DESCRIPTION

The present invention relates to an inflatable life jacket. In particular, the present invention concerns an inflatable life jacket capable of producing heat in order to increase the probability of survival in case of hypothermia.

As is widely known, in the case of boating accidents the greatest injuries to people are not caused by the accident itself, but by the consequences of remaining at length in cold sea or ocean waters.

In fact, the human body functions well at temperatures between 36.5°C and 37.5°C. If the temperature inside the human body were to drop to values below than 35°C, the heart, the nervous system and other vital organs would be unable to function correctly, quickly causing death.

Watercraft and aircraft are equipped with life jackets able to be inflated (automatically and/or manually) in order to ensure that the wearer floats, in the case of shipwreck, sea landing or accidental immersion in sea or ocean waters. In this way, it is possible to prevent death by drowning but, as mentioned previously, even if a human body floats, it cannot escape death by hypothermia, if rescue is not immediate.

For this reason, there have been proposed life jackets provided with battery powered heating means. However, batteries are subject to corrosion, above all in a marine environment, so that their use is incompatible with watercraft as they would require excessive maintenance operations.

There are also known life jackets comprising materials capable of accumulating latent heat, which is released, through activation, in case of emergency. An example of these life jackets is described in the patent US 8,727, 825. The problem linked to these life jackets consists in the impossibility to modulate the heat produced; in fact, the latent heat transferred by these materials through solidification is excessive at first and then quickly disappears. In this way, heat is produced for a short period of time and then disperses very quickly. In fact, the heat flow between two objects is proportional to the difference in temperature between them. This means that if heat is produced very quickly, it will also disperse much more rapidly. The result is that there is little probability of increasing survival, as they do not greatly prolong the life of shipwrecked people.

Therefore, there has been evaluated the possibility of using life jackets provided with chemical reagents which, activated through contact with water, give rise to exothermic reactions capable of heating the human body. However, among the numerous chemical reagents capable of producing heat in contact with water, very few are suitable for the present use.

In fact, the Applicant has studied numerous reagents, verifying the impossibility or inadvisability to use many of them. The Applicant started to investigate in the search for a reaction capable of producing a high total amount of heat that could be modulated in time. In fact, activating a strong acid with water would cause a highly exothermic reaction, but it would give off too much heat too quickly, hence not guaranteeing a suitable duration of action. Therefore, the Applicant thought of using a controlled chemical reaction between a metal and an acid.

As is known in the literature, the energy produced by a redox reaction between a metal and an acid depends greatly on the type of metal and on the acid utilized. In general, the smaller the reduction potential of the metal is, the more energy will be produced following the release of hydrogen. One of the metals that has a greater reaction enthalpy is aluminium. Therefore, the Applicant has studied the reactions of aluminium with some protic acids, i.e., acids having dissociable hydrogen atoms such as H ⁺ ions.

The general reaction of aluminium with protic acids takes a course that can be represented by the following chemical equation: 126 kcal/mol

Theoretically, this reaction progresses releasing around 4800 kcal of thermal energy for each kilogram of metal utilized. However, the efficiency of this process is a function of the acid utilized. For example, the use of hydrochloric acid effectively released the energy indicated above, while the reaction with sulphuric acid leads to the formation of aluminium sulphate that is difficult to remove from the metal. This blocks the reaction and compromises its efficacy.

Moreover, although some of these reactions with protic acids are highly effective, they have risks for the user. In fact, the most common protic acids are generally marketed as more or less concentrated aqueous solutions, highly corrosive and dangerous to handle.

Based on these considerations there is clearly the need to provide a life jacket that allows the aforesaid problems to be eliminated or minimized.

The aim of the present invention is therefore to produce a heating life jacket that overcomes the aforesaid problems related to life jackets of known type. In particular, within this aim, an object of the present invention is to provide a life jacket that, besides ensuring that people who have accidentally fallen into the sea float, prevents their death by hypothermia.

Another object of the present invention is to provide a heating life jacket that is effective and at the same time innocuous for the user.

Yet another object of the subject matter of the present invention is to provide a heating life jacket capable or releasing heat in a controlled manner and that is, at the same time, resistant to corrosion in marine environments.

The present invention therefore relates to an inflatable life jacket, comprising at least a first inflatable chamber and a second chamber, adjacent to said first chamber, characterized in that said second chamber comprises in its inside at least one acid resin and at least one metal having an electrical potential lower than the hydrogen standard reduction potential, said second chamber being provided with unidirectional means able to allow the entry of water inside it.

In other words, the life jacket according to the invention comprising a chamber provided with an acid resin and a metal and with unidirectional means for the entry of water inside it allows automatic triggering of a controlled exothermic reaction when the user is immersed in water.

In this way, besides floating due to the presence of the first inflatable chamber, the user is heated by means of production of a suitable amount of heat for a prolonged time and thus avoids suffering from phenomena of hypothermia.

The presence of an acid resin and of a metal having an electrical potential lower than the hydrogen standard reduction potential makes the life jacket of the invention effective and safe. In fact, these reagents are innocuous, besides triggering controllable reactions. In fact, ion exchange acid resins, above all strong acid resins, have groups very similar to those of sulphuric acid (i.e., sulphonic groups) but linked to a three-dimensional polymer structure that makes it possible to obtain highly porous solid particles that can be handled very safely as they do not cause problems of corrosion. At the same time, in water these particles release H+ ions in the same way as sulphuric acid. These features mean that these acid resins are extremely suitable to be introduced into the second chamber of the life jacket of the invention guaranteeing a long shelf life of the product, becoming active only when immersed in water.

Therefore, the combination of the aforesaid features makes the life jacket effective, safe and resistant.

Moreover, the presence of a metal with the aforesaid features makes it possible to regulate the reaction duration and hence control the release of heat. In fact, based on the physical dimensions of the metal (larger or smaller grains), the reaction lasts for a longer or shorter amount of time, releasing heat more slowly or more quickly. In fact, the metal reacts only on the surface and only after having consumed all of the first surface layer does it start to consume the second layer, and so on, for a longer duration.

Preferably, said second chamber is also provided with means for the discharging of hydrogen from it. As mentioned, the reaction triggered inside the second chamber also produces gaseous hydrogen which should be removed from said second chamber; therefore, if the unidirectional means for the entry of water do not allow the discharging of gas, then these means for the discharging of hydrogen should necessarily be provided. Instead, if the unidirectional means able to allow the entry of water inside it and not its discharging, were able to allow the discharging of gas, then these means for the discharging of hydrogen could be provided to allow a faster discharge thereof.

Preferably, said at least one acid resin is selected from the group consisting of: sulphonic resin, phosphonic resin and carboxylic resin. These resins have the advantage of being solid and easy to handle products, capable of releasing H+ ions once in the water. The acid strength can be modulated utilizing different functional groups and is decreasing passing from sulphonic, phosphonic and carboxylic resins.

Even more preferably, said resin is a strong acid sulphonic resin that allows a very low pH to be reached, such as sulphuric or hydrochloric acid.

In accordance with preferred embodiments, the metal is selected in the group consisting of: aluminium, lithium, potassium, sodium, magnesium, zinc, barium, chromium, iron, lead, tin, nickel, cobalt, titanium, selenium, cadmium, manganese, vanadium, strontium, zirconium, calcium, rubidium, niobium, indium, germanium and molybdenum. These metals react spontaneously with the H+ ions released by the ion exchange resin generating heat.

Preferably, this metal is lithium, potassium, barium, strontium, calcium, sodium, magnesium, aluminium, zirconium or manganese as they are capable of generating more heat. Even more preferably, the metal is selected from aluminium, magnesium or calcium as they are safer to handle.

Advantageously, the second chamber also comprises inside it a water-soluble salt. This feature makes the life jacket also suitable for use in fresh waters. In fact, the oxide of the metal that forms as the reaction progresses tends to deposit on the surface of the metal in this way isolating the lower layers and in fact quenching the reaction. This problem is solved by forming a soluble salt of the metal by means of a salt with an anion compatible with the metal. In fact, in this way the soluble salt of the metal moves away in the water allowing the lower layers to cause the reaction to progress. This is not necessary in salt waters as the sodium chloride naturally present in the sea water is sufficient to dissolve the metal releasing the lower layers.

Preferably, said salt consists of a metal cation and an anion selected from the group consisting of: chloride anion, fluoride anion, bromide anion, iodide anion, sulphate anion, carbonate anion, nitrate anion, phosphonate anion, phosphate anion and acetate anion. These have proven to be more effective for the aforesaid purpose.

Even more preferably, said salt is a chloride such as sodium, calcium or potassium chloride. The presence of chloride in particular makes the ionic metal that is released by the reaction between the metal and the acid resin extremely soluble. Therefore, chloride allows complete conversion of the metal facilitating chemical transport phenomena that ensure total release of the heat contained in the chemical structure of the reagents.

According to preferred embodiments, said unidirectional means to allow the entry of water comprise a semipermeable membrane. It is simple and effective for the specific use.

The life jacket can also comprise a third inflatable chamber adjacent to said second chamber and opposite to said first inflatable chamber. In this way, as the second chamber in which heat develops is interposed between two chambers containing gas, it is more thermally insulated and retains heat for longer.

Preferably, the first chamber and/or the third chamber are equipped with at least one inflation system with carbon dioxide. This system causes the chamber to inflate automatically and/or manually in contact with water.

Advantageously, said first chamber and/or said third chamber is provided with at least one tube able to connect the inside of said first chamber and/or said third chamber with the external environment, said tube being provided with a valve suitable to allow the entry of air inside said first chamber and/or said third chamber but to prevent its discharging. This tube allows the user to further inflate the pneumatic chambers, by blowing into the tube, and hence to float better. Otherwise, in case of damage to the inflation system, this tube allows the user to float.

In accordance with the preferred embodiments, the second chamber is positioned so as to be in contact with the user and the first chamber is positioned so as to be in contact with the external environment, during use. In this way, the first chamber insulates the second chamber from the cold waters, preventing heat loss.

Advantageously, the life jacket further comprises a container containing a water and glucose solution, suitable to be sucked by the user, so as to receive further energy, and hence heat, for increased autonomy.

Preferably, the life jacket also comprises one or more inflatable aids connectable to said second chamber. In this way, it is possible to exploit the gas produced by the reaction of the acid resin with the metal to inflate a further rescue element such as a buoy or a raft.

In the present context, the words “internally”, “externally”, “above”, “below” and “laterally” are defined in relation to the user. Therefore, for example “internal chamber” refers to the chamber in contact with the user.

Further features and advantages of the present invention will be apparent from the following description of preferred, but non exclusive, embodiments of a life jacket according to the invention, illustrated by way of example in the accompanying drawings, wherein:

Fig. 1 shows a schematic front perspective view of a first embodiment of life jacket according to the present invention;

Fig. 2 shows a schematic view of the same life jacket as Fig. 1, worn by a user;

Fig. 3 shows a partially transparent schematic side view of Fig. 2;

Fig. 4 shows a schematic view in longitudinal section of a portion of the life jacket of Fig. 3;

Fig. 5 shows a partially sectional schematic view of a life jacket according to a second embodiment of the invention, during use;

Fig. 6 shows a schematic view in longitudinal section of a portion of life jacket according to a third embodiment of the invention;

Fig. 7 shows a schematic view in longitudinal section of a portion of life jacket according to a fourth embodiment of the invention;

Fig. 8 shows an enlarged detail of Fig. 7; and

Fig. 9 shows a partially sectional schematic view of a life jacket according to a fifth embodiment of the invention, during use.

With reference to Figs. 1 to 9, a life jacket according to the present invention is indicated as a whole with the reference number 1.

The life jacket 1 comprises at least a first inflatable chamber 2 and a second chamber 3 adjacent to said first chamber 2. The first chamber 2 is intended to be inflated during use in order to ensure that a user 4 floats, while the second chamber 3 is intended to heat the user 4 during use, to prevent hypothermia.

To this end, said second chamber 3 comprises in its inside at least one acid resin and at least one metal having an electrical potential lower than the hydrogen standard reduction potential, so as to oxidize in contact with the hydrogen ions released by the acid resin in contact with water. The redox that takes place in the second chamber 3 produces thermal energy utilized to heat the user 4.

The second chamber 3 is for this reason provided with unidirectional means 5 able to allow the entry of water inside it, but prevent its discharging. Therefore, the direction of the water is the one indicated by the arrow in Fig. 4. These unidirectional means 5 preferably comprise a semipermeable membrane that prevents the discharge of water but not of gas. In this way, the hydrogen produced by the redox reaction in question is able to discharge from the second chamber 3 allowing the entry of a larger amount of water.

Preferably, the second chamber 3 is also provided with means for the discharging of hydrogen from it. It facilitates more rapid discharge of hydrogen, preventing the pressure inside the second chamber 3 from being too high and facilitating the entry of larger amounts of water and hence a greater energy reserve.

According to an alternative embodiment of the invention, the unidirectional means 5 for the entry of water inside the second chamber 3 comprise a semipermeable membrane that prevents the discharge of fluids, whether liquids or gases. In this case, the presence of the means for the discharging of hydrogen is essential for removal of the hydrogen that has formed.

This hydrogen discharged from the second chamber 3 can be exploited to inflate auxiliary rescue means, thanks to its very low density. Therefore, the life jacket 1 can comprise one or more inflatable aids connectable to said second chamber 3. In particular, they can comprise a signalling buoy 6 and/or a raft 7 (see Fig. 6). To give an idea of the amount of gas produced by the reaction, one can consider that, at the end of the complete reaction, 100 grams of aluminium release over 100 litres of gas in ordinary conditions. This high amount could be exploited to inflate the first chamber 2, if regulations were to permit this in the future.

In Figs. 4, 6, 7 and 8 the water is illustrated by means of wavy horizontal or vertical lines, while the gas used to inflate the inflatable chambers (first chamber 2 and optional third chamber 8), typically carbon dioxide, is illustrated by means of squiggles that are similar to the number 6. In Fig. 5, the water inside the second chamber 3 is represented by small squares. In Fig. 6, the gas produced by the redox reaction that takes place inside the second chamber 3, i.e., hydrogen, is illustrated by means of circular bubbles.

Preferably, said at least one acid resin is selected from the group consisting of: sulphonic resin, phosphonic resin and carboxylic resin. More preferably, it is a strong acid sulphonic resin. These resins have the feature of being in the form of polymer particles consisting of polystyrene variously cross-linked with divinylbenzene, functionalized with sulphonic groups. They are solid and easily handled without problems of danger.

In accordance with preferred embodiments of the invention, said at least one metal is selected in the group consisting of: aluminium, lithium, potassium, sodium, magnesium, zinc, barium, chromium, iron, lead, tin, nickel, cobalt, titanium, selenium, cadmium, manganese, vanadium, strontium, zirconium, calcium, rubidium, niobium, indium, germanium and molybdenum.

Preferably, this metal is lithium, potassium, barium, strontium, calcium, sodium, magnesium, aluminium, zirconium or manganese.

Even more preferably, the metal is selected from aluminium, magnesium or calcium.

Preferably, the metal grains have a size ranging from a few nanometres up to chips in the order of centimetres and larger. Even more preferably, the metal grains have a size ranging from one micron up to tens of millimetres.

Preferably, the grain size distribution can be very wide to allow different reaction speeds (and hence heat release), increasing the possibility of simple modulation of the heat release time. Even more preferably, grains of different size can be mixed for even more accurate control of the heat release speed.

To increase the shelf-life of the life jacket, the resin and the metal grains are in solid form in dry condition. Preferably, resin and metal grains are loaded in distinct positions inside the chamber 3 so that they are not in contact. Even more preferably, the two solids are protected separately by a water-soluble polymer film, for example based on: polyvinyl alcohol, polyvinylpyrrolidone, cellulose, modified cellulose, starch, modified starch, etc.

In accordance with some embodiments, the second chamber 3 comprises in its inside also a salt soluble in water. As mentioned, this salt allows removal of the metal oxide from its surface, in non-saline environments (such as in lake or river waters), so that the reaction is not extinguished. This salt is preferably a chloride; even more preferably, sodium or calcium chloride. However, it can also consist of a metal and non-metal cation (such as a quaternary ammonium salt), and of an anion selected from the group consisting of: chloride anion, fluoride anion, bromide anion, iodide anion, sulphate anion, carbonate anion, nitrate anion, phosphonate anion, phosphate anion, acetate anion. Even more preferably, this salt soluble in water can be protected by a water-soluble polymer film for example based on: polyvinyl alcohol, polyvinylpyrrolidone, cellulose, modified cellulose, starch, modified starch, etc....

The life jacket 1 preferably has the form of a vest, as visible in Figs. 1 and 2, so as to be save space when not in use, but to heat the vital organs. However, alternative embodiments with sleeves could be provided. These sleeves could be made of thermal material or be provided with circuits for circulation of hot water and/or gas. The life jacket 1 comprises two portions: one front and one rear, which are connected and preferably symmetrical with respect to the body of the user 4. In this case, also the first chamber 2 and the second chamber 3 are provided with a front portion and a rear portion which are pneumatically/hydraulically connected, as can be seen in the figures. In other words, the first chamber 2 and the second chamber 3, when not utilized, define two superimposed layers defining a hole for the head of the user 4 to pass through.

Advantageously, the second chamber 3 is positioned internally, i.e., so as to be in contact with the user 4 and the first chamber 2 is positioned externally, i.e., so as to be in contact with the external environment during use, as visible in Fig. 5. In this way the heat produced is optimized as the heating chamber, i.e., the second chamber 3, is in direct contact with the user 4 and is insulated from the external environment by the first chamber 2.

The first chamber 2 and the second chamber 3 can have the same shape and be positioned so as to be parallel and superimposed, as in the case illustrated in Fig. 3. However, to minimize heat loss, the first chamber 2 has a concave shape so as to partially accommodate therein the second chamber 3, as visible in Fig. 5. In fact, in this way the second chamber 3 is insulated with respect to the environment not only externally, but also from above and below.

In accordance with preferred embodiments, shown in Figs. 3, 4, 6 and 7, the life jacket 1 also comprises a third inflatable chamber 8 adjacent to said second chamber 3 and opposite to said first inflatable chamber 2. In these cases, it is positioned internally, i.e., so as to be in contact with the user 4 during use so as to further insulate the second heating chamber 3.

The life jacket 1 illustrated in the embodiment shown in Fig. 9, although not provided with a third chamber 8, has a first chamber 2 having a shape such as to completely contain the second chamber 3 inside it. Therefore, it is equivalent to the embodiment of Fig. 3 (provided with three chambers), with the advantage of completely insulating the second chamber 3, i.e., from above, from below, from the front and from the back.

In accordance with preferred embodiments, the first chamber 2 and/or the third chamber 8 are provided with at least one inflation system with carbon dioxide. It is preferably of automatic type, but can also be manual, or have both activation mechanisms. Activation consists, in both cases, in the perforation of a high pressure bottle containing CO2 (carbon dioxide) and in the passage of the gas inside the first inflatable chamber 2 and optionally the third chamber 8. In the case of automatic activation, there is provided an element that in contact with water triggers the inflation action of the chamber or chambers. The most widely used and economical type of element consists of a salt tablet, which dissolving (a few seconds after immersion in water) releases a spring operated striker that perforates the bottle and injects the carbon dioxide inside the first chamber 2 and/or the third chamber 8. In case of manual activation, perforation of the bottle takes place by pulling a cord that releases the striker. As these are known inflation systems, they will not be described in greater detail.

Preferably, the first chamber 2 and/or the third chamber 8 is provided with at least one tube 9 able to connect the inside of said first chamber 2 and/or said third chamber 8 with the external environment, as visible in Figs. 1, 2 and 7. The tube 9 is provided with a valve 10 (visible in Fig. 8), which is suitable to allow the entry of air inside said first chamber 2 and/or said third chamber 8 but to prevent its discharging. The purpose of this tube 9 is to inflate the life jacket 1, if the aforesaid inflation system with carbon dioxide were to be damaged or missing.

In accordance with the embodiment illustrated in Figs. 7 and 8, the life jacket 1 also comprises a container 11 containing a water and glucose solution. This solution is represented by small diamonds in these figures. The container 11 is preferably positioned between the first chamber 2 and the second chamber 3, so as to further limit heat loss and at the same time guarantee heating of the sugar solution. Alternatively, the container 11 is positioned in the third chamber 8, when present, or in the first chamber 2. This solution is accessible to the user 4 by means of a suction tube, such as a drinking straw. Preferably, this suction tube is the same tube 9 for inflation of the first chamber 2 and/or third chamber 8. It is advantageously arranged so as to allow discharge of the sugar solution when the user 4 creates a negative pressure through suction, and passage of air in the opposite direction when the user 4 creates pressure through blowing, as can be seen in Fig. 8. In this figure, the arrows with a continuous line indicate the direction of the sugar solution, while the arrow with a dashed line indicates the direction of the gas blown by the user 4.

As mentioned previously, the sugar solution serves to further increase the thermal energy available for the user 4 so as to increase their chance of survival in the water. In fact, the ingestion of 100 grams of sugar releases 400 kcal (amount of energy comparable to the amount released by the chemical reaction of the device of the invention) into the human body. The container 11 is preferably suitable to contain around 200 ml of sugar solution. In fact, this amount is suitable to dissolve 100 g of glucose.

Following a shipwreck, the user 4 may have lost their sense of direction and be in a state of confusion, and therefore it is preferable to position the tube 9 in a position such that it is close to the mouth of the user 4 during use, so as to allow natural suction, as shown in Figs. 1 and 2. The use of a sugar solution at 50% makes it possible to obtain a viscous solution capable of limiting any long term losses of this solution, during the life of the device. Moreover, a solution of this kind allows, through substrate inhibition of the sugar, the prevention of any contamination by bacteria, yeasts, fungi and/or moulds, ensuring a very long shelf life of the life jacket 1.

The life jacket 1 is preferably made of mouldable plastic materials such as polyolefins, PP and/or PE, so as to obtain a low cost of the finished product and very easy composition of the device, but they can also be made of polymer plastic materials utilized for wetsuits, such as neoprene.

The life jacket 1 is also provided with closing means 12, able to secure the life jacket 1 to the body of the user 4 and to block it in position, in a known manner.

For the purpose of providing further clarifying information, the description of a possible operating mode of the life jacket 1 is set forth below.

The particles of acid resin and the metal powders selected are inserted into the second chamber 3 of the life jacket 1 in dry conditions, i.e., in the absence of water. Preferably, acid resin and metal grains are loaded into distinct positions inside the chamber 3 so that they are not in contact. Even more preferably, the two solids are protected separately by a water soluble polymer film, for example based on: polyvinyl alcohol, polyvinylpyrrolidone, cellulose, modified cellulose, starch, modified starch, etc.

In emergency conditions, when a user 4 provided with life jacket 1 accidentally ends up in the sea, the unidirectional means 5 allow the passage of water from the outside toward the inside of the second chamber 3. The entry of water in this chamber triggers the hydration reaction of the H+ ions, which reacting with the metal, release heat and gas. This exothermic reaction continues until the reagents are exhausted. The heat produced is used to heat the body of the user 4, while the gas is emitted into the atmosphere or exploited to inflate a signalling buoy 6 or other auxiliary devices. Simultaneously, the inflation system causes the automatic entry of carbon dioxide into the first chamber 2 and optionally into the third chamber 8. Pneumatic filling of these chambers causes insulation of the second chamber 3, which is the chamber in which the reaction takes place and consequently the chamber in which heat develops.

In this way, the user 4, whether conscious or unconscious, floats and their vital organs are heated, so as to prevent death by drowning and/or by hypothermia, while waiting to be rescued. If the life jacket 1 were also provided with the container 11 for the sugar solution, the resistance of the user 4 in the water would be further increased by means of its suction by the user 4.

Some examples of tests carried out by the Applicant aimed at optimizing the exothermic reaction that takes place in the second chamber 3 of the life jacket 1 of the present invention shall now be described. EXAMPLE 1

The first series of experiments were carried out by reacting 15 grams of sulphonic resin Dowex (www.hytekintl.com) with 10 grams of aluminium purchased from Merck (11009 Aldrich Aluminum), size 10-200 micron, in a 1 litre beaker. After a short period of time (around 4 minutes) of hydrogen development a progressive decrease in the production of gas was observed, followed by complete quenching of the reaction, after around 5 minutes, with evident amounts of unreacted metal. The experiment proves the problem inherent to the production of aluminium salts that, depositing on the surface of the metal, block its reactivity. EXAMPLE 2

A solution of synthetic sea water was prepared by dissolving 30 grams of sodium chloride for each litre of distilled water. The same experiment indicated above was carried out utilizing synthetic sea water. In this case, the corrosion reactions of the metal remained active developing hydrogen for over 7 minutes and leading to the complete consumption of the metal utilized. The increase in the temperature of the water (in the experiment the losses were not minimized) made it possible to estimate an energy release of around 45 kcals per 10 grams of aluminium utilized.

EXAMPLE 3

The same reaction set forth in experiment 2 was carried out, modifying the size of the metal grains. In particular, aluminium grains with a larger diameter with respect to the previous experiment were used, i.e., diameter below one millimetre (518573 Aldrich Aluminium, size 100-1000 micron). The larger size led to complete consumption of the metal in 17 minutes, confirming the possibility of controlling energy release over time.

RESULTS

Examples 1 and 2 set forth above show how in the presence of sea water, it is not necessary to provide a water soluble salt, while if the life jackets 1 are utilized in fresh waters it is preferable also to use a water soluble salt, with the aim of maximizing exploitation of the reagents.

Example 3 shows how it is possible to control and modulate energy release by the life jacket 1. This result, predictable with the shrinking core model and confirmed by the experiment, makes it possible to provide a mixture of metal particles to be inserted into the life jacket 1 such as to be able to define in advance the heat release profile by the second chamber 3. In fact, insertion of extremely fine particles allows a rapid release of heat in an amount proportional to the mass of said particles. Instead, larger particles require longer release times, obtaining controlled release of heat for a longer time (controlled temperature maintenance). As can be seen from the description provided, the technical solutions adopted for the life jacket 1 according to the present invention allow the aims and objects set to be fully achieved. In fact, the life jacket 1 according to the invention allows the user 4 to float and be heated, preventing their death by hypothermia and simultaneously being effective, innocuous and resistant to corrosion.

The life jacket 1 according to the invention also makes it possible to control of the amount of heat released over time by the chemical reaction activated automatically by contact with water.

The life jacket 1 thus conceived is susceptible to numerous possible variants, all falling within the scope of the present invention. For example, the life jacket 1 could be integrated inside an immersion suit utilized for water sports. The life jackets 1 could also have an asymmetrical configuration, i.e., the life jackets 1 could be provided with a second chamber 3 positioned only at the front of or only at the rear of the body of the user 4.

The materials employed and the sizes and contingent shapes may be any according to requirements and to the state of the art.