WO2002102921A1

WO2002102921A1 - Refrigeration unit in particular for application in cryotherapy or for food conservation

Info

Publication number: WO2002102921A1
Application number: PCT/FR2002/002126
Authority: WO
Inventors: Michel Bordage; Michel Dixmier
Original assignee: M.D.I.C.
Priority date: 2001-06-19
Filing date: 2002-06-19
Publication date: 2002-12-27
Also published as: EP1399522A1; WO2002102921A8; FR2826107A1

Abstract

The unit comprises a sealed flexible envelope enclosing a composition containing water, a thickening agent and an agent for lowering the freezing point of said composition. The unit is characterised in that the thickening agent comprises one or more hydrocolloids and the agent for lowering the freezing point is present in such a proportion as to give a fusion phase at an effectively constant temperature, not lower than about -10 DEG C, in such a manner that, during the fusion phase, the composition is malleable.

Description

"Refrigerating article in particular for an application in cryotherapy or for the conservation of food"

The present invention relates to a refrigerating article, that is to say capable of restoring cold to an environment. More specifically, it is an article which must be cooled for a defined time before use, which then heats up by restoring cold to an environment and which can be reusable for a new cooling / heating cycle. The scope of this article is that of cryotherapy, especially in all cases where the application of cold relieves pain (headache, toothache, migraine, muscle and / or inflammatory pain etc.) or promotes resorption of hematomas or edemas. The article according to the invention can also be used simply for the purpose of cooling, in particular for an athlete or for any person, working or not, exposed to a heat source.

The field of application can also be that of the conservation of cooked or raw food.

US Patent 3,545,230 Union Carbide proposes a refrigerating article which uses the latent heat of fusion of a liquid passing from the frozen state to the thawed state. During this melting phase the temperature remains constant. The article is characterized by at least one layer of an insoluble hydrophilic gel (retains its gel form up to 35 ° C.) packaged in an envelope made of flexible waterproof material. No specific polymer for the hydrophilic gel is mentioned in the document. A flexible inert substrate is introduced into the gel, for example a set of fibers, a woven or nonwoven material or a flexible matrix of polymers (polyesters, polyethylene or cellulose). The substrate constitutes a reinforcement for the thawed gel so that the article can marry any geometric shape and keep it. Furthermore, it is recommended to obtain good flexibility of the article in the frozen state to produce a device comprising several layers, in particular up to twenty layers of a few millimeters each, each layer being separated by an inert flexible film. This device is advantageous insofar as it recommends the use of a gel form which is stable at room temperature and therefore does not run the risk of leaking if the external envelope is pierced. On the other hand, to obtain the flexibility properties, the manufacture is complicated with the introduction into the gel of the reinforcing substrate and the production of several layers.

To give flexibility to the article at the temperature of use, another solution is proposed in US patent 3,885,403 from Nortech Laboratories. It consists in removing, at the temperature of use, the frozen state of the gel by introducing into the gel a high concentration of an agent lowering the freezing point below the temperature of use, more particularly glycerol and / or propylene glycol (23 to 50% by weight relative to the total weight of the gel). In this case, the restitution of the cold is done only by heating the gel and not by taking advantage of the latent heat of fusion of the liquid contained in the gel. The duration of use is therefore shorter. The major drawback further lies in the fact that, to overcome this drawback, the article must be stored at very low temperature (-18 ° C. average temperature of a freezer) in order to have the longest possible heating phase, and that at such a low temperature, the user risks being burned by the cold. As an example of a thickening agent, the patent cites a synthetic carboxy-vinyl polymer, Carbopol 940®.

Another solution is also proposed in patent application EP 0123949. It consists in manufacturing pieces of gel having an elasticity comparable to rubber and not sticking together at low temperature, and in packaging them in a flexible waterproof envelope. The movement of the pieces relative to each other gives flexibility to the article. This solution has the disadvantage of the heaviness of the manufacturing method. Yet another solution is proposed in the patent application

FR 2 719 599, which consists in using inside a flexible waterproof envelope a composition based on a hydrogel, in particular a crosslinked polyacrylate, consisting of granules which are swollen with water, which are distinct each other and which have properties of flexibility and elasticity at room temperature.

In addition, a thermal cushion is marketed by the company 3M under the name of ColdHot pack®. It can be used in cryotherapy or thermotherapy. It includes a flexible envelope made of thick plastic material containing a viscous solution, based on cellulose and containing a high concentration of propylene glycol. On leaving the freezer (storage temperature of approximately -8 ° C), the composition inside the cushion is cooled but is not frozen and reaches an ambient temperature of approximately 30 ° C in 3 hours. In practice, to increase this period of use, the user will store the cushion in the freezer at -18 ° C so that it reaches a lower temperature and heats up more slowly. However at this temperature, it is found that the composition inside the cushion is frozen and has lost all its flexibility. The cushion is as hard as an ice cube and absolutely not malleable. In addition, the user here too risks being burned by the cold. It is also necessary to use a protective cover, which also constitutes an additional barrier to the transfer of cold.

A headband against migraine is also sold under the brand Cryomed® consisting of an envelope which is permeable to water and which contains polyacrylate crystals. To use the strip, it must first be wetted to swell the polyacrylate crystals, which makes it possible to obtain a gel, then store the strip in contact with a cold source. Thanks to the permeability of the envelope, the cold restitution mechanism here also includes a phase of evaporation of the water contained in the gel particles. On leaving the freezer, we see that the strip is flexible but has the following drawbacks: - an unpleasant feeling when touched due to the presence of crystals, probably ice; - A risk of contamination of the gel by bacteria given the permeability of the envelope; - A risk of burns by the cold even at the exit of the freezer, because the outside of the envelope, wet for the swelling of the gel, contains ice crystals.

In addition, there is a risk of bursting of the envelope when if the gel swells too much.

The aim of the present invention is to overcome in particular all of the drawbacks which have just been mentioned, namely:

- the risk of cold burns, in particular by wanting to increase the duration of use by storing and applying the article at very low temperatures;

- a procedure that is too complicated to achieve the flexibility properties of the article from the start of its use;

- contact with the skin of the cryogenic composition which also leads to the risk of burns, contamination if the solution develops bacteria etc.

The primary characteristics sought for the article according to the invention are thus:

- At a defined temperature of use, at which the user does not risk being burned, the article must be very quickly usable, that is to say flexible, malleable, in order to be able to marry any geometric shape;

- it must have a long service life; and

- it must be simple to manufacture.

It proposes a refrigerating article suitable for restoring cold to an environment for an application in particular in cryotherapy or for the preservation of food, said article comprising a flexible waterproof envelope containing a composition comprising water, a thickening agent and an agent for lower the freezing point of said composition, characterized in that: - the thickening agent comprises one or more hydrocolloids; and

the agent for lowering the freezing point is present in a proportion such that the composition has a melting range at a substantially constant temperature which is not less than -10 ° C. approximately, so that in this melting range the composition is malleable.

The invention resides in the fact that one uses:

- one or more hydrocolloids; - some water; and

an agent for lowering the freezing point, in controlled proportions so that the composition inside the envelope, in the frozen state and at the melting temperature, remains flexible, even malleable and in addition that said melting temperature is not less than -10 ° C., an estimated lower limit negative temperature at which the user is not likely to be burned by the cold. Preferably, a melting range is chosen at a temperature which is not less than -5 ° C.

The choice of a hydrocolloid as thickening agent is notably linked to the fact that hydrocolloids are capable of absorbing a very large amount of water. In addition, the texture obtained after absorption of water at room temperature is very pleasant to the touch, ranging, depending on the type of hydrocolloid and its content, from the viscous solution which can flow, to the gel forming a continuous band more or less flexible than we can cut. A composition based on hydrocolloid (s) without agent for lowering the freezing point is in the frozen hard state and absolutely not malleable, therefore unusable directly after storage. The presence of a controlled percentage of agent lowering the melting point, has the effect of giving the composition very quickly over time, once the melting phase has started, despite this frozen state, a texture comparable to that which presents the composition at room temperature. For example, a strong gel based on Agar, in the frozen state, will be fragmentable at the melting temperature and can be kneaded at the first use to form small pieces inside the envelope. gel moving relative to each other, this gives the article flexibility allowing it to marry a complex shape and a soft texture pleasant on contact with the skin. A weaker frozen gel will form a continuous band retaining its flexibility at melting temperature. Thus, the nature and the content of the hydrocolloid can be adapted according to the texture sought for the article.

Among the hydrocolloids, preference will be given to polysaccharides, in particular of marine origin, such as Agar and PAginate, which are non-toxic natural products and which, as will be seen below, make it possible to produce an article having a good compromise between texture adequate, holdover time and melting temperature.

The agent for lowering the freezing temperature is preferably glycerol and / or propylene glycol which are miscible with water. The glycerol is preferably chosen in particular because the water / glycerol mixture makes it possible to better dissolve most of the hydrocolloids and moreover with a low concentration of glycerol. In addition, glycerol is a non-toxic product.

According to the invention, the amount of freezing point lowering agent has an influence on the texture of the gel frozen at the melting temperature. Preferably, in the case of glycerol, the proportions will be from 5% to 20% by weight relative to the total weight of the composition, with a preferred proportion of 10% making it possible to obtain the best compromise between the presence of a phase of fusion and an optimal duration of effectiveness, and an adequate texture for the composition. According to the invention, a sealed envelope is used so that, on the one hand, the risks of external contamination are eliminated and, on the other hand, the article is produced once and for all without needing to be wet with each new use.

For the waterproof envelope, a synthetic material is preferably chosen which has elasticity in at least one direction, more preferably in two directions so that the article can best conform to a complex shape. To optimize heat exchange with the environment, the thickness of the envelope will be that of a film. By way of example, a stretch film can be used according to the invention, in particular 100% polyethylene or 100% octene 15 or 17 μ.

For certain applications, where for example the contact zone is particularly sensitive or else to improve the softness of the article, an additional external envelope made of a particular material may be provided, like for example elastic cotton fabric (commonly called hospital fabric). The presence of an external envelope of this type does not significantly modify the heat exchanges.

Furthermore, advantageously, an external envelope can be provided in a tissue suitable for receiving and trapping molecules by spraying. Thus, for example, the envelope may advantageously contain drug molecules with local action which will act in addition to cryotherapy. They can also be so-called "well-being" molecules such as natural essences of plants, in particular peppermint or lavender, which are known for their refreshing and decongestant effect.

Furthermore, an antimicrobial agent, such as for example methyl paraben, can be added to the composition.

For fixing the article, it is possible to provide a strip of adhesive of the repositionable type which cannot be altered by the cold, either to close two parts of the article together, or brought into contact directly with the skin of the user using in this case a repositionable adhesive based on natural components.

The manufacture of an article according to the invention is simple. It includes dissolving the hydrocolloid (s) with stirring and optionally by heating, forming a gel or a viscous solution by leaving it to stand at room temperature then cutting or pouring, as the case may be, into an envelope of selected dimensions .

Of course, different embodiments of the invention are possible, which depend on the intended application.

In the medical field, to combat headaches, the shape of the article may be that of a conventional headband. It can also have the form of a compress of any size, which can advantageously be provided with a repositionable adhesive on its contact face. Another embodiment of the invention, new and particularly advantageous, is that of a helmet, with a headband part with at each of its ends a cooling pad intended to be positioned on the temples of the user. We can provide housing to receive the pads so that they are removable and replaceable, so as to be sold separately in the form of refills. This article also has the advantages, compared to a headband or a compress, of being discreet while being hidden under the hair, of being able to be aesthetic, and of using less cryogenic composition.

Also in the medical field, there may be mentioned articles where it is advantageous to combine application of cold and compression or compression, in particular for the ankles, knees, elbows or thighs. These articles may be entirely flexible and elastic, or else, if appropriate, comprise a rigid shell which, according to the invention, will be provided with internal cooling pads located at strategic locations to smoothly adjust the shell, thanks to the soft texture of the pad.

Another example of an application of internal refrigeration covering for a rigid element is that of helmets, in particular of the motorcycle or fire engine type. As other embodiments, mention may be made of standard elements of metal, cardboard or plastic containers.

Furthermore, to facilitate its installation, the internal covering may include on its contact face a repositionable adhesive.

The present invention will be better understood in the light of the following description of embodiments, description made with reference to the drawing in which FIG. 1 is a curve illustrating the heating kinetics of an article according to the invention, with the help of measurements and tests carried out by the Algae Recovery Center (CEVA). Preparation of an article according to the invention in the form of a strip Preparation of the gel:

Reagents used: - Hydrocolloids tested: Polysaccharides:

N ° 1: Agar (SETEXAM, ref FAL2 and ref FHG); # 2: Alginate (S 1,600, SKW Biosystems);

No. 3: Agar FAL2 / Alginate mixture; No. 4: Carrageenans (SKW Biosystems.Satiagel ME5); N ° 5: Guar (Sigma ref G4129); No. 6: Starch (Sigma ref S4126); No. 7: Pectin (Sigma ref P8471); No. 8: Gum arabic (Sigma ref G9752); No. 9: Carboxymethylcellulose (Sigma ref C4888); N ° 10: Xanthan gum (Degussa texturant Systems ref 6012);

A protein: N ° 11: Gelatin (Sigma ref G9382).

- Agent to lower the freezing point: glycerol (French pharmaceutical cooperative: officinal glycerin).

- ultra-pure water Procedure for the preparation of a gel containing 1% of a hydrocolloid chosen from No. 1 and No. 4-11 (identical procedure transposable for a gel based on 0.5% polysaccharide (s)):

• Dispersion with cold magnetic stirring of the hydrocolloid powder at 1.11% (1g dispersed in 89g of water); • Solubilization with magnetic stirring until boiling on a hot plate;

• Maintaining the magnetic boiling for 30 ';

• Addition of glycerol in order to reach a final concentration of 10% relative to the total weight (10g of glycerol added to 90g of non-gelled solution);

• Adjustment of the final hydrocolloid (s) concentration to 1% by gross weight relative to the total weight;

• Pouring onto a Teflon glass plate at a rate of 0.39 g of solution per cm2; • Cooling to room temperature and gelation in 30 to 45 '.

Procedure for the preparation of a gel containing 1% alginate (No. 2

• The preparation of the gel differs from that of the other polysaccharides in that the alginate powder is dispersed cold for 4 hours in the water and glycerol mixture. Procedure for the preparation of a mixed gel, containing 0.5 alginate and 0.5% agar (N ° 3)

• A 1% alginate and 20% glycerol solution is prepared by dissolving the alginate powder in the water and glycerol mixture for 4 hours with mechanical stirring (5g of alginate, 490g of water, 100g of glycerol);

• The agar is dispersed at a concentration of 1.23% when cold for 1 hour (5g of agar and 400g of water); • The agar is dissolved at boiling point with magnetic stirring, with the boiling being maintained for 30 minutes;

• The agar solution is cooled to 60 ° C, the alginate solution is heated to 40 ° C;

• The two solutions are mixed and then water is added to adjust the total mass to 1 kg.

Preparation of the strip: Material used for the envelope: A 100% polyethylene (PE) film 17μ. 3M® glue, ref. 7024 Operating modes:

By cutting (if you have a gel form; this is particularly the case for Agar, the Agar / Alginate mixture, Guar, starch, Pectin,

Gum Arabic, gelatin, Xanthan Gum, caboxymethylcellulose)

We cut a strip of gel, the dimensions being 3.5cm on

28cm (gel mass of 75g).

We cut a piece of polyethylene film 12cm x 32cm in which the gel strip is wrapped and we make a collage on a strip of 1 cm.

By pouring (if we have a viscous solution; this is the case for

Carrageenan and alginate)

The solution is poured into the strip closed on 3 sides then closed on the 4 ^th side after pouring. For reasons of comfort, the headband can then be inserted into an external envelope of hospital tissue. Tests to measure the kinetics of heat transfer on the manufactured strips:

Cold storage of the strips: In the freezer: -7.7 ° C ± 0.4 ° C Conditions for carrying out the measurements:

The strip folded in half is initially packaged in the freezer as well as a Dewar vase used for the transfer of the cold chamber to a measurement chamber consisting of a Dewar vase thermostatically controlled at 32 ° C. 10 minutes before the test, a probe is installed in the cold enclosure under the strip. The assembly, strip and probe, is transferred to the Dewar measuring vessel. The vase is positioned horizontally. It is closed by a waterproof and insulating cap and crimped with parafilm. The probe is connected to a data acquisition center (Consort type) and recording is started. All these operations last only five minutes. The temperatures are recorded every 20s for 6 to 7:30. Exploitation of curves:

An example of a curve and how to use it are presented in Figure 1. The curve highlights a plateau where the temperature is substantially constant as a function of time. It is a thermodynamic characteristic of a change of state. Here, this tray illustrates the fusion of the product. This part of the curve is characterized by a temperature in ° C (intersection between the tangent of the plateau and the temperature axis) and a duration expressed in h. The second part of the curve highlights a rise in temperature to reach the temperature of the enclosure. This part of the curve is characterized by a duration in h and a rate of heating in ° C / h, tangent to the curve at the start of the phase.

Finally, a period of effectiveness can be measured from the strip as the time necessary to reach 30 ° C.

Influence of the glycerol content:

Gel formulation: Alginate 0.5% / Agar 0.5% Envelope: PE film

Freezer storage at -7.7 ± 0.4 ° C until equilibrium

This table shows the influence of the addition of glycerol on the kinetics of the cold. The higher the glycerol content, the lower the temperature of the melting range and the shorter its duration. Thus, up to about 20% glycerol, a melting range is observed. The 40% glycerol product has no melting range and starts at a temperature above 0 ° C.

Measurement of the gel forces at the outlet of the freezer:

Procedure: The gels are poured into different petri dishes 54mm in diameter and stored in the freezer (temperature of -5.7 ° C) until equilibrium. The different boxes are taken out of the freezer at the same time and the gel strength is measured every 5 minutes on a Adamel Lhomargy DY30 traction / compression machine (113.1 mm2 piston). Interpretation of results: A correlation can be made between the malleability of the gel and the fact that a gel force is measurable (the piston of the device penetrates into the gel).

All solid products have very large forces, greater than 80N. These forces cannot be measured with the sensor (it does not penetrate the solidified gel). When thawed, the frost forces become measurable. The glycerol-free test requires 25 minutes of thawing for a gel strength to be measurable. This is not the case with products containing glycerol, the gel strengths of which can be measured after approximately 5 minutes of defrosting. From 20% glycerol, the freezing forces are very low right out of the freezer.

Influence of the type of hydrocoHoid (s):

The headbands are stored in the freezer until balanced Composition: contains 10% by weight of glycerol Envelope in elastic PE film

Composition of the cushion: carboxymethylcellulose and propylene glycol. The holdover time ranges from 4:17 for gelatin to 6:16 for alginate with melting ranges of approximately 2 hours at temperatures between - 5 ° C and + 5 ° C. The choice is then made on the texture sought for the gel. Comparison with the 3M® cushion: the curve does not present a melting plateau but only a heating phase. Compared to frost strong based on Agar FAL2, which gives the best results in terms of duration of effectiveness, the duration of effectiveness of the 3M® cushion is therefore much lower: 3h36 compared to 6 12. Furthermore, at room temperature, the composition of the 3M® cushion is a viscous solution which is unevenly distributed in the envelope and is therefore not suitable for a headband in particular.

Influence of the concentration of hvdrocolloid (s). tested on different polysaccharides:

Influence of the duration of storage in the freezer

Gel formulation: Alginate 0.5% / Agar 0.5%

10% glycerol Envelope: PE film Storage in freezer at -7.7 ° C ± 0.4 ° C

For the formulation studied here, the duration of the melting phase is balanced after 4 hours of freezer storage at a value of around 2 hours. The duration of effectiveness (time to reach 30 ° C) is 5h43 after 4h of storage and reaches 6h00 for the strips stored 8h and 16h.

Tests on two types of external envelopes:

Composition: Agar FAL2 1% and 10% glycerol

Claims

claims

1. Refrigerating article adapted to restore cold to an environment for an application in particular in cryotherapy or for the preservation of food, said article comprising a flexible waterproof envelope containing a composition comprising water, a thickening agent and an agent for lowering the freezing point of said composition, characterized in that: - the thickening agent comprises one or more hydrocolloids; and the agent for lowering the freezing point is present in a proportion such that the composition has a melting range at a substantially constant temperature which is not less than approximately -10 ° C., so that in this melting range the composition is malleable.

2. Refrigerant article according to claim 1, characterized in that the melting range is preferably not less than -5 ° C.

3. Refrigerant article according to claim 1 or 2, characterized in that the agent capable of lowering the melting point of the composition is chosen from propylene glycol and glycerol.

4. Refrigerant article according to claim 3, characterized in that the agent capable of lowering the melting point is the glycerol present in proportions of between 5 and 20% by weight relative to the total weight of the composition, preferably 10% by weight.

5. Refrigerant article according to any one of the preceding claims, characterized in that the thickening agent is a polysaccharide or a mixture of polysaccharides.

6. Refrigerant article according to the preceding claim, characterized by a polysaccharide of marine origin.

7. Refrigerant article according to claim 6, characterized in that the polysaccharide is an agar, an alginate or a mixture thereof.

8. Refrigerant article according to claim 7, characterized by a composition containing 0.5% by weight of alginate and 0.5% by weight of Agar and 10% by weight of glycerol.

9. Refrigerant article according to any one of the preceding claims, characterized in that the envelope is a film of synthetic material, elastic in at least one direction.

10. Refrigerant article according to claim 9, characterized in that the elastic film is made of polyethylene.

11. Refrigerant article according to any one of the preceding claims, characterized by an external envelope in a material chosen from an elastic cotton fabric, a technical fabric mylar®, GoreTex® and a material having an external surface containing molecules received by spraying.

12. Refrigerant article according to claim 11, for an application in cryotherapy, characterized in that the pulverized molecules are natural essences of plants.

13. Refrigerant article according to claim 11 or 12, for application in cryotherapy, characterized in that the sprayed molecules are drug molecules.

14. Refrigerating article according to any one of the preceding claims, characterized by the presence of an external contact zone coated with a repositionable adhesive.

15. Refrigerant article according to any one of claims 1 to 14, characterized in that it comprises a headband part provided at each of its ends with pads made up of the flexible waterproof envelope containing the cryogenic composition.

16. Refrigerating article according to claim 15, characterized in that the pads are removable and replaceable, housings being provided in said article to receive them.

17. Refrigerating article according to any one of claims 1 to 14, characterized in that it has the shape of a compress provided on its contact face with a repositionable adhesive compatible with the skin and not alterable by the cold.

18. Article according to any one of claims 1 to 14, characterized in that it constitutes an internal covering for a rigid element, in particular a shell intended for an ankle or a knee, or a helmet.

19. Article according to claim 18, characterized in that the contact face of the covering is provided with repositionable adhesive.