Synthetic resin container lid and its manufacturing method

Abstract

To provide a synthetic resin container lid and a manufacturing method thereof that prevent a locking piece 56 from buckling when a top lid 6 is rotated to a closed position to elastically engage the locking piece 56 to a locked piece 40.SOLUTION: The locking piece 56 is configured to include a flange portion 74 that extends radially outward below a breakable bridge portion 70 and can be pressed from above when the top lid 6 is rotated to a closed position.SELECTED DRAWING: Figure 9

Description

Technical Field

[0001] The present invention relates to a container lid including a lid body and an upper lid connected to the lid body via hinge means and pivotally connected to the lid body between a closed position covering the lid body and an open position exposing the lid body.

Background Art

[0002] As an example of a container lid including a lid body and an upper lid connected to the lid body via hinge means and pivotally connected to the lid body between a closed position covering the lid body and an open position exposing the lid body, Patent Document 1 below discloses that the lid body includes a closing wall and a cylindrical mounting wall hanging down from the periphery of the closing wall, an endless thin breakable line is formed in the closing wall, the upper lid includes a top wall and a skirt wall hanging down from the periphery of the top wall, a locking piece extending downward via a breakable bridging portion is disposed on the skirt wall, and a locked piece is disposed on the mounting wall. When the upper lid is pivoted to the closed position, the locking piece is elastically locked to the locked piece, and when the upper lid is pivoted from the closed position to the open position, the breakable bridging portion is broken and the locking piece is separated from the skirt wall, showing a synthetic resin container lid.

[0003] In the synthetic resin container lid shown in Patent Document 1, when the upper lid is pivoted from the closed position to the open position, the breakable bridging portion is broken, clearly indicating that the upper lid has been opened with respect to the lid body, thus ensuring the so-called tamper-evident property.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Since the synthetic resin container lid shown in the above Patent Document 1 is molded by a molding machine with the upper lid in the open position relative to the lid body, after the molded container lid is taken out of the molding machine, the upper lid is forcibly swiveled to the closed position relative to the lid body. In the final step where the upper lid is swiveled to the closed position, the upper lid is pressed downward by a bending machine, and the locking piece elastically overrides and locks to the locked piece. Resistance acts when the locking piece overrides the locked piece. Here, in the synthetic resin container lid shown in the above Patent Document 1, since the locking piece extends downward from the lower end of the skirt wall and is entirely displaced radially inward from the outer peripheral surface of the skirt wall, only the top wall is pressed downward by the bending machine. Therefore, in the synthetic resin container lid shown in the above Patent Document 1, the pressing force applied to the top wall concentrates on the locking piece, and the locking piece may buckle with the breakable bridging portion as the base end.

[0006] The present invention has been made in view of the above facts, and its main technical problem is to provide a novel and improved synthetic resin container lid and a manufacturing method thereof in which buckling of the locking piece is prevented when the upper lid is swiveled to the closed position and the locking piece is elastically locked to the locked piece.

Means for Solving the Problems

[0007] As a result of intensive studies, the present inventors have found that the main technical problem can be solved by providing a flange portion that extends radially outward below the breakable bridging portion and can be pressed from above when the upper lid is swiveled to the closed position.

[0008] That is, according to the first aspect of the present invention, as a synthetic resin container lid that solves the above main technical problem, it includes a lid body, and an upper lid that is connected to the lid body via hinge means and is rotatably connected to the lid body between a closed position that covers the upper surface of the lid body and an open position that exposes the upper surface of the lid body. The lid body includes a closing wall and a cylindrical mounting wall that hangs down from the periphery of the closing wall, and the upper lid includes a top wall and a skirt wall that hangs down from the periphery of the top wall. The skirt wall is provided with a locking piece that extends downward via a breakable bridging portion, and the mounting wall is provided with a locked piece. When the upper lid is pivoted to the closed position, the locking piece is elastically locked to the locked piece. When the upper lid is pivoted from the closed position to the open position, the breakable bridging portion is broken and the locking piece is separated from the skirt wall. In a synthetic resin container lid, The locking piece is provided with a flange portion that extends radially outward below the breakable bridging portion and can be pressed from above when the upper lid is pivoted to the closed position. A synthetic resin container lid characterized by this is provided.

[0009] Preferably, the radially outer end of the flange portion is located radially outside the outer peripheral surface of the skirt wall. A protruding portion protruding radially outward is provided on the outer peripheral surface of the skirt wall, and the breakable bridging portion is preferably provided on the lower surface of the protruding portion. In this case, before the upper lid is pivoted to the closed position and the breakable bridging portion is broken, the breakable bridging portion is preferably at the same height as or slightly below the lower end position of the skirt wall in the vertical direction. Preferably, a protrusion having a locking upper surface extending radially outward is provided at the lower end portion of the locking piece, and a belt-shaped main portion spaced radially outward from the outer peripheral surface of the mounting wall and extending circumferentially along the outer peripheral surface is provided on the piece to be locked. When the upper lid is pivoted to the closed position, the protrusion of the locking piece passes between the main portion of the piece to be locked and the mounting wall. When the upper lid is pivoted from the closed position toward the open position, the locking upper surface of the protrusion is locked to the lower surface of the main portion of the piece to be locked. In this case, the protrusion preferably has an inclined lower surface that extends radially inwardly downward from the radially outer end of the locking upper surface, and the circumferential width of the protrusion preferably gradually decreases downward. After the breakable bridging portion is broken, the lower surface of the flange portion of the locking piece is preferably locked to the upper surface of the main portion of the piece to be locked. The locking piece and the piece to be locked are preferably provided on both sides in the diametrical direction perpendicular to the diameter passing through the circumferential center angle position of the hinge means in plan view. Preferably, a removal area is defined on the closing wall by an endless thin-wall breakable line, a connecting column extending upward is disposed on the upper surface of the removal area, and a tension ring is connected to the upper end of the connecting column.

[0010] According to a second aspect of the present invention, as a method for manufacturing a synthetic resin container lid that solves the above main technical problem, when pivoting the upper lid to the closed position, a manufacturing method is provided in which the flange portion of the locking piece is pressed downward together with the top wall.

[0011] In the manufacturing method according to the second aspect of the present invention, when a protruding portion protruding radially outward is provided on the outer peripheral surface of the skirt wall and the breakable bridging portion is connected to the lower surface of the protruding portion, when turning the upper lid to the closed position, it is preferable to press the upper end surface of the protruding portion downward as well.

Advantages of the Invention

[0012] In the synthetic resin container lid of the present invention, the locking piece is provided with a flange portion extending radially outward below the breakable bridging portion. When turning the upper lid to the closed position to elastically lock the locking piece to the locked piece, the flange portion provided on the locking piece can be pressed downward together with the top wall. As a result, the posture of the locking piece is maintained, and the locking piece is elastically locked to the locked piece without buckling.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7-1

Figure 7-2

Figure 7-3

Figure 8

Figure 9

Figure 10

Embodiments for Carrying Out the Invention

[0014] 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 in which 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.

[0015] Referring to Figs. 1 to 6, 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 8.

[0016] Referring mainly to FIGS. 1 and 4, the lid body 4 includes a circular closing wall 10 in plan view and a cylindrical mounting wall 12 hanging down from the periphery of the closing wall 10. As shown in FIG. 4, the closing wall 10 is partitioned into a mortar-shaped central portion 14 recessed downward and a substantially annular outer peripheral portion 16 surrounding the central portion 14. The central portion 14 is somewhat displaced diametrically opposite to the hinge means 8 with respect to the axial center of the closing wall 10. A removal area 20 is defined in the central portion 14 of the closing wall 10 by an endless thin breakable line 18. The endless thin breakable line 18 is composed of a so-called score formed by locally reducing the thickness of the closing wall 10. On the upper surface of the removal area 20, a connecting column 22 extending upward is disposed, and a tension ring 24 is connected to the upper end of the connecting column 22. A cylindrical pouring guide wall 26 extending upward is formed at the boundary between the central portion 14 and the outer peripheral portion 16 from the upper surface of the closing wall 10. The extending end portion, that is, the upper end portion of the pouring guide wall 26 has a lip shape curved radially outward. On the upper surface of the outer peripheral portion 16, more specifically, on the outer peripheral edge portion of the upper surface of the closing wall 10, a cylindrical engaging wall 28 extending radially outward upward is provided, and an engaging ridge 30 protruding radially outward is formed at the upper end portion of the outer peripheral surface of the engaging wall 28. On the lower surface of the outer peripheral portion 16, a cylindrical seal wall 32 hanging downward is formed.

[0017] Locking means 34 is disposed at the lower end of the inner circumferential surface of the mounting wall 12. In the illustrated embodiment, as shown in FIG. 2, the locking means 34 is composed of a plurality of (six in the illustrated embodiment) arcuate ridges extending in the circumferential direction with an interval in the circumferential direction. If desired, the locking means can also be composed of an annular ridge extending continuously in the circumferential direction. As can be understood by referring to FIG. 5 together with FIGS. 1 and 4, in a required angular region located diametrically opposite to the hinge means 8 on the mounting wall 12, a notch 36 extending in an arc shape is formed at the upper part of the mounting wall 12, and a shallow recess 38 extending in an arc shape is formed on the outer circumferential surface of the mounting wall 12 below such a notch 36. A locked piece 40 is further disposed at a required part of the outer circumferential surface of the mounting wall 12. The locked piece 40 will be described later. As shown in FIG. 1, the mounting wall 12 is further provided with a known separation mechanism including a bottomed annular groove 42 with an open upper surface and an axial slit 44 (see also FIGS. 3 and 4). After the container lid 2 is mounted on the mouth-neck part of the container described later and used, by performing a required operation, the container lid 2 can be separated from the mouth-neck part and discarded. For details of such a separation mechanism, for example, refer to Japanese Patent No. 6326472, which was previously filed by the applicant of the present application and has already been patented.

[0018] Continuing the description mainly with reference to FIGS. 1 and 4, the upper lid 6 includes a circular top wall 46 and a cylindrical skirt wall 48 that hangs down from the periphery of the top wall 46. The lower end of the outer peripheral surface of the skirt wall 48 is connected to the upper end of the outer peripheral surface of the mounting wall 12 of the lid body 4 via hinge means 8, and the upper lid 6 is rotatable between a closed position covering the upper surface of the closing wall 10 of the lid body 4 and an open position exposing the upper surface of the closing wall 10 of the lid body 4. An inner cylindrical wall 50 and an outer cylindrical wall 52 that hang downward are also formed on the lower surface of the top wall 46, and two annular shallow grooves 54 are formed between the inner cylindrical wall 50 and the outer cylindrical wall 52. As shown in FIG. 3, a locking piece 56 is disposed at a required portion of the lower end of the outer peripheral surface of the skirt wall 48. The locking piece 56 will be described later together with the locked piece 40. As can be understood by referring to FIG. 6 together with FIGS. 1 and 4, a flange portion 58 that protrudes radially outward is disposed at a portion diametrically opposite to the hinge means 8 at the lower end of the outer peripheral surface of the skirt wall 48, and a finger can be hooked on the flange portion 58 when the upper lid 6 is rotated to open and close. A thin-walled arc-shaped protruding piece 60 that protrudes downward is formed at a portion diametrically opposite to the hinge means 8 when viewed in the diameter direction on the lower surface of the skirt wall 48. An annular engaged protrusion 62 is disposed at the lower end of the inner peripheral surface of the skirt wall 48, and an annular abutting protrusion 64 that is located above the annular engaged protrusion 62 is also disposed on the inner peripheral surface of the skirt wall 48.

[0019] Next, with reference mainly to FIGS. 1, 3, 5, and 6, the locked piece 40 disposed on the lid body 4 and the locking piece 56 disposed on the upper lid 6 will be described. In the illustrated embodiment, the locking piece 56 and the locked piece 40 are each provided one on each side in the diametrical direction perpendicular to the diameter passing through the circumferential center angle position of the hinge means 8 in a plan view (that is, FIG. 1). As can be understood by referring to FIGS. 1, 3, and 5, the locked piece 40 has a belt-shaped main portion 66 that extends substantially horizontally in the circumferential direction along the outer peripheral surface of the mounting wall 12 while being radially separated from the outer peripheral surface of the mounting wall 12, and a pair of connecting portions 68 that connect the inner peripheral surface of the belt-shaped main portion 66 and the outer peripheral surface of the mounting wall 12 at both circumferential ends of the belt-shaped main portion 66, and has a U-shaped shape facing downward in a side view, that is, FIG. 3. For example, as shown in FIG. 7-1, the upper end portion of the inner peripheral surface of the belt-shaped main portion 66 is an annular tapered surface that slopes radially inward downward. On the other hand, as can be understood by referring to FIGS. 1, 3, and 6, the locking piece 56 is disposed on the skirt wall 48 via a breakable bridging portion 70 and extends downward beyond the lower end of the skirt wall 48. In the illustrated embodiment, a protruding portion 72 that protrudes radially outward is provided on the outer peripheral surface of the skirt wall 48, and the breakable bridging portion 70 is provided on the lower surface of the protruding portion 72. Here, in the present invention, it is important that the locking piece 56 includes a flange portion 74 that extends radially outward below the breakable bridging portion 70. As shown in FIGS. 3 and 6, in the illustrated embodiment, the flange portion 74 extends substantially horizontally radially outward immediately below the breakable bridging portion 70, and the radially outer end of the flange portion 74 is located radially outward of the outer peripheral surface of the protruding portion 72 (and thus radially outward of the outer peripheral surface of the skirt wall 48). A protrusion 76 that protrudes radially outward is formed at the lower end portion of the locking piece 56. The protrusion 76 includes a locking upper surface 78 that extends substantially horizontally radially outward and an inclined lower surface 80 that extends radially inward and downward from the radially outer end of the locking upper surface 78, and the circumferential width of the protrusion 76 gradually decreases downward. The locking upper surface 78 of the protrusion 76 and the lower surface of the flange portion 74 are positioned at a required interval in the vertical direction.

[0020] The above-mentioned container lid 2 is formed by a molding machine with the upper lid 6 in the open position relative to the lid body 4. After the formed container lid 2 is taken out of the molding machine, the upper lid 6 is forcibly rotated to the closed position relative to the lid body 4. In the final step where the upper lid 6 is rotated to the closed position, the upper lid 6 is pressed downward by a bending machine, and the locking piece 56 elastically overrides and locks to the locked piece 40. FIGS. 7-1 to 7-3 show the step of pressing the upper lid 6 downward by a bending machine indicated by the reference numeral 82 as a whole. The bending machine 82 includes a support portion 84 that supports the lid body 4 of the container lid 2 from below and a pressing portion 86 that presses the upper lid 6 of the container lid 2 downward. The pressing portion 86 further has a central pressing main portion 88 and pressing auxiliary portions 90 arranged on both sides in the diametrical direction of the pressing main portion 88. The pressing main portion 88 and the pressing auxiliary portions 90 are integrally movable in the vertical direction. As shown in FIG. 7-1, the lower surface 88a of the pressing main portion 88 is flat and presses the upper surface of the top wall 46 downward. On the other hand, the lower surface of the pressing auxiliary portion 90 has two flat surfaces with different vertical positions. The inner lower surface 90a located radially inside and relatively above presses the upper surface of the protrusion 72 provided on the skirt wall 48, and the outer lower surface 90b located radially outside and relatively below presses the upper surface of the flange portion 74 provided on the locking piece 56 downward at the same time.

[0021] FIG. 7-1 shows a state in which the lower end of the locking piece 56 provided on the upper lid 6 is separated upward from the locked piece 40 provided on the lid body 4. When the pressing portion 86 descends from the state shown in FIG. 7-1, the upper lid 6 of the container lid 2 is thereby pivoted and closed with respect to the lid body 4. As shown in FIG. 7-2, the locking piece 56 provided on the upper lid 6 abuts against the locked piece 40 provided on the lid body 4. In the illustrated embodiment, the upper end portion of the inner peripheral surface of the strip-shaped main portion 66 of the locked piece 40 is an annular tapered surface that slopes radially inward downward, and the protrusion 76 formed at the lower end portion of the locking piece 56 has an inclined lower surface 80 that slopes radially inward downward. Therefore, the protrusion 76 formed at the lower end portion of the locking piece 56 is smoothly guided between the inner peripheral surface of the strip-shaped main portion 66 of the locked piece 40 and the outer peripheral surface of the mounting wall 12. When the pressing portion 86 further descends from the state shown in FIG. 7-2, in the locking piece 56, the entire body is displaced radially inward with the breakable bridging portion 70 as the base end, and in the locked piece 40, the strip-shaped main portion 66 thereof is displaced radially outward. The protrusion 76 elastically overrides the strip-shaped main portion 66, and thus, as shown in FIG. 7-3, the locking piece 56 is elastically locked to the locked piece 40 (see also FIG. 8). In the state where the locking piece 56 is locked to the locked piece 40, there is a somewhat vertical gap between the lower surface of the flange portion 74 of the locking piece 56 and the upper surface of the strip-shaped main portion 66 of the locked piece 40. Further, in the state where the locking piece 56 is locked to the locked piece 40, the breakable bridging portion 70 is preferably at the same height as or slightly below the lower end position of the skirt wall 48 in the vertical direction.

[0022] Here, in the synthetic resin container lid of the present invention, the locking piece 56 includes a flange portion 74 that extends radially outward below the breakable bridging portion 70. When the upper lid 6 is pivoted to the closed position to elastically override the locked piece 40 with the locking piece 56, although a required resistance is generated, together with the top wall 46, the flange portion 74 provided on the locking piece 56 can also be pressed downward. As a result, the posture of the locking piece 56 is maintained, and the locking piece 56 is elastically locked to the locked piece 40 without buckling.

[0023] When the upper lid 6 is pivoted to the closed position, as shown in FIG. 7-3, the annular engaged protrusion 62 of the upper lid 6 is engaged with the outer peripheral surface or the lower surface of the engaging protrusion 30 of the lid body 4, the annular abutting protrusion 64 of the upper lid 6 is abutted against the upper end of the engaging wall 28 of the lid body 4, the outer peripheral surface of the inner cylindrical wall 50 of the upper lid 6 is closely attached to the inner peripheral surface of the pouring guide inner wall 26 of the lid body 4, and as shown in FIGS. 8 and 9, the thin-walled arcuate protruding piece 60 of the upper lid 6 is positioned in the notch 36 of the lid body 4.

[0024] In FIG. 4, the neck portion of the container to which such a container lid 2 is applied together with the container lid 2 configured according to the present invention is also shown by a two-dot chain line. The 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 locked protrusion 102 is formed at the upper end of its outer peripheral surface. On the outer peripheral surface of the neck portion 100, a support ring 104 (which is used when transporting the container) is also formed below the locked protrusion 102. Although it is actually impossible for the container lid 2 to be attached to the neck portion 100 of the container in the state shown in FIG. 4, that is, when the upper lid 6 is in the open position and before the locking piece 56 and the locked piece 40 are locked, the neck portion 100 of the container is shown in FIG. 4 for convenience of explanation.

[0025] When the container lid 2 is attached to the neck portion 100 to seal the neck portion 100 after the container is filled with the contents, the container lid 2, more specifically, the container lid 2 with the upper lid 6 in the closed position with respect to the lid body 4, is fitted onto the neck portion 100 and forced downward, elastically deforming the mounting wall 12 of the lid body 4 so that the locking means 34 formed on the inner peripheral surface of the mounting wall 12 is locked below the locked protrusion 102 of the neck portion 100.

[0026] When consuming the contents of the container, place a finger on the lower surface of the flange portion 58 of the upper lid 6 and apply an upward force to the flange portion 58 with the hinge means 8 as the center of rotation. Due to such an upward force, the upper lid 6 tries to rotate, that is, rotate and open in the direction from the closed position to the open position. However, such rotation and opening are restricted as long as the locking piece 56 provided on the upper lid 6 and the locked piece 40 provided on the lid body 4 are locked. More specifically, the upper surface 78 of the protrusion 76 provided on the locking piece 56 and the lower surface of the belt-shaped main portion 66 of the locked piece 40 are locked. Since the above upward force tries to apply a vertical tensile force to the breakable bridging portion 70 connecting the locking piece 56 and the protrusion 72 of the skirt wall 48 to break it, the rotational opening and closing movement of the upper lid 6 is allowed after the breakable bridging portion 70 is broken by the above upward force. After the breakable bridging portion 70 is broken, the locking piece 56 freely falls, and then, as shown in FIG. 10, the lower surface of the flange portion 74 is locked to the upper surface of the belt-shaped main portion 66 of the locked piece 40. That is, the locking piece 56 is allowed to freely fall by the above-mentioned some interval existing between the lower surface of the flange portion 74 and the upper surface of the belt-shaped main portion 66 of the locked piece 40. Since the breakage of the breakable bridging portion 70 clearly indicates that the upper lid has been opened with respect to the lid body, the so-called tamper-evident characteristic is ensured. In the illustrated embodiment, even after the breakable bridging portion 70 is broken, the locking piece 56 is such that the lower surface of the flange portion 74 is locked to the upper surface of the belt-shaped main portion 66 of the locked piece 40, and the upper locking surface 78 of the protrusion 76 is locked to the lower surface of the belt-shaped main portion 66 of the locked piece 40. Therefore, the locking piece 56 is not separated from the container lid 2 and is continuously held thereon, so the locking piece 56 itself does not become waste.

[0027] After the breakable bridging portion 70 has been broken, the upper lid 6 is pivoted and opened from the closed position to the open position, and the upper surface of the closing wall 10 of the lid body 4 is exposed. Then, a finger is hooked on the tension ring 24 of the lid body 4 and forced upward to break the endless thin-walled breakable line 18 to remove the removal region 20 from the closing wall 10, thereby generating a discharge opening. After that, by appropriately tilting the container, the contents of the container are discharged through the discharge opening. After the discharge of the contents is completed, the upper lid 6 is pivoted and closed toward the closed position and reattached to the lid body 4. When the upper lid 6 is in a state of being reattached to the lid body 4, since the breakable bridging portion 70 has already been broken and its broken end faces are axially spaced apart, the so-called tamper-evident characteristic is improved thereby.

[0028] The synthetic resin container lid of the present invention has been described in detail with reference to the attached drawings above. However, the present invention is not limited to the above-described embodiments, and various modifications can be considered without departing from the scope of the present invention. For example, in the illustrated embodiment, the radially outer end of the flange portion 74 was located radially outside the outer peripheral surface of the skirt wall 48. However, by providing a groove penetrating vertically in a required portion of the outer peripheral surface of the skirt wall and providing the flange portion in such a groove, the radially outer end of the flange portion can be located radially inside the outer peripheral surface of the skirt wall. Further, in the illustrated embodiment, a protruding portion 72 protruding radially outward is provided on the outer peripheral surface of the skirt wall 48, and the breakable bridging portion 70 is provided on the lower surface of the protruding portion 72. However, the breakable bridging portion 70 may be provided on the lower surface of the skirt wall and the protruding portion 72 may be omitted. In this case, the bending machine presses only the flange portion downward without pressing the upper end surface of the protruding portion. In the illustrated embodiment, the protrusion 76 of the locking piece 56 and the belt-shaped main portion 66 of the locked piece 40 are elastically displaced radially with respect to each other, and the protrusion 76 of the locking piece 56 overrides the belt-shaped main portion 66 of the locked piece 40, so that the locking piece 56 is locked to the locked piece 40. Instead of providing the protrusion 76 on the locking piece 56, for example, hook portions that hang downward from the lower surface of the flange portion 74 and then extend upward toward both circumferential sides may be provided, and such hook portions may be locked to the lower surface of each of a pair of connecting portions 68 provided on the locked piece 40. Furthermore, in the illustrated embodiment, the endless thin-walled breakable line 18 is broken by the tension ring 24 to generate a discharge opening in the closing wall 10. However, the method of generating a discharge opening in the closing wall may be an appropriate method without relying on the tension ring. For example, as shown in Japanese Patent Application No. 2021-137189 filed by the applicant prior to the present application, the closing wall of the lid body and the top wall of the upper lid are connected by appropriate connecting means, and the endless thin-walled breakable line is broken simultaneously when the upper lid pivots and opens from the closed position.

Explanation of Reference Numerals

[0029] 2: Container lid 4: Lid body 6: Upper lid 8: Hinge means 10: Blocking wall 12: Mounting wall 40: Locked piece 46: Top wall 48: Skirt wall 56: Locking piece 70: Breakable bridging part 74: Flange part

Claims

1. A container lid made of synthetic resin, comprising a lid body and an upper lid connected to the lid body via hinge means and rotatably connected to the lid body 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, and the upper lid includes a top wall and a skirt wall hanging down from the periphery of the top wall. A locking piece extending downward via a breakable bridging portion is disposed on the skirt wall, and a locked piece is disposed on the mounting wall. When the upper lid is rotated to the closed position, the locking piece is elastically locked to the locked piece. When the upper lid is rotated from the closed position to the open position, the breakable bridging portion is broken and the locking piece is separated from the skirt wall. The locking piece is provided with a flange portion extending radially outward below the breakable bridging portion and capable of being pressed from above when the upper lid is rotated to the closed position. The synthetic resin container lid is characterized by this.

2. The synthetic resin container lid according to Claim 1, wherein the radially outer end of the flange portion is located radially outside the outer peripheral surface of the skirt wall.

3. The synthetic resin container lid according to Claim 1 or 2, wherein a protruding portion protruding radially outward is provided on the outer peripheral surface of the skirt wall, and the breakable bridging portion is provided on the lower surface of the protruding portion.

4. The synthetic resin container lid according to Claim 3, wherein, in a state before the upper lid is rotated to the closed position and the breakable bridging portion is broken, the breakable bridging portion is at the same height as or slightly below the lower end position of the skirt wall in the vertical direction.

5. A protrusion having a locking upper surface extending radially outward is provided at the lower end portion of the locking piece, and a belt-shaped main portion spaced radially outward from the outer peripheral surface of the mounting wall and extending circumferentially along the outer peripheral surface is provided on the locked piece. When the upper lid is rotated to the closed position, the protrusion of the locking piece passes between the main portion of the locked piece and the mounting wall. When the upper lid is rotated from the closed position toward the open position, the locking upper surface of the protrusion is locked to the lower surface of the main portion of the locked piece. The synthetic resin container lid according to any one of Claims 1 to 4.

6. The synthetic resin container lid according to Claim 5, wherein the protrusion is provided with an inclined lower surface inclined radially inward downward from the radially outer end of the locking upper surface.

7. The circumferential width of the protrusion gradually decreases downward, the synthetic resin container lid according to claim 5 or 6.

8. After the breakable bridging portion is broken, the lower surface of the flange portion of the locking piece is locked to the upper surface of the main portion of the locked piece, the synthetic resin container lid according to any one of claims 5 to 7.

9. The locking piece and the locked piece are respectively provided on both sides in the diametrical direction perpendicular to the diameter passing through the circumferential center angular position of the hinge means in a plan view, the synthetic resin container lid according to any one of claims 1 to 8.

10. An area to be removed is defined on the closing wall by an endless thin breakable line, a connecting column extending upward is disposed on the upper surface of the area to be removed, and a tension ring is connected to the upper end of the connecting column, the synthetic resin container lid according to any one of claims 1 to 9.

11. In a method of manufacturing a synthetic resin container lid according to any one of claims 1 to 10, When the upper lid is turned to the closed position, the flange portion of the locking piece is pressed downward together with the top wall, the manufacturing method.

12. In a method of manufacturing a synthetic resin container lid that cites claim 3 in claim 11, when the upper lid is turned to the closed position, the upper end surface of the protrusion is also pressed downward, the manufacturing method.

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