Improvement of the adhesion between the insulation and the rendering in systems for the thermal insulation of buildings from the outside

Abstract

The present invention relates to a method for thermally insulating buildings from the outside, comprising (a) attaching an insulating material to the exterior face of the exterior wall of the building to be insulated, and (b) forming a primer layer by applying an adhesion primer to the exterior face of the insulating material, it being possible for these two steps (a) and (b) to be carried out in any order, (c) applying a mortar render to the primer layer, and (d) drying the mortar render, characterized in that the primer layer comprises a cationic polyelectrolyte, an anionic polyelectrolyte and a mineral salt selected from alkali and alkaline earth metal halides and a mineral filler, and in that it has a dry basis weight of less than 200 g / m2.

Description

[0001] Improving adhesion between insulation and coating in external thermal insulation systems for buildings

[0002] The present invention relates to external thermal insulation systems for buildings (ITE) under coating, and in particular the use of a particular primer based on polyelectrolyte coacervates to improve adhesion between the mineral wool-based insulating panel and the first layer of coating.

[0003] External thermal insulation systems for buildings always include a layer of thermal insulation material, such as expanded polystyrene or mineral wool, attached to the exterior wall of the building, either by gluing or, most often, by mechanical means. This layer of insulation material is then covered with a first layer of plaster, which can receive a reinforcing reinforcement, a second layer of plaster, and a finishing layer.

[0004] In such a system, the interface between the insulating material, which is rather hydrophobic and porous, and the first layer of hydrophilic mortar-based coating generally constitutes a point of weakness. It has therefore proven useful to coat the outer surface of the layer of insulating material with an adhesion primer, based on silicates or acrylic polymers.

[0005] The adhesion primers used are liquid products and are generally applied by roller, spray, scraper or brush.

[0006] When the thermal insulation material is mineral wool, its high porosity means that a significant improvement in the adhesion of the first layer of plaster to the mineral wool is only obtained from a fairly high weight of the primer layer, of the order of 200 g / m 2 .

[0007] The present invention is based on the discovery that the amount of primer can be significantly reduced by replacing known primers based on silicates or acrylic polymers with adhesives used until now mainly in the biomedical field.

[0008] The present invention is based more particularly on the idea of ​​using adhesives based on polyelectrolytes with opposite charge polarities, known for several years in the medical and biomedical field under the name of polyelectrolyte complexes / coacervates (PEC) (WO2011 / 149907A1, WO201 1 / 106595,

[0009] WO20 12 / 065148, WO2016 / 011028, WO2019 / 172764), to improve the adhesion of the first layer of coating to the mineral wool-based insulating material in an external thermal insulation (ETI) system under coating.

[0010] When an aqueous solution of an anionic polyelectrolyte (also referred to hereinafter as "polyanion") and an aqueous solution of a cationic polyelectrolyte (also referred to hereinafter as "polycation") are mixed, the polyelectrolytes will immediately associate by electrostatic attraction and form a solid complex (polyelectrolyte complex) which separates from the aqueous phase. When aqueous polymer solutions contain water-soluble salts in an amount sufficient to at least partially mask the opposite charges of the polymers, the attraction between the polyanion and the polycation is reduced and the formation of a solid complex is prevented. When the solutions are mixed, however, a phase separation will be observed with, on the one hand, a concentrated polymer-rich phase, called "coacervate", and, on the other hand, a polymer-depleted supernatant.A detailed description of this phenomenon can be found for example in Wang et al, “The Polyelectrolyte Complex / Coacervate Continuum”, Macromolecules, 2014, 47, 3108-3116.

[0011] The Applicants have discovered that by using primers based on such coacervates of oppositely charged polyelectrolytes, with the addition of significant quantities of mineral fillers, it is possible to significantly reduce the quantity of adhesion primer required and to obtain a satisfactory improvement in the adhesion of the coating to the insulating material for dry weights of less than 200 g / m 2 , and even less than 150 g / m 2 , or even less than 100 g / m 2. An interesting aspect of the low effective grammage of the adhesion primer lies in the low quantity of organic polymer (polyelectrolytes) required to obtain good adhesion of the coating. Indeed, it is the organic fraction of the primer layer, i.e. the quantity of polymer present on the surface of the insulating material, which is mainly responsible for improving the adhesion of the coating. The grammage of polyelectrolytes is generally less than 20 g / m 2 , in particular less than 15 g / m 2 and ideally less than 10 g / m 2 The polyelectrolyte weight is generally greater than 0.1 g / m 2 , or even greater than 1 g / m 2 , or even higher than 2 g / m 2 .

[0012] The present application therefore relates to a method of thermal insulation of buildings from the outside, said method comprising:

[0013] (a) the fixing of insulating material to the external face of the external wall of the building to be insulated, and

[0014] (b) the formation of a primer layer by applying an adhesion primer to the outer face of the insulating material, these two steps (a) and (b) being able to be carried out in any order,

[0015] (c) applying a mortar coating over the primer coat, and

[0016] (d) drying the mortar coating, characterized in that the primer layer comprises a cationic polyelectrolyte, an anionic polyelectrolyte and a mineral salt chosen from alkali and alkaline earth metal halides and a mineral filler, and in that it has a dry weight of less than 200 g / m 2. The adhesion primer is a product, of liquid consistency, containing, as basic ingredients, water, a cationic polyelectrolyte, an anionic polyelectrolyte and a mineral salt chosen from alkali and alkaline-earth metal halides. It can be marketed as is, that is to say in the form of a single-component product, and be applied in the form of a thin layer on the insulating material before or after fixing the insulating material to the wall to be insulated.

[0017] The primer layer is formed by simply applying the adhesion primer to at least one side of the insulating material. The primer layer therefore has an identical composition to the adhesion primer, except that it generally contains less water than the adhesion primer, some or all of the water having evaporated during the partial or complete drying of the primer layer. The primer layer is non-crosslinked. In the primer layer, the cationic polyelectrolyte and the anionic polyelectrolyte are not covalently bonded.

[0018] In an advantageous embodiment of the thermal insulation method of the present invention, the primer layer undergoes complete drying before receiving the mortar coating.

[0019] A primer layer can be formed on only one of the two main faces of the insulation product. This main face bearing the single primer layer is then the so-called "exterior" face of the insulation material. This exterior face is not facing the wall to be insulated and will receive the mortar coating.

[0020] In another embodiment, a primer layer is formed on the two main faces of the insulating material. One of the two primer layers can then be used to improve the fixing of the insulating material to the wall to be insulated, for example by gluing, the other primer layer, applied to the outer face of the insulating material, serving to improve the adhesion of the mortar coating.

[0021] The insulating material bearing a layer of primer, preferably completely dried, on one or both of its main faces can be manufactured in a factory and transported to the site where the thermal insulation work is carried out.

[0022] To the Applicants' knowledge, such a product has never been described and therefore constitutes another subject of the present application. In other words, the present application also relates to a mineral wool panel coated on at least one of its main faces with a primer layer comprising a cationic polyelectrolyte, an anionic polyelectrolyte and a mineral salt chosen from alkali and alkaline earth metal halides, the primer layer having a dry weight of less than 200 g / m 2 .

[0023] The insulating material used in the thermal insulation process is preferably a mineral wool panel, in particular rock wool or glass wool, having a density between 40 and 180 kg / m 3 , especially between 60 and 160 kg / m 3 and ideally between 70 and 150 kg / m 3 . When the mineral wool is rock wool, its density is preferably between 80 and 180 kg / m 3 .

[0024] This insulating material can be fixed to the wall to be insulated by any suitable means, for example by gluing (glue or adhesive mortar) or by anchoring using hammer-in dowels, or by a gluing / anchoring combination.

[0025] As already mentioned, when only one of the faces of the insulating material is coated with a layer of primer, it is the uncoated face of the primer layer which will face the wall to be insulated and will be in contact with it.

[0026] The primer layer, applied to one side or both sides of the insulating material, preferably has a dry weight of less than 150 g / m 2 , in particular a dry weight of less than 100 g / m 2 The tests carried out by the inventors have in fact shown that such low weights of the primer layer were sufficient to significantly improve the adhesion of the mortar coating to the insulating material.

[0027] The dry weight of the primer coat is generally greater than 5 g / m 2 , or even greater than 10 g / m 2 , or even greater than 20 g / m2, for example greater than 50 g / m 2 .

[0028] The inventors also found that, for the same weight, the primers based on polyelectrolyte coacervates of the present invention were significantly more effective than primers based on silicates of the state of the art.

[0029] The adhesion primer and the primer layer further contain a significant amount of a mineral filler. This mineral filler is preferably selected from the group consisting of calcium carbonate, barium sulfate, clay, talc, dolomite, mica, silica sand, ground basalt, kaolin, wollastonite and laponite, with talc being particularly preferred. The mineral filler generally represents from 10 to 80% of the dry weight of the adhesion primer or the primer layer.

[0030] In an advantageous embodiment of the method of the invention, the primer layer contains

[0031] - from 0.1 to 30% by weight, preferably from 0.5% to 20% by weight of cationic polyelectrolyte,

[0032] - from 0.1% to 30% by weight, preferably from 0.5 to 20% by weight of anionic polyelectrolyte,

[0033] - from 1 to 50% by weight, preferably from 10 to 40% by weight of mineral salt chosen from alkali and alkaline earth metal halides, and

[0034] - from 10 to 80% by weight, preferably from 15 to 70% by weight of mineral filler. These percentages being expressed relative to the total dry weight of the primer layer.

[0035] These values ​​are of course also valid for the adhesion primer.

[0036] In a particularly preferred embodiment, the primer layer or the adhesion primer contains from 1 to 3% of cationic polyelectrolyte, from 1 to 3% of anionic polyelectrolyte, from 25 to 35% of mineral salt chosen from alkali metal halides, and from 60% to 70% by weight of mineral filler, these values ​​being relative to the total dry weight of the primer layer or the adhesion primer.

[0037] The water content of the adhesion primer is preferably sufficient to give it a sufficiently low viscosity to allow application by spray, roller, brush or paintbrush. However, it must not exceed a certain lower limit in order to prevent a significant portion of the adhesion primer from flowing into the fibrous insulating material and / or to ensure that the application of the intended grammage can be carried out in a single application, or at most in two applications.

[0038] The water content of the adhesion primer is advantageously between 5 and 90% by weight, preferably between 30 and 70% by weight. High water contents are mainly used in the case of spray application.

[0039] The method according to the invention includes a first embodiment where the application of the adhesion primer to the insulation material is done on site, preferably on the insulation material previously fixed to the wall to be insulated. In this embodiment it may be advantageous to follow the application of the adhesion primer with a step of drying the adhesion primer before applying the mortar coating. Such a drying step is however not essential and the inventors have found that the primer layer improves the adhesion of the mortar coating to the insulating material, even if the primer layer is not previously dried.

[0040] The method according to the invention also includes a second embodiment where the application of the adhesion primer to the insulation material is not carried out on the site of the building to be insulated but for example in a factory where the adhesion primer is applied to one or both faces of the insulating material by an industrial process using automated devices. In this embodiment, the primer layer is of course dried before the coated insulating material is possibly packaged and stored, then shipped to the insulation work site.

[0041] The present application therefore also relates to a method for thermal insulation of buildings from the outside, comprising the fixing of a mineral wool panel coated on at least one of its main faces with a primer layer comprising a cationic polyelectrolyte, an anionic polyelectrolyte and a mineral salt chosen from alkali metal and alkali-earth metal halides, the primer layer having a dry weight of less than 200 g / m 2 In this process, the mineral wool panel is fixed to the exterior face of the exterior wall of the building to be insulated, so that the main face of the mineral wool panel, which carries the primer layer, faces the exterior of the building. This fixing step is followed by the application of a mortar coating over the primer layer and the drying of the mortar coating.

[0042] In the following, the term "polyelectrolyte coacervate" will designate a fluid or viscous aqueous composition containing, dissolved in water, a polyanion, a polycation and a water-soluble mineral salt in a concentration sufficient to prevent the formation of a solid polyelectrolyte complex. In the coacervate, the polyanion and the polycation are not covalently bonded. The term "polyelectrolyte" designates a polymer comprising or consisting of ionic monomers, i.e., monomers carrying positive or negative charges.

[0043] The term "cationic polyelectrolyte" or "polycation" encompasses in the present application a single type of cationic polymer or a mixture of two or more different cationic polyelectrolytes and the term "anionic polyelectrolyte" or "polyanion" encompasses a single type of anionic polymer or a mixture of two or more anionic polyelectrolytes.

[0044] The cationic polyelectrolyte (polycation) and the anionic polyelectrolyte (polyanion) are preferably present in similar amounts, the respective amounts of the anionic and cationic polyelectrolytes being expressed in terms of amounts of charges. Thus, the respective amounts of the anionic and cationic polyelectrolytes are such that the ratio of the number of positive charges present on the cationic polyelectrolyte to the number of negative charges on the anionic polyelectrolyte is between 0.5 and 2, preferably between 0.6 and 1.8, in particular between 0.7 and 1.6, more preferably between 0.8 and 1.4, and most preferably between 0.9 and 1.2.

[0045] The polyelectrolytes may be strong or weak polyelectrolytes. Preferably, at least one of said anionic polyelectrolyte and said cationic polyelectrolyte is a strong polyelectrolyte. In some embodiments, the anionic polyelectrolyte and the cationic polyelectrolyte are both strong polyelectrolytes.

[0046] A strong polyelectrolyte is a polymer whose net charge, positive or negative, is essentially independent of the pH of the composition. In particular, the zeta potential of a strong cationic polyelectrolyte is positive for any pH in the range from 1 to 14 and the zeta potential of a strong anionic polyelectrolyte is negative for any pH in the range from 1 to 14. The potential can be measured using a zeta potential analyzer (e.g., a "zetasizer" device) at a suitable concentration (generally greater than 0.01%, for example, 1% by weight of polyelectrolyte relative to the volume of solution analyzed) and generally at 20°C. Examples of strong cationic polyelectrolytes include polymers comprising a plurality of quaternized amine groups. Strong anionic polyelectrolytes are, for example, polymers comprising a multitude of sulfonate groups (-SO3).Poly(acrylic acid) is an example of a weak anionic polyelectrolyte and non-quaternized polyamines are examples of weak cationic polyelectrolytes, because the net charge of these polymers depends on the pH of the solution.

[0047] In the present application, an anionic polyelectrolyte is a polymer having, at pH 7, a negative net charge and a cationic polyelectrolyte is a polymer having, at pH 7, a positive net charge. This does not mean that an anionic polyelectrolyte comprises only negative charges and is free of positive charges. By analogy, cationic polyelectrolytes can carry both positive and negative charges as long as at pH 7 the overall net charge is positive.

[0048] Therefore, the definition of anionic polyelectrolytes encompasses zwitterionic polyelectrolytes having an isoelectric point (pI) < 7, preferably < 6, and the definition of cationic polyelectrolytes encompasses zwitterionic polyelectrolytes having an isoelectric point > 7, preferably > 8. The most well-known zwitterionic polyelectrolytes are proteins or polypeptides comprising both carboxylate (-COO) side groups and amino (-NH2) side groups.

[0049] In a preferred embodiment of the method of the present invention the anionic polyelectrolyte comprises only negative charges and is free of positive charges and the cationic polyelectrolyte comprises only positive charges and is free of negative charges.

[0050] The cationic groups of the cationic polyelectrolyte are, for example, primary amine, secondary amine, tertiary amine or quaternized ammonium groups, located in the main chain of the polymer or on the side groups.

[0051] The cationic polyelectrolyte is preferably selected from the group consisting of

[0052] - poly(diallyldimethylammonium chloride),

[0053] - poly[(2-hydroxypropyl)dimethylammonium chloride],

[0054] - polyamidoamine-epichlorohydrin (PAAE),

[0055] - polyethyleneimine,

[0056] - poly(acrylamide-co-diallyldimethylammonium chloride),

[0057] - copolymer of hydroxyethylcellulose and poly(diallyldimethylammonium chloride) (Polyquaternium-4),

[0058] - copolymer of acrylamide and dimethylaminoethyl methacrylate quaternized with dimethyl sulfate (Polyquaternium-5, CAS 26006-22-4),

[0059] - copolymer of dimethylaminomethyl methacrylate and alkyl methacrylate,

[0060] - chitosan,

[0061] - quaternized poly(N,N-(dimethylamino)ethyl methacrylate),

[0062] - guar hydroxypropyltrimonium chloride,

[0063] - poly(N,N-dimethyl-3,5-dimethylene piperidinium chloride),

[0064] - poly(vinylbenzyltrimethylammonium chloride),

[0065] - poly(3-(methacryloylamino)propyl-trimethylammonium chloride], poly([2-(methacryloloxy)ethyl]-trimethylammonium chloride),

[0066] - polyvinylamine (PVA),

[0067] - poly(N,N-dimethyl-3,5-dimethylene piperidinium chloride) (PDDPC),

[0068] - poly(vinylbenzyltrimethylammonium chloride) (PVBTAC),

[0069] - poly(allylamine chloride) (PAH), and - poly[3-(methacryloylamino)propyltrimethylammonium chloride] (PMAPTAC),

[0070] - cationic dextran.

[0071] The anionic groups of the anionic polyelectrolyte are, for example, selected from the group consisting of carboxyl, sulfonate, phosphonate, boronate, sulfate, borate and phoshate residues. They can be located in the main chain of the polymer or on the side groups.

[0072] In an advantageous embodiment, the anionic polyelectrolyte is selected from the group consisting of poly(acrylic acid), poly(acrylic acid-co-acrylamido), poly(sodium 4-styrenesulfonate), lignosulfonate, sodium humate, alginate, poly(sodium 2-acrylamido-2-methyl-1-propanesulfonate), hyaluronic acid, dextran sulfate and poly(sodium vinylsulfonate).

[0073] In a preferred embodiment, at least one of the polyelectrolytes is a linear polymer, the other polyelectrolyte, of opposite charge, being able to be linear or branched. In other words, the anionic polyelectrolyte and / or the cationic polyelectrolyte can be linear polymers, free of branches.

[0074] The anionic and cationic polyelectrolytes have a weight-average molecular mass (determined by light scattering) of between 1,000 and 2,000,000, preferably between 50,000 and 700,000 Da, in particular between 100,000 and 400,000 Da.

[0075] The weight average molecular weight of the anionic polyelectrolyte is advantageously similar to that of the cationic polyelectrolyte. More precisely, the ratio of the weight average molecular weight of the anionic polyelectrolyte to the weight average molecular weight of the cationic polyelectrolyte is preferably between 0.4 and 1.6, more particularly between 0.7 and 1.3 and ideally between 0.8 and 1.2. The primer layer formed on the thermal insulation material may be reinforced by a reinforcement system based on polyphenols and transition metals.

[0076] Indeed, the mechanical performance of the dry primer layer is generally improved when small amounts of water-soluble polyphenol(s) are added to the oppositely charged polyelectrolyte coacervate. The water-soluble polyphenol acts as a reinforcing agent and its effectiveness is further increased when combined with very small amounts of a transition metal. The mechanisms involved in this reinforcing effect are probably hydrogen bonds, possibly associated with ligand-metal coordination bonds. These two types of bonds are not covalent bonds and their existence or strength depends on environmental conditions such as pH and / or ionic strength.

[0077] The adhesion primer and the primer layer may therefore further contain at least one water-soluble polyphenol comprising at least one polyhydroxylated aromatic ring, preferably at least two and in particular at least three polyhydroxylated aromatic rings.

[0078] The term "polyphenol" refers to an organic compound comprising at least one polyhydroxylated aromatic ring, i.e. bearing at least two hydroxyl groups (-OH) on the same cyclic structure. A "water-soluble polyphenol" is a polyphenol having a solubility in distilled water at 20°C of at least 100 g / L.

[0079] The amount of water-soluble polyphenol is advantageously between 0.0001 and 0.1% by weight, preferably between 0.01% and 0.05% by weight, more preferably between 0.05% and 0.10% by weight, relative to the total dry weight of the primer layer or to the total dry weight of the adhesion primer. In a preferred embodiment, at least a portion of the polyphenols used comprise at least two, preferably at least three and more preferably at least four polyhydroxylated aromatic rings.

[0080] The polyhydroxylated aromatic rings are preferably selected from the group consisting of catechol, pyrogallol and tetrahydroxylated or pentahydroxylated aromatic rings.

[0081] In a particularly interesting embodiment, the polyphenol is tannic acid (CAS No. 1401-55-4) which has five trihydroxylated aromatic ring structures. It is a relatively inexpensive, bio-sourced ingredient with a high concentration of polyhydroxylated aromatic rings.

[0082] More recently, synthetic organic polymers made from monomers with polyhydroxylated aromatic rings have been described (see for example the work of Cheng et al. in Nature Communications, 13, article no. 1892 (2022)). They could very effectively reinforce the primer layer of the present invention.

[0083] Therefore, in another advantageous embodiment of the method of the present invention, the polyphenol used as a reinforcing agent is a synthetic copolymer comprising comonomers with polyhydroxylated aromatic structures, preferably a copolymer of styrene and a comonomer selected from the group consisting of dihydroxystyrene, trihydroxystyrene, tetrahydroxystyrene and pentahydroxystyrene.

[0084] The mechanical performance of the dried primer layer can be further improved by combining the polyphenol-reinforced polyelectrolytes with polyvalent transition metal ions. The adhesion primer and the primer layer therefore advantageously further comprise at least one water-soluble salt of a transition metal, preferably a salt of iron, zinc, cobalt, copper or vanadium.

[0085] The water-soluble salt(s) of a transition metal are advantageously used in a total quantity of between 0.0001 and 0.1%, preferably between 0.005 and 0.05%, these percentages being expressed relative to the total dry weight of the primer layer or relative to the dry weight of the adhesion primer.

[0086] The weight ratio of transition metal salt to water-soluble polyphenol(s) is typically between 0.1 and 0.2, preferably between 0.12 and 0.18.

[0087] The transition metals are preferably selected from the group consisting of iron (Fe), zinc (Zn), cobalt (Co), copper (Cu) and vanadium (V). Halides, particularly chlorides and bromides, are preferred anions of the transition metal salts used in association with polyphenols.

[0088] The water-soluble salt of a transition metal is iron trichloride (FeCl3).

[0089] The inventors obtained particularly interesting results by using the combination of tannic acid (polyphenol) and iron trichloride to reinforce the mechanical properties of the primer layer.

[0090] To prepare the adhesion primer, a polyelectrolyte coacervate is first prepared to which the mineral filler(s) and possibly other additives are then added.

[0091] The polyelectrolyte coacervate composition can be prepared by dissolving each of the cationic and anionic polyelectrolytes separately in an aqueous solution of an inorganic salt of an alkali or alkaline earth metal, preferably a halide of an alkali or alkaline earth metal. The salt concentration of the aqueous solution is typically between 0.05 and 6 mol / L, preferably between 0.2 and 2.5 mol / L, and in particular between 0.5 and 2.0 mol / L. The higher the average molecular weight of the polyelectrolytes, the greater the ionic strength of the salt solution must be. Thus, for weight average masses below 100,000 Da, salt concentrations between 0.2 and 1 mol / L are generally sufficient. To dissolve polyelectrolytes with weight average masses greater than 400,000 for the formation of a polyelectrolyte coacervate, salinities greater than 1.8 mol / L are required.

[0092] The pH of the two polyelectrolyte saline solutions is advantageously acidic, preferably between 1 and 3, better between 1 and 2.

[0093] After the anionic and cationic polyelectrolytes have completely dissolved, the two solutions are simply mixed together. A dense, polymer-rich lower phase, called the "coacervate," then separates from an upper, polymer-depleted phase, called the "supernatant." The two phases can be easily separated from each other, possibly after centrifuging the mixture.

[0094] On an industrial scale, it is of course interesting to reduce the volume fraction of the supernatant phase as much as possible, or even to prepare a coacervate without the formation of a supernatant phase. This can be achieved by increasing the concentration of polyelectrolytes and the concentration of salts (halide of an alkali or alkaline-earth metal) of the two solutions before mixing.

[0095] The solids fraction (polyelectrolytes, salts and additives) of the coacervate composition is typically between 20% and 35% by weight, preferably between 25% and 30% by weight.

[0096] The salt concentration of the polyelectrolyte coacervate composition is advantageously between 10% and 50% by weight, preferably between 15% and 45% by weight. The polyelectrolyte content of the polyelectrolyte coacervate composition is between 1% and 30% by weight, preferably between 3% and 20% by weight, in particular between 4% and 15% by weight.

[0097] When polyphenols are used to strengthen the polyelectrolyte complex, they are advantageously added to the cationic polyelectrolyte solution, either before or after dissolving the polyelectrolyte. Adding polyphenols to the anionic polyelectrolyte solution often results in the undesirable formation of a gel. The polyphenols can be added as such or can be pre-dissolved in an aqueous solution of the mineral salt of an alkali or alkaline earth metal.

[0098] When a water-soluble salt of a transition metal is additionally used, the latter is preferably added to the solution containing the cationic polyelectrolyte and the polyphenol.

[0099] The pH of the coacervate can then be adjusted to a value between 5 and 9, preferably between 6 and 8.

[0100] The mineral filler is preferably added to the coacervate after adjusting the pH to a value close to neutral. For this, the mineral filler is dispersed either directly in the coacervate or first in an aqueous solution of a mineral salt chosen from alkali and alkaline earth metal halides, preferably having an ionic strength similar to that of the coacervate, the suspension thus obtained then being added to the coacervate. A dispersing agent of the polymer type or surfactant is advantageously used to facilitate this dispersion step.

[0101] Various additives such as pigments, dyes, biocidal agents, antifoaming agents, flame retardants, hydrophobic agents (e.g. silicone type) may also be added to the coacervate in a maximum total quantity equal to 20% by weight, preferably 20% by weight and ideally 5% by weight, based on the weight of the polyelectrolytes and mineral salts of alkali or alkaline earth metal. Example

[0102] Preparation of the polycation saline solution:

[0103] A concentrated aqueous solution of tannic acid having a concentration of 0.14 g / mL is prepared. 48 μL of the concentrated tannic acid solution is added to 15.9 mL of water using a micropipette, acidified by adding HCl (1 M) to pH = 1, and then 5.45 g of KBr is added. 3.4 g of EVA 462 (polydiallyldimethylammonium chloride, PDADMAC) is then added to the aqueous composition obtained and the polyelectrolyte is stirred until complete dissolution of the polycation. After dissolution of the polycation, 1.1 mg of FeCl3 is added, with stirring.

[0104] Preparation of the polyanion saline solution:

[0105] 5.45 g of KBr are added to 16.7 ml of water previously acidified to pH 1 with HCl. 2.42 g of Versai TL 130, having a polystyrene sulfonate (PSS) content of approximately 30% (Nouryon) are added to the resulting saline acid solution.

[0106] Preparation of the coacervate:

[0107] After complete dissolution of the polyelectrolytes, the polyanion solution (polystyrene sulfonate, PSS) is poured into the polycation solution (polydiallyldimethylammonium chloride, PDADMAC) with vigorous stirring. The mixture is allowed to stand for a few minutes. If phase separation is observed, the upper phase (supernatant) is discarded. The lower phase (coacervate) is green in color and changes color (red) when neutralized by adding 0.3 mL of AMP 95 (ANGUS Chemical Company) to pH > 5.

[0108] Preparation of the adhesion primer:

[0109] Using a disperser (Dispermat®), 70 g of talc are dispersed in 10 mL of an aqueous KBr solution (1.8 mol / L) additionally containing 10% by weight of a dispersing agent (Disperbyk 191, polyacrylate).

[0110] The aqueous talc dispersion obtained is then mixed with 120 g of coacervate and stirred for 10 min at 3000 rpm until an adhesion primer composition having the following composition is obtained: 46% water, 17% salt, 0.79% polycation, 0.85% polyanion, 0.008% tannic acid, 0.0013% FeCl3 and 35% talc.

[0111] The adhesion primer is then applied using a brush to one side of a mineral wool panel (Clima 34, Saint-Gobain Isover) with a density of approximately 55 kg / m 3 The application surface is delimited by a rectangular stencil. The weight of the primer layer varies from approximately 70 g / m 2 at about 300 g / m 2 The primer coat is dried for 24 hours at room temperature.

[0112] A layer of mortar plaster with a thickness of approximately 3 mm is then applied through the same rectangular stencil. The adhesion of the plaster to the insulation material is tested immediately after application (fresh adhesion) and after 14 days of curing.

[0113] Fresh Membership:

[0114] The adhesion of fresh plaster is measured by placing an aluminum disc (diameter 6 cm) weighed down with a 5 kg weight on it for 10 seconds. After removing the aluminum disc, the amount of plaster removed by the disc is determined by weighing. The greater the mass of plaster removed by the disc, the poorer the adhesion in the fresh state.

[0115] Table 1 shows the mass of coating carried away by the disc for different (dry) grammages of the primer layer. The second column shows the polyelectrolyte content (dry weight) of the different adhesion primers used and the third column the polyelectrolyte grammage obtained.

[0116] Each test was carried out twice and the last column shows the average mass (two samples) of coating carried away by the disc. [Table 1]

[0117] It can be seen that the application of a primer layer based on polyelectrolyte coacervate makes it possible to significantly reduce the quantity of fresh coating carried away by the aluminum disc, i.e. to improve the adhesion of the fresh coating to the insulation material, even for a grammage of less than 100 g / m 2 .

[0118] For comparison, when the adhesion primer based on polyelectrolyte coacervate is replaced by an adhesion primer containing an equivalent quantity of acrylic polymer (Weber.prim Universal), the quantity of fresh coating removed is approximately 7 g for a primer weight of 200 g / m 2 .

[0119] Adhesion of the cured coating

[0120] After the plaster has completely cured (14 days), square samples of 20 cm on each side are cut to a depth of approximately 2 - 3 mm. The samples are then glued, with their untreated side, to a plywood panel (18 mm) using an epoxy adhesive (SABA Wellfix®). The adhesion strength of the cured plaster to the insulation material is measured by subjecting the samples to a plaster layer peel test using a portable adhesion tester (M2015, BPS Wennigsen). The results obtained show that the primer layer neither significantly improves nor degrades the adhesion of the dry plaster to the insulation material.

Claims

CLAIMS 1. Method of thermal insulation from the outside of buildings comprising (a) the fixing of insulating material to the external face of the external wall of the building to be insulated, and (b) the formation of a primer layer by applying an adhesion primer to the outer face of the insulating material, these two steps (a) and (b) being able to be carried out in any order, (c) applying a mortar coating over the primer coat, and (d) drying the mortar coating, characterized in that the primer layer comprises a cationic polyelectrolyte, an anionic polyelectrolyte and a mineral salt chosen from alkali and alkaline earth metal halides and a mineral filler, and in that it has a dry weight of less than 200 g / m 2 .

2. Method according to claim 1, characterized in that the insulating material is a mineral wool panel, in particular rock wool or glass wool, having a density of between 40 and 180 kg / m 3 .

3. Method according to claim 1 or 2, characterized in that the primer layer has a dry weight of less than 150 g / m 2 , preferably a dry weight of less than 100 g / m 2 .

4. Method according to any one of the claims, characterized in that the primer layer contains from 0.1 to 30% by weight, preferably from 0.5% to 20% by weight of cationic polyelectrolyte, from 0.1% to 30% by weight, preferably from 0.5 to 20% by weight of anionic polyelectrolyte, from 1 to 50% by weight, preferably from 10 to 40% by weight of mineral salt chosen from alkali and alkaline earth metal halides, and from 10 to 80% by weight, preferably from 15 at 70% by weight of mineral filler, these percentages being expressed in relation to the total dry weight of the primer layer.

5. Method according to the preceding claim, characterized in that the primer layer contains from 1 to 3% of cationic polyelectrolyte, from 1 to 3% of anionic polyelectrolyte, from 25 to 35% of mineral salt chosen from alkali metal halides, and from 60% to 70% by weight of mineral filler.

6. Method according to any one of the preceding claims, characterized in that the adhesion primer has a water content of between 5 and 90% by weight, preferably between 30 and 70% by weight.

7. Method according to any one of the preceding claims, characterized in that the mineral filler is chosen from the group consisting of calcium carbonate, barium sulfate, clay, talc, dolomite, mica, silica sand, ground basalt, kaolin, wollastonite and laponite.

8. Method according to any one of the preceding claims, characterized in that the cationic polyelectrolyte is chosen from the group consisting of - poly(diallyldimethylammonium chloride), - poly[(2-hydroxypropyl)dimethylammonium chloride], - polyamidoamine-epichlorohydrin (PAAE), - polyethyleneimine, - poly(acrylamide-co-diallyldimethylammonium chloride), - copolymer of hydroxyethylcellulose and poly(diallyldimethylammonium chloride) (Polyquaternium-4), - copolymer of acrylamide and dimethylaminoethyl methacrylate quaternized with dimethyl sulfate (Polyquaternium-5, CAS 26006-22-4), - copolymer of dimethylaminomethyl methacrylate and alkyl methacrylate. - chitosan, - quaternized poly(N,N-(dimethylamino)ethyl methacrylate), - guar hydroxypropyltrimonium chloride, - poly(N,N-dimethyl-3,5-dimethylene piperidinium chloride), - poly(vinylbenzyltrimethylammonium chloride), - poly[3-(methacryloylamino)propyl-trimethylammonium chloride], poly([2-(methacryloloxy)ethyl]-trimethylammonium chloride), - polyvinylamine (PVA), - poly(N,N-dimethyl-3,5-dimethylene piperidinium chloride) (PDDPC), - poly(vinylbenzyltrimethylammonium chloride) (PVBTAC), - poly(allylamine chloride) (PAH), and - 3-(methacryloylamino)propyltrimethylammonium polychloride] (PMAPTAC), - cationic dextran.

9. Method according to any one of the preceding claims, characterized in that the anionic polyelectrolyte is chosen from the group consisting of poly(acrylic acid), poly(acrylic acid-co-acrylamido), poly(sodium 4-styrenesulfonate), lignosulfonate, sodium humate, alginate, poly(sodium 2-acrylamido-2-methyl-1-propanesulfonate), hyaluronic acid, dextran sulfate and poly(sodium vinylsulfonate).

10. Method according to any one of the preceding claims, characterized in that the primer layer further contains a water-soluble polyphenol comprising at least one polyhydroxylated aromatic cycle, preferably at least two and in particular at least three polyhydroxylated aromatic cycles, in an amount of between 0.0001 and 0.1% by weight, preferably between 0.01 and 0.05% by weight, more preferably between 0.05 and 0.10% by weight, relative to the total dry weight of the primer layer.

11. Method according to the preceding claim, characterized in that the polyhydroxylated aromatic cycles of the water-soluble polyphenol are catechol or pyrogallol residues, or tetrahydroxylated or pentahydroxylated aromatic cyclic structures.

12. Method according to claim 10 or 11, characterized in that the water-soluble polyphenol comprising at least one polyhydroxylated aromatic cycle is tannic acid.

13. Method according to any one of the preceding claims, characterized in that the primer layer further contains at least one water-soluble salt of a transition metal, preferably a salt of iron, zinc, cobalt, copper or vanadium, in an amount of between 0.0001% and 0.1% by weight, preferably between 0.005 and 0.05% by weight, relative to the total dry weight of the primer layer.

14. Mineral wool panel preferably having a density between 40 and 180 kg / m 3 , said mineral wool panel being coated on at least one of its main faces with a primer layer comprising a cationic polyelectrolyte, an anionic polyelectrolyte, a mineral salt chosen from alkali and alkaline-earth metal halides, and a mineral filler, the primer layer having a dry weight of less than 200 g / m 2 .

15. A method of external thermal insulation of buildings comprising fixing a mineral wool panel according to claim 14 to the external face of the external wall of the building to be insulated, so that the main face of the mineral wool panel which carries the primer layer is facing the exterior of the building, applying a mortar coating to the primer layer and drying the mortar coating.

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