JP7332613B2 - 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 cap body having a top wall (top plate) and a skirt wall (skirt-shaped side wall) descending from the peripheral edge thereof, and a middle leg that is in close contact with the inner surface of the container opening on the inner surface of the top wall. (Inner ring) and an outer leg (outer ring) in close contact with the outer surface of the mouth of the container are known (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.

JP 2015-9853 A

However, in the above-described conventional cap, as shown in FIG. 3(A), the fold-back portion 50 extending from the upper end of the skirt wall to the base of the outer leg on the inner surface of the cap body is relatively angular in longitudinal cross-section, so stress is applied. There is a problem that cracks are likely to occur due to concentration of It should be noted that such cracks also lead to deterioration of the sealing performance of the container.

Therefore, as shown in FIG. 3(B), it is conceivable to form the vertical cross-sectional view of the folded portion 50 into an arc shape having a constant radius of curvature. There is a risk that measures will be insufficient in terms of prevention.

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above problems, and an object thereof is to provide a synthetic resin cap that is effective in preventing cracking and that 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. and, on the lower surface of the top wall, integrally formed an annular middle leg that closely contacts the inner peripheral surface of the container mouth and an annular outer leg that closely contacts the outer peripheral surface of the container mouth. In a certain synthetic resin cap, the inner peripheral surface of the skirt wall has a folded portion that curves from the upper side and connects to the outer peripheral surface of the outer leg, and a vertical cross-sectional shape that has an arc shape with an inner diameter increasing toward the lower side. An inclined portion and a straight portion having a constant inner diameter are provided. The inclined portion has a larger vertical width than the folded portion, and the outer peripheral surface of the outer leg is curved from above to form the skirt. The skirt wall has a folded portion connected to the inner peripheral surface of the wall, and an inclined portion that has a smaller inner diameter toward the bottom and occupies most of the outer peripheral surface , and the folded portion of the skirt wall and the folded portion of the outer leg is formed in a continuous state so as to be positioned on the same circumference when viewed in vertical cross section, and has a radius of curvature smaller than the radius of curvature of the sloped portion of the skirt wall when viewed in vertical cross section, and the outer circumference of the top wall. The top surface of the top wall is curved so as to become lower toward the outside, and the top surface of the center portion of the top wall extends flat from the inner peripheral end of the outer peripheral portion toward the center of the top surface, and is located on the lower surface of the top wall. The boundary between the two folded portions is positioned below the portion connecting to the inner side of the foot, the portion connecting to the inner side of the outer leg on the lower surface of the top wall is located at a position corresponding to the central portion, and the boundary is the above-mentioned boundary. It is located at a position corresponding to the outer periphery (claim 1).

In the above synthetic resin cap, the inner peripheral surface of the outer leg may expand downward, and the inclination angle of the inner peripheral surface of the outer leg with respect to the vertical plane may be 10° to 16° (claim Item 2).

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

That is, in the synthetic resin cap of the invention according to each claim of the present application, since the thickness of the portion of the skirt wall connected to the outer leg is increased, the occurrence of cracks when stress is applied can be effectively prevented. be able to.

In the synthetic resin cap according to the second aspect of the invention, it is easy to improve the sealing performance by increasing the thickness in the vicinity of the base of the outer leg.

(A) is a bottom view schematically showing the configuration of a synthetic resin cap according to one embodiment of the present invention, and (B) is a cutaway view taken along line AA of (A). It is a BB line cutaway view of FIG. 1(A). (A) to (C) are explanatory diagrams showing a comparison between a conventional example and a synthetic resin cap of the present invention.

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

1(A), (B), and 2, a synthetic resin cap (hereinafter referred to as a cap) 1 is used by being attached to the mouth portion M (see FIG. 2) of a container such as a PET bottle. and are integrally molded of polyethylene by compression molding or injection molding. 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. 1A and 1B, the cap 1 includes a substantially circular ceiling wall 2 in plan view and a substantially cylindrical skirt wall 3 extending downward from the outer periphery of the ceiling wall 2. have. Here, the outer peripheral surface of the skirt wall 3 is provided with a knurled groove 4, and the inner peripheral surface thereof is provided with a female thread 5. The female thread 5 is coupled to the male thread M1 (see FIG. 2) formed on the outer periphery of the container mouth. (screwed) is possible.

Then, when the cap 1 is rotated so that the female thread 5 of the skirt wall 3 is coupled to the male thread M1 of the container mouth M and attached to the container mouth M, an annular ring connected to the inner surface (lower surface) of the top wall 2 is formed. A middle leg (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 M, thereby sealing the mouth of the container (see FIG. 3). That is, as shown by the phantom lines in FIG. 2, when the cap 1 is attached to the mouth portion M of the container, the middle leg 6 is inserted into the mouth portion M of the container and comes into close contact with the inner peripheral surface of the mouth portion M of the container. , the annular rib 7 is in close contact with the annular upper end surface of the container opening M, and the outer leg 8 is in close contact with the outer peripheral surface of the container opening M. As shown in FIG.

In addition, the cap 1 is a pilfer proof cap that has a function to prove that it is unopened (that it has never been opened), and when the unopened cap 1 attached to the container mouth M is opened (first ), when the cap 1 is rotated so that the connection between the male screw M1 and the female screw 5 is released, the cap 1 is separated from the container mouth M, but the tamper evidence connected to the lower part of the skirt wall 3 A band (hereinafter simply referred to as a “band”) 9 is configured to remain on the mouth portion M 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 extending along the entire circumference of the skirt wall 3 (see FIG. 3). 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 vertically. A portion (peripheral portion) of the bridge 10a is also cut by the slit 10b so that the bridge 10a is broken when pulled with a predetermined force.

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) M2 formed below the male thread M1 on the outer circumference of the container mouth M when the cap 1 is attached to the container mouth M. Then, it is locked to the annular projection M2 by the unplugging operation (see FIG. 3). That is, the locking piece 11 is configured to be able to be locked to the annular projection M2 from below, and when the cap main body (the skirt wall 3 and the top wall 2) above the annular weakened portion 10 is opened, the opening of the container is closed. Detached from M, the band 9 below the annular weakened portion 10 remains in the container mouth portion M, and the annular weakened portion 10 is broken along with this.

Here, the band 9 is integrally formed with the cap main body (the skirt wall 3 and the top wall 2), and the locking piece 11 provided on the band 9 protrudes upward as shown in FIG.

In this embodiment, as shown in the enlarged view of FIG. 2, the inner peripheral surface of the skirt wall 3 is composed of, from the upper side, a folded portion 12 that curves and connects to the outer peripheral surface of the outer leg 8, and the inner diameter increases toward the lower side. and a straight portion 14 with a constant inner diameter. Specifically, the vertical width of the folded portion 12 is 0.05 mm to 0.3 mm, and the vertical width of the inclined portion 13 is 0.5 mm to 2.0 mm.

Further, as shown in the enlarged view of FIG. 2, the outer peripheral surface of the outer leg 8 includes a folded portion 15 that curves from the upper side and connects to the inner peripheral surface of the skirt wall 3, and an inclined portion that decreases in inner diameter toward the lower side. The folded portion 12 of the skirt wall 3 and the folded portion 15 of the outer leg 8 are configured to be positioned on the same circumference in a vertical cross-sectional view, and the radius of curvature thereof is the same as that of the skirt wall 3. It is smaller than the radius of curvature of the inclined portion 13 when viewed in longitudinal section. In this example, the radius of curvature of the folded portions 12 and 15 when viewed in longitudinal section is 0.1 mm, and the radius of curvature of the inclined portion 13 when viewed in longitudinal section is 3 mm.

With such a configuration, in the cap 1 of the present embodiment, the thickness of the portion of the skirt wall 3 connected to the outer leg 8 is increased, so cracks can be effectively prevented from occurring when stress is applied. can be done. That is, FIG. 3(C) shows the main part of the cap 1 of this embodiment, and the dashed line in this figure indicates the skirt wall 3 in FIG. 3(B). In the example of FIG. 4B, the folded portion 50 extending from the skirt wall 3 to the outer leg 8 is curved so as to be positioned on the same circumference in a vertical cross-sectional view. Since the inclined portion 13 is not provided in the skirt wall 3, the radius of curvature of the folded portion 50 is increased, and the thickness of the portion of the skirt wall 3 connected to the outer leg 8 is reduced accordingly. On the other hand, in the cap 1 of this embodiment provided with the inclined portion 13, as shown in FIG. When curved so as to be positioned upward, the regions occupied by the folded portions 12 and 15 are narrowed, and the skirt wall 3 is thickened by the amount of the inclined portion 13 provided between the straight portion 14 and the folded portion 12. Become.

In addition, the inner peripheral surface of the outer leg 8 expands downward, and its gradient θ (see the enlarged view in FIG. 2) is 10° or more, preferably 12° to 16°. With such a configuration, it becomes easy to increase the thickness of the base portion of the outer leg 8 to improve the sealing performance. Furthermore, this effect is obtained by positioning the boundary between the folded portion 15 of the outer leg 8 and the folded portion 12 of the skirt wall 3 below the portion between the outer leg 8 and the annular rib 6 on the lower surface of the top wall 2, This is reinforced by making it difficult for the outer leg 8 to fall outward. Moreover, this improvement in sealing performance is achieved by increasing the thickness of the portion of the top wall 2 that is closer to the outer periphery than the portion that is closer to the inner periphery of the middle leg 6 (especially the portion of the top wall 2 between the middle leg 6 and the outer leg 8). It is also enhanced by

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.

For example, in the above-described embodiment, the vertical cross-sectional shape of the inclined portion 13 is arc-shaped, but the shape is not limited to this. It may have an inclined shape. That is, the inclined portion 13 is not located on the same circumference as the folded portions 12 and 15 in a vertical cross-sectional view, but has a gentler slope than the folded portion 12 and extends downward over a wider range than the folded portion 12. It is sufficient if the diameter is expanded.

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 foot 7 annular rib 8 outer foot 9 tamper evidence band 10 annular weakened portion 10a bridge 10b slit 11 locking piece 12 folded portion 13 inclined portion 14 straight portion 15 Folded portion 16 Inclined portion 50 Folded portion M Container opening M1 External thread M2 Annular projection θ Gradient

Claims (2)

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 into the male thread of the container mouth. A synthetic resin cap integrally formed with an annular middle leg that is in close contact with the surface and an annular outer leg that is in close contact with the outer peripheral surface of the container opening,
The inner peripheral surface of the skirt wall includes, from the upper side, a folded portion that curves and connects to the outer peripheral surface of the outer leg, an inclined portion that has an arcuate vertical cross-sectional shape with an inner diameter that increases toward the lower side, and a constant inner diameter. and a straight portion, and the inclined portion has a larger vertical width than the folded portion,
The outer peripheral surface of the outer leg has, from the upper side, a folded portion that curves and connects to the inner peripheral surface of the skirt wall, and an inclined portion that decreases in inner diameter toward the lower side and occupies most of the outer peripheral surface. ,
The folded portion of the skirt wall and the folded portion of the outer leg are connected to each other so as to be positioned on the same circumference in a vertical cross-sectional view, and the curvature radius thereof is the same as that of the inclined portion of the skirt wall. smaller than the radius of curvature in longitudinal section,
The top surface of the outer peripheral portion of the top wall is curved so as to become lower toward the outside, and the top surface of the central portion of the top wall extends flat from the inner peripheral end of the outer peripheral portion toward the center of the top surface,
Positioning the boundaries of the two folded portions below the portion that continues to the inside of the outer leg on the lower surface of the ceiling wall,
A synthetic resin cap, wherein a portion of the lower surface of the ceiling wall that continues to the inner side of the outer leg is located at a position corresponding to the central portion, and the boundary is located at a position corresponding to the outer peripheral portion. 2. The synthetic resin cap according to claim 1, wherein the inner peripheral surface of said outer leg expands downward, and the inclination angle of said inner peripheral surface of said outer leg with respect to a vertical plane is 10° to 16°.