JP7820183B2 - Synthetic resin container lid - Google Patents

Description

The present invention relates to a synthetic resin container lid.

The present invention relates to a synthetic resin container lid in which a locking means consisting of multiple locking protrusions extending circumferentially or a continuously extending annular locking ridge is formed on the inner peripheral surface of the tamper-evident bottom portion of the skirt wall.

As is well known, a widely used container lid for a container made of glass, synthetic resin, or sheet metal has a cylindrical neck portion with a male thread on the outer peripheral surface and a locking jaw located below the male thread. The container lid has a circular top wall and a cylindrical skirt wall depending from the periphery of the top wall. The skirt wall has a circumferentially extending fracture line formed therein, which is composed of circumferentially extending slits spaced apart along the periphery and bridging portions between the slits. The skirt wall is divided into a main skirt portion above the fracture line and a tamper-evident skirt portion below the fracture line. An internal thread is formed on the inner peripheral surface of the main skirt portion, and a locking means is formed on the inner peripheral surface of the tamper-evident skirt portion. The locking means consists of multiple locking projections that project radially inward and extend circumferentially, or an annular locking ridge that projects radially inward and extends continuously circumferentially. The inner peripheral edge of the main part of the locking means continues circumferentially along the inner peripheral surface of the tamper-evident skirt.

When sealing the neck of a container filled with contents, the container lid is fitted onto the neck and rotated in the closing direction, threading the female thread of the lid onto the male thread of the neck. When the container lid is thus attached to the neck as required, the locking means of the container lid resiliently overcomes the locking jaw of the neck and is positioned below it. When the neck is opened to consume the contents of the container, the container lid is rotated in the opening direction. This causes the container lid to rise relative to the neck as the male thread and female thread disengage. When the container lid is raised slightly, the locking means of the container lid engages with the locking jaw of the neck, thereby preventing the tamper-evident skirt from rising. As the container lid continues to rotate in the opening direction, the circumferential rupture line formed on the skirt wall ruptures, and the tamper-evident bottom portion of the skirt wall separates from the main skirt portion (or, if an axial rupture line is formed on the tamper-evident bottom portion, the axial rupture line ruptures, and the tamper-evident bottom portion unfolds from an endless ring shape into an ended band shape, and the tamper-evident bottom portion remains connected to the main skirt portion along part of the circumferential direction without being completely separated from the main skirt portion). As the container lid continues to rotate in the opening direction, the container lid (or the entire container lid including the tamper-evident bottom portion) is detached from the neck portion, leaving the tamper-evident bottom portion behind, and the neck portion is opened.

In recent years, there has been a demand to reduce the amount of material used to manufacture container lids in order to reduce environmental impact and manufacturing costs. Patent Document 1 below discloses an example of a container lid that reduces the amount of material used by providing multiple lightening holes at intervals around the circumference on the upper surface of the locking means.

Japanese Patent Application Laid-Open No. 2020-70031

In the container lid disclosed in Patent Document 1, when the locking means elastically overcomes the locking jaw of the neck portion during the process of attaching the container lid to the neck portion of the container, there is a large resistance when the locking means elastically overcomes the locking jaw due to the large contact area between the underside of the locking means and the upper surface of the locking jaw. Therefore, when the locking means elastically overcomes the locking jaw during the above process, the main skirt portion tends to rotate relative to the tamper-evident bottom portion, which could cause the bridge portion connecting the main skirt portion and the tamper-evident bottom portion to be stretched and broken. Furthermore, because of this large resistance, equipment is required to properly attach the container lid to the neck portion of the container, which could increase manufacturing costs and reduce manufacturing efficiency.

The present invention was made in light of the above facts, and its main technical objective is to provide a new and improved synthetic resin container lid that reduces the amount of material used to manufacture the container lid, while also reducing the resistance when the locking means elastically overcomes the locking jaws of the neck portion during the process of attaching the container lid to the neck portion of the container.

After extensive research, the inventors discovered that the above-mentioned main technical problem could be solved by providing a lightening hole not only on the top surface but also on the bottom surface of the locking means.

That is, according to 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 hanging down from the periphery of the top wall, the skirt wall having a circumferentially extending fracture line made up of a plurality of circumferentially extending slits spaced apart in the circumferential direction and a plurality of bridging portions existing between the slits, the skirt wall being partitioned into a skirt main portion above the fracture line and a tamper-evident hem portion below the fracture line, a female thread formed on the inner peripheral surface of the skirt main portion, and locking means arranged on the inner peripheral surface of the tamper-evident hem portion comprising a plurality of locking protrusions that protrude radially inward and extend circumferentially or an annular locking ridge that protrudes radially inward and extends continuously in the circumferential direction, the locking means having a main portion whose inner peripheral edge is continuous in the circumferential direction and parallel to the inner peripheral surface of the tamper-evident hem portion,
The synthetic resin container lid is characterized in that a plurality of recesses are formed at intervals in the circumferential direction on the underside of the main portion.

The lower surface of the main portion is preferably inclined downwardly and radially outwardly to be connected to the inner peripheral surface of the tamper-evident hem portion. Preferably, when the locking means is composed of a plurality of the locking projections, the inner peripheral edges of the ends on both circumferential sides of the locking projections are inclined radially outwardly from the circumferential ends of the inner peripheral edge of the main portion to be connected to the inner peripheral surface of the tamper-evident hem portion. In this case, the lower surfaces of the ends are preferably provided with reinforcing portions whose inner diameter gradually increases downwardly to be connected to the inner peripheral surface of the tamper-evident hem portion.

In this invention, due to the provision of a lightening portion on the underside of the locking means, the amount of material used to manufacture the container lid is reduced, and when the locking means elastically climbs over the locking jaw of the neck portion during the process of attaching the container lid to the neck portion of the container, the contact area between the underside of the locking means and the locking jaw is reduced, thereby reducing the resistance torque and the force required to climb over. Furthermore, if the inner peripheral edge of the main portion of the locking means is continuous circumferentially and parallel to the inner peripheral surface of the tamper-evident hem, the locking protrusion is less likely to deform, i.e., the locking protrusion has sufficient rigidity.

1 is a view showing a preferred embodiment of a synthetic resin container lid constructed according to the present invention, partially in cross section; FIG. 2 is a bottom view of the container lid shown in FIG. 1 . 2 is a partially enlarged view of the container lid shown in FIG. 1 and the neck of the container to which the lid is attached. FIG. 2 is a developed view showing the inner peripheral surface of the tamper-evident bottom portion of the container lid shown in FIG. 1 . FIG. 10 is a developed view showing the inner peripheral surface of the tamper-evident bottom portion in a modified example of a container lid configured according to the present invention. FIG.

The present invention will now be described in further detail with reference to the accompanying drawings, which show a preferred embodiment of a synthetic resin container lid constructed in accordance with the present invention.

Referring to Figures 1 and 2, the 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 periphery of the top wall 4. A relatively long, tubular inner seal piece 8 and a relatively short, tubular outer seal piece 10 depending downward are formed on the inner peripheral edge of the top wall 4. A small, annular rib 12 is also formed between the inner seal piece 8 and the outer seal piece, protruding slightly downward from the inner surface of the top wall 4.

A circumferentially extending fracture line 14 is formed on the skirt wall 6, and the skirt wall 6 is divided into a main skirt portion 16 above the fracture line 14 and a tamper-evident hem portion 18 below the fracture line 14. The fracture line 14 is composed of a plurality of circumferentially extending slits (kerfs) 20 spaced apart in the circumferential direction and a plurality of bridging portions 22 between the slits 20, and the tamper-evident hem portion 18 is connected to the main skirt portion 16 via the plurality of bridging portions 22.

Anti-slip knurling 24 consisting of alternating concave and convex shapes is formed on the outer peripheral surface of the skirt main portion 16 when viewed circumferentially. A female thread 26 is formed on the inner peripheral surface of the skirt main portion 16 of the skirt wall 6. The female thread 26 has multiple notches 28 spaced circumferentially.

1 and 2, as well as 3 and 4, a locking means is disposed on the inner peripheral surface of the tamper-evident hem 18. In the illustrated embodiment, the locking means is composed of a plurality of (five in the illustrated embodiment) locking protrusions 32 that protrude radially inward and extend circumferentially. The locking protrusions 32 are divided into a main portion 34 whose inner peripheral edge is circumferentially continuous and parallel to the inner peripheral surface of the tamper-evident hem 18, and end portions 36 located on both circumferential sides of the main portion 34, whose inner peripheral edges are inclined radially outward from the circumferential end of the inner peripheral edge of the main portion 34 toward the outside in the circumferential direction and connected to the inner peripheral surface of the tamper-evident hem 18. As shown in Figure 3, the upper surface of the main portion 34 of the locking projection 32 is divided into an upper locking surface 38 located radially inward and extending substantially horizontally, and an upper mating surface 40 located radially outward, with an inner diameter gradually increasing upward and connected to the inner peripheral surface of the tamper-evident hem portion 18. In the illustrated embodiment, the vertical cross-sectional shape of the upper mating surface 40 extends linearly upward and then slopes radially outward. Meanwhile, the lower surface 42 of the main portion 34 of the locking projection 32 slopes radially outward and downward to connect to the inner peripheral surface of the tamper-evident hem portion 18. As can be understood by referring to Figures 1 and 4, a plurality of lightening holes 44 are formed at intervals in the circumferential direction on the lower surface 42 of the main portion 34. The recessed portions 44 are formed by cutting out the underside 42 of the main portion 34 so as to expose the inner circumferential surface of the tamper-evident bottom portion 18, and the underside of the cutout portion is substantially horizontal. Referring to FIG. 4 , in the illustrated embodiment, four recessed portions 44 are formed at equal intervals in the circumferential direction, and all have the same circumferential width. Since the recessed portions 44 are equally spaced in the circumferential direction and have the same circumferential width, the effect of reducing the resistance torque and the resistance to climbing over the locking protrusions 32 when climbing over the locking jaws during the process of attaching the container lid 2 to the mouth and neck of the container is achieved uniformly in the circumferential direction, as described below. Furthermore, the circumferential width of each recessed portion 44 is wider than the circumferential width of a remaining portion 50 remaining between two adjacent recessed portions 44, and the remaining portion 50 is rib-shaped. The upper surface of the end 36 of the locking projection 32 has an inner diameter that gradually increases upward and is connected to the inner peripheral surface of the tamper-evident hem 18, and is circumferentially continuous with the upper locking surface 38 and upper mating surface 40 of the main portion 23. The lower surface of the end 36 is provided with a lower reinforcing portion 52, whose inner diameter gradually increases downward and is connected to the inner peripheral surface of the tamper-evident hem 18; the lower surface of the end 36 is not hollowed out. In the illustrated embodiment, the inner diameter of the lower reinforcing portion 52 gradually increases radially away from the main portion 34. The lower edge of the lower surface of the end 36 is gradually inclined upward and outward in the circumferential direction. The inner surface of the tamper-evident hem 18 also has a ridge 54 that extends continuously circumferentially between two circumferentially adjacent locking projections 32. Both circumferential ends of the ridge 46 are connected to the circumferential end faces of the locking projections 32.

In Figure 1, the container neck 100 is shown by a two-dot chain line along with the container lid 2. The container neck 100, which can be formed from a suitable synthetic resin such as polyethylene terephthalate, glass, or thin metal plate, is cylindrical overall, and the outer surface of the neck 100 is formed with a male thread 102 and a locking jaw 104 located below the male thread 102. The locking jaw 104 has an arcuate upper surface whose outer diameter gradually increases downward, a cylindrical outer surface, and a lower surface that extends substantially horizontally. A support ring 106 (such a support ring 106 is used for transporting the container, as is well known to those skilled in the art) is also arranged on the outer surface of the neck 100 and located below the locking jaw 104.

After the contents are filled into the container, the container lid 2 is fitted onto the neck portion 100 and rotated in the closing direction (clockwise as viewed from above in Figure 1) to thread the female thread 26 of the container lid 2 onto the male thread 102 of the neck portion 100. When the female thread 26 is threaded onto the male thread 102 to the state shown in Figure 1, the inner seal piece 8 of the container lid 2 enters the neck portion 100 and is tightly contacted with the inner peripheral surface of the neck portion 100, the outer seal piece 10 is tightly or closely adjacent to the outer peripheral surface of the neck portion 100, and the annular micro-ridge 12 is tightly contacted with the top surface of the neck portion 100, thus sealing the neck portion 100. The locking protrusion 32 disposed on the inner peripheral surface of the tamper-evident skirt 18 elastically overcomes the locking jaw 104 of the mouth and neck portion 100 (i.e., by elastic deformation or displacement of the tamper-evident skirt 18) and is positioned below the locking jaw 104. When the locking protrusion 32 elastically overcomes the locking jaw 104 of the mouth and neck portion 100, the lower surface 42 of the locking protrusion 32 is inclined downward and radially outward, allowing the tamper-evident skirt 18 to be smoothly elastically deformed. In this state, as can be understood by referring to Figures 3 together with Figure 1, the mating upper surface 40 of the locking protrusion 32 comes into contact with or is in close contact with the lower end of the outer peripheral surface of the locking jaw 104 of the mouth and neck portion 100.

In the present invention, due to the provision of the recessed portion 44 on the underside 42 of the locking protrusion 32, the amount of material used to manufacture the container lid is reduced. Furthermore, when the locking protrusion 32 elastically overcomes the locking jaw portion 104 of the container neck portion 100 during the process of attaching the container lid 2 to the container neck portion 100, the contact area between the underside 42 of the locking protrusion 32 and the locking jaw portion 104 is reduced, thereby reducing the resistance torque and the force required for the override. Because the inner peripheral edge of the main portion 34 of the locking protrusion 32 is circumferentially continuous and parallel to the inner peripheral surface of the tamper-evident bottom portion 18, the locking protrusion 32 is less likely to deform, i.e., the locking protrusion 32 has sufficient rigidity. Furthermore, the provision of the lower reinforcing portion 52 on the underside 42 of the end portion 36 also contributes to the locking protrusion 32 having sufficient rigidity.

When opening the neck portion 100 to consume the contents, the container lid 2 is rotated in the opening direction, i.e., counterclockwise when viewed from above in Figure 1. This gradually disengages the male thread 102 from the female thread 26, and the tamper-evident skirt portion 18, along with the skirt main portion 16, is raised relative to the neck portion 100 as the rotation proceeds. At this time, as can be seen from Figure 2, the upper mating surface 40 of the locking projection 32 on the tamper-evident skirt portion 18 is brought into close contact with the lower end of the outer circumferential surface of the locking jaw portion 104 of the neck portion 100, gradually increasing the frictional resistance torque. When the container lid 2 is raised a predetermined amount relative to the neck portion 100, the upper locking surface 38 of the locking projection 32 locks against the lower surface of the locking jaw 104, preventing the tamper-evident hem 18 from moving upward in the axial direction. At this time, the upper mating surface 40 of the locking projection 32 is in close contact with the lower end of the outer circumferential surface of the locking jaw 104 of the neck portion 100, so that the tamper-evident hem 18 is firmly held by the locking jaw 104. Then, because the tamper-evident hem 18 is prevented from moving upward in the axial direction, stress is generated in the bridging portion 22 of the break line 14, causing the bridging portion 22 to break, and the tamper-evident hem 18 is separated from the main skirt portion 16. After the break line 14 is broken, the tamper-evident bottom 18 remains in the neck portion 100, and the top wall 4 of the container lid 2 and the main skirt portion 16 of the skirt wall 6 are rotated and freely moved axially upward, separating them from the neck portion 100, thereby opening the neck portion 100. If desired, an axial break line can be formed in the tamper-evident bottom 18, so that when the neck portion 100 of the container is opened, the axial break line is broken, while a portion of the circumferentially extending break line 14 remains unbroken, causing the tamper-evident bottom 18 to expand from an endless annular shape into an ended annular shape, allowing the entire container lid 2 to be separated from the neck portion 100 together with the tamper-evident bottom 18.

In the above-described embodiment, the locking means is composed of multiple locking protrusions that protrude radially inward and extend circumferentially. However, as shown in the modified example in Figure 5, the locking means may be composed of a single annular locking ridge 32a that protrudes radially inward and extends continuously circumferentially. When the locking means is composed of an annular locking ridge 32a, the entire annular locking ridge 32a becomes the main portion 34a of the locking means, and multiple lightening holes 44a are formed at intervals in the circumferential direction on the underside 42a of the main portion 34a.

The above describes in detail a preferred embodiment of the container lid of the present invention with reference to the accompanying drawings. However, the present invention is not limited to the above embodiment, and further modifications may be made within the scope of the present invention. For example, in the illustrated embodiment, the upper surface of the locking means is provided with an upper engaging surface whose inner diameter gradually increases upward and which connects to the inner peripheral surface of the tamper-evident bottom portion, as well as an upper engaging surface that extends approximately horizontally. However, the upper engaging surface may be omitted, and the entire upper surface of the locking means may serve as the upper engaging surface. The lower surface of the locking means may also be substantially horizontal. Furthermore, while the shape of the lightening portion 44 is rectangular in the examples and modified examples, it may also be curved, such as by connecting the lower ends of the remaining portions in an arc shape when viewed circumferentially.

2: Container lid 4: Top wall 6: Skirt wall 14: Breaking line 16: Main skirt portion 18: Tamper-evident bottom portion 20: Slit 22: Bridge portion 26: Female thread 32: Locking protrusion (locking means)
34: Main portion (of the locking projection) 40: Fitting upper surface (of the main portion of the locking projection) 42: Lower surface (of the main portion of the locking projection) 44: Lightening portion

Claims (4)

a synthetic resin container lid comprising a circular top wall and a cylindrical skirt wall depending from the periphery of the top wall, the skirt wall having a circumferentially extending fracture line formed therein, the circumferentially extending fracture line being made up of a plurality of circumferentially spaced slits and a plurality of bridging portions between the slits, the skirt wall being partitioned into a main skirt portion above the fracture line and a tamper-evident hem portion below the fracture line, the main skirt portion having an internal thread formed on its inner peripheral surface, and the tamper-evident hem portion having an inner peripheral surface provided with a locking means made up of a plurality of locking projections that protrude radially inward and extend circumferentially or an annular locking ridge that protrudes radially inward and extends continuously in the circumferential direction, the locking means having a main portion whose inner peripheral edge is continuous in the circumferential direction and parallel to the inner peripheral surface of the tamper-evident hem portion,
A synthetic resin container lid characterized in that a plurality of recesses are formed at intervals in the circumferential direction on the underside of the main portion. 2. The synthetic resin container lid according to claim 1 , wherein the lower surface of the main portion is inclined downward and radially outward to be connected to the inner peripheral surface of the tamper-evident bottom portion. A synthetic resin container lid as described in claim 1 or 2, wherein when the locking means is composed of a plurality of locking protrusions, the inner peripheral edges of the ends on both sides of the circumferential direction of the locking protrusions are connected to the inner peripheral surface of the tamper-evident bottom portion, inclining radially outward from the circumferential end of the inner peripheral edge of the main portion toward the outside in the circumferential direction. 4. The synthetic resin container lid according to claim 3 , wherein a reinforcing portion is provided on the lower surface of the end portion, the inner diameter of which gradually increases downward and which is connected to the inner peripheral surface of the tamper-evident bottom portion.