Composition for an insulating coating

Abstract

The subject of the invention is a composition comprising flakes of mineral or plant wool, a mineral binder in powder form and a water-soluble polymer comprising hydroxyl groups, wherein the content of mineral or plant wool is between 50 and 90% by weight and the content of mineral binder is between 10 and 50% by weight relative to the total weight of mineral or plant wool and of mineral binder. The invention also relates to a method for obtaining an insulating coating and to a building element comprising a support coated with an insulating coating on one of its surfaces.

Description

Composition for insulating coating

[0001] The invention relates to the field of construction. It concerns more particularly the production of coatings having good thermal insulation properties.

[0002] It is known to thermally insulate buildings from the outside, by placing panels of insulating material, for example mineral wool or polystyrene, on the exterior walls of buildings. This technique allows, compared to interior insulation, a gain in space for the occupants, as well as better thermal insulation due to the elimination of thermal bridges. Different construction systems are used for this purpose. These include ventilated facade systems, in which facing panels are held by frames at a certain distance from the insulation, so as to create an air gap, or external insulation systems (ITE or ETICS), in which reinforcing and finishing coatings are directly placed in contact with the insulation. In these different techniques, the insulating panels are fixed to the wall to be insulated either using mechanical fasteners or adhesives.

[0003] However, these techniques are complex and require significant installation time, particularly for fixing the insulation and cladding panels. Cutting the panels on site also generates large quantities of waste, and poor panel joints can lead to reduced thermal insulation performance.

[0004] The aim of the invention is to propose a construction technique and compositions adapted to this technique, which make it possible to thermally insulate facades more effectively, with simpler and faster implementation.

[0005] To this end, the subject of the invention is a composition comprising flakes of mineral or vegetable wool, a powdered mineral binder and a water-soluble polymer comprising hydroxyl groups, in which the weight content of mineral or vegetable wool is between 50 and 90% and the weight content of mineral binder is between 10 and 50%, relative to the total weight of mineral or vegetable wool and mineral binder. The composition is generally dry, i.e. essentially consisting of a powdered mixture.

[0006] The invention also relates to a method for obtaining an insulating coating on or against a support, comprising mixing such a composition with water and depositing the mixture obtained on or against said support.

[0007] The invention finally relates to a building element comprising a support coated on one of its surfaces with an insulating coating comprising mineral or vegetable wool flakes bound together by a hardened mineral binder, and a water-soluble polymer comprising hydroxyl groups. The insulating coating is preferably obtained or capable of being obtained by the method according to the invention.

[0008] The use of a composition according to the invention for depositing, in particular by spraying, an insulating coating, makes it possible to overcome the aforementioned drawbacks. Surprisingly, the invention also makes it possible to ensure good adhesion of the insulating coating to the walls (in particular, but not only, to concrete walls), good cohesion of the coating even for the significant thicknesses generally required by the targeted insulating performances, good resistance to the environment and to aging, as well as good mechanical properties, in particular in compression and in tension, for a reduced carbon impact and good thermal insulation properties. The addition of a polymer comprising hydroxyl groups makes it possible to improve adhesion in the fresh state, thus making it possible to increase the thickness of the coating. It also improves the mechanical strength, in particular the tensile strength.Without wishing to be bound by any scientific theory, it would seem that these polymers, due to their rapid dissolution upon contact with water, are capable of very quickly forming an organic binder for the flakes, thus improving the cohesion of the coating.

[0009] After mixing the composition with water and hardening the mineral binder, the resulting coating comprises flakes of mineral or vegetable wool bound together by a hardened mineral binder. The powdered mineral binder present in the composition becomes pasty after mixing with water, before hardening. The term "binder" therefore covers both the powdered binder present in the composition and the final hardened binder in the final coating. The following details apply to both the composition and the final coating.

[0010] The mineral wool is preferably selected from glass wool, slag wool and rock wool. The mineral wool fibers preferably have a chemical composition comprising 30 to 75% by weight of SiO2, 5 to 40% CaO+MgO, 0-20% Na2O+K2O, 0-30% Al2O3 and 0-15% Fe2O3.

[0011] The use of glass wool generally allows better thermal insulation performance to be achieved, in particular thanks to a lower density.

[0012] Glass wool is generally formed by electrical or flame melting of a mixture of powdered raw materials and cullet (recycled glass), followed by fiberization, particularly by internal centrifugation using a fiberizing plate. The fibers of the glass wool preferably have a chemical composition comprising 50-75% by weight of SiO2, 12 to 20% Na2O+K2O, 5 to 20% CaO+MgO, 0-8%, especially 0-3% Al2O3 and 2 to 10% B2O3. Alternatively, the chemical composition may comprise 39-44% by weight of SiO2, 9-15% Na2O+K2O, 6-20% CaO, 1-5% MgO and 16-27% Al2O3.

[0013] Rock and slag wools are generally formed by cupola melting of raw materials in the form of blocks or briquettes, or by electric melting or submerged burners of powdered materials, followed by fiberization by external centrifugation using a plurality of rotors. Rock wool fibers preferably have a chemical composition comprising 30-50% SiO2, 10-27% Al2O3, 15-40% CaO+MgO, 0-5% Na2O+K2O and 3-15% Fe2O3. Slag wool fibers preferably have a chemical composition comprising 30-45% SiO2, 5-18% Al2O3, 30-60% CaO+MgO and 0-3% Na2O+K2O.

[0014] Mineral wool is generally made up of interwoven vitreous fibers. The mineral wool used generally does not contain an organic binder. However, it may contain organic binders when the flakes are recycled from construction or factory waste, for example, obtained by crushing mineral wool panels. The flakes may be blown wool flakes, which do not normally contain an organic binder, but may nevertheless contain organic additives, such as silicone or antistatic agents. These additives are sprayed onto the mineral wool during fiberization.

[0015] Vegetable wool comprises vegetable fibers preferably selected from the group consisting of lignocellulosic fibers and cotton fibers. The lignocellulosic fibers are preferably selected from wood fibers, hemp fibers, flax fibers, sisal fibers, cotton fibers, jute fibers, coconut fibers, raffia fibers, abaca fibers, cereal straw, rice straw and mixtures thereof.

[0016] Flakes are pieces formed from agglomerates (or clusters) of entangled fibers having a certain size or dimension. It is essential that the composition and coating include the fibers in the form of flakes and not in the form of dispersed individual fibers or fibers organized in the form of sheets, grids, fabrics or nonwovens, in order to achieve good thermal insulation properties. The coating is therefore distinguished from a fiber-reinforced coating or mortar, which does not have insulating properties.

[0017] The mineral or vegetable wool flakes in the composition and / or the coating preferably have a size of between 2 and 100 mm, in particular between 5 and 80 mm, or even between 6 and 70 mm. Preferably, at least 80% by mass of the mineral or vegetable wool flakes have a size of between 5 and 30 mm, in particular between 6 and 13 mm. Flakes that are too small lead to denser coatings, and therefore less thermally insulating. Obtaining the flakes and adjusting their size can in particular be carried out using a carding machine. The flakes can be larger in the composition, in the case where the projection machine is capable of reducing their size before projection. The size of the flakes can in particular be determined by sieving.This can be done, for example, by using a vibrating sieve machine with a stack of sieves and a maximum oscillation amplitude of 3 mm set between 1.5 and 2.5 mm, preferably between 1.8 and 2.2 mm and better still at 2 mm, for 5 minutes.

[0018] The powdered mineral binder is preferably a hydraulic binder.

[0019] The hydraulic binder is preferably selected from the group consisting of Portland cements, belitic cements, aluminous cements, sulfoaluminous cements, pozzolanic mixture cements, slags, fly ash, metakaolins, hydraulic lime, calcium sulfate sources and mixtures of two or more of these hydraulic binders. The calcium sulfate source is in particular selected from gypsum, anhydrite, hemihydrate and their mixtures. The hydraulic binder may be a latent hydraulic binder.

[0020] The binder may in particular consist of Portland cement, notably type CEM I or CEM II.

[0021] According to another embodiment, the binder comprises (in particular consists of) a mixture of Portland cement and a source of calcium sulfate, and optionally aluminous cement. The presence of a source of calcium sulfate makes it possible in particular to improve the fire resistance properties and to accelerate the setting of the binder. Its carbon impact is also reduced compared to Portland cement. The proportion of calcium sulfate source in this binder is preferably between 2 and 20% by weight, in particular between 5 and 15% by weight.

[0022] According to another embodiment, the binder comprises (in particular consists of) a mixture of sulfoaluminous cement and a source of calcium sulfate. The binder then preferably comprises a setting accelerator, for example a lithium salt. The proportion of calcium sulfate source in this binder is preferably between 2 and 20% by weight, in particular between 5 and 15% by weight.

[0023] According to yet another embodiment, the binder comprises (or consists of) a mixture of Portland cement, aluminous cement and a source of calcium sulfate. The binder may also comprise a setting accelerator, for example a lithium salt. Such a binder allows the hardening to be completed more quickly. In this embodiment, the weight proportions of the constituents in the binder are preferably as follows: 65 to 90% Portland cement, 5 to 20% aluminous cement and 2 to 15% of a source of calcium sulfate.

[0024] Generally speaking, the presence of Portland cement allows good mechanical performance to be achieved, particularly in terms of compressive strength, and also allows high pH values ​​to be achieved, which have been shown to promote the effectiveness of possible water-repellent agents. The addition of a source of lime to the aforementioned binders has also been shown to be beneficial in this regard.

[0025] The binder can also consist of a source of calcium sulfate, which provides good fire resistance properties, but at the expense of mechanical and thermal insulation properties.

[0026] Alternatively, the mineral binder can be a clay binder.

[0027] Preferably, the composition further comprises a water-repellent agent. The water-repellent agent provides good resistance to aging of the coating, particularly when the latter is installed on the exterior of buildings. It appears that its presence helps limit undesirable interactions between the binder, which is very alkaline, and the mineral wool fibers, which are sensitive to alkaline environments.

[0028] Particularly preferably, the water-repellent agent comprises (or consists of) an organosilicon compound, in particular comprising silane and / or siloxane groups, monomeric, dimeric, oligomeric or polymeric.

[0029] Such water-repellent agents have proven to be much more effective than other known water-repellent agents such as sodium, potassium or calcium salts of fatty acids, for example calcium stearate or sodium oleate.

[0030] The organosilicon compound is preferably chosen from:- organosilanes, such as tetraorganosilanes, of formula SiR4, for example tetraalkylsilanes,- organosiloxanes, such as tetraorganosiloxanes, of formula Si(OR)4, for example tetraalkoxylsilanes such as tetramethoxysilane and tetraethoxysilane,- organoorganoxysilanes, in particular of formula SiR n (GOLD') 4-n where n=1 to 3, such as alkylalkoxysilanes, in particular isooctyltriethoxysilane, n-octyltriethoxysilane or hexadecyltriethoxysilane,- organosilanols, in particular of formula SiR n (OH) 4-n - oligosilanes and polysilanes, - oligosiloxanes and polysiloxanes (also called silicone resins, for example methylsilicone, ethylsilicone, phenylsilicone or H-silicone resins), in particular comprising at least one unit of general formula R a H b If(OR') c (OH) d O (4-a-b-c-d) / 2, with a=0 to 3, b=0 to 1, c=0 to 3, d=0 to 3 and a+b+c+d ≤ 3.5, in which, in the above-mentioned formulae, the radicals R are identical or different and represent branched or unbranched alkyl radicals having from 1 to 22 carbon atoms, cycloalkyl radicals having from 3 to 10 carbon atoms, alkylene radicals having from 2 to 4 carbon atoms, or aryl, aralkyl, alkylaryl radicals having from 6 to 18 carbon atoms, and the radicals R′ are identical or different alkyl and alkoxyalkylene radicals each having from 1 to 4 carbon atoms, preferably methyl and ethyl, the radicals R and R′ can also be substituted by halogens such as Cl, by ether, thioether, ester, amide groups, nitrile, hydroxyl, amine, carboxyl, sulfonic acid, carboxylic anhydride and carbonyl.

[0031] The water-repellent agent is preferably in powder form. It may, for example, comprise the organosilicon compound and an inorganic or organic solid support. Possible inorganic supports are, for example, based on silica (such as precipitated silica or fumed silica), carbonates or talc. They are preferably porous, with a BET surface area preferably of at least 50 m² / g, or even at least 100 m² / g.

[0032] The water-repellent agent may also be a redispersible powder. It may then comprise polymers, in addition to the organosilicon compound. These polymers are, for example, based on one or more monomers chosen from the group comprising vinyl esters (in particular vinyl esters of unbranched or branched alkylcarboxylic acids having from 1 to 15 carbon atoms), methacrylates and acrylates (in particular (meth)acrylates of alcohols having from 1 to 10 carbon atoms), methacrylic acid, acrylic acid, vinyl aromatics, olefins, dienes and vinyl halides. The powder may also contain water-soluble protective colloids, fatty acids and / or anti-blocking agents.

[0033] Water-repellent agents that are particularly effective in the context of the invention are marketed in particular by Wacker Chemie AG under the references Silres® Powder A and D.

[0034] The water-repellent agent can be added in powder form to the composition, and / or be present as a coating on the surface of the mineral wool fibers.

[0035] The polymer comprising hydroxyl groups is water-soluble, i.e. soluble in water, especially in cold water. By water-soluble polymer, we mean that the polymer is capable of forming a solution in water.

[0036] Preferably, in the polymer comprising hydroxyl groups, at least 20% of the units have a hydroxyl group. This proportion is even advantageously at least 30%, in particular at least 40%, and even at least 50% or 60%.

[0037] The polymer comprising hydroxyl groups is preferably a vinyl polymer. A particularly preferred polymer is poly(vinyl alcohol), also called polyvinyl alcohol, which has high solubility in water. The polymer comprising hydroxyl groups is preferably not a cellulose derivative.

[0038] The polymer comprising hydroxyl groups is preferably in powder form. In order to ensure very rapid dissolution in water, the powder preferably has a volume particle size distribution such that the D90 is at most 200 µm, in particular at most 180 µm. The determination of the D90 is carried out in particular by laser particle size analysis.

[0039] The mass-average molar mass of the polymer comprising hydroxyl groups, in particular poly(vinyl alcohol), is preferably between 20,000 and 300,000 g / mol, in particular between 30,000 and 250,000 g / mol, in particular between 150,000 and 200,000 g / mol. Particularly suitable poly(vinyl alcohol) powders are, for example, marketed under the references Selvol® E205S and E575S by the company Sekisui.

[0040] The composition according to the invention may comprise other constituents.

[0041] It may in particular include lightening fillers, in particular chosen from perlite, vermiculite, expanded glass beads, expanded polystyrene beads, cenospheres, expanded silicates, aerogels and their mixtures.

[0042] The composition advantageously comprises redispersible polymer powders. The polymer is preferably based on one or more monomers chosen from vinyl esters (in particular vinyl esters of C1-C15 carboxylic acids such as vinyl acetate), (meth)acrylates (in particular of C1-C10 alcohols), vinyl aromatics, alkenes (for example ethylene), dienes and vinyl halides. These polymers make it possible to improve the mechanical strength of the coating, without affecting its thermal insulation properties.

[0043] The composition advantageously includes thickening agents, which also make it possible to improve the mechanical resistance of the coating without affecting its thermal insulation properties, and to obtain better cohesion. The thickening agent is preferably a cellulose ether.

[0044] The composition may also comprise surfactants, in particular to facilitate the wetting of the fibers by water during the implementation of the coating deposition process. An advantageous surfactant is in particular sodium dodecyl sulfate.

[0045] The composition may further include mineral or vegetable oils, in order to reduce dust emissions, particularly when the binder contains a source of calcium sulfate such as gypsum.

[0046] The weight content of mineral or vegetable wool is between 50 and 90%, particularly between 55 and 85%, relative to the total weight of mineral or vegetable wool and mineral binder, or even to the total weight of the composition or coating. Given the low density of mineral or vegetable wool flakes compared to the binder, mineral wool is therefore very clearly the majority in volume, making it possible to achieve good thermal insulation properties.

[0047] The weight content of mineral binder is between 10 and 50%, particularly between 15 and 45%, relative to the total weight of mineral or vegetable wool and mineral binder.

[0048] In the case of slag wool, the mass proportion of wool to binder preferably varies from 70:30 to 90:10. In the case of glass wool, the mass proportion of wool to binder preferably varies from 50:50 to 70:30.

[0049] The weight content of polymer comprising hydroxyl groups is preferably between 1 and 10%, in particular between 2 and 8%, or even between 3 and 7% or even between 4 and 6%, relative to the total weight of mineral or vegetable wool and mineral binder.

[0050] The weight content of water-repellent agent, when the latter is present, is preferably between 0.1 and 2%, in particular between 0.5 and 1.8%, or even between 0.7% and 1.6%, relative to the total weight of mineral wool and mineral binder.

[0051] The composition and / or coating therefore preferably comprises 50 to 90% by weight of mineral or vegetable wool, 10 to 50% by weight of mineral binder, 1 to 10% by weight of polymer comprising hydroxyl groups and optionally 0.1 to 2% of water-repellent agent, relative to the cumulative weight of mineral or vegetable wool and mineral binder.

[0052] The total content of any additives in the composition is normally less than 40%, or even 30% and even 20% or 10%, or greater than 0.1%, always relative to the total weight of mineral or vegetable wool and mineral binder. It is preferably at most 5% for redispersible polymer powders and thickeners, and at most 2% for oils. In other words, the total weight proportion of mineral or vegetable wool and mineral binder in the composition or coating is preferably at least 70%, in particular at least 80% and even at least 90%. The additives, or at least some of them, may alternatively be added to the water used for spraying.

[0053] The contents indicated above apply to both the composition and the final coating.

[0054] The composition is mixed with water and the resulting mixture is then deposited on or against a support.

[0055] The deposition of the mixture is preferably carried out by projection. Preferably, the composition is conveyed to a projection nozzle (in dry form), and the water is added as soon as possible at the nozzle outlet. Advantageously, a projection machine is used having a central conduit through which the composition is projected, around which is arranged at least one orifice, in particular a plurality of orifices, through which the water is projected. The mixing of the composition and the water is then carried out at the nozzle outlet, before the mixture reaches the support.

[0056] The amount of water (by weight) relative to the amount of composition is preferably between 0.2 and 1.5, in particular between 0.5 and 1.4, or even between 0.7 and 1.2. The amount of water must be sufficient for the setting and hardening of the binder. It should be adjusted taking into account the fact that the mineral or vegetable wool will absorb some of the water. If the amount of water added is too low, the composition will not adhere sufficiently to the support and will detach. As previously indicated, the water may also contain additives, such as polymers or surfactants. Preferably, the water does not include any adhesive.

[0057] The total flow rate of dry material (mineral or plant wool, mineral binder and any solid additives) is preferably between 1 and 10 kg / min, particularly between 2 and 8 kg / min. The water flow rate is preferably between 5 and 10 l / min. The laying speed is, for example, between 0.1 and 1 m² / min for a covering thickness of 140 mm.

[0058] The support is preferably vertical. It is preferably an exterior wall of a building, and the deposition is carried out on the exterior surface of said wall. An "exterior wall" is understood to mean a wall separating the interior of the dwelling from the exterior. An "exterior surface" is understood to mean the surface facing the exterior of the dwelling. The cladding, thanks to its insulating, mechanical, and aging resistance properties, can then replace the insulating material panels in the ventilated facade and external thermal insulation systems described in the introduction. The wall is advantageously a wall manufactured using an additive manufacturing technique (also called "3D printing"). In such a case, the texturing created by this technique (linked to the fact that layers of mortar are successively deposited one on top of the other) improves the adhesion of the cladding.

[0059] The building element then comprises an exterior wall coated on its outer surface with the insulating coating. The element may also comprise a frame (wood or metal) allowing a facing to be fixed and held at a distance, by providing an air gap between the insulating coating and the facing. The facing may be of any type: glass, metal, wood, PVC, ceramics, etc. Alternatively, the element may comprise a reinforcing coating directly on the insulating coating, generally comprising a reinforcing grid, and a finishing coating or facing.

[0060] The invention is however not limited to this application, and the coating can also be deposited on a horizontal support, for example to insulate a ceiling from below.

[0061] The insulating coating preferably has a thickness of between 30 and 400 mm. A low thickness, for example 30 mm, may be sufficient for fire resistance properties, but will not be sufficient for thermal insulation properties. The thickness of the coating is therefore preferably at least 40 mm and even at least 50 or 60 mm. The spraying technique mentioned above makes it possible to achieve thicknesses of up to 300 mm and more in one pass. The thickness of the coating is therefore advantageously between 60 and 300 mm.

[0062] The density of the coating is preferably between 50 and 250 kg / m 3 , especially between 60 and 200 kg / m 3 The thermal conductivity of the coating is preferably between 35 and 60 mW / mK. When the mineral wool is rock or slag wool, this density is preferably between 100 and 200 kg / m 3, with a thermal conductivity ranging in particular from 37 to 60 mW / mK When the mineral wool is glass wool, the density of the coating is preferably between 50 and 100 kg / m 3 , especially between 60 and 80 kg / m 3 , for thermal conductivities ranging in particular from 35 to 40 mW / mK

[0063] The mechanical resistance of the coating is excellent, with resistances ranging in particular from 5 to 20 kPa in tension, from 5 to 60 kPa in bending (notably from 40 to 60 kPa with slag or rock wool) and from 20 to 110 kPa in compression (notably from 90 to 110 kPa with slag or rock wool).

[0064] The following non-limiting examples illustrate the invention and its advantages.

[0065] Different compositions were sprayed against concrete block, plywood, porcelain stoneware and earthenware walls, with or without adhesion primer. The distance between the spray gun and the wall was 100 to 120 cm. The sprayed thickness was 160 to 180 mm, reduced to 140 mm by removing excess and then smoothing with a trowel. Adhesion to the different substrates was very good.

[0066] Comparative example

[0067] In the comparative example, the projected composition included 66.7% of blown glass wool flakes marketed by Saint-Gobain Isover under the name Comblissimo, 30% of CEM I cement and 3.3% of hemihydrate, plus (in relation to the cumulative weight of glass wool and mineral binder) an addition of 0.4% of cellulose ether (tylose), 0.8% of water-repellent agent (Silres® D) and 1.5% of mineral oil. The dry matter flow rate was 2.5 to 3.5 kg / min and the water flow rate was 6 to 7 L / min.

[0068] Example according to the invention

[0069] The example according to the invention differed from the comparative example in that the composition did not contain tylose and contained an addition of 5% by weight of poly(vinyl alcohol) (Selvol® E575S).

[0070] Table 1 below indicates for each example the density (D) of the coating obtained (in kg / m 3 ), the thermal conductivity (λ) of the coating (in mW / mK), the water absorption, noted W, after 24 h (in kg / m²) measured according to the ISO 29767 standard, the compressive strength (in kPa) and the tensile strength (in kPa).

[0071] MV (kg / m 3 )70-8090λ (mW / mK)3739W -24h (kg / m²)< 1< 1Compression (kPa)15-2020Tension (kPa)2-511

[0072] It was further observed that it was possible to obtain higher coating thicknesses in the case of the example according to the invention. Thicknesses of 300 mm were in particular obtained without difficulty.

Claims

Composition comprising mineral or vegetable wool flakes, a powdered mineral binder and a water-soluble polymer comprising hydroxyl groups, in which the weight content of mineral or vegetable wool is between 50 and 90% and the weight content of mineral binder is between 10 and 50%, relative to the total weight of mineral or vegetable wool and mineral binder. The composition of claim 1, further comprising a water repellent agent. Composition according to one of the preceding claims, in which the mineral wool is chosen from glass wools, slag wools and rock wools. Composition according to one of the preceding claims, in which at least 80% by mass of the mineral or vegetable wool flakes have a size of between 5 and 30 mm, in particular between 6 and 13 mm. Composition according to one of the preceding claims, in which the powdered mineral binder is a hydraulic binder, in particular chosen from the group formed by Portland cements, belitic cements, aluminous cements, sulfoaluminous cements, pozzolanic mixture cements, slags, fly ash, metakaolins, hydraulic lime, sources of calcium sulfate and mixtures of two or more of these hydraulic binders. Composition according to the preceding claim, in which the binder comprises a mixture of Portland cement, a source of calcium sulfate, and optionally aluminous cement. Composition according to one of the preceding claims, in which the polymer comprising hydroxyl groups is a vinyl polymer, in particular is a poly(vinyl alcohol). Composition according to one of the preceding claims, in which the polymer comprising hydroxyl groups is in powder form, the powder preferably having a volume particle size distribution such that the D90 is at most 200 µm. Composition according to one of the preceding claims, further comprising redispersible polymer powders and / or surfactants. Composition according to one of the preceding claims, comprising 50 to 90% by weight of mineral or vegetable wool, 10 to 50% by weight of mineral binder, 1 to 10% by weight of polymer comprising hydroxyl groups and optionally 0.1 to 2% of water-repellent agent, relative to the cumulative weight of mineral or vegetable wool and mineral binder. Method for obtaining an insulating coating on or against a support, comprising mixing a composition according to one of the preceding claims with water and depositing the mixture obtained on or against said support. Method according to the preceding claim, in which the deposition of the mixture is carried out by projection, the composition being conveyed to a projection nozzle, and the water being added as soon as possible at the outlet of the nozzle. Method according to one of claims 11 or 12, in which the support is vertical, in particular is an exterior wall of a building, the deposition being carried out on the exterior surface of said wall. Building element comprising a support coated on one of its surfaces with an insulating coating comprising flakes of mineral or vegetable wool bound together by a hardened mineral binder, and a water-soluble polymer comprising hydroxyl groups, said insulating coating being obtained by the method of at least one of claims 11 to 13. Building element according to the preceding claim, in which the insulating coating has a thickness of between 30 and 400 mm.