Screw cap for pressurised containers

Abstract

The invention relates to a screw cap for containers with a threaded neck, in particular PET bottles designed to hold beverages containing CO2. Said cap comprises a top plate (1), an approximately cylindrical cap jacket (2), provided with an interior thread (3), an approximately cylindrical inner sealing collar (4), emanating from the top plate (1) and having an annular continuous region that projects radially outwards and an essentially cylindrical outer sealing collar (5), which concentrically surrounds the inner sealing collar (4). The maximum outer radius of the inner sealing collar and the minimum inner radius of the outer sealing collar differ only slightly, preferably by less than 2 mm and in particular by less than 1 mm and the inner and outer sealing collars (4, 5) are designed to receive the upper region of a bottle neck (11) in the annular gap formed between said collars. The aim of the invention is to provide a screw cap, which in general retains the excellent sealing properties of the known screw cap, even in extreme environmental conditions and is at the same time capable of limiting the pressures that occur in a container with a screw cap, without losing its sealing function. To achieve this, the cap is provided with devices (6, 7), which limit the axial depth of penetration of the edge of a bottle neck (11) into the gap between the inner (4) and the outer sealing collar (5).

Description

BACKGROUND OF THE INVENTION [0001] The present invention relates to a screw cap for containers with a threaded neck, in particular PET (polyethylene terephthlate) bottles, which are designed to hold drinks containing CO2, with a head plate, a roughly cylindrical cap shell with internal thread, an essentially cylindrical inner sealing web extending from the head plate with a continuous annular region projecting radially outwards and an outer, essentially cylindrical sealing web concentrically surrounding the inner sealing web, the maximum external radius of the inner sealing web and the minimum internal radius of the outer sealing web differing only slightly and preferably by less than 2 mm and in particular by less than 1 mm, and being designed to accommodate and seal the upper region of a bottle neck in the thus-formed intermediate space. [0002] Such a screw cap is already known from European patent application No. 98 909 299, filed by the same applicant as the present application ...

AI Technical Summary

Benefits of technology

"The invention is a screw cap for PET bottles that prevents the bottle neck rim from penetrating the space between the inner and outer sealing webs. This is achieved by adding structures to the screw cap that limit the depth to which the bottle neck rim can penetrate this space. This design ensures that the cap can still seal the bottle effectively, even when the rim is in place."

Problems solved by technology

For example, extremely high pressures can build up in such a PET bottle under extremely high outdoor temperatures, particularly if suitably filled bottles are exposed to direct sunlight, combined with a particularly high proportion of carbon dioxide in the liquid or beverage.

This causes a very considerable strain, both on the bottle and on the closure, and can also lead to a clearly visible bulging in the main body of the bottle.

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