Screw closure and method for producing a screw closure

Abstract

The invention relates to a screw closure (1) for containers for accommodating pressurized liquids, in particular for beverage bottles containing carbonated beverages, which screw closure is designed as a screw cap having a sealing face (2) that can be screwed against the mouth opening of the container, wherein a concentrically arranged projection (4) projecting from the cap base (3) is provided at least on the cap base (3) located inside the sealing face in the radial direction, the outer diameter of which projection corresponds to the inner diameter of the mouth opening. The projection (4) has a first sealing lip (5) and a second sealing lip (6), and holes (7) are provided between the sealing lips (5, 6). The invention also relates to a method for producing a screw closure (1) of this kind.

Description

SCREW CAP AND METHOD FOR PRODUCING A SCREW CAP Technical area

[0001] The invention relates to a screw closure for containers for holding pressurized liquids, in particular for beverage bottles containing carbonated beverages. The screw closure is designed as a screw cap with a sealing surface that can be screwed against the mouth of the container. At least on the cap base located radially within the sealing surface, a concentrically arranged projection is provided, projecting from the cap base, whose outer diameter corresponds to the inner diameter of the mouth. The invention further relates to a method for producing such a closure. State of the art

[0002] Such a screw cap is shown in AT524044A. The screw cap shown serves to create a controlled pressure equalization between the container interior and the environment upon opening. It is intended to ensure that, particularly when opening carbonated beverages, the resulting foam does not escape from the bottle but is contained by the cap. However, the cap shown in Fig. 1 of AT 524044 A4 has a large protrusion, which takes up considerable volume and consumes a considerable amount of material. Furthermore, foaming the protrusion material requires additional technical effort, which increases the cost of the cap.

[0003] Another screw cap is shown in US5056681A. Here, the screw cap is used to hold a prize in a competition. The screw cap also has a part that allows gas from the container to escape through gaps when the bottle is opened. However, this screw cap is expensive to manufacture and does not ensure that liquid will not leak out when frothing a beverage in the bottle. Description of the invention

[0004] The aim of the invention is to eliminate the above-mentioned disadvantages of the prior art and to provide a screw cap which prevents the leakage of liquid during the opening of a container with foaming contents and which is inexpensive to manufacture.

[0005] According to the invention, this is achieved in that the projection has a first and a second sealing lip and there are holes between the sealing lips. By using two sealing lips, only a small amount of material needs to be used to create two additional sealing surfaces together with a container. When the screw cap is unscrewed from the container, a gap first forms between the top of the container's mouth opening and the sealing surface of the screw cap. As the screw cap is screwed on further, the first sealing lip detaches from the container wall of the mouth opening. Gas can now be exchanged between the container and the environment via the holes. Liquids have difficulty flowing through the holes and any foam that may form is held back by the holes and the second sealing lip.

[0006] It is advantageous if the screw cap has at least one additional projection whose inner diameter corresponds to the outer diameter of the mouth opening. This additional projection presses the first and second sealing lips even more securely and firmly against the container wall of the mouth opening.

[0007] It is advantageous if the holes have a diameter in the range of 0.005 mm to 0.1 mm, preferably in the range of 0.01 mm to 0.05 mm. The small diameter of the holes ensures that no liquid can flow through them.

[0008] Another advantageous feature is that the holes form inclined passages between the interior of the container and the space between the first and second sealing lips, or that the passages run essentially parallel to the extension direction of the projection through the second sealing lip. An inclined arrangement can be advantageous when creating the holes during production. Creating micro-bores directly in the second sealing lip parallel to the projection itself can also have manufacturing advantages.

[0009] According to the invention, a method for producing the screw cap can be used in which the screw cap is manufactured by injection molding and the holes are subsequently created by laser micro-drilling. This enables fast and cost-effective production. Short description of the drawings

[0010] The invention will now be explained in more detail using an embodiment with the aid of the accompanying drawing. Fig. 1 shows a screw cap according to the invention in a schematic sectional view. Way(s) of carrying out the invention

[0011] The screw cap 1 can be used to screw containers, bottles or the like. When the screw cap 1 is attached to a bottle, the sealing surface 2, which rests on the top side of the bottle's mouth, and the first and second sealing lips 5 and 6, which rest on the inside of the mouth, serve to hermetically seal the bottle. The projection 8 ensures that the pressing force of the first and second sealing lips 5 and 6 is increased when screwed on, and thus the contact of the sealing lips 5, 6 with the bottle is improved. When the screw cap 1 is screwed off the bottle, the upper edge of the bottle first detaches from the sealing surface 2. At this point, the bottle is still hermetically sealed by the first sealing lip 5.If the screw cap 1 is turned further in the opening direction, the first sealing lip 5 loses contact with the inside of the bottle and now, in the presence of negative or positive pressure, gas can be exchanged between the bottle and the environment. The second sealing lip 6 continues to form an airtight contact with the inside of the bottle, while the holes 7 enable gas exchange with the environment. If the screw cap 1 is turned further in the opening direction, the second sealing lip 6 finally loses contact with the inside surface of the bottle and both air and liquid can flow between the screw cap 1 and the bottle. At this point, however, pressure equalization is already complete and, as a rule, no more foam escapes.If the screw cap 1 is unscrewed further, the bottle is completely opened and any bottle contents can be emptied from the bottle or filled into the bottle.

[0012] The screw cap 1 therefore moves through five different positions. In a first position, the bottle is closed at all three sealing surfaces 1 or sealing lips 5, 6. In a second position, the first 5 and second sealing lip 6 seal the bottle. In a third position, only the second sealing lip 6 seals and gas can be exchanged between the bottle and the environment to equalize the pressure. In a fourth position, no sealing surface is closed anymore and both gas and liquid can be exchanged between the bottle and the environment (via the thread), as would be the case with a conventional cap after the first movement section. In a fifth position, the bottle is completely open and the screw cap is no longer in contact with the bottle.

[0013] This rotation of the positions has the great advantage that in the third position, only gas can be exchanged between the bottle and the environment via holes 7. This can ensure that, for example, when frothing a carbonated beverage, liquid cannot escape, thus preventing the carbonated beverage from accidentally getting onto clothing, the outer part of the bottle, or the environment.

[0014] In Fig. 1, the holes 7 are shown horizontally, but an oblique arrangement of the holes 7 is also possible. This enables easier use of the laser, in particular, if the laser can simply create the holes 7 on the projection 4 directly from outside the screw cap 1. It is advantageous if the material of the screw cap 1 is simply vaporized. The laser can be pulsed in such a way that it only penetrates the material thickness of the projection 4 and not the outer walls of the closure. This enables fast and cost-effective production. The same applies to a vertical arrangement of the holes running parallel to the projection 4. The holes are then located directly within the bead that forms the second sealing lip 6, completely on the outside of the projection 4.

[0015] The distance between the first sealing lip 5 and the second sealing lip 6 can be adjusted to determine how many turns are needed to get from position three to position four. The choice of distance therefore determines how long the screw cap 1 needs to be screwed on until not only gas but also liquid can escape. Beverages with different foaming behavior can thus be easily provided with suitable closures. The holes can also be used to limit the pressure on the closure itself. In principle, conventional bottle closures are designed to withstand a maximum overpressure of 10 bar. This is achieved across the sealing surface 2 and the two sealing lips 5, 6.The holes allow excess pressure, which may arise due to storage or incorrect handling, to be released in a controlled manner without any liquid escaping.

Claims

Screw cap (1) for containers for holding liquids under pressure, in particular for beverage bottles containing carbonated beverages, which is designed as a screw cap with a sealing surface (2) that can be screwed against the opening of the container, wherein at least on the cap base (3) located in a radial direction within the sealing surface a concentrically arranged projection (4) extending from the cap base (3) is provided, the outer diameter of which corresponds to the inner diameter of the opening, characterized in that the projection (4) has a first (5) and a second sealing lip (6) and holes (7) are located between the sealing lips (5, 6). Screw cap (1) according to claim 1, characterized in that the screw cap (1) has at least one further projection (8) whose inner diameter corresponds to the outer diameter of the opening. Screw cap (1) according to claim 1 or 2, characterized in that the holes (7) have a diameter in the range of 0.005 mm to 0.1 mm, preferably in the range of 0.01 mm to 0.05 mm. Screw cap (1) according to one of claims 1 to 3, characterized in that the holes form oblique passage channels between the interior of the container and the space between the first (5) and the second sealing lip (6), or that the passage channels run substantially parallel to the extension direction of the projection (4) through the second sealing lip (6). Method for manufacturing a screw cap (1) according to one of claims 1 to 4, characterized in that the screw cap (1) is manufactured by injection molding and the holes (7) are subsequently produced by laser micro-drilling.

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