Sealing composition

Abstract

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

Description

Waterproofing composition

[0001] The present invention relates to a composition for waterproofing various substrates such as paper or cementitious material substrates. It also relates to a waterproofing coating, in particular a watertight coating, formed from such a composition. It further relates to a method for waterproofing a roof, a terrace, a balcony, a damp room or a facade, via the formation of such a coating.

[0002] Many compositions have been developed to make various substrates waterproof. For example, in the construction industry, to waterproof roofs, terraces, balconies, wet rooms or facades, bituminous or synthetic membranes are used, assembled by welding, hot-poured asphalt coatings, or systems known in the art as "liquid waterproofing systems" (LWS). The latter consist of polymer resin-based materials applied in one or more layers by spraying or by application with a roller, brush or squeegee. Different types of resins are used, in particular polyesters, acrylics, neoprene bitumens, or polyurethane resins. Highly durable and easy to apply, these systems generally allow pedestrian traffic directly after drying, eliminating the need for heavy protection.However, the mechanical performance, water resistance and durability of these systems still need to be improved.

[0003] Another application related to the construction field concerns the sealing of paper bags used for packaging plaster or cement-based powders. Paper bags require protection against the penetration of atmospheric water vapor through the layers of the bag, in order to avoid degradation of the packaged powders. The waterproof bags known for this application are notably made of polyethylene sheets inserted between the two paper plies of the bag, which however make the paper bag non-recyclable. To make paper bags recyclable and waterproof against water vapor, one strategy is to replace the current bags with a recyclable two-ply bag without plastic-based sheet, in which one of the plies would have a coating based on a very thin polymer, to ensure good water barrier properties.

[0004] Films based on bio-sourced, more environmentally friendly polyesters have been developed. However, these require a heating step at a temperature above the polymer's melting point, which is generally too high for paper.

[0005] The invention therefore aims to propose a composition which makes it possible to form a waterproof coating (or membrane):

[0006] - compatible with different substrates, in particular cementitious materials and paper,

[0007] - can be dried quickly at room temperature,

[0008] - offering very good barrier properties to liquid or vapor water,

[0009] - presenting improved performances, notably in terms of mechanical properties, water resistance and durability.

[0010] Another aim of the invention is to provide a waterproofing coating (or membrane) which has a reduced carbon footprint.

[0011] Thus, the present invention relates to a sealing composition, which is an aqueous dispersion, comprising: water, particles of a poly(vinyl acetal)-based resin, particles of a resin other than a poly(vinyl acetal)-based resin, one or more plasticizers, and one or more emulsifiers, wherein the total content of resin particles is 5 to 50% by weight.

[0012] In some embodiments, the poly(vinyl acetal)-based resin is poly(vinyl butyral)-based.

[0013] In some embodiments, the poly(vinyl butyral)-based resin comprises residual alcohol and acetate functionalities.

[0014] In some embodiments, the poly(vinyl butyral)-based resin is derived from the recycling of laminated glazing.

[0015] In certain embodiments, the composition further comprises one or more crosslinking agents, preferably chosen from silanes, preferably from alkoxysilanes optionally comprising a functional group reactive with respect to carboxylic acid, carboxylate or hydroxy functions, such as an epoxy or amine group.

[0016] In some embodiments, the weight ratio of crosslinking agent content to poly(vinyl acetal) resin content is between 0.001 and 0.10, especially between 0.002 and 0.06.

[0017] In some embodiments, the composition 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. The fillers may be selected from calcium carbonate, clays, talc, dolomite, mica, silica sands, ground basalt, barium sulfate, kaolin and mixtures of two or more of these compounds.

[0018] In some embodiments, said resin other than a poly(vinyl acetal) based resin is selected from styrene-acrylic resins, styrene-butadiene resins, acrylic resins, alkyd resins, and a mixture of two or more of these resins, preferably from alkyd resins.

[0019] In some embodiments, the composition further comprises from 0.1 to 20% by weight of pigments, relative to the total weight of the composition.

[0020] In some embodiments, the total weight content of emulsifier(s) is between 0.1% and 10%.

[0021] In some embodiments, the weight ratio of plasticizer content to poly(vinyl acetal) resin content is between 0.1 and 1, especially between 0.2 and 0.5.

[0022] 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.

[0023] In some embodiments, the weight ratio of the content of particles of resin other than a poly(vinyl acetal)-based resin to the content of particles of a poly(vinyl acetal)-based resin is between 0.05 and 20, preferably between 0.1 and 10, or even between 1.0 and 3.0.

[0024] The present invention also relates to a waterproof coating, obtained by applying and drying a composition as defined in the present application.

[0025] It further relates to the use of a waterproofing coating as defined in the present application, as a waterproofing coating.

[0026] Another subject of the present invention is a method for waterproofing a roof, a terrace, a balcony, a wet room or a facade comprising the application, on a substrate of said roof, terrace, balcony, wet room or facade, of a composition according to the invention, to form a coating, then drying said coating to obtain a dry coating preferably having a thickness ranging from 0.1 to 2.0 mm. Said substrate is preferably made of cementitious material. DETAILED DESCRIPTION

[0027] The sealing composition according to the invention is an aqueous dispersion which comprises water, particles of a poly(vinyl acetal)-based resin, particles of a resin other than a poly(vinyl acetal)-based resin, one or more plasticizers, and one or more emulsifiers, wherein the total content of resin particles is 5 to 50% by weight (for example, 7 to 48%, especially 10 to 45%, or even 15 to 40%, or even 20 to 35%).

[0028] Preferably, the poly(vinyl acetal) based resin is poly(vinyl butyral) based, also called PVB.

[0029] Preferably, the poly(vinyl acetal)-based resin, in particular poly(vinyl butyral)-based resin, consists of poly(vinyl acetal), in particular poly(vinyl butyral).

[0030] 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 carried out 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.

[0031] The polyvinyl butyral-based resin is advantageously derived from recycled laminated glazing. These glazings use PVB as a lamination interlayer between two sheets of glass. Using recycled materials reduces the carbon footprint of the sealing system.

[0032] 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 different constituents of the composition are given by weight, relative to the total weight of the composition.

[0033] The composition (or "aqueous dispersion") further comprises particles of a resin other than a poly(vinyl acetal)-based resin. This resin may in particular be chosen from styrene-acrylic resins (in particular carboxylated styrene-acrylic resins), styrene-butadiene resins, acrylic resins, alkyd resins, and a mixture of two or more of these resins.

[0034] In a preferred embodiment, the particles of a resin other than a poly(vinyl acetal) based resin are particles of styrene-acrylic resin (especially carboxylated styrene-acrylics) or alkyd resin, more preferably alkyd resin.

[0035] The weight ratio between the content of particles of resin(s) other than poly(vinyl acetal) and the content of particles of resin based on poly(vinyl acetal) is preferably between 0.05 and 20, for example between 0.1 and 10, in particular between 1.0 and 5.0, or even between 1.0 and 3.0. In a particular embodiment, this weight ratio is between 0.4 and 2.0.

[0036] The poly(vinyl acetal) resin particles and the particles of the other resin preferably have a volume size distribution such that the d50 is between 50 and 300 nm, in particular between 100 and 250 nm. The particle size distribution is determined in particular by dynamic light diffraction.

[0037] In a particular embodiment, said resin other than a poly(vinyl acetal)-based resin is bio-sourced. The bio-sourced nature of the latter contributes to reducing the carbon footprint of the composition.

[0038] When the resin other than poly(vinyl acetal) resin is an alkyd resin, it is advantageous to use a drier, particularly organic salts of cobalt, lead or zinc oxides (preferably an organic salt of cobalt).

[0039] 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.

[0040] Preferably, the weight ratio between the plasticizer content and the poly(vinyl acetal)-based resin content is between 0.1 and 1, in particular between 0.2 and 0.5.

[0041] 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.

[0042] The emulsifier(s) is (are) preferably anionic. Such emulsifiers allow for lower water uptake than non-ionic emulsifiers.

[0043] 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%.

[0044] The glass transition temperature of the aqueous composition is preferably between 5 and 40°C, in particular between 10 and 30°C, in order to maintain good flexibility after drying. The glass transition temperature is measured in particular by differential scanning calorimetry. The glass transition temperature can be modified in particular by varying the quantity of plasticizer.

[0045] 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 quantity of plasticizer, or even by adding coalescing agents. The MFFT is determined according to ASTM D 2354 and ISO 2115 standards.

[0046] In some embodiments, the composition further comprises one or more fillers.

[0047] The fillers are advantageously of a 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 µm, in particular from 1 to 200 µm, measured by laser granulometry.

[0048] 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 even between 8 and 50%, or between 9 and 40% or between 10 and 25%, or even between 11 and 24%.

[0049] In some embodiments, the composition further comprises one or more pigments.

[0050] 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.

[0051] The total weight content of pigments is preferably between 0.1 and 20%, in particular between 2 and 10%.

[0052] Preferably, the composition further comprises one or more crosslinking agents.

[0053] The crosslinking agent(s) is (are) advantageously chosen from water-soluble organometallic compounds, water-insoluble metal oxide or hydroxide particles, organic compounds reactive with hydroxyl groups, and silane compounds.

[0054] 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. Examples include glutaraldehyde or citric acid.

[0055] 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.

[0056] The water-insoluble metal oxide or hydroxide particles include zinc, zirconium, or aluminum oxides or hydroxides (preferably zinc oxides). These particles may have a size between 0.5 and 100 µm, especially between 1 and 50 µm. The particle size is typically determined by laser particle size analysis.

[0057] In a particular embodiment, the crosslinking agent is a silane, preferably an alkoxysilane. More preferably, the crosslinking agent is an alkoxysilane comprising a functional group reactive with respect to carboxylic acid, carboxylate or hydroxy functions, such as an epoxy group (i.e. an epoxy-alkoxysilane) or amine group (i.e. amino-alkoxysilane). The total weight content of crosslinking agent(s) is preferably between 0.01% and 10%, for example between 0.5% and 2%.

[0058] The crosslinking agent allows several resin particles to be crosslinked. This results in slightly faster drying and, above all, lower water absorption, especially after immersion in water.

[0059] 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.

[0060] In a particular embodiment, the composition further comprises one or more additives, notably chosen from:

[0061] - defoaming agents (for example silicone, fluoro-silicone, mineral oil, acrylic, vinyl polymers),

[0062] - 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),

[0063] - rheological agents (for example polyurethane / polyurea, polyacrylic, polyamide, castor oil-based, or even clay-based or cellulose ether-based),

[0064] - dispersing agents (for example silicone, polyacrylate, polyether type),

[0065] - bactericidal or algicidal agents (in particular of the isothiazolinone type such as benzisothiazolinone or methylisothiazolinone, or of the halogenated type).

[0066] 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.

[0067] Dispersing agents are useful to help disperse fillers and pigments. As previously mentioned, coalescing agents allow the minimum film formation temperature to be adjusted if necessary.

[0068] Advantageously, the composition comprises less than 1% by weight (or even less than 0.2% by weight) of castor oil, relative to the total weight of the composition. Even better, the composition does not comprise castor oil.

[0069] 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.

[0070] The composition according to the invention can be used for waterproofing 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 applying and drying said composition. It further relates to the use of such a waterproofing coating as a waterproofing coating. The waterproofing can be a waterproofing against liquid water and / or water vapor.

[0071] Application to the substrate is done using a roller, brush or spray. It can be done in several layers (for example, two layers).

[0072] 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 minutes at a moderate temperature (e.g. between 50°C and 130°C, particularly between 70°C and 120°C).

[0073] The substrate is preferably made of cementitious material (for example concrete, mortar or plaster), but it can also be made of stone (particularly limestone), brick, terracotta, sandstone or even ceramic.

[0074] Such substrates may in particular be roof, terrace, balcony, wet room or facade substrates. Thus, the present invention also relates to a method for waterproofing a roof, a terrace, a balcony, a wet room or a facade comprising the application, on a substrate of said roof, terrace, balcony, wet room or facade, of a composition according to the invention, to form a coating, then drying said coating to obtain a dry coating.

[0075] The thickness of the dry coating is preferably 0.1 to 2.0 mm, especially 0.2 to 1.5 mm.

[0076] The substrate can alternatively be a layer of paper (e.g. white paper, coated paper, friction paper, textured paper, kraft paper, such as white, unbleached or brown kraft paper). The weight of a layer of paper can be between 40 and 300 g / m 2 , for example between 50 and 150 g / m 2The weight of the dry coating is preferably between 2 and 40 g / m 2 , especially between 5 and 25 g / m 2 , for example between 8 and 25 g / m 2 , or even between 9 and 20 g / m 2 , or even between 10 and 18 g / m 2 .

[0077] The composition according to the invention can in particular be applied and dried on a layer of paper intended to form a bag. Generally, the paper bag comprises two superimposed layers of paper each having two faces, i.e. an inner face and an outer face, each of the two inner faces facing each other, and the coating is formed on one of the two facing faces. Such sealed bags can then be used for packaging materials in powder form, such as cement- or plaster-based powders.

[0078] The following examples illustrate the invention in a non-limiting manner. EXAMPLES

[0079] Abbreviations

[0080] MVTR: Moisture Vapor Transmission Rate

[0081] HR: Relative Humidity

[0082] Example 1: Waterproofing paper

[0083] The PVB-based aqueous dispersion includes PVB, triethylene glycol-bis(2-ethylhexanoate) as a plasticizer and potassium oleate as an emulsifier. The solids content is 50%.

[0084] The carboxylated styrene-acrylic polymer emulsion is bio-sourced and has a solids content of 50%.

[0085] The alkyd resin emulsion has a solids content of 50%.

[0086] The dispersions of PVB and the second resin (i.e. acrylic or alkyd styrene) are mixed at room temperature, possibly in the presence of 2% by weight of an epoxysilane. When the second resin is an alkyd resin, a cobalt-based drier was used. A film a few tens of micrometers thick (the thickness of the film before drying is adjusted to obtain the desired dry coating weight) is then deposited on a sheet of white kraft paper and dried at room temperature or for 2 min at 80°C. The coatings can also be applied in two stages, a first application with drying at room temperature or 80°C, followed by a second application with drying at room temperature or 80°C. The water vapor permeability properties under temperate (23°C, 50%RH) and tropical (38°C, 90%RH) conditions are then measured.

[0087] In comparison, the mixture of PVB and styrene-acrylic dispersions in functionalization by a silane compound is deposited with a thickness similar to the previous embodiment and dried at room temperature.

[0088] MVTR (g / m² / day) White paper Weight (g / m 2 )50% HR - 23°C90% HR - 38°CNo deposit / ≈400≈2000PVB resin62181519PVB resin (b,c) 62241527Styrene-acrylic resin / PVB 90 / 10114663Styrene-acrylic resin / PVB 85 / 1517,54695Styrene-acrylic resin / PVB 70 / 301184120Styrene-acrylic resin / PVB 70 / 3020 (2 * 10)43107Alkyd resin / PVB 70 / 30 (a) 1073742Alkyd resin / PVB 70 / 30 (a,c) 1260604Styrene-acrylic resin / PVB 90 / 10 (b,c) 16.5 (2 x 8.5)725Styrene-acrylic resin / PVB 85 / 15 (b,c) 21 (2*10.5)1344

[0089] a) siccative used: cobalt salt; b) presence of a silane-type crosslinking agent; c) heating for 2 min at 80°C

[0090] Table 1 above shows that the combination of PVB particles with particles of a second resin, such as a styrene-acrylic or alkyd resin, provides better sealing of the paper layer, whether in temperate or tropical conditions, particularly compared to PVB particles alone. A brief heating step of the sealing layer in the presence of a crosslinking agent, particularly of the silane type, further improves its performance.

[0091] Example 2: Waterproofing a cementitious substrate

[0092] Example 2 concerns the implementation of a coating (or “membrane”) under tiles for waterproofing damp rooms.

[0093] The PVB-based aqueous dispersion comprises PVB, triethylene glycol-bis(2-ethylhexanoate) as a plasticizer and potassium oleate as an emulsifier. The solids content is 50%.

[0094] The emulsion of the carboxylated styrene-acrylic polymer has a solids content of 50%.

[0095] The two dispersions were mixed, and to the resulting mixture were added water, fillers (filler 1: calcium carbonate, filler 2: kaolin, filler 3: barium sulfate), pigments (titanium dioxide), defoaming agents, a polyacrylic dispersing agent, a polyurethane rheological agent, and a coalescing agent (propylene glycol). The two compositions tested are described below in Table 2 (denoted "Compositions 1 and 2"). As a comparative example, a composition comprising only one resin (PVB) was prepared ("Comparative" in Table 2).

[0096] In Table 2, the contents are expressed as mass percentages, relative to the total weight of the composition.

[0097] Comparison12Water added6.306.306.3Thickener0.400.400.6PVB dispersion44.1523.15 (9.3) a 32 (12.8) a Styrene-acrylic dispersion0.0021.00 (10.5) b 12 (6) b Biocide0,200,200.2Defoamer0,500,500.2Dispersant0,050,050.2Pigment1,001,006Charge118,4018,4014.5Charge 21,001,001Charge 328,0028,0028

[0098] a) weight content of PVB resin, relative to the total weight of the composition,

[0099] b) weight content of styrene-acrylic resin, relative to the total weight of the composition

[0100] Coatings of 0.3 to 0.4 mm dry thickness were then obtained after application of a 1 mm wet film thickness and drying for 7 days at 23°C and 50% relative humidity.

[0101] Table 3 below indicates for each of the examples, the tensile strength (in MPa) and the elongation at break (in %) (determined using a tensile bench at a speed of 50 mm / min at 23°C) and the adhesion of a cementitious tile adhesive deposited on the membrane determined using an instrument for measuring the adhesion force (speed 0.2 mm / s).

[0102] Comparison12Tension 23°C (MPa)3.12.73.8Tile adhesive adhesion (MPa)01.10.8

[0103] It can be deduced from these different results that the coatings obtained from compositions 1 and 2 containing a mixture of two resins, i.e. PVB and styrene-acrylic, exhibit better adhesion of the tile adhesive than the comparative membrane containing 100% PVB. The tensile strength properties remain similar.

Claims

A sealing composition, which is an aqueous dispersion comprising: water, particles of a poly(vinyl acetal)-based resin, particles of a resin other than a poly(vinyl acetal)-based resin, one or more plasticizers, and one or more emulsifiers, wherein the total content of resin particles is 5 to 50% by weight. The composition of claim 1, wherein the poly(vinyl acetal) based resin is poly(vinyl butyral) based. Composition according to claim 2, in which the poly(vinyl butyral) based resin comprises residual alcohol and acetate functions. Composition according to claim 2 or 3, in which the poly(vinyl butyral)-based resin comes from the recycling of laminated glazing. Composition according to any one of claims 1 to 4, further comprising one or more crosslinking agents, preferably chosen from silanes, preferably from alkoxysilanes optionally comprising a functional group reactive with respect to carboxylic acid, carboxylate or hydroxy functions, such as an epoxy or amine group. Composition according to claim 5, in which the weight ratio between the content of crosslinking agent and the content of poly(vinyl acetal)-based resin is between 0.001 and 0.10, in particular between 0.002 and 0.

06. Composition according to any one of claims 1 to 6, 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. A composition according to claim 7, wherein the fillers are selected from calcium carbonate, clays, talc, dolomite, mica, silica sands, ground basalt, barium sulfate, kaolin, and mixtures of two or more of these compounds. A composition according to any one of claims 1 to 8, wherein said resin other than a poly(vinyl acetal) based resin is selected from styrene-acrylic resins, styrene-butadiene resins, acrylic resins, alkyd resins, and a mixture of two or more of these resins, preferably from alkyd resins. Composition according to any one of claims 1 to 9, further comprising from 0.1 to 20% by weight of pigments, relative to the total weight of the composition. Composition according to any one of claims 1 to 10, in which the total weight content of emulsifier(s) is between 0.1% and 10%. Composition according to any one of claims 1 to 11, in which the weight ratio between the plasticizer content and the poly(vinyl acetal) resin content is between 0.1 and 1, in particular between 0.2 and 0.

5. Composition according to any one of claims 1 to 12, in which the quantity 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. Composition according to any one of claims 1 to 13, in which the weight ratio between the content of particles of resin other than a resin based on poly(vinyl acetal) and the content of particles of a resin based on poly(vinyl acetal) is between 0.05 and 20, preferably between 0.1 and 10, or even between 1.0 and 3.

0. Waterproofing coating, obtained by applying and drying a composition as defined in any one of claims 1 to 14. Use of a waterproofing coating as defined in claim 15 as a waterproofing coating. A method of waterproofing a roof, terrace, balcony, wet room or facade comprising applying, to a substrate of said roof, terrace, balcony, wet room or facade, a composition according to any one of claims 1 to 14, to form a coating, then drying said coating to obtain a dry coating preferably having a thickness ranging from 0.1 to 2.0 mm. The method of claim 17, wherein the substrate is made of cementitious material.