Thermal insulating element

Abstract

Thermal insulation element comprising: • a thermal insulation panel; • a continuous peripheral vapor barrier layer. The continuous peripheral layer completely encases the insulation panel. This element allows the creation of removable insulation systems.

Description

[0001] The invention relates to a thermal insulating element. It also relates to a method for thermally insulating flat surfaces such as attic floors.

[0002] In the context of sustainable development, energy savings are becoming increasingly important. Energy consumption for heating buildings, particularly residential buildings, constitutes a significant share (for example, more than 20% in France) of total energy consumption. Improving the thermal insulation of buildings is therefore essential.

[0003] It is well known that thermally insulating materials must be protected from water vapor to prevent possible condensation within them. This problem is typically solved by placing a so-called "vapor barrier" or "vapor brake" membrane on the warm side of the insulation. In countries with a cold to temperate climate, this warm side is inside the building.

[0004] For example, in the case of temporary buildings or those under construction, or simply to allow certain inspections or modifications, the inventors believe that there should also be an interest in removable and recyclable insulating systems that can be moved and reused.

[0005] US6279284 describes a composite thermal insulation panel comprising a vapor barrier membrane. This panel is however intended to be permanently inserted, for example, into a metal structure ("stud"). Its dismantling is accompanied by a partial destruction of the panel since the latter includes the supporting structure of the wall.

[0006] CN104196138A describes a thermal insulation panel, composed of an inner panel and an outer panel, the outer panel comprising in particular a desiccant layer and a hydrophobic layer.

[0007] WO98 / 19024 describes a self-supporting insulating panel comprising a honeycomb insert, insulating material being distributed in the cells.

[0008] US2015 / 0354205 relates to vapor barrier membranes, comprising at least two layers, one of which has barrier properties that decrease with increasing humidity. These membranes improve the compromise of contradictory properties of vapor barrier membranes, which is on the one hand to protect insulation from water vapor penetration but also on the other hand to allow buildings to dry out.

[0009] The invention aims to provide an insulating element having good protection against water vapor while allowing its non-destructive disassembly.

[0010] Accordingly, the invention relates to a thermal insulating element comprising: a thermal insulation panel; a peripheral vapor barrier layer.

[0011] This element is characterized in that the peripheral vapor barrier layer is continuous and completely encases the insulating panel.

[0012] The thermal insulation panel has an approximately parallelepiped shape. Its surface area depends on the applications but typically varies between 0.1 and 4 m2. It is often greater than 0.25 m2, frequently greater than 0.5 m2. In general, it is less than 3 m2, often less than 2 m2. The thickness of the panel is commonly between 1 and 40 cm, with thicknesses between 5 and 20 cm being the most common.

[0013] The thermal insulation panel comprises at least 50% by volume of thermal insulation, preferably more than 75% and advantageously more than 80% or even more than 85% or 90%. Thermal insulation panels consisting essentially of thermal insulation are frequently used. Thermal insulation is understood to mean a material whose thermal conductivity is less than 0.1 W / m°K, preferably less than 0.05 W / m°K. Examples of such well-known materials are wood wool, hemp, glass or rock wool, expanded polystyrene, polyurethane foam.

[0014] According to the invention, the insulating element comprises a peripheral vapor barrier layer. This is intended to prevent water vapor from penetrating into the thermal insulation panel and condensing therein. This layer preferably has a resistance to water vapor diffusion (value "Sd") greater than 0.1 m, advantageously greater than 0.5 m, preferably greater than 1 m. This value expresses the thickness of a fictitious air layer having the same diffusion resistance. It is measured according to DIN 52615.

[0015] In the insulating element according to the invention, the peripheral vapor barrier layer is continuous and completely encases the insulating panel. This means that the outer surface of the insulating panel is entirely covered by the vapor barrier layer. In addition to the two main faces of the parallelepiped, its edges are therefore also covered by the vapor barrier layer. It should be noted that this fact makes it possible to use vapor barrier layers having Sd parameters higher than the maximum values ​​generally recommended (higher than 5 or even 10 m). Such maximum values ​​are in fact generally intended to allow the evacuation of condensed vapor that may have accidentally penetrated the thermal insulation. Complete encasement, especially if carried out in the factory, makes it possible to avoid this risk.

[0016] However, it is recommended that the Sd parameter does not exceed 10m.

[0017] It may be advantageous for the continuous vapor barrier layer to include a reinforcement, made of fibers providing this layer with the desired mechanical properties. These fibers can be of any length, well known to those skilled in the art. The use of continuous fibers made of ultra-high molecular weight polyethylene makes it possible to obtain elements with exceptional mechanical properties. Such insulating elements then become structural load-bearing elements, which can even be painted if necessary to meet aesthetic needs.

[0018] The continuous peripheral vapor barrier layer may consist of a pre-existing solid film that is applied to the insulating panel. This pre-existing film is preferably provided with a reinforcement. To obtain the coating from a flat film, the continuous layer must include joints that are made in a watertight manner, with the necessary overlaps. The sealing of the joints can be achieved by gluing, by using adhesive tapes, but preferably by welding the edges of the joints.

[0019] In this embodiment, it may be advantageous to assemble two different films on the main faces of the insulating panel, the two films having different values ​​of the Sd parameter. This variant allows, for example, one of the faces of the element to temporarily resist rain or permanently resist possible roof infiltrations (rain shield function).

[0020] In another embodiment of the invention, which is recommended, the continuous vapor barrier layer comprises a polymer and is monolithic. Monolithic is understood to mean a layer that does not comprise junctions. Such a layer can be obtained by applying a polymer, having the desired vapor barrier properties, in a pasty state to the panels, for example by spraying or by immersing the panels in a bath of the polymer in a pasty state. It is recommended that the continuous vapor barrier layer comprise at least 50% by volume, preferably at least 75%, of the polymer. The paste can be obtained by dissolving the polymer or by melting it when the polymer has a low melting point. Polymers of the polycaprolactone family, for example, have melting temperatures significantly lower than 100°C. After cooling or evaporation of the solvent, the monolithic continuous layer is obtained.In this recommended embodiment of the invention, if reinforcement is desired, it can be applied, in the form of continuous fibers, by winding it around the panel, before applying the polymer paste. This recommended embodiment of the invention, in which the continuous peripheral layer comprises a polymer and is monolithic, makes it possible to improve its vapor barrier properties, avoiding disturbances in these properties that occur at the junctions. The insulating elements are also juxtaposed with each other with more precision, improving the overall thermal insulation obtained.

[0021] In a variant of the invention, the insulating panel comprises at least 75% by volume of a moisture-sensitive insulating material. Moisture-sensitive thermal insulating materials are understood to mean materials such as, for example, wood wool, hemp, straw, but also glass or rock wool. These materials tend to absorb moisture and if this happens, they lose a significant part of their insulating properties or even deteriorate.

[0022] In this advantageous implementation method, the use of so-called natural insulating materials such as wood wool, hemp, and straw is recommended. Wood wool, for example, has low thermal conductivity but also good specific heat, which allows it to improve the thermal inertia of buildings. In addition, not only does its production emit little CO2, but it also allows it to be stored.

[0023] Natural insulating materials are advantageously biodegradable.

[0024] In the embodiments of the invention using a moisture-sensitive insulating material, and especially those known as natural, the insulating material generally has a density greater than 25 kg / m3, preferably greater than 30 kg / m3, more preferably 35 kg / m3. Insulating materials with a density greater than 40 kg / m3, or even greater than 45 kg / m3 or even greater than 50 kg / m3 are the most advantageous.

[0025] In an embodiment of the invention which is particularly advantageous when the insulating material is biodegradable and preferably selected from wood, hemp or straw, the continuous vapour barrier layer is also biodegradable. The biodegradability is assessed for example with the standards ISO 14851 or ISO 14855. It is recommended that the biodegradability of the continuous vapour barrier layer be of the same order of magnitude as that of the insulating material.

[0026] In a variant of this latter embodiment, the biodegradable continuous vapor barrier layer comprises starch or cellulose. Polymers such as cellulose acetate or other cellulose derivatives are considered to be cellulose. In this variant, the vapor barrier layer comprises more than 10% by weight of starch or cellulose, generally more than 25%, often more than 40%. The starch is preferably thermoplastic, i.e. it comprises a plasticizer such as glycerol. It is recommended that the continuous vapor barrier layer comprises a mixture of polymers such as polycaprolactone and starch or lactic acid and starch. The combination of thermoplastic starch and polyethylene, when thermoplastic starch is the continuous phase, is also advantageous, combining biodegradability and barrier properties.Ternary blends comprising thermoplastic starch, cellulose (e.g., in the form of fibers), and another polymer (e.g., polycaprolactone or polyethylene) are known for their combinations of interesting properties. When high biodegradability is desired, it is recommended that polymer blends have co-continuous phases.

[0027] In their practical applications, the elements according to the invention must be combined to cover sufficient surfaces. It is important that the various combined elements are in close contact to avoid losses of insulation by air convection between the elements. To this end, it is recommended that the elements be combined by compression, that is to say that a holding structure, such as an external frame, into which the elements are introduced, keeps them clamped. The density and thickness of the insulating panels used must enable them to withstand the compressive forces necessary to obtain sufficient airtightness for practical thermal insulation needs.

[0028] Sometimes the building naturally includes such a structure. This can be walls or the supporting structure of a roof. Generally, a simple structure is preferred. In general, it is recommended that the supporting structure have a surface area between 90 and 95% of the cumulative surface area of ​​the elements it supports, to achieve adequate compressive forces and the necessary close contact.

[0029] The invention therefore also relates to a thermal insulation system comprising a set of elements in accordance with the invention, assembled side by side, and a rigid compression-supporting structure, capable of maintaining the different elements of the set in close contact with each other.

[0030] As stated above, close contact means that the compressive forces of the elements between them, edge against edge, are sufficient to avoid convective air movements.

[0031] In cases where the panels cannot withstand these forces sufficiently, for example if their density is too low, it is certainly possible to supplement or cause the elements to remain in contact with each other by means of adhesive strips applied to the perimeters of the elements, the strip overlapping two adjacent elements. In this case, it is preferable to choose strips whose adhesive power is not too great to be able to be removed without damaging the vapor barrier layer of the element.

[0032] The invention also relates to a method for producing an element, the continuous vapor barrier layer of which comprises a polymer and is monolithic, according to which the polymer is applied in a pasty state to the insulating panel and then solidified. The pasty polymer can be sprayed or coated onto the insulating panel. The insulating panel can also be immersed in a bath of the polymer, which is in a pasty state. If the paste is obtained by heating the polymer, solidification is simply achieved by cooling. The softening temperature of the polymer must be compatible with the thermal resistance of the panels. In general, this temperature is less than 100°C. If the paste is obtained by dissolving the polymer in a solvent, solidification results from the evaporation of the latter.

[0033] In an advantageous embodiment of the method according to the invention, the polymer is made pasty and is applied to the panel by means of a thermal projection device, in which the polymer is injected in powder form into a stream of hot gas. Such devices, initially developed for the projection of metal powders, commonly introduce the powder into a stream of hot gas which has a high speed and is directed by means of a gun towards the target to be covered by the polymer. Said stream melts the particles of the powder and accelerates them to allow their impact with the target where they complete their fusion if necessary.These techniques, using hot gases at very high temperatures (obtained for example by combustion of propane) to obtain the fusion of metal particles, should preferably be adapted for the projection of polymer powders, these only briefly resisting the highest temperatures.

[0034] In a first variant of this advantageous embodiment, the thermal spraying device comprises means for controlling and reducing the temperature of the hot gas flow, in its part which contains polymer powder. Such means, which may comprise for example the introduction of cooling gas into the gas flow, have been described in particular in US4289807, US7216814 and US5503872.

[0035] In a second variant of this advantageous embodiment of the method according to the invention, which can be combined with the previous one, the polymer powder has a narrow particle size distribution width, σ less than 1.5, preferably less than 1.25. The width σ is defined as d 90 -d 10 / d 50 , determined by laser particle size analysis. A narrow particle size distribution makes it possible to improve the control of the temperature reached in the polymer particles after a given residence time in a hot gas stream.

[0036] The invention also relates to a thermal insulating element obtainable by the method according to the invention and its various embodiments and variants. The invention also relates to a method for thermally insulating a wall according to which a system according to the invention is arranged against the wall. The method according to the invention is particularly advantageous for insulating horizontal walls, such as attic floors, for example.

[0037] The elements, system and method according to the invention allow disassembly without damage to the insulating structure, which allows its complete and integral reuse.

[0038] The invention therefore finally relates to a method for successively insulating at least two walls according to which: a set of elements according to the invention are assembled to form a first system according to the invention and said system is arranged against a first wall, the system is removed from the wall and the elements disassembled, said elements are reassembled to form a second system the second system is arranged against a second wall.

[0039] This process can be continued several times. Example 1

[0040] A set of 24 wood fiber insulation panels, each 135 cm long, 57 cm wide and 14 cm thick, with a thermal conductivity of 0.036 W / °Km, are coated with a 0.2 mm thick polyethylene vapor barrier film. The joints are sealed by folding and hot air welding. During this operation, the 6 faces (including 4 edges) of the insulation panels are carefully covered with the vapor barrier film. This results in 24 insulating elements. A rectangular frame with internal dimensions of 385 cm X 435 cm is constructed inside a temporarily unused attic room using fir beams 5 cm thick and 15 cm high. This frame essentially covers the entire floor area of ​​the room.All 24 insulating elements are inserted into the frame (3X8), placing the elements side by side, so that the frame, whose internal surface is slightly less than the cumulative surface area of ​​the elements, compresses them against each other to avoid air convection between the panels.

[0041] When a technical operation has to be carried out in the room, certain elements are removed from the frame and then put back in place at the end of the technical operation. Example 2

[0042] Commercial granules of stabilized low density polyethylene (presence of antioxidants) are ground and then double sieved (>5 microns, <100 microns) to obtain a powder having a particle size distribution characterized by an average diameter d50 of 25 microns, a diameter d10 of 10 microns and a diameter d90 of 45 microns.

[0043] This powder is then introduced into a thermal polymer spraying system, as described above. This system allows the hot gas stream into which the polymer powder is introduced to be sprayed using a gun. The system allows the temperature of the part of the hot gas stream into which the powder is injected to be controlled at a value close to 350°C. The melting temperature of polyethylene being 105°C, the powder particles are melted. A thermal insulation panel made of wood wool, having a thickness of 14cm, a height of 135cm and a width of 57cm is furthermore preheated for 30 minutes in an oven set to a temperature of 95°C. The preheated panel is then coated with polyethylene by spraying said hot gas stream loaded with molten polyethylene particles. The surface temperature of the panel is controlled during spraying.The speed of the gun, at a distance of 50 cm from the panel, and the flow rate of projected particles are adjusted to produce a continuous peripheral vapor barrier layer thickness, on the 6 faces of the panel, made of polyethylene whose thickness is between 150 and 200 microns, while maintaining a surface temperature between 130 and 230°C during the impact of the particles on the panel. This results in a thermal insulating element in accordance with the invention, the continuous peripheral layer of which is monolithic.

Claims

1. Thermal insulating element comprising: • a thermal insulating panel, • a peripheral vapor barrier layer, characterized in that the peripheral vapor barrier layer is continuous and completely encases the insulating panel.

2. Element according to the preceding claim in which the continuous peripheral layer comprises a polymer and is monolithic.

3. Element according to the preceding claim in which the continuous peripheral vapor barrier layer is biodegradable and comprises starch or cellulose.

4. Element according to one of the preceding claims in which the insulating panel comprises at least 75% by volume of a moisture-sensitive insulating material, selected from wood wool, straw, hemp or wool.

5. Element according to one of the preceding claims in which the continuous peripheral vapor barrier layer has an Sd value greater than 0.1 m.

6. Element according to one of the preceding claims in which the continuous peripheral layer has different Sd values ​​on the two main faces of the insulating panel.

7. A method for producing an element according to claim 2 and claims 3 to 6 dependent thereon, wherein the polymer is applied in a pasty state to the insulating panel and then solidified.

8. Thermal insulation system comprising a set of elements according to claims 1 to 6, assembled side by side, and a rigid compression-supporting structure, capable of keeping the different elements of the set in close contact with each other.

9. Method for successively insulating at least two walls according to which: • a set of elements according to one of claims 1 to 6 are assembled to form a first system according to claim 8 and said system is arranged against a first wall, • the system is removed from the wall and the elements disassembled, • said elements are reassembled to form a second system • the second system is arranged against a second wall.

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