Closures for liquid product containers
AssigneeMetal Box Limited
InventorArnold M. Throp
Life of this patent
Estimating the term…
Abstract
A bung for closing a wine bottle in the manner of a cork is formed in a conventional injection-moulding machine from ethylene-vinyl acetate copolymer (EVA) with the addition of sodium metabisulphite and sodium bicarbonate. The sodium metabisulphite, which is in stoichiometric excess in relation to the sodium bicarbonate, decomposes to liberate sulphur dioxide. The sodium bicarbonate decomposes to liberate water and carbon dioxide. The bung as moulded accordingly has a foamed core with a liquid-impervious skin. It contains sulphur dioxide, and water enabling the sulphur dioxide to act as an oxygen scavenger when the bung is in use in a wine bottle. The bung therefore provides the bottle with a long shelf life, with no noticeable tainting of the wine.
Claims22
In a closure for a container of a wine or a wine-based product, at least a part of said closure intended to contact the product being in the form of a moulded stopper of a thermoplastics material having a foamed core within a liquid-impervious skin, the improvement comprising the feature that the foamed core has been produced by blowing the thermoplastics material with a blowing agent including a thermally decomposable metabisulphite and a water-producing compound, whereby said foamed core contains sulphur dioxide and water enabling the sulphur dioxide to act as an oxygen scavenger.
In a bung for a wine bottle, which is a moulded structure of thermoplastic material having a foamed core within a liquid-impervious skin, the improvement comprising the feature that the foamed core has been produced by blowing the thermoplastics material with a blowing agent including a thermally decomposable metabisulphite and a water-producing compound, whereby said foamed core contains sulphur dioxide and water enabling the sulphur dioxide to act as an oxygen scavenger.
In a feedstock for a moulding machine which comprises, in particulate form, a thermoplastic material and a blowing agent such that the feedstock is mouldable to produce a stopper having a foamed core within a liquid-impervious skin, the improvement which resides in that the blowing agent includes a metabisulphite capable of thermal decomposition during moulding to produce sulphur dioxide, and a compound capable during moulding of liberating water, whereby the foamed core produced on moulding the stopper contains sulphur dioxide and water enabling said sulphur dioxide to act as an oxygen scavenger.
In a method of forming a stopper for providing at least part of a container closure for wine or a wine-based product, which method comprises the steps of injecting through a nozzle and into a mould cavity a molten extrudate which comprises a thermoplastic material and a blowing agent which is at least partially thermally decomposed prior to passage through the nozzle so as to produce at least one gas operative on the reduction of pressure occuring when the extrudate enters the mould cavity to produce a foamed core for the stopper, and causing the extrudate to cool and solidify within the mould cavity to produce a liquid-impervious skin surrounding said foamed core, the improvement which resides in including in the blowing agent a metabisulphite which produces sulphur dioxide by thermal decomposition in said molten extrudate and a compound which liberates water in said molten extrudate, whereby the foamed core produced on moulding the stopper contains sulphur dioxide and water enabling said sulphur dioxide to act as an oxygen scavenger.
The method of making a stopper for providing at least part of a container closure for wine or a wine-based product, which comprises the steps of:
- (a) providing a particulate feedstock comprising thermoplastic material and thermally decomposable material which liberates a blowing agent which is at least in part sulphur dioxide and water;
- (b) heating and pressurizing said feedstock to melt the feedstock and initiate the thermal decomposition of said thermally decomposable material and extruding a limited amount of the molten feedstock into a mold cavity whereby said blowing agent expands the thermoplastic material;
- and then
- (c) recovering from the mold cavity a stopper which has a foamed core of closed pore structure within a smooth, liquid-impervious skin, the amount of molten extrudate introduced into the mold cavity in step (b) being such that the voids formed by said closed pore structure occupy between about 30-70% of the stopper volume and contain, in situ, sulphur dioxide in the presence of sufficient water to scavenge oxygen permeating into said core by reacting therewith to form sulphuric acid.
A stopper for providing at least part of a container closure for wine or a wine-based product, which comprises thermoplastic material having a foamed core of closed pore structure within a smooth, liquid-impervious skin, the voids of said foamed core containing, in situ, sulphur dioxide in the presence of sufficient water to scavenge oxygen permeating into said formed core by reacting therewith to form sulphuric acid and such voids constituting about 30-70% of the volume of said stopper.
The method of protecting wine or a wine-based product from the deleterious action of oxygen, which comprises the steps of providing a stopper of thermoplastic material having a foamed core of closed pore structure within a smooth, liquid-impervious skin, the voids of said foamed core containing, in situ, sulphur dioxide in the presence of sufficient water to scavenge oxygen permeating into said foamed core by reacting therewith to form sulphuric acid, and closing off a container having said wine or product therein by insertion of said stopper.
Dependencies are inferred from the claim text.