, even if the inside of the container becomes positive pressure, deformation due to the expansion of the body part 4 can be effectively suppressed. The reason for this will be explained in comparison with the conventional example.

When the container is subjected to positive pressure, as shown in Figure 10, a force acts on the sides of the body, causing it to bulge outward, and a force acts on the corners of the body, causing them to bend inward. As a result, the action of these forces causes the rectangular bottle to deform so that the cross section of the body becomes circular.

Furthermore, as in Patent Document 2, when a circular reinforcing rib is formed on the body of a rectangular bottle with a square cross-sectional shape, the cross-sectional shape of the area where the circular reinforcing rib is formed becomes circular. Therefore, when the inside of the container becomes positive pressure, the area where the circular reinforcing rib is formed is less likely to bulge outward from the container because the internal pressure (force) acts evenly on the entire reinforcing rib. On the other hand, when an internal pressure (force) that deforms the body so that it bulges outward from the container acts on a body with a square cross-sectional shape, the side of the body easily bulges and deforms, and the corners deform so as to be pulled inward from the container, making it impossible to maintain the rectangular shape of the body of the rectangular bottle (see Figure 11).

In contrast, in this embodiment, when the pressure inside the container becomes positive, a force acts on the bottom surface 41a of the recess 41 to deform it so that it bulges outward from the container, and a force acts on the top of the cross section of the recess 41, located in the center of the width of the side of the body, to deform it so that it is pulled inward from the container. As shown by the arrows in Figure 7, the action of these forces cancels out both the force that deforms the corners of the body 4 so that they are pulled inward from the container, and the force that deforms the side of the body so that it bulges outward from the container, and as a result, deformation due to the bulging of the body 4 can be suppressed.

Furthermore, in this embodiment, by inclining the recessed portion 41 and the truncated pyramidal portion 40 in opposite directions along the height direction at least in the center of the width direction of the side of the body, the perimeter at the intersection of the recessed portion 41 and the truncated pyramidal portion 40 can be shortened, so that even if the recessed portion 41 and the truncated pyramidal portion 40 are significantly deformed, the deformation is limited to approximately the extent shown by the two-dot chain line in Figure 8, and deformation of the side of the body can be more effectively suppressed.

In this way, in order to prevent the recessed portion 41 and the truncated pyramidal portion 40 from being significantly deformed outwardly from the container, the inclination angle θ ₁ of the recessed portion 41 along the height direction and the inclination angle θ ₀ of the truncated pyramidal portion 40 can be appropriately designed according to the magnitude of the force acting on these portions from inside the container, and are preferably set to, for example, 2 to 14°.

In the illustrated example, due to the shape of the bottom 5, the central portion of the width direction of the side of the torso in the lowest recessed portion 41 is not inclined along the height direction. In this embodiment, it is sufficient that the central portions of the width direction of the side of the torso in at least one pair of recessed portions 41 and truncated pyramidal portion 40 arranged adjacent to each other vertically along the height direction are inclined in opposite directions along the height direction.

In addition, from the viewpoint of suppressing deformation of the bottom surface 41a against the force acting on the bottom surface 41a of the recessed portion 41 from inside the container, it is preferable that the peripheral surface of the recessed portion 41, including the bottom surface 41a, is inclined along the height direction in the opposite direction to the peripheral surface of the truncated pyramid-shaped portion 40 over the entire circumference. Furthermore, from the same viewpoint, it is preferable that the peripheral surface of the truncated pyramid-shaped portion 40 is inclined in a fan-shaped manner along the height direction, and that the upper bottom surface 40a side of the truncated pyramid-shaped portion 40 at the corner portion bulges in an arc shape and is connected to the bottom surface 41a of the recessed portion 41 (see FIG. 4 in particular).

The present invention will be explained in more detail below with specific examples.

A cylindrical preform with a bottom was prepared by injection molding using a polyethylene terephthalate resin. The prepared preform was heated to soften it, and then set in a blow molding die. A container 1 was molded by biaxial stretch blow molding into the container shape shown in FIG. 1.
The height H of the container 1 was 206 mm, the width W was 60 mm, the diagonal width D was 71 mm, and the ratio of the diagonal width D to the width W (D/W) was 1.18.

Next, the container 1 was filled with carbonated water and sealed so that the pressure inside the container was 0.42 MPa at a temperature condition of 22° C., and the container was left to stand in a thermostatic chamber set at a temperature of 38° C. for 24 hours.
FIG. 9 shows image data corresponding to a front view obtained by 3D scanning the container 1 after being left to stand.
After the container 1 was allowed to stand, the maximum width W1 and maximum diagonal width D1 of the body 4 were measured. The rate of change in width [((W1-W)/W) x 100%] obtained from the measurements was -0.13%, the rate of change in diagonal width [((D1-D)/D) x 100%] was 0.23%, and the ratio (D1/W1) of the maximum diagonal width D1 to the maximum width W1 was 1.18.
From these results, it was confirmed that deformation due to the expansion of the body portion 4 was effectively suppressed.

The present invention has been described above with reference to preferred embodiments, but it goes without saying that the present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the present invention.

For example, in the above-described embodiment, an example was illustrated in which the peripheral surface of the truncated pyramidal portion 40 is inclined away from the central axis C as it moves downward along the height direction, and the peripheral surface of the recessed portion 41 is inclined toward the central axis C as it moves downward along the height direction, but each may be inclined in the opposite direction to the illustrated example.

In addition to being used for carbonated beverages, the synthetic resin container of the present invention can also be used for applications in which nitrogen gas or the like is sealed in together with the contents to create a positive pressure inside the container.

REFERENCE SIGNS LIST 1 Container 2 Mouth 3 Shoulder 4 Body 40 Pyramid-shaped portion 40a Upper bottom surface of the pyramid-shaped portion 41 Recessed portion 41a Bottom surface

Claims (4)

A synthetic resin container having a mouth, a shoulder, a body, and a bottom, which can be used for applications in which the inside of the container is made positive pressure after filling and sealing the contents,
The body portion is
Each corner of the body formed in a basic rectangular cylindrical shape has a recess that recesses inwardly along the circumferential direction of the container so as to form a bottom surface that bridges between the center in the width direction of one body side surface and the center in the width direction of the other body side surface that are adjacent to each other via the corner,
the corner portion protrudes outward from the container relative to the recessed portion, and the circumferential surface has a truncated pyramid shape that is inclined along a height direction;
The recessed portions and the truncated pyramidal portions are alternately arranged along a height direction,
A synthetic resin container, characterized in that at least at the center of the width direction of the side surface of the body, the bottom surface of the recess is inclined along the height direction in a direction opposite to the peripheral surface of the truncated pyramidal portion. The synthetic resin container according to claim 1, wherein the peripheral surface of the recessed portion, including the bottom surface portion, is inclined along the height direction in the opposite direction to the peripheral surface of the truncated pyramid portion over the entire circumference. The peripheral surface of the truncated pyramid portion is inclined in a widening manner along the height direction,
3. The synthetic resin container according to claim 1, wherein an upper bottom surface side of the truncated pyramidal portion at the corner portion bulges out in an arc shape and is connected to the bottom surface portion of the recessed portion. The synthetic resin container according to any one of claims 1 to 3, wherein the body is formed in a basic shape of a square cylinder when viewed from above.

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