Synthetic resin container lid

Abstract

To provide a novel synthetic resin container lid which clearly indicates, when a required operation for fraudulently opening a neck part 100 is carried out, that the operation has been performed.SOLUTION: In a synthetic resin container lid, (1) a weakened part 34 (a groove) is formed below engagement means 32 in a tamper-evident skirt part 22 when viewed in a vertical direction or (2) the groove 34 extending in a circumferential direction is provided on an inner peripheral surface or an outer peripheral surface of the tamper-evident skirt part 22. A vertical cross sectional shape of the groove 34 is formed in a triangle shape having an upper side 36 and a lower side 40 which extends downward inclining in a radial direction.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] As an example of a synthetic resin container lid for a beverage container having a cylindrical neck portion on whose outer circumferential surface a male thread and a locking jaw portion located below the male thread are arranged, the following Patent Document 1 shows a synthetic resin container lid having a circular top wall and a cylindrical skirt wall hanging down from the periphery of the top wall, with a breakable line extending circumferentially on the skirt wall, the skirt wall being divided into a main portion above the breakable line and a tamper-evident hem portion below, with a female thread on the inner circumferential surface of the main portion and a locking means and a circular groove extending circumferentially above the locking means on the inner circumferential surface of the tamper-evident hem portion.

[0003] The synthetic resin container lid described above is attached to the neck of a container by fitting it over the neck and rotating it in the closing direction, i.e., clockwise as viewed from above, and threading the female thread of the lid onto the male thread of the neck. The locking means formed on the inner peripheral surface of the tamper-evident skirt elastically overcomes the locking jaws of the neck and is positioned below them. When opening the neck of the container to consume the contents of the container, the container lid is rotated in the opening direction, i.e., counterclockwise as viewed from above. As a result, the female thread gradually disengages from the male thread, and the main portions of the top wall and skirt wall of the container lid attempt to rise as the container lid rotates in the opening direction, but the tamper-evident bottom portion is prevented from rising by the locking means formed on its inner surface locking with the locking jaws of the neck portion, thus generating stress in the breakable line, causing it to break and separating the tamper-evident bottom portion from the main portion of the skirt wall. After this, the tamper-evident bottom portion remains in the neck portion, and the main portions of the top wall and skirt wall are free to rise as the container lid rotates in the opening direction and separate from the neck portion, thereby opening the neck portion. The fact that the tamper-evident bottom portion remains in the neck portion clearly indicates that the required opening operation has been performed on the container lid.

[0004] Furthermore, although it is not necessarily a synthetic resin container lid, Patent Document 2 listed below discloses a metal container lid which has a circular top wall and a cylindrical skirt wall hanging down from the periphery of the top wall, the skirt wall having a breakable line extending circumferentially, the skirt wall being divided into a main portion above the breakable line and a tamper-evident bottom portion below, the inner surface of the main portion having a female thread, and the lower part of the tamper-evident bottom portion having a locking portion formed by deforming the inner and outer surfaces radially inward, the inner surface of the locking portion having a weakened portion which is a circular groove extending circumferentially. To manufacture such a metal container lid, a metal sheet is first machined to form a preformed body having a circular top wall and a cylindrical skirt wall that hangs down from the periphery of the top wall, with a circumferentially extending breakable line formed in the skirt wall and a circumferentially extending annular groove formed below the breakable line on the inner peripheral surface of the skirt wall. This preformed body is then fitted onto the neck of a container and further machined. This machining includes a step of crimping the lower end of the skirt wall into a locking jaw of the neck to form a locking portion. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 5918450 [Patent Document 2] Patent No. 6061323 Summary of the Invention [Problem to be solved by the invention]

[0006] According to the inventor's experience, the synthetic resin container lid shown in the above Patent Document 1 has a problem to be solved: by engaging the end of the tamper-evident bottom portion with a finger or an appropriate tool and rotating the container lid in the opening rotation direction while displacing the end of the tamper-evident bottom portion radially outward, the entire container lid can be separated from the neck portion without breaking the breakable line, thereby tampering with the neck portion. The metal container lid shown in the above Patent Document 2 has a similar problem, but because a weakened portion consisting of a groove is formed on the inner surface of the engaging portion of the tamper-evident bottom portion, when the required operation to tamper-open the neck portion is performed as described above, the weakened portion breaks, etc., making it clear that the operation has been performed. However, the container lid disclosed in Patent Document 2 is made of metal and manufactured as described above, i.e., the preform already has a weakened portion formed therein, and the required machining is performed to form the locking portion, which raises the risk of the weakened portion breaking when the required machining is performed, particularly when the lower end of the skirt wall of the preform is crimped onto the locking jaw of the mouth and neck.

[0007] The present invention was made in consideration of the above facts, and its main technical object is to provide a new and improved synthetic resin container lid that does not require post-processing while fitted over the mouth and neck of a container, and that, when the required operations for tampering with the mouth and neck are performed as described above, clearly indicates that such operations have been performed. [Means for solving the problem]

[0008] After extensive research, the inventors have found that the above-mentioned main technical problem can be solved by (1) forming a weakened portion below the locking means at the bottom of the tamper-evident element when viewed in the vertical direction, or (2) providing a weakened portion consisting of a groove extending circumferentially on the inner or outer surface of the bottom of the tamper-evident element, and making the cross-sectional shape of the groove a triangle having an upper side and a lower side that extends radially and inclined downward.

[0009] That is, according to a first aspect of the present invention, there is provided a synthetic resin container lid that solves the above-mentioned main technical problem, comprising a circular top wall and a cylindrical skirt wall that hangs down from the periphery of the top wall, A synthetic resin container lid, wherein the skirt wall is provided with a circumferentially extending breakable line, the skirt wall is divided into a main portion above the breakable line and a tamper-evident bottom portion below the breakable line, the main portion has an internal thread on the inner peripheral surface, and the tamper-evident bottom portion has a locking means on the inner peripheral surface, The synthetic resin container lid is characterized in that a weakened portion is formed below the locking means when viewed in the vertical direction at the tamper-evident bottom portion.

[0010] In the first aspect of the present invention, the weakened portions are preferably a plurality of circumferentially extending arc-shaped or annular grooves spaced apart from one another. Furthermore, the longitudinal cross-sectional shape of the grooves is preferably a triangle having an upper side and a lower side that extends radially downward at an inclination. Furthermore, it is preferable that the upper side extends horizontally and the lower side extends linearly, and that the corners connecting the upper and lower sides are curved.

[0011] According to a second aspect of the present invention, there is provided a synthetic resin container lid that solves the above-mentioned main technical problem, comprising a circular top wall and a cylindrical skirt wall that hangs down from the periphery of the top wall, A synthetic resin container lid, wherein the skirt wall is provided with a circumferentially extending breakable line, the skirt wall is divided into a main portion above the breakable line and a tamper-evident bottom portion below the breakable line, the main portion has an internal thread on the inner peripheral surface, and the tamper-evident bottom portion has a locking means on the inner peripheral surface, A synthetic resin container lid is provided, characterized in that a weakened portion is formed on the inner or outer peripheral surface of the tamper-evident bottom portion, and the weakened portion is a plurality of arc-shaped or annular grooves extending circumferentially at intervals in the circumferential direction, and the cross-sectional shape of the groove is a triangle having an upper side and a lower side extending radially downward at an inclination.

[0012] In the second aspect of the present invention, it is preferable that the upper side extends horizontally and the lower side extends linearly, and that the corner connecting the upper side and the lower side is curved. [Effects of the Invention]

[0013] Even in the first aspect of the present invention, there is still a risk that the entire container lid may be detached from the neck portion without breaking the breakable line, thereby tampering with the neck portion by engaging the end of the tamper-evident bottom portion with a finger or an appropriate tool and rotating the container lid in the opening rotation direction while displacing the end of the tamper-evident bottom portion radially outward. However, in the first aspect of the present invention, when the end of the tamper-evident bottom portion is displaced radially outward as described above, due to the weakened portion formed below the locking means in the tamper-evident bottom portion when viewed in the up-down direction, the end of the tamper-evident bottom portion easily plastically deforms from the weakened portion as a base point, or the weakened portion easily whitens, making it clear that the neck portion has been tamper-opened. In addition, the container lid shown in Patent Document 1 also has a circumferentially extending groove formed on the inner or outer peripheral surface of the tamper-evident bottom, but since this groove is formed above the locking means when viewed from the top-bottom direction, even if a finger or tool is locked on the end of the tamper-evident bottom, the finger or tool will not directly act on the groove. Therefore, the abuse of the groove by a finger or tool is insufficient, and the end of the tamper-evident bottom does not undergo plastic deformation starting from the groove, or the part of the tamper-evident bottom corresponding to the groove does not whiten. Furthermore, the longitudinal cross-sectional shape of the groove is unknown.

[0014] Even in the second aspect of the present invention, when the end of the tamper-evident bottom portion is displaced radially outward as described above, due to the triangular cross-sectional shape of the groove formed on the inner or outer peripheral surface of the tamper-evident bottom portion, the tamper-evident bottom portion easily undergoes plastic deformation starting from the corner of the groove, or the portion of the tamper-evident bottom portion corresponding to the corner of the groove easily whitens, making it clear that the neck portion has been tamper-opened.

[0015] The container closures constructed according to the first and second aspects of the present invention are both made of synthetic resin, and the locking means is formed on the inner peripheral surface of the tamper-evident skirt during molding, i.e., simultaneously with molding. In other words, the locking means is not formed by post-processing after the container closure is fitted onto the neck of the container, so the weakened portion will not break when the container closure is attached to the neck. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a front view showing a partial cross section of a synthetic resin container lid constructed according to the present invention; [Figure 2] 2 is an enlarged view of a vertical cross section of a weakened portion of the container lid shown in FIG. 1. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0017] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in more detail with reference to the accompanying drawings showing preferred embodiments of a synthetic resin container lid constructed according to the present invention.

[0018] 1, a container lid 2, which can be injection molded or compression molded from a suitable synthetic resin such as polyethylene or polypropylene, has a circular top wall 4 and a cylindrical skirt wall 6 depending from the outer periphery of the top wall 4. A relatively long cylindrical inner seal piece 8 and a relatively short cylindrical outer seal piece 10 depending downward are formed on the inner periphery of the top wall 4. Furthermore, a relatively small annular ridge 12 is formed between the inner seal piece 8 and the outer seal piece 10.

[0019] The skirt wall 6 has a relatively thick upper portion 14 and a relatively thin lower portion 16. A circumferentially extending breakable line 18 is formed at the upper end of the thin lower portion 16, and the skirt wall 6 is divided into a main portion 20 above the breakable line 18 and a tamper-evident skirt portion 22 below the breakable line 18. In the illustrated embodiment, the breakable line 18 is composed of a plurality of circumferentially extending slits (kerfs) 24 and a plurality of bridging portions 26 remaining between the slits 24, and the tamper-evident skirt portion 22 is connected to the main portion 20 via the plurality of bridging portions 26.

[0020] The outer peripheral surface of the main portion 20 of the skirt wall 6 is formed with anti-slip knurling 28, consisting of alternating concave and convex shapes when viewed in the circumferential direction. The inner peripheral surface of the main portion 20 is formed with an internal thread 30. In the illustrated embodiment, the internal thread 30 is composed of a plurality of internal thread portions 31 spaced apart in the circumferential direction. The inner peripheral surface of the tamper-evident skirt portion 22 of the skirt wall 6 is formed with a locking means 32. In the illustrated embodiment, the locking means 32 is a plurality of locking ridges spaced apart in the circumferential direction and extending in the circumferential direction. If desired, the locking means 32 may be a ring-shaped locking ridge extending in the circumferential direction or a flap extending radially inward. The inner peripheral surface of the tamper-evident skirt portion 22 is further formed with a ring-shaped groove 34 extending in the circumferential direction below the locking means 32. In the illustrated embodiment, the groove 34 constitutes a weakened portion. As can be seen from FIG. 2 , the groove 34 has a triangular cross-sectional shape, including an upper edge 36 extending substantially horizontally, a corner 38 curved downward from the radially outer end of the upper edge 36 toward the radially outer side, and a lower edge 40 extending linearly downward from the lower end of the corner 38, sloping radially inward. If desired, the corner 38 may be sharply pointed. The upper edge 36 is preferably shorter than the lower edge 40; that is, the corner 38 is preferably positioned above the center height of the vertical width of the opening of the groove 34. This is because, when the inner molding die is released during molding of the container lid 2, mold release failure due to resistance to catching between the container lid 2 and the inner molding die is suppressed. The weakened portion, which may be the groove 34, may also be formed on the outer peripheral surface of the tamper-evident skirt 22. Even when the weakened portion is formed on the outer peripheral surface of the tamper-evident skirt portion 22, it is preferable that the weakened portion be located below the locking means 32 when viewed in the vertical direction.

[0021] 1 also shows, by a two-dot chain line, the container lid 2 and the neck of the container to which the lid 2 is attached. The neck 100 of the container, which can be made of a suitable synthetic resin such as polyethylene terephthalate or glass, is cylindrical overall and has an open top. The outer periphery of the neck 100 is formed with a male thread 102, a locking jaw 104 located below the male thread 102, and a support ring 106 located further below the locking jaw 104. As is well known to those skilled in the art, the support ring 106 is used when transporting the container.

[0022] When fitting the container lid 2 to the neck portion 100 to seal it after filling the container with contents such as a soft drink, the container lid 2 is fitted over the neck portion 100 and rotated in the closing direction, i.e., clockwise as viewed from above in Fig. 1. Thus, the female thread 30 of the container lid 2 is threadedly engaged with the male thread 102 of the neck portion 100, and the container lid 2 is lowered relative to the neck portion 100 as it rotates. When the container lid 2 is lowered to the required position, i.e., the position shown in Fig. 1, the locking means 32 formed on the inner peripheral surface of the tamper-evident skirt 22 elastically overcomes the locking jaws 104 of the neck portion 100 and is positioned below them. Then, the annular protrusion 12 formed on the inner surface of the top wall 4 of the container lid 2 abuts against the top surface of the mouth and neck portion 100, and the inner seal piece 8 and the outer seal piece 10 formed on the inner surface of the top wall 4 of the container lid 2 are brought into close contact or abutment with the inner and outer peripheral surfaces of the mouth and neck portion 100, respectively, thereby sealing the mouth and neck portion 100.

[0023] Here, with a container lid constructed according to the present invention, there is a risk that the entire container lid may be detached from the neck portion without breaking the breakable line 18, thereby tampering with the neck portion, by engaging the end of the tamper-evident bottom portion 22 with a finger or an appropriate tool and rotating the container lid in the opening rotation direction while displacing the end of the tamper-evident bottom portion 22 radially outward. However, with a container lid constructed according to the present invention, when the end of the tamper-evident bottom portion 22 is displaced radially outward as described above, the weakened portion consisting of the groove 34 is formed on the end of the inner peripheral surface (or outer peripheral surface) of the tamper-evident bottom portion 22 below the locking means 32 when viewed in the vertical direction, and therefore the end of the tamper-evident bottom portion 22 easily undergoes plastic deformation starting from the groove 34 or the groove 34 easily whitens, making it clear that the neck portion 100 has been tamper-opened. When the container lid 2 is colored other than white or is transparent, the whitening is more pronounced, and the visibility is further improved.

[0024] Furthermore, in a container lid constructed according to the present invention, when the end of the tamper-evident hem 22 is displaced radially outward as described above, due to the triangular cross-sectional shape of the groove 34 formed on the inner or outer surface of the tamper-evident hem 22, the tamper-evident hem 22 easily undergoes plastic deformation starting from the corner 38 of the groove 34, or the portion of the tamper-evident hem 22 corresponding to the corner 38 of the groove 34 easily whitens, making it clear that the opening and neck portion 100 has been tamper-opened.

[0025] When opening the neck opening 100 to consume the contents, the container lid 2 is rotated in the opening direction, i.e., counterclockwise as viewed from above in Figure 2. As a result, the male thread 102 and the female thread 30 gradually disengage from each other, and the main portion 20 of the skirt wall 6 moves axially upward as the lid 2 is rotated. Meanwhile, the tamper-evident skirt 22 is prevented from moving axially upward because the locking means 32 is locked by the locking jaw 104. This generates stress in the bridging portion 26 of the breakable line 18, causing the bridging portion 26 to break and the tamper-evident skirt 22 to be separated from the main portion 20 of the skirt wall 6. Thereafter, the top wall 4 of the container lid 2 and the main part 20 of the skirt wall 6 are rotated and freely moved upward in the axial direction, leaving the tamper-evident bottom part 22 remaining on the mouth and neck part 100, and are separated from the mouth and neck part 100, thus opening the mouth and neck part 100. The tamper-evident bottom part 22 of the skirt wall 6 remaining on the mouth and neck part 100 clearly indicates that the mouth and neck part 100 has been opened.

[0026] Here, by setting the breaking strength of the portion of the tamper-evident bottom 22 where the groove 34 is formed to be equal to or lower than the breaking strength of the bridging portion 26, the lower end of the tamper-evident bottom 22 of the skirt wall 6 is more easily plastically deformed starting from the groove 34, which is a weakened portion, or the weakened portion is more easily whitened, making it more obvious that the neck portion has been tampered with. Furthermore, when the locking means 32 is locked with the locking jaw 104, stress is applied to the locking means 32, and this stress is also transmitted to the groove 34, which is a weakened portion, so that the whitening of the portion where the groove 34, which is a weakened portion, is formed also makes it clear that the neck portion 100 has been opened.

[0027] The synthetic resin container lid constructed according to the present invention has been described in detail above with reference to the accompanying drawings, but the present invention is not limited to the above-described embodiment, and appropriate modifications and changes are possible within the scope of the present invention. For example, in the illustrated embodiment, the weakened portion is a circular groove extending in the circumferential direction, but the weakened portion does not necessarily have to be a groove and may be thin-walled, for example. If the weakened portion is a groove and the cross-sectional shape of the groove is triangular, the groove may be formed at any vertical position of the tamper-evident bottom portion 22. [Explanation of symbols]

[0028] 2: Container lid 4: Top wall 6: Skirt wall 18: Breakable line 20: Main section 22: Tamper evident bottom 30:Female thread 32:Latching means 34: Weakened part (groove) 36: Upper edge (in the longitudinal cross-sectional shape of the groove) 40: Lower edge (in the longitudinal cross-sectional shape of the groove)

Claims

1. The container has a circular top wall and a cylindrical skirt wall that hangs down from the periphery of the top wall, A synthetic resin container lid, wherein the skirt wall is provided with a circumferentially extending breakable line, the skirt wall is divided into a main portion above the breakable line and a tamper-evident bottom portion below the breakable line, the main portion has an internal thread on the inner peripheral surface, and the tamper-evident bottom portion has a locking means on the inner peripheral surface, A synthetic resin container lid, characterized in that a weakened portion is formed below the locking means when viewed in the vertical direction at the tamper-evident bottom portion.

2. 2. The synthetic resin container closure according to claim 1, wherein said weakened portions are a plurality of arc-shaped grooves extending circumferentially at intervals in the circumferential direction or annular grooves extending circumferentially.

3. 3. The synthetic resin container lid according to claim 2, wherein the longitudinal cross section of the groove is a triangle having an upper side and a lower side extending downward at an angle in the radial direction.

4. 4. The synthetic resin container lid according to claim 3, wherein the upper side extends horizontally and the lower side extends linearly, and the corner connecting the upper side and the lower side is curved.

5. The container has a circular top wall and a cylindrical skirt wall that hangs down from the periphery of the top wall, A synthetic resin container lid, wherein the skirt wall is provided with a circumferentially extending breakable line, the skirt wall is divided into a main portion above the breakable line and a tamper-evident bottom portion below the breakable line, the main portion has an internal thread on the inner peripheral surface, and the tamper-evident bottom portion has a locking means on the inner peripheral surface, A synthetic resin container lid characterized in that a weakened portion is formed on the inner or outer surface of the tamper-evident bottom portion, and the weakened portion is a plurality of arc-shaped or ring-shaped grooves extending circumferentially at circumferential intervals, and the cross-sectional shape of the groove is a triangle having an upper side and a lower side extending radially and inclined downward.

6. 4. The synthetic resin container lid according to claim 3, wherein the upper side extends horizontally and the lower side extends linearly, and the corner connecting the upper side and the lower side is curved.

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