Caps for beverage containers and beverage containers

Abstract

The present invention provides a cap for a beverage container that can improve the airtightness between the cap and the spherical stopper member in a gas-pressure-sealed container. [Solution] A cylindrical cap for a beverage container, which is attached to the outer circumference of the opening of a bottle-shaped container body, and the opening of the cap is sealed by a spherical stopper member, comprising an outer cylinder portion attached to the outer circumference of the opening of the container body, and an inner cylinder portion integrally molded inside the outer cylinder portion and made of an elastic material, wherein the inner cylinder portion has a cylindrical holding portion into which the stopper member can be elastically held by inserting the stopper member from the end on the container body side in the axial direction, and the holding portion has a projection that seals the space between the holding portion and the stopper member by elastically contacting the surface of the stopper member while holding the stopper member, and the projection is an annular projection provided along the circumferential direction on the inner circumference of the holding portion.

Description

Technical Field

[0001] The present invention relates to a cap for a beverage container and a beverage container.

Background Art

[0002] Conventionally, as a container for a carbonated beverage called ramune, there is a bottle-type container in which a spherical plug member made of a glass ball is accommodated. This type of beverage container includes a screw-on type container (hereinafter also referred to as a screw-on container) and a container of a type in which the plug is applied by the pressure of carbon dioxide gas (hereinafter also referred to as a gas-pressure plugging type container).

[0003] The screw-on container is a container in which a cylindrical cap with an opening plugged by previously holding a spherical plug member is screwed onto the opening of the container body (see, for example, Patent Document 1). On the other hand, in the gas-pressure plugging type container, after a carbonated beverage is injected into the container body in which a spherical plug member is accommodated, a cylindrical cap is attached to the outer periphery of the opening of the container body, and then the orientation of the container is inverted up and down so that the opening of the cap faces downward, whereby the plug member that has fallen to the opening of the cap and closed the opening is plugged by the pressure of the carbon dioxide gas in the container (see, for example, Patent Document 2).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] As described above, in the screw-on container and the gas-pressure plugging type container, the method of plugging with the spherical plug member is different. Therefore, the characteristics required for the seal portion that contacts the spherical plug member are different between the screw-on container and the gas-pressure plugging type container.

[0006] Therefore, in view of these problems, the present invention aims to provide a beverage container cap and a beverage container that can improve the airtightness between the cap and the spherical stopper member in a gas-pressure-sealed container cap. [Means for solving the problem]

[0007] The beverage container cap according to the present invention is a cylindrical cap attached to the outer circumference of the opening of a bottle-shaped container body, wherein the opening of the cap is sealed by a spherical stopper member, and comprises an outer cylinder portion attached to the outer circumference of the opening of the container body, and an inner cylinder portion integrally molded inside the outer cylinder portion and made of an elastic material, wherein the inner cylinder portion has a cylindrical holding portion into which the stopper member is inserted from the end on the container body side in the axial direction and the stopper member is elastically held, and the holding portion has a projection that seals the space between the holding portion and the stopper member by elastically contacting the surface of the stopper member while holding the stopper member, and the projection is an annular projection provided along the circumferential direction on the inner circumference of the holding portion. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a cap for a beverage container and a beverage container that can improve the airtightness between the cap and the spherical stopper member in a cap for a gas-pressure-sealed container. [Brief explanation of the drawing]

[0009] [Figure 1] This is a cross-sectional view showing an example of a beverage container according to one embodiment of the present invention, in which the cap is holding a spherical stopper member. [Figure 2] This figure shows an example of a container body in a beverage container according to one embodiment of the present invention, and shows the state in which a spherical stopper member is housed. [Figure 3] This is a cross-sectional view showing an example of a beverage container according to one embodiment of the present invention, and it shows the state before the cap is attached to the container body. [Figure 4] This is a cross-sectional view showing an example of the inner cylinder portion of a beverage container according to one embodiment of the present invention. [Figure 5] This is a cross-sectional view showing an example of a beverage container according to one embodiment of the present invention, in which the cap does not hold a spherical stopper member. [Figure 6] This is a cross-sectional view showing a magnified portion of Figure 5 (the area indicated by the dashed line). [Figure 7] This is a cross-sectional view showing an enlarged portion of Figure 1 (the area indicated by the dashed line). [Modes for carrying out the invention]

[0010] The following description will refer to the drawings and explain a beverage container cap and beverage container according to one embodiment of the present invention. Note that the embodiments shown below are merely examples, and the beverage container cap and beverage container according to the present invention are not limited to the embodiments described below.

[0011] The beverage container 1 shown in Figure 1 can be used, for example, as a container for carbonated beverages such as ramune. The type of beverage that can be contained is not particularly limited as long as it is a carbonated beverage, and examples include carbonated drinks such as ramune, cider, and cola, as well as carbonated alcoholic beverages such as beer and champagne.

[0012] The beverage container 1 comprises a bottle-shaped container body 2 and a cap 3 attached to the outer circumference of the opening 21 of the container body 2. The beverage container 1 also includes a spherical stopper member 4 that seals the opening 33 of the cap 3.

[0013] In this specification, the axial direction of the beverage container 1 is referred to as "axial direction D1" (see Figure 1). Axial direction D1 is the axial direction of the container body 2 and the cap 3. Axial direction D1 is the direction connecting the bottom and the opening of the beverage container 1. In this specification, in axial direction D1, the direction from the bottom to the opening of the beverage container 1 is also referred to as the "forward direction," and the direction from the opening to the bottom of the beverage container 1 is also referred to as the "rear direction." In this specification, the radial direction of the beverage container 1 is also referred to as "radial direction D2" (see Figure 1). Radial direction D2 is the radial direction of the container body 2 and the cap 3, and is perpendicular to the axial direction D1.

[0014] As shown in Figure 2, the container body 2 is a bottle-shaped container capable of holding a beverage and a spherical stopper member 4. As shown in Figure 1, the opening 21 of the container body 2 is sealed by a cap 3 and a stopper member 4. The form of the container body 2 is not particularly limited as long as it is bottle-shaped and capable of holding a beverage and a stopper member 4. In the example shown in Figure 2, the container body 2 has a constricted portion 22 in the central part in the axial direction D1. The container body 2 also has an upper portion 23 located on the opening side (front side, upper side in Figures 1 and 2) of the constricted portion 22 in the axial direction D1, and a lower portion 24 located on the bottom side (rear side, lower side in Figures 1 and 2) of the constricted portion 22 in the axial direction D1. The space in the upper portion 23 and the space in the lower portion 24 are in communication via the space in the constricted portion 22. The constricted portion 22 has dimensions that prevent the stopper member 4 from falling into the lower portion 24 when the stopper member 4 is housed in the upper portion 23. The provision of the constricted portion 22 prevents the plug member 4 inside the upper portion 23 from falling into the lower portion 24.

[0015] The container body 2 has an opening 21 at its front end (upper end in Figure 2) that serves as a drinking and drinking port. A male threaded portion 251 is formed on the outer circumference of the opening 21 of the container body 2. Specifically, the container body 2 has a cylindrical peripheral wall 25 extending in the axial direction D1 at its front end. The opening 21 is formed inside the peripheral wall 25. A male threaded portion 251 is formed on the outer circumference of the peripheral wall 25. The male threaded portion 251 can be screwed into the female threaded portion 311 of the cap 3, which will be described later. Furthermore, a notch 252 is formed on the inner circumference of the opening 21 of the bottle body 2. Specifically, a notch 252 is formed on the inner circumference of the peripheral wall 25. The notch 252 is formed by the fact that the inner diameter from the front end of the opening 21 to a predetermined position in the axial direction D1 (i.e., the inner diameter of the front region of the peripheral wall 25) is smaller than the inner diameter from the predetermined position to the rear of the opening 21 (i.e., the inner diameter of the rear region of the peripheral wall 25). In the examples shown in Figures 1, 3, 5 to 7, the notch 252 is the portion in which the cross-section cut along the axial direction D1 is L-shaped on the inner circumference. That is, the notch 252 is formed by cutting an L-shaped cross-section in the inner surface of the peripheral wall 25 when viewed from the radial direction D2. The notch 252 is the portion in the cap 3 into which the opposing portion 324, described later, is fitted. The notch 252 has an annular support surface (hereinafter also referred to as the annular support surface) 253 at the predetermined position in the axial direction D1 of the peripheral wall 25. The annular support surface 253 is an annular surface having a predetermined width in the radial direction D2. Furthermore, the notch 252 has a cylindrical support surface (hereinafter also referred to as a cylindrical support surface) 254 in the region from a predetermined position in the axial direction D1 on the peripheral wall 25 to the front end. The cylindrical support surface 254 is a cylindrical inner circumferential surface having a predetermined length in the axial direction D1. The annular support surface 253 can support the opposing portion 324 of the cap 3 in the axial direction D1. The cylindrical support surface 254 can support the opposing portion 324 of the cap 3 in the radial direction D2. In other words, the notch 252 can support the opposing portion 324 of the cap 3 in the axial direction D1 and radial direction D2 by the annular support surface 253 and the cylindrical support surface 254.

[0016] The material of the container body 2 is not particularly limited as long as it can accommodate a beverage containing carbon dioxide gas and the plug member 4. The material of the container body 2 is, for example, a synthetic resin such as polyethylene terephthalate (PET). The container body 2 made of synthetic resin has advantages such as being lightweight and easy to handle compared to container bodies made of other materials (such as glass). Also, when both the container body 2 and the cap 3 are made of synthetic resin, a manufacturer of synthetic resin containers can manufacture both the container body 2 and the cap 3 from synthetic resin. Therefore, when both the container body 2 and the cap 3 are made of synthetic resin, it is easier to suppress the manufacturing cost of the beverage container 1 compared to the case where the container body 2 is made of, for example, glass and the cap 3 is made of synthetic resin. Note that the material of the container body 2 may be a material other than synthetic resin.

[0017] As shown in FIGS. 1, 3, and 5, the cap 3 is a cylindrical cap attached to the outer periphery of the opening 21 of the bottle-shaped container body 2. Specifically, the cap 3 is attached to the outer periphery of the peripheral wall 25 that forms the opening 21. In the present embodiment, the cap 3 is configured to be detachably attached to the outer periphery of the peripheral wall 25. In the examples shown in FIGS. 1, 3 to 5, the cap 3 includes an internal thread portion 311 that can be screwed with an external thread portion 251 formed on the outer periphery of the peripheral wall 25 (see FIGS. 1 to 3 and 5) of the container body 2. By screwing the internal thread portion 311 and the external thread portion 251 together, the cap 3 can be attached to the outer periphery (the outer periphery of the peripheral wall 25) of the opening 21 of the container body 2. Also, by releasing the screwing of the internal thread portion 311 and the external thread portion 251, the cap 3 can be removed from the outer periphery (the outer periphery of the peripheral wall 25) of the opening 21 of the container body 2.

[0018] The cap 3 is a cap for a beverage container in which the opening 33 of the cap 3 is sealed by a spherical plug member 4. When the cap 3 is attached to the outer periphery of the opening 21 of the container body 2, the opening 33 of the cap 3 is sealed (closed) by the plug member 4, so that the opening 21 of the container body 2 is sealed (closed) by the cap 3 and the plug member 4. In the present embodiment, the cap 3 houses a beverage containing carbon dioxide gas and the plug member 4 in the container body 2, and the orientation of the beverage container 1 in which the cylindrical cap 3 is attached to the outer periphery of the opening 21 of the container body 2 is inverted upside down so that the opening 33 of the cap 3 is located on the lower side and drops to the opening 33 of the cap 3. The cap 3 for a beverage container is a type in which the opening 33 of the cap 3 is closed by the plug member 4 receiving the pressure of carbon dioxide gas (hereinafter, also referred to as a gas pressure sealing type).

[0019] The cap 3 includes an outer cylinder portion 31 and an inner cylinder portion 32. The outer cylinder portion 31 is configured to be attached to the outer periphery of the opening 21 of the container body 2. In the present embodiment, the outer cylinder portion 31 is configured to be attached to the outer periphery of the peripheral wall 25 that forms the opening 21 of the container body 2. Further, the outer cylinder portion 31 is configured to be detachably attached to the outer periphery of the peripheral wall 25. In the example shown in FIGS. 1, 3 to 5, the outer cylinder portion 31 includes an internal thread portion 311 that can be screwed with an external thread portion 251 formed on the outer periphery of the peripheral wall 25 of the container body 2. By screwing the internal thread portion 311 and the external thread portion 251, the cap 3 can be attached to the outer periphery of the opening 21 of the container body 2 (the outer periphery of the peripheral wall 25). The material of the outer cylinder portion 31 is not particularly limited as long as it can be attached to the outer periphery of the opening 21 of the container body 2 (specifically, the outer periphery of the peripheral wall 25), withstand the pressure (internal pressure) of carbon dioxide gas, and has sufficient strength as a cap. In the present embodiment, the outer cylinder portion 31 is made of, for example, a hard synthetic resin such as polypropylene or high-density polyethylene (HDPE).

[0020] As shown in Figures 1, 3, and 5, the inner cylinder portion 32 is integrally molded inside the outer cylinder portion 31. In this embodiment, the inner cylinder portion 32 is provided concentrically with respect to the outer cylinder portion 31 on the inside of the outer cylinder portion 31 in the radial direction D2. In this embodiment, the cap 3 has a gap S1 (see Figure 3) between the outer cylinder portion 31 and the inner cylinder portion 32. That is, the inner cylinder portion 32 is positioned on the inside of the outer cylinder portion 31 in the radial direction D2, with a gap S11 from the inner circumference of the outer cylinder portion 31. The gap S1 is the space into which the peripheral wall 25 that forms the opening 21 of the container body 2 is inserted. The size of the gap S1, i.e., the gap S11 between the outer cylinder portion 31 and the inner cylinder portion 32, is large enough to insert the peripheral wall 25. The gap S11 is also large enough to allow the female thread portion 311 of the outer cylinder portion 31 and the male thread portion 251 of the container body 2 to be screwed together. A gap S1 is provided between the outer cylinder portion 31 and the inner cylinder portion 32, allowing the female thread portion 311 and the male thread portion 251 to be screwed together with the peripheral wall 25 inserted into the gap S1. In the axial direction D1, the length of the inner cylinder portion 32 is such that when the plug member 4 is held by the holding portion 323 (described later), the plug member 4 fits inside the cap 3. This allows the inner cylinder portion 32 to hold the plug member 4 so that when the plug member 4 is held by the holding portion 323, the plug member 4 fits inside the cap 3. In the examples shown in Figures 1, 3, and 5, in the axial direction D1, the inner cylinder portion 32 is shorter than the length of the outer cylinder portion 31, and is approximately half the length of the outer cylinder portion 31. This allows the inner cylinder portion 32 to hold the plug member 4 so that the plug member 4 fits inside the cap 3.

[0021] The inner cylinder portion 32 is made of an elastic material. In the examples shown in Figures 1, 3, and 5, a part of the inner cylinder portion 32 (the sealing portion 322 including the holding portion 323 described later) is made of an elastic material. In this specification, "elastic material" means a material that has an elastic force such that the inner cylinder portion 32 can elastically hold the stopper member 4, and the stopper member 4 is inserted into the inner cylinder portion 32 against the elastic force of the inner cylinder portion 32 when subjected to the pressure of carbon dioxide gas. The type of elastic material is not particularly limited as long as it has such elastic force. Examples of elastic materials include low-density polyethylene (LDPE), soft synthetic resins such as silicone, or elastomers.

[0022] In this embodiment, the other part of the inner cylinder portion 32 (the folded portion 321 described later) is made of a hard material. Also, in this embodiment, the outer cylinder portion 31 and the folded portion 321 of the inner cylinder portion 32 are integrally made of the same hard material. The folded portion 321 of the inner cylinder portion 32 is a cylindrical portion that is folded back to the rearward side inward in the radial direction D2 from the front end of the outer cylinder portion 31 (the front end of the beverage container 1) and extends in the rearward direction. In the axial direction D1, the rear end of the folded portion 321 is located in front of the central part of the outer cylinder portion 31 (upper side in Figures 1, 3 and 5).

[0023] The sealing portion 322 of the inner cylinder portion 32 is a cylindrical portion that extends in the rear direction (downward in Figures 1, 3, and 5) from the rear end of the folded portion 321 (lower end in Figures 1, 3, and 5). This sealing portion 322 includes a portion that holds the spherical stopper member 4 (hereinafter referred to as the holding portion 323). The sealing portion 322 is made of a different material (elastic material, for example, a soft elastic material) than the folded portion 321 and the outer cylinder portion 31. The folded portion 321 and the sealing portion 322 are formed integrally. In this embodiment, the folded portion 321 and the sealing portion 322 are formed integrally by two-color molding. The sealing portion 322 includes the holding portion 323 and the opposing portion 324.

[0024] The inner cylinder portion 32 has a cylindrical holding portion 323 (see Figures 1, 3 to 5) into which the stopper member 4 is inserted from the end on the container body 2 side in the axial direction D1 (the lower end in Figures 1 and 5), thereby elastically holding the stopper member 4. In this embodiment, the sealing portion 322 of the inner cylinder portion 32 has the holding portion 323. The holding portion 323 is made of the elastic material described above. The holding portion 323 is configured such that the stopper member 4, which is subjected to the pressure of carbon dioxide gas inside the container body 2, is inserted into the holding portion 323 against the elastic force of the holding portion 323 due to that pressure. In this embodiment, the holding portion 323 has an insertion opening 32a (see Figures 1 and 5) for the stopper member 4. The insertion opening 32a is an opening into which the stopper member 4 is inserted. The insertion opening 32a is also an opening from which the stopper member 4 inserted into the holding portion 323 is discharged. The diameter L1 of the insertion opening 32a is smaller than the diameter L2 of the stopper member 4. Specifically, the diameter L1 of the insertion opening 32a in its natural state (see Figures 4 and 5) is smaller than the diameter L2 of the stopper member 4 (see Figure 1). The holding portion 323 is configured such that, with the stopper member 4 in contact with the inner periphery of the insertion opening 32a, the stopper member 4 receives pressure from the carbon dioxide gas contained in the carbonated beverage inside the container body 2, causing the insertion opening 32a to be elastically expanded and the stopper member 4 to be inserted into the holding portion 323 (see Figure 1). In this embodiment, the holding portion 323 is configured such that when the beverage container 1, which contains a beverage containing carbon dioxide and a stopper member 4 in the container body 2 and has a cap 3 screwed onto the container body 2, is inverted upside down so that the opening 33 is on the lower side, the stopper member 4 falls down to a position where it contacts the inner periphery of the insertion opening 32a, and the insertion opening 32a is elastically pushed open by the stopper member 4, which is under pressure from the carbon dioxide, the stopper member 4 is inserted into the holding portion 323 (see Figure 1).

[0025] The gripping portion 323 has a projection 32b that seals the space between the gripping portion 323 and the stopper member 4 by elastically contacting the surface of the stopper member 4 while the stopper member 4 is being held. In this specification, "elastically contacting" means that the projection 32b contacts the surface of the stopper member 4 so as to be pressed against the surface of the stopper member 4, causing the projection 32b to be elastically deformed so as to be crushed (so as the height of the projection 32b decreases), and the projection 32b and the surface of the stopper member 4 to be in close contact. Furthermore, the projection 32b is an annular projection provided along the circumferential direction on the inner circumference of the gripping portion 323 (see Figures 3 to 5). When such annular projection 32b is in close contact with the surface of the stopper member 4, the space in front of the projection 32b (upper side in Figure 1) and the space behind the projection 32b (lower side in Figure 1) are blocked by the projection 32b. Therefore, the projection 32b can seal the space between the inner surface of the gripping portion 323 and the surface of the stopper member 4. Furthermore, the cap 3 can improve the airtightness between the cap 3 and the stopper member 4 compared to the case where the projection 32b is absent. This enhances the effect of suppressing the leakage of carbon dioxide gas from inside the beverage container 1 to the outside.

[0026] The number of protrusions 32b is not particularly limited; there may be one or more. In this embodiment, multiple protrusions 32b are provided. In the example shown in Figures 3 to 5, multiple protrusions 32b are arranged in the axial direction D1 of the gripping portion 323. By arranging the multiple protrusions 32b in the axial direction D1, the multiple protrusions 32b make close contact with the surface of the stopper member 4, thereby further improving the airtightness between the cap 3 and the stopper member 4. Furthermore, by arranging the multiple protrusions 32b in the axial direction D1, even if the diameter of the stopper member 4 is changed, any of the protrusions 32b (one or more protrusions) can make close contact with the stopper member 4. Therefore, it is possible to use stopper members 4 with different diameters.

[0027] Furthermore, in the example shown in Figure 4, the tips of each of the multiple protrusions 32b are aligned in their natural state to follow a curved surface (a virtual curved surface) with approximately the same curvature as the surface of the stopper member 4. Specifically, the tips of each of the multiple protrusions 32b are aligned on a curved surface (a virtual curved surface) with approximately the same curvature as the surface of the stopper member 4. As a result, the multiple protrusions 32b adhere to the surface of the stopper member 4 with greater precision, thereby further improving the airtightness between the cap 3 and the stopper member 4.

[0028] Furthermore, the cross-sectional shape of the projection 32b is not particularly limited, as long as it can adhere closely to the stopper member 4 and seal the space between them. In the examples shown in Figures 4 and 6, the cross-sectional shape of the projection 32b when cut along the axial direction D1 is arc-shaped or semi-circular. In this case, when the projection 32b is pressed against the stopper member 4 and elastically deformed, the projection 32b is flattened or nearly flattened, ensuring a sufficient contact area between the deformed projection 32b and the stopper member 4. Therefore, the airtightness between the cap 3 and the stopper member 4 can be further improved. Also, if the cross-sectional shape of the projection 32b is arc-shaped or semi-circular, the cap 3 can be easily manufactured by injection molding. Specifically, if the cross-sectional shape of the projection 32b is arc-shaped or semi-circular, the projection 32b can be easily removed from the mold of the injection molding machine, thus making it easy to manufacture the cap 3. Note that the cross-sectional shape of the projection 32b when cut along the axial direction D1 is not limited to arc-shaped or semi-circular, and may be other shapes. For example, the cross-sectional shape of the projection 32b may be triangular or the like.

[0029] The gripping portion 323 has an insertion-direction-side support portion 32c that supports the region 41 (hereinafter also referred to as the insertion-side region 41; see Figure 7) on the outer surface of the stopper member 4, on the side of the stopper member 4 that is in the insertion direction D3 (see Figures 1, 4, and 5) from the center of the stopper member 4. In this embodiment, the insertion direction D3 of the stopper member 4 is forward, and is the direction from the rear of the gripping portion 323 towards the gripping portion 323. When inserting the stopper member 4 into the gripping portion 323, the beverage container 1 is inverted upside down so that the opening 33 of the cap 3 faces downward. This is because inverting the beverage container 1 from a state where the stopper member 4 is resting on the constricted portion 22 allows the stopper member 4 to fall to the insertion opening 32a of the gripping portion 323 by gravity. The insertion of the stopper member 4 into the holding portion 323 is performed by applying carbon dioxide pressure to the stopper member 4 while the stopper member 4 is resting on the periphery of the insertion opening 32a of the holding portion 323. Therefore, the insertion direction D3 is downward (direction of gravity).

[0030] The insertion-side region 41 of the stopper member 4 (see Figures 1 and 7) is the area of ​​the surface of the stopper member 4 that is pressed against the holding portion 323 by the pressure of carbon dioxide. In this embodiment, the stopper member 4 is pressed from the rear to the front by carbon dioxide. Therefore, the portion of the surface of the stopper member 4 that is in front of the center of the stopper member 4 is pressed against the holding portion 323 by the pressure of carbon dioxide. Thus, the portion of the surface of the stopper member 4 that is in front of the center of the stopper member 4 is the insertion-side region 41.

[0031] The insertion-direction-side support portion 32c elastically supports the insertion-side region 41 of the stopper member 4. Because the insertion-side region 41 of the stopper member 4 is supported by the insertion-direction-side support portion 32c, the stopper member 4 can efficiently transmit the pressure received from carbon dioxide to the insertion-direction-side support portion 32c. In this embodiment, the insertion-direction-side support portion 32c is formed to conform to the insertion-side region 41 of the stopper member 4 when the stopper member 4 is inserted into the holding portion 323. Furthermore, the insertion-direction-side support portion 32c has an inner surface with approximately the same curvature as the surface curvature of the insertion-side region 41. This allows the stopper member 4 to transmit the pressure received from carbon dioxide to the insertion-direction-side support portion 32c even more efficiently. The projection 32b is provided on the insertion-direction-side support portion 32c. Because the projection 32b is provided on the insertion-direction-side support portion 32c, the stopper member 4 can efficiently transmit the pressure received from carbon dioxide to the projection 32b. Therefore, the projection 32b is elastically deformed into a flat shape by the pressure received from the stopper member 4, and adheres tightly to the insertion-side region 41 on the surface of the stopper member 4. This allows the cap 3 to improve the airtightness between the holding portion 323 and the stopper member 4.

[0032] Furthermore, in this embodiment, the holding portion 323 has a discharge-side support portion 32d that supports the region 42 on the surface of the plug member 4 that is opposite to the insertion direction D3 of the plug member 4 from the center of the plug member 4 (hereinafter also referred to as the discharge-side region 42; see Figures 1 and 7). In this embodiment, the direction opposite to the insertion direction D3 of the plug member 4 is the rear direction, which is the direction in which the plug member 4 is discharged from the holding portion 323. In this embodiment, the portion of the surface of the plug member 4 that is rearward from the center of the plug member 4 is the discharge-side region 42.

[0033] The discharge-direction-side support portion 32d elastically supports the discharge-side region 42 of the plug member 4. By elastically supporting the discharge-side region 42 of the plug member 4, the discharge-direction-side support portion 32d can efficiently transmit forward elastic force to the discharge-side region 42 of the plug member 4. In this embodiment, the discharge-direction-side support portion 32d is formed to conform to the surface of the discharge-side region 42 when the plug member 4 is inserted into the holding portion 323. In this case, the discharge-direction-side support portion 32d can transmit forward elastic force to the discharge-side region 42 of the plug member 4 even more efficiently. Therefore, the discharge-direction-side support portion 32d can prevent the plug member 4 from falling out of the holding portion 323.

[0034] Furthermore, the rear end of the holding portion 323, specifically the rear end of the discharge-direction support portion 32d, has a cross-section along the axial direction D1 that is arc-shaped (see Figure 4). This allows the plug member 4 to be smoothly inserted into the holding portion 323. Therefore, when inserting the plug member 4 into the holding portion 323, it is possible to prevent the rear end of the holding portion 323 from being dragged by the plug member 4 and becoming entangled in the inside of the holding portion 323.

[0035] In this embodiment, the inner cylinder portion 32 has an opposing portion 324 that faces the inner circumference of the opening 21 of the container body 2 with a gap S2 (see Figure 6) when the stopper member 4 is not inserted into the holding portion 323 (see Figures 1, 5 to 7). The opposing portion 324 has the function of positioning the inner cylinder portion 32 relative to the container body 2 when the cap 3 is attached to the container body 2, and the function of sealing the space between the cap 3 and the container body 2 by being pushed outwards radially (expanded in diameter) when the stopper member 4 is inserted into the inner cylinder portion 32. The form of the opposing portion 324 is not particularly limited as long as it has the positioning function and sealing function described above. In the example shown in Figures 1, 3 to 5, the opposing portion 324 is formed integrally with the cylindrical holding portion 323 at the front part of the holding portion 323 (upper part in Figures 1, 3 to 7) so as to protrude radially outward in the direction D2 from the outer circumference of the holding portion 323. Furthermore, the opposing portion 324 is formed concentrically with respect to the holding portion 323. In addition, the opposing portion 324 is formed in a shape and size that can be accommodated in the aforementioned notch portion 252 of the container body 2. Specifically, the opposing portion 324 has an annular supported surface 32e (see Figure 4) that contacts the annular support surface 253 of the notch portion 252, and a cylindrical supported surface 32f (see Figure 4) that faces the cylindrical support surface 254 of the notch portion 252 before expansion and contacts the cylindrical support surface 254 after expansion.

[0036] The opposing portion 324 is expanded radially D2 by the insertion of the stopper member 4 into the holding portion 323 (see Figure 7), thereby increasing the outer diameter of the opposing portion 324. This causes it to elastically contact the inner circumference of the opening 21 of the container body 2, sealing the space between the inner circumference of the opening 21 of the container body 2 and the opposing portion 324. In this embodiment, as shown in Figure 6, the outer diameter of the opposing portion 324 is smaller than the inner diameter of the opening 21 of the container body 2 (specifically, the inner diameter of the cylindrical support surface 254 in the peripheral wall 25) in its natural state. Therefore, when attaching the cap 3 to the container body 2, a gap S2 is formed between the outer circumference of the opposing portion 324 (cylindrical supported surface 32f) and the inner circumference of the opening 21 of the container body 2 (the inner circumference of the cylindrical support surface 254 in the peripheral wall 25). This allows the opposing portion 324 to be easily inserted into the notch 252 in the container body 2. Therefore, the inner cylinder portion 32 of the cap 3 can be easily inserted into the opening 21 of the container body 2, and the cap 3 can be easily attached to the container body 2.

[0037] The specific configuration of the opposing portion 324 is not particularly limited, as long as it is expanded radially D2 when the stopper member 4 is inserted into the holding portion 323, elastically contacts the inner circumference of the opening 21 of the container body 2, and can seal the space between the inner circumference of the opening 21 of the container body 2 and the opposing portion 324. In this embodiment, the position of the opposing portion 324 relative to the projection 32b is set such that the pressing force received by the holding portion 323 from the stopper member 4 via the projection 32b expands the diameter of the opposing portion 324. Specifically, for example, the opposing portion 324 is positioned such that the component of the pressure received by the stopper member 4 from carbon dioxide gas and transmitted to the projection 32b, which is directed toward the opposing portion 324, expands the diameter of the opposing portion 324. For example, at the contact position between the stopper member 4 and the projection 32b, the opposing portion 324 is provided in a direction perpendicular to the surface of the stopper member 4. Therefore, a portion of the pressure received by the stopper member 4 from the carbon dioxide is converted into a force that expands the diameter of the opposing portion 324, causing the opposing portion 324 to expand in diameter. As a result, the opposing portion 324 adheres tightly to the inner circumferential surface of the container body 2, sealing the space between the opposing portion 324 and the container body 2.

[0038] The stopper member 4 is a spherical member that is inserted into the holding portion 323 under the pressure of carbon dioxide gas and closes the opening 33 of the cap 3. The form of the stopper member 4 is not particularly limited as long as it can be held by the holding portion 323 and close the opening 33 of the cap 3. In this embodiment, for example, it has a diameter larger than the inner diameter of the insertion opening 32a of the holding portion 323 in its natural state. Also in this embodiment, the stopper member 4 is made of a material that allows it to quickly fall to the insertion opening 32a of the holding portion 323 when the stopper member 4 and the beverage container 1 containing the beverage are turned upside down. Glass is one example of such a material.

[0039] Next, the method for sealing the beverage container 1 will be explained with reference to Figures 1 to 3 and Figures 5 to 7. First, as shown in Figure 2, the stopper member 4 and the beverage such as ramune are placed inside the container body 2. This places the stopper member 4 on the constricted portion 22. Next, as shown in Figures 3, 5, and 6, the cap 3 is attached to the container body 2 by screwing the female threaded portion 311 of the cap 3 into the male threaded portion 251 formed on the outer circumference of the opening 21 of the container body 2. Next, the beverage container 1 is inverted so that the opening 33 faces downwards. This causes the stopper member 4 to fall to the insertion opening 32a of the holding portion 323 and come into contact with the inner periphery of the insertion opening 32a. The stopper member 4, under the pressure of the carbon dioxide gas in the beverage, pushes open the insertion opening 32a and is inserted into the holding portion 323 (see Figures 1 and 7). Within the holding portion 323, the stopper member 4 is pressed against the projection 32b by the pressure received from the carbon dioxide gas. The projection 32b elastically deforms so as to be crushed by the pressure received from the stopper member 4 (see Figure 7). As a result, the projection 32b adheres tightly to the surface of the stopper member 4. Therefore, the space between the opening 33 of the cap 3 and the stopper member 4 is sealed. In addition, the opposing portion 324 expands in diameter due to the pressure received from the stopper member 4 via the projection 32b and adheres tightly to the inner circumference of the container body 2 (see Figure 7). As a result, the space between the cap 3 and the container body 2 is sealed. With these steps, the opening 21 of the beverage container 1 is sealed. [Explanation of symbols]

[0040] 1 beverage container 2. Container body 21 Opening 22 Stenosis 23 Upper part 24 Lower part 25 Peripheral wall 251 Male threaded section 252 Notch 253 Annular support surface 254 Cylindrical support surface 3 caps 31 Outer cylinder 311 Female thread section 32 Inner cylinder 321 Folded section 322 Seal part 323 Holding part 324 Opposing part 32a Insertion port 32b protrusion 32c Insertion direction side support part 32d Ejection direction side support part 32e Annular supported surface 32f Cylindrical supported surface 33 Opening 4. Spherical stopper member 41 Insertion side region 42 Discharge side area D1 Axial direction D2 radial direction S1 Gap between the outer cylinder and the inner cylinder S11 Distance between the outer cylinder and the inner cylinder S2 Gap between the inner circumference of the opening of the container body and the opposing part

Claims

1. A cylindrical cap that is attached to the outer circumference of the opening of a bottle-shaped container body, and the opening of the cap is sealed by a spherical stopper member, for use as a beverage container. An outer cylinder portion attached to the outer circumference of the opening of the container body, The outer cylindrical portion is integrally molded with an inner cylindrical portion made of an elastic material, and the inner cylindrical portion is integrally molded with the inner cylindrical portion. The inner cylinder portion has a cylindrical holding portion into which the stopper member is inserted from the end on the container body side in the axial direction, thereby elastically holding the stopper member. The holding portion has a projection that seals the space between the holding portion and the stopper member by elastically contacting the surface of the stopper member while holding the stopper member. The aforementioned projection is an annular projection provided along the circumferential direction on the inner circumference of the holding portion, in a cap for a beverage container.

2. The holding portion has an insertion opening for the stopper member, The diameter of the insertion opening is smaller than the diameter of the stopper member. The cap for a beverage container according to claim 1, wherein the stopper member is in contact with the inner periphery of the insertion opening, and the stopper member is subjected to the pressure of carbon dioxide gas contained in the carbonated beverage inside the container body, causing the insertion opening to be elastically expanded and the stopper member to be inserted into the holding portion.

3. The holding portion has an insertion-direction-side support portion that supports the region of the outer surface of the stopper member that is on the insertion-direction side of the stopper member, from the center of the stopper member. The cap for a beverage container according to claim 1, wherein the projection is provided on the support portion on the insertion direction side.

4. The beverage container cap according to claim 1, wherein a plurality of the aforementioned protrusions are arranged in the axial direction of the holding portion.

5. The inner cylinder portion has an opposing portion that faces the inner circumference of the opening of the container body with a gap between it and the holding portion when the stopper member is not inserted into the holding portion. The beverage container cap according to claim 1, wherein the opposing portion is expanded radially when the stopper member is inserted into the holding portion, thereby increasing the outer diameter of the opposing portion, and thereby elastically contacting the inner circumference of the opening of the container body, and sealing the space between the inner circumference of the opening of the container body and the opposing portion.

6. A beverage container comprising a bottle-shaped container body and a beverage container cap according to claim 1, which is attached to the outer circumference of the opening of the container body.

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