Plastic closing cap with sealing ring

Abstract

A closing cap molded in one piece from a plastics material for sealing a container with a threaded neck has a top plate (3), an annular skirt (4) with an internal screw thread (5) adapted to cooperate with the threaded container neck (2), and an integrally molded deformable annular sealing ring (6) extending downwardly from an inner surface of said top plate (3) and spaced radially inwardly of the annular skirt (4), wherein when the closing cap (1) is screwed onto the container neck (2), the sealing ring (6) is deformed outwardly and is fully conformed to the outer surface of the container neck (2) without being clamped between the container neck (2) and the annular skirt (4) and without being pressed against the annular skirt (4).

Description

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a plastic closing cap for a container with an annular sealing ring.

BACKGROUND OF THE INVENTION

Container closures moulded in one piece from a plastic material including downwardly depending seals are well known in the art. The purpose of these arrangements is to enable a cap to be easily screwed onto a container neck such that the edge of the container neck seals against the underside of the top plate of the cap, while the sealing ring is pressed into firm sealing engagement with the edge of the container neck.

In the case of containers made of plastics material it can certainly happen that the edge of the container neck has suffered minor damage, deformation and/or irregularities caused during the manufacturing procedure, and which are sufficient to have a negative effect on the sealing engagement between the edge of the container neck and sealing elements of the cap.

Thus, a deteriorated seal in the case of bottles for carbonated drinks can have the result that gas escapes from the bottle and after a few days of storage the drink has lost its carbon dioxide and is tasteless.

The known closures therefore still do not guarantee absolutely sealing integrity in the event of minor damage or deformation of the edge of the container neck.

In addition, caps when applied to plastic containers for sterilized beverage e.g. milk or diary products, must also meet rigid requirements to prevent contamination and the overall cap structure must be leak-proof. In order to provide a liquid-tight seal it is, therefore, known to use either a sealing laminated membrane on the opening of the container or a separate liner inside of the cap.

However, these arrangements are characterized by higher manufacturing and/or recycling costs while cannot guarantee reliable sealing integrity.

SUMMARY OF THE INVENTION

It is, therefore, an object of the present invention to provide an improved plastic closing cap, which overcomes the deficiencies of the prior art and ensures reliably the sealing function and prevents leaks in the event of minor damage or deformation of the container neck.

A further aspect of the present invention is to provide a closing cap particular useful for sterilized products such as milk or diary products which provides easy opening and reclosing of the container and effectively sealing prior to and after reclosing.

In accordance with the above objects of the present invention, a closing cap moulded in one piece from a plastics material for sealing a container with a threaded neck is provided comprising a top plate which is substantially in the form of a circular disc a substantially cylindrical peripheral portion extending downwardly from said top plate, said peripheral portion having an internal screw thread adapted to cooperate with the threaded container neck, an integrally moulded deformable sealing ring extending downwardly from an inner surface of said top plate and spaced radially inward of the substantially cylindrical peripheral portion, wherein when said closing cap is applied onto the threaded container neck, said sealing ring is adapted to radially deform outwardly and seal at least substantially along the outer surface of the container neck by virtue of the elastic return forces without being clamped between the container neck and the substantially cylindrical peripheral portion and without being pressed against the substantially cylindrical peripheral portion.

Further preferred embodiments of the present invention are defined in dependent claims 2 to 17.

The closing cap of the invention is ergonomic by offering compactness, and it adapts very easily to any container necks.

In the closed position it ensures perfect sealing. The cap is also able to retain a liquid-tight seal after a period of time due to its configuration in conjunction with its material's characteristics.

Operations of assembling the cap together on the neck of the container is quick and very easy.

Other objects and advantages of the present invention will become apparent to those skilled in the art in view of the following detailed description taken in conduction with the accompanying drawings, wherein like reference numbers refer to similar parts throughout the drawings, and wherein:

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B show a perspective view, partially broken away, of a closing cap according to the present invention applied to the container prior to, and after formation of a seal;

FIGS. 2A and 2B show a perspective view, partially broken away, of a second alternative closing cap according to the present invention applied to the container prior to, and after formation of a seal;

FIGS. 3A and 3B show a perspective view, partially broken away, of a third alternative closing cap according to the present invention applied to the container prior to, and after formation of a seal;

FIGS. 4A and 4B show a perspective view, partially broken away, of another alternative closing cap according to the present invention applied to the container prior to, and after formation of a seal;

FIGS. 5A and 5B show a partial cross-sectional view of an alternative closing cap according to the present invention in place on a container prior to, and after removal of the laminated disc; and

FIGS. 6A and 6B show a partial cross-sectional view of a further alternative closing cap according to the present invention in place on a container prior to, and after removal of the laminated disc.

DETAILED DESCRIPTION OF THE INVENTION

Referring first to FIG. 5A of the drawings, the closing cap 1 is moulded in one piece from a resilient plastics material and has a top plate 3 in the shape of a circular disc and an annular skirt 4 peripherally downwardly depending therefrom. The annular skirt 4 has an internal screw thread 5. On the inner surface of the top plate 3 extending downwardly there is an integrally moulded thin, deformable annular sealing ring 6 of uniform thickness which is of substantially cylindrical construction. In addition, the sealing ring 6 is disposed at a position spaced radially inwardly of the annular skirt 4, and concentric with said annular skirt. Said sealing ring 6 has a length such as to permit its portion adjoining its free edge to extend along the upper outer surface of the container neck 2. The sealing ring 6 is made of the same plastic material as the cap 1 and preferably has a thickness of equal or less than 0.8 mm.

A container has an annular neck 2 with an external thread formed thereon.

In accordance with one aspect of the present invention the closing cap is adapted for use with a container, which is a thin-walled light weight blow-molded plastic bottle (e.g. for milk or diary products) provided with an externally screw-threaded neck 2. The container neck 2 has above its threads an upwardly and inwardly directed portion 8 which is tapered (e.g. frusto-conically) and may have a substantially radially inwardly directed rim 9 for engagement with a stop means 7 of the closing cap referred to below.

In use, as depicted in FIGS. 1A and 1B, the closing cap 1 is applied to the container neck 2 so that the top of the container neck moves upwardly as in FIG. 1A to adopt the position shown in FIG. 1B.

As it does so the sealing ring 6 first comes into contact with the outer surface of the container neck 2 while the closing cap 1 is being rotated during the capping operation. Further rotation of the closing cap l relative to the container neck 2 causes the container neck 2 to move upwardly relative to the closing cap 2 to adopt the position shown in FIG. 1B.

On the inner surface of the top plate, the sealing ring 6 is disposed at a radius approximately equal to the radial distance of the middle of the tapered portion 8 of the container neck 2. Therefore, during the capping operation the sealing ring 6 is being urged away by the tapered portion 8 of the container neck 2 and thus it is deformed radially outwardly, and lies against the outer surface of the tapered portion 8 of the container neck, and has a sufficient length in contact with it.

Hence, the sealing ring 6 is fully conformed to the outer surface of the container neck 2 by virtue of its elasticity without being clamped between the container neck 2 and the annular skirt 4 and without being pressed against the skirt 4.

In this condition an effective tight seal is formed between the outer surface of the tapered portion 8 of the container neck 2 and the inner surface of the sealing ring 6.

Moreover, due to the elastic return forces which occur in that case and the deformation of the sealing ring 6 in conjunction with the resilience of the plastics material, said seal is maintained despite relaxation.

At the same time, because of this radial displacement of the sealing ring 6, there is a pivotal force applied to the inner surface of the top plate 3 which tends to resist doming in conjunction with the stop means 7 of the cap referred to below.

Referring now to FIGS. 2A and 2B of the drawings, another modification of the present invention is shown in which the sealing ring is L-shaped and sealing integrity is afforted by virtue of engagement of the short side of the L-shaped sealing ring, which is parallel to the top plate of the cap, with the upper portion (tapered portion) of the container neck, wherein said short side is displaced inwardly and is then clamped between the outside surface of the container neck and the long side of the L-shaped sealing ring.

FIGS. 3A and 3B show another modification of the invention in which the sealing ring is attached to the annular skirt above its internal threads and is substantially parallel to the top plate of the cap.

FIGS. 4A and 4B show a further modification of the present invention in which the sealing ring is attached to the inner surface of the top plate of the cap at a position spaced radially inwardly of the annular skirt and extends downwardly and inwardly (conical) from the top plate of the cap.

Arrangements of the foregoing type are used with a further main feature of the invention shown in FIGS. 1 to 6, i.e. the stop means 7.

FIGS. 5A and 5B show an alternative modification for use in cases where there is a laminated disc 10 sealed on the container opening.

The laminated disc is attached to and sealed on the containers by means of a plastic heat shrinkable tube which insures a tight sealing engagement about the container opening. This arrangement offers many advantages, e.g. high shapping nature and high-temp resistance, tight sealing and better fineness.

The stop means 7 is a shallow ring which extends downwardly from the inner surface of the top plate 3. It is disposed radially inwardly of the sealing ring 6, and has an external diameter which is slightly smaller than the inner diameter of the inwardly directed rim 9 of the container neck 2, namely slightly smaller than the container opening. The stop means is further provided with a tapering conical tip.

As shown in FIG. 5A, during the capping procedure, the laminated disc 10 at the region of the rim portion 9 of the container neck 2 comes into contact with the tapering tip of the stop means 7 which has the effect of limiting the upwardly movement of the container neck 2. In this condition the closing cap 1 is screwed onto the container neck 2, the sealing ring 6 is not deformed and a liquid-tight seal is provided by the laminated disc 10.

Once the container has been opened and the laminated disc 10 has been removed, the reclosing of the container is achieved in that the closing cap 1 is further rotated, and due to the relative movement between the container neck 2 and the cap 1, the stop means 7 adopts the position shown in FIG. 5B. Only just during this reclosing procedure the sealing ring 6 comes into contact with the tapered portion 8 of the container neck 2 and is thereby deformed.

Because the stop means 7 is intended essentially and primarily as a restriction and secondly as a seal, the main sealing effect also in this modification is to be found between the outer surface of the tapered portion 8 of the container neck 2 and the inner surface of the sealing ring 6.

Further, because the stop means 7 is disposed in-board of the sealing ring 6, it tends to strengthen the central portion of the top plate 3. This resists doming.

It will thus be seen that during reclosing of the cap 1 to the container neck 2, the outer surface of the tapered portion 8 of the container neck 2 first comes into contact with the sealing ring 6 thereby causing effective sealing.

It will also be appreciated that by virtue of the relative thickness of the flexible sealing ring 6 taken with the effects of the stop means 7, a more effective seal is provided than previously.

The stop means 7 and the stiffness of the top plate 3 together result in that the effects of doming upon the sealing ring 6 are reduced thus ensuring that the sealing ring 6 does not get pulled out of sealing engagement with the container neck 2.

Further, the stop means 7 acts as a stiffening rib and may be continuous or discontinuous.

The arrangement shown in FIGS. 6A and 6B is similar to that in FIGS. 5A and 5B, but in FIGS. 6A and 6B the stop means 7 is an annular disc depending from the inner surface of the top plate 3 of the cap and is generally trapezoidal in cross section, decreasing in a direction downwardly and away from the the top plate.

The inventive closing caps are preferably made by injection moulding of polypropylene or high density polyethylene plastics materials.

The stop means is intended to have sealing properties but needs to be used in conjunction with a primary seal for example as hereinbefore set forth.

The closing cap is designed to be fitted onto a glass or plastic container, such as a soft drink bottle. It should be noted that the container can hold various liquids including, but not limited to, diary products, a carbonated beverage, a non-carbonated liquid or a vaporized product.

Closures of this type may be produced, preferably by injection moulding, with or without tamper evident band. Preferably the skirt terminates in a plurality of frangible bridges supporting a tamper evident band for cooperation with a plain security band on the outer neck portion of the container neck in the usual way.

The skirt is preferably provided with external knurling or vertical ribbing to improve manual grip.

The thickness of the sealing ring may be preferably more than 0.80 mm.

While preferred embodiments have been shown and described obviously minor modifications in design and construction can be effected in the invention without departing from the spirit and scope thereof, as defined in the appended claims.

Claims

1. A closing cap moulded in one piece from a plastics material for sealing a container with a threaded neck comprising:

a top plate which is substantially in the form of a circular disc;

a substantially cylindrical peripheral portion extending downwardly from said top plate, said peripheral portion having an internal screw thread adapted to cooperate with the threaded container neck; and

an integrally moulded deformable annular sealing ring extending downwardly from an inner surface of said top plate and spaced radially inward of the substantially cylindrical peripheral portion, wherein when said closing cap is applied onto the threaded container neck, said sealing ring is adapted to radially deform outwardly and seal at least substantially along the outer surface of the container neck by virtue of the elastic return forces without being clamped between the container neck and the substantially cylindrical peripheral portion and without being pressed against said substantially cylindrical peripheral portion.

2. The closing cap according to claim 1, wherein said sealing ring is substantially cylindrical.

3. The closing cap according to claim 1, wherein said sealing ring is L-shaped.

4. The closing cap according to claim 1, wherein said sealing ring has a uniform thickness of equal or less than 0.80 mm.

5. The closing cap according to claim 1, wherein said outer surface of the container neck has, above its threads, an upwardly and inwardly directed tapered portion and a substantially radially inwardly directed rim and said sealing ring is disposed at a radius approximately equal to the radial distance of the middle of the tapered portion of the container neck.

6. The closing cap according to claim 5, wherein said sealing ring is deformed radially outwardly by the tapered portion of the container neck and is fully conformed to the outer surface of the container neck by virtue of its elasticity without being pressed against the substantially cylindrical peripheral portion.

7. The closing cap according to claim 5 further comprising a continuous or discontinuous stop means extending downwardly from the inner surface of said top plate and disposed radially inwardly of said deformable sealing ring.

8. The closing cap according to claim 7, wherein said stop means has an external diameter which is slightly smaller than an inner an inner diameter of the substantially radially inwardly directed rim of the container neck.

9. The closing cap according to claim 7, wherein said stop means is adapted to limit the upwardly movement of the container neck.

10. The closing cap according to claim 7, wherein said stop means is adapted to be inserted in the opening of the container neck after removal of a-sealing laminated disc.

11. The closing cap according to claim 10, wherein said sealing ring only just during the reclosing procedure and after removal of the laminated disc first comes into contact with the tapered portion of the container neck and is thereby deformed.

12. The closing cap according to claim 7, wherein said stop means is a shallow ring with a tapering conical tip.

13. The closing cap according to claim 7, wherein said stop means is an annular disc.

14. The closing cap according to claim 1, wherein said substantially cylindrical peripheral portion has at its distal end a tamper evident band for cooperation with a security band on the outer neck portion of the container neck.

15. The closing cap according to claim 1, wherein said substantially cylindrical peripheral portion is provided with external knurling.

16. The closing cap according to claim 1, wherein said closing cap is made by injection moulding.

17. An assembly of a container having a threaded neck and a closing cap wherein said closing cap is moulded in one piece from a plastics material for sealing a container with a threaded neck and comprises:

a top plate which is substantially in the form of a circular disc:

a substantially cylindrical peripheral portion extending downwardly from said top plate, said peripheral portion having an internal screw thread adapted to cooperate with the threaded container neck; and

an integrally moulded deformable annular sealing ring extending downwardly from an inner surface of said top plate and spaced radially inward of the substantially cylindrical peripheral portion, wherein when said closing cap is applied onto the threaded container neck, said sealing ring is adapted to radially deform outwardly and seal at least substantially along the outer surface of the container neck by virtue of the elastic return forces without being clamped between the container neck and the substantially cylindrical peripheral portion and without being pressed against said substantially cylindrical peripheral portion.