NOVEL CRYOGENIC COMPOSITION

Abstract

The present invention relates to a novel cryogenic composition intended to be used in thermal treatment devices, and also to its process of preparation. The invention also relates to a thermal treatment device and more particularly to a medical device used to cool a part of the human or animal body, in particular after trauma, inflammation or a surgical act. The invention has application in the therapeutic and/or medical field but also in other fields, such as, for example, for the cooling or the maintenance at low temperature of foodstuffs.

Claims

1. A cryogenic composition, comprising a hydrophobic compound in the liquid form in which granules of superabsorbent polymer charged with water and with humectant are immersed, said hydrophobic compound having a freezing point of less than 0 C.

2. The cryogenic composition as claimed in claim 1, which comprises: (a) from 0.2% to 3% and preferably from 0.2% to 2% by weight of a hydrophobic compound, the freezing point of which is less than 0 C., (b) from 1% to 6% and preferably from 1.5% to 3% by weight of superabsorbent polymer granules, (c) from 75% to 95% and preferably from 85% to 90% by weight of water, (d) from 6% to 10% and preferably from 7% to 9% by weight of a humectant, said percentages being expressed as percentages by weight with respect to the total weight of the composition, and the total weight of the composition representing 100%.

3. The cryogenic composition as claimed in claim 1, wherein the hydrophobic compound has a freezing point of less than 7 C., preferably of less than 10 C., more preferably of less than 15 C. and more preferably still of less than 20 C.

4. The cryogenic composition as claimed in claim 1, wherein said hydrophobic compound is chosen from neopentylene glycol diheptanoate, isopropyl sebacate, isodecyl neopentanoate, isostearyl isostearate and their mixtures.

5. The cryogenic composition as claimed in claim 1, wherein the superabsorbent polymer is chosen from crosslinked sodium or potassium polyacrylates, polyacrylamides, copolymers based on ethylene and maleic anhydride, vinyl alcohol copolymers, crosslinked polyethylene oxide, polymers based on starch, on gum and on cellulose derivatives, pectins, alginates, agar (or agarose), polyethyleneamines, polyvinylamines and their mixtures.

6. The cryogenic composition as claimed in claim 1, wherein said granules of superabsorbent polymer are provided in the form of spherical particles having a diameter of 1 to 6 mm when they are dehydrated, said spherical particles being able to absorb at least 40 times their weight.

7. The cryogenic composition as claimed in claim 6, wherein said spherical particles of superabsorbent polymer are sodium or potassium polyacrylate beads, advantageously potassium polyacrylate beads, having a diameter of 1 to 3 mm when they are dehydrated.

8. The cryogenic composition as claimed in claim 1, wherein the humectant is chosen from glycerol, sorbitol, polyethylene glycol, (di)propylene glycol, polypropylene glycol, 1,5-pentanediol, propylene glycol, butylene glycol, diethylene glycol, liquid paraffin and their mixtures.

9. The cryogenic composition as claimed in claim 8, wherein the humectant is dipropylene glycol.

10. A process for the preparation of a cryogenic composition as claimed in claim 1, comprising the following steps: (i) mixing the water and the humectant, under stirring, (ii) adding the granules of superabsorbent polymer to the mixture obtained at the end of step (i), under stirring, (iii) maturing the granules of superabsorbent polymer present within the mixture obtained at the end of step (ii), by allowing said mixture to stand at room temperature, preferably until the granules of superabsorbent polymer have reached a size of between two and four times their initial size, and (iv) incorporating the mixture obtained at the end of step (iii) in a container comprising the hydrophobic compound in the liquid form, under stirring.

11. The process as claimed in claim 10, wherein step (iii) of maturing the granules of superabsorbent polymer is carried out over a period of time ranging from 1 to 5 hours, and preferably over a period of time ranging from 2 to 4 hours.

12. A thermal treatment device, comprising a leaktight container, within which is contained a cryogenic composition as defined in claim 1.

13. The device as claimed in claim 12, wherein said container is a leaktight and flexible medical bag made of a material chosen from polyvinyl chloride (PVC), polychloroprene (neoprene), polytetrafluoroethylene (PTFE) or polyethylene (PE).

14. A medical device chosen from a face mask, a splint for the shoulder, elbow, ankle, knee, hip or wrist, and any support comprising a leaktight and flexible medical bag as defined in claim 13.

15. The use of a cryogenic composition as defined according to claim 1, for lowering or maintaining the temperature of foodstuffs, or for promoting their preservation, or for the transportation in cold environment of heat-sensitive articles.

Description

EXAMPLES

Example 1

[0040] A composition according to the invention is prepared by mixing 26.3 g of water with 2.24 g of dipropylene glycol (supplier: Interchimie), under manual stirring. 0.65 g of potassium polyacrylate beads having a diameter of 1.5 mm (Floragel hydrobeads, supplier: Axevi) are added to the water and dipropylene glycol mixture. The mixture is left standing at room temperature for 3 hours (step of hydration of the polymer beads), until the potassium polyacrylate beads have reached a mean diameter of 5.5 mm. 0.43 g of neopentylene glycol diheptanoate having a freezing point of 55 C. (DUB DPNG from Starinerie Dubois) is poured into a PVC bag of 5*7 cm with a thickness of 0.3 mm. The mixture, prepared beforehand, based on water, dipropylene glycol and potassium polyacrylate beads is also added to the PVC bag. The bag is subsequently sealed and placed in a freezer at 20 C. for 3 hours. During the freezing, a portion of the water present in the polymer beads changes phase and is converted into small ice crystals having the appearance of snow. Furthermore, the PVC bag remains flexible and conformable at the end of the freezing step.

[0041] The temperature of the sample is measured each minute for 70 minutes under a compression of 14 g.Math.cm.sup.2, using a Testo 175 T2 temperature recorder, with a probe of NTC type. The measurements are carried out every minute at the interface between the frozen bag and a bag of water at 20 C. with a thickness of 2 cm. The curve of temperature as a function of the time is represented in FIG. 1 (FIG. 1). The temperature of the bag always remains above 0 C. and stays below 5 C. for 61 minutes. The bag can thus be used for a cryotherapy treatment for 61 minutes.

[0042] The aging of the composition is also evaluated by measuring the number of freezing/thawing cycles. The aging becomes visible when the polymer beads begin to aggregate together, resulting in a decrease in the flexibility of the frozen bag. With the composition of the invention of example 1, the bag remains homogeneous and flexible up to the 25.sup.th freezing/thawing cycle.

Example 2

[0043] A composition according to the invention is prepared by mixing 1000 g of water with 10 g of butylene glycol, 10 g of pentylene glycol, 10 g of propylene glycol and 50 g of dipropylene glycol (supplier: Interchimie), under manual stirring. 25 g of potassium polyacrylate beads having a diameter of 3 mm (Floragel hydrobeads, supplier: Axevi) are added to the water, butylene glycol, pentylene glycol, propylene glycol and dipropylene glycol mixture. The mixture is left standing at room temperature for 3 hours (step of hydration of the polymer beads), until the potassium polyacrylate beads have reached a mean diameter of 8 mm. 5 g of isodecyl neopentanoate having a freezing point of 35 C. (DUB VCI 10 from Starinerie Dubois) is poured into a PVC bag of 5*7 cm with a thickness of 0.3 mm. The mixture, prepared beforehand, based on water, butylene glycol, pentylene glycol, propylene glycol, dipropylene glycol and potassium polyacrylate beads is also added to the PVC bag. The bag is subsequently sealed and placed in a freezer at 20 C. for 3 hours. During the freezing, a portion of the water present in the polymer beads changes phase and is converted into small ice crystals having the appearance of snow.

[0044] The temperature of the sample is measured each minute for 70 minutes under a compression of 14 g.Math.cm.sup.2, using a Testo 175 T2 temperature recorder, with a probe of NTC type. The measurements are carried out every minute at the interface between the frozen bag and a bag of water at 20 C. with a thickness of 2 cm. The curve of temperature as a function of time is represented in FIG. 2 (FIG. 2). The temperature of the bag always remains above 0 C. and stays below 5 C. for 58 minutes. The bag can thus be used for a cryotherapy treatment for 58 minutes.

[0045] The aging of the composition is also evaluated by measuring the number of freezing/thawing cycles. The aging becomes visible when the polymer beads begin to aggregate together, resulting in a decrease in the flexibility of the frozen bag. With the composition of the invention of example 2, the bag remains homogeneous and flexible up to the 25.sup.th freezing/thawing cycle.

Counterexample 1

[0046] A composition according to example 1 of the patent EP 1 011 558 is prepared by mixing 27.75 g of water with 1.80 g of propylene glycol, under manual stirring. 0.45 g of Terra-Sorb acrylamide copolymer beads having a diameter of between 1 and 6 mm (supplier: Plant Health Care) are added to the water and propylene glycol mixture. The mixture is left standing at room temperature for 3 hours (step of hydration of the polymer beads), until the potassium polyacrylate beads have reached a mean diameter of 8 to 9 mm. The composition thus prepared is placed in a PVC bag of 5*7 cm with a thickness of 0.3 mm. The bag is subsequently sealed and placed in a freezer at 20 C. for 3 hours.

[0047] As for example 1, the temperature of the sample is measured each minute for 70 minutes under a compression of 14 g.Math.cm.sup.2, using a Testo 175 T2 temperature recorder, with a probe of NTC type. The measurements are carried out every minute at the interface between the frozen bag and a bag of water at 20 C. with a thickness of 2 cm. The curve of temperature as a function of the time is also represented in FIGS. 1 and 2 (FIGS. 1 and 2), for comparison with the compositions of the invention of examples 1 and 2. The temperature of the bag remains below 0 C. for approximately 25 minutes and then stays between 0 C. and 5 C. for 24 minutes. The bag can thus be used for a cryotherapy treatment for 24 minutes.

[0048] As for examples 1 and 2, the aging of the composition is evaluated by measuring the number of freezing/thawing cycles. From the 1.sup.st cycle, it is observed that the bag is less homogeneous and less flexible than the bags of examples 1 and 2. With the composition of the patent EP 1 011 558, the bag remains homogeneous and flexible up to the 10.sup.th freezing/thawing cycle. From the 11.sup.th cycle, aggregation of the polymer beads is observed.

Counterexample 2

[0049] A composition analogous to that of example 1 above is prepared but without neopentylene glycol diheptanoate (absence of hydrophobic compound in the composition).

[0050] The frozen bag obtained is less flexible than that of example 1 containing the hydrophobic compound.

[0051] As for example 1, the aging of the composition is evaluated by measuring the number of freezing/thawing cycles. In the absence of hydrophobic compound, the composition exhibits premature aging from the 15.sup.th freezing/thawing cycle.

Counterexample 3

[0052] A composition according to the invention is prepared as described in example 1 by replacing the neopentylene glycol diheptanoate having a freezing point of 55 C. (DUB DPNG from Starinerie Dubois) with liquid petrolatum having a freezing point of 10 C. (Huile de Vaseline Codex 22 from Interchimie). The mixture thus prepared is added to the PVC bag. The bag is subsequently sealed and placed in a freezer at 20 C. for 3 hours. During freezing, the PVC bag becomes rigid: negative interactions between the liquid petrolatum and the PVC bag are observed. The bag is not sufficiently flexible to be able to be used as flexible medical bag.