JPS62251351A - Vessel cover made of synthetic resin having pilfer-proof characteristic - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a synthetic resin container lid having pilfer-proof properties.

<Prior Art> Recently, as container lids applied to the mouth and neck of containers for drinks etc., for example, Japanese Patent Publication No. 58-32105, Japanese Patent Application Laid-Open No. 57-153862, Japanese Patent Publication No. 59-1982
Publication No. 52100, Special Publication No. 57-500972,
JP-A-58-30949 and JP-A-61-473
As disclosed in Japanese Patent No. 51, a circular top wall, a cylindrical skirt wall that hangs down from the periphery of the top wall, and a plurality of bridges disposed at intervals in the circumferential direction are used to connect the skirt to the top wall. The left side of the pilfer-proof hem wall is connected to the lower end of the wall, and the inner peripheral surface of the pilfer-proof hem wall is formed with locking protrusions of various shapes that protrude radially inward. , synthetic resin container lids with pilfer-proof properties have been proposed and are beginning to be put into practical use. In many cases, an internal thread is formed on the inner peripheral surface of the skirt wall.

<Problem to be solved> The conventional container lid of the above type has the following problem to be solved.

Container lids of the above type are molded by injection molding or compression molding, but because of the presence of so-called undercuts in various parts of the container lid, the molded container lid cannot be used unless an extremely complicated mold is used. When removing the mold from the mold, it is necessary to perform so-called forced punching. However, when carrying out forced extraction, the undercuts that exist between the skirt wall and the pilfer-proof hem wall and/or the undercuts caused by the locking protrusions formed on the inner circumferential surface of the pilfer-proof hem wall. As a result, excessive stress is generated in the plurality of bridges connecting the pilfer-proof hem wall to the skirt wall, and there is a considerable risk that the bridge will fail due to this. Moreover, by performing forced punching, the locking protrusions and/or female threads are considerably deformed from the desired shape during molding.

On the other hand, in the above-mentioned Japanese Patent Application Laid-Open No. 57-153862, in order to prevent an undercut from being generated between the skirt wall and the pilfer-proof hem wall, the inner diameter of the upper end of the pilfer-proof hem wall is changed to the lower end of the skirt wall. It is disclosed that the outer diameter is the same as or slightly larger than the outer diameter. However, in addition to the fact that the undercut caused by the locking protrusion formed on the inner peripheral surface of the pilfer-proof hem wall remains, as mentioned above, the inner diameter of the upper end of the pilfer-proof hem wall is connected to the lower end of the skirt wall. If the outside diameter is made equal to or slightly larger than the outside diameter, a separate problem arises as follows.

That is, when the container lid of the above type is attached to the mouth and neck of the container, the locking protrusion formed on the pilfer-proof hem wall and/or its inner peripheral surface is elastically displaced radially outward. Therefore, it is necessary for the locking protrusion to get over the locking jaw formed on the outer peripheral surface of the mouth and neck of the container. However, when the locking protrusion passes over the locking jaw, a considerable resistance force acts on the pilfur-proof hem wall against the downward movement of the pilfer-proof hem wall, which causes the pilfer-proof hem wall to move toward the skirt. The inner diameter of the upper end of the pilfer-proof hem is the same as or slightly larger than the outer diameter of the lower end of the skirt wall. Further rising of the proof skirt wall is not prevented, thus resulting in a significant rise of the pilfer proof skirt wall with respect to the skirt wall. Due to this, excessive stress is generated in the plurality of bridges connecting the pilfer-proof hem wall to the skirt wall, and there is a considerable possibility that the bridges will be broken.

In order to prevent the bridge from breaking when removed from the mold and/or when attached to the neck and neck of the container, it is intended to increase the strength of the bridge. It is necessary that the bridge portion be reliably and easily broken when the package is opened, and therefore it is not desirable to increase the strength of the bridge portion.

<Object of the Invention> The present invention has been made in view of the above-mentioned facts, and its main purpose is to be able to perform molding without requiring an extremely complicated molding die, substantially avoiding forced punching, and to To provide a synthetic resin container lid having a new and excellent pilfer-proof property, which reliably prevents the bridge from breaking when removed from the mold as well as from breaking when attached to the mouth and neck of the container. It is to be.

No locking protrusions are present on the inner circumferential surface of the pilfur-proof hem wall at specific portions facing each other in the diametrical direction, and locking protrusions are present on the inner circumferential surface of the pilfer-proof hem wall at locations other than the above-mentioned specific portions. , and also (El) in the above specific part, the upper end inner diameter d1 of the pilfer-proof hem wall
d1≧D with respect to the lower end outer shape of the skirt wall,
The above purpose can be achieved by adopting a unique configuration in which the inner diameter dt of the upper end of the pilfer-proof skirt wall is made to be [ ) > d with respect to the outer diameter of the lower end of the skirt wall at least in a part other than the above-mentioned specific parts. I found out what can be achieved.

That is, according to the present invention, a circular top wall, a cylindrical skirt wall that hangs down from the periphery of the top wall, and a plurality of bridges disposed at intervals in the circumferential direction of the skirt wall are connected to each other. Features an annular pilfer-proof hem wall connected to the bottom edge;
In a synthetic resin container lid having pilfer-proof properties, in which a locking projection protruding radially inward is formed on the inner circumferential surface of the pilfer-proof hem wall; The locking protrusion is not present on the inner circumferential surface of the pilfer-proof hem wall, and the locking protrusion is present on the inner circumferential surface of the pilfer-proof hem wall in areas other than the specific area, and the pill is not present in the specific area. The inner diameter d of the upper end of the fur-proof hem wall is d1≧D with respect to the outer diameter of the lower end of the skirt wall, and the inner diameter d of the upper end of the fur-proof hem wall is d1≧D in at least a part other than the specific part.
There is provided a container lid characterized in that 2 is [)>d with respect to the diameter of the lower end of the skirt wall.

In a preferred embodiment of the present invention, the two specific portions are located diametrically opposite each other, and d and −D are 1.0 mm.
D−d is equal to or greater than 0.7+u+, and a female thread interrupted at the specific portion is formed on the inner circumferential surface of the skirt wall.

<Preferred specific examples of the invention> A more detailed explanation will be given below with reference to the accompanying drawings.

Referring to FIG. 1, which illustrates one embodiment of a container lid constructed in accordance with the present invention, the container lid, designated generally by the numeral 2, may be made of a suitable material such as polypropylene or polyethylene. molded from a synthetic resin material by injection molding, compression molding, etc. (Such molding will be further referred to later.)
The illustrated container lid 2 includes a circular top wall 4, a cylindrical skirt wall 6 depending from the periphery of the top wall 4, and an annular pilfer-proof skirt wall 8 disposed below the skirt wall 6. The lower end of the skirt wall 6 and the building proof hem wall 8
A plurality of thin-walled bridging portions 10 (see FIGS. 2 and 3) are formed at intervals in the circumferential direction between the upper end and the pilfer-proof hem. The wall 8 is connected to the skirt wall 6 by a bridge 10. The outer peripheral surface of the skirt wall 6 is provided with a large number of projections and depressions 12 for preventing slippage. The upper part of the outer peripheral surface of the pilfer-proof hem wall 8 is inclined upwardly and somewhat inwardly.

Referring to FIG. 2 together with FIG. 1, the shapes of the inner circumferential surface of the skirt wall 6 and the inner circumferential surface of the pilfer-proof hem wall 8 are different between the two specific parts 12 and other parts. It is important that 2 specific parts 1
2 are preferably positioned diametrically opposite each other. The circumferential width of each of the two specific parts 12 may be uniform in the vertical direction, but gradually decreases upward, and therefore, each of the two specific parts 12 has a second
Preferably, it is trapezoidal in the developed view shown in the figure. A female thread 14 is formed on the inner circumferential surface of the skirt wall 6 at a portion other than the two specific portions 12 described above. In the two specific parts 12, the female thread 14 is not present.

In other words, the female thread 14 formed on the inner circumferential surface of the skirt wall 6 is interrupted at the two specific portions 12 .

The inner circumferential surface of the pilfer-proof hem wall 8 will be explained with reference to FIGS. d, and other than the two specific parts 12, the upper part of the pilfer-proof hem wall 8 has a relatively small inner diameter d2 (the lower part of the pilfer-proof hem wall 8 has a relatively large inner diameter d1). ), the outer diameter of the pilfer-proof hem wall 8 is the same in the two specific parts 12 and other parts, and therefore the wall thickness of the pilfer-proof hem wall 8 is the same as that in the two specific parts 12 and other parts. It is relatively thin in the upper portion of the portion other than the two specific portions 12, and relatively thick in the upper portion of the portion other than the two specific portions 12. As clearly shown in FIG. 4, it is important that the inner diameter d of the pilfer-proof skirt wall 8 at the two specific parts 12 satisfies d, ≧D with respect to the outer diameter of the lower end of the skirt wall 6. and d, -
It is desirable that D≦1.0 mm. On the other hand, as clearly shown in FIG. 5, the inner diameter d2 of the upper part of the pilfer-proof skirt wall 8 at a portion other than the two specific portions 12 is d2<[ with respect to the outer diameter of the lower end of the skirt wall 6. ) is important, and it is desirable that D-d2≧0.7 mm.

In the illustrated example, the inner diameter of the upper part of the pilfer-proof hem wall 8 is uniform over the entire region other than the two specific regions 12, and the above requirements (i.e., d2<
D and D-d, 20.7 mm), but if desired, the upper part of the pilfer-proof hem wall 8 may be partially adjusted to the inner diameter in a part other than the two specific parts 12. d2 (in this case, the part other than the part having the inner diameter d2 may have the same inner diameter as the inner diameter d1 in the specific portion 12). In this case, the lower part of the pilfer-proof hem wall 8 has a relatively large inner diameter in the parts other than the specific part 12, but the inner diameter of the lower part may also be set to d2 like the upper part. Furthermore, if desired, at the two specific locations 12 or at the two specific locations 12,
In a region other than the specific region 12, the inner peripheral surface of the pilfer-proof hem wall 8 can be inclined downwardly and outward in the radial direction, so that the inner diameter can be gradually increased downwardly. In this case, the inner diameters d1 and d2 of the upper end of the pilfer-proof skirt wall 8 are made to satisfy the above requirements.

As clearly shown in FIGS. 3 and 5, in areas other than the two specific areas 12, the inner circumferential surface of the pilfer-proof hem wall 8 has locking protrusions that protrude radially inward. 16 are formed. The illustrated locking protrusion 16 is similar to the above-mentioned 2
Although the locking protrusions extend continuously in the circumferential direction at a portion other than the specific portion 12, if desired, a plurality of locking protrusions may be formed at intervals in the circumferential direction. In the two specific portions 12, it is important that no locking protrusions are formed on the inner peripheral surface of the pilfer-proof hem wall z8. As understood by referring to FIGS. 2 and 3, the plurality of bridging parts 10 are not present in the two specific parts 12, but are
It is convenient that it is placed in a different location.

In the illustrated capacity 2':tM2, as shown in FIG.
8 are arranged. The sealing liner 18, which may be made of any suitable synthetic resin material, may be molded separately from the container lid body and inserted into position, or it may be stamped directly onto the inner surface of the top wall 4.

The container lid 2 as described above is applied to a container having a neck 20 which is known per se and illustrated in FIG. The neck 20 of the container, which can be formed from glass or a suitable synthetic resin material, is generally cylindrical and open at the top. A male thread 22 and an annular locking jaw 24 located below the male thread 22 are formed on the outer peripheral surface of the mouth portion 20 .

When attaching the container JhM2 to the mouth and neck part 20 and sealing the mouth and neck part 20, the container lid 2 is fitted onto the mouth part 20, and the sixth
Rotate the container lid 2 clockwise when viewed from above in the figure. In this way, the female thread 14 of the container lid 2 is connected to the neck part 20.
The container lid 2 is screwed into the male thread 22 of the container lid 2, so that the container lid 2 is lowered as it rotates.

As can be easily understood by referring to FIG.
When the container lid 2 is lowered, the pilfer-proof hem wall 8
The locking protrusion 16 formed on the inner peripheral surface of the mouth and neck part 20
is interfered with by the annular locking jaw 24 and passes through the annular locking jaw 24 by deflecting radially outward. Then,
When the locking projection 16 passes through the annular locking jaw 24,
Due to the force exerted on the locking protrusion 16 by the annular locking jaw 24, the pilfer-proof skirt wall 8 is moved upwardly relative to the skirt wall 6 (in this case a plurality of bridging portion 10 is elastically deformed). However, as explained with reference to FIGS. 3 and 5, the above two specific parts 1
In areas other than 2, the inner diameter d2 of the pilfer-proof hem wall 8 and the outer diameter of the skirt wall 6 are set to satisfy dt<D. Therefore, when the pilfer-proof hem wall 8 rises relative to the skirt wall 6 by a distance corresponding to the vertical distance between the two, the pilfer-proof hem wall 8 rises at a portion other than the two specific portions 12. The upper end abuts the lower end of the skirt wall 6, thereby preventing the relative rise of the pilfer-proof skirt wall 8. Thus, the pilfer-proof hem wall 8 is overbounded relative to the skirt wall 6, which causes excessive stress to be generated in the plurality of bridges 10, causing the plurality of bridges to 10 is reliably prevented from being broken. When the container M2 is lowered to the position shown in FIG. It is latched to the bottom surface of. On the other hand, the peripheral edge of the sealing liner 18 of the container lid 2 is brought into close contact with the upper end of the neck section 20, thus sealing the neck section 20.

When opening the neck part 20, the container lid 2 is rotated counterclockwise when viewed from above in FIG. In this way, since the female thread 14 formed on the inner peripheral surface of the skirt wall 6 moves along the male thread 22 formed on the outer peripheral surface of the neck part 20, the skirt wall 6 moves according to the rotation. be forced to rise. However, the locking protrusion 16 formed on the inner peripheral surface of the pilfer-proof hem wall 8
Since it is locked to the lower surface of the annular upper jaw part 24 formed on the outer circumferential surface of 0, it is prevented from rising.

Significant stress is thus created in the bridges 10, which causes the bridges 10 to rupture and the pilfer-proof skirt wall 8 to separate from the skirt wall 6. After that, the portion of the container lid 2 other than the pilfer-proof hem wall 8 freely rises in response to the rotation, and is thus separated from the mouth and neck portion 20, and the mouth portion 20 is opened. The pilfer-proof hem wall 8 remains in the mouth and neck region 20.

The main body of the container lid 2 as described above (that is, the portion excluding the sealing liner 18) is molded from a suitable synthetic resin material by injection molding, compression molding, etc., as already mentioned. In such molding, so-called forced punching can be avoided without the need to use extremely complicated molds.

To explain with reference to FIG. 7-A, the main body of the container M2 is
The whole can be molded using a mold designated 26. The illustrated mold 26 includes a female mold 28 and a male mold 30. A substantially cylindrical mold recess 32 corresponding to the outer shape of the container lid 2 is formed on the lower surface of the female mold 28, which is mounted so as to be movable up and down. On the other hand, the male type 30 is
It includes a stationary male member 32, a pair of movable male members 34, and a movable knockout pin 36. Referring to FIG. 8 together with FIG. 7-A, a protrusion 38 that protrudes upward is formed at the center of the upper surface of the stationary male member 32. As shown in FIG. In the plan view shown in FIG. 8-A, the protrusion 38
extends in the diametrical direction, and both arcuate side surfaces 40 define the two specific portions 12 of the inner circumferential surfaces of the skirt wall 6 and the pilfer-proof hem wall 8. As mentioned above, in the two specific parts 12, there is no female thread 14 on the inner circumferential surface of the skirt wall 6, and there is no locking protrusion on the inner circumferential surface of the pilfer-proof hem wall 8. 16 does not exist. Therefore, on both side surfaces 40 of the protrusion 38, there are no four parts or the like that would cause a forced cut. A through hole 42 passing vertically is formed in the center of the stationary male member 32, and the non-kout pin 36 is inserted into the through hole 42 so as to be movable up and down. Stationary male member 3
Non-kout pin 3 extending downward beyond the bottom surface of 2
The lower end portion of 6 is fixed to a first lifting platform 44. A pair of openings 46 are also formed in the stationary male member 32 around the protrusion 38 and passing through in the vertical direction. Each of the pair of openings 46 has a substantially arcuate cross-sectional shape, and its outer wall surface is inclined downward and radially outward at a predetermined angle. The pair of movable male members 34 are inserted into the pair of openings 46 so as to be movable up and down.

Each of the pair of movable male members 34 has the pair of openings 46
It has a substantially arcuate cross-sectional shape that substantially corresponds to the substantially arcuate cross-sectional shape of . Each of the pair of movable male members 34 extends along the outer wall surface of each of the pair of openings 46, and thus extends downward and radially outward at a predetermined angle.

In the state shown in FIG. 7-A, each of the pair of movable male members 34 projects substantially vertically upwardly beyond the upper surface of the stationary male member 32 to the same height as the upper end of the projection 38. It has a protrusion 501. Such a protrusion 50
The outer surface 52 defines a portion of the inner circumferential surfaces of the skirt wall 6 and the pilfer-proof hem wall 8 other than the two specific portions 12 described above. Therefore, on the outer surface 52 of the masticating protrusion 50, a recess for defining the female thread 14, a recess for defining the locking projection 16, etc. are formed. A pair of movable male members 3
4 extends beyond the lower surface of the stationary male member 32 and also extends through a through opening 5 formed in said first lifting platform 44.
4, and its lower end cannot move relative to the second lifting platform 56 in the vertical direction, but extends downward through the seventh platform 56.
It is connected so that it can move a predetermined amount radially inward from the position shown in Figure A.

When molding the main body of the container lid 2 using the mold 26, first, a mold closing operation is performed to form the female mold 28 and the male mold 3.
0 to the state shown in FIG. 7-A. In this way, the mold cavity is defined by the cooperation of the mold recess 32 in the female mold 28 and the male mold 30. After that, the injection path (
(not shown) is injected into the molding cavity to form the main body of the container lid 2 (in the case of compression molding, prior to the mold closing operation, the female mold 2
The synthetic resin in a heated and molten state may be supplied into the mold recess 32 at step 8, and then the mold closing operation described above may be performed.)
. As can be easily understood by referring to FIG. 7-A, the outer surface of the body of the molded container lid 2 is defined by the inner surface of the mold recess 32 of the female mold 28. On the other hand, the inner surface of the top wall 4 is defined by the upper surface of the knockout pin 36 in the male die 30, the upper surface of the protrusion 38 of the stationary male member 34, and the upper surface of the protrusion 50 of the pair of movable male members 34. Of the inner circumferential surfaces of the skirt wall 6 and the pilfer-proof hem wall 8, the two specified portions I2 are defined by both side surfaces 40 of the protruding portion 38 of the stationary male member 32, and the two specified portions I2 are The parts other than the part 12 are defined by the outer surfaces 52 of the protrusions 50 of the pair of movable male members 34.

The main body of the molded container lid 2 is taken out as follows. First, the female mold 28 is raised to form the container M2.
Separate it from the main body. Next, the first lifting table 44 and the second lifting table 56 are raised to the positions shown in FIG. 7-B. As a result, as shown in FIG. 7-B, the pair of movable male members 34 and the knockout pin 36 are raised, and the main body of the container lid 2 that has been molded accordingly is also raised. On the other hand, since the stationary male member 32 remains stationary without being raised, the protruding portion 38 of the stationary male member 32 moves downward relative to the main body of the container lid 2, and thereby the container M2 separated from the main body of the As described above, forced holes are formed on both side surfaces 40 of the protruding portion 38 (the both side surfaces 40 define the inner circumferential surfaces of the skirt wall 6 and the pilfer-proof hem wall 8 in the two specific portions 12). There are no recesses or the like to hold the container M2 apart, and therefore, no forced extraction is created when the protrusion 38 is separated from the main body of the container M2.

On the other hand, along with FIGS. 7-A and 7-B, FIG. 8-A is a plan view of the male mold 30, and FIG. 8-B is a sectional view taken along line As will be understood by reference, while the pair of movable male members 34 is raised from the position illustrated in FIG. 7-A to the position illustrated in FIG. 7-B, the pair of movable male members 34 34 protrusions 50
is raised relative to the protrusion 38 of the stationary male member 32 and is therefore allowed to move radially inward, and the rise of the pair of movable male members 34 is caused by the rise of the pair of openings 46 of the stationary male member 34. Due to being guided by the inclined outer wall surface, the pair of movable male members 34 are moved radially inward to the positions shown in FIGS. 7-B and 8-B. Thus, the protrusions 50 of the pair of movable male members 34 are connected to the female thread 14 on the inner peripheral surface of the skirt wall 6, the locking protrusion 16 on the inner peripheral surface of the pilfer-proof hem wall 8, and the two above-mentioned The specific portion 12 is spaced radially inward from the inner circumferential portion of the upper end of the pilfer-proof hem wall 8, which is located radially inner than the outer circumferential surface of the skirt wall 6. Next, the first lifting platform 46 is raised to the position shown in FIG. 7-C. As a result, the knockout pin 36 is raised, and the main body of the container lid 2, which has been molded accordingly, is also raised. At this time, the pair of movable male members 34 are not raised, and therefore the protrusions 50 of the pair of movable male members 34 move downward relative to the main body of the container M2. It is separated from the main body of the container lid 2 by. As mentioned above, a pair of movable male members 3
4 has already been moved radially inward, no forced extraction occurs even when the protrusions 50 of the pair of movable male members 34 are separated from the main body of the container M2. Thereafter, the formed main body of the container lid 2 is removed from the knockout pin 36 to a desired location by appropriate means (not shown).

As mentioned above, the body of the molded container lid 2 is removed from the mold 26 without forcible punching, thus creating excessive stress in the complex bridge 10 during removal from the mold 26. It is possible to reliably prevent the plurality of bridge portions 10 from being broken.

Although a specific example of a container lid constructed according to the present invention has been described in detail above, the present invention is not limited to such a specific example, and various modifications can be made without departing from the scope of the present invention. It goes without saying that modifications are possible.

For example, if desired, at least one of the plurality of bridges 10 provided between the skirt wall 6 and the pilfer-proof hem wall 8 may be made into a reinforced bridge with high breaking strength. , at least one weakened line (such weakened line may be a so-called perforation or score) extending in the axial direction is formed on the pilfer-proof hem wall 8, and when opening the neck part 20 of the container, the reinforced bridge is The connecting portion is maintained without being broken, and the weakened line is broken to open the pilfer-proof hem wall 8 from an endless annular shape to an end band shape, thereby causing the locking protrusion 16 to connect to the annular locking jaw of the neck portion 20. 24 and thus pilfer-proof hem wall 8
It is also possible to make the entire container lid 2 including the container lid 2 detachable from the mouth and neck part 20.

In addition, in the specific example described above, two specific parts 12
However, if desired, three or more specific portions may be provided at appropriate intervals in the circumferential direction.

Furthermore, the following points should be noted. mouth and neck 20
The locking protrusion 16 is firmly locked to the annular locking jaw 24 of the container M to ensure that the pilfer-proof property is not damaged (in other words, the container M is secured without breaking the bridging portion lO).
In order to sufficiently reliably prevent the entire body from being separated from the mouth and neck portion 20, it is intended to increase the amount of radially inward protrusion of the locking projection 16. However, when the mold 26 as described above is used to mold the main body of the container M2 without creating so-called forced punches,
The amount of radially inward protrusion of the locking projection 16 is determined by the locking projection 16.
As can be easily understood, the amount of radial protrusion of the locking protrusion 16 is limited to the area indicated by the two-dot chain line 16A in Fig. 8-B. (Beyond this area, seven pairs of movable male members 3
4 is removed from the main body of the container lid 2). As can be understood by comparing the outline of the pair of movable male members 34 and the two-point chain vA16A in FIG. 8-B, at both ends of the locking projection 16, a pair of Although there is substantially no gap between the outline of the movable male member 34 and the two-dot chain line 16A,
A gap exists between the locking projections 16 in the circumferentially intermediate portion thereof. Taking note of this fact, if it is desired to increase the amount of radial protrusion of the locking protrusion 16 as much as possible while avoiding the occurrence of forced extraction, as shown by the two-dot chain line 16B in Fig. 8-[3], It is convenient to form the locking protrusion 16 into a shape in which the amount of protrusion thereof gradually increases from both end portions toward the circumferential middle portion.

<Effects of the Invention> As described in detail above, the container lid of the present invention can be molded without requiring an extremely complicated mold, substantially avoiding forced punching, and therefore can be molded easily from the mold. It is possible to sufficiently reliably prevent the bridge part from breaking when detached,
Furthermore, it is possible to sufficiently reliably prevent breakage of the bridging portion when it is attached to the mouth and neck of the container, which is an excellent and extremely significant effect in practice.

[Brief explanation of drawings]

FIG. 1 is a side view, partially in cross section, of a specific example of a container lid constructed according to the present invention. FIG. 2 is a developed view showing the inner peripheral surfaces of the skirt wall and the pilfer-proof hem wall of the container lid of FIG. 1; FIG. 3 is a sectional view taken along line m--■ in FIG. 1. 4 is a partial sectional view of a specific portion of the container lid of FIG. 1; FIG. FIG. 5 is a partial sectional view of a portion other than a specific portion of the container lid shown in FIG. FIG. 6 is a side view, partially in cross section, of the container lid shown in FIG. 1 attached to the mouth and neck of the container. 7-A, 7-B, and 7-C are cross-sectional views showing how the container lid of FIG. 1 is molded using a mold. FIG. 8-A is a plan view showing the male die in the mold of FIG. 7-A. Fig. 8-B is a sectional view taken along the line ■-■ in Fig. 7-B. 2... Container lid 4... Top wall 6... Skirt wall 8... Pilfer-proof hem wall 10... Bridge portion 12... Specific portion 14... Female thread 16...・Latching protrusion

Claims (1)

[Claims] 1. A circular top wall, a cylindrical skirt wall that hangs down from the periphery of the top wall, and a plurality of bridges disposed at intervals in the circumferential direction to connect the skirt wall to the top wall. A composite material having pilfer-proof characteristics, comprising an annular pilfer-proof hem wall connected to the lower end, and a locking protrusion projecting radially inward on the inner circumferential surface of the pilfer-proof hem wall. In the resin container lid; the locking protrusion is not present on the inner circumferential surface of the pilfer-proof hem wall in at least two specific parts, and the locking protrusion is not present on the inner circumferential surface of the pilfer-proof hem wall in other than the specific parts. The locking protrusion is present, and in the specific region, the inner diameter d_1 of the upper end of the pilfer-proof skirt wall is d_1≧D with respect to the outer diameter D of the lower end of the skirt wall, and in at least a part other than the specific region, is the inner diameter d_2 of the upper end of the pilfer-proof hem wall, and the outer diameter D of the lower end of the skirt wall is D>d_
2. A container lid characterized by: 2. The two specific parts are located diametrically opposite each other,
A container lid according to claim 1. 3. The container lid according to claim 1 or 2, wherein d_1-D≦1.0 mm. 4. The container lid according to any one of claims 1 to 3, wherein D-d_2≧0.7 mm. 5. The container lid according to any one of claims 1 to 4, wherein the inner peripheral surface of the skirt wall is formed with a female thread interrupted at the specific location.