A METAL SCREW CAP FOR BEVERAGE BOTTLE

Description

TECHNICAL FIELD

The object of the present invention is a metal screw cap for a beverage bottle consisting of a dome and a cylinder having internal thread adapted to co-operate with a threaded neck of the bottle and a liner affixed to the inner surface of the screw cap.

BACKGROUND ART.

Screw caps of the presented type are used for closing bottles for beverages, in particular for carbonated beverages. After filling and closing bottles, carbonated beverages may also be subjected to pasteurization process. Because of high temperatures and a carbon dioxide contained in beverages, it may lead to very high inner pressure inside the bottle, e.g. 5-6 bar, what can undesirably cause escape of carbon dioxide in the area of the screw cap, since the sealing in the area of the bottle closure may become unsatisfactory because of high inner pressure. However reducing of the amount of the carbon dioxide results in undesirable decrease in the beverage quality. Therefore it is necessary to seal the screw cap in such a way that the “escape” of carbon dioxide does not happen. A permeable closure may also cause penetration of air from outside inside the bottle, what may lead to fermentation of the beverage, and in case of beverages comprising oxidisable substances, to alteration of the chemical composition of the beverage (what is particularly undesirable in case of the beverages comprising vitamins or medicinal substances).

Patent specification PL374268A discloses a screw cap for containers equipped with a threaded neck, in particular polyethylene bottles, in which beverages containing carbon dioxide are stored. The cap comprises a top plate, a cap jacket provided with an interior thread, an inner sealing ring having cylindrical shape, whose part extends outside in circumferential way and an outer sealing ring also having cylindrical shape, which is placed concentrically in relation to the inner ring.

Patent specification US2016288945 discloses a bottle with a screw cap made from light metal intended in particular for storing carbonated beverages. Improvement in relation to the tightness of the closure of the bottle was achieved by modification of the upper edge of the neck of the bottle and appropriate adjustment of the screw cap to such modified neck.

Patent specification US2016318674 discloses a screw cap intended for closing bottles for storing oxygen-sensitive medicines, which comprises a dome and a threaded skirt. Outstanding seating was achieved by adding annular pliable gasket secured to the circumferential portion of the inner section of the dome and a layer of lacquer applied on the inner surface of the dome inside the gasket. In this construction, threaded connection of the twisted closing skirt with the pharmaceutical bottle under pressure causes, that the pliable gasket seals the upper edge of the pharmaceutical bottle, to provide a gas-tight seal.

DISCLOSURE OF THE INVENTION

A metal screw cap for a beverage bottle consisting of a dome and a cylinder having internal thread adapted to co-operate with a threaded neck of the bottle and a liner affixed to the inner surface of the screw cap in accordance with the invention is characterised by this that the dome is concave and is connected with the cylinder through a top ring, where between the dome and the top ring there is a circumferential groove having the radius of the inner curvature R1.

The cylinder is connected with a security band by frangible bridges.

The depth of the screw cap is from 1 to 10 mm, preferably from 1.2 to 8 mm.

The radius R1 is from 0.5 to 4 mm, when the screw cap is not twisted.

The radius R1 is from 1 to 3 mm.

The diameter of the cylinder is from 10 to 100 mm.

The radius of the curvature of the dome of the screw cap is from 35 to 105 mm.

The radius R2 is from 45 to 50 mm.

The screw cap according to the invention allows to increase force of the sealing of the system by use of the inner pressure. Special shape of the screw cap causes that the pressure inside the bottle deforms the screw cap in a controlled way and pushes its wall to the wall of the bottle in the place, where the groove is in the dome. Thereby the screw cap according to the invention, is a self-sealing screw cap.

The subject of the invention is disclosed at the drawings, where FIG. 1 illustrates the screw cap, FIG. 2—its cross-section, FIG. 3—a cross-section of the neck of the bottle with the screw cap, FIGS. 4 and 5—illustrate the mode of action of the screw cap, FIG. 4—before closing, FIG. 5—after closing.

EXAMPLE

The dome 1 is concave and is connected with the cylinder 3 having the height H through the top ring 2. Between the dome 1 and the top ring 2 is placed the circumferential groove having the radius of the inner curvature R1. The cylinder 3 is equipped with a tread 4. The cylinder 3 is connected with a security band 5 by the frangible bridges 6. The depth of the screw cap D is from 1 to 10 mm, preferably from 1.2 to 8 mm. The radius R1 is from 0.5 to 4 mm, when the screw cap is not twisted. Preferably the radius R1 is from 1 to 3 mm. The diameter of the cylinder S is from 10 to 100 mm. The radius R2 of the curvature of the dome 1 of the screw cap is from 35 to 105 mm. Preferably the radius R2 is from 45 to 50 mm.

Inside of the screw cap is lined with a liner 7.

The screw cap 8 is applied on the threaded neck 9 of the bottle 10. Twisting of the screw cap causes sealing of the outlet of the bottle, because the radius R1 is reduced, owing to that the wall of the screw cap is being pushed to the wall of the bottle.