HIGH OPERATING TEMPERATURE DEVICE WITH AN INSULATING PRODUCT, SUITABLE INSULATING PRODUCT FOR SUCH A DEVICE AND METHOD FOR THE USE AND MANUFACTURE OF SUCH AN INSULATING PRODUCT

Description

[0001] The present invention relates to an installation (or apparatus or device) capable of operating at high temperature, in particular at temperatures up to 550°C and in particular between 50 and 350°C, such as a cooking oven, in particular an oven intended for domestic use, as well as a thermal insulation product suitable for the insulation of said installation or said oven, in particular suitable for the insulation of heating boxes of said ovens.

[0002] It is known to insulate parts or components of the oven, for example the cooking (or heating) enclosure (or chamber or box), or components such as one or more lighting sources of the oven, to protect in particular the components of the oven present around the enclosure or the external parts of the oven, from heat or overheating, as well as to prevent heat loss outside the enclosure, this insulation thus making it possible to improve the energy performance of the cooking oven during its use. The insulation used must be able to withstand the high temperatures to which they are exposed and to maintain their insulating performance at these temperatures without risk of degradation or emissions potentially harmful to health.

[0003] Furnaces are most often insulated with fibrous insulation, particularly based on synthetic fibers such as glass wool or rock wool, for example by using insulating layers based on fiberglass or mineral wool fabrics, the thermal performance of these insulators resulting in thermal conductivity values ​​λ (measured in particular according to the ISO 8302 standard) greater than 32-35 mW / mK, in particular of the order of 40 mW / mK, at room temperature, these values ​​increasing rapidly however with the temperature (for example being of the order of 60 mW / mK at 200°C, of ​​the order of 90 mW / mK at 300°C and of the order of 120 mW / mK at 400°C) and the energy consumption of conventional furnaces remaining relatively high.

[0004] Most other insulators existing in other applications are generally not suitable for insulating installations subject to high temperatures, these materials having better thermal performance at room temperature but being able to degrade or lose their good thermal performance at high temperature or over time. This is the case, for example, of cellular organic insulators of the expanded polymer or foam type, these materials degrade in particular at high temperature. Similarly, vacuum insulators, as well as aerogels, are not traditionally used in furnaces, these insulators by their nature and / or constitution and / or components presenting potential risks of degradation or loss of their thermal performance at high temperature.

[0005] The state of the art documents US 2014 / 057083 A1, US 6083619 A, US 5738801 A and WO 2014 / 126490 A1 are relevant to the present invention.

[0006] Even if conventional ovens are satisfactory, household appliances manufacturers, as well as users, continue to demand improvements in the energy consumption of ovens, with products that are functional and efficient from the first use, with a solid and safe construction, and these products maintain their performance over time.

[0007] The present invention therefore sought to develop a new installation (or apparatus or device), in particular domestic or household, operating at high temperature (in particular between 50 and 350°C), such as a cooking oven, and having good thermal performance over its entire range of operating temperatures (in particular between 50°C and 350°C), as well as improved energy consumption, this installation being furthermore able to be used efficiently and without risks from its first use.

[0008] This aim has been achieved by the device (or apparatus) according to the invention, operating between 50 and 350°C, this device comprising (or being provided with or coated with) at least one insulating product, said product being formed from at least one (thermally) insulating material based on aerogel(s), advantageously in the form of at least one layer, in particular at least one fibrous layer, based on aerogel(s) (or containing aerogels), said product comprising less than 0.55% by weight of hydrophobic agent(s), in particular less than 0.5%, advantageously less than 0.4%, or even less than 0.25%, in particular less than 0.1%, or even less than 0.05% by weight of hydrophobic agent(s), and preferably being free of hydrophobic agent(s).

[0009] As indicated later and preferably according to the invention, the level of organic components in the aforementioned insulating product is also less than 5.5% by weight of said product, in particular less than 3%, preferably less than 1.65%, the product being able in particular to be solely mineral.

[0010] The present invention also relates to the thermal insulation product (or insulator or insulating product) suitable for insulating the aforementioned high-temperature device (usable at), and its use in this application, this product being able to be obtained in various ways (in particular directly, or from existing products using a treatment (or transformation) process), as well as a possible process for obtaining said product from existing insulating products.

[0011] The insulating product according to the invention, in particular suitable (or intended) for the insulation of ovens (in particular for domestic use), is a product formed from at least one (thermally) insulating material formed (at least in part) from aerogel(s) (or based on aerogel(s) or containing aerogels or aerogel), said product or material being in the form of at least one fibrous layer (or based on fibers), containing aerogel(s), said material (or said layer) comprising in particular from 25 to 95% by weight of aerogel(s) (and generally from 5 to 75% by weight of fibers in the case of fibrous layer(s) formed from aerogel(s)), said product comprising less than 0.55% by weight of hydrophobizing (agent(s) or compound(s)) (grouping silicone(s) and hexamethyldisilazane), advantageously less than 0.5%, in particular less than 0.4%, in particular less than 0.25%, in particular less than 0.1%, or even less than 0.05% by weight of hydrophobizing agent(s), and preferably being free of hydrophobizing agent(s).

[0012] Aerogels are known as insulators in other applications, these aerogels being in the form of translucent granules or fine powder, and being efficient at room temperature in terms of thermal insulation, these aerogels can be used within mats (or sheets) formed of entangled fibers. These aerogels are difficult and expensive to obtain on an industrial scale, require delicate drying conditions and are sensitive to water which can degrade their thermal insulation properties, particularly over time. They thus traditionally include hydrophobic components resulting from the aerogel synthesis process and / or from additives added during the manufacture of these insulators.Surprisingly, however, the present invention has demonstrated that the removal of these hydrophobants or the absence of these hydrophobants in aerogel-based insulation materials for use in furnaces does not significantly affect the insulation properties of these insulation materials at the operating temperatures for this application, the insulation obtained being particularly satisfactory and improved compared to that obtained with traditional furnace insulation materials. Also surprisingly, the use of these products according to the invention makes it possible to improve the energy consumption performance of furnaces equipped with these products. Furthermore, these products or furnaces equipped with these products do not present any risk of emitting toxic products, and this from their first use.

[0013] The insulating product used according to the invention can be obtained directly or from existing products (comprising hydrophobants), these products having been in this case "dehydrophobic" (the hydrophobizing agents having been limited or preferentially removed or destroyed, for example by calcination as explained below).

[0014] Thus, a possible and satisfactory method for obtaining an insulating product according to the invention from existing products comprises at least one step of extracting the hydrophobic (agent) (or "dehydrophobation" step) from an insulating material based on aerogel(s) or from a product incorporating said material (in particular a commercial product), said material or said product comprising in particular from 25 to 95% by weight of aerogel(s).This extraction step is carried out in particular by subjecting said product or material to a heat treatment (or calcination step) at a temperature of at least 320°C, preferably at least 350°C, and advantageously less than 550°C, in particular less than 450°C, for at least 10 hours, and preferably for at least 12 hours, and advantageously for less than 20 hours, in particular so as to calcine or destroy, in whole or at least in part, the hydrophobic agents present, in particular so that the level of hydrophobic agent(s) within the product or insulating material based on aerogel(s) is / becomes less than 0.55% by weight (relative to the weight of said product or material), advantageously less than 0.5%, in particular less than 0.4%, in particular less than 0.25%, in particular less than 0.1%, or even less than 0.05% by weight, or even null.

[0015] This treatment process makes it possible to transform commercial aerogels in order to make them compatible with use as thermal insulators in the cooking ovens according to the invention, in particular in the heating boxes of said ovens, this transformation not causing harmful degradation as indicated previously.

[0016] The use of the product according to the invention, obtained directly or by processing already existing products (consisting of the removal or extraction of certain selected components used or having been used in the manufacture of aerogels), thus does not prevent good thermal insulation properties from being obtained and also makes it possible to improve the performance of the furnaces compared to those of furnaces using conventional mineral fibre insulation, while satisfying the requirements in terms of safety, health and the environment.

[0017] In particular, it is noted that the product or the oven equipped with the product remains below the emission threshold of volatile organic compounds (VOC) expected in this use, and this from its first use (the insulation according to the invention is therefore ready for use and can be inserted into the ovens without prior treatment), in particular advantageously has an emission of formaldehyde (or formalin) less than or equal to 10 mg / kg (i.e. less than or equal to 10 mg of formalin emitted / released per kg of said insulating product), in particular less than or equal to 8 mg / kg, preferably less than 5 mg / kg, or even less than 3 mg / kg, this emission being measured according to standard NF EN 120 and corresponding approximately to the maximum emission over 12 hours reached by the insulation during any heating exercise - cooking, pyrolysis - of the oven equipped with said insulating product,the heating temperature being between 50°C and 550°C (and in practice generally being between 50 and 240°C).,

[0018] The thermal insulation product according to the invention also has good fire resistance, good mechanical strength and good durability (or resistance to aging). In particular, it has a fire resistance of class A1 according to standard EN 13501-1, and a thermal conductivity of less than 50 mW / mK, preferably less than 40 mW / mK, or even less than 35 mW / mK at a temperature of 200°C (the thermal conductivity being measured according to standard ISO 8302), this conductivity being even lower at room temperature. Advantageously, the insulating product according to the invention also has a thermal conductivity of less than 50 mW / mK, in particular less than 40 mW / mK, at 300°C, as well as a thermal conductivity of less than or equal to 60 mW / mK, in particular less than 55 mW / mK, at 400°C.

[0019] The aerogel-based material forming the structure of the product according to the invention may incorporate aerogels in different forms (in particular in the form of beads or particles) or synthesized in different ways.

[0020] Aerogels are generally obtained from a gel, manufactured for example by hydrolysis in the presence of a solvent followed by gelation with catalysis from a precursor and then by evaporation or extraction of the liquid forming the gel (for example under supercritical or subcritical conditions) in order to replace said liquid with a gas (in particular air) without collapse of the porous structure. The aerogels thus formed are highly porous materials, with open pores, and whose pore size is nanometric.

[0021] The aerogels present in the product according to the invention are advantageously inorganic aerogels, in particular based on oxides, such as aerogels based on silica, aluminum and / or titanium. Preferably, the product according to the invention comprises at least one silica aerogel as aerogel(s), and preferably comprises essentially (for at least 50%, and preferably for 100%, by weight of the aerogels) or only silica aerogels.

[0022] Advantageously, whether the product or material formed from aerogel(s) according to the invention is formed from one or more insulating parts or layers based on aerogel(s), each part or layer preferably has a content of aerogel(s) of between 25 and 95%, and preferably of between 40 and 85% by weight of said part or layer or part, the content of aerogel(s) within the (final) insulating product according to the invention also being advantageously of between 25 and 95% (by weight of the product), preferably of between 40 and 85%.

[0023] According to the invention, the aerogel-based material(s) or layer(s) used or processed and forming the structure of the insulating product according to the invention are one or more fibrous layers (or layers formed from fibers), in particular of the mat(s) type (or mat(s) or sheet(s) formed from entangled fibers (in particular threads and / or filaments), forming a porous or “discontinuous” structure, containing aerogels. Each fibrous layer can be formed in a known manner, for example by depositing fibers, originating from a spinneret or another fiberizing device (in particular obtained by centrifugation and then drawn), on a mat, and possibly joining the fibers together by mechanical attachment, in particular by needling, or by chemical bonding using a binder applied to the fibers.Aerogels can be integrated into the fibers in various ways, either by mixing with preformed aerogels (manufactured independently of the fiber layers), or by impregnating the fiber layers with or in a solution for forming the aerogels in situ, for example by impregnating the layers with (a solution containing) the reagents for obtaining the aerogels, the extraction of the liquid and gelation being carried out (in particular under supercritical conditions) in order to obtain insulating layers containing aerogels. Examples of layers, or mats, of aerogels (reinforced by fibers) made by impregnation include aerogel mats marketed under the reference Spaceloft ® or Cryogel by the company Aspen Aerogel Inc.

[0024] Each fibrous layer may be formed from different types of fibers (inorganic and / or organic). Preferably, fibrous layers are chosen such that a majority (at least 50% by weight, in particular at least 75% or at least 80% by weight of the fibers), or even advantageously all, of the fibers of each layer, are inorganic / mineral fibers, these fibers being able in particular to be chosen from glass fibers (or glass wool), rock fibers (or rock wool), ceramic fibers, basalt fibers, etc., and preferably being glass fibers (for example E or C glass), or rock. Where appropriate, it is possible to have a small proportion of organic fibers (such as polyethylene, polypropylene, polyacrylonitrile, polyamide, aramid, polyester, polylactic acid, polyethylene terephthalate (PET) fibers, etc.).

[0025] The fibrous layers used where appropriate are advantageously porous and breathable, i.e. permeable to the diffusion of water vapour and air. They preferably have (each) a density of between 8 and 90 kg / m 3< , in particular between 20 and 90 kg / m 3< , in particular of the order of 30 to 80 kg / m 3< .

[0026] Commercially available aerogel-based materials generally comprise, in addition to the aerogels and where appropriate the aforementioned fibers, organic components resulting from their manufacture, such as hydrophobic agents as seen previously, the product according to the present invention further selects the aerogel-based material or layer(s) forming it in that they necessarily comprise less than 0.55% of hydrophobic agent(s) for use in ovens, as indicated according to the invention, such materials or layers being obtainable directly by eliminating or limiting the use of hydrophobic agents during the manufacture of these materials in order to obtain the required levels or by using the treatment method mentioned according to the invention from the commercially available aerogel-based materials or layers.

[0027] As already indicated, it is common in the usual processes for obtaining aerogel-based materials intended for thermal insulation (mainly for building walls or possibly for containers or pipes), to add a hydrophobic agent, mainly silicone or hexamethyldisilazane, in the initial composition making it possible to obtain the aerogels or during the synthesis of said aerogels or on the product resulting from said synthesis, the hydrophobation (or operation aimed at making the material hydrophobic) by the hydrophobic agent having in particular the aim of improving the resistance to aging of the product obtained and / or being considered as making it possible to contribute to obtaining low thermal conductivity.The level of hydrophobic agent(s), in particular silicone, and / or hexamethyldisilazane, in the aerogel-based materials obtained, in particular in the aerogel-based materials commercially available for thermal insulation (generally of building walls), can thus be up to 10% by weight (relative to the weight of the aerogel-based material(s).

[0028] By hydrophobic agent is meant an agent (or additive or compound), formed where appropriate of one or more components, making it possible to make the product incorporating it hydrophobic, this hydrophobic power being in particular evaluated by measuring the water absorption (water absorption value expressed in kg / m 2 < according to standard EN 1609 or in percentage according to standard ASTM C1511). According to the invention, the level of hydrophobic agent(s) present relative to all the compounds present (in dry / relative to the dry extract) in the product according to the invention is advantageously (made or chosen) less than 0.55%, advantageously less than 0.5%, in particular less than 0.4%, in particular less than 0.25%, in particular less than 0.1%, or even less than 0.05% by weight, or even zero, these agents being the aforementioned silicone and / or hexamethyldisilazane.Advantageously, the level of hydrophobic agent(s) in each part of the product according to the invention (including the material formed from aerogel(s)) is also less than 0.55%, advantageously less than 0.5%, in particular less than 0.4%, in particular less than 0.25%, in particular less than 0.1%, or even less than 0.05% by weight, or even zero. As indicated previously, the reduction of this level of hydrophobic agent(s) not only does not significantly impact the thermal insulation properties and / or the resistance to aging of the product obtained, under the conditions of its use in ovens, even after several firing cycles, but the oven thus equipped has better yields and the emission rate of formaldehyde, advantageously of VOCs, also remains less than or equal to 10 mg / kg (measured according to standard NF EN 120 - measurement method with hot tube at 350°C).As previously stated, these effects are particularly surprising because it is traditionally considered that the hydrophobizing agent is essential to ensure low conductivity of aerogels (the aerogel then being protected against the absorption of water at room temperature, absorption which would no longer make it insulating / conductive).

[0029] Each insulating material or layer used, in addition to having a limited hydrophobicity level, is also advantageously essentially (or even solely) mineral. The level of organic components present (evaluated in particular by measuring the mass of the material before and after calcination) is advantageously less than 5.5%, in particular less than 3%, preferably less than 1.65%, by weight of the product (and can also be reduced by the aforementioned method). The material or layer may, where appropriate, comprise a binder (in particular aqueous-based, this binder possibly comprising different organic or inorganic compounds (resin(s), additive(s), etc.)), at a level of less than 10% by weight of dry matter relative to the material or layer, this binder making it possible, where appropriate, in a fibrous layer, to bind the fibers together.Inorganic fillers and / or one or more preferably inorganic additives, at levels not exceeding 5% by weight, may optionally be present in the product according to the invention, in particular when one or more properties and / or functions are sought (presence, for example, of an opacifier).

[0030] The product according to the invention (or each insulating material or layer containing aerogels) generally comprises (or is formed from) 25 to 95% (in particular 40 to 85%) by weight of aerogel(s) (preferably inorganic), and where appropriate 5 to 75% (in particular 20 to 40%) by weight of fibers, preferably (for at least 50% by weight, and advantageously up to 100% by weight, of them) inorganic (in particular glass or rock fibers). This product is preferably of limited thickness, its thickness not exceeding 50 mm, and being advantageously less than 35 mm (the thickness of each layer where appropriate may be between 5 and 35 mm).

[0031] The product according to the invention is generally formed from a single type of aerogel-based material or a single insulating layer (with possible surfacing) but it can also comprise several insulating parts or layers, linked for example by gluing or superimposed, this product being able to be more or less dense (for example with a density of between 100 kg / m 3 and 250 kg / m 3), the fibers forming this product (in addition to the aerogels) being preferably (predominantly, at least 80% by weight of the fibers) E or C glass fibers (and possibly comprising a small proportion of organic fibers, in particular of the PET type). The product according to the invention can be enhanced, if necessary, with a surfacing, for example in glass veil, in particular to limit dust and / or be covered on its edge(s) with adhesive tape, for example in aluminum, for the same reason.

[0032] The insulating product according to the invention is generally in semi-rigid form and can be fixed on or around the walls or elements to be insulated by different means (gluing, stapling, fixing by screws, strapping, etc.).

[0033] It is particularly suitable for insulating all or part of the heating box of ovens (whether the door, the rear face or the side faces, also called belt), and / or for insulating and protecting certain elements of the oven (such as lamps). The insulation is positioned in particular around or on the walls or elements concerned.

[0034] The thermal performance of the insulation according to the invention results in thermal conductivity values ​​λ advantageously less than 50 mW / mK, preferably less than 40 mW / mK, or even less than 35 mW / mK at a temperature of 200°C (this conductivity being even much lower at room temperature), advantageously less than 50 mW / mK, or even less than 40 mW / mK, at 300°C, and particularly advantageously less than or equal to 60 mW / mK, or even less than 55 mW / mK, at 400°C. The thermal conductivity λ (in W / mK) represents the quantity of heat passing through the insulation (one meter thick, per m 2 < ). The thermal conductivity values ​​λ (compared to pressure, in particular atmospheric pressure (1 bar), and identical temperature, are measured using the guarded hot plate method (ISO 8302 standard).

[0035] The product according to the invention presents a good compromise in terms of thermal conductivity, VOC emission and fire resistance, and complies with health and safety requirements. The measurement of the level of formaldehyde emitted is carried out in particular in the present invention according to standard NF EN 120 (in particular by placing 10 g of sample in a tubular furnace at 350°C, a gaseous stream of reconstituted air passing through the sample for 1 hour, the formaldehyde released being trapped in 2 bubblers in series filled with 50 ml of water, and its cumulative quantity in the 2 bubblers being measured by the Lange method), by carrying out the measurement on a Hermann Moritz tubular furnace). The level of formaldehyde in the product according to the invention is less than 10 mg, or even less than or equal to 8 mg of formaldehyde per kg of product, preferably less than 5 mg / kg, or even less than 3 mg / kg.

[0036] The process for obtaining the product may, if necessary, include a finishing and packaging step, and / or a cutting step. In particular, it is possible to trim the edges of the insulating product or to cut the layer(s) or material(s) containing the aerogels to the required dimensions. A coating material may, if necessary, be applied to the surface in order to protect the product or reinforce it, for example a veil, tape, coating, etc.

[0037] The device or apparatus according to the invention is preferably an oven, or even part of an oven, in particular a cooking chamber, in particular for domestic use or possibly other (for example for industrial use), within which the temperatures can occasionally reach 450°C for example, or even 550°C or possibly more, this device comprising or being coated with at least one insulating product as previously defined. Advantageously, the device according to the invention only comprises as insulating product(s) one or more of the aforementioned insulating products according to the invention.

[0038] The present invention and its advantages will be better understood by reading the following examples, given solely for illustrative purposes and which cannot in any case be considered as limiting.

[0039] In the example according to the invention, a product was formed from an insulating blanket in the form of a mat impregnated with silica aerogels similar to the Pyrogel ®< XT-E type products marketed by the company Aspen Aerogel Inc., this blanket having a density of 0.20 g / cm 3< . The product formed according to the invention is formed solely of impregnated mat and has a thickness of 20 mm. It is then heat treated at 350°C for 12 hours. Monitoring of the volatile species at the end of the treatment showed that the final product has a final composition containing less than 0.2% of hydrophobic agent.

[0040] The thermal conductivity measurement was carried out according to the hot plate principle kept according to ISO 8302 standard at a temperature of 200°C and atmospheric pressure.

[0041] The measurement of the emitted formaldehyde rate was carried out on a Hermann Moritz tubular furnace according to standard NF EN 120.

[0042] The results obtained were as follows: thermal conductivity λ at 200°C: 30 mW / mK thermal conductivity λ at 300°C: 39 mW / mK formalin emission per kg of product: 10 mg / kg

[0043] The thermal conductivity of this product was compared to that obtained with a usual product for the insulation of ovens formed from mineral wool (reference example), this product being for example the product marketed under the reference TNF80 / 20 by the company Saint-Gobain Isover France, the thermal conductivity obtained for this usual product at 200°C being of the order of 55 to 70 mW / mK and that obtained for this usual product at 300°C being of the order of 75 mW / mK

[0044] An oven, reference De Dietrich CZ5702359 marketed by the company Brandt, was also equipped with an insulating inner belt by first using to form this belt the standard product according to the reference example, then replacing it with the product according to the invention according to the example, and the consumption of the ovens was measured according to the standard EN60350. The core heating measurements of the element to be heated were carried out on a brick marketed under the reference Hipor by the company Skamol, the brick having been previously dried, then immersed in a water bath placed at least 8 hours in the refrigerator until a brick temperature (measured in the brick by two thermocouples) of 5°C, the brick saturated with water and drained for approximately 1 min then being placed in the center of the oven.

[0045] The measurement of the energy consumption of the oven was carried out for two cooking positions, the ambient temperature of the oven environment being approximately 23°C, a traditional position according to the EN60350 standard with heating of the order of 140° (corresponds to a temperature in the center of the oven of 163°C (140°C heating compared to 23°C in ambient temperature)), 180° and 220°, and a forced ventilation position according to the EN60350 standard with heating of 135°, 155° and 175°, the test ending when the last of the two thermocouples present in the brick indicates a heating of 55° (absolute temperature of 60°C, the initial temperature of the brick being 5°C). The arithmetic mean of the energy consumption for each heating temperature was then calculated, in accordance with standard EN60350.

[0046] In the case of the oven having an insulating belt formed from the standard product according to the reference example, the consumption of the oven was 760 Wh, and in the case of the oven having an insulating belt formed from the product according to the invention according to example 1, the consumption of the oven was 630 Wh.

[0047] The results obtained show that the use of the products according to the invention for the insulation of domestic ovens or for other high-temperature uses makes it possible to obtain, for the ovens that these products equip, improved energy performance, the absence of hydrophobizing agent or the calcination of the hydrophobizing agent by heat treatment not resulting in any deterioration of the thermal performance of the insulation, said insulation having particularly satisfactory insulating performance even at high temperature, the emission of formaldehyde or VOCs being furthermore particularly limited despite the temperatures of use (10 mg / kg of formaldehyde being an admissible limit for use in cooking ovens).

[0048] In comparison on this last point, a product was formed from a mat impregnated with Pyrogel ®< XT-E type aerogels similar to that of the example according to the invention but which had not undergone heat treatment. Analysis of its organic matter content was typical of a composition containing more than 1% by weight of hydrophobizing agent. For this product, a thermal conductivity λ = 28 mW / mK at 200 °C and a formaldehyde emission per kg of product greater than 500 mg / kg were obtained, which was much too high for use in a domestic cooking oven. Similarly, with a less drastic heat treatment of the product (at 200°C for 12 hours), the analysis of the product was typical of a composition always containing more than 1% by weight of hydrophobizing agent and for this product a thermal conductivity λ = 30 mW / mK at 200°C and a formaldehyde emission per kg of product of 150 mg / kg was obtained, which was also too high for use in a domestic cooking oven.Conversely, a product resulting from a heat treatment at 500°C for 12 hours revealed a typical analysis of a composition containing less than 0.1% of hydrophobizing agent (example in accordance with the invention) and for this product a thermal conductivity λ = 34 mW / mK at 200°C and a particularly satisfactory formaldehyde emission per kg of product of 2 mg / kg were obtained.

[0049] The insulating product used according to the invention is particularly suitable for the insulation of walls or components of household ovens but can also be used with advantage for the thermal insulation of any other surface, in particular for applications (or for the insulation of products subjected to) high temperature.

Claims

1. An insulating product, suitable for the thermal insulation of an oven or a part of an oven, said product being formed from at least one insulating material based on aerogel(s) in the form of at least one fibrous layer, of the type of a mat or mats or pad or lap or laps formed from fibers, forming a porous or discontinuous structure, containing aerogels, characterized in that the said product comprises less than 0.55% by weight of hydrophobizing agent(s.

2. The insulating product as claimed in claim 1, characterized in that the thermal conductivity of said product is less than 50 mW / m.K at 200°C, advantageously less than 50 mW / m.K at 300°C, and particularly advantageously less than or equal to 60 mW / m.K at 400°C.

3. The insulating product as claimed in either of claims 1 and 2, characterized in that it comprises less than 0.5%, in particular less than 0.4%, or even less than 0.25%, in particular less than 0.1%, or even less than 0.05% by weight of hydrophobizing agent(s), and preferably being devoid of hydrophobizing agent(s).

4. The insulating product as claimed in one of claims 1 to 3, characterized in that the content of organic components in the insulating product is less than 5.5% by weight of said product, in particular less than 3%, preferably less than 1.65%, said product advantageously being solely mineral.

5. The insulating product as claimed in one of claims 1 to 4, characterized in that the said at least one fibrous layer comprises from 25% to 95% by weight of aerogel(s) and from 5% to 75% by weight of fibers.

6. The insulating product as claimed in one of claims 1 to 5, characterized in that its thickness is less than 50 mm.

7. The insulating product as claimed in one of claims 1 to 6, characterized in that the said at least one fibrous layer has a density which is comprised between 8 and 90 kg / m3.

8. The insulating product as claimed in one of claims 1 to 7, characterized in that that the said at least one fibrous layer is formed by fibers being chosen from glass fibers, glass wool, rock fibers, ceramic fibers and basalt fibers.

9. The insulating product as claimed in claim 8, characterized in that the fibers are glass fibers of E- or C-glass.

10. An oven or a part of an oven operating between 50 and 350°C, being equipped with an insulating product as claimed in one of claims 1 to 9.

11. A process for obtaining an insulating product as claimed in one of claims 1 to 9, said process comprising at least one step of extracting, in particular of calcinating, of the hydrophobizing agent(s), of an insulating material formed from aerogel(s) or of a product incorporating said material in such that the content of hydrophobizing agents in the insulating product or material formed from aerogel becomes less than 0.55% by weight, or even such that the product or material is devoid of hydrophobizing agents, said material or said product comprising in particular from 25% to 95% by weight of aerogel(s), said extraction step being carried out by subjecting said product or material to a heat treatment at a temperature of at least 320°C and less than 550°C, for at least 10 hours, and preferably for at least 12 h.