Synthetic resin container

Abstract

To suppress buckling deformation in a rectangular bottle starting near a boundary between a shoulder and a body on a corner part.SOLUTION: A body 4 is formed so as to include: body side surfaces 41; and chamfered body corners 42 each located between the body side surfaces 41. A shoulder part 3 is formed so as to include: shoulder side surfaces 31 which are located above the respective body side surfaces 41 of the body 4 and lateral widths of which become gradually narrower symmetrically to be continuous to the lower end of a mouth 2; and shoulder corners 32 located above the respective body corners 42 of body 4 and between the shoulder side surfaces 31. Recessed grooves 6 are each provided so as to have: a starting end 6a on the shoulder corner 32 side; and a terminating end 6b on the body corner 42 side.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a synthetic resin container. [Background technology]

[0002] Conventionally, synthetic resin containers have been used in a wide range of fields as containers for various beverages, seasonings, and the like, by producing a bottomed cylindrical preform using a thermoplastic resin such as polyethylene terephthalate by injection molding, compression molding, or the like, and then molding this preform into a bottle shape by biaxial stretch blow molding.

[0003] With regard to this type of synthetic resin container, after it has been filled, sealed and shipped, it is often the case that the containers are stacked in boxes during transportation and storage. During this process, it is necessary to prevent the containers from buckling or deforming due to the axial load, which would damage their commercial value (see, for example, Patent Documents 1 and 2).

[0004] The location that is most likely to become the starting point of buckling deformation depends on a balance between the overall shape of the container and the detailed shapes, but Patent Documents 1 and 2 attempt to suppress buckling deformation of the contact part or body part of containers known as round bottles. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2019-189267 A [Patent Document 2] JP 2019-189268 A Summary of the Invention [Problem to be solved by the invention]

[0006] The inventors noticed that in containers known as square bottles, the area near the boundary between the shoulder and body of the corner portion tends to be the starting point of buckling deformation, and after extensive research into how to suppress buckling deformation starting from this area, they completed the present invention. [Means for solving the problem]

[0007] The synthetic resin container according to the present invention is a synthetic resin container having a mouth, a shoulder, a body, and a bottom, the body including a body side surface and a body corner portion located between the body side surface portions, the shoulder including a shoulder side surface portion located above the body side surface portions of the body, a width of which gradually narrows symmetrically to the left and right and which is connected to the lower end of the mouth, and a shoulder corner portion located above the body corner portions of the body and between the shoulder side surface portions, and a groove portion having a starting end on the shoulder corner portion side and a terminal end on the body corner portion side is provided. The start end of the groove is located at the junction between the mouth and the shoulder. It is structured as follows. Effect of the Invention

[0008] According to the present invention, it is possible to suppress buckling deformation that originates near the boundary between the shoulder portion and the body portion of a corner portion of a rectangular bottle. [Brief description of the drawings]

[0009] [Figure 1] 1 is a perspective view showing an outline of a synthetic resin container according to an embodiment of the present invention. [Diagram 2] 1 is a front view showing an outline of a synthetic resin container according to an embodiment of the present invention. [Diagram 3] 1 is a plan view showing an outline of a synthetic resin container according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] 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, FIG. 2 is a front view of the same, and FIG. 3 is a plan view of the same.

[0011] The container 1 shown in these figures has a mouth 2, a shoulder 3, a body 4, and a bottom 5, and has a container shape generally referred to as a rectangular bottle, with the body 4 formed into a roughly rectangular cylindrical shape.

[0012] Such a container 1 can be manufactured by preparing a preform using a thermoplastic resin in a cylindrical shape with a bottom 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.

[0013] The thermoplastic resin used can 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 can be used, and in particular, ethylene terephthalate-based thermoplastic polyesters such as polyethylene terephthalate can 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. can 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.

[0014] The mouth 2 is a cylindrical portion that serves as an outlet for pouring the contents, and a screw thread 2a is provided on the side of the open end of the mouth 2 for attaching a lid (not shown). In addition, an annular neck ring 2b that protrudes outward in the circumferential direction is provided on the mouth portion 2. The mouth portion 2 includes a neck portion 2c that hangs down cylindrically with approximately the same diameter from just below the neck ring 2b, and the lower end of the mouth portion 2 is connected to a shoulder portion 3 that connects the mouth portion 2 and the body portion 4.

[0015] The body 4 occupies most of the height of the container 1 , and its upper end is connected to the shoulder 3 and its lower end is connected to the bottom 5 . Here, the height direction refers to the direction perpendicular to the horizontal plane when container 1 is placed upright on the horizontal plane with mouth 2 facing up, and defines the up-down, left-right and length-width directions of container 1 in this state (as shown in Figure 2).

[0016] In this embodiment, the body 4 is formed in a roughly angular cylindrical shape, and has a rectangular (square or rectangular; in the illustrated example, rectangular) cross-sectional shape (shape of a cross section perpendicular to the height direction) with the corners chamfered in an R-chamfered or C-chamfered shape, and is formed to include two opposing sets of body side portions 41 and chamfered body corner portions 42 located between each of the body side portions 41.

[0017] In the illustrated example, for convenience, the body side portion 41 located on the long side of the body 4 is given the symbol 41a, and the body side portion 41 located on the short side of the body 4 is given the symbol 41b, but these are collectively referred to as the body side portion 41.

[0018] In addition, a circumferential groove 40 extending in the circumferential direction is provided in a portion of the body 4 from the center in the height direction toward the bottom 5 for the purpose of increasing the rigidity of the portion. Although such a circumferential groove 40 may be omitted as appropriate, in the illustrated example, the upper body 4a and the lower body 4b, which are divided into upper and lower portions by the circumferential groove 40, are provided with vacuum absorption panels 45a, 45b on the side surface portions 41 of the body. The vacuum absorption panels 45a, 45b are intended to prevent uneven deformation of the container 1 caused by a decrease in internal pressure after the container is sealed when the container is filled with a heat-sterilized content liquid at a high temperature (hot filling) to also serve as a sterilization process for the container 1, and various panel shapes can be adopted according to the required vacuum absorption performance.

[0019] The shoulder portion 3 connecting such a body portion 4 and the mouth portion 2 formed in a cylindrical shape is formed so that its cross-sectional shape changes continuously from the cross-sectional shape of the body portion 4 (a square cross-sectional shape with chamfered corners) to the cross-sectional shape of the mouth portion 2 (a circular cross-sectional shape) from the body portion 4 side to the mouth portion 2 side. In this embodiment, the body portion 4 and the mouth portion 2 are connected by the shoulder portion 3 formed to include shoulder side portions 31 located above each body side portion 41 of the body portion 4 and connected to the lower end of the mouth portion 2 with their width gradually narrowing symmetrically, and shoulder corner portions 32 located above each body corner portion 42 of the body portion 4 and between the shoulder side portions 31, so that the cross-sectional shape of the shoulder portion 3 changes in this way.

[0020] In the container 1 thus formed, when a load applied in the axial direction is transmitted from the shoulder corner portion 32 of the shoulder portion 3 to the body corner portion 42 of the body portion 4, these function like pillars to receive the load, and at that time, the vicinity of the boundary between the shoulder portion 3 and the body portion 4 tends to be the starting point of buckling deformation. In this embodiment, by providing a groove portion 6 having a starting end 6a on the shoulder corner portion 32 side and a terminal end 6b on the body corner portion 42 side, it is possible to suppress buckling deformation that starts near the boundary between the shoulder portion 3 and the body portion 4 of the corner portions 32, 42 in such a rectangular bottle.

[0021] The shape of the groove portion 6 is not particularly limited, and may be, for example, a groove shape with a V-shaped cross section in which the groove side surfaces intersect at a linear groove bottom. However, in order to more effectively suppress buckling deformation and improve the load-bearing strength (longitudinal compressive strength) against a load applied in the axial direction, it is preferable that the groove portion 6 has a groove bottom of a predetermined width and a groove shape with a trapezoidal cross section in which the groove side surfaces rise from both widthwise edges of the groove bottom, as shown in the figure. Moreover, it is preferable that the recessed groove portion 6 is provided in a tapered shape toward a starting end 6a located on the shoulder corner portion 32 side.

[0022] In addition, if the groove 6 is provided so as to extend along the surface of the shoulder 3, the position of the start end 6a of the groove 6 is not particularly limited, but it is preferable that the start end 6a is located near the mouth 2 side, and it is particularly preferable that the start end 6a is located at the junction of the mouth 2 and the shoulder 3. If the groove 6 extends across the junction of the shoulder 3 and the body 4 to the body corner 42 side, the position of the end 6b of the groove 6 is not particularly limited, but it is preferable that it is located at the upper end side of the body corner 42. Furthermore, it is preferable that the groove 6 is provided so as to extend along the center of the shoulder corner 32 in the width direction and reach the center of the body corner 42 in the width direction. These modes can be appropriately selected so as to more effectively suppress buckling deformation starting from the boundary between the shoulder 3 and the body 4 of the corners 32, 42.

[0023] In the illustrated example, the shoulder 3 is provided with side edge grooves 7 along both side edges of the shoulder corner 32. This allows the shoulder 3 to be made thinner while still maintaining its strength, and this embodiment is also advantageous in suppressing buckling deformation that originates near the boundary between the shoulder 3 and the body 4 at the corners 32, 42. The body 4 is provided with vertical grooves 8 along both side edges of the body corners 42 so that the strength of the body 4 can be maintained while still maintaining its thickness, and these vertical grooves 8 are disposed on the extensions of the side edge grooves 7 provided in the shoulder 3.

[0024] With this configuration, when a load is applied to the container 1 in the axial direction, the load received by the corner portions 32, 42 can be transmitted through the side edge grooves 7 provided in the shoulder portion 3 and the vertical grooves 8 provided in the body portion 4 to the lower end side of the vertical grooves 8 (near the circumferential groove 40 in the illustrated example) without buckling deformation occurring along the way. As a result, the portion that can be the starting point of buckling deformation moves from near the boundary between the shoulder portion 3 and the body portion 4 to the portion on the lower end side of the vertical grooves 8. However, by appropriately adjusting the molding conditions when blow molding the container 1 and selectively forming the portion with a thick wall to make buckling deformation less likely to occur at that portion, it is possible to further improve the vertical compressive strength while forming the container 1 with a thinner wall overall. EXAMPLES

[0025] The present invention will now be described in more detail with reference to specific examples.

[0026] [Example 1] A preform weighing about 28 g was made by injection molding using a polyethylene terephthalate resin. The preform was heated to soften it, then set in a blow mold and molded into a container 1 by biaxial stretch blow molding so as to have the container shape shown in FIG. Container 1 was a 720 mL bottle with an average wall thickness of approximately 0.27 mm.

[0027] An axial load was applied to the obtained container 1 and the load was gradually increased. When the height of the container 1 was compressed by approximately 3.6 mm at a load of approximately 219 N, buckling displacement was observed near the boundary between the shoulder portion 3 and the body portion 4 of the corner portions 32, 42.

[0028] [Comparative Example 1] A container was formed so as to have the same container shape as in Example 1, except that the recessed groove portion 6 was not provided.

[0029] An axial load was applied to the resulting container and the load was gradually increased. When the height of the container was compressed by approximately 3.2 mm at a load of approximately 190 N, buckling displacement was observed near the boundary between the shoulder portion 3 and the body portion 4 of the corner portions 32, 42.

[0030] From these results, it was confirmed that according to the present invention, buckling deformation originating near the boundary between the shoulder portion 3 and the body portion 4 of the corner portions 32, 42 of a rectangular bottle can be suppressed, thereby improving the vertical compressive strength.

[0031] Although the present invention has been described above by showing preferred embodiments, it goes without saying that the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the present invention. [Explanation of symbols]

[0032] 1 container 2 Mouth 3 Shoulder 31 Shoulder side part 32 Shoulder corner 4. Torso 41 Side of the body 42 Body corner 5 Bottom 6 Concave groove part 6a Beginning 6b Termination 7 Side edge groove 8. Vertical groove

Claims

1. A synthetic resin container having a mouth, a shoulder, a body, and a bottom, The body portion includes body side portions and body corner portions located between the body side portions, The shoulder portion includes shoulder side portions located above the respective body side portions of the body portion, and connected to the lower end of the mouth portion by gradually narrowing its width symmetrically on the left and right, and shoulder corner portions located above the respective body corner portions of the body portion and between the respective shoulder side portions, a groove portion having a start end on the shoulder corner portion side and a terminal end on the body corner portion side is provided, A synthetic resin container, characterized in that the beginning of the groove portion is located at the junction of the mouth portion and the shoulder portion.

2. 2. The synthetic resin container according to claim 1, wherein the recessed groove portion has a trapezoidal cross section with groove side faces rising from both widthwise edges of the groove bottom.

3. 3. The synthetic resin container according to claim 1, wherein the groove is tapered toward its starting end.

4. 4. The synthetic resin container according to claim 1, wherein an end of the groove is located on an upper end side of the body corner portion.

5. The synthetic resin container according to any one of claims 1 to 4, wherein the groove portion extends along the widthwise center portion of the shoulder corner portion and reaches the widthwise center portion of the body corner portion.

6. The synthetic resin container according to any one of claims 1 to 5, wherein side edge grooves are provided along both side edges of the shoulder corner portion.

7. 7. The synthetic resin container according to claim 6, wherein vertical grooves are provided along both side edges of the body corners, and the vertical grooves are disposed on the extensions of the side edge grooves.

Images