Synthetic resin container lid

Abstract

To provide a synthetic resin container lid in which the required torque between a first torque and a second torque is sufficiently reduced. A plurality of fitting portions (40) each having a fitting surface (38) are formed at intervals in the circumferential direction, and the circumferential arrangement of the fitting portions (40) is appropriately set.

Description

Technical Field

[0001] The present invention relates to a synthetic resin container lid in a form in which locking means composed of a plurality of locking ridges extending in the circumferential direction or an annular locking ridge continuously extending in the circumferential direction is formed on the inner circumferential surface of the tamper-evident skirt portion of the skirt wall, and a fitting portion having a fitting surface with an inner diameter gradually increasing upward from the upper surface of the locking ridge when viewed in the vertical direction is formed.

Background Art

[0002] As is well known, as a container lid for a container formed of glass, synthetic resin or a thin metal plate and having a cylindrical mouth-neck portion with a male screw thread and a locking jaw portion located below the male screw thread disposed on the outer circumferential surface thereof, it comprises a circular top wall and a cylindrical skirt wall hanging down from the periphery of the top wall. A circumferentially extending breaking line composed of slits extending in the circumferential direction at intervals in the circumferential direction and bridging portions existing between such slits is formed in the skirt wall, and the skirt wall is partitioned into a main portion above the breaking line and a tamper-evident skirt portion below the breaking line. A synthetic resin container lid is widely used in practice. A female screw thread is formed on the inner circumferential surface of the main portion of the skirt wall, and locking means is formed on the inner circumferential surface of the tamper-evident skirt portion. The locking means is composed of a plurality of locking ridges protruding radially inward and extending in the circumferential direction or an annular locking ridge protruding radially inward and continuously extending in the circumferential direction.

[0003] When sealing the neck of a container filled with contents, the container lid is fitted onto the neck and rotated in the closing direction, screwing the female threads of the container lid into the male threads of the neck. Once the container lid is properly fitted to the neck, the locking mechanism of the container lid elastically overcomes the locking jaws of the neck and is positioned below them. When opening the neck and consuming the contents of the container, the container lid is rotated in the opening direction. In this way, the container lid rises relative to the neck as the male and female threads disengage. Once the container lid has risen somewhat, the locking mechanism of the container lid engages with the locking jaws of the neck, thereby preventing the bottom of the tamper evident from rising. As the container lid continues to rotate in the opening direction, the circumferential fracture lines formed on the skirt wall are broken, and the tamper-evident base of the skirt wall is separated from the main part (or, if an axial fracture line is formed on the tamper-evident base, the axial fracture line is broken, and the tamper-evident base unfolds from an endless annular shape to an ended band shape, and the tamper-evident base remains connected to the main part in a circumferential direction without being completely separated from it). As the container lid continues to rotate in the opening direction, the container lid (or the entire container lid including the tamper-evident base) is separated from the neck, leaving the tamper-evident base in place, and the neck is opened.

[0004] Patent Document 1 discloses that, in order to prevent the so-called "slip-off" where the entire container lid detaches from the neck of the container without the break line breaking, a fitting portion is formed on the inner circumferential surface of the tamper evident base, having an annular fitting surface that is continuous in the circumferential direction and whose radial inner diameter gradually increases upward from the upper surface of the locking projection. In a container lid in which such a fitting portion is formed, when the locking projection engages with the lower surface of the locking jaw of the neck, the fitting surface of the fitting portion is brought into close contact with the outer circumferential surface of the locking jaw, preventing the tamper evident base from elastically deforming or displacing, and thus preventing slip-off. However, it has been found that when a fitting portion is formed with the fitting surface described above, the required torque between the torque required when the container lid starts to rotate (generally called the "first torque") and the torque required when the break line is broken (generally called the "second torque") when the container lid is detached from the neck of the container is not sufficiently small, giving consumers an unpleasant feeling of resistance to the rotation of the container lid, a so-called dragging sensation.

[0005] Patent Document 2 below proposes making the mating surface of the mating part rough in order to reduce the required torque between the first torque and the second torque. Furthermore, Patent Document 3 below discloses defining a drainage path by omitting the mating part between a plurality of locking protrusions that constitute the locking means in order to allow the cleaning liquid sprayed onto the neck of the opening to flow down in order to wash away contents adhering to the neck of the opening when filling the container with contents. Omitting the mating part between the locking protrusions reduces the contact area between the locking jaw and the mating surface, thereby somewhat reducing the required torque between the first torque and the second torque. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2013-126881 [Patent Document 2] Japanese Patent Publication No. 2016-155589 [Patent Document 3] Japanese Patent Publication No. 2016-16900 [Overview of the project] [Problems that the invention aims to solve]

[0007] Therefore, while the container lids disclosed in Patent Documents 2 and 3 reduce the required torque between the first torque and the second torque somewhat compared to the container lid disclosed in Patent Document 1, our experience indicates that the reduction in the required torque between the first torque and the second torque is still insufficient, and it is not possible to reliably avoid giving consumers an unpleasant feeling, namely a so-called dragging sensation that resists the rotation of the container lid.

[0008] This invention was made in view of the above facts, and The technique The technical objective is to provide a novel and improved synthetic resin container lid in which the required torque between the first torque and the second torque is sufficiently reduced. 。 [Means for solving the problem]

[0009] Book As a result of diligent study, the inventors have formed multiple fitting portions having a fitting surface at intervals in the circumferential direction, and by appropriately setting the circumferential arrangement of such fitting portions, Writing skills Achieve technical challenges accomplish I discovered what I could do.

[0010] According to one aspect of the present invention, a synthetic resin container lid that achieves the above technical problem comprises a circular top wall and a cylindrical skirt wall hanging down from the periphery of the top wall, the skirt wall having a circumferentially extending fracture line formed by a plurality of circumferentially extending slits spaced apart in the circumferential direction and a plurality of bridging portions existing between the slits, the skirt wall being divided into a main portion above the fracture line and a tamper evident hem portion below the fracture line, a female thread formed on the inner circumferential surface of the main portion, and a locking means composed of a plurality of locking protrusions projecting radially inward and extending circumferentially being provided on the inner circumferential surface of the tamper evident hem portion. Each of the locking protrusions has an upper surface extending radially inward from the inner circumferential surface of the tamper evident base, a lower surface whose inner diameter gradually increases downward, and an inner surface located at the boundary between the upper and lower surfaces, wherein at both circumferential ends of the locking protrusion, the radially inward extension length of the upper surface gradually decreases toward both circumferential ends and / or the lower end of the lower surface is gradually displaced upward toward both circumferential ends. In a container lid made of synthetic resin, On the inner circumferential surface of the tamper evident base, multiple fitting portions are arranged at circumferential intervals for each of the multiple locking protrusions, with the fitting surface having a fitting surface in which the inner diameter gradually increases upward from the upper surface of the locking protrusion when viewed in the vertical direction. One fitting portion having a relatively large circumferential width is provided corresponding to each of the circumferential ends of the locking projection, and at least one fitting portion having a relatively small circumferential width is provided corresponding to the circumferential center of the locking projection. A container lid made of synthetic resin is provided, characterized in that the mating surface of the mating portion has a rough surface with an arithmetic mean roughness (Ra) of 2 to 20 μm as defined in JIS B0601. [Effects of the Invention]

[0012] A synthetic resin container provided by the above aspect of the present invention. On the lid In this configuration, instead of a fitting portion that extends continuously in the circumferential direction, multiple fitting portions are appropriately arranged at intervals in the circumferential direction. As a result, the contact area between the outer circumferential surface of the locking jaw portion of the jaw neck and the fitting surface of the fitting portion is significantly reduced, and consequently, the required torque between the first torque and the second torque is sufficiently reduced. [Brief explanation of the drawing]

[0013] [Figure 1] A front view showing a portion of a cross-sectional view of a preferred embodiment of a synthetic resin container lid constructed according to one aspect of the present invention. [Figure 2] Figure 1 shows a container lid and a magnified view of a portion of the neck of the container to which it is attached. [Figure 3]A view showing the tamper-evident skirt portion of the container lid shown in Fig. 1 unfolded. [Figure 4] A view showing the tamper-evident skirt portion of an example of a synthetic resin container lid unfolded.

Embodiments for Carrying Out the Invention

[0014] Hereinafter, referring to the accompanying drawings, a preferred embodiment of a synthetic resin container lid configured according to one aspect of the present invention will be described in further detail.

[0015] Referring to Fig. 1 for explanation, a container lid 2 that can be injection-molded or compression-molded from an appropriate synthetic resin such as polyethylene or polypropylene includes a circular top wall 4 and a cylindrical skirt wall 6 that hangs down from the periphery of the top wall 4. On the outer peripheral edge portion of the inner surface of the top wall 4, a relatively long cylindrical inner seal piece 8 that hangs downwards and a relatively short cylindrical outer seal piece 10 that hangs downwards are formed.

[0016] A breaking line 12 extending in the circumferential direction is formed on the skirt wall 6, and the skirt wall 6 is partitioned into a main portion 14 above the breaking line 12 and a tamper-evident skirt portion 16 below the breaking line 12. The breaking line 12 is composed of a plurality of slits (cut grooves) 18 extending in the circumferential direction at intervals in the circumferential direction and a plurality of bridging portions 20 existing between the slits 18, and the tamper-evident skirt portion 16 is connected to the main portion 14 via the plurality of bridging portions 20.

[0017] On the outer peripheral surface of the main portion 14 of the skirt wall 6, an anti-slip knurl 22 composed of uneven shapes alternately existing when viewed in the circumferential direction is formed. On the inner peripheral surface of the main portion 14 of the skirt wall​​​A locking mechanism 27 is provided on the inner circumferential surface of the tamper evident base portion 16. In the illustrated embodiment, the locking mechanism 27 is composed of a plurality of locking protrusions 28 (five in the illustrated embodiment) that project radially inward and extend circumferentially. Referring to Figure 2 along with Figure 1, the longitudinal cross-sectional shape of the main portion (excluding both ends) of each locking protrusion 28 is approximately a right triangle, and each locking protrusion 28 has an upper surface 30 that extends radially inward from the inner circumferential surface of the tamper evident base portion 16, a lower surface 32 whose inner diameter gradually increases downward, and an inner surface 34 located at the boundary between the upper surface 30 and the lower surface 32. Preferably, at both ends of the locking protrusion 28 in the circumferential direction, the radially inward extension length of the upper surface 30 is gradually reduced toward both ends of the circumferential direction and / or the lower end of the lower surface 32 is gradually displaced upward toward both ends of the circumferential direction. In the illustrated embodiment, the radially inward extension length of the upper surface 30 at both circumferential ends of the locking projection 28 is gradually reduced toward both circumferential ends (although not necessarily clearly shown in the illustration), and the lower end of the lower surface 32 is gradually displaced upward toward both circumferential ends.

[0019] On the inner peripheral surface of the tamper-evident skirt portion 16, an annular ridge 36 protruding radially inward is also formed. As can be clearly understood by referring to FIG. 2, the annular ridge 36 is provided at a portion that is connected to the upper surface 30 of the locking ridge 28 when viewed in the vertical direction. Continuing the explanation with reference to FIG. 3 together with FIG. 1, in the container lid of the present invention, on the inner peripheral surface of the tamper-evident skirt portion 16, a fitting portion 40 having a fitting surface 38 with an inner diameter that gradually increases upward from the upper surface 30 of the locking ridge 28 when viewed in the vertical direction is arranged at a plurality of positions spaced apart in the circumferential direction for each of the locking ridges 28. In the illustrated embodiment, one fitting portion 40a having a relatively large circumferential width is arranged corresponding to each of the circumferential ends of the locking ridge 28, and a plurality of (three in the illustrated embodiment) fitting portions 40b having a relatively small circumferential width are arranged corresponding to the central portion in the circumferential direction of the locking ridge 28. Focusing on one locking ridge 28, the circumferential intervals of each of the plurality of fitting portions 40 formed on its upper surface 30 are all equal. And the fitting surfaces 38 of the fitting portions 40 all extend upward from the upper surface of the locking ridge 28. Here, as shown in FIG. 3, if the circumferential width of the fitting portion 40a having a relatively large circumferential width is d1, the circumferential width of the fitting portion 40b having a relatively small circumferential width is d2, the circumferential interval of the plurality of fitting portions 40 formed on the upper surface 30 of one locking ridge 28 is d3, and the circumferential interval of the fitting portions 40a adjacent in the circumferential direction in two locking ridges 28 arranged adjacent in the circumferential direction is d4, then d1 = 3d2, d3 = 2d2, and d4 = d2 are set. The longitudinal cross-sectional shape of the fitting surface 38 is arcuate in all cases, and the fitting surface 38 and the inner surface of the annular ridge 36 are substantially flush. If desired, the longitudinal cross-sectional shape of the fitting surface 38 may be linear, and the inner surface of the annular ridge 36 may be located radially outside the fitting surface 38. This invention Furthermore, in [it], the fitting surface 38 has a rough surface with an arithmetic mean roughness (Ra) defined by JIS B0601 of 2 to 20 μm.

[0020] As shown in the illustrated embodiment, each of the locking protrusions 28 has an upper surface 30 extending radially inward from the inner circumferential surface of the tamper evident base 16, a lower surface 32 whose inner diameter gradually increases downward, and an inner surface 34 located at the boundary between the upper surface 30 and the lower surface 32, and at both circumferential ends of the locking protrusions 28, the radially inward extension length of the upper surface 30 is gradually reduced toward both circumferential ends and / or the lower end of the lower surface 32 is gradually displaced upward toward both circumferential ends, Although the rigidity of both ends of the locking projection 28 is reduced, if a fitting portion 40a with a relatively large circumferential width is provided corresponding to each of the circumferential ends of the locking projection 28, the forceful removal of both ends of the locking means 27 (locking projection 28) when removing the molded container lid 2 from the mold is mitigated by the presence of the fitting portion 40a with a relatively large circumferential width, and deformation of both ends of the locking projection 28 when removing the molded container lid from the mold is reliably avoided.

[0021] Figure 1 shows the container neck 42 along with the container lid 2. The container neck 42, which can be formed from an appropriate synthetic resin such as polyethylene terephthalate, glass, or a thin metal sheet, is cylindrical in shape overall, and a male thread 44 and a locking jaw 46 located below the male thread 44 are formed on the outer circumferential surface of the neck 42. The locking jaw 46 has an arc-shaped upper surface whose outer diameter gradually increases downward, a cylindrical outer circumferential surface, and a lower surface that extends substantially horizontally. A support ring 48 (such a support ring 48 is used for transporting the container, as is well known to those skilled in the art) is also provided on the outer circumferential surface of the neck 42, located below the locking jaw 46.

[0022] After filling the container with contents, before attaching the container lid 2 to the neck 42 of the container, a cleaning solution such as tap water is usually sprayed onto the outer surface of the neck 42 to wash away any contents adhering to it. After that, the container lid 2 is fitted onto the neck 42 and rotated in the closing rotation direction, clockwise when viewed from above in Figure 1, to screw the female threads 24 of the container lid 2 onto the male threads 44 of the neck 42. When the female threads 24 are screwed onto the male threads 44 to the state shown in Figure 1, the inner sealing piece 8 of the container lid 2 enters the neck 42 and makes close contact with the inner surface of the neck 42, and the outer sealing piece 10 comes into close contact with or near the outer surface of the neck 42, thus sealing the neck 42. The locking protrusions 28, located on the inner circumferential surface of the tamper evident base 16, elastically overcome the locking jaws 46 of the neck 42 (i.e., by elastic deformation or displacement of the tamper evident base 16) and are positioned below the locking jaws 46. In this state, as can be understood by referring to Figure 2 in conjunction with Figure 1, the area on the inner circumferential surface of the tamper evident base 16 above the locking protrusions 28 is in contact with or in close contact with the lower end of the outer circumferential surface of the locking jaws 46 of the neck 42. After the container lid 2 is attached to the neck 42 as required, a cleaning solution (such as tap water) is sprayed onto the container lid 2, followed by a drying gas (such as air) being sprayed onto the container lid to remove the cleaning water. The cleaning solution sprayed onto the neck 42 of the container and remaining on the neck 42 flows out from between the locking protrusions 28, which are spaced apart in the circumferential direction.

[0023] When opening the neck 42 to consume the contents, the container lid 2 is rotated in the opening direction, that is, counterclockwise when viewed from above in Figure 1. In this way, the threads of the male thread 44 and the female thread 24 are gradually released, and the tamper evident base 16, along with the main part 14, rises relative to the neck 42 as it rotates. As can be understood by referring to Figure 2, the inner surface of the fitting portion 40 provided on the bottom 16 of the tamper evident, that is, the fitting surface 38 whose inner diameter gradually increases upward from the upper surface of the locking projection 28, is brought into close contact with the lower end of the outer peripheral surface of the locking jaw portion 46 of the neck portion 42, thereby generating frictional resistance torque. However, in the container lid of the present invention, the fitting portion 40 does not extend continuously in the circumferential direction, but rather multiple fitting portions are appropriately arranged at intervals in the circumferential direction. As a result, the contact area between the outer peripheral surface of the locking jaw portion 46 of the neck portion 42 and the fitting surface 38 of the fitting portion 40 is significantly reduced, and consequently, the required torque between the first torque and the second torque is sufficiently reduced. When the container lid 2 is raised to a predetermined extent relative to the neck portion 42, the locking projection 28 is locked into the locking jaw portion 46, preventing the tamper evident base portion 16 from moving axially upward. As a result, stress is generated in the bridging portion 20 of the fracture line 12, causing the bridging portion 20 to fracture, and the tamper evident base portion 16 is separated from the main portion 14 of the skirt wall 6. When the break line 12 is broken, the inner surface of the fitting portion 40 provided on the tamper evident base portion 16, that is, the fitting surface 38 whose inner diameter gradually increases upward from the upper surface of the locking projection 28, comes into close contact with the lower end of the outer peripheral surface of the locking jaw portion 46 of the neck portion 42. As a result, elastic deformation or displacement of the tamper evident base portion 16 is suppressed, and it is sufficiently and reliably prevented from the locking projection 28 rising over the locking jaw portion 46 without the break line 12 being broken. After the break line 12 is broken, the tamper evident base portion 16 remains on the neck portion 42, and the top wall 4 and the main portion 14 of the skirt wall 6 of the container lid 2 are allowed to move freely upward in the axial direction with rotation and detach from the neck portion 42, thus opening the neck portion 42.If desired, an axial fracture line can be formed on the tamper evident base 16, and when the neck 42 of the container is opened, the axial fracture line is fractured, while a portion of the circumferential fracture line 12 remains intact, causing the tamper evident base 16 to unfold from an endless annular shape to an end-annular shape, and the entire container lid 2, together with the tamper evident base 16, to detach from the neck 42.

[0024] In the synthetic resin container lid shown in Figure 1, both circumferential sides of the fitting portion 40 extend linearly in the radial direction, and the fitting surface 38 and both circumferential sides of the fitting portion 40 are connected perpendicularly. However, the fitting surface 38 and both circumferential sides of the fitting portion 40 may be connected curvilinearly. By connecting the fitting surface 38 and both circumferential sides of the fitting portion 40 curvilinearly, when the container lid 2 is rotated in the opening direction, the fitting surface 38 is brought into close contact with the lower end of the outer peripheral surface of the locking jaw portion 46 of the mouth neck portion 42, and frictional resistance between the two is reduced when moving circumferentially relative to it. This frictional resistance can be further reduced by appropriately forming holes in the fitting surface 38. Furthermore, the upper ends of each of the multiple fitting portions 40 do not necessarily need to be aligned circumferentially when viewed vertically. Moreover, reinforcing portions with an inner diameter larger than the fitting portion 40 may be appropriately provided between circumferentially adjacent fitting portions 40.

[0025] next If Plastic container lid One example This will be explained with reference to Figure 4. Here, this The container lid and the container lids shown in Figures 1 to 3 are identical except for the locking means and fitting portion provided at the bottom of the tamper evident of the container lid shown in Figure 1, etc. Examples A general explanation of the container lid will be omitted, and only the locking mechanism and fitting part will be described.

[0026] As can be understood by comparing Figure 3 and Figure 4, the aboveIn the container lid, the locking means 27' is composed of an annular locking projection 28' that protrudes radially inward and extends continuously in the circumferential direction on the inner circumferential surface of the tamper evident base portion 16'. Even if the locking means 27' is composed of such an annular locking projection 28', by arranging multiple fitting portions 40' with fitting surfaces 38' that gradually increase in inner diameter from the upper surface of the locking means 27' upward at circumferential intervals on the inner circumferential surface of the tamper evident base portion 16', the contact area between the outer circumferential surface of the locking jaw portion of the mouth and the fitting surface of the fitting portion is significantly reduced, and as a result, the required torque between the first torque and the second torque is sufficiently reduced. [Explanation of symbols]

[0027] 2: Container lid 4: Top wall 6: Skirt Wall 12: Breaking line 14: Subject 16: Tamper-evident hem 18: Slit 20: Bridge section 24: Female thread 27:Latching means 28: Locking protrusion 38: Mating surface 40: Fitting part

Claims

[Claim 1] It comprises a circular top wall and a cylindrical skirt wall hanging down from the periphery of the top wall, and the skirt wall has a circumferentially extending fracture line formed by a plurality of circumferentially extending slits spaced apart in the circumferential direction and a plurality of bridging portions existing between the slits, and the skirt wall is divided into a main portion above the fracture line and a tamper evident hem portion below the fracture line, and a female thread is formed on the inner circumferential surface of the main portion, and the inner circumferential surface of the tamper evident hem portion has a radially inward projection and A container lid made of synthetic resin is provided with a locking mechanism consisting of a plurality of locking protrusions extending in the circumferential direction, each of which has an upper surface extending radially inward from the inner circumferential surface of the bottom of the tamper evident, a lower surface whose inner diameter gradually increases downward, and an inner surface located at the boundary between the upper surface and the lower surface, and at both circumferential ends of the locking protrusion, the radially inward extension length of the upper surface is gradually reduced toward both circumferential ends and / or the lower end of the lower surface is gradually displaced upward toward both circumferential ends, A synthetic resin container lid characterized in that, on the inner circumferential surface of the bottom of the tamper evident, multiple fitting portions are arranged at circumferential intervals for each of the multiple locking protrusions, with the fitting portion having a fitting surface whose inner diameter gradually increases upward from the upper surface of the locking protrusion when viewed in the vertical direction, and at least one fitting portion having a relatively large circumferential width is arranged corresponding to each of the circumferential ends of the locking protrusion, and at least one fitting portion having a relatively small circumferential width is arranged corresponding to the circumferential center of the locking protrusion, and the fitting surface of the fitting portion is a rough surface with an arithmetic mean roughness (Ra) of 2 to 20 μm as defined in JIS B0601.

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