JP3281225B2 - Container cap - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cap capable of pouring out the contents of a container without removing it from the container, and more particularly to a hinge mechanism used for such a cap.

[0002]

2. Description of the Related Art As a cap for a container, a cap skirt fitted or screwed onto the mouth and neck of the container, an overcap covering a top plate portion of the cap skirt, and an overcap swinging with respect to the cap skirt. 2. Description of the Related Art There has been known a hinge mechanism which is integrally formed of a synthetic resin and a hinge mechanism for supporting the hinge mechanism. Such a hinged cap, when pouring out the contents of the container, it is only necessary to swing the overcap around the swing axis of the hinge mechanism, it is not necessary to remove the entire cap from the container,
In recent years, it has been widely used as a cap for containers for liquid seasonings and the like.

[0003] The hinge mechanism of the hinge-type cap is as follows.
For example, Japanese Patent Publication No. 3-53182, Japanese Patent Publication No. 63-1
Those skilled in the art, as described in JP-A-7707, JP-A-63-7657, JP-A-3-11655, JP-A-6-21885, or JP-A-5-86850, use a three-point hinge. Is generally used. Such a three-point hinge is composed of a hinge body that connects the cap skirt and the overcap to be able to swing with each other, and a pair of elastic pieces disposed on both sides of the hinge body and pulling the overcap in a closed state or an open state. ing.

In such a three-point hinge, for example, when the overcap is swung from the open state to the closed state, the elastic piece is gradually moved until the overcap reaches a predetermined position (hereinafter referred to as a conceivable point). Elongate. Therefore, in this process, the user feels resistance to swinging the overcap. When the overcap exceeds the expected point, the elastic piece contracts due to its own elastic restoring force and pulls the overcap in the direction of the closed state. The resistance (click feeling) felt when the overcap exceeds the thought point, and the operation characteristics when moving from the thought point to the closed state or when moving from the thought point to the open state (snap property)
Is determined by the size, elastic modulus, elongation, etc. of the elastic piece,
If the tensile force at the conceivable point is large, it is considered that the snapping property or the clicking feeling is good.

[0005]

However, if the tensile force of the elastic piece is excessively increased in order to improve the snapping property or click feeling of the hinge mechanism, the stress generated in the elastic piece increases. Further, since the elastic pieces have different amounts of elongation between the side close to the hinge body and the opposite side, the stress distribution tends to be non-uniform. Furthermore, depending on the connection state and the position, the elastic piece is twisted and a local stress concentration occurs.
The torsion, large stress and stress concentration of the elastic piece cause early fatigue failure.

For this reason, conventionally, in order to suppress the torsion, the entire hinge mechanism is projected outward from the side surfaces of the overcap and the cap skirt, or the durability is maintained even if a large stress is generated. And the area of the elastic piece was increased.

However, when the hinge mechanism is protruded or the elastic piece is enlarged, the fingertip hits the hinge mechanism,
There is a problem that the operability of the cap is impaired.

Accordingly, an object of the present invention is to provide a cap provided with a hinge mechanism having good snapping properties, durability and operability.

[0009]

In order to achieve the above object, a container cap according to the present invention is directly attached to the mouth and neck of the container and has a cap skirt having a substantially cylindrical outer peripheral surface, and a cap skirt. An overcap for covering the plate part and closing the spout of the container contents provided on the top plate part, and supporting the overcap with respect to the cap skirt in a swingable manner between a closed state and an open state. A hinge body that is integrally molded from synthetic resin, the hinge mechanism includes a hinge body that supports the cap skirt and the overcap so that they can swing relative to each other, and both ends disposed on both sides of the hinge body. A three-point hinge having a cap skirt and a pair of elastic pieces joined to the overcap, respectively; and
Each end of the elastic piece is joined in an arc along the outer peripheral surface of the corresponding cap skirt and overcap. In addition, the overcap is set 180
In the 180-degree opened state in which the lid has been swung 180 degrees, the elastic piece is formed into a substantially arc shape between the cap skirt and the overcap, and further, the thickness of the elastic piece is gradually increased toward the end. I have. Note that the 180-degree open state is a state immediately after the cap is taken out of the mold of the injection molding apparatus, and since the elastic piece has no stress or is minimal, the 180-degree open state is referred to in this specification. It is in the reference state.

In such a configuration, the thickness of the elastic piece is
Since the stress is larger on the end side where stress concentration is more likely to occur, the stress distribution is made uniform.

When the value of a factor (W / d) determined by the thickness (W) of the end of the elastic piece and the thickness (d) of the center of the elastic piece is 1.2 to 5.0. In addition, uneven extension deformation of the end of the elastic piece is prevented, and no excessive resistance is generated when the lid is closed.

Further, a shortest distance (PI, PH) between a center point (R1, R2) defining an arc of the arc-shaped portion of the elastic piece and an extension of the swing axis (B) of the hinge body, and The distance (L) between the midpoint (M) of the hinge body and the side surface of the elastic piece
Assuming that the value of the factor (PI / LI, PH / LH) determined by (I, LH) is 0.3 to 0.9, uneven extension deformation between the inner side surface and the outer side surface of the elastic piece may occur. It is prevented and also a large snap force is obtained.

[0013] Even when the joint surface between each end of the elastic piece and the corresponding cap skirt and overcap is inclined toward the hinge body, the non-uniform extension between the inner surface and the outer surface of the elastic piece. Deformation can be prevented.

Further, when the lid is opened at 180 degrees, a concave portion may be formed on the upper surface of the hinge body along the pivot axis. In such a case, the resistance of the hinge body against the engagement of the folded over cap at the time of closing the lid is reduced. This resistance is referred to as a lid-closing resistance sensation, and a good lid-closing resistance sensation indicates that the resistance when the overcap is closed is small.
On the other hand, a poor closing resistance feeling not only indicates that the resistance when closing the overcap is large, but also indicates that the overcap once locked releases the locking.

In the above configuration, the shape of the joint of the elastic pieces is formed as an arc, but may be formed as a straight line.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the drawings.

1 to 3, reference numeral 10 indicates a hinge-type cap according to the present invention. This cap 1
0 is a cap skirt 12 and an overcap 14
And a hinge mechanism 16.

The cap skirt 12 is a cup-shaped member which is directly attached to the mouth and neck portion 20 of the container 18 by fitting or screwing, and has a substantially cylindrical portion 22 surrounding the mouth and neck portion 20.
And a top plate portion 24 that is in contact with the distal end surface of the mouth and neck portion 20. An opening 26 is formed in the center of the top plate portion 24, and this opening serves as a spout 26 for the container contents. Further, a substantially cylindrical member 28 with a tongue piece protrudes from the top plate portion 24 so as to surround the spout port 26, and this is for facilitating the pouring of the container contents. . Further, the inner surface of the top plate portion 24 (the mouth and neck portion 2)
The inner ring that is in close contact with the inner peripheral surface of the distal end of the mouth and neck portion 20 to prevent leakage of the contents of the container from between the outer peripheral surface of the mouth and neck portion 20 and the inner peripheral surface of the cap skirt 12. 30 are protruded. If necessary, a sheet or film (not shown) composed of a single layer or a multilayer having an oxygen gas barrier property may be provided on the inner surface of the top plate portion 24 from the viewpoint of preventing decay of the contents of the container. preferable.

The overcap 14 covers the top plate portion 24 of the cap skirt 12 and closes the spout 26. The overcap 14 is swingably attached to the cap skirt 12 via the hinge mechanism 16. ing. The inner surface of the overcap 14 (the surface on the side of the cap skirt 12 in the closed state in FIG. 3) is fitted into the spout 26 of the cap skirt 12 at the time of closing the lid, thereby preventing leakage of the contents of the container from the spout 26. A cylindrical member 32 is provided. In order to maintain the overcap 14 in a closed state, a locking means is provided. Various types of locking means are conceivable. In the illustrated embodiment, if the locking ring 34 provided on the outer peripheral portion of the top plate portion 24 of the cap skirt 12 and the inner peripheral surface of the overcap 14 are tight. And this is used as locking means.

The hinge mechanism 16 is a so-called three-point hinge, and includes a hinge body 36 and elastic pieces 38 arranged on both sides of the hinge body 36. As shown in FIGS. 4 and 5, the hinge body 36 includes a portion 36 a protruding outward along the upper edge of the substantially cylindrical portion 22 of the cap skirt 12, and an upper edge of the overcap 14. (An edge on the side that comes into contact with the cap skirt 12 when the lid is closed) and a portion 36b protruding outwardly. These portions 36a and 36b are integrally joined at the position of the surface A. The overcap 14 is swung about a horizontal axis on the coupling surface A as a swing axis B. In this embodiment, as shown in FIG. 5, each of the portions 36a and 36b of the hinge main body 36 has a substantially triangular prism shape, and the connecting portion is made thinnest. A concave portion 36c is formed on the upper surface of the coupling portion along the direction of the swing axis B. The concave portion 36c reduces resistance to the folding of the hinge body 36 and the locking of the overcap 14 when the lid is closed. Become smaller.

Both ends of each elastic piece 38 of the hinge mechanism 16 are joined to the cap skirt 12 and the overcap 14, respectively. More specifically, 18
In the 0 degree open state, as shown in FIGS. 4, 6 and 7, both ends of the elastic piece 38 are respectively connected to the cap skirt 1.
2 and the end surfaces 41 and 43 of the concave portions 40 and 42 formed on the outer peripheral surface of the overcap 14. As can be seen from FIG. 4, each joint end 38a, 38b forms an arc with respect to the cap skirt 12 and the overcap 14 along the outer peripheral surface thereof. The center of this arc is a point on the center axis of the cap skirt 12 and the overcap 14. Also, as shown in FIG.
The cross-sectional shape of the central portion of 8 is rectangular. As can be understood from FIG. 8, the concave portions 40 and 42 of the cap skirt 12 and the overcap 14 extend in the vertical direction (a direction parallel to the central axis of the cap skirt 12 and the overcap 14). 4
Reference numerals 1 and 43 are inclined surfaces that are inclined upward in the direction toward the hinge body 36.

The inside of each elastic piece 38 (the hinge body 3)
The side surface (hereinafter, referred to as “inner surface”) 38c and the opposite side surface (hereinafter, referred to as “outer surface”) 38d are respectively provided at the midpoint M of the hinge body 36 and the cap skirt 12 or the overcap 14. Are placed on a plane (plane C and plane B in FIG. 4) parallel to a vertical reference plane P formed by the center axis of the vertical axis.

Further, in the 180-degree opened state, when viewed from the direction of the swing axis B of the hinge main body 36, the shape of the elastic piece 38 is substantially circular. More specifically, FIG.
6 and 4 which are end views along the line VI-VI.
As shown in FIG. 7, which is an end view along line I, the lower surface of the elastic piece 38 has an arc shape from one joint end 38a to the other joint end 38b. Also, the elastic piece 3
8 also has an arc shape between the intersection X1 with the extension of the outer peripheral surface of the cap skirt 12 and the intersection X2 with the extension of the outer peripheral surface of the overcap 14. Further, the upper surface of the elastic piece 38 extends linearly from the intersection X1 to the joint end 38a. The direction of this linear portion substantially matches the normal direction at the intersection X1 of the arc. Similarly, the space from the intersection X2 to the joint end 38b is also linear. by this,
The thickness of the elastic piece 38 is larger at the joint ends 38a and 38b.

When such an elastic piece 38 swings the overcap 14 from the opened state to the closed state by 180 degrees, the linear distance between the joining ends 38a and 38b gradually increases to the conceivable point. Go. Since the elastic piece 38 is made of an elastic material and has a minimum stress in the 180-degree opened state, the elastic restoring force increases as the distance between the joining ends 38a and 38b increases. Go. Therefore, from the 180-degree opened state to the conceived point, a pulling force acts on the overcap 14 to return to the 180-degree opened state.

When the overcap 14 reaches a conceivable point,
The distance between the joint ends 38a and 38b of the elastic piece 38 is maximized. At this time, the elastic pieces 38 are substantially in a straight line. When the overcap 14 is further swung, a pulling force acts on the overcap 14 in a direction to close the lid. Thus, even if the hand is released from the overcap 14, the overcap 14 automatically swings in the direction of the closed state. Although the lid is not completely closed due to the resistance force of the hinge body 38, the overcap 14 is forcibly fitted to the locking ring 34 in the end, so that the closed state shown in FIG. Become. At this time, the elastic pieces 38 project outward.

The overcap 14 is moved from the closed state to 18
In the case where the overcap 14 is swung to the 0-degree open state, resistance is added to the swing of the overcap 14 up to the expected point, and when the point exceeds the expected point, the overcap 14 is automatically opened (not necessarily the 180-degree open state). And stabilize in that state.

When the overcap 14 is swung in this manner, the hinge mechanism 16 according to the present invention employs the elastic piece 3
8, inner surface 38c and outer surface 38d, especially inner surface 38c
And the end of the outer surface 38d is located at the midpoint M of the hinge body 36.
The elastic piece 38 is hardly twisted because it moves on the planes C and D parallel to the reference plane P passing through the elastic piece 38. For this reason, there is no loss of the tensile force due to the twist, and a good snapping property or a click feeling can be obtained. In addition, there is an effect that stress due to twisting does not occur.

Further, as described above, in the present invention, the thickness of the elastic piece 38 is increased toward the joining end portions 38a and 38b. When the overcap 14 is rocked, the elastic piece 38 generates a larger stress at the joint ends 38a and 38b. Therefore, by increasing the thickness of the joint ends 38a and 38b, the stress distribution can be made uniform. Become. Now, the thickness of the joining end portions 38a and 38b with respect to the inner surface 38c is set to W.
I, the thickness of the joining ends 38a, 38b with respect to the outer surface 38d is WH, the average thickness of the joining ends 38a, 38b is W,
When the thickness of the central portion of the elastic piece 38 is d (see FIGS. 6 and 7), a factor (W / d = (W
When I + WH) / 2d) is small, specifically, smaller than 1.2, stress is concentrated on the joint ends 38a and 38b of the elastic piece 38 when the overcap 14 swings, and the joint end There is a possibility that uneven elongation deformation or cutting of 38a and 38b may occur. On the other hand, when the factor (W / d) is large, specifically, when the factor (W / d) is larger than 5.0, the resistance at the time of closing the cover may become too large, and the operability may be deteriorated.
Therefore, if the shape of the elastic piece 38 is determined so that the factor (W / d) becomes 1.2 to 5.0, the resistance at the time of closing the lid is suppressed, and the stress on the joint ends 38a and 38b is reduced. Concentration can be prevented, which is preferable.

Further, both ends 38a, 38b of the elastic piece 38
Are inclined end surfaces 41, 43 of concave portions 40, 42 provided in the cap skirt 12 and the overcap 14, respectively.
Is joined to. This is because the recess 4
By inclining the end surfaces 41 and 43 of the elastic pieces 38, the difference in the total length between the inner surface 38c and the outer surface 38d of the elastic piece 38 is increased in advance, and the joining ends 38a, The purpose of the present invention is to suppress the concentration of stress caused by the difference between the maximum elongation between the connection ends 38a and 38b and the maximum elongation between the joining ends 38a and 38b on the outer surface 38d.

Further, in the present invention, the distances in the swing axis direction from the intermediate point M of the hinge main body 36 to the inner side surface 38c and the outer side surface 38d of the elastic piece 38 are LI and LH, respectively (see FIG. 4). The shortest distances from the extension of the pivot axis B of the hinge body 38 to the center points R1 and R2 defining the arcs of the inner surface 38c and the outer surface 38d of the elastic piece 38 are respectively P
I and PH were set (see FIGS. 6 and 7), and the factors (PI / LI) and (PH / LH) determined by these distances were in the range of 0.3 to 0.9. This factor (PI /
LI) and (PH / LH) are experimentally determined. If smaller than 0.3, the snap force is small, and the resistance when the overcap 14 exceeds the expected point, that is, the click feeling is small. In addition, the position of the overcap 14 in the open state is not determined, and the position becomes unstable. If the factors (PI / LI) and (PH / LH) exceed 0.9, the elastic piece 38 has a non-uniformly elongated shape in the extension direction, and a loss occurs in the tensile force of the elastic piece 38. As a result, the snap property deteriorates. Therefore, this factor (PI /
(LI) and (PH / LH) are preferably in the range of 0.3 to 0.9. However, in the case of 0.4 to 0.7, a sharper click feeling can be obtained and repeated. This is more preferable because it is difficult to form a shape that is unevenly extended by swinging.

Although the preferred embodiments of the present invention have been described in detail, it goes without saying that the present invention is not limited to the above embodiments. For example, in the above embodiment, as shown in FIG.
Are arcs centered on the center axis of the cap 10 on both sides (corresponding to (a) in FIG. 9), but as schematically shown in (b) and (c) of FIG. Only a circular arc may be formed, or as shown in FIGS. 9D to 9F, it may be arranged on the deep side of the concave portions 40 and 42. In the present specification, the form as shown in FIG.
"It forms an arc along the outer peripheral surface."

Also, the joint ends 38a, 38 of the elastic piece 38
The shape of b does not need to be an arc shape, and may be a straight line along the outer peripheral surface of the cap skirt 12 or the overcap 14. This “forming a straight line along the outer peripheral surface” means that the horizontal cross-sectional shape of at least one surface of the elastic piece 38 is centered on the center axis of the cap 10 as shown in FIGS. The form or elastic piece 3 which becomes a string
8 means that the horizontal cross-sectional shape of at least one surface is a straight line. Of course, it is also possible to adopt a configuration in which an arc is formed on one surface side and a straight line is formed on the other surface side.

Furthermore, in the above embodiment, when the elastic piece 38 is extended, the elastic piece 38 has a substantially rectangular shape. However, from the viewpoint of making the stress distribution uniform, the width is the narrowest at the middle portion, and the width is larger at the end portion. The shape may be as follows.

[0034]

EXAMPLES Next, the following table shows the results of opening and closing tests of caps made according to the above embodiment. In this table, Examples 1 to 4 used samples having the forms shown in FIGS. Also, in Examples 5 and 6, the shapes of the joint ends 38a and 38b of the elastic piece 48 are changed as shown in FIG.
The linear shape shown in FIG. Further, Comparative Examples 1 to 3
Are the factors (W / d), (PI / LI) and (PH / L
H) shows the results using samples that deviated from the above range. In Comparative Examples 4 and 5, the hinge mechanism 1
In place of the elastic piece 38 of No. 6, an elastic piece whose projecting direction of the elastic piece did not reverse in the process of closing and opening the lid was used. In particular, Comparative Example 4 shows the result of using a sample having a configuration in which the back of the elastic piece fits inside the outer periphery of the cap.
This is a sample corresponding to -11655. Comparative Example 5 shows the result of using a sample having a configuration in which the back of the elastic piece of Comparative Example 4 protrudes outward from the outer peripheral surface of the cap, and is a sample corresponding to Japanese Utility Model Laid-Open No. 63-7657.

[0035]

[Table 1]

From this table it can be seen that Examples 1 to 6 constructed according to the invention gave very good results.

Incidentally, in Comparative Examples 1 to 3 using samples in which the factors (W / d), (PI / LI) and (PH / LH) deviated from the above ranges, the clicking feeling or the closing resistance was not so good. In some cases, the elastic piece was damaged when the overcap was opened and closed 1000 times. In addition, it can be seen that Comparative Example 4 is not preferable because the lid closing feeling is large and judged to be defective, or the shape and size of the spout 26 are limited. Further, when the elastic piece was damaged by opening and closing the cover 1000 times, the click feeling from the idea to the closing of the cover was smaller than that before opening and closing the cover 1000 times. Is acceptable. Also, for Comparative Example 5,
The result was that the smoothness of the hinge mechanism was poor.

Here, the "smoothness of the hinge mechanism" is a concept indicating the ratio of the hinge mechanism protruding outward from the outer peripheral surface of the cap. And "smoothness is good"
Means that the ratio of protrusion is small. When fitting or screwing the cap on the container, it is necessary to align the cap in a certain direction in advance. Poor smoothness causes clogging between the caps in the alignment line and mechanical interference with the line, so that the cap cannot travel smoothly on the alignment line.

[0039]

As described above, according to the present invention, since the elastic piece of the hinge mechanism is prevented from being twisted, the elastic restoring force generated in the elastic piece is efficiently used as a snap force for pulling the overcap. It is possible to do. Therefore, a good snap property and a click feeling can be obtained.

Further, since the elastic restoring force of the elastic piece can be efficiently used, the size of the elastic piece can be reduced, and the hinge mechanism for the cap can be reduced. This improves the handleability or the operability, and provides an excellent effect in that the appearance or smoothness is good (that is, the ratio of the hinge mechanism protruding outward of the outer peripheral surface of the cap is small).

Further, according to the present invention, since the distribution of the stress generated in the elastic piece is made uniform, it can sufficiently withstand repeated use.

[Brief description of the drawings]

FIG. 1 is a plan view of a cap of a container according to the present invention in a 180-degree opened state.

FIG. 2 is a sectional view taken along the line II-II of FIG.

FIG. 3 is a partially sectional side view showing the cap of FIG. 1 in a closed state.

FIG. 4 is an enlarged plan view showing a hinge mechanism in the cap of FIG. 1 in detail.

5 is a cross-sectional view of the hinge body of the hinge mechanism, taken along line VV of FIG. 4;

FIG. 6 shows an elastic piece in the hinge mechanism.
FIG. 6 is an end view along the line VI.

FIG. 7 shows the elastic piece in the hinge mechanism.
FIG. 7 is an end view along the line VII.

FIG. 8 is a view along the line VIII-VIII in FIG. 4;

FIG. 9 is a schematic explanatory view showing various forms of an end of an elastic piece.

FIG. 10 is a schematic explanatory view showing various other forms of the end of the elastic piece.

[Explanation of symbols]

10 cap, 12 cap skirt, 14 overcap, 16 hinge mechanism, 18 container, 20
Mouth and neck, 22: substantially cylindrical portion, 24: top plate portion, 26 ...
Outlet, 36: hinge body, 38: elastic piece, 40, 42
... recesses.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Eiji Ishizuki, inventor 18-13, Kamitamari, Tamari-mura, Niiji-gun, Ibaraki Pref. Kureha Chemical Industry Co., Ltd. (56) References JP 63-317467 (JP, A) 63-7657 (JP, U) JP-A-2-37857 (JP, U) JP-A 57-151244 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) B65D 47 / 08

Claims (4)

(57) [Claims] 1. A cap skirt which is directly attached to the mouth and neck of a container and has a substantially cylindrical outer peripheral surface, and is provided on the top plate portion so as to cover a top plate portion of the cap skirt.
An overcap for closing a spout of the contents of the container, a hinge mechanism for swingably supporting the overcap with respect to the cap skirt between a closed state and an open state, and a synthetic resin. Wherein the hinge mechanism comprises a hinge body that supports the cap skirt and the overcap so that they can swing relative to each other; and a cap skirt that is disposed on both sides of the hinge body and has both ends. A pair of elastic pieces joined to the overcap, each end of the elastic pieces being joined in an arc along the outer periphery of the corresponding cap skirt and the overcap, and closed. In the 180-degree open state in which the overcap is swung 180 degrees from the lid state, the elastic piece Becomes substantially arcuate between the over bets and the overcap, the thickness of the elastic piece is gradually increased as the end side, the cap of the container, characterized in that. 2. A cap skirt which is directly attached to the mouth and neck of the container and has a substantially cylindrical outer peripheral surface, and is provided on the top plate portion so as to cover a top plate portion of the cap skirt.
An overcap for closing a spout of the contents of the container, a hinge mechanism for swingably supporting the overcap with respect to the cap skirt between a closed state and an open state, and a synthetic resin. Wherein the hinge mechanism comprises a hinge body that supports the cap skirt and the overcap so that they can swing relative to each other; and a cap skirt that is disposed on both sides of the hinge body and has both ends. A pair of elastic pieces joined to the overcap, each end of the elastic piece being joined in a straight line along a corresponding outer periphery of the cap skirt and the overcap, and closed. In the 180-degree open state in which the overcap is swung 180 degrees from the lid state, the elastic piece is the cap. Cart and the becomes substantially arcuately between the overcap, the thickness of the elastic piece is gradually increased as the end side, the cap of the container, characterized in that. 3. A factor (W / d) determined by a thickness (W) of an end portion of the elastic piece and a thickness (d) of a central portion of the elastic piece.
3. The cap of claim 1, wherein the value of １．２ is 1.2 to 5.0. 4. 4. A distance (PI, PH) between a center point (R1, R2) defining an arc of the arc-shaped portion of the elastic piece and an extension of a swing axis (B) of the hinge body, and , A factor (PI / LI, PH) determined by a distance (LI, LH) between an intermediate point (M) of the hinge body and a side surface of the elastic piece.
The container cap according to any one of claims 1 to 3, wherein the value of (/ LH) is from 0.3 to 0.9.