Stoppers of composite cork material for sparkling wines and the process for their production

Abstract

This invention concerns stoppers made from composite material for sparkling wines consisting of two types of cork agglomerate which are closely bonded and produced from two ranges of granulates of different granulometry, where the joining surface between the two agglomerates is irregular due to their interpenetration. The invention also concerns the production process of these stoppers by individual moulding (piece by piece), whereby the simultaneous feeding of the two types of granulate and the respective additives is done and the mould is closed by compression and then heated for a time for polymerisation. The granulates used are normally treated with a reactive agglomerant consisting of, for example, quasi-prepolymer based od TDI or quasi de-moulding, the unfinished stopper is stabilised, and later machined to the final dimensions.

1 . Stoppers of composite material for sparkling wines in bottles at a pressure of more than 1.5 bar which
 is resistant to the rupture by twisting when removed from the neck of the bottle rather than just by pulling, and which show good results both in relation to elasticity and homogeneity, characterised in that they comprise two types of cork agglomerate, closely bonded and produced from two-ranges of granulates of different granulometry, in the following percentages:   10 to 90% by volume of Agglomerate 1, obtained from Granulate 1 of cork with granulometry of between 15 2 and 10 mm;   90 to 10% by volume of Agglomerate 2, obtained from Granulate 2 of cork with granulometry of between 0.25 and 4 mm;   the joining surface between the two agglomerates being irregular due to their interpenetration and with Agglomerate 2 being in contact with the wine.   
   
   
       2 . Stoppers in accordance with  claim 1 , characterised in thaar they comprise 40 to 60% by volume of Agglomerate 1, and 60 to 40% by volume of Agglomerate 2. 
   
   
       3 . Stoppers made in accordance with  claim 1 ,
 characterised in that Granulate 1 has a granulometry of 3 to 7 mm and Granulate 2 has a granulometry of 0.25 to 2.5 mm.   
   
   
       4 . Stoppers made in accordance with  claim 1 , characterised in that they may also include one or more discs of natural cork at the upper and/or lower ends of the stopper. 
   
   
       5 . Process for the production of stoppers of composite material for sparkling wines in bottles at a pressure of more than 1.5 bar, characterised in that it comprises the individual moulding of the stoppers of cork agglomerate, consisting of two types of agglomerate,
 closely bonded and produced from two ranges of granulates of different granulometry, in the following percentages:   10 to 90% by volume of Agglomerate 1, obtained from Granulate 1 of cork with granulometry of between 20 2 and 10 mm;   90 to 10% by volume of Agglomerate 2, obtained from Granulate 2 of cork with granulometry of between 0.25 and 4 mm.   
   
   
       6 . Process in accordance with  claim 5 , characterised in that the agglomerate  1  is obtained in an individual mixer  1  by making a specific formulation with granulate  1 , a bonding agent and other additives and the agglomerate  2  is obtained in an individual mixer  2  by making a specific formulation with granulate  2 , a bonding agent and other additives, each of them consisting of a previously validated volume and mass called formulation,
 these raw materials being transferred to two separate systems, of variable dosage, and the mixtures thus produced are introduced into a system of pistons into a single moulding cavity, the cylindrical alveolus, fixed to the mould support plate at each of its ends.   
   
   
       7 . Process in accordance with  claim 6 , characterised in that each of the lateral feeders consists of a rotating cylindrical or semi-cylindrical cavity which receives the granulate by gravity feed with the help of a
 vibrating agitation system, the granulate having been previously wetted with additivated bonding agent.   
   
   
       8 . Process in accordance with  claim 5 , characterised in that the feeders are axially aligned with the moulding chamber and the compression piston slides inside the feeder pushing the granulate into the mould, this operation happening simultaneously in the two tops of the cylindrical moulds where the granulates are then pressed. 
   
   
       9 . Process in accordance with  claim 5 , characterised in that the translation movement of the pistons ensures the compaction, the join line of the two types of agglomerate being an irregular line where there is some interpenetration of the two parts either side of the average conceptual line of separation. 
   
   
       10 . Process in accordance with  claim 5 , characterised in that the moulds, after closure, pass to a pre-heated and temperature controlled oven, where they are kept for the necessary time for the polymerisation to occur and to ensure the mechanical stability to allow for the de-moulding, after cooling, without excessive expansion. 
   
   
       11 . Process in accordance with  claim 10 , characterised in that the moulds pass to a cooling chamber at a controlled temperature, and are cooled to a
 temperature from 30 to 80° C., preferably from 40 to 60° C., then being de-moulded by means of a piston ejector.   
   
   
       12 . Process in accordance with  claim 10 , characterised in that the moulds are cooled to 40 to 60° C. 
   
   
       13 . Process in accordance with  claim 5 , characterised in that the close bond between the two types of agglomerate is ensured by the liquid polymerisable bonding agent. 
   
   
       14 . Process in accordance with  claim 5 , characterised in that the bonding agents used can be different for each of the types of agglomerate. 
   
   
       15 . Process in accordance with  claim 5 , characterised in that the formulations used can be different for each of the types of agglomerate. 
   
   
       16 . Process in accordance with  claim 5 , characterised in that the close bond between the two types of agglomerate are guaranteed under pressure inside the mould. 
   
   
       17 . Process in accordance with  claim 16 , characterised in that the liquid polymerizable bonding agent has a macro-molecular polyurethane structure, with or without reactive functionality. 
   
   
       18 . Process in accordance with  claim 17 , characterised in that the polyurethane prepolymer used in the agglomerate of the base is precursor of the bonding agent, has a terminal molecular structure derived from 4,4′-diphenylmethane diisocyanate (MDI) and the respective polymeric analogs, or derived from toluene diisocyanate (TDI), from its isomers or analogs. 
   
   
       19 . Stoppers made in accordance with  claim 2 , characterised in that they may also include one or more discs of natural cork at the upper and/or lower ends of the stopper. 
   
   
       20 . Stoppers made in accordance with  claim 3 , characterised in that they may also include one or more discs of natural cork at the upper and/or lower ends of the stopper.