Container with cap and cap

Abstract

To provide a container with a cap which suppresses lowering of sealability caused by inner pressure increase of the container with a cap, and to provide a cap.SOLUTION: In a container with a cap 10, an outer ring 34 includes: an upper side region 35 which has upper side seal parts 35a, 35b coming into contact with a line unformed region 61a in a cap mounted state; and a lower side extension region 36 which has a lower side additional seal part 36a arranged by having a gap on an outer peripheral side of a line formed region 61b in a cap mounted state. The upper side seal part 35a is formed being curved so as to be a convex shape toward the inner peripheral side. The lower side additional seal part 36a mounts the cap, and by deforming in such a manner that a top surface wall 31 swells in a dome-like shape caused by internal pressure increase in the container, in a state where the outer ring 34 moves to the upper side and the upper side seal parts 35a, 35b are separated from a container mouth cylindrical part 61, a lower end part of the outer ring 34 comes into contact with the line unformed region 61a so as to be closer to the inner peripheral side.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a container with a cap and the cap, and more particularly to a container with a cap and a cap used in applications where the inside of the container is under positive pressure.

Background Art

[0002] Conventionally, as a container with a cap for storing beverages and the like, in a state where the cap is attached to the container, an outer ring formed to protrude downward from the top surface wall of the cap is brought into close contact with the container mouth cylindrical portion, thereby sealing between the container mouth cylindrical portion and the outer ring and maintaining the airtightness of the container with a cap (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In such a container with a cap, when the container with a cap is stored at a high temperature with a carbonated beverage stored inside, or when the internal pressure of the container with a cap becomes positive pressure, the top surface wall of the cap may be deformed so as to bulge in a dome shape due to the increase in the internal pressure. Depending on the degree of deformation of this top surface wall, the outer ring may move upward with respect to the container mouth cylindrical portion and separate from the container mouth cylindrical portion, resulting in a problem that the airtightness of the container with a cap may decrease.

[0005] As a measure to suppress the decrease in the airtightness of the container with a cap as described above, it is conceivable to suppress the deformation of the top surface wall itself by selecting the wall thickness and material of the top surface wall. However, depending on the content liquid and storage conditions of the container with a cap, it is difficult to prevent the curvature of the top surface wall, and there is also a problem that the design freedom regarding the size and material of the cap is impaired.

[0006] Therefore, the present invention aims to solve these problems and provides a container with a cap and a cap that have a simple structure and suppress a decrease in airtightness caused by an increase in the internal pressure of the container with a cap.

Means for Solving the Problems

[0007] The container with a cap of the present invention is a container with a cap including a container having a container mouth cylindrical portion and a cap attached to the container mouth cylindrical portion, wherein the container mouth cylindrical portion has an unformed line region where a parting line is not formed on its outer peripheral surface and a formed line region which is a region below the unformed line region and has a parting line formed on its outer peripheral surface, the cap includes a top wall and an outer ring formed to protrude downward from the top wall and disposed on the outer peripheral side of the container mouth cylindrical portion in a cap-attached state where the cap is attached to the container mouth cylindrical portion, and the outer ring has an upper side region having an upper side seal portion that contacts the unformed line region in the cap-attached state and a lower side extended region formed below the upper side region and having a lower side additional seal portion disposed with a gap on the outer peripheral side of the formed line region in the cap-attached state. Well, the upper seal part is formed to be curved so as to be convex toward the inner peripheral side. The lower side additional seal portion is formed so as to contact the unformed line region when the cap is attached to the container mouth cylindrical portion and Due to the increase in the internal pressure of the container, the top wall is deformed so as to bulge in a dome shape. in a state where the outer ring moves upward with respect to the container mouth cylindrical portion and the upper side seal portion is separated from the container mouth cylindrical portion. The lower end part of the outer ring moves closer to the inner peripheral side. This solves the above problems. The cap of the present invention is a cap that is attached to a container mouth cylinder portion having a line-unformed region on its outer peripheral surface where a parting line is not formed and a line-formed region below the line-unformed region where a parting line is formed on its outer peripheral surface. The cap includes a top wall and an outer ring that protrudes downward from the top wall and is disposed on the outer peripheral side of the container mouth cylinder portion in a cap-attached state where the cap is attached to the container mouth cylinder portion. The outer ring has an upper region having an upper sealing portion that contacts the line-unformed region in the cap-attached state, and a lower extension region formed below the upper region and having a lower additional sealing portion that is disposed with a gap on the outer peripheral side of the line-formed region in the cap-attached state. Well, the upper seal part is formed to be curved so as to be convex toward the inner peripheral side. The lower additional sealing portion is formed so as to contact the line-unformed region when the cap is attached to the container mouth cylinder portion and Due to the increase in the internal pressure of the container, the top wall is deformed so as to bulge in a dome shape. in a state where the outer ring moves upward with respect to the container mouth cylinder portion and the upper sealing portion is separated from the container mouth cylinder portion. The lower end part of the outer ring moves closer to the inner peripheral side. By being formed in this way, the above problems are solved.

Advantages of the Invention

[0008] According to the present invention, the outer ring of the cap has an upper region having an upper sealing portion that contacts the line-unformed region in a cap-attached state where the cap is attached to the container mouth cylinder portion, and a lower extension region formed below the upper region and having a lower additional sealing portion that is disposed with a gap on the outer peripheral side of the line-formed region in the cap-attached state. Well, the upper seal part is formed to be curved so as to be convex toward the inner peripheral side. The lower additional sealing portion is formed when the cap is attached to the container mouth cylinder portion and Due to the increase in the internal pressure of the container, the top wall is deformed so as to bulge in a dome shape. in a state where the outer ring moves upward with respect to the container mouth cylinder portion and the upper sealing portion is separated from the container mouth cylinder portion. The lower end part of the outer ring moves closer to the inner peripheral side. It is formed so as to contact the line-unformed area. By doing so, while avoiding contact of the outer ring with the line-formed area of the container mouth cylinder part where the parting line is formed as a trace of the mating surface of the mold, it is possible to avoid the situation where contact of the outer ring with the line-formed area of the container mouth cylinder part inhibits contact of the upper sealing part with the line-unformed area of the container mouth cylinder part. Even when the outer ring moves upward with respect to the container mouth cylinder part due to an increase in the internal pressure of the container, it is possible to maintain the seal between the container mouth cylinder part and the outer ring by bringing the lower additional sealing part into contact with the line-unformed area of the container mouth cylinder part. Therefore, with a simple configuration, it is possible to suppress a decrease in airtightness due to an increase in the internal pressure of the capped container.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Embodiments for Carrying Out the Invention

[0010] Hereinafter, the capped container 10 according to the first embodiment of the present invention will be described with reference to the drawings.

[0011] As shown in FIG. 2, the container 10 with a cap includes a synthetic resin container 60 having a container mouth cylindrical portion 61, and a synthetic resin cap 20 attached to the container mouth cylindrical portion 61.

[0012] As shown in FIG. 1, the cap 20 includes a cap body 30 and a TE band 40 connected to the lower end of the cap body 30 via a weakened portion 50.

[0013] As shown in FIGS. 1 and 2, the cap body 30 has a disc-shaped top wall 31 and a cylindrical skirt wall 32 hanging down from the outer peripheral edge of the top wall 31.

[0014] As shown in FIGS. 1 and 2, an inner ring 33 protruding downward from the lower surface of the top wall 31 and an outer ring 34 protruding downward from the lower surface of the top wall 31 on the outer peripheral side of the inner ring 33 are formed on the top wall 31.

[0015] As shown in FIG. 1, a knurl portion (serration groove) 32a is formed on the outer peripheral wall of the skirt wall 32, and a cap-side screw portion 32b that engages with a container-side screw portion 62 formed on the outer peripheral wall of the container mouth cylindrical portion 61 of the container 60 is formed on the inner peripheral wall of the skirt wall 32.

[0016] As shown in FIG. 2, in a cap-attached state where the cap 20 is attached to the container mouth cylindrical portion 61 (a state where the cap-side screw portion 32b is screwed into the container-side screw portion 62 and the cap 20 is engaged with the container mouth cylindrical portion 61 to the lowermost side), the inner ring 33 is in close contact with the inner peripheral side of the container mouth cylindrical portion 61 over the entire circumference in the circumferential direction of the cap at a position lower than the close contact portion of the outer ring 34 with respect to the container mouth cylindrical portion 61, and seals between the container mouth cylindrical portion 61 and the cap 20. Note that this inner ring 33 is formed so as to contact the inner peripheral surface of the container mouth cylindrical portion 61 in any of the states shown in FIGS. 2 to 4 described later.

[0017] As shown in FIG. 2, in the state where the cap is attached, the outer ring 34 is in close contact with the outer peripheral side of the container mouth cylinder portion 61 over the entire circumference in the circumferential direction of the cap, and seals the space between the container mouth cylinder portion 61 and the cap 20. The outer ring 34 has the same cross-sectional shape over the entire circumference in the circumferential direction of the cap.

[0018] As shown in FIG. 2, in the state where the cap is attached, the outer ring 34 has an upper region 35 located on the outer peripheral side of the unformed line region 61a of the container mouth cylinder portion 61 to be described later, and a lower extension region 36 that is continuously formed below the upper region 35 and is located on the outer peripheral side of the formed line region 61b of the container mouth cylinder portion 61 to be described later.

[0019] As shown in FIG. 2, in the state where the cap is attached, the upper region 35 has upper sealing portions 35a and 35b that come into contact (adhere) with the unformed line region 61a of the container mouth cylinder portion 61 over the entire circumference in the circumferential direction of the cap to seal the space between the container mouth cylinder portion 61 and the outer ring 34. In the first embodiment, it has a first upper sealing portion 35a and a second upper sealing portion 35b.

[0020] As shown in FIG. 2, the first upper sealing portion 35a is formed to be curved convexly toward the inner peripheral side and is formed to contact the outer peripheral surface of the unformed line region 61a in the state where the cap is attached. As shown in FIG. 2, the second upper sealing portion 35b is formed in a flat surface shape inclined so as to approach the inner peripheral side as it goes upward above the first upper sealing portion 35a, and is formed to contact an inclined portion (shoulder portion) formed between the upper end portion and the outer peripheral portion of the container mouth cylinder portion 61 in the state where the cap is attached. This second upper sealing portion 35b is formed to be inclined so that the angle with respect to the axial direction (vertical direction) of the cap 20 is 40 to 50° (more preferably 42 to 48°). As shown in FIG. 2, the inner peripheral surface of the first upper sealing portion 35a and the inner peripheral surface of the second upper sealing portion 35b are smoothly connected by a connecting surface formed to be curved concavely toward the outer peripheral side.

[0021] As shown in FIG. 2, the lower-side extension region 36 has a lower-side additional seal portion 36a that is arranged with a gap on the outer peripheral side of the line formation region 61b of the container mouth cylindrical portion 61 (in other words, it does not contact the outer peripheral surface of the line formation region 61b including the parting line 63) in the cap-attached state. In the present embodiment, as shown in FIG. 2, the inner peripheral surface of the lower-side additional seal portion 36a is formed such that its upper-side portion has a linear (or curved) cross-sectional shape (the cross-sectional shape when cut by a plane including the vertical direction as shown in FIG. 2), and its lower-side portion is formed as a portion curved so that the cross-sectional shape is convex toward the lower side and the inner peripheral side. The lower-side portion also functions as a corner between the lower end portion and the inner peripheral portion of the outer ring 34. Note that the specific form of the lower-side additional seal portion 36a is not limited to the above, and the cross-sectional shape of its inner peripheral surface may be any shape, such as a curved shape, a linear shape, or a combination of curves and lines.

[0022] As shown in FIG. 2, the lower-side additional seal portion 36a is located at a position separated from the outer peripheral surface of the line formation region 61b of the container mouth cylindrical portion 61 during normal times (when the top surface wall 31 is not elastically deformed into a dome shape due to an increase in the internal pressure in the container 60, and the upper-side seal portions 35a and 35b of the upper-side region 35 are in contact with the container mouth cylindrical portion 61). However, as shown in FIG. 4, when the top surface wall 31 bulges into a dome shape due to an increase in the pressure in the container 60, the outer ring 34 moves upward with respect to the container mouth cylindrical portion 61, and the upper-side seal portions 35a and 35b are separated from the container mouth cylindrical portion 61, the lower-side additional seal portion 36a contacts (adheres) to the non-line-formed region 61a of the container mouth cylindrical portion 61 over the entire circumference in the cap circumferential direction to seal the space between the container mouth cylindrical portion 61 and the outer ring 34.

[0023] Also, as shown in FIG. 2, the entire inner peripheral surface of the lower-side extension region 36 is formed to be inclined so as to approach the outer diameter side as it goes downward. Thus, by forming the inner peripheral surface of the lower-side extension region 36 to be inclined, the mold release during the injection molding of the cap 20 becomes easier, that is, the cap 20 after injection molding can be easily removed from a mold (not shown) disposed on the inner peripheral side of the outer ring 34 during injection molding. Note that the specific aspect of the lower-side extension region 36 may be any aspect such that the cross-sectional shape of its inner peripheral surface (the cross-sectional shape when cut by a plane including the vertical direction as shown in FIG. 2) is curved, linear, or a combination of a curve and a line.

[0024] As shown in FIG. 2, the inner peripheral surface of the outer ring 34 is formed to be curved so as to be concave on the outer diameter side, and further has a connecting inner peripheral surface 37 that connects the inner peripheral surface of the first upper-side seal portion 35a and the inner peripheral surface of the lower-side additional seal portion 36a in the vertical direction. Since the connecting inner peripheral surface 37 is formed to be curved so as to smoothly connect the inner peripheral surface of the first upper-side seal portion 35a and the inner peripheral surface of the lower-side additional seal portion 36a, the occurrence of cracks in the outer ring 34 can be suppressed. Due to this connecting inner peripheral surface 37, it is possible to smoothly transition from the state of FIG. 3 where the first upper-side seal portion 35a contacts the container mouth cylindrical portion 61 to the state of FIG. 4 where the lower-side additional seal portion 36a contacts the container mouth cylindrical portion 61 with respect to the container mouth cylindrical portion 61. Note that the connecting inner peripheral surface 37 may be formed such that its cross-sectional shape (the cross-sectional shape when cut by a plane including the vertical direction as shown in FIG. 2) is linear.

[0025] As shown in FIG. 1, the TE band 40 has an annular band main body portion 41 and a flap 42 that is continuously provided at the lower end of the band main body portion 41 and folded back upward on the inner peripheral side of the band main body portion 41 and can be engaged with a container flange (not shown) from below in the cap-attached state. A plurality of flaps 42 are formed along the circumferential direction of the cap with an interval therebetween.

[0026] As shown in FIG. 1, the weakening portion 50 is a breakable annular portion that connects the lower end of the skirt wall 32 of the cap body 30 and the upper end of the band main body portion 41 of the TE band 40. In the present embodiment, the weakening portion 50 is composed of a plurality of bridges and slits formed alternately in the circumferential direction of the cap. Note that the specific form of the weakening portion 50 may be any as long as it is provided to be breakable.

[0027] A parting line 63 is formed on the outer peripheral surface of the container 60. This parting line 63 is formed as a trace of the mating surface of the mold used to mold the container 60, and is formed due to misalignment between the molds on the mating surface. Specific forms of the parting line 63 include, as shown in FIG. 9(a), a stepped one extending along the vertical direction (axial direction of the container 60), as shown in FIGS. 9(a) and 9(b), a stepped one extending along the circumferential direction of the container mouth cylindrical portion 61, and, not shown, a protruding (burr) one protruding outward from the outer peripheral surface of the container 60 extending along the vertical direction (axial direction of the container 60), etc. In FIGS. 9(a) and 9(b), the step of the parting line 63 is shown greatly exaggerated. In addition, in the present embodiment, the container 60 is formed by blow molding a preform (not shown) which is a preformed body, and the parting line 63 of the present embodiment is formed at the stage of injection molding the preform (not shown) using a mold.

[0028] As shown in FIG. 2, the container mouth cylindrical portion 61 has an upper end side line non-formation region 61a where the parting line 63 is not formed on its outer peripheral surface, and a lower side line formation region 61b which is a region below the line non-formation region 61a and where the parting line 63 is formed on its outer peripheral surface.

[0029] Next, the contact state of the outer ring 34 with respect to the container mouth cylindrical portion 61 in the present embodiment will be described below with reference to FIGS. 2 to 4.

[0030] First, as shown in FIG. 2, in the normal state with the cap attached (when the top wall 31 is not elastically deformed into a dome shape due to the increase in the internal pressure in the container 60), the first upper seal portion 35a and the second upper seal portion 35b are in contact with the non-line-formed region 61a of the container mouth cylindrical portion 61. Also, the lower additional seal portion 36a is disposed at a position separated from the outer peripheral surface of the line-formed region 61b of the container mouth cylindrical portion 61. Here, if the lower additional seal portion 36a contacts in a form that straddles the non-line-formed region 61a and the line-formed region 61b, or in a form that contacts only the line-formed region 61b, there is a risk of leakage from the slight gap due to the above-described burr (parting line 63).

[0031] Next, as shown in FIG. 3, when the top wall 31 is elastically deformed into a dome shape due to the increase in the internal pressure in the container 60 with the cap 20 attached to the container mouth cylindrical portion 61, the outer ring 34 moves upward with respect to the container mouth cylindrical portion 61. First, the second upper seal portion 35b separates from the container mouth cylindrical portion 61. Here, when the top wall 31 is elastically deformed into a dome shape, as shown in FIGS. 3 and 4, as the central portion side of the top wall 31 moves more upward than the outer peripheral portion side, the outer ring 34 (and the inner ring 33) tilts such that its lower end portion approaches the inner peripheral side compared to the normal state shown in FIG. 2. Also, in the state shown in FIG. 3, the lower additional seal portion 36a still remains separated from the outer peripheral surface of the line-formed region 61b of the container mouth cylindrical portion 61.

[0032] Next, as shown in FIG. 4, when the internal pressure of the container 60 further increases from the state shown in FIG. 3 and the outer ring 34 moves further upward with respect to the container mouth cylindrical portion 61, the first upper seal portion 35a separates from the container mouth cylindrical portion 61, and the lower additional seal portion 36a contacts the line-formed region 61b of the container mouth cylindrical portion 61.

[0033] Here, in the present embodiment, from the state where the first upper seal portion 35a is in contact with the container mouth cylindrical portion 61 shown in FIG. 3, it transitions to a state where both the first upper seal portion 35a and the lower additional seal portion 36a are in contact with the container mouth cylindrical portion 61, and then transitions to a state where the lower additional seal portion 36a is in contact with the container mouth cylindrical portion 61 shown in FIG. 4. However, from the state where the first upper seal portion 35a is in contact with the container mouth cylindrical portion 61 shown in FIG. 3, it may be configured to transition to a state where neither the first upper seal portion 35a nor the lower additional seal portion 36a is in contact with the container mouth cylindrical portion 61, and then transition to a state where the lower additional seal portion 36a is in contact with the container mouth cylindrical portion 61 shown in FIG. 4. Also, it may be configured such that the first upper seal portion 35a separates from the container mouth cylindrical portion 61 and simultaneously the lower additional seal portion 36a comes into contact with the container mouth cylindrical portion 61. Note that in the above description, the focus was on the contact states of the first upper seal portion 35a and the lower additional seal portion 36a with the container mouth cylindrical portion 61. Regarding the connection inner peripheral surface 37 formed between the first upper seal portion 35a and the lower additional seal portion 36a, the connection inner peripheral surface 37 may be configured to come into contact with the container mouth cylindrical portion 61 at an arbitrary timing, or may be configured not to come into contact with the container mouth cylindrical portion 61.

[0034] Next, the capped container 10 according to the second embodiment of the present invention will be described with reference to FIGS. 5 to 8. Here, in the second embodiment, except for some configurations, it is exactly the same as the first embodiment described above. Therefore, the description of the configurations other than the differences will be omitted.

[0035] First, in the first embodiment described above, the upper region 35 of the outer ring 34 was described as having the first upper seal portion 35a and the second upper seal portion 35b as the upper seal portion that contacts the container mouth cylindrical portion 61, as shown in FIG. 2. In contrast, in the second embodiment, the second upper seal portion 35b is not provided on the outer ring 34. Instead, as shown in FIG. 6, a third seal portion 38 is formed to protrude downward from the top wall 31 between the inner ring 33 and the outer ring 34, and in the state where the cap is attached, it is in close contact with the upper end surface of the container mouth cylinder portion 61 to seal the space between the top wall 31 and the container mouth cylinder portion 61 over the entire circumference in the circumferential direction of the cap.

[0036] In such a second embodiment, as shown in FIG. 7, when the top wall 31 elastically deforms into a dome shape due to an increase in the internal pressure in the container 60 in the state where the cap 20 is attached to the container mouth cylinder portion 61, the third seal portion 38 separates from the container mouth cylinder portion 61 before the second upper seal portion 35b separates from the container mouth cylinder portion 61.

[0037] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above embodiments, and various design changes can be made without departing from the present invention described in the claims.

[0038] For example, in the above-described embodiment, the cap 20 has been described as including the cap body 30 and the TE band 40 connected to the lower end of the cap body 30 via the weakening portion 50. However, the specific form of the cap 20 may be any form as long as it has the outer ring 34.

Explanation of Reference Numerals

[0039] 10 ··· Container with cap 20 ··· Cap 30 ··· Cap body 31 ··· Top wall 32 ··· Skirt wall 32a ··· Narl portion 32b ··· Cap-side screw portion 33 ··· Inner ring 34 ··· Outer ring 35 ··· Upper region 35a ··· First upper seal part 35b ··· Second upper seal part 36 ··· Lower extension region 36a ··· Lower additional seal part 37 ··· Connecting inner peripheral surface 38 ··· Third seal part 40 ··· TE band 41 ··· Band main body part 42 ··· Flap 50 ··· Weakening part 60 ··· Container 61 ··· Container mouth cylinder part 61a ··· Line non-formed region 61b ··· Line formed region 62 ··· Container side screw part 63 ··· Partition line

Claims

1. A container with a cap, comprising a container having a container mouth cylindrical portion and a cap attached to the container mouth cylindrical portion, wherein the container mouth cylindrical portion has a line-unformed region where a parting line is not formed on its outer peripheral surface, and a line-formed region which is a region below the line-unformed region and where a parting line is formed on its outer peripheral surface, the cap includes a top wall and an outer ring which protrudes downward from the top wall and is disposed on the outer peripheral side of the container mouth cylindrical portion in a cap-attached state where the cap is attached to the container mouth cylindrical portion, the outer ring has an upper-side region having an upper-side seal portion which contacts the line-unformed region in the cap-attached state, and a lower-side extended region formed below the upper-side region and having a lower-side additional seal portion which is disposed with a gap on the outer peripheral side of the line-formed region in the cap-attached state, the upper-side seal portion is formed to be curved so as to be convex toward the inner peripheral side, the lower-side additional seal portion is formed such that when the cap is attached to the container mouth cylindrical portion and the top wall is deformed to bulge in a dome shape due to an increase in the internal pressure of the container, the outer ring moves upward with respect to the container mouth cylindrical portion and the upper-side seal portion is separated from the container mouth cylindrical portion, and the lower end portion of the outer ring contacts the line-unformed region so as to approach the inner peripheral side. A container with a cap characterized by this.

2. The container with a cap according to claim 1, wherein the inner peripheral surface of the lower-side additional seal portion has a portion curved so as to be convex toward the lower side and the inner peripheral side.

3. The container with a cap according to claim 1 or claim 2, wherein the inner peripheral surface of the outer ring has a connecting inner peripheral surface which is formed to be concave on the outer diameter side and connects the inner peripheral surface of the upper-side seal portion and the inner peripheral surface of the lower-side additional seal portion.

4. The container with a cap according to any one of claims 1 to 3, wherein the inner peripheral surface of the lower-side extended region is formed to be inclined so as to approach the outer diameter side as it goes downward.

5. A cap that is attached to a container mouth cylinder portion having a line-unformed region on its outer peripheral surface where a parting line is not formed and a region below the line-unformed region where a parting line is formed on its outer peripheral surface. The cap includes a top wall and an outer ring that protrudes downward from the top wall and is disposed on the outer peripheral side of the container mouth cylinder portion in a cap-attached state where the cap is attached to the container mouth cylinder portion. The outer ring includes an upper region having an upper seal portion that contacts the line-unformed region in the cap-attached state, and a lower extension region formed below the upper region and having a lower additional seal portion that is disposed with a gap on the outer peripheral side of the line-formed region in the cap-attached state. The upper seal portion is formed to be curved so as to be convex toward the inner peripheral side. The lower additional seal portion is formed such that when the cap is attached to the container mouth cylinder portion and the top wall is deformed to bulge in a dome shape due to an increase in the internal pressure of the container, the outer ring moves upward with respect to the container mouth cylinder portion and the upper seal portion is separated from the container mouth cylinder portion, and the lower end portion of the outer ring contacts the line-unformed region so as to approach the inner peripheral side.

Images