Blow Molded Containers

Abstract

To provide a blow-molded container capable of suppressing expansion and deformation of a bottom part due to internal pressure increase.SOLUTION: A blow-molded container 1 includes: a cylindrical mouth part 10; a square-shaped trunk part 20 connected to the lower side of the mouth part 10; and a bottom part 30 for closing a lower end part of the trunk part 20. The bottom part 30 includes: a grounding part 31 extending along an outer peripheral edge of the bottom part 30; and a non-grounding part 32 formed by indenting a bottom wall toward the inside of the container 1 on the inside of the grounding part 31. The non-grounding part 32 has a flat surface 33 in parallel with a grounding surface of the grounding part 31, and the area of the flat surface 33 is equal to or greater than 15% and equal to or less than 40% of the area of the cross section of the trunk part 20.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a blow-molded container formed by blow molding. [Background technology]

[0002] Blow-molded bottle-shaped containers having a mouth, a body, and a bottom have been known as containers for accommodating various contents. Blow-molded containers can be formed, for example, by extrusion blow molding, in which an extruded cylindrical parison is blown.

[0003] The bottom of such a blow-molded container is closed by cutting off the parison with a split mold for blow molding during blow molding using a cylindrical parison, and then clamping and crimping the end (opening) of the parison with the mold. A pinch-off portion in the form of a vertical rib is formed along the parting line of the bottom at the closed portion of the bottom.

[0004] Patent document 1 discloses a blow-molded container having a ring-shaped grounding portion provided along the outer peripheral edge of the bottom, and a flat surface formed by recessing the bottom wall inside the grounding portion toward the inside of the container. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2019-081549 Summary of the Invention [Problem to be solved by the invention]

[0006] The container of Patent Document 1 can stand on its own by grounding the grounding portion. However, when a blow-molded container such as that of Patent Document 1 is filled with heated contents, or when the container is heat-sterilized after being filled with contents, the internal pressure of the container may increase, causing the recessed portion of the bottom to invert downward and bulge. As a result, for example, the pinch-off portion may come into contact with the placing surface, reducing the container's ability to stand on its own, which may adversely affect bottle transportation in filling equipment.

[0007] The present invention is intended to solve these problems, and its object is to provide a blow-molded container that can suppress bulging deformation of the bottom portion due to an increase in internal pressure. [Means for solving the problem]

[0008] The blow-molded container of the present invention is a blow-molded container comprising a cylindrical mouth portion, a rectangular body portion continuing below the mouth portion, and a bottom portion closing the lower end portion of the body portion, the bottom portion has a grounding portion extending along an outer peripheral edge of the bottom portion and a non-grounding portion formed by recessing the bottom wall toward the inside of the container inside the grounding portion, the non-grounded portion has a flat surface parallel to the ground surface of the grounded portion, The area of ​​the flat surface is characterized by being 15% or more and 40% or less of the area of ​​the cross section of the body portion.

[0009] In the blow-molded container of the present invention, the flat surface is preferably a substantially rectangular shape having four sides parallel to the four side surfaces that constitute the body portion.

[0010] In the blow-molded container of the present invention, the flat surface is preferably substantially square.

[0011] In the blow-molded container of the present invention, the vertical distance between the flat surface and the ground surface is preferably 2 mm or more and 4 mm or less.

[0012] In the blow-molded container of the present invention, it is preferable that the pinch-off portion provided on the bottom portion is located inside the outline of the flat surface. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide a blow-molded container that can suppress swelling deformation of the bottom portion due to an increase in internal pressure. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a front view of a blow-molded container according to one embodiment of the present invention. [Figure 2] FIG. 2 is a bottom view of the blow-molded container shown in FIG. [Figure 3] FIG. 2 is a side view of the blow-molded container shown in FIG. [Figure 4] 1 is a graph showing the results of a test to confirm the effect of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0015] The present invention will be described in more detail below with reference to the drawings. In this specification, claims, and abstract, the "upper" side refers to the side where the mouth 10 is located relative to the bottom 30 of the blow-molded container 1 shown in Fig. 1 (the upper side in Figs. 1 and 2), and the "lower" side refers to the opposite side (the lower side in Figs. 1 and 2). The axis O is the central axis of the blow-molded container 1.

[0016] Fig. 1 is a front view of a blow-molded container 1 of this embodiment, Fig. 2 is a bottom view, and Fig. 3 is a side view seen from the direction of parting line PL. As shown in Figs. 1 to 3, the blow-molded container 1 is a rectangular container having a cylindrical mouth 10, a rectangular body 20 continuing below the mouth 10, and a bottom 30 closing the lower end of the body 20. The interior of the blow-molded container 1 forms a storage space capable of storing various contents.

[0017] The mouth portion 10 in this example is cylindrical, with an upper end opening 11 at one end and a body portion 20 connected to the other end. A male thread 12 and a neck ring 13 are provided on the outer circumferential surface of the mouth portion 10.

[0018] For example, a lid that closes the upper opening 11, or a pouring cap having a pouring outlet for pouring the contents, can be attached to the mouth 10. In this case, the lid or pouring cap can be detachably attached to the mouth 10 by engaging the male thread 12 of the mouth 10 with a female thread provided on the lid or pouring cap. The shape of the mouth 10 is not limited to the illustrated example and can be modified as appropriate. For example, instead of the male thread 12, an annular fitting protrusion can be provided on the outer circumferential surface of the mouth 10, and a lid or pouring cap having an inward fitting protrusion that undercuts and engages with the fitting protrusion can be attached.

[0019] The body 20 has a shoulder 21 that connects to the lower end of the mouth 10 and gradually widens in diameter downward, and a body main body 22 that connects below the shoulder 21 and extends straight downward with approximately the same diameter. The bottom 30 connects to the lower end of the body main body 22. The body main body 22 extends linearly parallel to the axis O from the upper end that connects to the shoulder 21, and this linearly extending portion has the largest diameter of the body 20. Note that the diameter of the portion of the body main body 22 near the lower end that connects to the bottom 30 gradually decreases downward.

[0020] The body main body 22 has a rectangular cylindrical shape and is formed so that a cross section perpendicular to the axis O is approximately quadrangular. In this example, the cross section (cross section) perpendicular to the axis O is approximately square. Specifically, the body main body 22 has four main side surfaces 22a (side surfaces) that form the four sides of the square in cross section, and four flat connecting surfaces 22b provided at each corner. The main side surfaces 22a are approximately flat and, more specifically, are gently curved so as to bulge outward from the container. Note that the shape of the body 20 is not limited to the illustrated example as long as it is a rectangular cylindrical shape (square), and can be modified as appropriate. For example, the body 20 may have a shape in which the outline of the cross section is approximately rectangular having long sides and short sides, or a shape in which the outline of the cross section is a polygon other than a square. Furthermore, instead of the connecting surfaces 22b provided at the corners of the rectangle, arc-shaped curved portions that gently connect adjacent main side surfaces 22a may be provided, or bent portions that perpendicularly connect adjacent main side surfaces 22a may be provided. Furthermore, the blow-molded container 1 of this example is symmetrical in the front-to-back direction and left-to-right direction with respect to a plane that passes through the axis O and the parting line PL, but it may also be asymmetrical in the front-to-back direction or left-to-right direction.

[0021] The bottom 30 includes an annular grounding portion 31 extending along the outer periphery of the bottom 30 and a non-grounding portion 32 provided inside the grounding portion 31. The grounding portion 31 forms a flat grounding surface, and by grounding the grounding surface on a horizontal surface, the blow-molded container 1 can stand on its own. In this example, the grounding portion 31 is an approximately square ring, but this can be modified as appropriate depending on the outer shape of the bottom 30 and the shape of the flat surface 33, etc. Furthermore, the grounding portion 31 only needs to be annular as a whole, and may have a non-grounding region in part of its circumferential direction. For example, the grounding portion 31 in this example has recesses 31a at two locations located on extensions of the parting line PL of the bottom 30.

[0022] The bottom portion 30 is rectangular in shape to correspond to the shape of the trunk main body portion 22 (see FIG. 2). That is, as shown in FIG. 2, the bottom portion 30 in this example is formed so that the outline of its outer shape is approximately square when viewed from the bottom, and this outline has four main sides 30a and four chamfered connecting sides 30b. The shape of the bottom portion 30 can be changed as appropriate, similar to the trunk portion 20, and may be, for example, rectangular or another polygonal shape when viewed from the bottom.

[0023] The non-grounding portion 32 is a recess formed by depressing the bottom wall toward the mouth portion 10 (the interior side of the blow-molded container 1). The non-grounding portion 32 is located above the grounding portion 31, and is configured so as not to come into contact with the horizontal surface when the grounding surface of the grounding portion 31 is placed on the flat horizontal surface.

[0024] A flat surface 33 parallel to the ground surface of the ground portion 31 is provided in the center of the non-ground portion 32. The flat surface 33 is square in bottom view, and its contour line has four main sides 33a that are parallel to the four main side surfaces 22a that make up the trunk portion 20. The contour line of the flat surface 33 also has corners 33b at the intersections of adjacent main sides 33a, i.e., corners 33b that are provided in the same direction as the connecting surfaces 22b of the trunk main body portion 22. The corners 33b may be curved in an arc shape as in this example, or may be connected in a chamfered shape, or may be bent so that the main sides 33a intersect at right angles.

[0025] 2, the area of ​​the flat surface 33 is 15% or more and 40% or less of the area of ​​the cross section of the trunk portion 20. The area of ​​the cross section of the trunk portion 20 means the area of ​​the portion surrounded by the outline of the maximum diameter part of the trunk portion 20 (the maximum diameter part of the trunk main body portion 22), and in this example, means the area of ​​the portion surrounded by the outline of the trunk portion 20 shown in FIG.

[0026] A vertical rib-like pinch-off portion 34 is provided in the center of the flat surface 33 and extends linearly along the parting line PL of the bottom 30. In this example, the pinch-off portion 34 extends diagonally across the rectangular flat surface 33. Although the pinch-off portion 34 in this example extends linearly along the parting line PL, it may be partially curved or bent. As shown in FIG. 2, the pinch-off portion 34 in this example is formed inside the outline of the flat surface 33, but it may also extend outside the outline of the flat surface 33.

[0027] The flat surface 33 may have slight irregularities as long as it is a flat surface overall. The shape of the area of ​​the non-grounding portion 32 of the bottom 30 other than the flat surface 33 is not particularly limited.

[0028] The blow-molded container 1 described above can be an extrusion blow-molded container formed by, for example, extrusion blow molding. Extrusion blow molding can be a method in which a synthetic resin material is extruded through an extrusion die to form a cylindrical parison, which is then blow-molded using a blow-molding mold positioned below the die. The blow-molding mold is, for example, divided into two parts along a vertical parting plane including the axis O of the blow-molded container 1, and a pinch-off portion of the mold with a cutting blade is provided at the parting plane. Note that the blow-molded container 1 may also be formed by other blow molding methods, such as biaxially stretched blow molding. The synthetic resin material constituting the blow-molded container 1 can be selected from, for example, high-density polyethylene (HDPE), polypropylene (PP), polyethylene terephthalate (PET), etc. The blow-molded container 1 can have either a single-layer structure or a laminated structure. In the case of a laminated structure, for example, an adhesive resin layer can be provided between the HDPE layer and the ethylene-vinyl alcohol copolymer resin (EVOH) layer.

[0029] As described above, the blow-molded container 1 of this embodiment has a flat surface 33 on the non-ground-contact portion 32 of the bottom 30, and the area of ​​the flat surface 33 is set to 15% or more and 40% or less of the cross-sectional area of ​​the body 20. By setting the area of ​​the flat surface 33 to 15% or more of the cross-sectional area of ​​the body 20, the flat surface 33 does not become excessively small, ensuring moldability by blow molding. Furthermore, by setting the area to 40% or less, the strength of the non-ground-contact portion 32 of the bottom 30 can be appropriately increased. As a result, even if the internal pressure of the blow-molded container 1 increases due to hot filling or heating after filling, the non-ground-contact portion 32 of the bottom 30 is less likely to invert downward, and bulging deformation of the bottom 30 can be suppressed.

[0030] As described above, the blow-molded container 1 of this embodiment can suppress bulging deformation of the bottom 30 due to an increase in internal pressure. As a result, the blow-molded container 1 can be prevented from losing its self-standing ability, and can stand upright in a stable state, for example, during bottle transport in filling equipment. Furthermore, by suppressing bulging deformation of the bottom 30, positioning during decoration, such as attaching a decorative label to the outer surface of the blow-molded container 1, can be reliably performed using the bottom 30. Furthermore, by suppressing bulging deformation of the bottom 30, deterioration of the appearance of the blow-molded container 1 can be prevented.

[0031] Furthermore, in the blow-molded container 1 of this embodiment, it is preferable that the flat surface 33 has a substantially rectangular shape with four sides parallel to the four side surfaces (main side surfaces 22a) that make up the body 20. This configuration can further increase the strength of the non-grounding portion 32 of the bottom 30, and more reliably suppress swelling and deformation of the bottom 30. From the same perspective, it is more preferable that the flat surface 33 has a substantially square shape.

[0032] Furthermore, in the blow-molded container 1 of this embodiment, the area of ​​the flat surface 33 is preferably 25% to 35% of the area of ​​the cross section of the body portion 20. This configuration more reliably suppresses bulging deformation of the bottom portion 30. From the same viewpoint, it is most desirable that the area of ​​the flat surface 33 be 27% to 30% of the area of ​​the cross section of the body portion 20.

[0033] In the blow-molded container 1 of this embodiment, the distance H between the flat surface 33 and the contact surface of the contact portion 31 (the depth of the flat surface 33) is preferably 2 mm or more and 4 mm or less. By adopting such a configuration, it is possible to more reliably suppress the deterioration of the self-standing ability caused by the bulging deformation of the bottom portion 30.

[0034] In the blow-molded container 1 of this embodiment, it is preferable that the pinch-off portion 34 be located inside the contour line of the flat surface 33. With this configuration, the pinch-off portion 34 is less likely to protrude downward from the contact surface of the contact portion 31, and therefore, it is possible to more reliably prevent the deterioration of the self-supporting ability caused by the bulging deformation of the bottom portion 30. [Example]

[0035] The following describes a test performed to confirm the performance of the blow-molded container 1. The overall shape of the blow-molded container 1 used for the confirmation is rectangular, similar to that shown in Figs. 1 to 3, and the cross section of the body 20 is approximately square. The bottom 30 has a substantially square flat surface 33, as shown in Fig. 2. The blow-molded container 1 has a laminated structure in which an adhesive resin layer is provided between an inner HDPE layer and an outer EVOH layer.

[0036] For each of the blow-molded containers 1 of Examples 1-3 and the comparative example, the width W1 (length of one side of the square) of the body portion 20, the width W2 (length of one side of the square) of the flat surface 33 shown in FIG. 2, and the ratio (%) of the area of ​​the flat surface 33 to the area of ​​the cross section of the body portion 20 are shown in Table 1.

[0037] The blow-molded containers 1 of Examples 1-3 and the Comparative Example were filled (hot-filled) with contents at 85°C, and 60 seconds after filling was complete, they were cooled with a shower of water at approximately 25°C, and the amount of deformation of the bottom 30 was confirmed. The vertical distance H (depth of flat surface 33) from the contact surface of the bottom 30 to the flat surface 33 of each blow-molded container 1 before filling with the contents was measured, and the same distance H (depth of flat surface 33) after filling with the contents and cooling was measured, and the amount of change is shown in Table 1 and the graph in Figure 4. In Table 1, if the flat surface 33 deformed downward, the value is negative, and if it deformed upward, the value is positive.

[0038] [Table 1]

[0039] As shown in Table 1, in Examples 1-3, in which the area of ​​the flat surface 33 was 15% or more and 40% or less of the cross-sectional area of ​​the body portion 20, the downward deformation of the flat surface 33 was relatively small or did not occur. In Comparative Examples, in which the area of ​​the flat surface 33 was more than 40% of the cross-sectional area of ​​the body portion 20, the flat surface 33 underwent significant downward deformation. If the change in depth of the flat surface 33 were less than −0.3 mm (the flat surface 33 bulged downward by more than 0.3 mm), as in the Comparative Examples, this could adversely affect the alignment of the bottom 30 of the blow-molded container 1 during decoration, etc. However, in the blow-molded containers 1 of Examples 1-3, the change in depth was −0.3 or more, ensuring reliable alignment of the bottom 30 during decoration, etc. This confirms that the blow-molded containers 1 of Examples 1-3 were able to achieve the strength of the bottom 30 required for practical use. In Example 1, the flat surface 33 rose 0.2 mm upward, which was due to the decrease in the internal pressure of the blow-molded container 1 caused by the cooling of the contents after heating and filling.

[0040] Furthermore, in Examples 1 and 2, in which the area of ​​flat surface 33 was 27% or more and 30% or less of the cross-sectional area of ​​body portion 20, flat surface 33 did not deform downward, or deformed very little. That is, it was confirmed that the blow-molded containers 1 of Examples 1 and 2 had a more significant effect of improving the strength of bottom portion 30.

[0041] The present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the spirit of the present invention. For example, in the above-described embodiment, the flat surface 33 is described as being square in bottom view, but the present invention is not limited to this, and may be a quadrangle other than a square, or another polygon, or may be a circle, an ellipse, or the like. [Explanation of symbols]

[0042] 1: Blow molded container 10: Mouth 11:Top opening 12: Male thread 13: Neck ring 20: Torso 21:Shoulder 22: Body 22a: Main side (side) 22b: Connecting surface 30: Bottom 30a: Main side 30b: Connecting edge 31: Grounding part 31a: recess 32: Non-grounded part 33:Flat surface 34: Pinch-off section O: Axis line PL: Parting line

Claims

1. A blow-molded container having a cylindrical mouth, a rectangular body continuing below the mouth, and a bottom closing the lower end of the body, the bottom portion has a grounding portion extending along an outer peripheral edge of the bottom portion and a non-grounding portion formed by recessing the bottom wall toward the inside of the container inside the grounding portion, The ground contact portion is constituted only by a flat ground contact surface, the non-grounded portion has a flat surface parallel to the ground surface of the grounded portion, The area of ​​the flat surface is 15% or more and 40% or less of the area of ​​the cross section of the trunk portion, The flat surface has a substantially rectangular shape, the pinch-off portion provided on the bottom portion is located inside the outline of the flat surface, A blow-molded container, wherein the pinch-off portion extends diagonally across the flat surface.

2. The blow-molded container according to claim 1 , wherein the flat surface has four sides parallel to the four side surfaces that form the body portion.

3. 3. The blow-molded container according to claim 1, wherein the flat surface is substantially square.

4. The blow-molded container according to any one of claims 1 to 3, wherein the vertical distance between the flat surface and the ground surface is 2 mm or more and 4 mm or less.

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