JP7574024B2 - Synthetic Resin Cap - Google Patents

Description

The present invention relates to a synthetic resin cap that is attached to the mouth of a container that contains contents such as a beverage.

Caps that are attached to the mouth of a container that contains a beverage or other content and that are configured to enable a user to check at a glance whether the container has been opened or not are widely known. For example, the cap disclosed in Patent Document 1 has a skirt wall 52 with a female thread 51 that screws into a male thread M1 formed on the outer periphery of the container mouth M, as shown in Figures 5 (A) and (B), and a tamper-evident band (tamper-evident hem) 54 connected to the lower part of the skirt wall 52 via an annular weakened portion (break line) 53.

When the above cap is opened (initial uncapping operation) while attached to the container mouth M, the hook (locking means) 55 on the inner circumference of the tamper evidence band 54 locks with the annular protrusion (locking jaw) M2 on the outer circumference of the container mouth M, and then the annular weakened portion 53 separating the tamper evidence band 54 from the skirt wall 52 breaks, and the skirt wall 52 and the tamper evidence band 54 are separated from each other. Therefore, by visually checking whether the annular weakened portion 53 has been broken, it is easy to confirm whether the opening operation has been performed.

Patent No. 5554574

However, with the cap shown in FIG. 5, there is a risk that the tamper evidence band 54 may crack when capping the container mouth M, and this cracking is more likely to occur, for example, when the tamper evidence band 54 is made thinner.

The present invention was made with the above in mind, and its purpose is to provide a synthetic resin cap that can prevent the tamper evidence band from cracking.

In order to achieve the above object, the synthetic resin cap of the present invention is a cap comprising a skirt wall provided with a female thread that screws into a male thread formed on the outer periphery of a container mouth, and a tamper evidence band connected to the lower part of the skirt wall via an annular weakened part, wherein on the inner periphery of the tamper evidence band, hooks that can be engaged from below with an annular protrusion formed on the outer periphery of the container mouth and non-engaging parts that do not engage with the annular protrusion are arranged alternately in the circumferential direction, and the upper part of the non-engaging part protrudes farther inwardly from the tamper evidence band than the lower part, and the tamper evidence band in a boundary region located at the boundary between the upper part and the lower part is formed with a tamper evidence band having a width that is longer than the width of the tamper evidence band. The amount of inward protrusion of the tamper evidence band is configured to gradually decrease toward the bottom, the lower end of the boundary region is located below the portion of the hook that protrudes most inwardly into the tamper evidence band, the thickness of the upper portion of the non-locking portion is constant from top to bottom, and no portion protrudes inwardly on the inner surface of the upper portion, and in the region in the circumferential direction of the tamper evidence band where the non-locking portion is located, the thickness does not change from the lower end of the upper portion of the non-locking portion to the upper end of the tamper evidence band , and the upper end of the boundary region is located above the engagement portion of the hook (Claim 1).

In the synthetic resin cap, a fitting portion into which the annular protrusion fits is provided above the hook on the inner periphery of the tamper evidence band, and the left and right ends of the fitting portion are configured so that the amount of inward protrusion of the tamper evidence band gradually decreases toward the left and right ends, and the left and right ends of the upper part of the non-locking portion are configured so that the amount of inward protrusion of the tamper evidence band gradually increases toward the left and right ends, and the cross-sectional shape of the inner surface of the connecting portion between the left and right ends of the fitting portion and the left and right ends of the upper part of the non-locking portion may be curved (Claim 2).

The present invention provides a synthetic resin cap that can prevent the tamper evidence band from cracking.

In other words, in the synthetic resin cap of the invention according to each claim of this application, the lower end of the boundary region of the non-locking portion is positioned lower than the portion of the hook that protrudes most inwardly into the tamper evidence band. Therefore, when the guide portion comes into contact with the annular protrusion of the container mouth during capping and the tamper evidence band expands in diameter, stress is less likely to concentrate in the lower portion, which is thinner than the upper portion of the non-locking portion, making it less likely for cracks to occur in the tamper evidence band.

In the synthetic resin cap of the invention according to claim 2, for example, when the tamper evidence band expands during capping, stress is less likely to concentrate on the connecting portion, so cracks in the tamper evidence band can be prevented.

1A is a vertical cross-sectional view showing a configuration of a synthetic resin cap according to one embodiment of the present invention, and FIG. 1B is a development view of the inner peripheral surface of the synthetic resin cap. 1A is a front half of a cross-sectional view (horizontal cross-sectional view) taken along line F2A-F2A in FIG. 1B, and FIG. 1B is a horizontal cross-sectional view showing a schematic configuration of the upper portion of the non-locking portion and the engaging portion located at part X in FIG. 1A is an image showing the vertical cross-sectional configuration of the synthetic resin cap, and FIG. 1B is an image showing the vertical cross-sectional configuration of the non-locking portion of the synthetic resin cap. FIG. 2 is a vertical cross-sectional view showing a configuration of a main part of the synthetic resin cap. 1A is a front view of a conventional synthetic resin cap, and FIG. 1B is a partial cross-sectional view of the cap attached to the mouth of a container.

The following describes an embodiment of the present invention.

The synthetic resin cap (hereinafter referred to as the cap) 1 shown in Fig. 1(A) and Fig. 3(A) is used by being attached to a container mouth M (e.g., the mouth of a container such as a PET bottle) having a male thread M1 and an annular protrusion M2 as shown in Fig. 5(B), and is integrally molded from polyethylene by compression molding or injection molding. The material from which the cap 1 is made is not particularly limited, and in addition to the polyethylene used in this embodiment, polypropylene, etc. are preferably used.

The cap 1 has a top wall 2 that is generally circular in plan view, and a skirt wall 3 that is generally cylindrical and extends downward from the outer periphery of the top wall 2. Here, the skirt wall 3 has a knurled groove 4 on its outer periphery and a female thread 5 on its inner periphery, and this female thread 5 can be connected to a male thread M1 formed on the outer periphery of the container mouth M.

When the cap 1 is rotated and attached to the container mouth M so that the male thread M1 of the container mouth M is joined to the female thread 5 of the skirt wall 3, the annular middle leg (inner ring) 6, the annular rib 7, and the annular outer leg (outer ring) 8 connected to the inner surface (lower surface) of the top wall 2 come into close contact with the container mouth M, thereby sealing the container mouth M. In other words, when the cap 1 is attached to the container mouth M, the middle leg 6 is inserted into the container mouth M and comes into close contact with the inner peripheral surface of the container mouth M, the annular rib 7 comes into close contact with the annular upper end surface of the container mouth M, and the outer leg 8 comes into close contact with the outer peripheral surface of the container mouth M.

The cap 1 is also a pilfer-proof cap that has the function of proving that the cap is unopened (has never been opened). When an unopened cap 1 attached to the container mouth M is opened (the first time the cap is opened), the cap 1 is rotated so that the connection between the male thread M1 and the female thread 5 is released, and the cap 1 is detached from the container mouth M, but the tamper-evidence band (hereinafter simply referred to as the "band") 9 connected to the lower part of the skirt wall 3 remains on the container mouth M.

That is, the band 9 is connected to the lower part of the skirt wall 3 via an annular weakened portion 10 (see FIG. 1(A)) that extends around the entire circumference of the skirt wall 3. The annular weakened portion 10 is composed of (perforated) slits that extend intermittently in the circumferential direction of the skirt wall 3 and band 9 to separate the skirt wall 3 and band 9 from each other vertically, and bridges that exist between adjacent slits, and the bridges break when pulled with a specified force.

Here, the outer diameter of the band 9 is uniform from top to bottom, while on the inner periphery of the band 9, hooks 11 that protrude inward from the band and can be engaged from below with the annular protrusion M2 (see FIG. 5(B)) provided on the outer periphery of the container mouth M, and non-engaging parts 12 that do not engage with the annular protrusion M2 are arranged alternately in the circumferential direction. In this example, five hooks 11 and five non-engaging parts 12 are provided (see FIG. 1(B)). When the cap 1 is attached to the container mouth M, each hook 11 is located approximately below the annular protrusion M2 (see FIG. 5(B)) formed on the outer periphery of the container mouth M below the male thread M1, and engages with the annular protrusion M2 when the cap is opened.

As shown in Figures 1(A), 3(A) and 4, on the inner periphery of the band 9, above the hook 11, there is provided a fitting portion 13 that protrudes inwardly into the band 9 and has a maximum protrusion amount smaller than the maximum protrusion amount of the hook 11. Furthermore, above the fitting portion 13, there is a series of inclined portions 14 that protrude inwardly into the band 9 less the further upward.

When the cap 1 is attached to the container mouth M and unopened, the annular projection M2 is located inside or above the inclined portion 14. When the cap 1 is rotated in the opening direction from this state, the cap 1 rises relative to the container mouth M, the fitting portion 13 fits into the annular projection M2, and the cap 1 is centered so that the central axis of the cap 1 coincides with the central axis of the container mouth M, while the hook 11 engages with the annular projection M2 from below. If the cap 1 continues to be rotated further in the opening direction, the annular weakened portion 10 eventually breaks, and the band 9 remains in the container mouth M, while the cap body consisting of the top wall 2 and skirt wall 3 above it detaches from the container mouth M.

Therefore, before the hook 11 engages with the annular protrusion M2 from below, the inclined portion 14 abuts against the annular protrusion M2, and the fitting portion 13 fits into the outer circumferential surface of the annular protrusion M2 and is centered, preventing the band 9 from lifting at an angle and allowing the annular weakened portion 10 to break approximately uniformly without being biased, resulting in good tamper evidence. When opening the container, the fitting portion 13 fits into the outer circumferential surface of the annular protrusion M2 of the container mouth M, and the hook 11 reliably engages with the annular protrusion M2, preventing the hook 11 from climbing over the annular protrusion M2 without breaking the annular weakened portion 10, preventing the occurrence of what is known as slipping out.

As shown in FIG. 4, the non-locking portion 12 is configured so that its upper portion 12a protrudes further inwardly into the band 9 than its lower portion 12b, and the amount of protrusion of the boundary region 12c located at the boundary between the upper portion 12a and the lower portion 12b into the band 9 gradually decreases downward, and the lower end of the boundary region 12c is located below the maximum protruding portion P, which is the portion of the hook 11 that protrudes most inwardly into the band 9. This configuration makes it less likely for the band 9 to crack, for example, when capping.

That is, as shown in FIG. 4, from its bottom to top, the hook 11 has, in that order, a guide portion 11a that contacts the annular protrusion M2 when capping, a curved portion 11b that includes the maximum protruding portion P, and an engagement portion 11c that engages with the annular protrusion M2 when opening the cap. Here, the guide portion 11a has a greater gradient (angle of inclination from the horizontal direction) than the engagement portion 11c, and the two portions 11a and 11c have opposite gradients. In addition, the curved portion 11b is curved so as to smoothly connect the guide portion 11a and the engagement portion 11c.

In the cap 1 provided with the hook 11 in this manner, the guide portion 11a comes into contact with the annular projection M2 of the container mouth M during capping, causing the band 9 to expand in diameter. If the lower end of the boundary region 12c of the non-locking portion 12 is located above the maximum protruding portion P during this expansion, the stress caused by the expansion deformation will be concentrated on the lower portion 12b, which is thinner than the upper portion 12a, making the lower portion 12b more likely to crack. However, in this example, the lower end of the boundary region 12c of the non-locking portion 12 is located below the maximum protruding portion P and even below the curved portion 11b which includes this maximum protruding portion P, making it difficult for the above-mentioned stress concentration to occur, and therefore difficult for the band 9 to crack.

As shown in FIG. 1(A), the band 9 in this example has a thickness above the boundary region 12c of each non-locking portion 12 that is greater than the thickness below it.

2(B), the left and right ends of the fitting portion 13 are configured so that the amount of inward protrusion of the band 9 gradually decreases toward the left and right ends, and the left and right ends of the upper portion 12a of the non-locking portion 12 are configured so that the amount of inward protrusion of the band 9 gradually increases toward the left and right ends, and the cross-sectional shape of the inner surface of the connecting portion 15 between the left and right ends of the fitting portion 13 and the left and right ends of the upper portion 12a of the non-locking portion 12 is curved (R-shaped). With this configuration, stress is less likely to concentrate on the connecting portion 15 when the band 9 expands in diameter during capping, for example, so that cracks in the band 9 can be prevented. To achieve this effect, it is preferable that the cross-sectional shape of the inner surface of the connecting portion 15 is curved (R-shaped) with a radius of curvature of at least 1/100 of the outer diameter of the cap 1 (in this example, the outer diameter of the cap 1 is 57 mm and the radius of curvature is 1.02 mm).

By setting the central angle θ (see FIG. 2A) in the cross section of the non-locking portion 12 to 5° to 7° (preferably about 6°), a sufficient distance can be ensured between adjacent hooks 11, and the resistance (closure resistance) during capping of the cap 1 can be reduced.

In addition, in this example, the thickness of the upper portion 12a of the non-locking portion 12 is constant from top to bottom, and there is no portion on the inner peripheral surface of the upper portion 12a that protrudes inward (see Figures 3(B) and 4). This makes it easier for the upper portion 12a of the non-locking portion 12 to expand and deform uniformly overall during capping than when such a portion is provided, which also reduces the resistance (closure resistance) when capping the cap 1.

As shown in FIG. 1(B), the female thread 5 of the cap 1 in this example is an interrupted thread in which threads 16 and unthreaded portions 17 are arranged alternately, and each unthreaded portion 17 is configured so that the non-locking portion 12 provided between circumferentially adjacent hooks 11 is not located at the end of the extension in the axial direction of the skirt wall 3 (downward in FIG. 1(B)). In other words, the positions of each unthreaded portion 17 and each non-locking portion 12 are shifted in the circumferential direction. This configuration makes it possible to prevent the occurrence of welds that can lead to vertical cracks in the band 9.

Moreover, the female thread 5 in this example extends in a spiral shape around the skirt wall 3 twice, and each unthreaded portion 17 has other unthreaded portions 17 in the axial direction (up and down direction), and the circumferential width and end shape of the thread 16 are different for each turn. That is, as shown in FIG. 1(B), each of the threads 16 in the lower turn is wider in the circumferential direction than each of the threads 16 in the upper turn, and the left and right ends of each of the threads 16 in the lower turn (except for the lowest thread 16) are wider in the circumferential direction than both left and right ends of each of the threads 16 in the upper turn (parts that protrude radially inward less than the left and right central parts). In this way, by providing the above-mentioned area difference between the threads 16 in the lower turn and the threads 16 in the upper turn that come out before the threads 16 in the lower turn when releasing the cap during molding, a release resistance reduction effect is obtained.

The present invention is not limited to the above embodiment, and can be modified in various ways without departing from the spirit of the present invention. For example, the following modifications can be mentioned:

In the example of FIG. 4, the lower end of the boundary region 12c of the non-locking portion 12 is at a height position equivalent to the guide portion 11a of the hook 11, but this is not limited thereto, and the lower end of the boundary region 12c may be located lower than the guide portion 11a.

In the example of FIG. 4, the upper end of the boundary region 12c of the engaged portion 12 is located above the engaging portion 11c of the hook 11 (at a height position corresponding to the guide portion 18 between the fitting portion 13 and the engaging portion 11c), but this is not limited thereto, and the upper end of the boundary region 12c may be at a height position corresponding to the engaging portion 11c, at a lower position, or at a position above the guide portion 18.

It goes without saying that the above modifications may be combined as appropriate.

REFERENCE SIGNS LIST 1 Synthetic resin cap 2 Top wall 3 Skirt wall 4 Knurled groove 5 Female thread 6 Middle leg 7 Annular rib 8 Outer leg 9 Tamper evidence band 10 Annular weakened portion 11 Hook 11a Guide portion 11b Curved portion 11c Engagement portion 12 Non-engaging portion 12a Upper portion 12b Lower portion 12c Boundary region 13 Fitting portion 14 Inclined portion 15 Connecting portion 16 Thread 17 Unthreaded portion 18 Guide portion 51 Female thread 52 Skirt wall 53 Annular weakened portion 54 Tamper evidence band 55 Hook M Container mouth portion M1 Male thread M2 Annular protrusion P Maximum protruding portion

Claims (2)

A cap comprising a skirt wall having an internal thread that is screwed into an external thread formed on the outer periphery of a container mouth, and a tamper-evident band connected to a lower portion of the skirt wall via an annular weakened portion,
On the inner peripheral side of the tamper evidence band, hooks that can be engaged from below with an annular protrusion provided on the outer peripheral side of the container mouth portion and non-engaging portions that do not engage with the annular protrusion are alternately arranged in the circumferential direction,
The non-locking portion is configured such that its upper portion protrudes more inwardly into the tamper evidence band than its lower portion, and the amount of protrusion of a boundary region located at the boundary between the upper portion and the lower portion into the tamper evidence band gradually decreases toward the lower portion,
The lower end of the boundary region is located below the portion of the hook that protrudes most inwardly from the tamper evidence band,
A synthetic resin cap characterized in that the thickness of the upper part of the non-locking portion is constant from top to bottom, there is no portion protruding inward on the inner surface of the upper part, and in the area in the circumferential direction of the tamper evidence band where the non-locking portion is provided, the thickness does not change from the lower end of the upper part of the non-locking portion to the upper end of the tamper evidence band, and the upper end of the boundary area is located above the engagement portion of the hook . A fitting portion into which the annular protrusion fits is provided on the inner peripheral side of the tamper evidence band and above the hook,
The left and right ends of the fitting portion are configured so that the amount of inward protrusion of the tamper evidence band gradually decreases toward the left and right ends,
The left and right ends of the upper portion of the non-locking portion are configured so that the amount of inward protrusion of the tamper evidence band gradually increases toward the left and right ends,
2. The synthetic resin cap according to claim 1, wherein the inner surface of the connecting portion between the left and right ends of the fitting portion and the left and right ends of the upper portion of the non-locking portion has a curved cross section.

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