Sealing cap

Abstract

The invention relates to a scaling cap (1) that is to be screwed and/or pressed onto the pouring neck (4) of a container, especially a bottle. Said sealing cap (1) comprises a particularly annular coaxial sealing lip (6) which is fixed within the bottom (2) of the cap and extends into the neck when the cap is mounted. The sealing lip is curved and/or buckled towards the outside between the upper and the lower end (7, 8) thereof in such a way that the curvature (12) and/or the buckled point (9) travel/s further out and the external face of the sealing lip sealingly rests against the interior wall of the neck when the sealing lip is compressed in an axial direction.

Description

The invention relates to a cap closure for screwing or pressing onto a pour neck of a container, in particular a bottle, comprising an in particular annular coaxial seal lip that is attached to the end wall of the cap and extends into the neck when, the cap is mounted.

For the cap closure of a plastic bottle, it is also known from DE 42 03 238 to mold onto the end wall of the cap an annular coaxial seal lip of C-section such and convex outward. In this manner an additional sealing point with the inner wall of the bottle neck is provided on the outer face of the seal lip. Although the seal is improved as a result, the sealing pressure at this additional sealing point is limited.

The object of the present invention is to improve a cap closure of the above-described type such that the additional annular seal lip achieves a high sealing pressure when the cap is mounted, in particular screwed on, so that the container withstands even high internal pressures.

This object is achieved according to the invention by the fact that the seal lip is outwardly curved and/or creased between the upper end and the lower end thereof in such a way that the curvature and/or the crease extends farther out and the outer face of the seal lip rests in a sealing manner against the inner wall of the neck when the seal lip is compressed axially.

Due to the compression of the seal lip axially, i.e. opposite the screwing direction, such a design produces a high contact pressure of the outer face of the seal lip against the inner wall of the neck in a radial direction, resulting in an extremely tight seal. The design is simple and functions reliably even when the cap is screwed on and off a number of times. In this manner the annular crease or annular outer region of the curvature seals with the inner wall of the neck.

It is particularly advantageous when the pour neck on its inner wall has at least one support surface against which the lower end of the seal lip abuts. In this manner the seal lip is reliably compressed, and the lower end of the seal lip also forms an additional seal with the support surface. The support surface is preferably annular. The support surface may also be formed by at least two projections on the inner wall of the pour neck.

A further alternative proposes that the seal lip has at least two creases. Improved movability of the seal lip at the attachment point to the cap end wall is achieved when the upper attachment point has a weakened region, in particular a strip of reduced thickness of the seal lip, between the seal lip and the cap end wall.

A precise, defined sealing surface, in particular a seal line, is achieved when the inner surface of the neck and/or the outer face of the seal lip have/has a raised location, in particular an annular bead, supporting the seal lip. The axial extension of the seal lip is preferably 30-100% of the height of the cap. The spacing of the support surface from the upper end of the neck should be less than the axial length of the seal lip.

Two illustrated embodiments of the invention are described below in greater detail, and are illustrated in the drawing in axial sections, as follows:

FIG. 1 shows a seal lip having an annular crease; and

FIG. 2 shows an outwardly curved seal lip.

A cap closure 1 manufactured by injection molding of plastic has an upper horizontal end wall 2 and a cylindrical side wall 3 that is molded in a downward direction onto the outer edge of the end wall. A tamper-indicating ring may also be molded onto the lower end of the side wall 3 so that it breaks off when the cap is opened. Such a cap 1 may be screwed or pressed onto a cylindrical pour neck 4 of a container, in particular a container neck such as for example a bottle. A screw thread 5 is preferably provided between an inner face of the side wall 3 and an outer face of the neck 4.

An internal annular seal lip 6 is molded coaxial to the cap axis onto an underside of the end wall 2, and extends downward and into the neck 4 when the cap is set in place. The seal lip 6 flares radially outward so that the outer circumference of the seal lip and therefore also the diameter is larger than the outer circumference and the diameter of the seal lip in the region of the attachment point 7 of the seal lip to the end wall 2 than at the lower free end 8. In the illustrated embodiment according to FIG. 1, this radially outward widening of the seal lip 6 is achieved by a crease 9, so that in the sectional view the wall of the seal lip resembles a toggle lever. In the illustrated embodiment according to FIG. 2 the seal lip 6 is outwardly curved, so that the outer face of the seal lip is convex and the inner face is concave.

A coaxial abutment ring 10 is molded onto the inner wall of the neck 4 and projects inward to form an abutment surface 11 for the free lower end 8 of the seal lip 6. Furthermore, the distance A from the stop surface 11 to the upper end of the neck 4 is shorter than the length, i.e. the height, L of the seal lip 6, so that when the cap 1 is attached, in particular screwed, to the neck 4 the end 8 of the seal lip 6 bears against the ring 10 and is thus compressed in such a way that the seal lip 6 is pressed outward, i.e. its diameter and circumference are increased at least in the center region. This compression of the seal lip 6 causes the curvature 12 and/or crease to project outward such that the seal lip is pressed against the inner wall of the neck 4 in a sealing manner. At the same time, the inner face of the neck and/or the outer face of the seal lip may be formed with a raised annular region, in particular an annular bead, as a defined support and a secure seal.

In alternatives that are not illustrated, the seal lip may have more than one, in particular two or three, creases. It may also be advantageous for the upper joining point, i.e. the attachment point 7, to have a material weakening, in particular a reduction in thickness, of the seal lip to thus provide hinge action.

The abutment ring 10 and thus the stop surface 11 need not have a continuous circumferential design, and the abutment ring 10 instead may be composed of individual parts with gaps therebetween.

Claims

1. A cap closure (1) to be screwed and/or pressed onto the pour neck (4) of a container, in particular a bottle, comprising an in particular annular coaxial seal lip (6) that is attached to the end wall of the cap and extends into the neck when the cap is mounted, characterized in that the seal lip (6) is outwardly curved and/or creased between the upper end (7) and the lower end (8) thereof in such a way that the curvature (12) and/or the crease (9) extends farther out and the outer face of the seal lip (6) rests in a sealing manner against the inner wall of the neck (4) when the seal lip is compressed axially.

2. The cap closure according to claim 1, a characterized in that the annular crease (9) or annular outer region of the curvature (12) forms the seal with the inner wall of the neck (4).

3. The cap closure and pour neck according to claim 1, characterized in that the pour neck (4) on its inner wall has at least one support surface (11) against which the lower end (8) of the seal lip (6) abuts.

4. The cap closure and a pour neck according to claim 3, characterized in that the support surface (11) is annular.

5. The cap closure according to claim 3, characterized in that the support surface (11) is formed by at least two projections on the inner wall of the pour neck (4).

6. The cap closure according to claim 1, characterized in that the seal lip (6) has at least two creases.

7. The cap closure according to claim 1, characterized in that the upper attachment point (7) has a material weakness, in particular a reduction in thickness, of the seal lip between the seal lip (6) and the cap end wall (2).

8. The cap closure according to claim 1, characterized in that the inner surface of the neck (4) and/or the outer face of the seal lip (6) have/has a raised location, in particular an annular bead, as a support.

9. The cap closure according to claim 1, characterized in that the axial dimension (2) of the seal lip (6) is 30-100% of the height (H) of the cap (4).

10. The cap closure according to claim 3, characterized in that a distance (A) from the support surface (11) to the upper end of the neck (4) is less than the axial length (L) of the seal lip (6).

11. In combination with a container pour neck centered on an axis, a cap fittable axially over the neck and having an end wall and a side wall; an annular seal lip extending axially inward from an attachment point at the end wall, fittable inside the pour neck, having an inner end, and of a diameter that is greater at a central region between the attachment point and the inner end than at the inner end; and a formation engageable with the inner end of the seal lip when the cap is fitted over the pour neck to axially compress the seal lip and force the central region radially outward into sealing engagement with an inner surface of the pour neck.

12. The combination defined in claim 11, further a comprising screw formations between an outer surface of the pour neck and an inner surface of the side wall.

13. The combination defined in claim 11 wherein the central region is in unstressed condition of a diameter slightly smaller than an inside diameter of the pour neck.

14. The combination defined in claim 11 wherein the lip is creased and is formed by an outer frustoconical portion and an inner frustoconical portion.

15. The combination defined in claim 14 wherein the creased lip is pressed substantially in line contact at its crease against the pour-neck inner surface when compressed axially.

16. The combination defined in claim 11 wherein the lip is of radially inwardly concave C-section.

17. The combination defined in claim 11 wherein the formation is an annular shoulder formed in the pour cap and axially engageable with the end of the lip.

18. The combination defined in claim 17 wherein an axial distance between the shoulder and an outer edge of the pour neck is slightly shorter than an axial length of the lip between the end wall and its outer end.