Synthetic resin container lid

Abstract

To provide a new hinge cap by which tamper-evident performance is prevented from being damaged.SOLUTION: Elastic lock means 66 extending upward is arranged on an upper surface of a locking wall 38, and a locking recess part 72 whose lower surface is opened is formed on an inner surface of a skirt wall 54, to constitute a tamper-evident mechanism by the elastic lock means 66 and the locking recess part 72. When an upper lid 6 is turned to a closed position for the first time, the elastic lock means 66 is housed in the locking recess part 72, and a locked protruding line 62 formed on the upper lid 6 is locked on a locking protruding line 40. When the upper lid 6 is turned to the closed position after once the upper lid 6 is turned from the closed position to an opened position, the elastic lock means 66 is brought into contact with a locking lower surface 74 defined on both sides in a circumferential direction of the locking recess part 72 without being housed in the locking recess part 72, and the locked protruding line 62 is locked on an auxiliary locking protruding line 68 positioned above the locking protruding line 40.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a container lid having a lid body and a top cover connected to the lid body via hinge means and rotatable between a closed position that covers the top surface of the lid body and an open position that exposes the top surface of the lid body. [Background technology]

[0002] A typical example of a synthetic resin container lid, a so-called hinge cap, is shown in Patent Document 1 below. The lid body has a lid body and a top lid connected to the lid body via hinge means and rotatable between a closed position that covers the top surface of the lid body and an open position that exposes the top surface of the lid body. The lid body has a closing wall and a cylindrical mounting wall hanging down from the periphery of the closing wall. A cylindrical locking wall is disposed on the outer periphery of the top surface of the closing wall, and a locking rib is formed on the upper end of the outer periphery of the locking wall. The top lid has a top wall and a cylindrical skirt wall hanging down from the periphery of the top wall. The inner periphery of the skirt wall has a lower end formed with a locking rib that is locked by a locking rib formed on the lid body when the top lid is rotated to the closed position.

[0003] The container lid disclosed in Patent Document 1 below further includes a tamper-evident mechanism, a mechanism that clearly indicates that the lid has been opened. This tamper-evident mechanism includes a tamper-evident piece connected to the skirt wall of the lid via a breakable weakened portion. A locking means is formed on the outer surface of the tamper-evident piece, and a locking means is formed on the outer surface of the mounting wall of the lid body. When the lid is rotated from the open position to the closed position, the locking means elastically overcomes the locking means and locks onto it. When an upward force is applied to the lid to rotate it from the closed position to the open position, the locking means locks onto the locking means, preventing the lid from rotating in the open direction, and stress is concentrated on the breakable weakened portion. When the breakable weakened portion is broken by the applied stress, the tamper-evident piece separates from the top lid, causing the top lid to pivot in the opening direction. The separation of the tamper-evident piece from the top lid clearly indicates that the top lid has been opened. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2022-57273 Summary of the Invention [Problem to be solved by the invention]

[0005] Therefore, in the synthetic resin container lid shown in Patent Document 1, the locking means and lockable means that constitute the tamper-evident mechanism are formed on the outer surface of the container lid, and therefore when a large number of container lids are stored in a container or the like and transported, the locking means and lockable means may collide with other container lids and be damaged, and tamper-evident performance may not be ensured.

[0006] The present invention has been made in view of the above-mentioned circumstances, and its main technical object is to provide a novel hinge cap that prevents the tamper-evident performance from being impaired. [Means for solving the problem]

[0007] After extensive research, the inventors have found that the above-mentioned main technical problem can be solved by arranging an upwardly extending elastic locking means on the upper surface of the locking wall and forming an locking recess with an open lower surface on the inner surface of the skirt wall, so that the elastic locking means and the locking recess form a tamper-evident mechanism; when the top cover is first rotated to the closed position, the elastic locking means is accommodated in the locking recess and the locking protrusion formed on the top cover is engaged with the locking protrusion; however, once the top cover is rotated from the closed position to the open position and then rotated to the closed position, the elastic locking means is not accommodated in the locking recess but abuts against the locking lower surfaces defined on both circumferential sides of the locking recess, and the locking protrusion is engaged with the auxiliary locking protrusion located above the locking protrusion.

[0008] According to the present invention, as a synthetic resin container lid for solving the above main technical problems, it comprises a lid body and an upper lid that is connected to the lid body via hinge means and is rotatable between a closed position covering the upper surface of the lid body and an open position exposing the upper surface of the lid body. The lid body includes a closing wall and a cylindrical mounting wall hanging down from the periphery of the closing wall. A cylindrical locking wall is disposed on the outer peripheral edge of the upper surface of the closing wall, and a locking ridge is formed on the outer peripheral surface of the locking wall. The upper lid includes a top wall and a cylindrical skirt wall hanging down from the periphery of the top wall. At the lower end of the inner peripheral surface of the skirt wall, when the upper lid is rotated to the closed position, a locked ridge that is locked to the locking wall formed on the lid body is formed. In the synthetic resin container lid, Elastic locking means extending upward is disposed on the upper surface of the locking wall. Above the locked ridge on the inner surface of the skirt wall, a thickened portion where the inner diameter of the skirt wall is reduced is provided. A locking recess with an open bottom surface is formed on the inner surface of the thickened portion, and locking lower surfaces are defined on both circumferential sides of the locking recess. An auxiliary locking ridge is disposed at the upper end of the outer peripheral surface of the locking wall. When the tip of the elastic locking means is received in the locking recess and the upper lid is in the closed position, the initial state is such that in the initial state, the locked ridge is locked to the locking ridge. When the upper lid is rotated in the opening direction from the initial state toward the open position, the locked ridge elastically overrides the locking ridge and the auxiliary locking ridge, and at the same time, the elastic locking means is released from the locking recess. After the elastic locking means is released from the locking recess and the upper lid is rotated in the closing direction toward the closed position, the elastic locking means is brought into contact with the locking lower surface, and the locked ridge is locked to the auxiliary locking ridge. A synthetic resin container lid is provided, which is characterized by the above.

[0009] Preferably, the elastic locking means is a pair of elastic locking pieces arranged close to each other in the circumferential direction, and each of the pair of elastic locking pieces extends upward from the upper surface of the closing wall at a distance from each other. The elastic locking means are preferably arranged on both sides in a diameter direction extending perpendicular to a line connecting the circumferential center of the hinge means and the center of the closing wall in a plan view. Preferably, the locked rib and the auxiliary locking rib are both annular in shape and extend continuously in the circumferential direction. [Effects of the Invention]

[0010] In a container lid constructed according to the present invention, in the initial state, the engaging protrusion is engaged with the locking protrusion, so there is no gap between the underside of the skirt wall and the upper surface of the closing wall, or if there is a gap, it is very small. However, when the top lid is rotated in the opening direction from the initial state and the elastic locking means is released from the locking recess, and then the top lid is rotated again in the closing direction toward the closed position, the elastic locking means abuts the locking lower surface, and the engaging protrusion is engaged not with the locking protrusion but with the auxiliary locking protrusion formed on its upper surface, so a relatively large gap is formed between the underside of the skirt wall and the upper surface of the closing wall, and the presence of such a gap clearly indicates that the top lid has been opened. In other words, in a container lid constructed according to the present invention, the elastic locking means extending upward from the upper surface of the locking wall and the locking recess provided on the inner surface of the skirt wall constitute a tamper-evident mechanism, and since the tamper-evident mechanism is arranged on the inside of the container lid, the tamper-evident mechanism will not be damaged when a large number of container lids are stored in a container or the like and transported. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a perspective view of a preferred embodiment of a synthetic resin container lid constructed in accordance with the present invention, with the top lid in an open position; [Figure 2] FIG. 2 is a plan view of the state shown in FIG. [Figure 3] 2 is a front view of the state shown in FIG. 1, with the top cover omitted. FIG. [Figure 4] FIG. 2 is a right side view of the state shown in FIG. 1. [Figure 5] Central longitudinal sectional view of FIG. 4. [Figure 6] Right side view of the container lid shown in FIG. 1 when in the initial state. [Figure 7] Rear view of the container lid shown in FIG. 1 when in the initial state. [Figure 8] Central longitudinal sectional view of FIG. 6. [Figure 9] Central longitudinal sectional view after the upper lid is pivoted to the open position and the pull ring is removed from the state shown in FIG. 8. [Figure 10] Right side view when the upper lid is pivoted back to the closed position from the state shown in FIG. 9. [Figure 11] Central longitudinal sectional view of FIG. 10.

Embodiments for Carrying Out the Invention

[0012] Hereinafter, with reference to the accompanying drawings showing preferred embodiments of a synthetic resin container lid configured according to the present invention, it will be described in more detail. Here, the vertical direction in this specification is based on the state where the upper lid is in the closed position described later, unless otherwise specified. Therefore, when the upper lid is in the open position described later, the vertical direction is reversed.

[0013] Referring to FIG. 1 for explanation, a synthetic resin container lid indicated as a whole by reference numeral 2 includes a lid body 4 and an upper lid 6, and the lid body 4 and the upper lid 6 are connected via hinge means 7. The container lid 2 is integrally molded in the state shown in FIG. 1, that is, the state where the upper lid 6 is in the open position described later.

[0014] 2 and 5, the lid body 4 has a closing wall 10 and a cylindrical mounting wall 12 that hangs down from the periphery of the closing wall 10. The closing wall 10 is circular in plan view, i.e., in FIG. 2, and is defined as a removal area 16 surrounded by a breakable thin-wall line 14 and a remaining area 18 outside the breakable thin-wall line 14. The breakable thin-wall line 14 is configured as an annular groove formed on the underside of the closing wall 10. The removal area 16 is located at the center of the closing wall 10 and is defined as a circular central portion 20 and a pair of extension portions 22a and 22b that locally extend radially outward from the outer circumferential surface of the central portion 20 toward the side where the hinge means 7 is located and the opposite side, respectively. A well-known pull ring 24 is connected to the upper surface of the extension portion 22a.

[0015] An upwardly extending, generally cylindrical pouring guide wall 36 is disposed on the upper surface of the closing wall 10 at the outer peripheral edge of the remaining area 18. The upper end of the pouring guide wall 36 is curved radially outward. A cylindrical locking wall 38 is disposed on the upper surface of the closing wall 10 outside the pouring guide wall 36, and an annular locking protrusion 40 is formed on the outer peripheral surface of the locking wall 38. A downwardly hanging, cylindrical sealing wall 42 is formed on the lower surface of the closing wall 10 at the outer peripheral edge of the remaining area 18, and the outer peripheral surface of the sealing wall 42 faces the inner peripheral surface of the mounting wall 12 at a radial distance.

[0016] 5, a locking means 46 that protrudes radially inward is disposed at the lower end of the inner peripheral surface of the mounting wall 12. In the illustrated embodiment, the locking means 46 is configured as an annular ridge that extends continuously in the circumferential direction. Referring to FIGS. 1 and 3, a recess 48 that is substantially rectangular in front view and whose outer diameter is reduced continuously in the circumferential direction is formed in the upper part of the outer peripheral surface of the mounting wall 12 on the diametrically opposite side from the hinge means 7.

[0017] 2 and 5, the top cover 6 has a circular top wall 52 extending substantially horizontally and a cylindrical skirt wall 54 depending from the periphery of the top wall 52. The lower end of the outer periphery of the skirt wall 54 is connected to the upper end of the outer periphery of the mounting wall 12 of the lid body 4 via hinge means 7, so that the top cover 6 can freely pivot between a closed position (e.g., the state shown in FIG. 8) in which it covers the closing wall 10 of the lid body 4 and an open position (e.g., the state shown in FIG. 5) in which it exposes the closing wall 10 of the lid body 4. A cylindrical depending wall 58 depending downward is formed at the outer periphery of the lower surface of the top wall 52. A flange 60 protruding radially outward is provided at a location on the lower end of the outer periphery of the skirt wall 54, diametrically opposite to the hinge means 7, and can be hooked on by a finger when pivoting the top cover 6 open or closed. A circumferentially extending engagement rib 62 is disposed on the lower end of the inner peripheral surface of the skirt wall 54. In the illustrated embodiment, the engagement rib 62 has a circular ring shape that extends continuously in the circumferential direction. A downward-facing circular ring-shaped abutment shoulder surface 64 is formed above the engagement rib 62.

[0018] 1 to 9, the hinge means 7 includes a central connecting piece 8 and a pair of band-shaped outer connecting pieces 9 arranged on either side of the central connecting piece 8. Mainly referring to Fig. 8, the central connecting piece 8 includes an upper connecting piece 8a extending radially outward from the lower end of the outer peripheral surface of the skirt wall 54 and a lower connecting piece 8b extending radially outward from the upper end of the outer peripheral surface of the mounting wall 12, and the radially outer end of the upper connecting piece 8a is connected to the radially outer end of the lower connecting piece 8b. The upper connecting piece 8a includes a thick-walled base end side portion 8a-1 and a thin-walled connecting end side portion 8a-2, and the lower connecting piece 8b includes a thick-walled base end side portion 8b-1 and a thin-walled connecting end side portion 8b-2. When the top cover 6 is in the initial state described below (the top cover 6 is in the closed position and the engaging protrusion 62 is engaged with the engaging protrusion 40), the lower surface of the upper connecting piece 8a and the upper surface of the lower connecting piece 8b are both flat over their entirety and face each other.

[0019] As shown in FIGS. 1 to 4 , in the lid body 4 of a container lid constructed according to the present invention, an upwardly extending elastic locking means 66 is formed on the upper surface of the locking wall 38. In the illustrated embodiment, the elastic locking means 66 are arranged on both sides of the diameter extending perpendicular to a line connecting the circumferential center of the hinge means 7 and the center of the closure wall 10 in a plan view. The elastic locking means 66 is a pair of elastic locking pieces 66a and 66b arranged closely in the circumferential direction, and each of the pair of elastic locking pieces 66a and 66b extends upward from the upper surface of the locking wall 38 in directions separating from each other. More specifically, the elastic locking piece 66b extends toward the hinge means 7, while the elastic locking piece 66a extends toward the opposite side. Furthermore, an auxiliary locking protrusion 68 is arranged on the upper end of the outer peripheral surface of the locking wall 38. In the illustrated embodiment, the auxiliary locking protrusion 68 has a circular shape extending continuously in the circumferential direction. If desired, the auxiliary locking ribs 68 may have a circular arc shape extending in the circumferential direction. Furthermore, as shown in FIGS. 1 and 2 , in the top lid 6 of the container lid constructed according to the present invention, a thickened portion 70 is provided on the inner surface of the skirt wall 54 above the locking ribs 62, where the inner diameter of the skirt wall 54 is reduced. A locking recess 72 with an open lower surface is formed on the inner surface of the thickened portion 70, and locking lower surfaces 74 are defined on both circumferential sides of the locking recess 72. In the illustrated embodiment, the thickened portion 70 is provided over the entire circumferential direction, and the locking lower surfaces 74 extend substantially horizontally. The locking recesses 72 are rectangular and are located on both diametrical sides of a line connecting the circumferential center of the hinge means 7 and the center of the top wall 52 in a plan view. If desired, the thickened portion 70 may be formed locally in a desired circumferential region.

[0020] As described above, the container lid 2 is integrally formed with the upper lid 6 in the open position, and after molding, the upper lid 6 is pivoted from the open position to the closed position. At this time, the tip portions of the pair of elastic locking pieces 66a and 66b are brought closer to each other by a required guiding jig (not shown), and as shown by the broken line in FIG. 6, they are accommodated in the locking recess 72. When the pair of elastic locking pieces 66a and 66b are guided into the locking recess 72, the required jig is detached from the container lid. Then, when the upper lid 6 is pivoted to the closed position, as shown in FIG. 8, the abutting shoulder surface 64 formed on the inner surface of the skirt wall 54 of the upper lid 6 abuts on the upper surface of the locking wall 38 of the lid body 4, and the locked protrusion 62 elastically rides over the auxiliary locking protrusion 68 and the locking protrusion 40 located below it and is locked to the locking protrusion 40, and the upper lid 6 is held in the closed position. This state, that is, the state where the tip portion of the elastic locking means 66 is accommodated in the locking recess 72 and the upper lid 6 is in the closed position, is taken as the initial state. The container lid 2 is conveyed in the initial state.

[0021] FIG. 8 also shows, in a two-dot chain line, the mouth-neck portion of the container to which such a container lid 2 according to the present invention is applied, together with the container lid 2. The mouth-neck portion 100 of the container, which can be formed of an appropriate synthetic resin or glass, has a cylindrical shape with an open upper surface, and a fitting protrusion 102 is formed on the upper end portion of its outer peripheral surface. Further, a support ring 104 (this support ring 104 is used when conveying the container) is also formed on the outer peripheral surface of the mouth-neck portion 100, below the fitting protrusion 102.

[0022] When the container lid 2 is attached to the mouth-neck portion 100 to seal the mouth-neck portion 100 after the container is filled with the contents, the container lid 2 in the initial state is fitted over the mouth-neck portion 100 and forced downward. Then, the locking means 46 formed on the inner peripheral surface of the mounting wall 12 elastically rides over the fitting protrusion 102 of the mouth-neck portion 100 and is locked thereto.

[0023] When discharging the contents of the container, first, place a finger on the lower surface of the flange portion 60 of the upper lid 6 and apply an upward force with the hinge means 7 as the pivot point to elastically overcome the locking protrusion 40 formed on the outer peripheral surface of the locking wall 38 of the lid body 4 and the auxiliary locking protrusion 68 on the inner peripheral surface of the skirt wall 54 of the upper lid 6 at the locked protrusion 62. Next, pivot the upper lid 6 in the opening direction around the hinge means 7 to the open position. While the upper lid 6 is being pivoted from the closed position to the open position, the elastic locking means 66 is released from the locking recess 72. After the upper lid 6 is pivoted to the open position, place a finger on the pull ring 24 of the lid body 4 and force it upward to break the breakable thin-walled line 14 and remove the removal area 16 from the closing wall 10. Thus, as shown in FIG. 9, a discharge opening 76 is formed in the closing wall 10. Thereafter, by appropriately tilting the container, the contents of the container are discharged through the discharge opening 76.

[0024] After the discharge of the contents is completed, the upper lid 6 is pivoted around the hinge means 7 in the closing direction, that is, in the direction of covering the closing wall 10, to the closed position. At this time, in the container lid configured according to the present invention, when the upper lid 6 is pivoted in the closing direction with the elastic locking means 66 released from the locking recess 72, the elastic locking means 66 abuts against the locking lower surface 74 and the pivoting in the closing direction is inhibited, and the locked protrusion 62 formed on the upper lid 6 elastically overcomes and is locked to the auxiliary locking protrusion 68 formed on the locking wall 38 of the lid body 4. In other words, the locked protrusion 62 can overcome the auxiliary locking protrusion 68 but cannot overcome the locking protrusion 40. In the illustrated embodiment, since the pair of elastic locking pieces 66a and 66b extend upward and widen in the circumferential direction, as shown by the broken line in FIG. 10, the extending end portion of the elastic locking means 66 abuts against the locking lower surface 74 without being received in the locking recess 72, and the pivoting in the closing direction is inhibited. Thus, the upper lid 6 is held in the closed position. When the upper lid 6 is in the closed position, the outer surface of the lower end portion of the hanging wall 58 formed on the top wall 52 of the upper lid 6 is in close contact with the inner surface of the pouring guide inner wall 36 formed on the lid body 4.

[0025] Here, when the locked ridge 62 is locked with the auxiliary locking ridge 68, the top lid 6 floats slightly relative to the lid body 4 as shown in Figure 10, and this floating clearly indicates that the top lid 6 has been opened. In other words, in a container lid constructed according to the present invention, the elastic locking means 66 extending upward from the top surface of the locking wall 38 and the locking recess 72 provided on the inner surface of the skirt wall 54 constitute a tamper-evident mechanism, and because the tamper-evident mechanism is disposed inside the container lid, the tamper-evident mechanism will not be damaged when a large number of container lids are stored in a container or the like and transported. In the illustrated embodiment, since the central connecting piece 8 of the hinge means 7 has the required shape as described above, when the top cover 6 is held in the closed position again, as can be understood by comparing and referring to Figures 8 and 11, the lower surface of the thick-walled base end side portion 8a-1 of the upper connecting piece 8a and the upper surface of the thick-walled base end side portion 8b-1 of the lower connecting piece 8b face each other in the vertical direction, but the lower surface of the thin-walled connecting end side portion 8a-2 of the upper connecting piece 8a and the upper surface of the thin-walled connecting end side portion 8b-2 of the lower connecting piece 8b do not face each other, and the lower surface of the thin-walled connecting end side portion 8a-2 of the upper connecting piece 8a and the upper surface of the thin-walled connecting end side portion 8b-2 of the lower connecting piece 8b form a dogleg with their respective radially outer edge as inflection points, and the top cover 6 is displaced slightly upward relative to the cover body 4. As a result, the entire top cover 6 floats relative to the cover body 4, the top wall 52 becomes substantially horizontal, and the gap between the underside of the skirt wall 54 and the upper surface of the blocking wall 10 caused by the floating exists around the entire circumference.

[0026] As described above, the synthetic resin container lid configured according to the present invention has been described in detail with reference to the attached drawings. However, the present invention is not limited to the above-described embodiments, and appropriate modifications and changes can be made without departing from the scope of the present invention. For example, in the illustrated embodiment, the elastic locking means 66 is a pair of elastic locking pieces 66a and 66b arranged close to each other in the circumferential direction. Each of the pair of elastic locking pieces 66a and 66b extends upward from the upper surface of the locking wall 38 in a direction away from each other on the opposite side in the circumferential direction. However, each of the pair of elastic locking pieces may extend in a direction approaching each other upward. In this case, both ends of each of the pair of elastic locking pieces may be connected to each other. Further, each of the pair of elastic locking pieces may have a common base end on the upper surface of the locking wall or above it, and after separating from each other upward from such a base end, they approach each other again and are connected to each other at the upper ends. Furthermore, the elastic locking means does not necessarily have to be composed of a pair of elastic locking pieces. (1) It can be accommodated in the locking recess by using a required guiding jig. (2) When the upper lid is rotated in the opening direction from the closed position while being accommodated in the locking recess, it is released from the locking recess. (3) When the upper lid is rotated toward the closed position in a state of being released from the locking recess, the extended end portion abuts against the locking lower surface without being accommodated in the locking recess, and the upper lid is inhibited from rotating in the closing direction. As long as it is in such a form, it may be composed of a single elastic locking piece. Furthermore, the elastic locking piece may be linear.

Explanation of Reference Numerals

[0027] 2: Synthetic resin container lid 4: Lid body 6: Upper lid 8: Hinge means 10: Closing wall 12: Mounting wall 38: Locking wall 40: Locking ridge 62: Locked ridge 66: Elastic locking means 66a and 66b: Elastic locking pieces 68: Auxiliary locking ridge 70: Thick portion 72: Locking recess 74: Locking bottom surface

Claims

1. A container lid made of synthetic resin, comprising a lid body and an upper lid which is connected to the lid body via hinge means and is rotatable between a closed position covering the upper surface of the lid body and an open position exposing the upper surface of the lid body. The lid body includes a closing wall and a cylindrical mounting wall hanging down from the periphery of the closing wall. A cylindrical locking wall is disposed at the outer peripheral edge of the upper surface of the closing wall, and a locking ridge is formed on the outer peripheral surface of the locking wall. The upper lid includes a top wall and a cylindrical skirt wall hanging down from the periphery of the top wall. At the lower end of the inner peripheral surface of the skirt wall, a locked ridge is formed which is locked to the locking wall formed on the lid body when the upper lid is rotated to the closed position. Elastic locking means extending upward is disposed on the upper surface of the locking wall. Above the locked ridge on the inner surface of the skirt wall, a thick-walled portion with a reduced inner diameter of the skirt wall is provided. A locking recess with an open lower surface is formed on the inner surface of the thick-walled portion, and locking lower surfaces are defined on both circumferential sides of the locking recess. An auxiliary locking ridge is disposed at the upper end of the outer peripheral surface of the locking wall. When the tip of the elastic locking means is received in the locking recess and the upper lid is in the closed position as the initial state, in the initial state, the locked ridge is locked to the locking ridge. When the upper lid is rotated in the opening direction from the initial state toward the open position, the locked ridge elastically overrides the locking ridge and the auxiliary locking ridge, and the elastic locking means is released from the locking recess. After the elastic locking means is released from the locking recess and the upper lid is rotated in the closing direction toward the closed position, the elastic locking means is brought into contact with the locking lower surface, and the locked ridge is locked to the auxiliary locking ridge. The synthetic resin container lid is characterized by this.

2. The elastic locking means is a pair of elastic locking pieces arranged adjacent to each other in the circumferential direction, and each of the pair of elastic locking pieces extends upward and away from each other from the upper surface of the closing wall. The synthetic resin container lid according to Claim 1.

3. The elastic locking means is disposed on both diametrical sides extending perpendicular to a straight line connecting the circumferential center of the hinge means and the center of the closing wall in a plan view. The synthetic resin container lid according to Claim 1.

4. Both the locked ridge and the auxiliary locking ridge are in an annular shape extending continuously in the circumferential direction. The synthetic resin container lid according to Claim 1.

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