EP3565925B1 - Process to coat textile materials - Google Patents

Description

The invention relates to a novel process for coating textile materials for the preparation of coated textiles having gas barrier properties.

Today, the use of activated carbon in gas filtration is the appropriate solution. However, activated carbon poorly traps toxic molecules of small size and polar and it must be impregnated with various chemicals suitable to compensate for this inefficiency. Activated carbon is found in various forms of mixed media with textiles: textiles impregnated with activated carbon and pressed, or activated carbon stuck to the fabric. In these cases, it becomes difficult to wash the garment without losing the original properties of the garment. To obtain good protection against chemical risks, a large amount of activated carbon is necessary, which makes the garment heavier. Furthermore, for protection against the projection of corrosive or / and toxic liquids, it is necessary to have a water-repellent fabric, either hydrophobic or both hydro- and oleophobic depending on the field of activity. Another desirable property for protective clothing is its resistance to wear by abrasion or washing.

The most efficient solutions are found for military applications. Protection against chemical and biological risks concerns various protective items (clothing, gloves, socks, balaclavas, masks) intended to prevent contact with toxic agents (in liquid or gaseous form) through the skin and respiratory tract. Thus, two ranges of protective articles exist: those made from waterproof materials and those using filtering and / or breathable (permeable) materials.

With a waterproof material, the wearer is perfectly protected from the external threat, but his body cannot exchange calories and humidity with the external environment. Prolonged wearing of this type of outfit therefore leads irreparably to hyperthermia problems which can become fatal. In order to overcome this problem, outfits using materials permeable to air and water vapor have been developed. These outfits use a set of textile materials with multiple layers. Currently, an NBC military protective suit (nuclear, bacteriological, chemical) consists of two layers with the following characteristics and functions. The outer layer, the main functions of which are to ensure the robustness of the outfit (resistance to abrasion and tearing) and to guarantee the non-penetration of war toxins in liquid form. The non-penetration of war toxins in liquid form corresponds to the water repellency function (hydrophobicity / oleophobicity). This function is obtained by surface treatment of the outer fabric with a fluorinated resin. The inner layer performs the function of filtering toxic substances in gaseous form. This function is obtained from activated carbon in different forms.

The state of the art brings out several inventions with respect to the inner layer (filtration function) of NBC military protective clothing. Activated charcoal can be found in different forms.

The patent application EP 1468732 A2 describes a monolayer of activated carbon which is bonded to a textile material as an inner lining. These activated carbon beads preferentially have a specific surface area of 900 to 1200 m ² / g.

In patents CN104492165 and CN102529254B , activated carbon beads (0.1 to 0.4 mm) are integrated into a textile (woven or not) by mixing them with hot-melt fibers, non-hot-melt fibers, a dispersing agent and water. The whole is heated between 80 and 150 ° C and compressed. The targeted applications concern filtration: gas masks, protective clothing, air filters.

The patent US6844122 describes a process making it possible to print particles, of activated carbon or of silica in particular, on a support which can be a textile (woven, non-woven, thread, etc.). Many applications are mentioned concerning filtration and protection (chemical, bacterial, against fire, etc.).

The patent application FR 2868956 A1 describes an activated carbon mesh whose adsorption properties are characterized by a preferred specific surface area of approximately 800 to 1200 m ² / g and by a preferred microporosity percentage of 80% to 100%.

In the patent application FR2678172A1 , activated carbon is in the form of polyurethane foam impregnated with activated carbon. The polyurethane foam layer is impregnated with activated carbon then compressed and contrc-glued on a fabric

The patent application TW200951269A describes the spraying of an activated carbon powder solution pretreated with a silane coupling agent onto a textile material, for filtration applications.

US2009 / 223411A1 The patent application describes the padding on a textile of an aqueous formulation comprising reactive silanes, for applications of face masks.

The patent application US2004 / 020367A1 describes a mask against pathogens, produced by coating a textile with a polymer network and optionally a chemical absorbent, such as activated carbon.

The patent application US20110114095A1 describes an activated carbon fabric impregnated with metals to obtain antiviral and virucidal properties. This textile is an activated carbon fabric impregnated with metal such as silver or copper known to be antibacterial and their derivatives (oxides, ions, nanoparticles).

The patent application WO 2015163969 A2 describes an activated carbon fabric containing metal oxide nanoparticles for gas filters or liquid purification. The specific surface area of the activated carbon fabric is given between 100 and 2000 m ² / g. The average diameter of the pores of the activated carbon is between 0.3 and 3 nm and represents 30 to 50% of the overall porosity.

An activated carbon fiber texture having bactericidal activity is described in the patent application FR 2819420 A1 . This activity is due to treatment with an adjuvant active against the effects of biological agents such as silver salts, quaternary ammonium salts, copper salts, organophosphorus compounds and mixtures thereof. The BET specific surface area of the activated texture is generally of the order of ^{approximately 1000 to 1200 m 2} / g.

Mixed textile / sol-gel media can be used in particle, gas and liquid filtration processes ( Surface Modification of Textiles, Q. Wei, 352 pages, Woodhead Publishing Series in Textiles, 1st Edition (September 9, 2009), ISBN-13: 978-1845694197, Chapter 11 "Surface modification of textiles for composite and filtration applications ").

The state of the art shows that it is, in most cases, to filter liquids and more particularly water. To retain pollutants such as heavy metals (Cu2 +, Hg2 +), siliceous precursors functionalized with amine functions, N- [3- (trimethoxysilyl) propyl] ethylenediamine, are used ( CN 101787654 ). Other porous membranes based on sol-gel, deposited on textile materials (viscose, polyester, polyethylene, polypropylene, styrene-butadiene) are obtained with pore sizes varying from 10 to 1000 nm and are used for the treatment of wastewater or drinking water ( CN 102371125 ). Liu et al. combine the use of activated carbon powder with a Ce3 + -TiO2 photocatalytic system, immobilized via a sol-gel membrane, to decontaminate water and in particular remove bisphenol A ( Chem. Eng. J., 2010, 156, 3, 553-556 , Adsorptive removal and oxidation of organic pollutants from water using novel membrane).

In the field of air and gas filtration with sol-gel textiles, there are very few studies. Chen et al. have proposed textile fibers (polyolefin, polyester, polyamide) impregnated with sol-gel based on vinyltrimethoxysilane as air filters for air conditioning units ( CN 1632215 ). Other filter textiles contain antibacterial agents ( FROM 102005031711 ) or fungicides, insecticides, repellents, odoriferous substances, essential oils ( FROM 202008016598 ). The sol-gel process is also at the origin of the patent application SK 500372013 and relates to a multifunctional textile with camouflage effect, hydrophobic, self-cleaning and antibacterial. However, the patent application relates more to the properties of the fabric (weight, composition, weave, mechanical properties) than to the sol-gel formulations themselves. It is only mentioned that a hydrophobic coating is obtained thanks to a mixture of organosilanes containing a biogen or nanoparticles based on silver ions, or a mixed hydrophobic / antibacterial coating.

The durability of the coating is also an important property of textiles used for protective clothing against civilian or military toxic chemicals. It also reflects the grip of the sol-gel on the textile. In the case of materials such as cotton or cellulose, the adhesion of the sol-gel is easily increased by the chemical condensation of silanol groups with the hydroxyl groups of the textile surface: the very nature of the sol-gel is sufficient to allow its grip on certain types of textile fibers ( J. Colloid Interf. Sci. 2005, 289, 249-261, Silane adsorption onto cellulose fibers: Hydrolysis and condensation reactions, M.-CB Salon, M. Abdelmouleh, S. Boufi, MN Belgacem, A. Gandini ). Chemical condensation of silicon alkoxides on cellulose is known to appear after heat treatment above 100 ° C ( Langmuir 2005, 18, 3203-3208, Interaction of Silane Coupling Agents with Cellulose, M. Abdelmouleh, S. Boufi, AB Salah, MN Belgacem, A. Gandini ). In practice, this is consistent since the sol-gel deposits on tissue, for example following the method described in FR2984343A1 , are preferably dried between 120 and 180 ° C in order to ensure the condensation of the sol-gel precursors, the elimination of solvents, and the condensation reaction of the acid anhydrides catalyzed by sodium hypophosphite.

The patent application of FR2984343A1 reports that the attachment of the sol-gel formulation to the tissue can be achieved by incorporating polycarboxylic acid and a catalyst (sodium hypophosphite). The role of the polycarboxylic acid is to promote the bridging between the material and the hydrolyzed siliceous precursors. The role of the catalyst is to ensure the grafting of the polycarboxylic acid on the material by catalyzing the formation of an anhydrous acid intermediate from the polycarboxylic acid (formation of an ester function with the alcohol functions free to the surface of the support). The objective of these two chemical compounds is therefore to improve the chemical adhesion of the polycondensed chains. The durability of the coating is said to be improved, in particular with regard to abrasion and washing. The tests relating to the durability to washing and to the abrasion resistance are reported for the only exemplary embodiment given using a sol-gel formulation from the hydrophobic silane hexadecyltrimethoxysilane.

In many cases the surface finish of the sol-gel is described as smooth with organic solvents while the same sol-gel prepared in water leads to coatings forming the cracks ( J. Sol-Gel Sci. Technol. 2005, 34, 103-109, Hydrophobic Silica Sol Coatings on Textiles - the Influence of Solvent and Sol Concentration, B. Mahltig, F. Audenaert, H. Böttcher ). According to Mahltig et al., This effect occurs mainly for synthetic fibers which are relatively hydrophobic. A certain amount of a solvent less polar than water improves the wetting of these materials and thus improves the resulting coating. The article by Mahltig et al. reports the influence of the solvent and the dilution of the sol-gel. The resulting cracks accelerate the abrasion of the fabric.

Other works mention the use of organosols (mixed organic-inorganic sol-gel precursors) for the impregnation of textiles. The patent US 8,926,744 B2 claims a large number of sol-gel formulations involving most of the silica precursors marketed and the absence of dispersing agents in the formulations. The most important objective aimed at in this patent is the stabilization of the formulations for the storage of the soil and its deferred use of the latter for various applications, such as coatings on solid substrates or the impregnation of textiles. with for the latter example a dilution of the formulation with water. The process involved, the Advantex process, is complex and involves several steps: the first corresponds to the reaction between three siliceous precursors, a functionalized alkoxysilane, a cyclic siloxane and a methylated and hydrogenated siloxane in the presence of catalysts to obtain catalysts. a mixed methylated and methylated-hydrogenated polysiloxane (product A). The 2nd step corresponds to the reaction of the latter with an allylic derivative (C3H5R) carrying a function in the presence of a catalyst (Pt) for the transformation of the SiH groups of compound A into Si-C2H4R carrying the function R. The reactions take place in organic solvents, and in particular in alcohols, which must be partially removed under partial vacuum at 150 ° C. Variants of this protocol are proposed, depending on the siloxanes and siliceous precursors used.

For applications concerning textiles, the authors claim the feel of the fabric (softness of the fabric treated), the resistance to the insertion of a sewing machine needle, the resistance to abrasion (from 9000 to 31000 cycles the Martindale test for various textiles and formulations). Filtration / barrier properties are not among the intended applications. Likewise, the concepts of porosity, distribution of pore sizes of the coating material and of the intrapore environment or even permeability are not mentioned.

The association of porous sol-gel materials with activated carbon has also been studied. In some studies, the use of activated carbon is only one step of the process making it possible to shape the porous sol-gel. Curdts et al. (Novel silica-based adsorbents with activated carbon structure, Microporous and Mesoporous Materials 210 (2015) 202-205 ) report for example a process for impregnating activated carbon with silicon by gas infiltration under partial vacuum with tetramethylsilane heated to 943 K. The activated carbon is then burnt to form porous silica granules. An application in the field of textile coatings is not mentioned. The patent application CN101318660A describes the synthesis of carbon beads from acetylene coated with sol-gel. These beads are then burnt to obtain empty and porous silica shells. No particular application is mentioned.

In other works, we find activated carbon associated with TiO ₂ produced by the sol-gel route. In the majority of cases, this association is carried out with the aim of optimizing the catalysis of TiO ₂ . Several authors describe the preparation of activated carbon grains coated with TiO ₂ by the sol-gel route. The targeted applications are the decontamination of water, in particular wastewater containing dyes ( Youji Li et al. Activated carbon supported TiO2-photocatalysis doped with Fe ions for continuous treatment of dye wastewater in a dynamic reactor, Journal of Environmental Sciences 2010, 22 (8) 1290-1296 ; KY Foo et al., Decontamination of textile wastewater via TiO2 / activated carbon composite materials, Advances in colloid and interface science 159 (2010) 130-143 ), degradation of Rhodamine B ( Meltem Asiltürk et al., TiO2-activated carbon photocatalysts: Preparation, characterization and photocatalytic activities, Chemical Engineering Journal 180 (2012) 354-363 ), as well as the decomposition of NH ₃ or formaldehyde ( Hongmei Hou, Hisashi Miyafuji, Haruo Kawamoto, Supercritically treated TiO2-activated carbon composites for cleaning ammonia, Journal of wood science 53 (2006) 533-538 ; Biao Huang et al., Photocatalytic activity of TiO2 crystallite-activated carbon composites prepared in supercritical isopropanol for the decomposition of formaldehyde, Journal of wood science 49 (2003) 79-85 ).

Juan Zhang et al. (Photocatalytic oxidation of dibenzothiophene using TiO2 / bamboo charcoal, Journal of materials science 44 (2009) 3112-3117 ) describe the deposition of a powder of TiO ₂ synthesized by the sol-gel route on activated carbon by impregnation. The objective is to decontaminate liquids containing dibenzothiophene.

Karran Woan et al. (Photocatalytic carbon-nanotube-TiO2 composites, Advanced materials 21 (2009) 2233-2239 ) describe the combination of TiO ₂ obtained by the sol-gel method by grafting or coating with carbon nanotubes. The aim here is also to improve the photocatalysis yield of TiO ₂ , with applications in the environmental sector.

Finally, combinations of sol-gel materials with activated carbon for applications in the field of filtration have been proposed. The objective of this work is to combine the complementary properties of the two materials, namely the mechanical resistance, the adjustable porosity and the adjustable polarity of the porous sol-gel material and the very high adsorption capacity of the activated carbon.

In the patent application CN104801279 , activated carbon in the form of particles is modified by impregnation of a sol-gel solution containing amine functions in order to improve its adsorption capacities, in particular of the CO ₂ contained in the air.

The patent application CN103334298 describes a textile composed of activated carbon fibers (0.1-1 mm) coated with silica (airgel - 5-30 wt%). The fibers are immersed in a sol-gel solution before being dried. Many properties are claimed: mechanical performance, adsorption, anti-fire, anti-virus properties, lightness. The targeted applications relate to high protection clothing, in particular for the biochemistry sector, firefighter and military equipment.

The state of the art shows that activated carbon is a material very widely used in the field of filtration where it is often associated with textiles. In addition, the processes for combining these two materials are quite varied. In the simplest cases, activated carbon particles are fixed to a textile by means of glue, however this has the drawback of blocking part of the pores of the activated carbon and reducing its filtration performance. In other processes, the activated carbon is trapped in a nonwoven or foam. Finally the solutions remaining in the state of the art consist in producing a fabric of activated carbon, either by weaving fibers of activated carbon, or by carrying out a heat treatment on a fabric of natural or synthetic fibers. However, they have a significant drawback, since the textiles obtained have low mechanical strength and are therefore relatively fragile.

On the other hand, activated carbon has been combined with soil-gels for several years. It is used in the majority of cases in order to increase the photocatalysis yield of TiO ₂ . Work associating activated carbon with a silicon-based sol-gel is rarer. The activated carbon can simply play the role of a support therein before being removed by carbonization, and is not present in the final product obtained. Finally, two patent applications describe the coating of activated carbon (particles or fibers) with a silicon-based sol-gel material, with applications in the field of filtration or high protection clothing. However, none of these solutions target the filtration of toxic compounds, the patent CN104801279 for CO ₂ sequestration and the patent CN103334298 aimed at thermal insulation in the case of clothing for firefighters and military personnel.

• pouvoir arrêter les produits toxiques polaires et non polaires et en particulier les molécules de petite taille et polaires que piège mal le charbon actif tout en laissant passer la vapeur d'eau et l'air ;
• assurer le compromis perméabilité à l'air / filtration.

In view of the foregoing, there is still a need for a textile material combining in particular high filtration capacity for different types of molecules, polar and non-polar, and mechanical strength. Such a material must in particular:

• be able to stop polar and non-polar toxic products and in particular small and polar molecules that the activated carbon does not trap well while allowing water vapor and air to pass through;
• ensure the air permeability / filtration compromise.

An aim of the invention is therefore to provide a method for manufacturing a simple and effective coated textile making it possible to achieve these performances.

It is to the credit of the inventors to have discovered, very unexpectedly and after much research, that it was possible to achieve this aim with a process which makes it possible to bind activated carbon to a textile material in a simple and efficient manner. by combining the application of activated carbon with the application of a sol-gel material.

A sol-gel material is a material obtained by a sol-gel process consisting in using as precursors metal alkoxides of formula M (OR) _x R ' _nx or M is a metal, in particular silicon, R an alkyl group and R' a group carrying one or more functions with n = 4 and x which can vary between 2 and 4. In the presence of water, the alkoxy groups (OR) are hydrolyzed to silanol groups (Si — OH). The latter condense to form siloxane bonds (Si-O-Si-). Small particles are formed, generally less than 1 µm in size, which aggregate and form clumps which remain in suspension without precipitating, forming a soil. The increase in clusters and their condensation increases the viscosity of the medium which gels. A porous solid material is obtained by drying the gel, with the expulsion of the solvent outside the polymer network formed (syneresis).

1. a) incorporer du charbon actif sous forme de poudre dans une composition de revêtement comprenant un solvant aqueux et au moins un précurseur organosilicé, dans laquelle le précurseur organosilicé représente 5 à 50% en volume par rapport à l'ensemble solvant aqueux et précurseur organosilicé,
2. b) imprégner le matériau textile par foulardage avec la composition de revêtement, et
3. c) sécher le matériau textile imprégné.

caractérisé en ce que la composition de revêtement est exempte d'acide polycarboxylique et de catalyseur.An object of the invention therefore relates to a process for coating a textile material, said process comprising the following steps:

1. a) incorporating activated carbon in powder form in a coating composition comprising an aqueous solvent and at least one organosilicon precursor, in which the organosilicon precursor represents 5 to 50% by volume relative to the whole aqueous solvent and organosilicon precursor,
2. b) impregnating the textile material by padding with the coating composition, and
3. c) drying the impregnated textile material.

characterized in that the coating composition is free from polycarboxylic acid and catalyst.

Unlike textiles impregnated with a coating composition comprising an aqueous solvent, an organosilicon precursor and polycarboxylic acid prepared according to the prior art and additionally containing activated carbon, the textiles obtained with the process according to the invention make it possible to filter polar and non-polar toxic gases. Unexpectedly and surprisingly and as demonstrated in Example 2, the incorporation of a polycarboxylic acid modifies the sol-gel making it unsuitable for an application in gas filtration, in particular polar.

Unlike impregnated textiles prepared according to the prior art with a coating composition comprising an aqueous solvent, an organosilicon precursor and polycarboxylic acid and additionally containing activated carbon, the textiles obtained with the process according to the invention make it possible to filter polar and non-polar toxic gases. Unexpectedly and surprisingly and as demonstrated in Example 3, the incorporation of a polycarboxylic acid modifies the sol-gel making it unsuitable for an application in gas filtration, in particular polar.

The coating composition is additionally free of catalyst. In fact, due to the absence of polycarboxylic acid, the coating composition according to the invention does not require the presence of a catalyst for the formation of an anhydrous acid intermediate from the acid either. polycarboxylic, such as phosphorus catalysts such as sodium hypophosphite. Thus, the coating composition is in particular free of such a catalyst. The term catalyst within the meaning of the invention also includes acids, in particular mineral acids, such as hydrochloric acid, and monocarboxylic acids.

Advantageously, the coating composition is further free of surfactant. Indeed, the presence of surfactant would modify the sol-gel by inducing the formation of a network of large pores, either mesopores (20-500 Å) or even macropores (> 500 Å), which would be detrimental to the property. filtration.

The impregnated textile material according to the invention is flexible, light, breathable, water-repellent, and has barrier properties against polar and non-polar toxic gases.

The textile material used can be of any type. It may for example be a fabric, a nonwoven, such as a felt, or a knitted fabric, preferably a fabric or a nonwoven such as a felt. Advantageously, the textile material comprises fibers comprising hydrolyzable functions, such as hydroxyl functions. An example of such a fiber is cellulose present in natural fibers such as cotton or artificial fibers such as viscose. Preferably, they are viscose fibers. The fibers comprising hydrolyzable functions can be used alone, as a mixture with one another and / or as a mixture with other synthetic fibers such as polyamide, polyamide / imide, polymeta-phenylene terephthalamide, polyparphenylene terephthalamide, d acrylic, modacrylic, polyesterterephthalate, oxidized polyacrylonitrile. In a preferred embodiment, the textile material is a material based on an intimate blend of viscose and synthetic fibers, preferably polyamide fibers, in particular aromatic polyamide. Examples of such a fabric are Kermel® / Lenzing FR® 50: 50 and Conex® / Lenzing FR® 50: 50. In another embodiment, the textile material is a nonwoven, in particular a felt. An example of such a felt is that of Duflot Industries in Nomex®.

The aqueous solvent used in the coating composition can be water or a mixture of water and an organic solvent, in particular polar, protic or aprotic. This organic solvent may for example be chosen from linear C1 to C4 aliphatic alcohols, in particular methanol, ethanol and propan-1-ol. Preferably, the organic solvent is ethanol. The aqueous solvent advantageously contains 50% to 100% by volume of water.

The aqueous solvent advantageously represents 50 to 92% by volume, preferably 55 to 80% by volume and more preferably still 60 to 70% by volume of the coating composition.

The organosilicon precursor used in the coating composition can consist of a single organosilicon precursor or a mixture of organosilicon precursors. It is advantageously chosen from tetramethoxysilane (TMOS), tetraethoxysilane (TEOS), methyl trimethoxysilane (MTM), methyl triethoxysilane (MTE), phenyltrimethoxysilane (PhTMOS), phenyltriethoxysilane, a fluoxylane (Phoxysilane), a fluoxylane (Phoxysilane), a fluoxysilane (Phoxysilane), a fluoxysilane (PhoTEOS) and a fluoxysilane (TEOS) ETHoxysilane (ETH-O-TEOS-ETH-O-TEOS-OH-O-TEOS-OH-O-TEOS-OH-ET-OH-ET-OH-ET-OH-TEOS chloroalkylmethoxysilane, a chloroalkylethoxysilane, an aminopropyltriethoxysilane, (3-glycidyloxypropyl) trimethoxysilane (GPTMOS) and mixtures thereof, preferably from tetramethoxysilane (TMOS), methyl trimethoxysilane (MTM), phenyltrimethoxysilane (PhTMOS), a fluoroalkyltrimethoxysilane, a chloroalkylmethoxysilane, an aminopropyltriethoxyltriethoxylane (TM) and 3TM (3) aminopropyltriethoxysilane, an aminopysiltriethoxyltriethoxyl (TM) and 3TM (3) -propyletriethoxyl (TM) and 3-propyletriethoxyl (TM) (3) and 3-propyletriethoxyl (GPTMOS) (3) mixtures, more preferably from tetramethoxysilane (TMOS), methyl trimethoxysilane (MTM), 1H, 1H, 2H, 2H-perfluoroheptadecyltriethoxysilane (17FTMOS), aminopropyl triethoxysilane (APTES), phenyltrimethoxysilane (TMOS), phenyltrimethoxysilane (TM). In a particular variant, the organosilicon precursor is chosen from tetramethoxysilane (TMOS), tetraethoxysilane (TEOS), phenyltrimethoxysilane, methyl trimethoxysilane (MTM), methyl triethoxysilane (MTE), phenyltrimethoxysilane (TEOS), phenyltrimethoxysilane, methyl trimethoxysilane (MTM), methyl triethoxysilane (MTE), phenyltrimethylethoxysilane (Phenoxysilane) (Phoxysilane) a fluoroalkyltrimethoxysilane, a fluoroalkyltriethoxysilane, an aminopropyltriethoxysilane, (3-glycidyloxypropyl) trimethoxysilane (GPTMOS) and their mixtures, preferably from tetramethoxysilane (TMOS), methyl phenysiltrimethilaneTM (TMOStrimoxyTM) (TMOS), MethyltroxysiltrimethilaneTM (TMOS) (TMOStrimethilaneTM) (TMOStrimethilaneTM) (TMOS) aminopropyltriethoxysilane, (3-glycidyloxypropyl) trimethoxysilane (GPTMOS) and their mixtures, more preferably from tetramethoxysilane (TMOS), methyl trimethoxysilane (MTM), 1H, 1H, 2H, 2H-perfluoroheptopoxropadecyltriane (17TEopoxysilane) triethoxysilane (APTES), phenyltrimethoxysilane (PhTMOS) and mixtures thereof.

In one embodiment, the organosilicon precursor is tetramethoxysilane. In another embodiment, the organosilicon precursor is a mixture of tetramethoxysilane and a precursor chosen from methyl trimethoxysilane (MTM), methyl triethoxysilane (MTE), phenyltrimethoxysilane (PhTMOS), phenyltriethoxysilane (PhoxTEOS), a fluorohydrin (PhoxTEOS) a fluoroalkyltriéthoxysilane a chloroalkylméthoxysilane a chloroalkyléthoxysilane, an aminopropyltriethoxysilane, (3-glycidyloxypropyl) trimethoxysilane (GPTMOS) and mixtures thereof, preferably from methyl trimethoxysilane (MTM), phenyltrimethoxysilane (PhTMOS), a fluoroalkyltriméthoxysilane a chloroalkylméthoxysilane, an aminopropyltriethoxysilane , (3-glycidyloxypropyl) trimethoxysilane (GPTMOS) and their mixtures, more preferably from methyl trimethoxysilane (MTM), 1H, 1H, 2H, 2H-perfluoroheptadecyltriethoxysilane (17FTMOS), aminopropyltriethoxysilane (APTRimoxysilane) (PhTMOS) and their mixtures. Alternatively, the mixture contains neither chloroalkylmethoxysilane nor chloroalkylethoxysilane. Preferred organosilicate precursor mixtures include mixtures of tetramethoxysilane (TMOS) with methyl trimethoxysilane (MTM), with aminopropyl triethoxysilane (APTES), with 1H, 1H, 2H, 2H-perfluoroheptadecyltrimethoxysilane), withTM deTM aminopropyl triethoxysilane (APTES) and 1H, 1H, 2H, 2H-perfluoroheptadecyltriethoxysilane (17FTOS). Particularly good bonding and filtration performances were obtained with mixtures of TMOS and PhTMOS respectively.

When using a mixture of tetramethoxysilane and one or more other organosilicon precursors, the molar proportions of tetramethoxysilane (TMOS) / other organosilicon precursor (s) can be varied between 100/0 and 50/50, preferably between 90/10 and 75/25.

The organosilicon precursor advantageously represents 5 to 50% by volume, relative to the aqueous solvent and organosilicon precursor combination. If the aqueous solvent is water, the organosilicon precursor preferably represents 8 to 35% by volume relative to the whole aqueous solvent and organosilicon precursor. By using a mixture of water and an organic solvent, in particular ethanol (eg 90/10 by volume), the precursor can represent up to 50% by volume relative to the aqueous solvent assembly. and organosilicon precursor.

The activated carbon used for the present invention can be of plant or animal origin. Those skilled in the art will choose it as a function of the properties, in particular of filtration, sought. Thus, it is possible to use different forms of activated carbon, such as, for example, beads, powder, granules or fibers. The activated carbon can be mixed at different concentrations with the coating composition (sol-gel composition) to modulate the quantity of activated carbon deposited on the textiles after impregnation.

The incorporation of the activated carbon into the sol-gel solution can take place from the start of the reaction until the moment of impregnation of the textile material. It can for example be added at the same time as the sol-gel precursors.

According to a first particular embodiment, the coating composition is applied directly to the textile material. This strategy directly uses the functionality of the organosilicon precursors used for the barrier function for the attachment of the sol-gel to the textile, in particular via hydroxyl functions at the surface.

According to a second particular embodiment, the method according to the invention comprises, before step b), a step of applying a pre-coating composition comprising an organic solvent and a zirconium alkoxide, said pre-coating composition. -coating being free of polycarboxylic acid. Due to the absence of polycarboxylic acid, the precoating composition according to the invention also does not require the presence of a catalyst for the formation of an anhydrous acid intermediate from the polycarboxylic acid. , such as phosphorus catalysts such as sodium hypophosphite. Thus, the precoating composition is advantageously free of such a catalyst.

Zr ⁴⁺ has a high coordination number (+7) which promotes adhesion to the textile material via the complexation with the functionalities coming from the textile. The application of the coating composition in step b) covers this first tie layer to form the “barrier” coating. The zirconium alkoxide can be chosen from tetra-n-propyl zirconate ( CAS 23519-77-9 ), tetra-n-butyl zirconate ( CAS 1071-76-7 ), tetra- iso -propyl zirconate ( CAS 14717-56-7 ), tetra-tert-butyl zirconate (2081-12-1), bis (diethyl citrato) -dipropyl zirconate ( CAS 308847-92-9 ), bis (2,2,6,6-tetramethyl-3,5-heptanedionate) -di- isopropyl zirconate ( CAS 204522-78-1 ), preferably tetra-n-propyl zirconate (TPOZ) will be chosen.

The textile material is impregnated by padding with the coating composition containing activated carbon. The padding comprises a step of impregnating the textile material in the soil followed by a step of pressing under pressure which allows the excess soil to be evacuated. Compared to other coating technique, such as for example dip-coating, this technique makes it possible to obtain a uniform distribution of the soil as well as a better impregnation of the soil in the fabric. The scanning electron microscopy images show that the application of the coating composition according to the invention by padding results in a sheathing of the textile fibers. The dip coating on the other hand results in a non-homogeneous deposit and essentially on the surface because it consists of the soaking of the textile material in the coating solution followed by the exit of the textile material vertically. This vertical exit is inevitably accompanied by the formation of a downward deposition gradient of the textile material. In addition, simple soaking in the coating solution does not make it possible to guarantee impregnation of the textile material and thus sheathing of the fibers. This sheathing of the fibers is however important for imparting the desired properties to the textile material. Particularly good results in terms of fiber sheathing have been obtained with coating compositions having a dynamic viscosity less than or equal to 10 mPa.s (10 cP). The dynamic viscosity can for example be measured using a “Physica MCR 301” rheometer sold by the company Anton Paar as described in the examples below.

Step b) of impregnation of the textile material by padding can be carried out once or repeated several times. The process according to the invention can thus comprise several, in particular 1 to 3, successive cycles of impregnation of the textile material by padding.

In one embodiment, the textile material used in step b) of the process according to the invention is dried prior to impregnation with the coating composition in order to remove water from the surface. This drying is particularly advantageous in the case of textile materials incorporating cellulosic fibers such as cotton or viscose. Those skilled in the art will know how to adapt the temperature and the drying time as a function of the textile material and the water content, in particular at the surface. Advantageously, the textile material is dried at a temperature of 80 to 180 ° C, preferably 100 to 150 ° C, more preferably about 120 ° C. The drying time is advantageously a few minutes, for example 2 to 10 minutes, in particular 2 to 5 minutes.

Another subject of the invention is a coating composition comprising an aqueous solvent, an organosilicon precursor and activated carbon in powder form as described above.

The subject of the invention is also an impregnated textile material obtained by the coating process according to the invention described above. It is therefore a textile material impregnated with a sol-gel material and activated carbon in powder form. All the details and embodiments set out above for the nature of the textile material, the sol-gel material and the activated carbon are also valid for the textile material impregnated according to the invention. The impregnated textile material according to the invention is characterized in particular in that it has a specific surface area S _BET (determined from the adsorption isotherms using the Brunauer, Emmet and Teller (BET) model) of between 600 ± 50 and 950 ± 80 m ² .g ^-1 , in particular between 700 ± 60 and 940 ± 80 m ² .g ^-1 . The porosity of the impregnated textile material according to the invention was determined from the adsorption isotherms using the model based on the density functional theory (DFT, for English: Density Functional Theory). The proportion of micropores (<20 Å) is preferably greater than 40%, and more preferably still greater than 50%. The proportion of mesopores (20 Å - 500 Å) is preferably less than 60%, and more preferably still less than 50%. The textile material is preferably free of macropores (> 500 Å). The basis weight of the sol-gel material can vary from 10 to 435 g / m ² , preferably from 20 to 400 g / m ² , more preferably from 30 to 300 g / m ² .

The impregnated textile material according to the invention finds a particular application for the filtration of gases, in particular for personal protective equipment such as for example clothing, in particular against toxic chemicals, but also for textiles intended to protect the respiratory tract (masks ), textiles that absorb unwanted odors such as frying or tobacco, such as for example consumable filters. The invention therefore also relates to a filter, in particular a gas filter, comprising the textile material according to the invention.

A particular object of the invention is personal protective equipment comprising the textile material according to the invention. This personal protective equipment may for example be a full suit, pants, jacket, gloves, balaclavas, socks, masks. Thanks to the functional properties, in particular of filtration of polar and non-polar toxic gases of the textile material according to the invention, the personal protective equipment is particularly suited to NBC risks (nuclear, bacteriological, chemical). Thus, in one embodiment, the personal protective equipment is NBC personal protective equipment.

Non-limiting examples of embodiment of the invention are described below.

FIGURES

• Figure 1 : SEM images of fabric A before impregnation.
• Figure 2 : SEM images of fabric B before impregnation.
• Figure 3 : SEM images of fabric C before impregnation.
• Figure 4 : SEM images of fabric A with impregnation of a sol-gel solution containing 40 g / l of activated carbon (D ₁ ).
• Figure 5 : SEM images of fabric A with impregnation of a sol-gel solution containing 100 g / l of activated carbon (D ₂ ).
• Figure 6 : SEM images of fabric A with impregnation of a sol-gel solution containing 100 g / l of activated carbon (D ' ₁ ).
• Figure 7 : SEM images of fabric A with impregnation of a sol-gel solution containing 100 g / l of activated carbon (D ' ₂ ).
• Figure 8 : SEM images of fabric B with impregnation of a sol-gel solution containing 100 g / l of activated carbon (D ₂ ).
• Figure 9 : SEM images of fabric C with impregnation of a sol-gel solution containing 100 g / l of activated carbon (D ₂ ).
• Figure 10 : Photos of fabric A: (A) before impregnation, (B) place after impregnation with formula A ₁ , (C) reverse after impregnation with formula A ₁ .
• Figure 11 : Photos of fabric A: (A) before impregnation, (B) place after impregnation with formula A ₂ , (C) reverse after impregnation with formula A ₂ .
• Figure 12 : Photos of fabric B: (A) before impregnation, (B) place after impregnation with formula D ₂ , (C) reverse after impregnation with formula D ₂ .
• Figure 13 : Photos of fabric C: (A) before impregnation, (B) place after impregnation with formula D ₂ , (C) reverse after impregnation with formula D ₂ .
• Figure 14 : (A) Schematic view of the components of the fabric drop measurement tool; (B) Schematic diagram of the fabric drop measurement.
• Figure 15 : (A) Photo of the initial fabric in the fabric drop measurement tool; (B) Photo of the fabric impregnated with formula D ₂ '.
• Figure 16 : Comparison of the standardized methyl salicylate piercing curves with a deposit of 20 g / m ² on fabric A with formulas D ₂ (strategy I) and D ₂ '(strategy II).
• Figure 17 : Comparison of the normalized toluene drilling curves with a deposit of 20 g / m ² on fabric A with formulas D ₂ (strategy I), D ₂ '(strategy II), E ₂ (strategy I) and E ₂ '(strategy II).

EXAMPLES Chemicals used

• Tetramethoxysilane (No. CAS: 681-84-5 ) (TMOS, Acros Organics, 99%);
• Methyl trimethoxysilane (No. CAS: 1185-55-3 ) (MTM, Sigma-Aldrich, 98%);
• 1H, 1H, 2H, 2H-Perfluoroheptadecyltriethoxysilane (No. CAS: 101947-16-4 ) (17FTMOS, Sigma-Aldrich, 97%);
• Aminopropyl triethoxysilane (No. CAS: 919-30-2 ) (APTES, Acros Organics, 99%);
• Phenyl trimethoxysilane (No. CAS: 2996-92-1 ) (PhTMOS, TCI,>98%);
• Ethanol (No. CAS: 64-17-5 ) (Merck, Uvasol for spectroscopy);
• Acetonitrile (No. CAS: 75-05-8 ) (Merck, Lichrosolv gradient grade for liquid chromatography);
• Succinic acid (No. CAS: 110-15-6 ) (Sigma-Aldrich, Reagent Plus ≥99.0%);
• Sodium hypophosphite (No. CAS: 123333-67-5 ) (Sigma-Aldrich, hydrate).

Example 1: Preparation of coated fabrics

The formulations according to strategies I, II and III described below were deposited on pieces of 5 cm x 10 cm to 21 cm x 30 cm of fabric: fabric A in (fabric in Kermel® / Lenzing FR® 50: 50 (Kermel, Colmar, France) (Lenzing AG, Lenzing, Austria), fabric B (fabric in Conex® / Lenzing FR® 50:50 (Teijin Aramid BV, Arnhem, the Netherlands) (Lenzing AG, Lenzing, Austria) , and fabric C (Nomex® felt (Dupont, Wilmington, Delaware, United States)) by full bath impregnation and squeezing (padding principle) then the fabrics were dried in an oven for 2 min at 120 ° C and left at rest for 24 hours at ambient temperature and atmospheric pressure in the laboratory The initial quantity deposited varies between 10 and 435 g / m ^2. The surface mass of the sol-gel material is deduced by weighing the fabric before and after impregnation.

I. Preparation of coated fabrics according to the bonding strategy described in FR 2984343 A1 (with polycarboxylic acid) Formulation A1

In a hermetically sealed glass bottle, 0.131 g of succinic acid and 0.140 g of sodium hypophosphite are mixed in 17.73 mL of ultra pure water. The mixture is stirred at mark 4 on the IKA WERKE RO10 power multiple stirrer plate (approximately 500 rpm) and at room temperature (20-22 ° C) until the polyacid and the catalyst have dissolved. Then 0.805 g of activated carbon and 2.300 mL of TMOS are added to the initial mixture.

Dynamic viscosity: 3.5 cP (mPa.s)

The deposition of this formula on textiles indicates a basis weight of 29 g / m ² .

Formulation A ₂

In a hermetically sealed glass bottle, 0.200 g of succinic acid and 0.212 g of sodium hypophosphite are mixed in 27.03 mL of ultra pure water. The flask is placed at approximately 45 ° C in a water bath covered with aluminum foil, on a TECHLAB MAGNETIC STIRRER SH-4C heating stirrer (set point: 55 ° C), and mixed at approximately 400-500 rpm until the polyacid and the catalyst have dissolved. Then 3.057 g of activated carbon and 3.600 mL of TMOS are added to the initial mixture.

Dynamic viscosity: 5.4 cP (mPa.s)

The deposition of this formula on textiles indicates a basis weight of 37 g / m ² .

Formulation B

In a hermetically sealed glass bottle, 0.333 g of succinic acid and 0.354 g of sodium hypophosphite are mixed in 45.06 mL of ultra pure water. The mixture is stirred at mark 4 on the IKA WERKE RO10 power multiple stirrer plate (approximately 500 rpm) and at room temperature (20-22 ° C) until the polyacid and the catalyst have dissolved. Then 2.033 g of activated carbon, 3.000 mL of TMOS and 2.780 mL of MTM are added to the initial mixture.

Dynamic viscosity: 2.0 cP (mPa.s)

The deposition of this formula on textiles indicates a basis weight of 22 g / m ² .

Formulation C ₁

In a hermetically sealed glass flask, 0.267 g of succinic acid and 0.284 g of sodium hypophosphite are mixed in 18.02 mL of ultra pure water and 18.02 mL of ethanol. The mixture is stirred at mark 4 on the IKA WERKE RO10 power multiple stirrer plate (approximately 500 rpm) and at room temperature (20-22 ° C) until the polyacid and the catalyst have dissolved. Then 1.643 g of activated carbon, 4.800 mL of TMOS and 0.226 mL of APTES are added to the initial mixture.

Dynamic viscosity: 18.7 cP (mPa.s)

The deposition of this formula on textiles indicates a basis weight of 27 g / m ² .

Formulation C ₂

In a hermetically sealed glass flask, 0.268 g of succinic acid and 0.284 g of sodium hypophosphite are mixed in 18.02 mL of ultra pure water and 18.02 mL of ethanol. The mixture is stirred at mark 4 on the IKA WERKE RO10 power multiple stirrer plate (approximately 500 rpm) and at room temperature (20-22 ° C) until the polyacid and the catalyst have dissolved. Then 4.107 g of activated carbon, 4.800 mL of TMOS and 0.226 mL of APTES are added to the initial mixture.

Dynamic viscosity: 82.5 cP (mPa.s)

The deposition of this formula on textiles indicates a basis weight of 36 g / m ² .

Formulation D ₁

In a hermetically sealed glass bottle, 0.237 g of succinic acid and 0.252 g of sodium hypophosphite are mixed in 15.98 mL of ultra pure water and 15.98 mL of ethanol. The mixture is stirred at mark 4 on the IKA WERKE RO10 power multiple stirrer plate (approximately 500 rpm) and at room temperature (20-22 ° C) until the polyacid and the catalyst have dissolved. Then 1.454 g of activated carbon, 4.000 mL of TMOS and 0.402 mL of APTES are added to the initial mixture.

Dynamic viscosity: 13.5 cP (mPa.s)

The deposition of this formula on textiles indicates a basis weight of 27 g / m ² .

Formulation D ₂

In a hermetically sealed glass flask, 0.296 g of succinic acid and 0.314 g of sodium hypophosphite are mixed in 19.97 mL of ultra pure water and 19.97 mL of ethanol. The mixture is stirred at mark 4 on the IKA WERKE RO10 power multiple stirrer plate (approx. 500 rpm) and at room temperature (20-22 ° C) until the polyacid and the catalyst have dissolved. Then 4.545 g of activated carbon, 5,000 mL of TMOS and 0.502 mL of APTES are added to the initial mixture.

Dynamic viscosity: 12.4 cP (mPa.s)

The deposition of this formula on textiles indicates a basis weight of 42 g / m ² .

Formulation E ₁

In a hermetically sealed glass bottle, 0.127 g of succinic acid and 0.135 g of sodium hypophosphite are mixed in 8.57 mL of ultra pure water. The mixture is stirred at mark 4 of the IKA WERKE RO10 power multiple stirrer plate (approximately 500 rpm) and at room temperature (20-22 ° C) until the polyacid and the catalyst have dissolved, before adding 0.773 g of activated carbon. In a second hermetically sealed glass vial, 8.57 mL of ethanol, 0.337 mL of 17FTMOS, 2.100 mL of TMOS and 0.108 mL of APTES are mixed. The contents of the second flask are then poured into the first, which is kept under stirring.

Dynamic viscosity: 37.0 cP (mPa.s)

The deposition of this formula on textiles indicates a basis weight of 30 g / m ² .

Formulation E ₂

In a hermetically sealed glass bottle, 0.127 g of succinic acid and 0.135 g of sodium hypophosphite are mixed in 8.57 mL of ultra pure water. The mixture is stirred at mark 4 on the IKA WERKE RO10 power multiple stirrer plate (approximately 500 rpm) and at room temperature (20-22 ° C) until the polyacid and the catalyst have dissolved, before adding 1.937 g of activated carbon. In a second hermetically sealed glass vial, 8.57 mL of ethanol, 0.337 mL of 17FTMOS, 2.100 mL of TMOS and 0.108 mL of APTES are mixed. The contents of the second flask are then poured into the first, which is kept under stirring.

Dynamic viscosity: 50.0 cP (mPa.s)

The deposition of this formula on textiles indicates a basis weight of 44 g / m ² .

Formulation F ₁

In a hermetically sealed glass bottle, 0.138 g of succinic acid and 0.147 g of sodium hypophosphite are mixed in 9.28 mL of ultra pure water. The mixture is stirred at mark 4 on the IKA WERKE RO10 power multiple stirrer plate (approx. 500 rpm) and at room temperature (20-22 ° C) until the polyacid and the catalyst have dissolved, before adding 0.840 g of activated carbon. In a second hermetically sealed glass vial, 9.28 mL of ethanol, 0.365 mL of 17FTMOS, 2.200 mL of TMOS and 0.233 mL of APTES are mixed. The contents of the second flask are then poured into the first flask and the mixture kept under agitation.

Dynamic viscosity: 20.0 cP (mPa.s)

The deposition of this formula on textiles indicates a basis weight of 31 g / m ² .

Formulation F ₂

In a hermetically sealed glass bottle, 0.138 g of succinic acid and 0.146 g of sodium hypophosphite are mixed in 9.28 mL of ultra pure water. The mixture is stirred at mark 4 on the IKA WERKE RO10 power multiple stirrer plate (approximately 500 rpm) and at room temperature (20-22 ° C) until the polyacid and the catalyst have dissolved, before adding 2.104 g of activated carbon. In a second hermetically sealed glass vial, 9.28 mL of ethanol, 0.365 mL of 17FTMOS, 2.200 mL of TMOS and 0.233 mL of APTES are mixed. The contents of the second flask are then poured into the first flask and the mixture kept under agitation.

Dynamic viscosity: 20.0 cP (mPa.s)

The deposition of this formula on textiles indicates a basis weight of 40 g / m ² .

II. Preparation of coated fabrics using a one-step polycarboxylic acid-free bonding strategy Formulation A ₁

In a hermetically sealed glass bottle, 2.381 g of activated charcoal and then 7.000 mL of TMOS are added to a volume of 52.56 mL of ultra pure water. The mixture is stirred at room temperature (20-22 ° C) at mark 4 of the IKA WERKE RO10 power multiple stirrer plate (approximately 500 rpm).

Dynamic viscosity: 3.1 cP (mPa.s)

The deposition of this formula on textiles indicates a basis weight of 21 g / m ² .

Formulation A ₂ '

In a hermetically sealed glass bottle, 5.956 g of activated charcoal and then 7,000 mL of TMOS are added to a volume of 52.56 mL of ultra pure water. The mixture is stirred at temperature (20-22 ° C) at mark 4 on the IKA WERKE RO10 power multiple stirrer plate (approx. 500 rpm).

Dynamic viscosity: 7.3 cP (mPa.s)

The deposition of this formula on textiles indicates a basis weight of 36 g / m ² .

Formulation D ₁ '

In a hermetically sealed glass bottle, 1.816 g of activated charcoal is mixed with a volume of 19.97 mL of ultra pure water. In a second hermetically sealed glass vial, 19.97 mL of ethanol, 5,000 mL of TMOS and 0.502 mL of APTES are mixed. The contents of the second vial are then poured into the first vial and the mixture is stirred at room temperature (20-22 ° C) at mark 4 of the IKA WERKE RO10 power multiple stirrer plate (approximately 500 rpm).

The deposition of this formula on textiles indicates a basis weight of 28 g / m ² .

Formulation D ₂ '

In a hermetically sealed glass bottle, 4.541 g of activated carbon are mixed with a volume of 19.97 mL of ultra pure water. In a second hermetically sealed glass vial, 19.97 mL of ethanol, 5,000 mL of TMOS and 0.502 mL of APTES are mixed. The contents of the second vial are then poured into the first vial and the mixture is stirred at room temperature (20-22 ° C) at mark 4 of the IKA WERKE RO10 power multiple stirrer plate (approximately 500 rpm).

Dynamic viscosity: 10-12 cP (mPa.s)

The deposition of this formula on textiles indicates a basis weight of 33 g / m ² .

Formulation E ₁ '

In a hermetically sealed glass bottle, 1.129 g of activated charcoal is mixed with a volume of 12.24 mL of ultra pure water. In a second hermetically sealed glass vial, 12.24 mL of ethanol, 0.482 mL of 17FTMOS, 3.000 mL of TMOS and 0.154 mL of APTES are mixed. The contents of the second vial are then poured into the first vial and the mixture is stirred at room temperature (20-22 ° C) at mark 4 of the IKA WERKE RO10 power multiple stirrer plate (approximately 500 rpm).

The deposition of this formula on textiles indicates a basis weight of 17 g / m ² .

Formulation E ₂ '

In a hermetically sealed glass bottle, 2.813 g of activated charcoal is mixed with a volume of 12.24 mL of ultra pure water. In a second hermetically sealed glass vial, 12.24 mL of ethanol, 0.482 mL of 17FTMOS, 3.000 mL of TMOS and 0.154 mL of APTES are mixed. The contents of the second vial are then poured into the first vial and the mixture is stirred at room temperature (20-22 ° C) at mark 4 of the IKA WERKE RO10 power multiple stirrer plate (approximately 500 rpm).

The deposition of this formula on textiles indicates a basis weight of 35 g / m ² .

Formulation G ₁ '

In a hermetically sealed glass bottle, 0.200 g of activated carbon is mixed with a volume of 17.52 mL of ultra pure water. Then 2.100 mL of TMOS and 0.293 mL of PhTMOS are added and the mixture is stirred at room temperature (20-22 ° C) at mark 4 of the IKA WERKE RO10 power multiple shaker plate (approximately 500 rpm).

Dynamic viscosity: 1.9 cP (mPa.s)

The deposition of this formula on textiles indicates a basis weight of 18 g / m ² .

Formulation G ₂ '

In a hermetically sealed glass bottle, 0.397 g of activated carbon is mixed with a volume of 17.52 mL of ultra pure water. Then 2.100 mL of TMOS and 0.293 mL of PhTMOS are added and the mixture is stirred at room temperature (20-22 ° C) at mark 4 of the IKA WERKE RO10 power multiple shaker plate (approximately 500 rpm).

Dynamic viscosity: 2.8 cP (mPa.s)

The deposition of this formula on textiles indicates a basis weight of 19 g / m ² .

Formulation H ₁ '

In a hermetically sealed glass bottle, 0.411 g of activated charcoal is mixed with a volume of 18.02 mL of ultra pure water. Then 1.800 mL of TMOS and 0.753 mL of PhTMOS are added and the mixture is stirred at room temperature (20-22 ° C) at mark 4 of the IKA WERKE RO10 power multiple stirrer plate (approximately 500 rpm).

Dynamic viscosity: 2.2 cP (mPa.s)

The deposition of this formula on textiles indicates a basis weight of 20 g / m ² .

H ₂ 'formulation

In a hermetically sealed glass bottle, 0.823 g of activated charcoal is mixed with a volume of 18.02 mL of ultra pure water. Then 1.800 mL of TMOS and 0.753 mL of PhTMOS are added and the mixture is stirred at room temperature (20-22 ° C) at mark 4 of the IKA WERKE RO10 power multiple stirrer plate (approximately 500 rpm).

Dynamic viscosity: 13.0 cP (mPa.s)

The deposition of this formula on textiles indicates a basis weight of 26 g / m ² .

• La stratégie I d'accrochage selon FR 2984343 A1 est réalisée avec l'ajout de l'acide succinique et de l'hypophosphite de sodium ;
• La stratégie II d'accrochage en une étape est l'accrochage direct avec les précurseurs silicés utilisés ;

Tableau 1 Stratégie I Précurseurs sol-gel Formules Concentration en charbon actif (g/l) Temps de réaction sol-gel avant dépôt Dépôt de sol-gel avec charbon actif (g/m²) sur l'étoffe A (Moyennes) TMOS A₁ 40,2 65h 29 TMOS A₂ 99,8 24h 37 TMOS/MTM B 40,0 6 jours 22 TMOS/ APTES C₁ 40,0 6h 27 TMOS/ APTES C₂ 100,0 25h 36 TMOS/ APTES D₁ 40,0 2h 27 TMOS/ APTES D₂ 100,0 2h 42 1h45 37 (Etoffe B) 1h45 435 (Etoffe C) TMOS/ APTES/17FTMOS E₁ 40,0 5h 30 TMOS/ APTES/17FTMOS E₂ 100,1 16h30 44 TMOS/ APTES/17FTMOS F₁ 40,0 1h 31 TMOS/ APTES/17FTMOS F₂ 100,2 2h20 40 Tableau 2 Stratégie II Précurseurs sol-gel Formule Concentration en charbon actif (g/l) Temps de réaction sol-gel avant dépôt Dépôt de sol-gel avec charbon actif (g/m²) sur l'étoffe A (Moyennes) TMOS A₁' 40,0 14 jours 21 TMOS A₂' 100,0 28 jours 36 TMOS/ APTES D₁' 40,0 1 min 28 TMOS/ APTES D₂' 100,0 35 min 33 TMOS/ APTES/17FTMOS E₁' 40,1 5 min 17 TMOS/ APTES/17FTMOS E₂' 100,0 10 jours 35 TMOS/PhTMOS G₁' 10,0 3 jours 18 TMOS/PhTMOS G₂' 20,0 10 jours 19 TMOS/PhTMOS H₁' 20,0 3 jours 20 TMOS/PhTMOS H₂' 40,0 21 jours 26 Tables 1 and 2 below summarize the surface masses obtained for the various formulations. Let's remember that :

• The hooking strategy I according to FR 2984343 A1 is carried out with the addition of succinic acid and sodium hypophosphite;
• One-step attachment strategy II is direct attachment with the siliceous precursors used;

<b> Table 1 </b> Strategy I Sol-gel precursors Formulas Activated carbon concentration (g / l) Sol-gel reaction time before deposition Sol-gel deposit with activated carbon (g / m ² ) on fabric A (Averages) TMOS A ₁ 40.2 65h 29 TMOS A ₂ 99.8 24h 37 TMOS / MTM B 40.0 6 days 22 TMOS / APTES C ₁ 40.0 6h 27 TMOS / APTES C ₂ 100.0 25h 36 TMOS / APTES D ₁ 40.0 2h 27 TMOS / APTES D ₂ 100.0 2h 42 1h45 37 (Fabric B) 1h45 435 (Fabric C) TMOS / APTES / 17FTMOS E ₁ 40.0 5h 30 TMOS / APTES / 17FTMOS E ₂ 100.1 4:30 p.m. 44 TMOS / APTES / 17FTMOS F ₁ 40.0 1h 31 TMOS / APTES / 17FTMOS F ₂ 100.2 2h20 40 Strategy II Sol-gel precursors Formula Activated carbon concentration (g / l) Sol-gel reaction time before deposition Sol-gel deposit with activated carbon (g / m ² ) on fabric A (Averages) TMOS At ₁ ' 40.0 14 days 21 TMOS At ₂ ' 100.0 28 days 36 TMOS / APTES D ₁ ' 40.0 1 min 28 TMOS / APTES D ₂ ' 100.0 35 mins 33 TMOS / APTES / 17FTMOS E ₁ ' 40.1 5 minutes 17 TMOS / APTES / 17FTMOS E ₂ ' 100.0 10 days 35 TMOS / PhTMOS G ₁ ' 10.0 3 days 18 TMOS / PhTMOS G ₂ ' 20.0 10 days 19 TMOS / PhTMOS H ₁ ' 20.0 3 days 20 TMOS / PhTMOS H ₂ ' 40.0 21 days 26

Example 2: Properties of the impregnated fabrics of Example 1 ▪ Scanning Electron Microscopy

In order to demonstrate the fact that the activated carbon is bound to the textile thanks to the presence of sol-gel, the textiles were characterized by SEM before and after impregnation with the solutions.

Scanning Electron Microscopy (SEM) is a powerful technique for observing surface topography. It is based mainly on the detection of secondary electrons emerging from the surface under the impact of a very fine primary electron brush which scans the observed surface and makes it possible to obtain images with a resolving power often less than 5 nm and great depth of field. The instrument makes it possible to form an almost parallel, very thin (down to a few nanometers) brush of electrons strongly accelerated by adjustable voltages of 0.1 to 30 keV, to focus it on the area to be examined and to sweep it gradually. Appropriate detectors collect significant signals while scanning the surface and form various ones meaningful images. Images of tissue samples were taken with Zeiss "Ultra 55" SEM. The samples are observed directly without any particular deposit (metal, carbon). A low acceleration voltage of 3 keV and the InLens detector (backscattered and secondary electron detector) allow the samples to be observed and avoid an excessive charge phenomenon due to the nature of the tissues.

The three fabrics A, B and C (fabric A: fabric in Kermel® / Lenzing 50: 50; fabric B: fabric in Conex® / Lenzing 50: 50; fabric C: felt in Nomex®) were observed before impregnation, without carry out no special preparation. The SEM images show that these three textiles have relatively smooth fibers ( Figures 1 to 3 ), with some roughness / grooves in the case of both fabrics ( Figures 2 and 3 ).

The samples of fabrics A impregnated with formulations D ₁ , D ₂ , D ₁ 'and D ₂ ' (Example 1) were also observed by SEM. For formulations D ₁ and D ₂ prepared according to strategy I, the SEM images show that the sol-gel coats the activated carbon particles and fixes them on the fibers, forming a continuous sheath ( Figures 4 and 5 ). The SEM images of the tissues impregnated with formulations D1 'and D2' prepared according to strategy II ( Figures 6 and 7 ) show that the deposits are similar to those obtained with the solutions of strategy I. For the fabric impregnated with formulation D ₁ ', it is in fact observed that the sol-gel, which is thicker and fractured, coats the particles of activated carbon and fixes them on the fibers forming a sheath.

The SEM images of samples of fabrics B and C impregnated with formulation D ₂ (Example 1) also show that the sol-gel coats the particles of activated carbon and fixes them on the fibers forming a continuous sheath ( Figures 8 and 9 ). The particles are more spaced apart in the case of felt while clusters are visible in the case of open Conex® / Lenzing fabric (fabric B).

▪ Air permeability

With a view to the intended applications, in particular in filtration, it is essential that the textiles be sufficiently permeable to air and / or to liquids. The air permeability of the textiles was therefore measured before and after deposition, following the ISO 9237: 1995 standard at 100 Pa. The results of the measurements are presented in Table 3. <b> Table 3 </b> Textiles Formula filed Sol-gel deposit with activated carbon (g / m ² ) Air permeability under 100 Pa (l / m ² .s) Before deposit After deposit Fabric A D ₂ 42 139 22 Fabric B D ₂ 37 1032 122 Fabric C D ₂ 435 745 182

For fabrics B and C, the air permeability is lowered after deposition but remains suitable. On the other hand, the structure of the impregnated textile plays a predominant role in the permeability since, for the same formula deposited, the fabric C (felt) is eight times more permeable than the fabric A (Kermel® / Lenzing fabric). , yet with a deposit ten times larger.

▪ Visual aspect

The sol-gel deposit with activated carbon is uniform and changes the appearance of textiles, whatever their structure ( Figures 10, 11, 12 , 13 ). The sol-gel formula has no impact on the visual appearance of textiles after deposition, unlike its activated carbon content: the higher the concentration, the more the color will tend towards black.

▪ Flexibility

The flexibility of the textiles before / after deposition is evaluated by measuring the drop angle.

The flexibility of the textiles before / after impregnation was evaluated with the flexibility measurement tool shown in Figure 14A . This tool 1 consists of two parts, a lower part 2 serving as a support for the fabric T and an upper part 3 which fits on the lower part to block the fabric T. The Figure 14B shows the block diagram for the measurement. To make a measurement 5 cm of fabric are positioned "in the void", that is to say outside the measuring tool, a photo is taken in profile, then, on the profile photo, the The angle α formed between the fabric and the vertical is measured using a protractor to assess the drop off of the fabric.

This tool allows a comparison of samples with a reference (tissue without sol-gel) as shown in the photos shown in figure 15 .

Tables 3 and 4 below summarize the flexibility measures before / after deposition of sol-gel. <b> Table 4 </b> Strategy I Textiles Formula filed Sol-gel deposit with activated carbon (g / m ² ) Mean angle measured (°) Fabric A - - 18 A ₁ 29 83 A ₂ 37 81 B 22 82 C ₁ 27 81 C ₂ 36 81 D ₁ 27 70 D ₂ 42 72 E ₁ 30 77 E ₂ 44 78 F ₁ 31 65 F ₂ 40 70 Fabric B - - 11 D ₂ 37 79 Fabric C - - 69 D ₂ 435 90 Strategy II Textiles Formula filed Sol-gel deposit with activated carbon (g / m ² ) Mean angle measured (°) Fabric A - - 18 At ₁ ' 21 70 At ₂ ' 36 50 D ₁ ' 28 67 D ₂ ' 33 81 E ₁ ' 17 69 E ₂ ' 35 69 G ₁ ' 18 74 G ₂ ' 19 64 H ₁ ' 20 69 H ₂ ' 26 73

As expected, textiles are more rigid after deposition. These measurements also show that the flexibility of textiles can vary with the sol-gel formulas (precursors) and their activated carbon concentration. On the other hand, textiles impregnated with formulations according to strategy II are generally more flexible than those impregnated with formulations according to strategy I.

▪ Hydrophobia

The precursors used for the formation of the sol-gel can be chosen in order to provide water-repellency properties. Thus, formulations containing fluorinated precursors (such as formulas E ₁ , F ₁ , F ₂ and E ' ₁ make it possible to obtain hydrophobic fabrics. The hydrophobic properties of fabrics impregnated with formulations E ₁ , E ₂ , F ₁ , F ₂ , E ' ₁ and E' ₂ were determined by contact angle measurements with the “OCA 15EC” goniometer from DataPhysics and the “SCA20” software in dynamic mode with the acquisition of 4 measurements per second for 1 min in order to to determine the stability of the water drop (10µL) on the tissue Table 7 below summarizes the average contact angles over 2 or 3 measurements at t0. <b> Table 6 </b> Textile Formula filed Hydrophobic Contact angle (°) Fabric A - No 0 E ₁ Yes 150 ± 5 E ₂ No 0 F ₁ Yes 165 ± 5 F ₂ Yes 140 ± 5 E ₁ ' Yes 150 ± 5 E ₂ ' No 0

Example 3: Gas phase filtration

Fabrics impregnated with each sol-gel formulation were exposed to gas mixtures containing methyl salicylate or toluene to test the trapping efficiency as a function of the porosity properties of the sol-gel materials and the intrapore polarity. The drilling curves under gas flow were established for each pollutant.

3.1 Materials and methods Gas permeability of tissue

In order to test the permeability of tissues to gases, a test bench was installed in the laboratory. For this, a “Porometer 3G, sample holder 37 mm” porometer from Quantachrome was used. This porometer makes it possible to test a tissue with a diameter of 37 mm (cutout carried out with a punch). Sealing is ensured by O-rings. Thus, the gas flow passes through all of the tissue being tested.

• ▪ Test de perméabilité au toluène : Pour les tests d'exposition au toluène, ce polluant est obtenu à partir d'une bouteille calibrée à 100 ppm (le débitmètre utilisé est dans la gamme : 0-100 mL/min) puis dilué dans l'azote sec (le débitmètre utilisé est dans la gamme : 0-1 L/min). Le flux de gaz dilué est mis en contact avec le tissu testé. Une teneur initiale en toluène de 3-4 ppm est utilisée pour les tests de perméabilité.
• ▪ Test de perméabilité au salicylate de méthyle : Pour les tests d'exposition au salicylate de méthyle, les vapeurs de ce polluant sont générées par bullage d'azote sec (le débitmètre utilisé est dans la gamme : 0-1 L/min). Le flux de gaz enrichi en salicylate de méthyle est mis en contact avec le tissu testé. Un thermostat/cryostat pour réguler la température du bulleur contenant le salicylate de méthyle (serpentin) est utilisé afin d'assurer la reproductibilité des tests d'exposition. Le bulleur contenant le salicylate de méthyle est ainsi régulé à 20°C. En utilisant un débit d'azote sec de 300 mL/min, une teneur initiale de 55-60 ppm en salicylate de méthyle est obtenue.

The tissue test bench consists of two 4-way valves upstream and downstream of the sample holder allowing the measurement of gas flows on either side of the sample holder. The tests have shown that there is no (or little) pressure drop in the presence of the tissue tested. The pollutant contents are measured in the gas flow after the sample holder using a PID detector (PhotoIonization Detector) in order to obtain the pollutant piercing curve. Tissue permeability is tested using two pollutants: toluene and methyl salicylate. Each pollutant has its own mode of exposure. These modes are described below.

• ▪ Toluene permeability test: For toluene exposure tests, this pollutant is obtained from a bottle calibrated at 100 ppm (the flowmeter used is in the range: 0-100 mL / min) then diluted in l dry nitrogen (the flowmeter used is in the range: 0-1 L / min). The diluted gas stream is contacted with the tissue being tested. An initial toluene content of 3-4 ppm is used for permeability tests.
• ▪ Methyl salicylate permeability test : For the methyl salicylate exposure tests, the vapors of this pollutant are generated by bubbling dry nitrogen (the flowmeter used is in the range: 0-1 L / min). The gas stream enriched in methyl salicylate is brought into contact with the tissue tested. A thermostat / cryostat to regulate the temperature of the bubbler containing the methyl salicylate (coil) is used to ensure the reproducibility of the exposure tests. The bubbler containing the methyl salicylate is thus regulated at 20 ° C. Using a dry nitrogen flow rate of 300 mL / min, an initial methyl salicylate content of 55-60 ppm is obtained.

Methods of Exploitation of Methyl Salicylate Permeability Data

Methyl salicylate permeability tests consist of measuring the salicylate content (in ppm) as a function of time. This path is called a drilling curve whose shape in "S" is more or less marked. The comparison of the standardized methyl salicylate piercing curves with a deposit of 20 g / m ² for the initial tissue, formula D ₂ (strategy I) and formula D ' ₂ (strategy II) is presented in Figure 16 .

The drilling curves obtained were used by two methods: decomposition of the drilling curve and modeling of the drilling curve. Both methods are detailed below.

▪ Method 1: Decomposition of the drilling curve

The first method to assess filtration is to break down the piercing curve and analyze the total trapping times. The total trapping times are determined for a methyl salicylate content at 0 ppm (t @ 0 ppm), a methyl salicylate content of less than 1 ppm (t <1 ppm), less than 5 ppm (t <5 ppm) ) and less than 20 ppm (t <20 ppm). These total trapping times constitute the characteristic times of the decomposition method.

▪ Method 2: Modeling of the drilling curve

The second method for evaluating the filtration consists in modeling the borehole curve by a sigmoid function according to the Hill model described below. This model was chosen because, by definition, it allows modeling from point (0,0), that is to say: a salicylate content of 0 ppm at t = 0 min. This model, resulting from enzymatic catalysis, models strictly positive data following a sigmoid (“S” -shaped curve) which corresponds well to the piercing curves obtained by exposure of tissues impregnated with sol-gel to methyl salicylate.

The characteristic time of the drilling curve modeling method is therefore: t _1/2 . In addition, from the parameters of the model, the slope of the curve can be calculated. For this, two points are necessary: A (t _A ; T _A ) and B (t _B ; T _B ). The calculation of the coordinates and the slope are recalled in the table below.

▪ Data comparison: normalization of characteristic times

The surface masses of the sol-gel deposits vary between 15 and 30 g / m ² . However, the comparison of data is only possible with identical mass. Thus, to overcome mass differences surface, the characteristic times of the two methods described above were normalized to an average deposit of 20 g / m ² . In practice, the normalization is calculated as follows: $$\left|\mathit{t}\left(\mathit{min}\right)\right|=\frac{t_{\mathrm{vs}\mathrm{To}r\mathrm{To}\mathrm{vs}t\mathrm{é}\mathit{ristic}}\left(\mathit{min}\right)}{\mathit{Mass}\mathit{surface}exp\mathrm{é}\mathit{rhyme}\left(g/{\mathrm{<figure-callout\; id="2"\; label="m"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">m</figure-callout>}}^2\right)}\times \mathit{Mass}\mathit{surface}\mathit{of}20g/{\mathrm{<figure-callout\; id="2"\; label="m"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">m</figure-callout>}}^2$$

In this way, the data are reported at the same weight: the comparison of the formulas is therefore possible.

3.2 results ▪ Exposure to methyl salicylate

The results of attachment strategies I and II are reported in Tables 7 and 8 below for the efficiency of trapping methyl salicylate. <b> Table 7 </b> Strategy I Time (min) | t _{@ 0 ppm} | | t _{<1 ppm} | | t _{<5 ppm} | | t _{<20 ppm} | | t _1/2 | Slope (ppm / min) Fabric A without deposit 0.0 1.0 1.5 3.0 4.2 6.42 Formula A ₁ 16.2 25.0 32.4 42.2 52.6 1.68 A ₂ 6.92 19.0 27.7 38.5 58.1 1.47 B - 1.07 2.88 7.5 11.5 1.93 C ₁ - 11.3 17.4 23.4 31.6 3.32 C ₂ - 18.3 24.9 33.8 50.5 2.02 D ₁ - 11.2 17.9 25.4 36.5 2.61 D ₂ 16.1 37.1 51.7 76.1 101.8 0.56 E ₁ 7.12 14.4 19.6 27.8 33.5 2.25 E ₂ 17.0 22.5 29.3 38.6 51.4 1.71 F1 13.6 19.1 21.2 36.9 40.9 1.17 F ₂ 10.8 19.6 23.5 30.8 42.3 1.90 Fabric B without deposit 0.00 1.13 1.65 3.68 4.7 4.72 Formula D ₂ 0.00 15.3 36.1 68.6 95.4 0.53 Fabric C without deposit 0.00 0.83 1.80 2.50 3.7 6.77 Formula D ₂ 13.0 17.2 22.0 35.0 58.9 3.09 Strategy II Time (min) | t _{@ 0 ppm} l | t _{<1 ppm} | | t _{<5 ppm} | | t _{<20 ppm} | | t _1/2 | Slope (ppm / min) Fabric A without deposit 0.0 1.0 1.5 3.0 4.2 6.42 Formula D ₁ ' 45.6 53.2 64.9 84.7 99.4 0.81 D ₂ ' - 53.9 76.6 112 134.6 0.58 E ₁ ' - 17.4 22.5 31.1 39.1 1.36 E ₂ ' - 54.9 71.3 92.0 106.8 0.87 G ₁ ' - 21.6 31.6 44.1 49.5 1.19

The results obtained in filtration of methyl salicylate show that the textiles are much more efficient after deposition. On the other hand, all of the formulations tested according to the bonding strategy II exhibit better filtration performance than the formulations prepared according to the bonding strategy I based on the same sol-gel precursors. These results clearly demonstrate that the incorporation of the polycarboxylic acid and of the catalyst modify the sol-gel making it unsuitable for an application in gas filtration. Likewise, the filtration performance for the same formulation is higher when the activated carbon concentration is higher.

The best methyl salicylate permeability result is obtained with formulation D ₂ 'according to strategy II. However, considering the results obtained with formulation G ₁ ′, it is expected that the same formulation containing ten times more activated carbon (100 g / l) will make it possible to obtain a better result.

Furthermore, successive deposits were tested to increase the surface weight of the filter material. From 1 to 3 successive deposits of formula A1 were made. These led to surface masses of between 24 and 90 g / m ² . Methyl salicylate scavenging efficiency results are shown in Table 9 below. <b> Table 9 </b> Successive deposits with strategy I Formula Number of deposits Mass per unit area (g / m ² ) t _1/2 (min) Slope (ppm / min) Initial fabric 0 0 4.2 6.4 A1 1 24 98.6 1.2 3 90 180.8 0.8

▪ Exposure to toluene

As with methyl salicylate, the toluene permeability tests consist of measuring the toluene content (in ppm) as a function of time. This path is called a drilling curve whose shape in "S" is more or less marked. The comparison of the normalized toluene piercing curves with a deposit of 20 g / m ² for the initial tissue, formula D ₂ (strategy I) and formula D ' ₂ (strategy II) is presented in Figure 16 .

The data processing methods are the same as for methyl salicylate. The attachment strategies I and II are compared in Tables 10 and 11 below for the efficiency of trapping toluene. <b> Table 10 </b> Strategy I Time (min) | t _{@ 0 ppm} | | t _{<1 ppm} | | t _{<2 ppm} | | t _{<3 ppm} | Fabric A without deposit 0.0 0.2 0.3 0.4 Formula A ₁ 17.5 44.1 78.3 161 A ₂ 30.8 93.8 145 - B 0.14 0.27 4.65 55.8 C ₁ 0.94 43.0 66.0 104 C ₂ 21.1 76.7 111 163 D ₁ 18.7 48.5 76.9 136 D ₂ 35.3 104 160 - E ₁ 4.85 19.4 33.0 64.1 E ₂ 11.3 42.8 67.6 131 F ₁ 4.21 21.4 37.5 74.4 F ₂ 34.2 54.8 86.6 - Fabric C without deposit 0.00 0.27 0.82 26.0 Formula D ₂ 52.0 73.9 - - Strategy II Time (min) | t _{@ 0 ppm} | | t _{<1 ppm} | | t _{<2 ppm} | | t _{<3 ppm} | Fabric A without deposit 0.0 0.2 0.3 0.4 Formula D ₁ ' 35.6 79.4 112 174 D ₂ ' - 111 161 237 E ₁ ' - 29.3 46.8 74.7 E ₂ ' - 110 150 206 G ₁ ' - 29.6 53.0 87.9

The results obtained for permeability to toluene follow the same trends as those obtained for permeability to methyl salicylate. In fact, the filtration performance of toluene is also superior with the attachment strategy II, as well as with a higher concentration of activated carbon.

The best toluene permeability results are obtained with formulation D ' ₂ , which also gave the best performance for methyl salicylate.

Example 4: Porosity of sol-gel materials with activated carbon

The porosity of sol-gel materials was determined from the establishment of nitrogen adsorption isotherms (specific surface area, pore volume, pore size distribution). The intrapore polarity is revealed by the material's ability to more effectively trap methyl salicylate compared to toluene.

4.1 Materials and methods

Nitrogen adsorption consists of the physisorption of nitrogen at the surface of a solid: this is a reversible phenomenon (adsorption / desorption). Nitrogen adsorption a volumetric technique: a volume of gas of known temperature and pressure is sent to the previously degassed sample and maintained at the temperature of liquid nitrogen. An adsorption isotherm corresponding to the volume of adsorbed gas as a function of the partial pressure of nitrogen is established. The interpretation of adsorption isotherms is carried out based on various analytical models: Brunauer, Emmett and Teller (BET) model which is an adsorption model of a monomolecular layer of nitrogen molecules in the pores, and model based on the density functional theory (DFT) which reproduces with the help of Monte Carlo methods the adsorption isotherm for pores of given size. These analyzes provide three pieces of information: the specific adsorption surface area, the pore volume and the pore size distribution. The analyzes were carried out with the “AUTOSORB-1” porosity analyzer from Quantachrome.

4.1 Results

The table below summarizes the polarity and porosity of sol-gel materials with activated carbon in the form of monoliths, obtained by BET analysis with nitrogen adsorption (specific adsorption surface area, pore volume, pore size distribution). <b> Table 12 </b> Formula Specific surface (m ² / g) Pore volume (cm ³ / g) Micro-, meso-, macropore pore size distribution (%) S _BET S _DFT <20 Å 20-500 Å > 500 Å Strategy I A ₂ 880 ± 80 810 ± 70 0.52 ± 0.01 56.5 44.5 0.0 D ₁ 710 ± 50 680 ± 50 0.60 ± 0.02 51.5 49.5 0.0 D ₂ 940 ± 80 940 ± 80 0.80 ± 0.05 53.9 47.1 0.0 E ₂ 710 ± 50 690 ± 60 0.58 ± 0.02 72.0 28.0 0.0 Strategy II D ₁ ' 760 ± 60 740 ± 60 52.7 47.3 0.0 D ₂ ' 940 ± 80 900 ± 80 0.85 ± 0.05 48.5 51.5 0.0 E ₂ ' 910 ± 80 900 ± 80 0.74 ± 0.04 63.9 37.1 0.0

These results show above all that the composite material described in the invention (sol-gel with activated carbon) does indeed exhibit significant porosity, the presence of the sol-gel therefore not obstructing the pores of the activated carbon. In addition, and as expected, a higher concentration of activated carbon in the same sol-gel formulation results in a higher specific adsorption surface area and a higher pore volume. Finally, the sol-gel formulations according to strategy II have a greater porosity (specific adsorption surface area and pore volume) than those according to strategy I. For filtration applications, strategy II again appears to be the most suitable.

Claims (23)

1. A process for coating a textile material, said process comprising the following steps:

   a) incorporating active charcoal in powder form into a coating composition comprising an aqueous solvent and at least one organosilicon precursor, in which the organosilicon precursor represents 5% to 50% by volume relative to the combination of aqueous solvent and organosilicon precursor,

   b) impregnating the textile material by padding with the coating composition, and

   c) drying the impregnated textile material,

   characterized in that the coating composition is free of polycarboxylic acid and of catalyst.
2. The process as claimed in claim 1, characterized in that the coating composition is also free of surfactant.
3. The process as claimed in claim 1, characterized in that the textile material is a fabric, a nonwoven or a knit, preferably a fabric or a nonwoven.
4. The process as claimed in any one of the preceding claims, characterized in that the textile material comprises fibers including hydrolyzable functions, such as hydroxyl functions.
5. The process as claimed in any one of the preceding claims, characterized in that the aqueous solvent is water or a mixture of water and of an organic solvent.
6. The process as claimed in any one of the preceding claims, characterized in that the organosilicon precursor is chosen from tetramethoxysilane (TMOS), tetraethoxysilane (TEOS), methyltrimethoxysilane (MTM), methyltriethoxysilane (MTE), phenyltrimethoxysilane (PhTMOS), phenyltriethoxysilane (PhTEOS), a fluoroalkyltrimethoxysilane, a fluoroalkyltriethoxysilane, a chloroalkylmethoxysilane, a chloroalkylethoxysilane, an aminopropyltriethoxysilane, (3-glycidyloxypropyl)trimethoxysilane (GPTMOS) and mixtures thereof, preferably from tetramethoxysilane (TMOS), methyltrimethoxysilane (MTM), phenyltrimethoxysilane (PhTMOS), a fluoroalkyltrimethoxysilane, a chloroalkylmethoxysilane, an aminopropyltriethoxysilane, (3-glycidyloxypropyl)trimethoxysilane (GPTMOS), and mixtures thereof.
7. The process as claimed in claim 6, characterized in that the organosilicon precursor is tetramethoxysilane (TMOS).
8. The process as claimed in claim 6, characterized in that the organosilicon precursor is a mixture of tetramethoxysilane (TMOS) with one or more precursors chosen from methyl trimethoxysilane (MTM), methyl triethoxysilane (MTE), phenyltrimethoxysilane (PhTMOS), phenyltriethoxysilane (PhTEOS), a fluoroalkyltrimethoxysilane, a fluoroalkyltriethoxysilane, a chloroalkylmethoxysilane, a chloroalkylethoxysilane, an aminopropyltriethoxysilane, (3-glycidyloxypropyl)trimethoxysilane (GPTMOS), and mixtures thereof.
9. The process as claimed in claim 8, characterized in that the organosilicon precursor is a mixture of tetramethoxysilane (TMOS) with aminopropyl triethoxysilane (APTES).
10. The process as claimed in any one of the preceding claims, characterized in that it includes several successive cycles of impregnation by padding.
11. The process as claimed in any one of the preceding claims, characterized in that it comprises, before step b), a step of applying a precoating composition comprising an organic solvent and a zirconium alkoxide, said precoating composition being free of polycarboxylic acid.
12. A coating composition comprising an aqueous solvent, an organosilicon precursor and active charcoal in powder form, characterized in that the organosilicon precursor represents 5% to 50% by volume relative to the combination of aqueous solvent and organosilicon precursor, said composition being free of polycarboxylic acid and of catalyst.
13. The composition as claimed in claim 12, characterized in that the aqueous solvent is water or a mixture of water and of an organic solvent.
14. The composition as claimed in claim 12 or 13, characterized in that the organosilicon precursor is chosen from tetramethoxysilane (TMOS), tetraethoxysilane (TEOS), methyltrimethoxysilane (MTM), methyltriethoxysilane (MTE), phenyltrimethoxysilane (PhTMOS), phenyltriethoxysilane (PhTEOS), a fluoroalkyltrimethoxysilane, a fluoroalkyltriethoxysilane, a chloroalkylmethoxysilane, a chloroalkylethoxysilane, an aminopropyltriethoxysilane, (3-glycidyloxypropyl)trimethoxysilane (GPTMOS) and mixtures thereof, preferably from tetramethoxysilane (TMOS), methyltrimethoxysilane (MTM), phenyltrimethoxysilane (PhTMOS), a fluoroalkyltrimethoxysilane, a chloroalkylmethoxysilane, an aminopropyltriethoxysilane, (3-glycidyloxypropyl)trimethoxysilane (GPTMOS), and mixtures thereof.
15. The composition as claimed in claim 14, characterized in that the organosilicon precursor is tetramethoxysilane (TMOS).
16. The composition as claimed in claim 14, characterized in that the organosilicon precursor is a mixture of tetramethoxysilane (TMOS) with a precursor chosen from methyl trimethoxysilane (MTM), methyl triethoxysilane (MTE), phenyltrimethoxysilane (PhTMOS), phenyltriethoxysilane (PhTEOS), a fluoroalkyltrimethoxysilane, a fluoroalkyltriethoxysilane, a chloroalkylmethoxysilane, a chloroalkylethoxysilane, an aminopropyltriethoxysilane, (3-glycidyloxypropyl)trimethoxysilane (GPTMOS), and mixtures thereof.
17. The composition as claimed in claim 16, characterized in that the organosilicon precursor is a mixture of tetramethoxysilane (TMOS) with aminopropyl triethoxysilane (APTES).
18. An impregnated textile material obtained according to the coating process as claimed in any one of claims 1 to 11.
19. A textile material impregnated with a coating composition as claimed in any one of claims 12 to 17.
20. The textile material as claimed in claim 18 or 19, characterized in that it has a specific surface area S_BET, determined from adsorption isotherms using the Brunauer-Emmet-Teller (BET) model, of between 580 ± 50 and 950 ± 80 m².g^-1, notably between 800 ± 70 and 950 ± 80 m².g^-1.
21. A gas filter comprising the impregnated textile material as claimed in any one of claims 18 to 20.
22. Personal protection equipment comprising the impregnated textile material as claimed in any one of claims 18 to 20.
23. The personal protection equipment as claimed in claim 22, characterized in that it is NBC personal protection equipment.

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