CN113423648A

CN113423648A - Synthetic resin cap

Info

Publication number: CN113423648A
Application number: CN202080013708.4A
Authority: CN
Inventors: 黑岩靖文; 川村伸生; 见城广则; 小野淳史; 梅木慎吾
Original assignee: Nihon Yamamura Glass Co Ltd
Current assignee: Nihon Yamamura Glass Co Ltd
Priority date: 2019-03-07
Filing date: 2020-02-27
Publication date: 2021-09-21
Anticipated expiration: 2040-02-27
Also published as: KR20210129117A; JP7434275B2; CN113423648B; WO2020179607A1; JPWO2020179607A1

Abstract

The invention provides a synthetic resin cap capable of improving sealing performance. A synthetic resin cap (1) is provided with a top wall (2) and a skirt wall (3), wherein the skirt wall (3) extends downward from the outer periphery of the top wall (2), has an internal thread (5) screwed with an external thread (M1) of a container opening (M), and is integrally formed with an annular center leg (6) which is in close contact with the inner periphery of the container opening (M) on the lower surface of the top wall (2), wherein the longitudinal cross-sectional shape of the outer periphery of an upper portion (13) extending from a root portion (12) of the center leg (6) to a central portion (14) is a curved shape recessed inward of the center leg (6).

Description

Synthetic resin cap

Technical Field

The present invention relates to a synthetic resin cap which is attached to a mouth portion of a container for storing contents such as beverages, for example.

Background

As a conventional synthetic resin cap, there is known a synthetic resin cap as shown in fig. 3(a) and (B), which is configured to: an annular inner seal projection 53 fitted into the container mouth portion M, an annular opening end seal projection 54 abutting against an opening end face of the container mouth portion M, and an annular outer seal projection 55 abutting against an outer surface of the container mouth portion M are formed on the top plate portion 51 of the cap including the top plate portion 51 and a tube portion 52 hanging from a peripheral edge thereof, and the inner seal projection 53 abuts against the inner surface of the container mouth portion M in a state of being elastically bent slightly inward (patent document 1).

In the above-described synthetic resin cap, the inner sealing projection 53 abuts against the inner surface of the container mouth portion M with a sufficient pressing force.

Documents of the prior art

Patent document

Patent document 1: japanese patent No. 5977937

Disclosure of Invention

Problems to be solved by the invention

However, the conventional synthetic resin cap described above is considered to have room for improvement in sealing performance.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a synthetic resin cap which can improve sealing performance.

Means for solving the problems

In order to achieve the above object, a synthetic resin cap according to the present invention includes a top wall and a skirt wall extending downward from an outer peripheral portion of the top wall, the skirt wall having a female screw to be screwed with a male screw of a container mouth, and an annular center leg closely attached to an inner peripheral surface of the container mouth being integrally formed on a lower surface of the top wall, wherein a longitudinal sectional shape of an outer peripheral surface extending from a root portion of the center leg to an upper portion of the center leg is a curved shape recessed inward of the center leg (claim 1).

In the synthetic resin cap, the inner peripheral surface and the outer peripheral surface of the base portion of the center leg may have curved shapes that are respectively recessed upward of the center leg, and the inner peripheral surface may be gently curved compared to the outer peripheral surface of the base portion (claim 2).

In the synthetic resin cap, the outer peripheral surface of the base portion of the center leg may have a curved shape that is recessed upward of the center leg and is curved steeply compared with the longitudinal sectional shape of the inner edge of the front end of the container mouth (claim 3).

In the synthetic resin cap, an annular rib and an annular leg may be integrally formed on a lower surface of the top wall, the annular rib may be located on an outer peripheral side of the leg and may be in close contact with an upper end surface of the container mouth, the annular leg may be located on an outer peripheral side of the annular rib and may be in close contact with an outer peripheral surface of the container mouth, a seal point having a maximum outer diameter at a vertically central portion may be formed on the outer peripheral surface of the leg, and an axial distance from a lower end of the annular rib to the seal point of the leg may be 1.5mm or more and 3.5mm or less (claim 4).

Effects of the invention

The present invention provides a synthetic resin cap that can improve sealing properties.

That is, in the synthetic resin cap according to the present invention, when the container mouth is capped, the top outer peripheral surface of the cap, which is carefully studied, is likely to come into close contact with the inner edge of the front end of the container mouth, and accordingly, the sealing property can be improved.

In the synthetic resin caps according to the inventions of

claims

2 and 3, the above-described effect of improving the sealing performance can be improved by carefully devising the root shape of the midfoot portion.

In the synthetic resin cap according to the invention of claim 4, the sealing point of the midfoot is carefully examined to improve the prevention of the airtight leakage.

Drawings

Fig. 1(a) and (B) are a longitudinal sectional view and a main part enlarged explanatory view schematically showing the structure of a synthetic resin cap according to an embodiment of the present invention.

Fig. 2 is an explanatory view schematically showing a configuration of a main part of the synthetic resin cover.

Fig. 3(a) is a longitudinal sectional view showing a conventional synthetic resin cap, and (B) is a longitudinal sectional view showing a main portion thereof in an enlarged manner.

Detailed Description

Embodiments of the present invention will be described below with reference to the drawings.

A synthetic resin cap (hereinafter, referred to as a cap) 1 shown in fig. 1 a and 2 is used by being attached to a mouth M (see fig. 2) of a container such as a PET bottle and is integrally molded from polyethylene by compression molding or injection molding. The material for forming the cap 1 is not particularly limited, and polypropylene or the like is suitably used in addition to the polyethylene used in the present embodiment.

The cap 1 has a top wall 2 that is substantially circular in plan view, and a substantially cylindrical skirt wall 3 that extends downward from the outer periphery of the top wall 2. Here, the skirt wall 3 is provided with a knurled groove 4 on the outer peripheral surface and a female screw 5 on the inner peripheral surface, and the female screw 5 can be coupled to a male screw M1 (see fig. 2) formed on the outer periphery of the container mouth.

When the cap 1 is rotated and attached to the container mouth portion M so that the female screw 5 of the skirt wall 3 is coupled to the male screw M1 of the container mouth portion M, the annular center leg (inner ring) 6, the annular rib 7, and the annular outer leg (outer ring) 8, which are continuously provided on the inner surface (lower surface) of the top wall 2, come into close contact with the container mouth portion M, and the container mouth portion is thereby brought into a sealed state. That is, in a state where the cap 1 is attached to the container mouth M, the center leg 6 is inserted into the container mouth M and is in close contact with the inner peripheral surface of the container mouth M, the annular rib 7 is in close contact with the annular upper end surface of the container mouth M, and the outer leg 8 is in close contact with the outer peripheral surface of the container mouth M.

The cap 1 is a tamper-proof cap having a function of proving that it is not opened (not opened at a time), and is configured such that: when the unopened cap 1 attached to the container mouth portion M is unsealed (first opened), the cap 1 is rotated to release the engagement between the male screw M1 and the female screw 5, and the cap 1 is detached from the container mouth portion M, but a tamper evident band (hereinafter, simply referred to as "band") 9 connected to the lower portion of the skirt wall 3 remains in the container mouth portion M.

That is, the band 9 is connected to the lower portion of the skirt wall 3 by an annular weakened portion 10 extending along the entire circumference of the skirt wall 3, the annular weakened portion 10 is composed of a plurality of bridge portions 10a present on the inner circumferential side of the boundary between the skirt wall 3 and the band 9, and a slit 10b extending in the circumferential direction of the skirt wall 3 and the band 9 so as to divide the skirt wall 3 and the band 9 up and down, and a part (outer circumferential portion) of the bridge portions 10a is also cut by the slit 10b so that the bridge portions 10a are broken when stretched with a predetermined force.

Further, on the inner peripheral side of the belt 9, a plurality of (8 in this example) inwardly projecting locking pieces (flaps) 11 are provided at intervals in the circumferential direction. In a state where the cap 1 is attached to the container mouth portion M, each locking piece 11 is positioned slightly below an annular projection M2 (see fig. 2) formed below the male screw M1 on the outer periphery of the container mouth portion M, and is locked to the annular projection M2 by the unsealing operation. That is, the locking piece 11 is configured to be able to be locked to the annular projection M2 from below, and when unsealing, the lid main body portion (the skirt wall 3 and the top wall 2) above the annular weakened portion 10 is detached from the container mouth M, and the band 9 below the annular weakened portion 10 remains in the container mouth M, and the annular weakened portion 10 is broken along with this.

Here, the band 9 is integrally molded with the cap body portion (the skirt wall 3 and the top wall 2), and the locking piece 11 provided to the band 9 projects downward at the time of molding the cap 1, but is pushed up by the annular projection M2 to be inverted at the time of attaching the cap 1 to the container mouth portion M, and is in a state of projecting upward as shown in fig. 1(a) and 2.

In the present embodiment, as shown in fig. 1(B), the outer peripheral surface of the midfoot portion 6 is divided into four regions, i.e., an outer root portion 12, an outer upper portion 13, an outer central portion 14, and an outer lower portion 15, from the root side to the tip side in a longitudinal sectional view.

The outer root portion 12 has the following longitudinal sectional shape: the lower surface of the top wall 2 is curved so as to be recessed above the midfoot portion 6 with a certain radius of curvature from a position inside the annular rib 7. Further, the outer root portion 12 is curved from the upper end downward such that the outer diameter becomes smaller toward the lower side, but is curved at the lower portion such that the outer diameter becomes larger toward the lower side.

The outer upper portion 13 has the following longitudinal sectional shape: the lower end of the lateral root portion 12 is curved so as to be concave inward of the midfoot portion 6 with a certain radius of curvature.

The outer center portion 14 has the following longitudinal sectional shape: the lower end of the lateral upper portion 13 is curved so as to protrude (protrude) outward of the midfoot portion 6 with a certain radius of curvature. Further, a seal point 14a at which the outer diameter of the midfoot portion 6 is the largest is provided at the vertically central portion of the outer central portion 14, and the outer central portion 14 is curved from the upper end thereof to the seal point 14a so that the outer diameter becomes larger toward the lower side, but is curved from the seal point 14a to the lower side and conversely so that the outer diameter becomes smaller toward the lower side.

The outer lower portion 15 has the following longitudinal sectional shape: the outer center portion 14 extends linearly from the lower end thereof so as to have a constant inclination angle and have a smaller outer diameter toward the lower side.

In the present embodiment, as shown in fig. 1(B), the inner peripheral surface of the midfoot portion 6 is divided into two regions, an inner root portion 16 and an inner body portion 17, from the root side to the tip side in a longitudinal sectional view.

The inner root 16 has the following longitudinal sectional shape: the lower surface of the top wall 2 is curved so as to have a certain radius of curvature from a position on the inner side of the midfoot portion 6 and be concave upward of the midfoot portion 6. Further, the inner root 16 is curved from the upper end downward such that the inner diameter increases toward the lower side.

The inner body 17 has the following longitudinal sectional shape: the inner root 16 extends linearly from the lower end thereof so as to have a constant inclination angle (1 ° in this example) and to have an inner diameter that increases toward the lower side.

Here, in the longitudinal sectional shape of the midfoot portion 6, the radius of curvature of the inner root portion 16 is larger than the radius of curvature of the outer root portion 12 (the inner root portion 16 is curved more gently than the outer root portion 12), the radius of curvature of the outer center portion 14 is larger than the radius of curvature of the inner root portion 16, and the radius of curvature of the outer upper portion 13 is larger than the radius of curvature of the outer center portion 14. In the midfoot portion 6, the vertical width of the outer root portion 12 is greater than the vertical width of the inner root portion 16, the outer root portion 12 extends to a position below the inner root portion 16, the vertical width of the outer upper portion 13 is greater than the vertical width of the outer root portion 12, and the vertical width of the outer central portion 14 is smaller than the vertical width of the outer root portion 12 and the vertical width of the inner root portion 16.

In the center leg 6 configured as described above, since the longitudinal sectional shape of the outer upper portion 13, which is the largest area above the sealing point 14a on the outer peripheral surface thereof, is curved so as to be recessed inward of the center leg 6, the outer upper portion 13 is easily brought into close contact with the inner edge of the front end of the container mouth M when the cap 1 is attached to the container mouth M (when the cap is pressed), and the sealing property can be improved accordingly. Further, the effect is further enhanced by the following arrangement: no portion extending linearly in the vertical direction is provided on the upper portion of the outer peripheral surface of the center leg 6 (the upper side of the seal point 14 a), and a portion extending linearly (the inner body portion 17) is provided on the upper portion of the inner peripheral surface, that is, no portion extending in parallel inward and outward is provided on the upper portion of the center leg 6.

Further, the longitudinal sectional shapes of the outer root portion 12 and the inner root portion 16 of the center leg 6 are curved so as to be recessed above the center leg 6, and the inner root portion 16 is curved more gently than the outer root portion 12, whereby the above-described effect of improving the sealing property is also improved.

Here, the above-mentioned effect of improving the sealing property is also improved by, for example, making the longitudinal sectional shape of the outer root portion 12 smaller in curvature radius than the longitudinal sectional shape of the inner edge of the distal end of the container mouth portion M, so that the longitudinal sectional shape of the outer root portion 12 of the center leg 6 is curved more steeply than the longitudinal sectional shape of the inner edge of the distal end of the container mouth portion M.

The axial distance d1 from the lower end of the annular rib 7 to the seal point 14a of the midfoot 6 is preferably 1.5mm to 3.5 mm. If the diameter is less than 1.5mm, the sealing point 14a is too close to the tip of the container mouth M, whereas if the diameter exceeds 3.5mm, the portion above the sealing point 14a of the stem 6 is easily bent, and in any case, the airtight leakage is easily caused.

In the middle leg 6, the outer lower portion 15 is a portion which is brought into contact with the container mouth portion M at the time of capping, and basically, the central position 15a in the vertical direction is a portion which is supposed to be brought into contact with the container mouth portion M. In the present embodiment, the axial distance d2 from the seal point 14a to the center position 15a is greater in the center leg 6 than the axial distance d3 from the center position 15a to the lower end of the center leg 6, whereby the amount of material used can be reduced by downsizing the center leg 6, and the thickness of the lower portion of the center leg 6 can be increased to some extent so as to be hard to break. In the present embodiment, the center position 15a is located at a position (outer peripheral side) outside the minimum outer diameter position of the center leg 6 and is in a range not protruding to the outer peripheral side of the outer root 12, so that the center leg 6 is easily deformed in a wide range downward from the root thereof at the time of capping, stress is not concentrated, and resistance as large as this can be hardly received.

The present invention is not limited to the above embodiments, and it is needless to say that various modifications can be made without departing from the scope of the present invention. For example, the following modifications are possible.

In the above embodiment, the inner body 17 has the following longitudinal sectional shape: the inner base portion 16 extends linearly from the lower end thereof at a constant inclination angle (1 °) so that the inner diameter increases toward the lower side, thereby facilitating the mold release, but the inner body portion 17 may extend parallel to the axial direction of the cap 1.

In the example of fig. 1 a and 2, a flap 11 (configured to fold back the lower portion of the tape 9 inward) is provided, but instead of the flap 11, a hook (configured to provide a portion protruding toward the inner periphery of the tape 9) may be provided to engage with the annular projection M2 of the container mouth portion M.

In the example of fig. 1(a) and 2, the lower surface of the top wall 2 connected to the inner peripheral side of the midfoot portion 6 and the lower surface of the top wall 2 connected to the outer peripheral side are substantially the same height, but the lower surface of the top wall 2 is not limited thereto.

It is needless to say that the above modifications may be combined with each other as appropriate.

Description of the symbols

1 cover

2 roof wall

3 skirt wall

4 knurling groove

5 internal screw thread

6 middle foot

7 annular Rib

8 outer foot

9 tamper-evident band

10 annular weakened portion

11 locking piece

12 outer root part

13 outer upper part

14 outer central part

14a sealing point

15 outer lower part

16 inner root part

17 inner body part

51 ceiling part

52 barrel part

53 inner side sealing protrusion

54 open end sealing projection

55 outside sealing projection

d1 axial distance

d2 axial distance

d3 axial distance

M container mouth

M1 external thread

M2 Ring projection (engaged part)

Claims

1. A synthetic resin cap comprising a top wall and a skirt wall extending downward from an outer peripheral portion of the top wall and having a female screw to be screwed with a male screw of a container mouth, wherein an annular stem is integrally formed on a lower surface of the top wall so as to be in close contact with an inner peripheral surface of the container mouth,

the outer peripheral surface of the upper portion extending from the root portion to the central portion of the midfoot has a curved shape recessed inward of the midfoot in a longitudinal sectional shape.

2. The synthetic resin cap according to claim 1, wherein the inner peripheral surface and the outer peripheral surface of the base portion of the center leg have curved shapes in the longitudinal cross-sectional shape that are recessed upward of the center leg,

the inner peripheral surface is gently curved compared to the outer peripheral surface of the root portion.

3. The synthetic resin cap according to claim 1 or 2, wherein the outer peripheral surface of the base portion of the center leg has a curved shape that is recessed upward of the center leg and is curved steeply compared with the longitudinal sectional shape of the inner edge of the front end of the container mouth.

4. The synthetic resin cap according to any one of claims 1 to 3, wherein an annular rib and an annular leg are integrally formed on a lower surface of the top wall, the annular rib is located on an outer peripheral side of the center leg and is in close contact with an upper end surface of the container mouth, the annular leg is located on an outer peripheral side of the annular rib and is in close contact with an outer peripheral surface of the container mouth,

and a sealing point having the largest outer diameter at the central portion in the vertical direction is formed on the outer peripheral surface of the middle leg,

an axial distance from a lower end of the annular rib to the seal point of the midfoot is 1.5mm or more and 3.5mm or less.