Technological background In this field, containers comprising a receptacle for holding a beverage, surrounded by a reaction chamber which is divided into two compartments containing water and ammonium nitrate, respectively, are known. Means are also provided in the container for triggering the reaction between the two substances which, as is known, bring about cooling of the surrounding atmosphere and, in particular, also of the beverage held in the receptacle, when they are placed in contact with one another, giving rise to an endothermic reaction.

A self-cooling container of the above-mentioned type is described in Swedish patent No. 9802677.

However, these containers have some disadvantages connected with the specific physical and chemical characteristics of unreacted ammonium nitrate, amongst which is its explosive capacity.

The explosive capacity of unreacted ammonium nitrate may compromise the overall safety of known containers, particularly in the management of the production (storage and handling of the nitrate) and the disposal of the containers.

Description of the invention The problem underlying the present invention is that of providing a self- cooling container which is designed structurally and functionally to overcome the disadvantages explained above with reference to the prior art mentioned.

Within the scope of this problem, a primary object of the invention is to provide a container suitable for the preservation and consumption of beverages which can be managed safely at every stage of its life and, finally, which can be produced at low cost.

This problem is solved by the present invention by means of a self-cooling container formed in accordance with the appended claims.

Description of the drawing The characteristics and the advantages of the invention will become clearer from the detailed description of a preferred embodiment thereof, described by way

of non-limiting example, with reference to the appended drawing in which the sole figure is a view of a self-cooling container formed in accordance with the present invention, in partial axial section.

Preferred embodiments of the invention In the drawing, a self-cooling container formed in accordance with the present invention is generally indicated 1.

The container 1 comprises a generally beaker-shaped shell 2 in which a receptacle 3, arranged for holding a beverage is fitted.

An inwardly-bendable, convex base 4 identified in the shell 2 is surrounded by a lateral skirt 5 which projects relative to the base 4 with a collar 7 for supporting the container 1 in a stable manner, in spite of the convex shape of the base 4.

The receptacle 3 is arranged coaxially inside the shell 2 in a manner such that their respective mouths are substantially coplanar.

An annular lip 9 extends radially from the rim of the mouth 8 of the receptacle 3 and a removable film 10 (referred to in the field by the term "peelable") is fitted thereon, to close the receptacle 3. The annular lip 9 is also connected, in a leaktight manner, for example, by heat-sealing, to a corresponding lip 11 of the mouth of the shell 2.

A chamber 12, sealed from the exterior in a leaktight manner, is thus identified in the container 1, and is defined as a whole by the receptacle 3 and by the base 4 and the skirt 5 of the shell 2.

Means for cooling the container 1 are provided in the chamber 12 and comprise a first component and a second component which can react endothermically when placed in contact.

The first and second components are disposed in the chamber 12 in respective compartments 13,14 thereof, that are separated by an easily-broken membrane 15, in a manner such that the first compartment 13 is in contact with the base 4 and the second compartment 14 is in contact with the receptacle 3.

The membrane 15 extends across the chamber 12 in an intermediate position between the base 4 of the shell 2 and the receptacle 3 and is fixed by its peripheral rim to a shoulder 16 formed in the skirt 5.

Means for triggering the reaction between the first and second components are also provided in the container 1 and comprise a breaker element 17 of tubular cross-section, which extends axially through the first compartment 13 towards the membrane 15. A first end of the breaker element 17 is fixed firmly to the base 4 and its opposite, free end is suitably shaped to facilitate tearing of the membrane 15, when operated.

An insulating sleeve 18 is arranged coaxially around the shell 2, spaced from the skirt 5, in order to insulate the chamber 12 thermally from the atmosphere outside the container 1, minimizing dissipation therefrom. The opposite ends of the insulating sleeve 18 are connected to the lip 11 and to the shoulder 16 of the shell 2, respectively.

According to the invention, the first component of the cooling means, which is disposed in the first compartment 13 of the chamber 12, comprises water and the second component which is provided in the second compartment 14, comprises hydrated sodium thiosulphate, preferably in pentahydrate form (Na2S203.5H20).

Sodium thiosulphate pentahydrate is soluble in water and the corresponding solvation reaction is endothermic.

Tests carried out by the Applicant have shown an adequate efficiency in terms of cooling of the beverage contained in the receptacle 3 when sodium thiosulphate pentahydrate and water are present in a ratio of between 0.75 and 2 by weight, according to the desired rate of cooling and taking account of the temperature-dependence of the solubility of sodium thiosulphate in water.

The best efficiency was found with a ratio of 1.625 by weight between sodium thiosulphate pentahydrate and water.

The rate of the solvation reaction of sodium thiosulphate is also determined by its particle size. Further tests carried out by the Applicant have enabled an average particle size of less than 1.2 mm, and preferably of between 0.5 and 0.7 mm, to be defined as optimal. However, average particle sizes of up to 2 mm are also acceptable. Within the preferred range of particle sizes, the apparent density of the sodium thiosulphate at ambient temperature is about 0.9 g/cm3.

The quantities of components provided in the respective compartments 13 and 14 are correlated with the desired degree of cooling, with the dimensions of

the container, with its mass, and with the degree of insulation of the chamber 12 from the atmosphere outside the container 1, as well as with the quantity of beverage to be cooled.

To improve the efficiency of the above-mentioned reaction with regard to the cooling of the beverage contained in the receptacle 3, the receptacle is made of a material having good thermal conductivity, for example aluminium, whereas the shell 2 and the sleeve element 18 are made of material with poor thermal conductivity, for example, of polypropylene or other plastics material.

In order to bring about cooling of the beverage contained in the receptacle 3, it suffices to press on the base 4 of the shell 2, deforming it in a manner such that the breaker element 17 is moved towards the membrane 15 and tears it. As a result of the particular shape of the base 4, when it is released, it bends outwardly towards the starting position, withdrawing the breaker element 17 from the tear produced in the membrane 15. This promotes a rapid flow of water from the first compartment 13 to the second compartment 14, giving rise to the above- described solvation reaction as the water and the sodium thiosulphate come into mutual and intimate contact.

The speed and efficiency of the reaction is optimized by inverting the container 1 and shaking it. This in fact promotes the flow of water into the second compartment 14 and increases the rate of solvation of the sodium thiosulphate.

It is pointed out that the geometrical shapes of the shell 2 and of the receptacle 3 are such that the chamber 12 also extends toroidally around the receptacle 3 so that the reaction mixture can utilize the largest possible thermal- exchange surface.

In a first variant of the present invention, the second component comprises a mixture composed of thiosulphate salt, of urea, and of potassium chloride, preferably in equal proportions, It has been found that the results in terms of cooling achieved with the use of this mixture are better than those achieved with the use of the individual substances.

It is also pointed out that urea and potassium chloride, like sodium thiosulphate, are free of the disadvantages discussed above with reference to ammonium nitrate.

In a second variant of the invention, the second component comprises a predetermined quantity of sodium iodide, suitably provided in the second compartment 14.

EXAMPLE An example of the use of a self-cooling container formed in accordance with the invention is given below, indicating specifically the quantities of components used and the results obtained in terms of cooling.

A container formed as described above, comprised an aluminium receptacle filled with 40 ml of a beverage (for example, coffee or tea). 40g of water and 65 g of sodium thiosulphate pentahydrate were provided in the first and second compartments, respectively.

When the reaction was triggered in the manner described above, the beverage contained in the receptacle 3 was cooled by 13°C from an initial temperature of 20°C, within a period of 40 seconds.

However, since the solubility of sodium thiosulphate in water is dependent on temperature, the degree of cooling achieved varied according to the starting temperature of the container.

The degrees of cooling noticed in the beverage with the use of containers identical to that mentioned above, but starting from different temperatures are given in the following table. Initial temperature (°C) 25 30 35 Degree of cooling (°C) 15 18 20 The present invention thus solves the problem discussed above, at the same time offering many further advantages, amongst which is the fact that the components of the endothermic reaction can be considered completely safe both from the health and hygiene point of view and from the safety point of view, thus enabling the containers in which they are provided to be used with complete confidence.

A further advantage is that the components are available commercially at low cost.