JP7195091B2 - Synthetic resin cap - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a synthetic resin cap that is attached to the mouth of a container that holds contents such as beverages.

As a conventional synthetic resin cap, it has a top wall (top wall) and a skirt wall hanging down from the periphery thereof, and on the inner surface of the top wall, a middle leg (inner sealing piece) that is in close contact with the inner surface of the container mouth, and a container mouth. An outer leg (outer seal piece) that is in close contact with the outer surface of the portion is known (for example, Patent Document 1).

In such a cap, the inner and outer legs are in close contact with the inner and outer surfaces of the mouth of the container, thereby ensuring the sealing of the inside of the container.

Japanese Patent No. 5291175

However, although the cause is not clear, cracks may occur in conventional caps attached to beverage containers in stores, vending machines, etc., and cracks occur particularly in the ceiling wall. The tendency to be recognized is remarkable.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a synthetic resin cap which is effective in preventing cracks in the top wall and which can improve sealing performance.

In order to achieve the above object, the synthetic resin cap according to the present invention comprises a top wall, and a skirt wall extending downward from the outer peripheral portion of the top wall and having a female thread to be screwed to the male thread of the container opening. The thickness of the central portion of the top wall is larger than the thickness of the periphery thereof, and the bottom surface of the top wall has the inner periphery of the container opening An annular middle leg is provided in close contact with the surface, and a rib projecting downward is provided between the central portion and the middle leg on the lower surface of the ceiling wall, and the rib is connected to the central portion. The central portion protrudes downward from the ribs, the lower surface of the central portion protrudes downward in a substantially dome shape, and the ribs are connected to the lower surface of the central portion. The rib is composed of an eight-sided portion surrounding the central portion and forming sides of a substantially regular octagon concentric with the central portion, and a sum of the eight-sided portions. It has a connection portion extending inwardly from four vertices that are not adjacent to each other among the eight vertices and connected to the central portion, and a projecting portion extending outward from the eight vertices (Claim 1). ).

The present invention provides a synthetic resin cap that is effective in preventing cracking of the top wall and that can improve sealing performance.

That is, in the synthetic resin cap of the invention according to each claim of the present application, by increasing the thickness of the central portion of the top wall, it is possible to effectively prevent cracks in the top wall, and as a result, the sealing performance is improved. can be obtained.

In the synthetic resin cap of the first aspect of the invention, the ribs provided around the central portion further enhance the above effect.

1 is a bottom view schematically showing the configuration of a synthetic resin cap according to one embodiment of the present invention; FIG. FIG. 2 is a cutaway view taken along line AA of FIG. 1;

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 FIGS. 1 and 2 is used by being attached to the mouth of a container such as a PET bottle. is molded into The material for forming the cap 1 is not particularly limited, and in addition to the polyethylene used in the present embodiment, polypropylene or the like is preferably used.

As shown in FIGS. 1 and 2, the cap 1 has a substantially circular top wall 2 in plan view and a substantially cylindrical skirt wall 3 extending downward from the outer periphery of the top wall 2. there is Here, the skirt wall 3 has a knurled groove 4 on its outer peripheral surface and a female thread 5 on its inner peripheral surface. be.

Then, when the cap 1 is rotated so that the female thread 5 of the skirt wall 3 is connected to the male thread of the container mouth and attached to the mouth of the container, an annular middle leg ( An inner ring 6, an annular rib 7 and an annular outer leg (outer ring) 8 are brought into close contact with the mouth of the container, thereby sealing the mouth of the container. That is, when the cap 1 is attached to the mouth of the container, the middle leg 6 is inserted into the mouth of the container and adheres closely to the inner peripheral surface of the mouth of the container, and the annular rib 7 is attached to the annular upper end surface of the mouth of the container. The outer leg 8 is configured to be in close contact with the outer peripheral surface of the container mouth.

In addition, the cap 1 is a pilfer proof cap that has a function to prove that it is unopened (that the cap has never been opened), and when the unopened cap 1 attached to the mouth of the container is opened (first When the cap 1 is rotated so that the connection between the male thread and the female thread 5 is released when the cap is opened), the cap 1 separates from the mouth of the container, but the tamper evidence band (hereinafter referred to as , simply called "band") 9 is configured to remain on the mouth of the container.

That is, the band 9 is connected to the lower portion of the skirt wall 3 via an annular weakened portion 10 that extends along the entire circumference of the skirt wall 3 , and the annular weakened portion 10 extends inside the boundary between the skirt wall 3 and the band 9 . It is composed of a plurality of bridges 10a present on the circumferential side and slits 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 vertically. A portion (peripheral portion) of the bridge 10a is also cut with a slit 10b so that it will break when pulled.

In addition, on the inner peripheral side of the band 9, a plurality of (eight in this example) locking pieces (flaps) 11 protruding inward are provided at intervals in the circumferential direction (see FIGS. 1 and 2). ). Each locking piece 11 is positioned substantially below an annular projection (bead portion) formed below the male thread on the outer periphery of the container mouth when the cap 1 is attached to the container mouth. It locks into the annular projection by manipulation (see FIG. 3). That is, the locking piece 11 is configured so as to be able to be locked to the annular projection from below, and when the cap main body (skirt wall 3 and top wall 2) above the annular weakened portion 10 is opened from the opening of the container. The band 9 which is separated and located below the annular weakened portion 10 remains at the mouth of the container, and the annular weakened portion 10 is broken along with this.

Here, the band 9 is formed integrally with the cap main body (skirt wall 3 and top wall 2), and locking pieces 11 provided on the band 9 protrude downward as shown in FIG. 2 when the cap 1 is formed. However, when the cap 1 is attached to the mouth of the container, it is pushed up by the annular projection and turned over to protrude upward.

In this embodiment, as shown in FIGS. 1 and 2, the lower surface of the central portion 12 of the top wall 2 is bulged downward in a substantially dome shape, and the thickness of the central portion 12 is equal to the thickness of the surrounding area. is set to be larger than

More specifically, the central portion 12 of the top wall 2 is positioned at the center of a substantially circular area 13 surrounded by the middle legs 6 when viewed from the bottom, and the center of the area 13 and the center of the central portion 12 coincide with each other when viewed from the bottom. . Here, the inner diameter of the base of the middle foot 6 (the diameter of the region 13) can be 18 mm to 35 mm, and it is conceivable that it is, for example, about 20 mm (20.2 mm as an example).

Further, a rib 14 protruding downward is provided on the lower surface of the ceiling wall 2, and the thickness of a portion of the ceiling wall 2 where the rib 14 or the like is not provided (nothing is provided) is 0.7 mm. is provided is 1.0 mm (that is, the maximum height of the rib 14 is 0.3 mm), whereas the maximum thickness of the central portion 12 (thickness at the center) is 1.2 mm. 2.4 mm (preferably 1.3 mm to 1.8 mm). That is, the central portion 12 protrudes downward from the ribs 14, and if the maximum thickness of the central portion 12 is less than 1.2 mm, cracks are likely to occur in the ceiling wall 2. decreases.

The lower surface of the central portion 12 is part of a spherical surface with a radius of 2 mm to 7 mm, and the maximum outer diameter of the central portion 12 in bottom view is 3 mm to 7 mm. In this example, since the ribs 14 are provided, part of the lower surface of the central portion 12 is missing and does not have a circular shape when viewed from the bottom.

Thus, in the cap 1 of the present embodiment, by increasing the thickness of the central portion 12 of the top wall 2, it is possible to effectively prevent the top wall 2 from cracking, and thus improve the sealing performance. becomes possible. This effect is enhanced by the ribs 14 provided around the central portion 12 .

It goes without saying that the present invention is not limited to the above-described embodiments, and can be modified in various ways without departing from the gist of the present invention. For example, the following modifications can be given.

In the above-described embodiment, the central portion 12 is made to bulge downward by utilizing the fact that a gate reservoir is normally formed in the center of the ceiling wall 2 when the cap 1 is injection molded. The cap 1 may be molded by other molding methods such as compression molding as long as it is possible to form the central portion 12 thicker than the portion of . Further, when thickening the central portion 12 of the top wall 2, the lower surface of the central portion 12 is not limited to being raised downward, and for example, the upper surface of the central portion 12 may be raised upward.

Although the rib 14 is provided at the position connected to the central portion 12 in the above embodiment, the rib 14 may not be provided at the position connected to the central portion 12, for example. That is, on the lower surface of the ceiling wall 2, the ribs 14 may be provided with a space around the central portion 12, and the middle legs 6 may be provided so as to surround the ribs 14.

It goes without saying that the modifications described in this specification may be combined as appropriate.

1 synthetic resin cap 2 top wall 3 skirt wall 4 knurled groove 5 female screw 6 middle leg 7 annular rib 8 outer leg 9 tamper evidence band 10 annular weakened portion 10a bridge 10b slit 11 locking piece 12 central portion 13 region 14 rib

Claims (1)

A synthetic resin cap comprising a top wall and a skirt wall extending downward from the outer periphery of the top wall and having a female thread to be screwed to a male thread of a container opening,
The thickness of the central portion of the ceiling wall is greater than the thickness of its surroundings,
An annular middle leg is provided on the lower surface of the ceiling wall and is in close contact with the inner peripheral surface of the container mouth,
Further, a rib projecting downward is provided between the central portion and the middle leg on the lower surface of the top wall,
The rib is provided at a position connected to the central portion,
The central portion protrudes downward from the rib,
The lower surface of the central portion is bulged downward in a substantially dome shape, and the entire portion of the lower surface of the central portion to which the ribs are not connected is configured to be a part of the spherical surface,
The ribs extend inward from eight sides that surround the central part and form sides of a substantially regular octagon concentric with the central part, and four vertices that are not adjacent to each other among a total of eight vertices of the eight sides. A synthetic resin cap characterized by having a connecting portion extending from the central portion and connecting to the central portion, and projecting portions extending outward from the eight vertexes .

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