FR2706740A1 - Composite material for making refrigerating (cooling) garments and garments produced - Google Patents

Abstract

The invention relates to a refrigerating composite material, for use in particular in making refrigerating garments, which works on the basis of a reversible endothermic absorption or reaction between an active solid and a suitable gas, characterised in that it comprises a first and a second jacket forming barriers to the said gas, and a porous layer, containing a mixture of active solid and either expanded graphite, or expanded and recompressed graphite, this layer being positioned between the said first and second jacket and being secured to at least one of the said jackets. Application to the production of refrigerating garments.

Description

 The invention relates to a composite material for the manufacture of cooling garments and clothing made using this material.

Bernard SPINNER, Didier HEINRY and Philippe
PRADES, belonging to the CNRS, collaborated in the development of the present invention.

 There is an unmet need to date for refrigerant garments to improve the comfort of people working in harsh weather conditions as a result of weather conditions or a nearby heat source.

 It is also known from EP-B-0 129 473 to carry out gas-solid type reactions in a reaction medium consisting of a mixture of expanded graphite with a density of 0.001 to 0.02 g / cm3. , and a solid reagent, the expanded graphite representing 1 to 60% of the solid reagent. Both exothermic and endothermic reactions can be carried out.

The use of expanded graphite makes it possible to shorten the duration of the total reaction and to increase the average power of the reaction.

 More recently, WO-A-91 15292 has described an active composite for the implementation of physicochemical processes using a gas and either a reactive solid or an adsorbent solid, which consists of a mixture of an active agent to to a gas and expanded graphite expanded with a density of 0.02 to 1.5. Preferably, the composite has a thermal anisotropy. The physicochemical processes that can be carried out can in particular be a reversible reaction of the solid-gas type, for example between a halide and ammonia or derivatives thereof.

 The invention aims to provide a refrigerant composite material useful for the manufacture of refrigerant clothing, applying the principles described in EP-B0 129 473 or WO-A-91 15292 whose teachings are incorporated herein by reference.

 More specifically, the invention relates to a refrigerant composite material, useful in particular for the manufacture of refrigerant garments, whose operation is based on a reversible endothermic reaction or absorption between an active solid and a suitable gas, characterized in that it comprises a first and second envelopes forming barriers to said gas, and a porous layer containing a mixture of active solid and either expanded graphite or expanded and recompressed graphite, disposed between said first and second envelopes and integral with at least one said envelopes.

 According to a particular embodiment, the operation of the refrigerant composite material is based on the absorption (or synthesis reaction) and the desorption (or decomposition reaction) of ammonia or one of its gaseous derivatives by a metal chloride alkaline earth (active solid), especially barium chloride or strontium. Other solid-gas couples that can be used are described in the aforementioned patent and patent application.

 For purposes of the invention, the terms "absorption" and "synthesis reaction" on the one hand, and the terms "desorption" and "decomposition reaction", on the other hand, are considered equivalent.

 In addition to the fact that the graphite component gives the active solid with which it is mixed a high gas permeability, because of its large specific surface, the graphite component also gives the porous impregnated layer a very good thermal conductivity, which allows the frigories generated in the composite material to quickly reach the inner casing of the garment and to effectively ensure the desired cooling effect.

 The porous layer containing said mixture may be an open-pore flexible synthetic foam layer, for example a polyester, polyurethane or silicone foam, impregnated with said active solid-graphite mixture.

The first and second envelopes, gas-tight used, may be of the same or different natures. Such gas barrier shells are well known in the art. Non-limiting examples are a polyvinyl chloride (PVC) or polyurethane-based film, or a multilayer film, for example a film comprising a polyethylene layer, a biaxially oriented polyamide layer and a polyethylene layer bonded together. Envelopes, besides being gas-tight, must be sufficiently heat-resistant to withstand the temperatures at which the final garment may be exposed, and may exceed 100 ° C. They must also be made mechanically strong enough to withstand the pressure internal gas which is generated during the desorption and especially during the subsequent regeneration of the composite material and which can reach a few bars.For this purpose the barrier material, can be doubled externally of a reinforcing material such as a fiber fabric of carbon or aramid fibers (such as Kevlar (R) fibers commercially available from EI
NEMOURS BRIDGE).

 In practice, a suitable gas (for example ammonia) is initially absorbed by the active solid (for example barium chloride) contained in the porous layer of the composite material. When thereafter the desorption of said gas is caused, this desorption, which is endothermic, produces cold. The desorption can be caused by putting the porous layer in communication with another active solid, placed under thermodynamic conditions such that it has a synthesis reactivity with respect to said gas (NH3 for example) greater than that of the solid active ingredient incorporated in the layer of the composite of the invention, placed him under decomposition conditions.

 The following nonlimiting example is given for the purpose of illustrating the invention.

EXAMPLE
A composite material according to the invention was prepared as follows
A 5 mm thick layer of a polyester foam with a density of 30 kg / m 3, having a weight per unit area of 150 g / m 2 and an open porosity of approximately 12 pores per cm 2, is impregnated a saturated aqueous solution of barium chloride containing a water-soluble adhesive and, in suspension, fine particles of expanded natural graphite with a specific mass of 3 g / liter, and then dried.

 The resulting dry impregnated foam layer contained, per m 2 of foam, 350 g of graphite and 900 g of Bacul 2.

 This impregnated foam layer was melt-bonded between two sealed films each composed of a 20 μm thick biaxially oriented polyamide layer sandwiched between two layers of polyethylene 50 μm thick and mutually laminated.

 The composite material thus obtained had a thermal conductivity of 0.7 Wm-1 R1 + 0.2. A rectangular piece of this composite material, with a surface area of 0.5 m2, was heat sealed on all four sides by providing two gas inlet and outlet ends, respectively, on opposite sides of the rectangle. The inlet nozzle was connected to a source of ammonia gas and ammonia, at a pressure of 2 bar, was passed through the foam layer impregnated with the composite material so that the ammonia reacted with the ammonia gas. barium chloride (active solid) forming BaCl2, 8NH3.

 The inlet nozzle was then sealed and the outlet nozzle connected to a reservoir containing a compound having a higher ammonia synthesis reactivity than BaCl 2, for example MnCl 2 manganese chloride.

A significant cold production was then observed (50 W at an outside temperature of 35 ° C.) This cold production results from the endothermic reaction of ammonia from BaCl2, 8 NH3 over MnCl2, 2NH3 according to the two half-lives. equations

<tb> 1/4 [Mn (NH3 <SEP>) 21Cl2 <SEP> + <SEP> NH3 <SEP> (gas) <-> 1 / 4Mn (NH3 <SEP>) 6] C12
<tb><SEP> 1/8 [Ba (NH3 <SEP>) 81Cl2 <SEP><-<SEP>-> l / 8BaCl2 <SEP> + NH3 (gas)
<Tb>
The cooling composite material can be regenerated by heating the MnCl 2, 6 NH 3 reservoir, for example, to a temperature of about 140 ° C so as to desorb the ammonia and return it to the composite material to reform BaCl 2, 8 NH 3.

 The composite material of the invention can operate in any position and without evaporator unlike conventional refrigerators. It also does not require a source of energy, which gives it remarkable autonomy properties, which makes it very suitable for the production of refrigerant clothing. In addition to this application, the composite material of the invention could be used for the manufacture of portable refrigerant containers, for example for picnics.

 It goes without saying that the embodiment described is only one example and that it could be modified, in particular by substitution of technical equivalents, without departing from the scope of the invention.

Claims (8)

 1. Composite refrigerant material, useful in particular for the manufacture of refrigerant garments, whose operation is based on a reaction or reversible endothermic absorption between an active solid and a suitable gas, characterized in that it comprises a first and a second envelopes forming gas barriers, and a porous layer, containing a mixture of active solid and either expanded graphite or expanded and recompressed graphite, disposed between said first and second envelopes and integral with at least one of said envelopes.  2. Material according to claim 1, characterized in that the porous flexible layer is a layer of open pore synthetic foam impregnated with said active solid-graphite mixture.  3. Material according to claim 1 or 2, characterized in that the reversible endothermic reaction or absorption involves an alkaline earth metal chloride and ammonia or a gaseous derivative thereof.  4. Material according to claim 3, characterized in that the reaction or absorption involves barium chloride and ammonia, or strontium chloride and ammonia.  5. Material according to any one of claims 1 to 4, characterized in that it is connected to a reservoir containing another active solid, placed under thermodynamic conditions such that it has a synthetic reactivity vis-à- screw of said gas (NH3 for example) greater than that of the active solid incorporated in the layer of the composite of the invention.  6. Material according to claim 5, characterized in that said compound having a synthesis reactivity with the upper ammonia is manganese chloride.  7. Material according to claim 1, characterized in that at least one of the envelopes is lined externally with a reinforcing material.  8. Refrigerant clothing, characterized in that it is made from a composite material according to any one of claims 1 to 7.