A method of manufacturing stoppers for bottles and stoppers manufactured by the method

Abstract: A method of manufacturing stoppers for bottles and stoppers manufactured by the method. The method comprises the production of a polyurethane or polyethylene thermoplastic raw material for hot moulding or extrusion, which contains the following additives: azodicarbonamide 3% - 6% sodium bicarbonate 1% - 6% tartaric acid 5% - 11% citric acid 6% - 12% carboxylic acid and salts thereof 5% - 9% humectant 1% - 4% colouring as required 1% - 2%

Description: The present invention is intended to disclose a method with original and advantageous characteristics for the manufacture of stoppers for the closure of bottles, and also refers to the stoppers produced by the application of the method. At the moment, bottles of wines, sparkling wines, and the like are corked by means of natural or agglomerated cork stoppers in accordance with production methods conventional in this industry. Natural and agglomerated cork stoppers have many disadvantages, apart from their high cost price given the increasing scarcity of the raw material of which they are made. Amongst these disadvantages may be mentioned: the emission of particles at the moment when the stopper is compressed upon it is inserted in the bottle, with possible contamination of the drink; The existence of residues of chemical products used in the surface treatment of cork stoppers, such as bleaches etc., which may lead to changes in the odour and flavour of the contents of the bottles, that is, organoleptic changes in the product; The need for a predetermined degree of humidity to achieve the pressure values and closure of the bottles; The considerable resilient-recovery time of the stopper which necessitates an appreciable waiting time in the subsequent handling of the bottles, The appearance of mould and the possibility of Coleoptera and Microlepidoptera eggs being laid during storage of the bottles; The existence of burrows excavated by ants and/or larvae, which present the danger of leakage of the bottles and the entry of oxygen; The generation of cork dust at the handling stage during the bottling process. U.S. Patent 4,188,457 refers to closures for liquid product containers injection moulded from ethylene-vinyl acetate copolymer (EVA) with the addition of sodium metabisulphite and sodium bicarbonate. U.S. Patent 5,855,287 discloses a moulded closure for a liquid container comprising a thermoplastic elastomer made out a styrene block copolymer and at least about 3% of a blowing agent. WO 00/26103 discloses a synthetic closure for bottle like containers with a thermoplastic elastomer and a metallocene catalysed ethylene-α-olephin copolymer. WO-A-9 847 783 discloses stoppers for the closure of bottles consisting of closed cell thermoplastic material and their method of manufacturing by extrusion. The present invention in accordance with claims 1 and 7 is intended to overcome the above-mentioned disadvantages, and provides stoppers in which characteristics of very quick recovery, good operation of the stopper irrespective of humidity, and firm adhesion of the stopper to the bottle are achieved, preventing, in general, any type of contamination of the product contained in the bottle. Moreover, the stoppers of the present invention are fully recyclable, and present neither problems of use for other applications after their initial use, nor ecological problems in their eventual disposal. Moreover, the stoppers produced by the present method have less resistance to compression than conventional cork so that less mechanical effort will be required by the jaws for compressing the stopper before insertion. Furthermore, there will be no leaktightness defects and, given the structure of the stopper, it will be very easy to comply with the corresponding official norms. The method of the present invention is based on the use of a first raw material which consists preferably of ester-based polyurethane with a melting point of about 220°C that has received the following additives, mixed uniformly and homogeneously: azodicarbonamide 3 - 6 wt.% sodium bicarbonate 1 - 6 wt.% tartaric acid 5 - 11 wt.% citric acid 6 - 12 wt.% carboxylic acid and salts thereof 5 - 9 wt.% humectant 1 - 4 wt.% colorant 1 - 2 wt.% The colorants are intended to achieve the colour of wood or cork according to the customer's wishes. The invention provides for other raw materials such as polyethylene, octene-based linear polyethylene, ethylene-vinyl-acetate (EVA) copolymer, or a polydimethyl-siloxane-based silicone, all with the same additives mentioned. Once the raw material has been made up, its transformation is performed on the basis of injection or extrusion, the raw material previously being melted at the temperatures appropriate for the raw material used, at which time the gas-producing endothermic reaction of the additives will take place, the raw material being introduced, in the case of the injection method, into stopper-shaped moulds or, in the extrusion method, into a die to produce a continuous stopper profile which subsequently will have to be cut, to form the closed-cell structure necessary to achieve the required mechanical and aesthetic properties in the stoppers.

Claims: A method of manufacturing stoppers for bottles comprising the production of a raw material consisting of a thermoplastic material with the following additives: azodicarbonamide 3 - 6 wt.% sodium bicarbonate 1 - 6 wt.% tartaric acid 5 - 11 wt.% citric acid 6 - 12 wt.% carboxylic acid and salts thereof 5 - 9 wt.% humectant 1 - 4 wt.% colorant 1 - 2 wt.% the raw material being heated to generate gases for the production of closed cells, being subsequently melted and injected into a stopper-shaped mould or extruded through a die to produce a profile to permit production of the stoppers by cutting. A method of manufacturing stoppers for bottles according to Claim 1, wherein the thermoplastic material is constituted by a polyethylene. A method of manufacturing stoppers for bottles according to Claim 2, wherein the polyethylene is an octene-based linear polyethylene. A method of manufacturing stoppers for bottles according to Claim 1, wherein the thermoplastic material is an ethylene-vinyl-acetate copolymer. A method of manufacturing stoppers for bottles according to Claim 1, wherein the thermoplastic material is a polydimethyl-siloxane-based silicone. A method of manufacturing stoppers for bottles according to Claim 1, wherein the plastics material is an ester-based thermoplastic polyurethane with a melting point of 220°C. Stoppers for the closure of bottles, said stoppers consisting of closed celled thermoplastic material containing 1 - 4 wt.-% humectant, 1 - 2 wt.-% colorant and the remnants of 3 - 6 wt.-% azodicarbonamide, 1 - 6 wt.-% sodium bicarbonate, 5 - 11 wt.-% tartaric acid, 6 - 12 wt.-% citric acid and 5 - 9 wt.-% carboxylic acid and salts thereof.

Inventors: MARTI SARDA FRANCISCO, ORTIZ AYCART EDUARDO, MARTI SARDA, FRANCISCO, ORTIZ AYCART, EDUARDO
Applicants: MARTI SARDA FRANCISCO, ORTIZ AYCART EDUARDO, MARTI SARDA, FRANCISCO, ORTIZ AYCART, EDUARDO
Application year: 2001
Main classification: B29C44
IPC codes: B65D39