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: A weakened part 32 (a groove) is formed on an outer peripheral surface or an inner peripheral surface of a lower end of a skirt part 22 of a skirt wall 6.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 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 skirt portion below the breakable line, and with a female thread on the inner circumferential surface of the main 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, to thread the male thread of the neck onto the female thread of the lid. The lower portion of the skirt wall's base is then deformed radially inward to form a locking portion that can be locked onto the locking jaw of the neck. To open 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 top wall of the container lid and the main portion of the skirt wall attempt to rise as the lid rotates in the opening direction. However, the locking portion formed at the lower portion of the skirt wall locks into the locking jaw of the neck, preventing the lift. This generates stress in the breakable line, causing the breakable line to break and separating the skirt wall base from the main portion. Thereafter, the bottom of the skirt wall remains on the neck portion, and the top wall and the main portion of the skirt wall are freely raised as the top wall and the main portion of the skirt wall rotate in the opening direction and are separated from the neck portion, thereby opening the neck portion. The fact that the bottom of the skirt wall remains on the neck portion clearly indicates that the required opening operation has been performed on the container lid (tamper-evident function). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 55-9340 Summary of the Invention [Problem to be solved by the invention]

[0005] According to the inventor's experience, conventional synthetic resin container lids of the above-described configuration have a problem to be solved: by engaging a finger or an appropriate tool with the end of the bottom of the skirt wall and rotating the container lid in the opening rotation direction while displacing the end of the bottom of the skirt wall radially outward, the entire container lid can be detached from the mouth and neck portion without breaking the breakable line, and the mouth and neck portion can be opened fraudulently.

[0006] Incidentally, the applicant of the present application disclosed in Patent Application No. 2022-209411, filed prior to the present application, a synthetic resin container lid for a container having a cylindrical mouth and neck portion, the outer surface of which is provided with a male thread and a locking jaw portion located below the male thread, the synthetic resin container lid having 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 breakable line, the skirt wall being divided into a main portion above the breakable line and a hem portion below, the main portion having an internal thread on the inner peripheral surface, the synthetic resin container lid being able to be locked to the mouth and neck portion by deforming multiple points at circumferentially spaced intervals at the bottom of the hem radially inward when attached to the mouth and neck portion (hereinafter referred to as the "prior container lid"). Therefore, in the preceding container lid, the lower part of the bottom of the deformed skirt wall has engaging portions that engage with the neck portion and non-engaging portions that do not engage with the neck portion, which are arranged alternately in the circumferential direction. In the non-engaging portions, a relatively wide gap exists between the inner surface of the skirt wall bottom and the outer surface of the neck portion of the container, so that a finger or an appropriate tool can easily be engaged in the gap.

[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, when the required operation for tampering with the opening and closing of the neck portion is performed as described above, clearly indicates that such operation has been performed. [Means for solving the problem]

[0008] As a result of extensive research, the present inventors have found that the above-mentioned main technical problem can be solved by forming a weakened portion on the outer or inner peripheral surface of the lower end of the bottom of the skirt wall.

[0009] That is, according to the present invention, a synthetic resin container lid that solves the above-mentioned main technical problem is a synthetic resin container lid for a container having a cylindrical neck portion on the outer circumferential surface of which is provided a male thread and a locking jaw portion located below the male thread, The container has a circular top wall and a cylindrical skirt wall that hangs down from the periphery of the top wall, The skirt wall is provided with a circumferentially extending breakable line, and the skirt wall is divided into a main portion above the breakable line and a bottom portion below the breakable line. An internal thread is provided on the inner peripheral surface of the main portion, and the synthetic resin container lid is fitted to the mouth and neck of a container by deforming the lower part of the bottom portion radially inward, A weakened portion is formed at the lower end of the skirt portion of the synthetic resin container lid.

[0010] Preferably, the weakened portion is a circumferentially extending circular ring-shaped groove or a plurality of circumferentially extending arc-shaped grooves spaced apart. In this case, the longitudinal cross-sectional shape of the groove is preferably a triangle having an upper side and a lower side that extends radially downward at an angle. Furthermore, it is preferable that the upper side extends horizontally and the lower side extends linearly, and the corner connecting the upper side and the lower side is curved. The lower part of the hem is deformed at a plurality of circumferentially spaced locations, and the deformed lower part of the hem may have engaging portions that engage with the neck opening and non-engaging portions that do not engage with the neck opening and alternately arranged in the circumferential direction. In this case, it is preferable that the weakened portion is formed in at least the non-engaging portions. [Effects of the Invention]

[0011] In the synthetic resin container lid of the present invention, a weakened portion is formed on the outer or inner surface of the lower end of the bottom of the skirt wall, so that if a finger or an appropriate tool is engaged with the end of the bottom of the skirt wall and an attempt is made to rotate the container lid in the opening rotation direction while displacing the end of the bottom radially outward, the lower end of the bottom of the skirt wall will easily undergo plastic deformation starting from the weakened portion or the weakened portion will easily whiten, making it clear that the mouth and neck have been tampered with. [Brief explanation of the drawings]

[0012] [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. [Figure 3] 2 is a front view, partly in section, showing the container lid shown in FIG. 1 in a state where the lower part of the bottom of the skirt wall is deformed. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0013] 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.

[0014] 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.

[0015] 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 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 skirt portion 22 is connected to the main portion 20 via the plurality of bridging portions 26.

[0016] The outer peripheral surface of the main portion 20 of the skirt wall 6 is formed with anti-slip knurling 28, which consists 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. In a synthetic resin container closure constructed according to the present invention, it is important that a weakened portion is formed on the outer or inner peripheral surface of the lower end of the skirt portion 22. In the illustrated embodiment, the weakened portion is formed by a ring-shaped groove 32 extending in the circumferential direction. As can be seen from FIG. 2 , the longitudinal cross section of the groove 32 is triangular, having an upper side 34 extending substantially horizontally, a corner 36 curved downward radially outward from the radially outer end of the upper side 34, and a lower side 38 extending linearly from the lower end of the corner 36 and inclined radially inward. If desired, the corner 36 may be sharply pointed. The upper edge 34 is preferably shorter than the lower edge 38, i.e., the corner 36 is preferably positioned above the center height position of the vertical width of the opening surface of the groove 32. This is because, when the inner molding die is released in the process of molding the container lid 2, mold removal failure due to catching resistance between the container lid 2 and the inner molding die is suppressed. In addition, the weakened portion, which may be the groove 32, may be formed on the outer peripheral surface of the bottom hem 22.

[0017] 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.

[0018] When fitting the container lid 2 to the mouth and neck portion 100 to seal it after filling the container with contents such as a soft drink, the container lid 2 is fitted onto the mouth and neck portion 100 and rotated in the closing direction, i.e., clockwise as viewed from above in Fig. 1. As a result, the female thread 30 of the container lid 2 is threadedly engaged with the male thread 102 of the mouth and neck portion 100, and the container lid 2 is lowered relative to the male thread 102 as it rotates. When the container lid 2 is lowered to the required position, i.e., the position shown in Fig. 1, the annular ridge 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 outer seal piece 10 formed on the inner surface of the top wall 4 of the container lid 2 come into close contact or abut against the inner and outer circumferential surfaces of the mouth and neck portion 100, respectively, thereby sealing the mouth and neck portion 100. At this time, the upper end of the inner peripheral surface of the skirt portion 22 of the skirt wall 6 faces the outer peripheral surface of the locking jaw 104 of the mouth / neck portion 100, and the lower end of the inner peripheral surface of the skirt portion 22, where the groove 32 is formed, faces the outer peripheral surface of the mouth / neck portion 100 between the locking jaw 104 and the support ring 106. Then, the heated press-deformable member 200 is applied to the outer peripheral surface of the lower part of the skirt portion 22. As a result, as shown in FIG. 3 , the lower part of the skirt portion 22 is deformed radially inward, forming the locking portion 40. The lower end of the inner surface of the locking portion 40 abuts against the outer peripheral surface of the mouth / neck portion 100, and the upper part of the locking portion 40 is locked against the outer peripheral surface or lower surface of the lower end of the locking jaw 104. The groove 32 is located below the locking jaw 104 when viewed in the vertical direction. In the illustrated embodiment, a plurality of locking portions 40 are formed at equal angular intervals in the circumferential direction, and non-locking portions 42 that are not locked to the mouth / neck portion 100 are defined between each of the plurality of locking portions 40. The groove 32 is located in the vertical middle between the locking portions 40 and the non-locking portions 42.

[0019] In the container lid constructed according to the present invention, a weakened portion (groove 32 in the illustrated embodiment) is formed on the outer or inner peripheral surface of the lower end of bottom portion 22 of skirt wall 6. Therefore, when an attempt is made to rotate the container lid in the opening direction by engaging the end of bottom portion 22 with a finger or an appropriate tool and displacing the end of bottom portion 22 radially outward, the lower end of bottom portion 22 of skirt wall 6 easily undergoes plastic deformation starting from the weakened portion or the weakened portion easily whitens, making it clear that the opening and neck portion has been tampered with. If container lid 2 is colored other than white or is transparent, the whitening becomes more noticeable, further improving the clarity of the indication.

[0020] In the illustrated embodiment, there is a relatively wide gap between the inner surface of the bottom 22 of the skirt wall 6 and the outer surface of the mouth and neck portion 100 of the container at the non-locking portions 42 defined between each of the multiple locking portions 40.Therefore, by locking a finger or an appropriate tool into this gap and rotating the container lid 2 in the opening rotation direction while displacing the end of the bottom 22 radially outward, there is a risk that the entire container lid 2 will be detached from the mouth and neck portion 100 without breaking the breakable line 18, thereby causing the mouth and neck portion 100 to be opened fraudulently. However, even in the container lid of the illustrated embodiment, when the end of the bottom portion 22 of the skirt wall 6 is displaced radially outward as described above, the non-locking portion 42 easily undergoes plastic deformation starting from the groove 32 or the groove 32 easily whitens due to the weakened portion formed on the inner or outer surface of the non-locking portion 42, making it clear that the neck portion 100 has been tampered with.

[0021] Furthermore, in the illustrated embodiment, when the end of the hem 22 of the skirt wall 6 is displaced radially outward as described above, due to the triangular cross-sectional shape of the groove 32 formed on the inner or outer peripheral surface of the hem 22, the hem 22 of the skirt wall 6 easily undergoes plastic deformation starting from the corner 36 of the groove 32 or the portion of the hem 22 corresponding to the corner 36 of the groove 32 easily whitens, making it clear that the opening and neck portion 100 has been tampered with.

[0022] 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 Fig. 2. As a result, the male thread 102 and the female thread 30 gradually disengage, and the main portion 20 of the skirt wall 6 moves axially upward as the lid 2 is rotated. Meanwhile, the bottom portion 22 of the skirt wall 6 is prevented from moving axially upward because the locking portion 40 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 bottom portion 22 of the skirt wall 6 is separated from the main portion 20. Thereafter, the bottom 22 of the skirt wall 6 remains on the mouth and neck portion 100, and the top wall 4 of the container lid 2 and the main portion 20 of the skirt wall 6 are rotated and freely moved upward in the axial direction to separate from the mouth and neck portion 100, thus opening the mouth and neck portion 100. The bottom 22 of the skirt wall 6 remaining on the mouth and neck portion 100 clearly indicates that the mouth and neck portion 100 has been opened.

[0023] Here, by setting the breaking strength of the portion of the bottom 22 of the skirt wall 6 where the groove 32 is formed to be equal to or lower than the breaking strength of the bridging portion 26, the lower end of the bottom 22 of the skirt wall 6 is more easily plastically deformed from the weakened groove 32 as a base point, or the weakened portion is more easily whitened, making it more obvious that the mouth and neck portion has been tampered with. Furthermore, when the locking portion 40 is locked with the locking jaw 104, stress is applied to the locking portion 40, and this stress is also transmitted to the weakened groove 32, so that the whitening of the portion where the weakened groove 32 is formed also makes it clear that the mouth and neck portion 100 has been opened.

[0024] Although the synthetic resin container closure constructed according to the present invention has been described in detail above with reference to the accompanying drawings, the present invention is not limited to the above-described embodiment, and appropriate modifications and variations are possible without departing from the spirit and scope of the present invention. For example, in the illustrated embodiment, the groove 32 constituting the weakened portion is annular and extends circumferentially. Therefore, the groove 32 is formed continuously along the entire inner surface of the bottom 22 of the skirt wall 6, i.e., along the inner surfaces of the locking portion 40 and the non-locking portion 42. However, considering the gap between the inner surface of the bottom 22 of the skirt wall 6 and the outer surface of the container neck 100, the groove 32 need only be formed on the inner surface of the non-locking portion 42, and not necessarily on the inner surface of the locking portion 40. Therefore, instead of the annular groove 32 extending circumferentially, the weakened portion may be a plurality of arc-shaped grooves extending at intervals in the circumferential direction. Furthermore, the weakened portion does not necessarily have to be a groove, and may be thin-walled, for example. Furthermore, when the weakened portion is a groove and the cross-sectional shape of the groove is triangular, the engagement portion 40 may be formed around the entire circumference, and further, the groove may be formed at any vertical position on the bottom portion 22 of the skirt wall 6. [Explanation of symbols]

[0025] 2: Container lid 4: Top wall 6: Skirt wall 18: Breakable line 20: Main section 22: Hem 30:Female thread 32: Weakened part (groove) 40: Locking part 42: Non-locking part

Claims

1. A synthetic resin container lid for a container having a cylindrical neck portion, the outer circumferential surface of which is provided with a male thread and a locking jaw portion located below the male thread, The container has a circular top wall and a cylindrical skirt wall that hangs down from the periphery of the top wall, The skirt wall is provided with a circumferentially extending breakable line, and the skirt wall is divided into a main portion above the breakable line and a bottom portion below the breakable line. An internal thread is provided on the inner peripheral surface of the main portion, and the synthetic resin container lid is fitted to the neck of a container by deforming the lower portion of the bottom portion radially inward, A synthetic resin container lid characterized in that a weakened portion is formed at the lower end of the skirt portion.

2. 2. The synthetic resin container closure according to claim 1, wherein said weakened portion is a circular groove extending in the circumferential direction or a plurality of arc-shaped grooves extending in the circumferential direction at intervals in the circumferential direction.

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 lower portion of the skirt is deformed at a plurality of circumferentially spaced locations, 2. A synthetic resin container lid as described in claim 1, wherein the lower part of the deformed hem has engaging portions that engage with the mouth and neck portion and non-engaging portions that do not engage with the mouth and neck portion arranged alternately in the circumferential direction.

6. 6. The synthetic resin container lid according to claim 5, wherein the weakened portion is formed at least in the non-locking portion.

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