JP7567198B2 - Plastic containers - Google Patents

Description

The present invention relates to a synthetic resin container.

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

When filling this type of container with liquid, it is known that the liquid is either filled at a high temperature (e.g., about 85°C) after being heat-sterilized (hot filling), which also serves as a sterilization process for the container, or the liquid is filled at room temperature in a controlled, aseptic environment after being sterilized with a chemical solution (aseptic filling), thereby suppressing the growth of bacteria after filling.

During hot filling, after the liquid is filled, the container is cooled to room temperature and then placed in a reduced pressure state. This is why containers are generally equipped with reduced pressure absorption panels arranged circumferentially around the body of the container. These panels deform inward as the container cools, reducing the volume of the container and absorbing the loss in internal pressure (see, for example, Patent Document 1).

On the other hand, with aseptic filling, the change in pressure inside the container immediately after filling can be ignored, but the moisture in the filled liquid may gradually permeate the container and leak out, or oxygen in the headspace may dissolve into the liquid, causing the pressure inside the container to decrease over time. For this reason, even in the case of aseptic filling, containers with a specified reduced pressure absorption performance are used as necessary.

JP 2001-206331 A

However, in many cases, a so-called shrink label made of a heat-shrinkable film material with the desired printing is attached to this type of container. In this case, if a vacuum absorption panel is arranged on the body of the container, the vacuum absorption panel will be visible through the shrink label, as if it is floating on the surface of the label.

As the use of this type of container has become more common in recent years, there is a growing demand for containers with distinctive design features to differentiate them from other products. For example, attempts have been made to give the container an appearance similar to that of a glass bottle. To achieve this, it is necessary to make the vacuum absorption panel less conspicuous.

In light of these circumstances, the inventors conducted extensive research to find a way to make the vacuum absorption panel attached to the body of the container less noticeable while still achieving the desired vacuum absorption performance when a shrink label or other label is attached, and as a result, they have completed the present invention.

The synthetic resin container according to the present invention is a synthetic resin container having a mouth, a shoulder, a body, and a bottom, and to which a label is attached, the synthetic resin container having a plurality of vacuum absorption panels arranged along a circumferential direction on a peripheral surface of the body, the vacuum absorption panel having a panel bottom located at the center of the width direction of the vacuum absorption panel, the cross section of which is formed into an arc shape convex toward the inside of the container, and a panel side portion located at both ends in the width direction of the panel bottom, the cross section of which is formed into a convex shape toward the outside of the container, both ends in the width direction of the panel side portion are connection portions between the panel bottom and the peripheral surface of the body, the radius of curvature in the cross section of the connection portion is made smaller than that of a main portion of the panel side portion excluding the connection portion, so that the panel bottom and the peripheral surface of the body portion are smoothly continuous along the circumferential direction, the central angle θ ₁ with respect to the width of the vacuum absorption panel is 13.5 to 33.1°, and the central angle θ ₂ with respect to the width of the panel bottom is 13.5 to 33.1°. ₁ , and the relationship Ra≧3Rd is established between the radius of curvature Ra of the main portion of the panel side in the cross section and the radius Rd of the body portion.

The synthetic resin container of the present invention allows the vacuum absorption panel arranged on the body of the container to be inconspicuous when a label such as a shrink label is attached, while still providing the desired vacuum absorption performance.

1 is a perspective 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. FIG. 3 is an end view taken along line AA in FIG. 2. FIG. 4 is an enlarged view of a main portion of FIG. 3 . FIG. 3 is a BB end view of FIG. 2. FIG. 3 is a CC end view of FIG. 2.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a perspective view showing an outline of a synthetic resin container according to this embodiment, and FIG. 2 is a front view of the same.
3 is an end view taken along line A-A in FIG. 2, FIG. 4 is an enlarged end view of a main portion in FIG. 3, FIG. 5 is an end view taken along line B-B in FIG. 2, and FIG. 6 is an end view taken along line C-C in FIG. 2, and in these end views, the thicknesses appearing on 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 cylindrically so that it has an appearance similar to that of a glass 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 liquid contents are poured, 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 example shown, the shoulder 3 is formed into a truncated cone shape, but the shape of the shoulder 3 is not limited to this. For example, it can also be formed into a so-called vine neck shape.

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.

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 2).
In addition, in FIG. 2, 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 is referred to as a transverse cross section.

A number of vacuum absorption panels 6 are arranged along the circumferential direction of the body 4. As the internal pressure of the container 1 decreases, they deform by bending inward, thereby reducing the volume inside the container and absorbing the decrease in internal pressure. There is no particular limit to the number of vacuum absorption panels 6, but it is preferable to arrange four vacuum absorption panels 6 at equal angular intervals along the circumferential direction so that each vacuum absorption panel 6 deforms evenly toward the central axis C of the container 1, preventing the container 1 from deforming indefinitely, and preventing the appearance of the container 1 from changing significantly when vacuum is absorbed.

Each of the vacuum absorption panels 6 arranged on the periphery of the body 4 is preferably formed with a symmetrical outline, as shown in the figure, based on a relatively narrow vertically elongated rectangular shape, with the four corners rounded to form an arc toward the center of the top and bottom ends.

The vacuum absorption panel 6 is formed to have a predetermined width _w1 , and is formed so that the central angle _θ1 relative to the width _w1 , i.e., the angle _θ1 between the lines connecting both end edges of the vacuum absorption panel 6 in the width direction and the central axis C in the cross section (see Figures 3 and 4), is 13.5 to 33.1°.
4 is an enlarged view of the area enclosed by the dashed line in FIG.

The vacuum absorption panel 6 also has a panel bottom 7 located in the widthwise center of the vacuum absorption panel 6 and having a cross-sectional shape formed in a convex arc toward the inside of the container, and panel side sections 8 located on both ends of the panel bottom 7 in the widthwise direction and having a cross-sectional shape formed in a convex arc toward the outside of the container.

When forming the vacuum absorption panel 6 in this manner, it is preferable that the depth d (see FIG. 4) of the vacuum absorption panel 6 relative to the peripheral surface of the body portion 4 is formed to a predetermined depth.

For example, the radius of curvature of the panel bottom 7 in the cross section is preferably (1/3)Rd to 3Rd with respect to the radius Rd of the body portion 4, and in terms of a specific numerical value taking into account a typical radius Rd of the body portion 4, it is preferably 20 to 1000 mm, and more preferably 30 to 100 mm.
Depending on the radius of curvature of the panel bottom 7 in cross section, the ratio d/ _w1 to the width _w1 of the vacuum absorption panel 6 is preferably 0.048 to 0.090, and more preferably 0.050 to 0.076.

3 to 6, the vacuum absorption panel 6 is preferably formed so that there is a smooth continuation between the panel bottom portion 7 and the peripheral surface of the body portion 4. In particular, it is preferably formed so that there is a smooth continuation along the circumferential direction.

In particular, as shown in Figures 3 and 4 , for example, by forming both ends in the width direction of the panel side portion 8 as connection portions 8b, 8c between the panel bottom portion 7 and the peripheral surface of the body portion 4, and making the radius of curvature of the connection portions 8b, 8c in cross section smaller than that of the main portion 8a excluding the connection portions 8b, 8c, the panel bottom portion 7 and the peripheral surface of the body portion 4 can be formed so as to be smoothly continuous along the circumferential direction (see Figures 3 and 4). In such an embodiment, the radius of curvature of the connection portions 8b, 8c in cross section is preferably 5 mm or more, and particularly preferably about 10 mm.
In addition, in Figures 3 and 4, the boundaries between the panel bottom 7, connecting portion 8b, main portion 8a, connecting portion 8c, and the peripheral surface of the body portion 4 are indicated by dashed lines extending from the central axis C of the container 1.

In this way, when a shrink label L is attached to the container 1, the vacuum absorption panel 6 is made less noticeable and an appearance similar to that of a glass bottle can be obtained. The shrink label L is attached by covering the container 1 with a heat-shrinkable film material with the desired printing in a cylindrical shape and heating it to shrink so that it adheres closely to the periphery of the container 1. In particular, since the shrink label L is usually attached to the body 4 while shrinking in the circumferential direction, by forming the space between the panel bottom 7 and the periphery of the body 4 so that it is smoothly continuous along the circumferential direction as described above, the vacuum absorption panel 6 is made relatively narrow within the above-mentioned range, and, together with the cross-sectional shape of the panel side portion 8 being convex toward the outside of the container, the outline of the vacuum absorption panel 6 can be effectively prevented from floating up on the surface of the shrink label L and being visible through it.

In FIG. 1, the shrink label L is shown by a dotted line, and is attached to the area from the lower end of the shoulder 3 to the bottom 5. However, there are no particular limitations on the area to which the shrink label L is attached, as long as the shrink label L is attached to the area including the vacuum absorption panel 6 and the vacuum absorption panel 6 is made inconspicuous, thereby achieving an appearance similar to that of a glass bottle.

In addition, this embodiment shows an example of a container used for aseptic filling, and it is required that a specified decompression absorption performance be exhibited when the pressure inside the container decreases over time as moisture from the filled liquid gradually permeates the container and leaks out, or as oxygen in the headspace dissolves into the liquid.

In order to meet such requirements, in this embodiment, the vacuum absorption panel 6 is formed so that the central angle θ ₂ with respect to the width w ₂ of the panel bottom 7, i.e., the angle θ ₂ between the lines connecting each of the widthwise end edges of the panel bottom 7 and the central axis C in the cross section (see Figures 3 and 4), is 28 to 60% of the central angle θ ₁ with respect to the width w ₁ of the vacuum absorption panel 6, and so that the relationship Ra ≧ 3Rd holds between the radius of curvature Ra of the main portion 8a of the panel side portion 8 in the cross section and the radius Rd of the body portion 4.
The significant figures of θ ₁ and θ ₂ are three digits, the significant figure of the percentage of θ ₂ relative to θ ₁ is two digits, and the significant figure of "3" in the above formula showing the relationship between Ra and Rd is one digit.

By doing this, it is possible to form the vacuum absorption panel 6 with a relatively narrow width within the aforementioned range while still achieving the desired vacuum absorption performance.

In order to ensure that the vacuum absorption panel 6 exhibits a desired vacuum absorption performance, it is preferable that the vertical length of the vacuum absorption panel 6 occupies 70% or more of the vertical length of the body portion 4.

As mentioned above, in order to make the vacuum absorption panel 6 less noticeable when the shrink label L is attached, it is preferable to form both ends of the panel side portion 8 in the width direction as connection portions 8b, 8c, so that the panel bottom portion 7 and the peripheral surface of the body portion 4 are smoothly continuous along the circumferential direction. However, when adopting such an embodiment, it is preferable to determine the proportion of the main portion 8a in the panel side portion 8, taking into account the balance with the vacuum absorption performance.

For example, it is preferable to determine the proportion of the main portion 8a in the panel side portion 8 so that the central angle θ ₄ with respect to the width w ₄ of the main portion 8a of the panel side portion 8, i.e., the angle θ ₄ (see Figures 3 and 4) between the lines connecting each of the widthwise end edges of the main portion 8a of the panel side portion 8 and the central axis C in the cross section, is 4.5 to 54.3% of the central angle θ ₃ with respect to the width w ₃ of the panel side portion 8, i.e., the angle θ ₃ (see Figures 3 and 4) between the lines connecting each of the widthwise end edges of the panel side portion 8 and the central axis C in the cross section.
The significant figures of θ ₃ and θ ₄ are three digits, and the significant figures of the percentage of θ ₄ relative to θ ₃ are two digits.

According to this embodiment, when a label such as a shrink label L is attached, the vacuum absorption panel 6 arranged on the body 4 can be made less noticeable while still achieving the desired vacuum absorption performance.

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

[Example 1]
A preform weighing about 20 g 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. The container 1 was molded by biaxial stretch blow molding into the container shape shown in Figs. 1 and 2.
Next, approximately 500 mL of water was filled at room temperature as the content liquid, and a lid was attached to the mouth 2 to seal the container. After that, a shrink label L was attached to the area extending from the lower end side of the shoulder 3 to the bottom 5, as shown in Figure 1.
The top plate of the lid was provided with a rubber stopper that could be pierced with an injection needle while maintaining the hermeticity of the inside of the container.

The height H of the container 1 was 190 mm, the radius Rd of the body 4 was 33 mm, and the average wall thickness of the container 1 calculated from the weight of the preform was about 0.29 mm.
The central angle θ ₁ relative to the width W ₁ of the vacuum absorption panel 6 was 33.1°, the central angle θ ₂ relative to the width W ₂ of the panel bottom 8 was 13.0° (θ ₁ × 39%), the radius of curvature Ra of the main portion 8 a of the panel side portion 8 in the transverse cross section was 300 mm (Rd × 9), the radius of curvature of the connection portions 8 b, c of the panel side portion 8 in the transverse cross section was 10 mm, and the radius of curvature Rb of the panel bottom 7 in the transverse cross section was 60 mm.

[Examples 2 and 3, Comparative Examples 1 to 3]
The container 1 was molded in the same manner as in Example 1, except that the central angle θ ₁ relative to the width W ₁ of the vacuum absorption panel 6, the central angle θ ₂ relative to the width W ₂ of the panel bottom 8, the radius of curvature Ra of the main portion 8a of the panel side portion 8 in the cross section, and the radius of curvature Rb of the panel bottom 7 in the cross section were each as shown in Table 1.
In Comparative Example 1, the vacuum absorption panel 6 was not provided.

[evaluation]
The rubber stopper on the lid was pierced with a syringe needle, and the syringe was used to extract water from the container, gradually reducing the pressure inside the container. Since the size of the container 1 used in this embodiment shows a volume reduction of about 7 mL over a one-year period, samples that did not show any irregular deformation even after 7 mL or more of water was extracted and the vacuum absorption panel 6 remained inconspicuous were marked with "Good", and samples that showed irregular deformation before reaching 7 mL were marked with "Poor". The evaluation results are shown in Table 1, along with the amount of water extracted when the container was deformed into an irregular shape.

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, the cavity surface of the blow molding die may be processed to have a knurled or mesh-like unevenness, and the surface of the container 1 may be decorated by transferring this. This makes it possible to make the vacuum absorption panel 6 disposed on the body 4 less noticeable when a label such as a shrink label L is attached.

1 Container 2 Mouth 3 Shoulder 4 Body 5 Bottom 6 Vacuum absorption panel 7 Panel bottom 8 Panel side L Shrink label w ₁ Width of vacuum absorption panel w ₂ Width of panel bottom w ₃ Width of panel side w ₄ Width of main part of panel side θ ₁ Central angle relative to width of vacuum absorption panel θ ₂ Central angle relative to width of panel bottom θ ₃ Central angle relative to width of panel side θ ₄ Central angle relative to width of main part of panel side d Depth of vacuum absorption panel relative to circumferential surface of body Ra Radius of curvature of main part of panel side in cross section Rd Radius of body

Claims (6)

A synthetic resin container having a mouth, a shoulder, a body, and a bottom , and to which a label is attached ,
A plurality of vacuum absorption panels are arranged along a circumferential direction on a circumferential surface of the body portion,
The vacuum absorption panel is
a panel bottom portion located at a center in a width direction of the vacuum absorption panel and having a cross-sectional shape formed in a convex arc toward the inside of the container;
a panel side portion located at both ends in a width direction of the panel bottom portion and having a cross-sectional shape formed to be convex toward the outside of the container,
both ends in the width direction of the panel side portion are respectively made to be connection portions between the panel bottom portion and the peripheral surface of the body portion, and a radius of curvature in a cross section of the connection portion is made smaller than that of a main portion of the panel side portion excluding the connection portions, so that the panel bottom portion and the peripheral surface of the body portion are smoothly continuous along the circumferential direction;
The central angle θ ₁ with respect to the width of the vacuum absorption panel is 13.5 to 33.1°,
A central angle θ ₂ with respect to the width of the panel bottom is 29 to 60% of the central angle θ ₁ ,
A synthetic resin container, wherein a radius of curvature Ra of a main portion of said panel side portion in cross section and a radius Rd of said body portion satisfy the relationship Ra≧3Rd. 2. The synthetic resin container according to claim 1, wherein a central angle θ ₄ of said panel side portion with respect to the width of the main portion is 4.5 to 54.3% of a central angle θ ₃ of said panel side portion with respect to the width of said panel side portion. The synthetic resin container according to claim 1 or 2, wherein the radius of curvature of the panel bottom in cross section is 20 to 1000 mm. 4. The synthetic resin container according to claim 1, wherein a ratio d/ _w1 of a depth d of the vacuum absorption panel relative to a peripheral surface of the body to a width _w1 of the vacuum absorption panel is 0.048 to 0.090. The synthetic resin container according to any one of claims 1 to 4, wherein the body is formed in a cylindrical shape, and the four vacuum absorption panels are arranged at equal angular intervals along the circumferential direction on the circumferential surface of the body. The synthetic resin container according to any one of claims 1 to 5, in which a shrink label is attached to an area including the vacuum absorption panel.

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