Synthetic resin cap

Abstract

To provide a technique for improving a tamper evidence property while securing rigidity of a tamper evident part in a synthetic resin cap.SOLUTION: A synthetic resin cap 1 according to the present invention includes a cap body 10 including a top surface portion 11 and a skirt portion 12 extending from a peripheral edge of the top surface portion 11, and a tamper-evident portion 30 connected to the skirt portion 12 via a breakable weakened line 20, wherein the tamper-evident portion 30 includes a locking portion 40 formed on an inner wall surface 31 of the tamper-evident portion 30 and lockable to a container mouth portion 2, and a thin portion 50 formed on the inner wall surface 31 and / or an outer wall surface 32 of the tamper-evident portion 30 and below the locking portion 40.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] BACKGROUND ART Conventionally, caps made of synthetic resins and having tamper-evident properties that clearly indicate to consumers that a container has been opened have been known.

[0003] For example, Patent Document 1 describes a synthetic resin container lid that has a circular top wall and a cylindrical skirt wall hanging down from the periphery of the top wall, with a circumferentially extending fracture line formed on the skirt wall, and the skirt wall divided into a main portion above the fracture line and a tamper-evident bottom portion below the fracture line, with a female thread formed on the inner surface of the main portion and a locking means disposed on the inner surface of the tamper-evident bottom portion, and above the locking means on the inner surface of the tamper-evident bottom portion are a loose-fitting upper portion with an inner diameter d1 and a fitting lower portion with an inner diameter d2, with the inner diameter d2 being smaller than the inner diameter d1.

[0004] Patent document 2 also describes a synthetic resin container lid which comprises a circular top wall and a cylindrical skirt wall hanging down from the periphery of the top wall, with a circumferential breakable line formed on the skirt wall extending circumferentially, the skirt wall being divided into a main portion above the circumferential breakable line and a tamper-evident hem portion below the circumferential breakable line, with a female thread formed on the inner surface of the main portion and a locking means disposed on the inner surface of the tamper-evident hem portion, and which is characterized in that the inner surface of the tamper-evident hem portion is provided with an inverted truncated cone-shaped mating surface which extends radially outward and upward from the base edge of the upper surface of the locking means. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-143942 [Patent Document 2] Japanese Patent Application Laid-Open No. 2013-126881 Summary of the Invention [Problem to be solved by the invention]

[0006] In the prior art such as those described in Patent Documents 1 and 2, the tamper-evident part is locked to the container opening via a locking part, and is therefore prevented from rising relative to the container opening. Therefore, once the container is opened by a consumer, the weakened line separating the cap body and the tamper-evident part breaks, allowing the cap body above the weakened line to be detached from the container opening, while the tamper-evident part below the weakened line remains at the container opening.

[0007] However, there is a possibility that a malicious person other than a consumer could insert a finger or tool into the lower end of the tamper-evident portion and remove the cap together with the tamper-evident portion from the container mouth without breaking the weakened line. In this case, if the tamper-evident portion is only slightly deformed and the malicious person reattaches the cap to the container mouth, consumers may not realize that the container has been tamper-evident, so improvements in tamper-evident properties are required. On the other hand, since synthetic resin caps are stored in tanks or other containers with other caps between the time they are molded and when they are attached to the container mouth, they are then packed in boxes or other containers for transportation, so they must also be rigid enough to prevent deformation due to the load from other caps.

[0008] To improve tamper-evident properties, it is conceivable to deform the tamper-evident portion more significantly than conventional methods when the container is tamper-opened, making it easier for consumers to visually recognize this. However, significant deformation of the tamper-evident portion reduces the rigidity of the tamper-evident portion, which may cause the tamper-evident portion to deform under the load described above. This may lead to problems when attaching the cap to the opening of the container.

[0009] In view of the above circumstances, an object of the present invention is to provide a technology for improving the tamper-evident properties of a synthetic resin cap while ensuring the rigidity of the tamper-evident portion. [Means for solving the problem]

[0010] In order to solve the above problems, one form of the synthetic resin cap of the present invention is a synthetic resin cap comprising: (1) a cap body including a top surface portion and a skirt portion extending from the periphery of the top surface portion, and a tamper-evident portion connected to the skirt portion via a breakable weakened line, wherein the tamper-evident portion includes a locking portion formed on the inner wall surface of the tamper-evident portion and capable of locking with the container mouth portion, and a thin-walled portion formed on the inner wall surface and / or outer wall surface of the tamper-evident portion and below the locking portion.

[0011] In the synthetic resin cap described in (1) above, (2) it is preferable that the locking portions are formed intermittently at predetermined intervals, and that the thin-walled portions are formed only on the inner wall surface and / or outer wall surface corresponding to the hanging down of the locking portions.

[0012] In the synthetic resin cap described in (2) above, (3) it is preferable that the engaging portion has a central region including an area where the amount of radial inward protrusion of the tamper-evident portion is greatest, and peripheral regions extending from the central region along the circumferential direction of the tamper-evident portion and in which the amount of protrusion decreases with increasing distance from the central region.

[0013] In the synthetic resin cap described in (3) above, (4) it is preferable that the thin-walled portion is formed only on the inner wall surface and / or the outer wall surface corresponding to the hanging portion of the central region.

[0014] In the synthetic resin cap described in (1) above, (5) it is preferable that the thin-walled portion is formed on the inner wall surface.

[0015] In the synthetic resin cap described in (1) above, (6) the thin portion is preferably a groove extending along the central axis of the tamper-evident portion.

[0016] In the synthetic resin cap described in (6) above, (7) it is preferable that the angle formed between the extending direction of the groove and the central axis is equal to or greater than 0 degrees and less than 30 degrees.

[0017] In the synthetic resin cap described in (6) or (7) above, (8) it is preferable that the groove reaches the lower end of the tamper-evident portion.

[0018] In the synthetic resin cap described in (1) above, (9) in a cross-sectional view passing through the central axis of the tamper-evident portion, it is preferable that the engaging portion includes an upper surface along the top surface portion and a lower surface that slopes radially from the upper surface toward the lower end of the tamper-evident portion, and that the inner wall surface of the skirt portion is formed with a female thread that screws into the screw of the container mouth portion. [Effects of the Invention]

[0019] According to the present invention, in a synthetic resin cap, it is possible to improve the tamper-evident property while ensuring the rigidity of the tamper-evident portion. [Brief explanation of the drawings]

[0020] [Figure 1]1 is a front view of a synthetic resin cap according to one embodiment of the present invention, along with a half cross-sectional view cut along a plane passing through the center axis of a tamper-evident portion and a container opening (indicated by a two-dot chain line). [Figure 2] 2 shows a view of the synthetic resin cap shown in FIG. 1 as seen from below. [Figure 3] 3 is a partially enlarged view of the area indicated by the dashed line in FIG. 2. [Figure 4] The structure of the AA cross section in FIG. 3 is shown. [Figure 5] 1A and 1B are diagrams illustrating the tamper-evident properties of a synthetic resin cap according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0021] Hereinafter, preferred embodiments of the present invention will be described. Hereinafter, the terms "upper" and "lower" refer to the upper and lower sides, respectively, in the state shown in Fig. 1 (i.e., the state in which the synthetic resin cap 1 is upright), unless otherwise specified. Furthermore, while the X, Y, and Z directions are appropriately defined in the explanations using the drawings, these are definitions provided for the sake of convenience and do not unduly limit the present invention.

[0022] <1. Synthetic resin cap> 1, a synthetic resin cap 1 (hereinafter sometimes abbreviated as "cap 1") includes a cap body 10 and a tamper-evident portion 30 below a breakable weakened line 20. Examples of synthetic resin include polyethylene and polypropylene, but the present invention is not limited to these.

[0023] (Cap body) The cap body 10 includes a top surface 11 and a skirt portion 12 extending from the periphery of the top surface 11. In this embodiment, the cap body 10 has, for example, a cylindrical shape. The top surface 11 has, for example, a circular shape when the cap 1 is viewed from above. An inner seal portion 13 and an outer seal portion 14 are formed on the back surface of the top surface 11, hanging downward. Both the inner seal portion 13 and the outer seal portion 14 have a cylindrical shape, and the inner seal portion 13 extends further downward than the outer seal portion 14. In addition, an annular ridge 15, which is smaller than the inner seal portion 13 and the outer seal portion 14, is formed between the inner seal portion 13 and the outer seal portion 14.

[0024] The skirt portion 12 preferably hangs downward from the periphery of the top surface 11. Furthermore, an internal thread 17 that threadably engages with the screw 3 of the container opening 2 is preferably formed on the inner wall surface 16 of the skirt portion 12. In the example shown in FIG. 1, a plurality of internal threads 17 are formed at predetermined intervals that can be designed appropriately along the circumferential direction of the cap 1. However, the internal threads 17 are not necessarily required as long as the cap 1 can be attached to the container opening 2. Furthermore, an external wall surface 18 of the skirt portion 12 preferably has an anti-slip portion 19 formed by knurling or the like, in which convex portions and concave portions are alternately arranged along the circumferential direction of the cap 1.

[0025] (Tamper Evident Department) The tamper-evident portion 30 is connected to the skirt portion 12 via the aforementioned breakable weakened line 20. When opening the container, a consumer rotates the cap body 10 of the cap 1 attached to the container mouth 2 in the opening direction. The opening direction is, for example, counterclockwise when viewing the container mouth 2 from above. This breaks the weakened line 20, and the cap body 10 is separated from the tamper-evident portion 30. As the screw 3 and the female thread 17 are released from their respective threaded engagement, the cap body 10 rotates and rises, allowing it to be removed from the container mouth 2. Meanwhile, because the tamper-evident portion 30 is engaged with the container mouth 2 by the engaging portion 40 (described later), even if the weakened line 20 breaks, it is prevented from rising and remains in the container mouth 2. This ensures tamper-evident properties, clearly indicating to consumers that the container has been opened. It is preferable that the weakened lines 20 are a plurality of slits formed intermittently at predetermined intervals along the circumferential direction of the cap 1, which can be designed appropriately, but the present invention is not limited to this, and the weakened lines 20 may be formed continuously along the circumferential direction of the cap 1.

[0026] (Latching part) The tamper-evident portion 30 includes a locking portion 40 formed on the inner wall surface 31 of the tamper-evident portion 30 and capable of being locked to the container opening 2. Referring to FIG. 2 , the locking portion 40 may be formed discontinuously at predetermined intervals that can be designed appropriately. Alternatively, a plurality of locking portions 40 (e.g., five locking portions 40) may be formed at predetermined intervals along the circumferential direction of the tamper-evident portion 30, and each locking portion 40 may be a locking protrusion that protrudes radially inward from the tamper-evident portion 30. However, the present invention is not limited to this. The locking portion 40 may be formed continuously along the circumferential direction of the tamper-evident portion 30, and may be, for example, a ring-shaped locking protrusion. The height position of the locking portion 40 is designed appropriately so that an upper surface 43 of the locking portion 40 (described later) can be locked to the lower surface of the locked portion 4 of the container opening 2.

[0027] 3, the locking portion 40 preferably has a central region 41 and a peripheral region 42. Here, the central region 41 is a region that includes an area where the amount of protrusion of the tamper-evident portion 30 toward the inside in the radial direction is greatest. The peripheral region 42 is a region that extends from the central region 41 along the circumferential direction of the tamper-evident portion 30 and where the amount of protrusion decreases with increasing distance from the central region 41. In the example shown in FIG. 3, two peripheral regions 42 are present on both circumferential ends of the central region 41 of each locking portion 40.

[0028] As described above with reference to FIG. 1 , tamper-evident portion 30 is locked to container opening 2 by locking portion 40, and therefore is prevented from rising even if weakened line 20 is broken by the consumer, and remains at container opening 2. Specifically, with reference to FIGS. 1 and 3 as well, central region 41 of locking portion 40 is a region that abuts against locked portion (so-called turnip) 4 of container opening 2 after cap 1 is attached to container opening 2. Note that central region 41 may be a region having a length that is, for example, approximately 60% to 80% of the length of locking portion 40 extending in the circumferential direction of tamper-evident portion 30. In this way, tamper-evident portion 30 is prevented from rising even if weakened line 20 is broken by the consumer, and remains at container opening 2, because central region 41 of locking portion 40 abuts against locked portion 4. From this perspective, central region 41 has a protrusion amount necessary to prevent locking portion 40 from climbing over locked portion 4 and lifting tamper-evident portion 30. However, the protrusion amount of central region 41 may be constant along the circumferential direction of tamper-evident portion 30, or may protrude further near the center of central region 41, as long as it can prevent locking portion 40 from climbing over locked portion 4. Note that "near the center" refers to a region that includes a center line located equidistant from both circumferential ends of central region 41 and a predetermined range from the center line (for example, a range up to about 10% of the extension length of central region 41 along the circumferential direction of tamper-evident portion 30), but the present invention is not limited to this.

[0029] 1 and 4, in a cross-sectional view passing through the central axis C1 of the tamper-evident portion 30, the locking portion 40 preferably includes an upper surface 43 along the top surface 11 of the cap body 10, and a lower surface 44 that slopes radially from the upper surface 43 toward the lower end 33 of the tamper-evident portion 30. The upper surface 43 may also slope radially inward of the tamper-evident portion 30 and toward the lower end 33. The locking portion 40 may also include a corner 45 between the upper surface 43 and the lower surface 44 that continues from the upper surface 43 and curves toward the lower end 33.

[0030] (thin walled section) Referring to FIG. 1 , the thin-walled portion 50 in this embodiment is formed on the inner wall surface 31 of the tamper-evident portion 30 and below the locking portion 40. Here, as described above, there is a risk that a malicious person could insert a finger or a tool into the lower end 33 of the tamper-evident portion 30, thereby tampering (breaking open) the container. That is, there is a risk of tampering, such as by rotating the cap 1 in the opening direction while deforming the lower end 33 of the tamper-evident portion 30 from the radially inner side to the outer side, thereby removing the cap 1 from the container opening 2 without breaking the weakened line 20. However, according to this embodiment, even if the container is tampered with, a portion of the outer wall surface 32 of the tamper-evident portion 30 corresponding to the back side of the thin-walled portion 50 is deformed, destroyed, or whitened, starting from the thin-walled portion 50. This makes it easier for consumers and others to visually recognize tampering by a malicious person, improving tamper-evident properties. 5, outer wall surface 32 of tamper-evident portion 30 is whitened and leaves scars 51 that look like they have been torn, making scars 51 easier for consumers to see, improving tamper evidence. Furthermore, the area where thin-walled portion 50 is formed is limited to the area below locking portion 40 of tamper-evident portion 30, where a relatively high level of strength is ensured. Therefore, even when thin-walled portion 50 is formed, the rigidity of tamper-evident portion 30 can be ensured.

[0031] Referring to FIG. 3 , when the locking portions 40 are formed intermittently at predetermined intervals, the thin-walled portions 50 are preferably formed only on the inner wall surface 31 of the tamper-evident portion 30 corresponding to the hanging portions of the locking portions 40, from the viewpoint of improving tamper evidence while ensuring the rigidity of the tamper-evident portion 30. In other words, it is preferable that the thin-walled portions 50 are not formed on the inner wall surface corresponding to the hanging portions between the locking portions 40. From the same viewpoint, when the locking portion 40 has a central region 41 and a peripheral region 42, it is preferable that the thin-walled portions 50 are formed only on the inner wall surface corresponding to the hanging portions of the central region 41. Furthermore, it is more preferable that the thin-walled portions 50 are formed only on the inner wall surface corresponding to the hanging portions near the center of the central region 41. Note that in this embodiment, one thin-walled portion 50 is formed per locking portion 40, but the present invention is not limited thereto, and multiple thin-walled portions 50 may be formed per locking portion 40. In this case, it is preferable that any thin-walled portion 50 is formed only on the inner wall surface corresponding to the hanging portion of the central region 41 .

[0032] When a container is tampered with, an external force having at least a component along the central axis C1 of the tamper-evident portion 30 is often applied from the lower end 33 of the tamper-evident portion 30. Therefore, the thin-walled portion 50 is preferably a groove extending along the central axis C1 of the tamper-evident portion 30. This configuration results in more pronounced deformation, destruction, or whitening of a portion of the outer wall surface 32 of the tamper-evident portion 30 corresponding to the back surface of the thin-walled portion 50. With particular reference to FIG. 3 , the angle formed between the extension direction C2 of the groove corresponding to the thin-walled portion 50 and the central axis C1 of the tamper-evident portion 30 is preferably between 0 degrees and 30 degrees. This is because the external force also has a component directed from the radially inner side to the radially outer side of the tamper-evident portion 30. Having this angle within the above range makes the tamper-evident portion 30 more likely to tear, making it easier for consumers and others to visually recognize that the container has been tampered with.

[0033] Furthermore, it is preferable that the groove corresponding to the thin-walled portion 50 reach the lower end 33 of the tamper-evident portion 30. This is because when a container is tampered with, a finger or a tool is often inserted into the lower end 33 of the tamper-evident portion 30, and if the groove reaches the lower end 33, it is likely to become the starting point described above. In this embodiment, the groove corresponding to the thin-walled portion 50 ends when it reaches the locking portion 40, but the present invention is not limited to this, and it may end between the locking portion 40 and the lower end 33.

[0034] The width of the groove corresponding to the thin-walled portion 50 is preferably 1 mm or more from the viewpoint of improving tamper-evident properties, and is preferably 2 mm or less from the viewpoint of ensuring the rigidity of the tamper-evident portion 30. However, the present invention is not limited to this, and the width of the groove can be designed appropriately taking into consideration the strength of the material of the cap 1, etc. The width of the groove may be uniform or substantially uniform along the extension direction C2 of the groove, but the present invention is not limited to this.

[0035] 4, from the viewpoint of improving tamper evidence, the depth d of the groove corresponding to the thin-walled portion 50 may be deep enough to leave traces such as whitening or breakage when a malicious person inserts a finger or a tool into the lower end of the tamper-evident portion 30, and from the viewpoint of ensuring the rigidity of the tamper-evident portion 30, the depth d is preferably 50% or less of the thickness t of the tamper-evident portion 30. However, the present invention is not limited to this, and the groove depth d can be designed appropriately taking into account the strength of the material of the cap 1, etc. Note that the groove depth d may be uniform or substantially uniform along the extending direction C2 of the groove, but the present invention is not limited thereto.

[0036] In addition, when viewed from below in the tamper-evident portion 30, the cross-sectional shape of the groove corresponding to the thin-walled portion 50 is preferably an arc shape from the viewpoint of molding, but the present invention is not limited to this, and it may also be rectangular.

[0037] <2. Manufacturing method of synthetic resin cap> An example of a manufacturing method for the synthetic resin cap 1 according to this embodiment will be briefly described. The cap 1 can be manufactured by known or arbitrary injection or compression molding using a mold that molds the outer shape of the cap 1. Specifically, the cap 1 is obtained by forcing heated and molten synthetic resin into a mold that molds the outer shapes of the cap body 10, weakened line 20, tamper-evident portion 30, locking portion 40, thin-walled portion 50, etc. that make up the cap 1 at a predetermined injection pressure and then cooling the molded product. As mentioned above, examples of synthetic resins include polyethylene and polypropylene, but the present invention is not limited to these. If the cap 1 is colored other than white or transparent, the whitening described above becomes more pronounced, further improving tamper-evident properties.

[0038] In addition, instead of molding the outer shapes of the weakened line 20 and the thin-walled portion 50 in advance, the weakened line 20 and the thin-walled portion 50 may be formed by cutting the portions of the cap 1 corresponding to the weakened line 20 and the thin-walled portion 50 using a publicly known or any other method after the cap 1 is molded.

[0039] <3. Container> Referring to FIG. 1 , the container has a container mouth 2 onto which a cap 1 can be attached from above. The container mouth 2 has an overall cylindrical shape and is open at its top. The outer wall surface of the container mouth 2 preferably has a thread (e.g., a male thread) 3 that engages with a female thread 17 formed on the inner wall surface 16 of the skirt portion 12, a locking portion (so-called turnip) 4 located below the thread 3 and lockable with a locking portion 40 on the inner wall surface 31 of the tamper-evident portion 30, and a support ring 5 located below the locking portion 4. The locking portion 4 may include a curved surface that gradually expands in diameter downward from the container mouth 2 and a lower surface that is continuous with the curved surface and can abut against the upper surface 43 of the locking portion 40, or may have an overall jaw shape. The support ring 5 is used when transporting the container. The container may be made of a synthetic resin such as polyethylene terephthalate, or may be made of glass or metal, but the present invention is not limited thereto.

[0040] After a container is filled with contents such as a beverage, cap 1 is attached to container mouth 2 and seals the container mouth 2 as follows. That is, cap 1 covers container mouth 2 and is rotated in the closing direction. The closing direction is, for example, the clockwise direction when viewing cap 1 from above. As a result, internal thread 17 formed on skirt portion 12 of cap 1 screws into screw 3 on container mouth 2, and cap 1 rotates and descends relative to container mouth 2. As cap 1 descends further, locking portion 40 of tamper-evident portion 30 elastically expands from the radially inner side toward the outer side, climbing over locked portion 4 of container mouth 2, and its upper surface 43 abuts and locks against the lower surface of locked portion 4. Then, the annular protrusion 15 of the cap body 10 abuts against the upper surface of the container mouth 2, and the inner seal portion 13 and outer seal portion 14 of the cap body 10 abut against the inner and outer surfaces of the container mouth 2, thereby sealing the container mouth 2.

[0041] <4. Summary> As described above, the synthetic resin cap 1 according to this embodiment includes a cap body 10 including a top surface 11 and a skirt portion 12 extending from the periphery of the top surface 11, and a tamper-evident portion 30 connected to the skirt portion 12 via a breakable weakened line 20. The tamper-evident portion 30 also includes a locking portion 40 formed on an inner wall surface 31 of the tamper-evident portion 30 and capable of locking with the container opening 2, and a thin-walled portion 50 formed on the inner wall surface 31 of the tamper-evident portion 30 below the locking portion 40. According to this embodiment, even if the container is tamper-evidently opened, at least a portion of the outer wall surface 32 of the tamper-evident portion 30 will be deformed, destroyed, or whitened starting from the thin-walled portion 50, leaving a scar 51 on the outer wall surface 32 of the tamper-evident portion 30, thereby improving tamper evidence. Furthermore, the area where thin-walled portion 50 is formed is limited to the area below locking portion 40, which is a relatively strong portion of tamper-evident portion 30, and therefore it is possible to ensure the rigidity of tamper-evident portion 30. Therefore, in synthetic resin cap 1, the rigidity of tamper-evident portion 30 can be ensured while improving tamper evidence.

[0042] The above-described embodiment can be modified in various ways without departing from the spirit of the present invention. As one modification, the thin-walled portion 50 may be formed only on the outer wall surface 32 of the tamper-evident unit 30 below the locking portion 40. Alternatively, the thin-walled portion 50 may be formed only on the inner wall surface 31 and the outer wall surface 32 of the tamper-evident unit 30 below the locking portion 40. However, from the viewpoint of ensuring freedom of printing on the outer wall surface 32, it is preferable that the thin-walled portion 50 be formed only on the inner wall surface 31, as in the above-described embodiment. As another modification, the thin-walled portion 50 is not limited to the groove in the above-described embodiment, as long as it can serve as a starting point for deformation or the like when the container is tamper-evidently opened. For example, the thin-walled portion 50 may be a cut line formed below the locking portion 40 on the inner wall surface 31 and / or the outer wall surface 32 of the tamper-evident unit 30, leaving a portion of the tamper-evident unit 30 thin-walled. That is, the cut line does not penetrate the tamper-evident portion 30 in the thickness direction, and may be formed, for example, by appropriately cutting a portion of the cap 1 that corresponds to the thin-walled portion 50 after the cap 1 is molded. Note that other configurations can be similar to those of the above-described embodiment, and the explanations therefor are incorporated herein.

[0043] The above-described embodiments and modifications are merely examples, and various combinations of the embodiments and modifications may be made without departing from the spirit of the present invention. The above-described embodiments may also include optional components not shown in the drawings. Furthermore, the components shown in the drawings may be modified or omitted without departing from the spirit of the present invention. [Industrial Applicability]

[0044] The present invention can be suitably used in a synthetic resin cap that can improve tamper-evident properties while ensuring the rigidity of the tamper-evident portion. [Explanation of symbols]

[0045] 1: Synthetic resin cap 2: Container mouth 3: Screw 4:Locked part 5: Support ring 10: Cap body 11:Top part 12: Skirt section 13: Inner seal 14: Outer seal 15: Annular ridge 16: Inner wall surface 17:Female thread 18: Exterior wall 19: Anti-slip part 20: Weakened line 30: Tamper Evident Department 31: Inner wall surface 32: Exterior wall 33: Bottom edge 40: Locking part 41: Central area 42: Surrounding area 43:Top surface 44: Bottom surface 45: Corner 50: Thin section (groove) 51: Scar

Claims

1. a cap body including a top surface portion and a skirt portion extending from a periphery of the top surface portion; a tamper-evident portion connected to the skirt portion via a breakable weakened line; A synthetic resin cap comprising: The tamper-evident unit a locking portion formed on an inner wall surface of the tamper-evident portion and capable of being locked to a container opening; a thin-walled portion formed on an inner wall surface and / or an outer wall surface of the tamper-evident portion and below the locking portion; Including, Synthetic resin cap.

2. The locking portions are formed intermittently at predetermined intervals, The thin-walled portion is formed only on the inner wall surface and / or the outer wall surface corresponding to the hanging portion of the locking portion. The synthetic resin cap according to claim 1.

3. the locking portion has a central region including a region where the amount of radial inward protrusion of the tamper-evident portion is greatest, and a peripheral region extending from the central region along the circumferential direction of the tamper-evident portion and where the amount of protrusion decreases with increasing distance from the central region. The synthetic resin cap according to claim 2.

4. The thin-walled portion is formed only on the inner wall surface and / or the outer wall surface corresponding to the drooping portion of the central region. The synthetic resin cap according to claim 3.

5. The thin-walled portion is formed on the inner wall surface. The synthetic resin cap according to claim 1.

6. the thin-walled portion is a groove extending along the central axis of the tamper-evident portion, The synthetic resin cap according to claim 1.

7. The angle between the extension direction of the groove and the central axis is equal to or greater than 0 degrees and less than 30 degrees. The synthetic resin cap according to claim 6.

8. the groove reaches the lower end of the tamper-evident portion; The synthetic resin cap according to claim 6 or 7.

9. In a cross-sectional view passing through a central axis of the tamper-evident part, the locking part includes an upper surface along the top surface part and a lower surface inclined radially from the upper surface toward a lower end of the tamper-evident part, An internal thread is formed on the inner wall surface of the skirt portion to be threadedly engaged with the thread of the container opening portion. The synthetic resin cap according to claim 1.

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