FR2763111A1 - Multi layer insulating material - Google Patents

Abstract

The insulating material comprises one or more layers of a film material which is impermeable or only slightly permeable to air, covered with pieces of synthetic foam fixed in place by adhesive, thermal or high frequency welding, or by stitching. The film can have holes or incisions in which the foam pieces are fixed, or the foam can be used to fasten two layers of film together. The foam pieces are elongated in shape and lie in parallel rows; they can also be replaced by natural foam materials, plant stems, bark or wood, or natural or synthetic fibres. The film is of plastics, paper, metal foil or fabric, covered with synthetic foam pieces e.g. of plastics.

Description

 The present invention relates to a material intended to enter into the composition of multilayer thermal insulators.

 Thin layers of air, by limiting natural convection, have a very low equivalent thermal conductivity (conduction + convection) (down to 0.022 W.m1.K1 10.013 BTU.h-1. R-1. F-1 ). This property starts with multilayer thermal insulators which consist of one or more layers of air delimited by films of any material, impermeable or not very permeable to air. The thickness of said air layers ranges from a millimeter to a few centimeters.

 The thermal transmissivity of this type of insulation decreases further with the use of delimiting films made of low-emissivity materials in the infrared spectrum concerned (metal sheets), with the metallization of the surfaces of the films if they are made of a material more emissive, or with the inclusion of at least one metal sheet or with the metallization of at least one surface if the films making up the insulator are transparent to infrared thermal radiation.

 The technical problem is to maintain the air layers formed by preventing the boundary films from coming together, which would result in the reduction of the thickness of said air layers and the consequent increase in the thermal transmissivity of the insulation. .

 One of the existing solutions consists of inserting synthetic foam grids in the air layers.

 The disadvantage of this solution is the large quantity of scraps, the grids being produced by cutting whole sheets of synthetic foam.

 Another known solution is the stitching of a multitude of segments of wire in the carrier films, giving them a velvety appearance and a certain thickness.

 The disadvantage of this solution lies in the weakness of the thickness of the air layers which can thus be achieved and which decreases more with time and use, the segments of wire having a tendency to lie down.

 The solution provided by the present invention consists of a multitude of pieces of synthetic foam inserted into said layers of air, partially filling them, and fixed to one or two neighboring delimiting films. The pieces of foam, present in the air layers and distributed, if possible, regularly, oppose the bringing together of the delimiting films and the consequent reduction in the thickness of the air layers.

 Synthetic foams, being of a low thermal transmissivity and of a low density, are particularly indicated for the manufacture of wedging pieces.

However, other materials, objects or their fragments, with similar properties and characteristics which correspond to the requirements of the respective embodiments, may be used, in particular: synthetic straws or sheaths, natural straws, natural sponges or mosses, twigs, stems of plants, barks (including cork), wood (including balsa), rubber, pieces of: wadding, kapok, wool, glass wool, tangled synthetic fibers, corrugated cardboard.

In practice, the invention is in the form of a material intended to enter into the composition of multilayer thermal insulators, composed of a carrier film or of several superimposed carrier films, made of any material, impermeable (s) or not very breathable (such as plastic film, metallized plastic film, paper, metallized paper, metal sheet, fabric, metallized fabric, or their composites, gami (s) of a multitude pieces of synthetic foam (polyurethane, polyimide, polyethylene,
PP, PVC, aminoplast, phenolic, expanded polystyrene, for example) attached to the carrier film (s).

 The pieces of synthetic foam making up the layering can be attached to the carrier films by any relevant means, in particular by gluing, thermal or high frequency welding, sewing or introduction into incisions or holes made for this purpose in the carrier films.

 The carrier films can be perforated with a multitude of small holes or incisions, if necessary, in particular to allow the passage of water vapor or the evacuation of air during the compaction of the material, taking care however to do not make the carrier films too breathable, which would threaten the insulating qualities of the material.

 If several superimposed carrier films are used, an integral unit can be created by using the pieces of synthetic foam making up the filling as joining elements. Each piece (or part of the pieces) is then fixed to at least two carrier films at a time, and this so as to make, in the end, the superimposed carrier films inseparable. You can also use filiform pieces of foam for this and pass them each through several carrier films at the same time, so as to sew the carrier films together.

 By laying a layer or by superimposing several layers of the material according to the invention and by interposing or possibly wrapping them with simple films chosen from the same group of materials as the carrier films, a succession of films is obtained which are impermeable or not very permeable to l air and air layers partially filled with the pieces of synthetic foam. We then have a multilayer thermal insulator.

The present invention also makes it possible to design multilayer thermal insulators, the volume of which can be reduced for storage or transport purposes. Two particular embodiments are then offered:
1) the film (s) carrying (s) of pieces of synthetic foam of an elongated, threadlike shape will be gamira, which will traverse the film (s) carrying (s) in parallel lines (parallel in the context of the same carrier film, and, where appropriate, parallel in the context of all the superimposed carrier films), for each carrier film: (a) on one of its faces, (b) on its two faces or (c) alternately on both sides, squeezing through the incisions or holes made in the film.

 To apply the insulation, a layer of the material will be laid or several layers of the material will be superimposed, preferably by orienting the direction of the parallel lines of each immediately adjacent layer two by two in a crosswise fashion, and will be inserted or inserted therein. will eventually wrap simple films.

 To store or transport the insulation, we will arrange the layers of the material by orienting parallel (or almost) the directions of parallel lines of all the layers and we will roll or pick up the insulation while tightening it.

 The carrier films used must be flexible and tenacious enough to allow them to be folded or at least wound up.

 The volume reduction rate may approach the following value: (volume of the insulation deployed) / (volume of the pieces of foam used + volume of the carrier films used).

 2) the multilayer thermal insulation will be composed in any manner according to the invention, using (exclusively or in part) elastic synthetic foams, supporting compression without permanent deformation, and carrier films sufficiently flexible and tenacious to allow wrinkling, folding or at least winding.

 To store or transport the insulation, roll it up or pick it up while tightening it, or simply compress it.

 The rate of reduction of the volume may approach the following value: (volume of the insulation deployed) / [(volume of the pieces of foam used) / (rate of their compression inside the compacted insulation) + (volume of the carrier films used)).

As non-limiting examples:
A material intended to enter into the composition of the multilayer thermal insulators will be composed of a carrier film filled with filiform pieces of synthetic foam with a square section of 5 mm × 5 mm running through the carrier film in parallel lines spaced 3 cm apart. Each threadlike piece of foam threads through the carrier film through holes 5 mm in diameter placed each 6 cm, thus running alternately on both sides of the film. The holes are arranged in a regular mesh matrix of 6 cm x 3 cm and the threadlike pieces of foam of each immediately adjacent line two by two plunge and emerge in turn.

 Another material intended to enter into the composition of multilayer thermal insulators will be composed of a carrier film lined with pieces of synthetic foam in the form of a cube of 10 mm side, notched all around their circumference at their mid-height, the two halves remaining joined only by a sparse trunk 6 mm in diameter. The carrier film will be dotted with 6 mm diameter holes arranged in a regular 3.5 x 3.5 cm mesh matrix. Each cubic piece of foam will be compressed, introduced into a hole and released, one half on one side and the other on the other side of the carrier film, the latter going into the notch and encircling the spared trunk of the foam cube.

 In both cases, the pieces of foam remain firmly attached to the carrier film.

Use metallized polypropylene or polyethylene film 10 micrometers (0.0004 inch) thick and flexible open-cell polyurethane foam 20 kg.m9 (1.25 lb.ft3).

 In the first case, to compose a multilayer thermal insulator, layers of the material according to the invention will be superimposed by orienting the direction of the parallel lines of each immediately adjacent layer two by two at right angles.

 In the second case, layers of the material according to the invention will be superimposed quite simply.

 The two multilayer thermal insulators thus obtained will have the following characteristics: the average thickness of the air layers: 5 mm (0.2 inch), filling rate of the volume of the air layers with the pieces of foam: 16, 7%, calculated thermal transmissivity: 0.032 W.ml.K '(0.018 BTU.h-'. Ft1.0F1), density 5.4 kg.m3 (0.34 Ib.ft-3), compressibility: 12 times .

 The two multilayer thermal insulators described, each composed of a material according to the present invention, are light, with low thermal transmissivity, with high elastic compressibility, permeable to water vapor (the holes in the carrier films, even if partially obstructed by the pieces of foam (open cells) which pass through them, allow perspiration as well as the evacuation of air during compaction), and then prove to be specially adapted for use in sleeping bags, blankets , survival blankets, clothing and tents.

 The material according to the invention is particularly intended to enter into the composition of multilayer thermal insulators.

Claims (7)

 1) material intended to enter into the composition of multilayer thermal insulators characterized by the fact that it consists of a carrier film, or of several superimposed carrier films, made of any material, impermeable or slightly air permeable, gami (s) a multitude of pieces of synthetic foam attached to the carrier film (s).  2) material according to claim 1) characterized in that at least a part of the pieces of synthetic foam are fixed to (x) film (s) carrier (s) by gluing, thermal or high frequency welding, or by sewing.  3) material according to claim 1) or claim 2) characterized in that at least one carrier film is dotted with incisions or holes and that at least a part of the pieces of synthetic foam are introduced into the incisions or into the holes so as to remain fixed to the carrier film (s).  4) material according to any one of the preceding claims, composed of several superimposed carrier films, characterized in that at least part of the pieces of synthetic foam are attached to at least two carrier films at a time or that they pass through at at least two carrier films at a time, and this so as to form a whole integral unit preventing the carrier films from separating.  5) material according to any one of the preceding claims, with a reducible volume, characterized in that the pieces of foam are of an elongated shape, filiform, and that they line the film (s) carrying (s) by crossing it (them) in parallel or roughly parallel lines and that the film (s) carrier (s) is (are) flexible enough and tenacious (s) to allow its (their) folding or at least its (their) winding.  6) material according to any one of the preceding claims, with reducible volume, characterized in that the pieces of synthetic foam are made of an elastic foam supporting compression without permanent deformation, and that the film (s) carrier (s) ) is (are) flexible enough and tenacious (s) to allow its (their) wrinkling, its (their) folding or at least its (their) winding.  7) material according to any one of the preceding claims, characterized in that instead of part or all of the pieces of synthetic foam, other materials, objects or their fragments, with characteristics corresponding to the embodiments are used, namely: synthetic straws or sheaths, natural straws, natural sponges or mosses, twigs, plant stems, bark, wood, rubber, pieces of wadding, kapok, wool, glass wool, fibers tangled synthetics, corrugated cardboard.