WO2025012260A1 - Sealing composition based on polyurethane and poly(vinyl acetal) - Google Patents

Abstract

The present invention relates to a composition for sealing different substrates such as substrates made of cementitious material. It also relates to a sealing coating, in particular a waterproofing coating, formed from a composition of said type. It further relates to a method for sealing a roof, terrace, balcony, plumbing unit, facade or swimming pool by forming a coating of said type.

Description

Description

Title: Sealing composition based on polyurethane and poly(vinyl acetal)

The present invention relates to a composition for waterproofing various substrates such as substrates made of cementitious material. It also relates to a waterproof coating, in particular a water-proof coating, formed from such a composition. It further relates to a method for waterproofing a roof, a terrace, a balcony, a damp room, a facade or even a swimming pool, via the formation of such a coating.

The waterproofing of roofs, terraces, balconies, damp rooms, swimming pools or facades is essential to ensure the durability of constructions.

To achieve this, numerous waterproofing systems have been developed. These include bituminous membranes and thermoplastic or vulcanized synthetic membranes that are assembled by welding, hot-poured asphalt coatings or systems known in the art as "liquid waterproofing systems" (SEL).

These are made of polymer resin-based materials implemented in one or more layers by projection or by application with a roller, brush or squeegee. Different types of resins are used, in particular polyesters, acrylics, neoprene bitumens, or polyurethane resins. Very durable and easy to apply, these systems generally allow pedestrian traffic directly after drying, eliminating the need for heavy protection.

The invention aims to propose new sealing coatings which are as efficient, from the point of view of sealing and mechanical properties, as the systems known to date, but which also have rapid drying, good water resistance, good adhesion to the substrate and good resistance to aging (in particular the maintenance of flexibility and little or no yellowing). Another aim of the invention is to propose sealing coatings having a lower carbon footprint.

SUMMARY OF THE INVENTION For this purpose, the present invention relates to a sealing composition (or equivalently "sealing system composition"), which is an aqueous dispersion comprising: water, poly(vinyl acetal)-based resin particles, polyurethane-based resin particles, one or more plasticizers, and one or more emulsifiers, in which the total content of resin particles is 5 to 50% by weight.

In some embodiments, the poly(vinyl acetal)-based resin is poly(vinyl butyral)-based.

In some embodiments, the poly(vinyl butyral) based resin includes residual alcohol and acetate functionalities.

In some embodiments, the poly(vinyl butyral)-based resin is derived from the recycling of laminated glazing.

In certain embodiments, the composition of the invention further comprises one or more fillers, the filler content preferably being between 5 and 80% by weight, relative to the total weight of the composition.

In some embodiments, the fillers are selected from calcium carbonate, calcium stearate, clays, talc, dolomite, mica, silica sands, ground basalt, barium sulfate, kaolin, and mixtures of two or more of these compounds.

In some embodiments, the composition of the invention further comprises from 0.1 to 20% by weight of pigments, relative to the total weight of the composition.

In some embodiments, the total weight content of emulsifier(s) is between 0.1% and 10%.

In some embodiments, the plasticizer content is between 5% and 30% by weight, preferably between 10% and 25% by weight, relative to the total dry weight of resin.

In certain embodiments, the amount of water is between 10 and 70% by weight, in particular between 20 and 60% by weight, relative to the total weight of the composition.

In some embodiments, the weight ratio of the polyurethane-based resin particle content to the poly(vinyl acetal)-based resin particle content is between 0.05 and 20, preferably between 0.1 and 2, or even between 0.2 and 0.8.

In some embodiments, said polyurethane is an anionic polyurethane comprising pendant carboxylate groups COO M ⁺ where M ⁺ is a cation resulting from neutralization of the carboxylic groups by a base. In certain embodiments, the composition of the invention further comprises one or more crosslinking agents, the weight ratio between the content of crosslinking agent and the content of poly(vinyl acetal)-based resin preferably being between 0.001 and 0.10, in particular between 0.002 and 0.06.

It also relates to a waterproof coating, obtained by applying and drying a composition as defined in the present application.

Another object of the present invention is the use of a sealing coating as defined in the present application, as a sealing coating for water, in particular for chlorinated water.

Another subject of the present invention is a method for waterproofing a roof, a terrace, a balcony, a wet room, a facade, or a swimming pool comprising the application, on a substrate of said roof, terrace, balcony, wet room, facade, or swimming pool, of a composition as defined in the present application to form a coating, then the drying of said coating to obtain a dry coating preferably having a thickness ranging from 0.1 to 2 mm. In certain embodiments, said substrate is made of cementitious material, optionally covered with a primer, for example an epoxy primer.

The inventors have indeed demonstrated that, surprisingly, the combination of a polyurethane-based resin and a poly(vinyl acetal)-based resin leads to a stable composition that can form a waterproof coating having one or more of the aforementioned advantages. A synergy has even been observed, particularly for adhesion performance.

DETAILED DESCRIPTION

The sealing composition according to the invention (in particular, water-based sealing) is an aqueous dispersion comprising: water, resin particles based on poly(vinyl acetal), polyurethane-based resin particles, one or more plasticizers, and one or more emulsifiers, wherein the total resin particle content is 5 to 50% by weight (e.g., 7 to 48%, especially 10 to 45%, or even 15 to 40%, or even 20 to 35%).

Preferably, the poly(vinyl acetal) based resin is based on poly(vinyl butyral), also called PVB.

Preferably, the poly(vinyl acetal)-based resin, in particular poly(vinyl butyral)-based resin, is made of poly(vinyl acetal), in particular poly(vinyl butyral).

Preferably, the resin based on poly(vinyl acetal), in particular poly(vinyl butyral), comprises residual alcohol and acetate functions. These residual functions come from the resin manufacturing process, which is generally done by hydrolysis of poly(vinyl acetate) into poly(vinyl alcohol) and then acetalization of the latter. The presence of alcohol functions makes it possible in particular to crosslink the resin and improve its properties. The resin based on poly(vinyl butyral) is advantageously derived from the recycling of laminated glazing. The latter in fact use PVB as a lamination interlayer between two sheets of glass. The use of recycled materials makes it possible to reduce the carbon footprint of the sealing system.

The resin content by weight corresponds to the mass percentage of resin in dry extract in the composition (or equivalently “in the aqueous dispersion”), therefore to the weight of resin relative to the total weight of the composition. Generally speaking, unless otherwise stated, the contents of the various constituents of the composition are given by weight, relative to the total weight of the composition.

The composition further comprises particles of a polyurethane-based resin, preferably a resin consisting of polyurethane.

Resins based on (or consisting of) polyurethane are well known to those skilled in the art, and their preparation is described in particular in US 7,345,110. The polyurethane is typically ionic (i.e. cationic or anionic). Preferably, it is an anionic polyurethane comprising carboxylate groups COO M ⁺ or SO3'I I ⁺ where M ⁺ is a cation. In certain embodiments, M ⁺ is a cation resulting from a neutralization of the groups corresponding acids (ie COOH and SO3H respectively) by a base. In some embodiments, M ⁺ is an alkali cation (eg sodium).

More preferably, it is an anionic polyurethane comprising pendant carboxylate groups COO M ⁺ where M ⁺ is a cation resulting from the neutralization of the carboxylic groups by a base. In general, such a polyurethane can be formed by a three-step process:

- a step (i) of forming a carboxylated isocyanate prepolymer by reacting one or more polyols with a stoichiometric excess of one or more diisocyanates, and with one or more hydroxylated or amino carboxylic acids,

- a step (ii) of neutralization with a base and emulsification in water, and

- a step (iii) of chain extension by addition of a chain extension agent (e.g. polyamine, in particular a diamine or a polyol, in particular a diol).

Such a preparation process is advantageously carried out in the absence of any organic solvent. In certain embodiments, the process is carried out in the presence of coalescing agents, in particular a pyrrolidone such as N-methyl-2-pyrrolidone or N-butyl-2-pyrrolidone.

The diisocyanate may more particularly be an aliphatic diisocyanate (e.g. cyclic or acyclic aliphatic) or an aromatic diisocyanate.

Examples of aliphatic diisocyanates include: 1,6-hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), methylene bis-(4-cyclohexylisocyanate) (HMDI), pentamethylene diisocyanate (PDI), 4-hexahydrotoluene diisocyanate, 2,6-hexahydrotoluene diisocyanate, dicyclohexylmethane diisocyanate, tetramethylxylene diisocyanate, norbornane diisocyanate, bis-(isocyanatomethyl)cyclohexane, tetramethylene-1,4-diisocyanate, cyclohexane-1,4-diisocyanate, 1,12-dodecane diisocyanate, and 2,2,4-trimethylhexamethylene diisocyanate.

Examples of aromatic diisocyanates include: 2,2'-diphenylmethylene diisocyanate (2,2'-MDI), 4,4'-diphenylmethylene diisocyanate (4,4'-MDI), 4,4'-dibenzyl diisocyanate (4,4'-DBDI), 2,6-toluene diisocyanate (2,6-TDI), m-xylylene diisocyanate (m-XDI), 2,4'-diphenylmethylene diisocyanate (2,4'-MDI), 2, 4'-dibenzyl diisocyanate (2,4'-DBDI), or 2,4-toluene diisocyanate (2,4-TDI).

The term “polyol” means any organic compound comprising at least two hydroxy functions. The polyol may in particular be an aliphatic or aromatic polyol, saturated or unsaturated, linear or branched, and cyclic or acyclic.

The polyol is preferably selected from the group consisting of a polyether polyol (e.g. polyethylene glycol, polypropylene glycol), a polyester polyol and a polycarbonate polyol.

Polyether polyols can be obtained by the polymerization of a cyclic oxide, for example propylene oxide, ethylene oxide, trimethylene oxide, tetrahydrofuran, 3-methyl tetrahydrofuran or by the addition of one or more of these oxides to initiators such as for example water, ethylene glycol, propylene glycol, diethylene glycol, glycerol, cyclohexane-dimethanol, trimethylolpropane, pentaerythrityl, bisphenol A. Thus, examples of linear or branched polyether polyols are polypropylene glycol, polyethylene glycol, polytetramethylene glycol or poly(ethylene/propylene) glycol.

Examples of aliphatic or aromatic polyester polyols are ester glycols with one or more alcohol functions which are obtained by condensation of polycarboxylic acids such as malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, phthalic anhydride, with polyols. Examples of polyols for preparing polyester polyols are ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, diethylene glycol, 1,5-pentanediol, 1,6-hexanediol, glycerol, trimethylolpropane, pentaerythritol, cyclohexanedimethanol or 1,8-octanediol. Polyester polyols can also be obtained by the polymerization of lactones such as caprolactone.

Polyester polyols can also be obtained from unsaturated fatty acids such as oleic acid, linoleic acid, licanic acid, arachidonic acid, ricinoleic acid or linoleic acid from, for example, linseed, soybean, sunflower, rapeseed or herring oil.

Polycarbonate polyols can be obtained by esterification of carbonic acid with a diol or a polyol. Polycarbonate polyols can also be obtained by reaction of phosgene or carbonates, such as diethyl carbonate or diphenyl, with a diol or a polyol. Examples of polyols are ethylene glycol, propylene glycol or glycerol.

The number-average molar masses of the polyols used are generally between 300 and 10,000, or more particularly between 400 and 8,000, or between 500 and 5,000 (number-average molar masses determined by gel permeation chromatography, also called size exclusion chromatography).

Low molar mass polyols, typically between 60 and 300, can also be used in the synthesis of the carboxylated prepolymer. Examples of low molar mass polyols are ethylene glycol, propylene glycol, 1,2- and 1,3-propanediol, 1,2-, 1,3-, and 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, glycerol, neopentyl glycol, trimethylol propane, pentaerythritol, cyclohexane dimethanol, 1,2- and 1,4-cyclohexanediol, 1,8-octanediol, diethylene glycol, triethylene glycol, dipropylene glycol, tripropylene glycol.

The hydroxylated or amino carboxylic acid is typically of formula (I), (II) or (III): (HO) _X Q(COOH) _Z (I)

(HO) _x (HpN) _y Q(COOH) _z (ll)

(HpN) _y Q(COOH) _z (III) where Q is a hydrocarbon residue and x, y and z are integers from 1 to 3 and p an integer from 1 to 2.

It is preferable that x+y be greater than or equal to 2, preferably equal to 2.

Examples of hydroxylated carboxylic acids are 2,2-bis(hydroxymethyl)-propionic acid (DMPA), 2,2-bis(hydroxymethyl)-butyric acid (DMBA), tartaric acid, 2-(bis(2-hydroxyethyl)amino)acetic acid, 3-[bis(2-hydroxyethyl)amino]propanoic acid or N,N-Bis(2-hydroxyethyl)alanine.

Examples of amino carboxylic acids are ethylenediamine-N,N'-diacetic acid, alanine or glycine. Examples of amino and hydroxy carboxylic acids are N-(2-hydroxyethyl)-|3-alanine, threonine or serine.

Optionally, step (i) may take place in the presence of a catalyst. Examples of catalysts are metal complexes such as tin complexes such as dibutyltin dilaurate (DBTDL), dicotyltin dilaurate (DOTDL), tin octanoate or bismuth carboxylate, zinc carboxylate, or amines. tertiary such as triethylamine, 1,4-diazabicyclo[2.2.2]octane (DABCO), 1,8-diazabicyclo(5.4.0)undec-7-ene (DBU) or 2,4,6-tris(N,N-dimethylaminomethyl)phenol (DMP-30). In this case the catalyst is generally present in a concentration of 0.01 to 0.2%, or 0.02 and 0.1% relative to the weight of the carboxylated prepolymer.

In step (i), the NCO/OH ratio is generally between 1.2 and 5, in particular between 1.4 and 3, the hydroxyl groups being those of the polyols, and of the hydroxylated carboxylic acid. In the case where an amino carboxylic acid is used, the NCO/(OH+NH) ratio is generally between 1.2 and 5, in particular between 1.4 and 3.

The carboxylated prepolymer with isocyanate end groups thus obtained is then neutralized with a base which is non-reactive with respect to isocyanates and capable of neutralizing the carboxylic acid functions, typically a tertiary amine. In certain embodiments, said base is volatile. The adjective "volatile" here designates compounds having (at atmospheric pressure) a boiling point of less than 200°C, preferably less than 120°C.

Examples of bases for neutralization of the prepolymer are trimethylamine, triethylamine, triisopropylamine, N,N-dimethylisopropylamine, N-methyl-diisopropylamine, N-ethyldiisopropylamine, N,N-dimethylcyclohexylamine, N-ethylmaleimide, N-methylmorpholine, N-ethylmorpholine, 1,4-dimethylpiperazine or N-methylpiperidine.

The base for neutralization is generally added such that the neutralization rate of the -COOH functions is between 50 and 120% (base/acid stoichiometry excess), or between 60 and 100%.

The neutralized carboxylated prepolymer is then dispersed under high shear in water so as to obtain dispersions with dry matter contents of between 20 and 70%, preferably between 30 and 60% by mass.

In some embodiments, the emulsification in water is carried out before the neutralization with a base. However, it is preferred that the emulsification in water be carried out after the neutralization with a base. Step (iii) consists in reacting the isocyanate groups of the prepolymer with a reagent comprising several active hydrogen functions, called a chain extender, for example with a polyamine comprising at least two -NH2 functions or a polyol comprising at least two -OH functions. A polyurethane-urea with carboxylate groups neutralized by a base is thus obtained.

Examples of polyamine chain extenders are ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, dipropylenetriamine, hexamethylenediamine, isophoronediamine, piperazine, xylylenediamine, tris(2-aminoethyl)amine, hydrazine or polyoxypropyleneamines (e.g. marketed under the name Jeffamine® from Huntsman).

Examples of polyhydroxylated chain extenders are linear or branched polyols selected for example from the group consisting of ethylene glycol, propylene glycol, 1,2- and 1,3-propanediol, 1,2-, 1,3-, and 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, glycerol, neopentyl glycol, trimethylol propane, pentaerythritol, cyclohexane-dimethanol, 1,2- and 1,4-cyclohexanediol, 1,8-octanediol, diethylene glycol, triethylene glycol, dipropylene glycol, tripropylene glycol or polyether glycol polyols such as polypropylene glycol or polyethylene glycol.

The chain extenders are generally added in an amount such that the proportion of NH2 and/or OH functions corresponds to an extension of 30% to 120%, or even 40 to 90%, of the residual isocyanate functions of the polyurethane prepolymer, in other words the ratio of the number of OH+NH2 functions to the number of isocyanate functions initially present is between 0.3 and 1.2, preferably between 0.4 and 0.9.

Optionally, the anionic polyurethane comprising COO M ⁺ groups may further comprise alkoxysilyl groups. These alkoxysilyl groups may be introduced by reaction of an epoxysilane with a portion of the carboxylate groups of said anionic polyurethane or anionic (styrene)acrylic polymer.

The epoxysilane is preferably selected from the group consisting of 3-glycidyloxypropyl-trialkoxysilanes, 3-glycidyloxypropyldialkoxyalkylsilanes, epoxycyclohexyl-ethyltrialkoxysilanes, epoxycyclohexylethyldialkoxyalkylsilanes, and water-soluble epoxysilane oligomers. These oligomers comprise a short siloxane chain carrying epoxy side groups and are described for example in EP1896522. They are available on the market for example under the reference CoatOSil MP200 (Momentive).

The functionalization of an anionic polyurethane with an epoxysilane has notably been described in international applications WO2021/074134 and WO2022/219264.

The polyurethane, when it is an ionic polyurethane, preferably has a surface charge density, determined at pH 7.0 by means of a flow current detector (SCD), preferably between 100 and 400 pmoles/g, in particular between 150 and 350 pmoles/g.

In another particular embodiment, the process for preparing the polyurethane is carried out in a polar solvent such as acetone, methyl ethyl ketone, or tetrahydrofuran. In such an embodiment, an isocyanate prepolymer is formed by:

- mixture of one or more polyols and one or more hydroxylated or amino carboxylic acids with a stoichiometric excess of one or more diisocyanates, in said polar solvent, in the presence of a chain extension agent and a base,

- addition of water until a continuous aqueous phase is formed, and

- evaporation of the polar solvent.

In the composition according to the invention, the weight ratio between the content of polyurethane-based resin particles and the content of poly(vinyl acetal)-based resin particles is preferably between 0.05 and 20, for example between 0.1 and 10, in particular between 0.1 and 5, preferably between 0.1 and 2, or even between 0.2 and 0.8.

The weight ratio between the content of polyurethane resin particles and the content of poly(vinyl acetal) resin particles may, for example, be between 0.2 and 5.

The weight ratio between the content of polyurethane-based resin particles and the content of poly(vinyl acetal)-based resin particles may in particular be between 0.15 and 5, between 0.2 and 5, between 0.2 and 4, between 0.2 and 3, or between 0.2 and 2.

The poly(vinyl acetal) resin particles and the polyurethane resin particles preferably have a size volume distribution such that d50 is between 50 and 500 nm, in particular between 80 and 300 nm, or even between 100 and 250 nm. The particle size distribution is determined in particular by dynamic light diffraction.

Preferably, the composition according to the invention does not comprise any other resin particles than those based on polyurethane and those based on poly(vinyl acetal). Preferably, the total content of polyurethane-based resin particles and poly(vinyl acetal)-based resin particles is from 5 to 50% by weight (for example, from 7 to 48%, in particular from 10 to 45%, or even from 15 to 40%, or even from 20 to 35%).

The plasticizer(s) is (are) advantageously chosen from polyethylene glycol esters, adipates, sebacates, phthalates, benzoate esters and mixtures of two or more of these compounds. Examples include tri(ethylene glycol) di(2-ethylhexanoate), tri(ethylene glycol) di(2-ethylbutyrate), tri(ethylene glycol) di(n-heptanoate), tetra(ethylene glycol) di(n-heptanoate), bis(2-butoxyethyl) adipate, dibutyl sebacate, dibutyl phthalate or dioctyl phthalate.

Preferably, the plasticizer content is between 5% and 30% by weight, more preferably between 10% and 25% by weight, relative to the total dry weight of resin.

The emulsifier(s) is (are) advantageously chosen from ionic emulsifiers (cationic or anionic) and non-ionic emulsifiers. Anionic emulsifiers are in particular carboxylates or sulfonates. Carboxylates are for example salts of saturated or unsaturated fatty acids such as stearates, oleates and laurates, rosin salts such as for example potassium oleate. Sulfonates are for example alkyl sulfonates, aryl sulfonates, alkyl aryl sulfonates or sulfonated esters such as for example sodium dodecyl sulfate. Non-ionic emulsifiers are in particular polyoxyethylene alkylphenyl ethers.

The emulsifier(s) is (are) preferably anionic. Such emulsifiers in fact make it possible to obtain a lower water uptake than non-ionic emulsifiers.

Preferably, the total weight content of emulsifier(s) is between 0.1% and 10%, for example between 2% and 6% or between 4 and 8%. The glass transition temperature of the poly(vinyl acetal) resin particles is preferably between 5 and 40°C, in particular between 10 and 30°C.

Polyurethane resin particles generally have two glass transition temperatures. However, it may happen that only one of these glass transition temperatures is experimentally determinable. The glass transition temperature(s) of the polyurethane resin particles is (are) preferably between -80°C and 100°C.

The glass transition temperature is notably measured by differential scanning calorimetry.

The minimum film forming temperature (generally referred to by its acronym “MFFT”) of the composition is preferably less than 30°C, in particular less than 20°C, or even less than 10°C and even less than 0°C, in order to allow film formation and coalescence of the coating at room temperature in different climatic conditions. The minimum film forming temperature can be modified in particular by varying the amount of plasticizer, or even by adding coalescing agents. The MFFT is determined according to the standards ASTM D 2354 and ISO 2115.

In some embodiments, the composition further comprises one or more fillers.

The fillers are advantageously of mineral nature. The fillers are preferably chosen from calcium carbonate, calcium stearate, clays, talc, dolomite, mica, silica sands, ground basalt, barium sulfate, kaolin, and mixtures of two or more of these compounds. The fillers preferably have a particle size ranging from 0.5 to 500 pm, in particular from 1 to 200 pm, measured by laser granulometry.

The total weight content of fillers is preferably between 5 and 80%, for example between 6 and 70%, in particular between 7 and 65%, or between 8 and 50%, or between 9 and 40% or between 10 and 25%, or between 11 and 24%.

In some embodiments, the composition further comprises one or more pigments. The pigments are preferably selected from inorganic pigments (e.g. titanium dioxide or iron oxide), organic pigments (e.g. carbon black), and mixtures of two or more of these compounds.

The total weight content of pigments is preferably between 0.1 and 20%, in particular between 2 and 10%.

In a particular embodiment, the composition further comprises one or more crosslinking agents.

The crosslinking agent(s) is (are) advantageously chosen from water-soluble organometallic compounds, water-insoluble metal oxide or hydroxide particles, and organic compounds reactive with hydroxyl groups.

Organic compounds reactive with hydroxyl groups are in particular polyfunctional molecules reactive with hydroxyl groups, such as for example poly(carboxylic acids), polyisocyanates or polyaldehydes. We can notably cite glutaraldehyde or citric acid.

The water-soluble organometallic compounds are preferably complexes of zirconium, titanium, zinc or boron. Examples of water-soluble organometallic compounds are ammonium bis(carbonato-) dihydroxyzirconate, ammonium bis(lactato-) dihydroxytitanate, titanium lactate or titanium triethanolaminate.

The water-insoluble metal oxide or hydroxide particles are in particular oxides or hydroxides of zinc, zirconium or aluminium (preferably zinc oxides). These particles can have a size of between 0.5 and 100 pm, in particular between 1 and 50 pm. The particle size is typically determined by laser particle size analysis.

The total weight content of crosslinking agent(s) is preferably between 0.01% and 10%, for example between 0.1% and 5%, or even between 0.5% and 2%.

The crosslinking agent allows several resin particles to be crosslinked at the time of film formation. This results in slightly faster drying and, above all, lower water absorption, especially after immersion in water. The amount of water in the composition is preferably between 10 and 70% by weight, in particular between 20 and 60% by weight, for example between 30 and 50% relative to the total weight of the composition.

In a particular embodiment, the composition further comprises one or more additives, notably chosen from:

- defoaming agents (e.g. silicone, fluorosilicone, mineral oil, acrylic, vinyl polymers),

- coalescing agents (e.g. glycols such as propylene glycol or diethylene glycol, glycol ethers such as dipropylene glycol n-butyl ether or propylene glycol methyl ether acetate, alcohol esters such as 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate, pyrrolidone such as N-methyl-2-pyrrolidone or N-butyl-2-pyrrolidone),

- rheological agents (for example polyurethane/polyurea, polyacrylic, polyamide, castor oil-based, or clay or cellulose ether-based),

- dispersing agents (e.g. silicone, polyacrylate, polyether type),

- adhesion promoting agents (e.g. silanes),

- bactericidal or algicidal agents (in particular of the isothiazolinone type such as benzisothiazolinone or methylisothiazolinone, or of the halogenated type).

The total weight content of these additives is preferably between 0.1 and 10%, preferably between 0.2 and 5% relative to the total weight of the composition.

Dispersing agents are useful to help disperse fillers and pigments. As previously noted, coalescing agents allow the minimum film formation temperature to be adjusted if necessary.

The composition according to the invention is normally a single-component composition, that is to say that it does not require the addition of another composition before or after application.

The composition according to the invention can be used for sealing different substrates (in particular, for waterproofing). A waterproofing coating (or waterproofing membrane) can typically be formed by applying said composition to a substrate and drying it. Thus, the present invention relates to a waterproofing coating, obtained by application and drying of said composition. It further relates to the use of such a waterproofing coating as a water-proofing coating. The water-proofing may be a waterproofing against liquid water and/or water vapour. In a particular embodiment, the coating is used for waterproofing against chlorinated water. By "chlorinated water" is meant water comprising chlorine, typically in a content of between 0.2 and 5 mg/L, in particular between 1 and 3 mg/L.

Application to the substrate is done using a roller, brush or spray. It can be done in several layers (for example, two layers).

Depending on the type of substrate, drying can be done in the air, naturally, therefore without heating or blowing, in a period typically ranging from a few minutes to a few hours, or possibly by heating for a few seconds or a few minutes at a moderate temperature (e.g. between 50°C and 130°C, in particular between 70°C and 120°C).

The final (dry) coating may result from the application of several successive layers. Its dry thickness is preferably between 0.1 and 2.0 mm, in particular between 0.2 and 1.5 mm.

The substrate is preferably made of cementitious material (for example concrete, mortar or coating), but it can also be made of stone (in particular limestone), brick, terracotta, sandstone, ceramic, wood, paper, textile, plastic, plaster or even bitumen. In a particular embodiment, the substrate is made of cementitious material, and is covered with a layer of primer such as an epoxy primer.

The substrate may in particular be a roofing substrate such as a tile or a membrane (in particular, a membrane based on thermoplastic polyolefin (TPO), based on ethylene-propylene-diene terpolymer (EPDM), or based on polyvinyl chloride (PVC)), a balcony substrate, a terrace substrate, a wet room substrate, or even a facade substrate. In a preferred embodiment, the substrate is a swimming pool substrate.

Another object of the present invention is a method of waterproofing a roof, a terrace, a balcony, a wet room, a facade, or a swimming pool comprising the application, on a substrate of said roof, terrace, balcony, wet room, facade, or swimming pool, of a composition as defined in the present application, to form a coating, then drying said coating to obtain a dry coating preferably having a thickness ranging from 0.1 to 2 mm.

The following examples illustrate the invention in a non-limiting manner.

EXAMPLES

Synthesis of an aromatic polyurethane dispersion (PUD1)

42.9 g of bis-MPA (2,2-Bis(hydroxymethyl)propionic acid, Perstorp) were dissolved in 105 g of N-methyl-2-pyrrolidone (NMP) at 70 °C. Then, 238 g of Acclaim 1111 BD (polyether polyol, functionality 2, Covestro) were added. The mixture was then cooled to 50 °C and 223 g of Desmodur T80 (2,4- and 2,6-toluene diisocyanate, Covestro) were added rapidly under stirring (300 rpm) and stirring was maintained for 4 hours. NCO titration: 109 mg KOH/g.

At 40°C, 30.0 g of triethylamine was added and after 15 minutes, 1000 g of water was added rapidly under vigorous stirring (1000 rpm) followed by 13.5 g of ethylenediamine. The system was mixed at 300 rpm for an additional 1 hour at 30°C.

A stable aromatic polyurethane (PUD) dispersion was obtained, with a solids content of 44%, a particle size of 135 nm, and glass transition temperatures of -75°C and 70°C (DSC, 20°C/min).

Synthesis of an aliphatic polyurethane dispersion (PUD2)

An aliphatic polyurethane dispersion was prepared according to the same protocol as above, in the same molar proportions, replacing the Acclaim 1111 BD polyol with the polyol P-1010 (polyester polyol, functionality 2, Kuraray) and the Desmodur T80 diisocyanate with Desmodur I (Covestro, isophorone diisocyanate). NCO titration: 117 mg KOH/g (before addition of amines).

-> A stable aliphatic polyurethane (PUD) dispersion was obtained, with a dry extract of 45%, a particle size of 165 nm, and a glass transition temperature of -61°C (DSC, 20°C/min). Preparation of compositions comprising a PUD resin and a PVB resin

Compositions comprising a PUD resin (i.e. PUD1 or PUD2), and a PVB resin, in different ratios, were prepared, one with the PUD1 dispersion and the other with the PUD2 dispersion. The PVB dispersion has a solids content of 45%, a particle size of 180 nm, and a glass transition temperature of 24°C.

The weight contents (relative to the total weight of the composition) are indicated in Table 1 below.

[Tables 1]

*Comparative compositions

Performance of coatings formed from compositions comprising a PUD resin and a PVB resin The coatings were applied using a film puller on a concrete or polyethylene substrate with a typical thickness of 1 mm wet. The resulting films were dried at 23°C and 50% relative humidity for 7 days. a) Mechanical properties and tear resistance are measured according to ASTM D412.

Viscosity is measured with a Brookfield using a So5 spindle at 23°C.

Shore A hardness according to ASTM D2240.

Adhesion was measured according to ASTM D 930. The films were applied to concrete with and without epoxy primer. For films immersed in water, adhesion was evaluated after 20 days of immersion at 23°C.

Water absorption: The films applied and dried for 7 days on polyethylene were immersed in water for 28 days. After 28 days, the m _swollen weight of the films was measured (the film surfaces were dried with a paper towel). The films were then dried in an oven for 18 h at 50 °C and were then weighed to give m _s ec. The water absorption of the film is calculated with the formula: ■ i / zr. / \ ^swollen ^sec

Water absorption (%) = - . 100

^sec

The mass loss is calculated from the initial weight of the film mmitiai:

Mass loss . 100

QUV aging was performed according to ASTM G154 (cycle 7: UV, temperature, condensation and water spray) for 2600h and the mechanical properties were then tested according to ASTM D2240.

[Tables 2]

Comparative compositions

**rating from 1 to 5: 1 being the worst rating and 5 being the best

The results in Table 2 demonstrate a good compatibility between aromatic polyurethane and PVB. Indeed, no gelation phenomenon occurred in the liquid state and no decrease in mechanical properties was observed for the films. The compatibility of the two resins is also demonstrated by the yellowing results, as well as by the maintenance (or possibly slight decreases) of mechanical performances.

The results also highlight a synergy between the two resins, particularly for adhesion (with and without primer, with or without immersion in water) with a ratio

PUD/PVB between 40/60 and 20/80. It should be noted in particular that the PUD/PVB 30/70 and 20/80 systems show improved adhesion while retaining the high tensile strength of pure PVB and the low water absorption of pure PUD. Tensile tests after 2600 hours of UV exposure also demonstrate the improved UV resistance of the compositions according to the invention.

[Tables 3]

Comparative compositions

**rating from 1 to 5: 1 being the worst rating and 5 being the best

The results in Table 3 demonstrate a good compatibility between aliphatic polyurethane and PVB. Indeed, no decrease in mechanical properties was observed for the films. The compatibility of the two resins is also demonstrated by the yellowing results, as well as by the maintenance (or possibly slight decreases) of mechanical performances.

The results also highlight a synergy between the two resins, particularly for adhesion. It should be noted in particular that the PUD/PVB 30/70 and 20/80 systems show improved adhesion while retaining the high tensile strength of pure PVB and the low water absorption of pure PUD. Finally, an improvement in UV resistance was observed for the compositions according to the invention, which comprise both resins. b) A composition was applied to the concrete substrate of a swimming pool, on which an epoxy primer had been previously deposited. After 1 week of drying outdoors at a temperature varying between 15 and 25°C and a relative humidity between 30 and 70%, the swimming pool was filled with chlorinated water with a chlorine concentration of 1-2 ppm (provided via sodium hypochlorite) and a pH = 7.2 (adjusted with sulfuric acid). The pH and chlorine concentration were kept constant for 12 months and the appearance of the coating was qualitatively characterized in terms of chalking and wet adhesion (rating from 1 to 5: 1 being the worst and 5 being the best). The results are shown in Table 4 below.

*Compositions comparatives [Tables 4]

*Comparative compositions

As can be seen in Table 4, the compositions according to the invention comprising the PUD resin and the PVB resin have both high chemical resistance, in particular to chlorinated water, and strong adhesion in the wet state.

Claims

1. A sealing composition, which is an aqueous dispersion comprising: water, poly(vinyl acetal)-based resin particles, polyurethane-based resin particles, one or more plasticizers, and one or more emulsifiers, wherein the total content of resin particles is 5 to 50% by weight. 2. Composition according to claim 1, in which the poly(vinyl acetal) based resin is based on poly(vinyl butyral). 3. Composition according to claim 2, in which the poly(vinyl butyral)-based resin comprises residual alcohol and acetate functions. 4. Composition according to any one of claims 1 to 3, further comprising one or more fillers, the filler content preferably being between 5 and 80% by weight, relative to the total weight of the composition. 5. Composition according to claim 4, in which the fillers are chosen from calcium carbonate, calcium stearate, clays, talc, dolomite, mica, silica sands, ground basalt, barium sulfate, kaolin, and mixtures of two or more of these compounds. 6. Composition according to any one of claims 1 to 5, further comprising from 0.1 to 20% by weight of pigments, relative to the total weight of the composition. 7. Composition according to any one of claims 1 to 6, in which the total weight content of emulsifier(s) is between 0.1% and 10%. 8. Composition according to any one of claims 1 to 7, in which the plasticizer content is between 5% and 30% by weight, preferably between 10% and 25% by weight, relative to the total dry weight of resin. 9. Composition according to any one of claims 1 to 8, in which the amount of water is between 10 and 70% by weight, in particular between 20 and 60% by weight, relative to the total weight of the composition. 10. A composition according to any one of claims 1 to 9, wherein the weight ratio between the content of polyurethane-based resin particles and the content of poly(vinyl acetal)-based resin particles is between 0.05 and 20, for example: between 0.15 and 5, between 0.2 and 5, between 0.2 and 4, between 0.2 and 3, between 0.2 and 2, between 0.1 and 2, or between 0.2 and 0.8. 11. A composition according to any one of claims 1 to 10, wherein said polyurethane is an anionic polyurethane comprising pendant carboxylate groups COO M ⁺ where M ⁺ is a cation resulting from the neutralization of the carboxylic groups by a base. 12. Waterproofing coating, obtained by applying and drying a composition as defined in any one of claims 1 to 11. 13. Use of a sealing coating as defined in claim 12, as a sealing coating against water, in particular against chlorinated water. 14. A method of waterproofing a roof, terrace, balcony, damp room, facade, or swimming pool comprising the application, on a substrate of said roof, terrace, balcony, damp room, facade, or swimming pool, of a composition according to any one of claims 1 to 11 to form a coating, then drying said coating to obtain a dry coating preferably having a thickness ranging from 0.1 to 2 mm.