Textile bonded by a binder based on polyelectrolytes having opposite charge polarities

Abstract

The present invention relates to a textile comprising textile fibers and a non-aqueous, non-crosslinked polymeric binder, said polymeric binder comprising a solid polyelectrolyte complex consisting of an anionic polyelectrolyte and a cationic polyelectrolyte. The invention also relates to a process for manufacturing such a textile and to a method for recycling such a textile.

Description

[0001] Textile bound by a binder based on polyelectrolytes with opposite charge polarities

[0002] The present invention relates to textiles comprising textile fibers, organic or mineral, bound by a non-crosslinked, water-insoluble binder formed by a complex of oppositely charged polyelectrolytes. It also relates to a method of manufacturing such textiles and a method of recycling such textiles by solubilizing the binder in an aqueous saline solution and reusing the fibers.

[0003] The construction industry continues to demand low-cost materials that are free of volatile organic compounds and recyclable.

[0004] In the field of non-woven mats intended for construction, the fibres are generally held together by a thermoset, crosslinked binder based on phenol-formaldehyde, melamine-formaldehyde or urea-formaldehyde resins or based on crosslinked organic polymers, for example acrylic polymers.

[0005] Woven or knitted textiles, especially when made from glass textile fibers, are also often coated with thermoset binders.

[0006] The production of such textiles bound by insoluble crosslinked binders generally implies the impossibility of recycling production waste, such as offcuts cut from the edges of rolls, rolls with manufacturing defects or roll offcuts generated following cutting during the transformation of nonwovens.

[0007] In the field of mineral wool insulation products, which generally contain between 5% and 10% organic binder by weight, such production waste can be recycled by re-introducing it into the manufacturing process upstream of the melting stage. However, such recycling by re-melting production waste is problematic, if not impossible, when the binder content exceeds 15 or 20% by weight of the material, as is typically the case with non-woven mats intended for construction.

[0008] The aim of this application is to propose a binder for the manufacture of textiles based on organic and / or mineral textile fibres, which allows recycling of production waste, without melting or combustion / pyrolysis, and reuse of the fibres and possibly the binder for the manufacture of other textiles, in particular non-woven mats.

[0009] The present invention is based on the idea of ​​using adhesives based on polyelectrolytes with opposite charge polarities, known for several years in the medical and biomedical field under the name of polyelectrolyte complexes / coacervates (PEC) (WO201 1 / 149907A1, WO2011 / 106595, WO2012 / 065148, WO2016 / 011028, WO2019 / 172764), to reversibly bond textile fibers, in particular nonwoven mats.

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

[0011] The rapid transition of viscous polyelectrolyte coacervates into solid polyelectrolyte complexes upon contact with water allows for efficient solidification and immediate setting of the composition at room temperature, without the need for chemical curing agents or energy input. This solidification is reversible because the solid polyelectrolyte complexes can be easily "dissolved" simply by contact with high ionic strength aqueous solutions.

[0012] In the present invention, the solidification / liquefaction behavior of such oppositely charged polyelectrolyte systems is used to manufacture textiles from textile, mineral and / or organic fibers.

[0013] To do this, a layer of mineral or organic textile fibers is impregnated with a fluid coacervate of polyelectrolytes containing a polyanion and a polycation dissolved in salt water. This binder is then solidified in contact with the fibers by placing it in contact with water to eliminate the salt. The solidified binder is a polyelectrolyte complex which, although insoluble in water, is not crosslinked. The absence of crosslinking allows it to be fluidized again for the purpose of recycling the fibers.

[0014] In the following, the term "polyelectrolyte coacervate" will designate a fluid or viscous aqueous composition containing, dissolved in water, a polyanion, a polycation and a water-soluble mineral salt in a concentration sufficient to prevent the formation of a solid polyelectrolyte complex. The term "polyelectrolyte complex" will designate a solid material containing a polyanion and a polycation. The polyelectrolyte complex does not normally contain water or a water-soluble mineral salt, except in trace amounts.

[0015] The present application therefore relates to a textile comprising textile fibres and a non-crosslinked, water-insoluble polymer binder, said polymer binder comprising a solid polyelectrolyte complex formed of an anionic polyelectrolyte and a cationic polyelectrolyte.

[0016] The term "polyelectrolyte" refers to a polymer comprising or consisting of ionic monomers, i.e. carrying positive or negative charges.

[0017] The cationic polyelectrolyte (polycation) and the anionic polyelectrolyte (polyanion) are preferably present in similar amounts. Since the formation of a solid binder giving the textile (e.g. non-woven mat) satisfactory mechanical properties relies on the electrical attraction of the opposite charges of the polyelectrolytes, the respective amounts of the anionic and cationic polyelectrolytes are expressed in terms of amounts of charges. Thus, the respective amounts of the anionic and cationic polyelectrolytes are such that the ratio of the number of positive charges present on the cationic polyelectrolyte to the number of negative charges on the anionic polyelectrolyte is between 0.5 and 2, preferably between 0.6 and 1.8, in particular between 0.7 and 1.6, more preferably between 0.8 and 1.4, and ideally between 0.9 and 1.2.

[0018] The term "cationic polyelectrolyte" encompasses in the present application a single type of cationic polymer or a mixture of two or more different cationic polyelectrolytes and the term "anionic polyelectrolyte" encompasses a single type of anionic polymer or a mixture of two or more anionic polyelectrolytes. The polyelectrolytes may be strong or weak polyelectrolytes. A strong polyelectrolyte is a polymer whose net charge, positive or negative, is essentially independent of the pH of the composition. In particular, the zeta potential of a strong cationic polyelectrolyte is positive for any pH in the range of 1 to 14 and the zeta potential of a strong anionic polyelectrolyte is negative for any pH in the range of 1 to 14. The potential may be measured using a zeta potential analyzer (eg"zetasizer" device) at a suitable concentration (generally greater than 0.01%, for example 1% by weight of polyelectrolyte relative to the volume of solution analyzed) and generally at 20°C. Examples of strong cationic polyelectrolytes include polymers comprising a plurality of quaternized amine groups. Strong anionic polyelectrolytes are, for example, polymers comprising a multitude of sulfonate (-SO3) groups. Poly(acrylic acid) is an example of a weak anionic polyelectrolyte and non-quaternized polyamines are examples of weak cationic polyelectrolytes, since the net charge of these polymers depends on the pH of the solution.

[0019] Preferably, at least one of said anionic polyelectrolyte and said cationic polyelectrolyte is a strong polyelectrolyte.

[0020] In some embodiments, the anionic polyelectrolyte and the cationic polyelectrolyte are both strong polyelectrolytes.

[0021] In the present application, an anionic polyelectrolyte is a polymer having, at pH 7, a negative net charge and a cationic polyelectrolyte is a polymer having, at pH 7, a positive net charge. This does not mean that an anionic polyelectrolyte comprises only negative charges and is free of positive charges. By analogy, cationic polyelectrolytes can carry both positive and negative charges as long as at pH 7 the overall net charge is positive.

[0022] Therefore, the definition of anionic polyelectrolytes encompasses zwitterionic polyelectrolytes having an isoelectric point (pI) < 7, preferably < 6, and the definition of cationic polyelectrolytes encompasses zwitterionic polyelectrolytes having an isoelectric point > 7, preferably > 8. The most well-known zwitterionic polyelectrolytes are proteins or polypeptides comprising both carboxylate (-COO) side groups and amino (-NH2) side groups.

[0023] In a preferred embodiment of the textile (e.g., being a nonwoven mat) of the present invention, the anionic polyelectrolyte comprises only negative charges and is free of positive charges and the cationic polyelectrolyte comprises only positive charges and is free of negative charges.

[0024] The cationic groups of the cationic polyelectrolyte are, for example, primary amine, secondary amine, tertiary amine or quaternized ammonium groups, located in the main chain of the polymer or on the side groups.

[0025] The cationic polyelectrolyte is preferably selected from the group consisting of

[0026] - poly(diallyldimethylammonium chloride),

[0027] - poly(2-hydroxypropyl)dimethylammonium chloride],

[0028] - polyamidoamine-epichlorohydrin (PAAE),

[0029] - polyethyleneimine,

[0030] - poly(acrylamide-co-diallyldimethylammonium chloride),

[0031] - copolymer of hydroxyethylcellulose and poly(diallyldimethylammonium chloride) (Polyquaternium-4),

[0032] - copolymer of acrylamide and dimethylaminoethyl methacrylate quaternized with dimethyl sulfate (Polyquaternium-5, CAS 26006-22-4), - copolymer of dimethylaminomethyl methacrylate and alkyl methacrylate,

[0033] - chitosan,

[0034] - quaternized poly(N,N-(dimethylamino)ethyl methacrylate),

[0035] - guar hydroxypropyltrimonium chloride,

[0036] - poly(N,N-dimethyl-3,5-dimethylene piperidinium chloride),

[0037] - poly(vinylbenzyltrimethylammonium chloride),

[0038] - poly[3-(methacryloylamino)propyl-trimethylammonium chloride], poly([2-(methacryloloxy)ethyl]-trimethylammonium chloride),

[0039] - polyvinylamine (PVA),

[0040] - poly(N,N-dimethyl-3,5-dimethylene piperidinium chloride) (PDDPC),

[0041] - poly(vinylbenzyltrimethylammonium chloride) (PVBTAC),

[0042] - poly(allylamine chloride) (PAH), and

[0043] - 3-(methacryloylamino)propyltrimethylammonium polychloride] (PMAPTAC),

[0044] - cationic dextran.

[0045] The anionic groups of the anionic polyelectrolyte are, for example, selected from the group consisting of carboxyl, sulfonate, phosphonate, boronate, sulfate, borate and phoshate residues. They can be located in the main chain of the polymer or on the side groups.

[0046] In an advantageous embodiment, the anionic polyelectrolyte is selected from the group consisting of poly(acrylic acid), poly(acrylic acid-co-acrylamido), poly(sodium 4-styrenesulfonate), lignosulfonate, sodium humate, alginate, poly(sodium 2-acrylamido-2-methyl-1-propanesulfonate), hyaluronic acid, dextran sulfate and poly(sodium vinylsulfonate).

[0047] The anionic and cationic polyelectrolytes, as defined above, generally represent, together, from 50% to 100% by weight, preferably from 70% to 98% by weight, in particular from 80% to 95% by weight of the cured polymer binder (polyelectrolyte complex), the complementary part being formed in particular

[0048] - unremoved salt residues,

[0049] - any functional additives or fillers, or

[0050] - polyphenols and transition metals as described in detail below functioning as a binder strengthening system.

[0051] In a preferred embodiment, at least one of the polyelectrolytes is a linear polymer, the other polyelectrolyte, of opposite charge, being able to be linear or branched. In other words, the anionic polyelectrolyte and / or the cationic polyelectrolyte can be linear polymers, free of branches.

[0052] The anionic and cationic polyelectrolytes have a weight-average molecular mass (determined by light scattering) of between 1,000 and 2,000,000, preferably between 50,000 and 700,000 Da, in particular between 100,000 and 400,000 Da.

[0053] The weight average molecular mass of the anionic polyelectrolyte is advantageously similar to that of the cationic polyelectrolyte. More precisely, the ratio of the weight average molecular mass of the anionic polyelectrolyte to the weight average molecular mass of the cationic polyelectrolyte is preferably between 0.4 and 1.6, more particularly between 0.7 and 1.3 and ideally between 0.8 and 1.2.

[0054] In principle, any type of textile fibers can be used, whether natural, artificial or synthetic, organic or mineral. The textile fibers of the textile of the present invention are preferably chosen from glass textile fibers, synthetic polymer textile fibers, for example polyester or polyamide (preferably polyester), and natural textile fibers, preferably natural plant textile fibers such as linen, hemp, cotton, jute, nettle, sisal, coconut, raffia, abaca, broom. Of course, the textile may contain a mixture of such textile fibers of different natures.

[0055] In some embodiments, the textile fibers forming the textile comprise (preferably consist of) mineral fibers - especially glass fibers - and optionally organic fibers such as polyester fibers, cellulose fibers or polyamide fibers.

[0056] In some embodiments, the textile fibers forming the textile comprise (preferably consist of) mineral fibers - especially glass fibers - and optionally biodegradable organic fibers, such as polylactic acid (PLA) fibers, polyglycolic acid (PGA) fibers, poly(lactic-co-glycolic) acid (PLGA) fibers or cellulose fibers (eg Lyocell fibers).

[0057] The mineral fibers advantageously represent at least 50%, preferably at least 60%, or even at least 70%, or even at least 80%, in particular at least 90%, of the total weight of the textile fibers forming the textile.

[0058] In a preferred embodiment, the textile fibers forming the textile are glass fibers and / or polyester fibers, preferably glass fibers.

[0059] The textile may be a mat, or veil, of short fibers arranged randomly in the plane of the textile. The textile may also be a woven or knitted textile structure based on long fibers. It may also be a laid scrim made by superimposing several layers of fibers arranged parallel to each other within the same layer, the different superimposed layers being linked together by a binder which partially or completely coats the fibers. In a preferred embodiment, the textile of the present invention is a non-woven mat of short fibers arranged randomly in the plane of the textile. The length of the fibers is generally between 10 mm and 1000 mm, in particular between 15 and 700 mm.

[0060] The polyelectrolyte complex that binds the fibers of the textile of the present invention may be reinforced by a reinforcing system based on polyphenols and transition metals. Indeed, the mechanical performance of a textile (such as a nonwoven mat) is generally improved when small amounts of water-soluble polyphenol(s) are added to the coacervate of oppositely charged polyelectrolytes. The water-soluble polyphenol acts as a reinforcing agent and its effectiveness is further increased when it is combined with very small amounts of a transition metal. The mechanisms involved in this reinforcing effect are probably hydrogen bonds, possibly associated with ligand-metal coordination bonds. These two types of bonds are not covalent bonds and their existence or strength depends on environmental conditions such as pH and / or ionic strength.These reinforcing bonds can therefore be undone, which is important from the point of view of the reversibility of the hardening of the binder.

[0061] The solid polyelectrolyte complex binding the textile fibers of the textile, in particular of the nonwoven mat of the invention, may therefore additionally contain at least one water-soluble polyphenol comprising at least one polyhydroxylated aromatic ring.

[0062] The amount of water-soluble polyphenol(s) generally does not exceed 1% by weight relative to the aqueous binder composition used to impregnate the textile fibers. It is advantageously between 0.02% and 1.0%, preferably between 0.03% and 0.5%, more preferably between 0.04% and 0.1% by weight of the aqueous binder composition (polyelectrolyte coacervate). The hardened binder (polyelectrolyte complex) advantageously contains from 0.001% to 0.5% by weight, preferably from 0.01 to 0.25% by weight, and more particularly from 0.05 to 0.5% by weight of polyphenol(s).

[0063] The term polyphenol refers to an organic compound comprising at least one polyhydroxylated aromatic ring, i.e. bearing at least two hydroxyl groups (-OH) on the same cyclic structure. A water-soluble polyphenol is a polyphenol with a solubility in distilled water at 20°C of at least 100 g / L.

[0064] In a preferred embodiment, at least a portion of the polyphenols used comprise at least two, preferably at least three and more preferably at least four polyhydroxylated aromatic rings.

[0065] The polyhydroxylated aromatic rings are preferably selected from the group consisting of catechol, pyrogallol and tetrahydroxylated or pentahydroxylated aromatic rings.

[0066] In a particularly interesting embodiment, the polyphenol is tannic acid (CAS No. 1401-55-4) which has five trihydroxylated aromatic ring structures. It is a relatively inexpensive, bio-sourced ingredient with a high concentration of polyhydroxylated aromatic rings.

[0067] More recently, synthetic organic polymers made from monomers with polyhydroxylated aromatic rings have been described (see for example the work of Cheng et al. in Nature Communications, 13, article no. 1892 (2022)). They could very effectively reinforce the final binder of the textile of the present invention, in particular when it is a nonwoven mat.

[0068] Therefore, in another advantageous embodiment of the present invention, the polyphenol used as a reinforcing agent for the polyelectrolyte complex is a synthetic copolymer comprising comonomers with polyhydroxylated aromatic structures, preferably a copolymer of styrene and a comonomer selected from the group consisting of dihydroxystyrene, trihydroxystyrene, tetrahydroxystyrene and pentahydroxystyrene.

[0069] The mechanical performance of the textile, in particular the nonwoven mat, can be further improved by combining polyvalent transition metal ions with the polyphenol-reinforced polyelectrolyte complex. The solid polyelectrolyte complex forming the binder of the textile, in particular the nonwoven mat, of the present invention therefore advantageously further comprises at least one water-soluble salt of a transition metal, preferably a salt of iron, zinc, cobalt, copper or vanadium.

[0070] The water-soluble salt(s) of a transition metal may be present in a total amount of between 0.001 and 0.1%, preferably between 0.005 and 0.05%, these percentages being expressed relative to the polyelectrolyte coacervate composition used for the impregnation of textile fibers.

[0071] The weight ratio of transition metal salt to polyphenol(s) is typically between 0.1 and 0.2, preferably between 0.12 and 0.18.

[0072] Transition metals are preferably selected from the group consisting of iron (Fe), zinc (Zn), cobalt (Co), copper (Cu) and vanadium (V). Halides, particularly chlorides and bromides, are preferred anions of transition metal salts used, in association with polyphenols, to strengthen polyelectrolyte complexes.

[0073] The polyelectrolyte complex that binds the fibers of the textile of the present invention can be reinforced by adding a branched polymer. The branched polymer can for example be a polyethyleneimine (PEI). The weight-average molecular weight of the branched polymer is generally between 1,300 g / mol and 750,000 g / mol, in particular between 5,000 g / mol and 100,000 g / mol, preferably between 10,000 and 50,000 g / mol, or even between 20,000 and 30,000 g / mol. The branched polymer can be added in a content of 0.01 to 1% by weight, based on the aqueous binder composition used to impregnate the textile fibers.

[0074] The invention also relates to a method for manufacturing textiles based on textile fibers bound by a polyelectrolyte complex, as described above.

[0075] This process includes the following steps:

[0076] - production of a layer of textile fibers,

[0077] - impregnation of the layer of unbonded textile fibers with a polyelectrolyte coacervate composition containing an anionic polyelectrolyte, a cationic polyelectrolyte and a salt selected from the group consisting of alkali or alkaline earth metal halides, preferably alkali metal halides,

[0078] - if necessary, removal of excess polyelectrolyte coacervate composition,

[0079] - possibly partial or complete drying of the layer of textile fibers, impregnated with the polyelectrolyte coacervate composition,

[0080] - bringing the layer of textile fibers, impregnated with the polyelectrolyte coacervate composition, into contact with water so as to extract the salt from the polyelectrolyte coacervate composition and to convert the polyelectrolyte coacervate composition into a solid polyelectrolyte complex.

[0081] In the case of a nonwoven mat, the layer of textile fibers is a layer of unbonded fibers. The step of manufacturing the layer of unbonded textile fibers can be carried out according to processes known in the textile industry, whether by dry or wet process.

[0082] The manufacture of woven, knitted or scrim textile structures formed from several superimposed layers of long fibres parallel to each other can also be carried out using techniques and processes well known in the field of textile manufacturing.

[0083] The impregnation of the textile fiber layer with the polyelectrolyte coacervate composition can also be carried out by methods known and commonly used in the textile industry. Examples of such methods include immersion, spraying, roller application or curtain application.

[0084] If necessary, excess coacervate composition is then removed by a suitable method, e.g., scraping, squeezing, blowing, suction, etc.

[0085] The quantity of polymer binder in the final textile is advantageously between 10 and 40% by weight, preferably between 15 and 30% by weight relative to the total dry weight of the textile.

[0086] The polyelectrolyte coacervate composition can be prepared by dissolving each of the cationic and anionic polyelectrolytes separately in an aqueous solution of an inorganic salt of an alkali or alkaline earth metal, preferably a halide of an alkali or alkaline earth metal. The salt concentration of the aqueous solution is typically between 0.05 and 6 mol / L, preferably between 0.2 and 2.5 mol / L, and in particular between 0.5 and 2.0 mol / L. The higher the average molecular weight of the polyelectrolytes, the greater the ionic strength of the salt solution must be. Thus, for weight average masses below 100,000 Da, salt concentrations between 0.2 and 1 mol / L are generally sufficient. To dissolve polyelectrolytes with weight average masses greater than 400,000 for the formation of a polyelectrolyte coacervate, salinities greater than 1.8 mol / L are required.

[0087] The pH of the two polyelectrolyte saline solutions is advantageously acidic, preferably between 1 and 3, better between 1 and 2. After complete dissolution of the anionic and cationic polyelectrolytes, the two solutions are simply mixed with each other. A lower, dense, polymer-rich phase, called the "coacervate", then separates from an upper, polymer-depleted phase, called the "supernatant". The two phases can be easily separated from each other, possibly after centrifuging the mixture.

[0088] On an industrial scale, it is of course advantageous to reduce the volume fraction of the supernatant phase as much as possible. This can be achieved by increasing the polyelectrolyte concentration and the salt concentration (halide of an alkali or alkaline earth metal) of the two solutions before mixing. It is imperative to always remove the supernatant phase, otherwise the composition will not harden after removal of the salts.

[0089] The solids fraction (polyelectrolytes, salts and additives) of the coacervate composition is typically between 20% and 35% by weight, preferably between 25% and 30% by weight.

[0090] The salt concentration of the polyelectrolyte coacervate composition is advantageously between 10% and 50% by weight, preferably between 15% and 45% by weight.

[0091] The polyelectrolyte content of the polyelectrolyte coacervate composition is between 1% and 30% by weight, preferably between 3% and 20% by weight, in particular between 4% and 15% by weight.

[0092] When polyphenols are used to strengthen the polyelectrolyte complex, they are advantageously added to the cationic polyelectrolyte solution, either before or after dissolving the polyelectrolyte. Adding the polyphenols to the anionic polyelectrolyte solution often results in the undesirable formation of a gel. The polyphenols can be added as such or they can be dissolved beforehand in an aqueous solution of the inorganic salt of an alkali or alkaline earth metal. When a water-soluble salt of a transition metal is also used, the latter is preferably added to the solution containing the cationic polyelectrolyte and the polyphenol.

[0093] The pH of the coacervate can then be adjusted to a value between 5 and 9, preferably between 6 and 8.

[0094] Various additives such as pigments, dyes, biocidal agents, cellulose fibres from the manufacture of paper pulp, fillers, anti-foaming agents, flame retardants, hydrophobic agents (e.g. silicone-based agents) may also be added to the coacervate in a maximum total quantity equal to 30% by weight, preferably 20% by weight and ideally 10% by weight, based on the weight of the polyelectrolytes and mineral salts of alkali or alkaline earth metal.

[0095] The final polyelectrolyte coacervate composition, when used to impregnate the textile fiber layer, preferably has a water content of between 15 and 80% by weight, particularly between 20 and 75% by weight and most preferably between 25 and 70% by weight.

[0096] After impregnation of the textile fiber layer with the coacervate composition, the mechanical strength of the impregnated textile fiber layer may be insufficient for the fiber layer to be immediately brought into contact with water in order to remove mineral salts (alkali or alkaline earth metal halides). This is particularly the case when the textile is a non-woven mat or veil or a canvas of several layers of superimposed fibers. It is then most often useful to subject the textile fiber layer impregnated with the coacervate to partial or complete drying. This drying can be done, for example, by passing the impregnated fiber layer through a ventilated and / or heated enclosure, or by exposing the impregnated fiber layer to infrared electromagnetic radiation or by contact with a heating cylinder (contact drying).This drying is generally not necessary when the textile is a woven fabric or a knitted textile.

[0097] The impregnated textile fiber layer, optionally partially or completely dried, is then brought into contact with water. Contacting may be achieved, for example, by sprinkling the impregnated textile fiber layer with water or by immersion in water. The water may be free of water-soluble salts or may contain water-soluble salts in a concentration significantly lower than that of the coacervate used for impregnating the textile fiber layer.

[0098] During this step of bringing the impregnated textile fiber layer into contact with water, the alkali or alkaline earth metal mineral salt is removed from the coacervate and the latter immediately solidifies to form a polyelectrolyte complex. This results in a textile of textile fibers bound by a solid binder based on oppositely charged polyelectrolytes.

[0099] As explained in the introduction to this application, the main advantage of using a polyelectrolyte coacervate to bind textile fibers is the reversibility of the binder hardening process. The binder based on a polyelectrolyte complex is, of course, solid at room temperature and insoluble in water, but it is soluble in a concentrated aqueous solution of salts. Production waste from the textile manufacturing process as described above can thus be recycled without it being necessary to burn the binder or melt the fibers.

[0100] In some embodiments, the text according to the invention is in the form of a laminate comprising at least two layers, where:

[0101] - each layer (identical or different from each other) comprises textile fibers and a polymer binder. - said at least two layers are connected to each other by a polymer binder, and

[0102] - the polymer binder of at least one of said layers or which binds the layers together is a binder based on a polyelectrolyte complex as defined in the present application.

[0103] The present application therefore also relates to a recycling process comprising

[0104] - immersing a textile according to the invention in an aqueous solution of a salt chosen from the group consisting of alkali or alkaline-earth metal halides, preferably alkali metal halides, the salt concentration of the aqueous solution being at least equal to 2.0 mol / L, so as to obtain the dissolution of the cationic and anionic polyelectrolytes in the aqueous salt solution,

[0105] - separation of textile fibers from the aqueous salt solution containing cationic and anionic polyelectrolytes, and

[0106] - the reuse of recovered textile fibers, preferably for the manufacture of a textile (for example, a non-woven mat).

[0107] The immersion step can be implemented by introducing the textiles to be recycled into a volume of saline solution maintained under continuous stirring. The contact of the polyelectrolyte complex binder with the saline solution reconverts the solid binder into a viscous coacervate and thus allows the separation of the textile fibers from the coacervate, for example by filtration or sedimentation.

[0108] The recovered textile fibers can then be reused. In the case of long fibers, they can be cut before being recycled to make new non-woven textile fiber mats. The same applies to the recovered coacervate, which can then be used as a binder to impregnate a layer of textile fibers.

[0109] The contact time required for the fluidification of the solid binder (polyelectrolyte complex) depends on the salt concentration of the aqueous recycling solution. The higher the concentration, the faster the fluidification of the solid binder.

[0110] The salt concentration of the aqueous solution is preferably between 2.2 and 4.0 mol / L, in particular between 2.5 and 3.0 mol / L. Within this salt concentration range, the contact time required for fluidification is generally between 1 minute and 10 minutes.

[0111] Example

[0112] Preparation of the polycation saline solution:

[0113] A concentrated aqueous solution of tannic acid with a concentration of 0.14 g / mL is prepared. 45 μL of the concentrated tannic acid solution is added to 15.9 mL of water using a micropipette, acidified by adding HCl (1 M) to pH = 1, and then 5.45 g of KBr is added. 3.0 g of EVA 462 (polydiallyldimethylammonium chloride, PDADMAC) is then added to the resulting aqueous composition and the mixture is stirred until the polyelectrolyte is completely dissolved. After the polycation has dissolved, 0.001 g of FeCl3 is added with stirring.

[0114] Preparation of the polyanion saline solution:

[0115] 5.45 g of KBr are added to 16.4 ml of water previously acidified to pH 1 with HCl. 2.65 g of Versai TL 130, having a polystyrene sulfonate (PSS) content of approximately 30% (Nouryon) are added to the resulting saline acid solution.

[0116] Preparation of the coacervate:

[0117] After complete dissolution of the polyelectrolytes, the polyanion solution (polystyrene sulfonate, PSS) is poured into the polycation solution (polydiallyldimethylammonium chloride, PDADMAC) with vigorous stirring. The mixture is left to stand for a few minutes until phase separation occurs. The upper phase (supernatant) is discarded. The lower phase (coacervate) is green in color and changes color (red) when neutralized by adding 0.3 mL of AMP 95 (ANGUS Chemical Company) to pH > 5.

[0118] Preparation of a non-woven fabric (laboratory scale)

[0119] 4 g of short glass fibers are dispersed in 2 liters of water for 10 minutes with vigorous stirring. The glass fiber dispersion is introduced into a semi-automatic sheet-making machine containing, at the bottom, a non-woven mat of polyethylene fibers. The machine is programmed to operate in cycles (40 seconds of stirring, 10 seconds of sedimentation, and removal of process water).

[0120] After removing the process water, a second non-woven polyethylene fiber mat is placed on the glass fiber layer. The sandwich assembly (polyethylene mat-glass fiber-polyethylene mat) is transferred to a suction table where the excess process water is sucked off.

[0121] The sandwich assembly is then immersed in the coacervate of PSS and PDADMAC reinforced with tannic acid and FeCI3, the excess liquid is sucked off by passing over a vacuum table, then the assembly is again immersed in the coacervate and passed over the vacuum table again.

[0122] The upper nonwoven polyethylene fiber mat is removed and the glass fiber layer, impregnated with the coacervate and supported by the polyethylene fiber nonwoven mat, is placed on the rack of an oven where the second nonwoven polyethylene fiber mat is carefully removed. The glass fiber layer impregnated with the coacervate is dried for 3 minutes at 150 °C. After this drying step, the glass fiber mat is immersed in water for 15 minutes to remove the salt (KBr), and then dried again for 3 minutes at 150 °C. The resulting glass veil has a surface density of 52.4 g / m2 and a loss on ignition (LOI) of approximately 28%.

[0123] The mechanical performance of the veil is comparable to a non-woven mat prepared with a conventional thermoset binder based on urea-formaldehyde resins.

[0124] Recycling

[0125] A sample of non-woven glass fibre mat prepared as described above is introduced into an aqueous solution of KBr (2.5 mol / L) and stirred at moderate speed (maximum 600 rpm). After only 5 minutes of stirring, the dissolution of the binder from the non-woven mat and the separation of the fibres, which can be recovered by simple filtration, are observed.

[0126] The filtrate recovered from the filtration step contains water, salt (KBr), polyanion, polycation and can be recycled to the coacervate composition preparation step.

Claims

CLAIMS 1. Textile comprising textile fibers and a non-crosslinked, water-insoluble polymer binder, said polymer binder comprising a solid polyelectrolyte complex formed of an anionic polyelectrolyte and a cationic polyelectrolyte.

2. Textile according to claim 1, characterized in that the cationic polyelectrolyte and the anionic polyelectrolyte are present in respective quantities such that the ratio of the number of positive charges present on the cationic polyelectrolyte to the number of negative charges on the anionic polyelectrolyte is between 0.5 and 2, preferably between 0.6 and 1.8, in particular between 0.7 and 1.6, more preferably between 0.8 and 1.4, and ideally between 0.9 and 1.

2.

3. Textile according to claim 1 or 2, characterized in that the anionic polyelectrolyte and the cationic polyelectrolyte together represent from 50% to 100% by weight, preferably from 70% to 98% by weight, in particular from 80% to 95% by weight of the polymer binder.

4. Textile according to any one of the preceding claims, characterized in that the anionic polyelectrolyte and / or the cationic polyelectrolyte are linear polymers, free of branches.

5. Textile according to any one of the preceding claims, characterized in that the anionic and cationic polyelectrolytes each have a weight-average mass of between 1,000 and 2,000,000, preferably between 50,000 and 700,000 Da, in particular between 100,000 and 400,000 Da.

6. Textile according to any one of the preceding claims, characterized in that the ratio of the weight average mass of the anionic polyelectrolyte to the weight average mass of the cationic polyelectrolyte is between 0.4 and 1.6, preferably between 0.7 and 1.3, in particular between 0.8 and 1.

2.

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

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

9. Textile according to any one of the preceding claims, characterized in that the textile fibers comprise mineral fibers, preferably glass fibers, and optionally organic fibers such as polyester fibers, cellulose fibers or polyamide fibers.

10. Textile according to any one of the preceding claims, characterized in that the textile fibers are glass fibers, synthetic polymer fibers, natural fibers or a mixture of such textile fibers of different nature.

11. Textile according to any one of the preceding claims, characterized in that the solid polyelectrolyte complex further contains a water-soluble polyphenol comprising at least one polyhydroxylated aromatic cycle.

12. Textile according to any one of the preceding claims, characterized in that the solid polyelectrolyte complex further contains at least one water-soluble salt of a transition metal, preferably a salt of iron, zinc, cobalt, copper or vanadium.

13. Textile according to any one of the preceding claims, characterized in that at least one of said anionic polyelectrolyte and said cationic polyelectrolyte is a strong polyelectrolyte.

14. Textile according to any one of the preceding claims, characterized in that the textile is a non-woven mat.

15. A method of manufacturing a textile according to any one of the preceding claims, comprising - the production of a layer of textile fibers, - impregnating the textile fiber layer with a polyelectrolyte coacervate composition containing an anionic polyelectrolyte, a cationic polyelectrolyte and a salt selected from the group consisting of alkali or alkaline earth metal halides, preferably alkali metal halides, - if necessary, removal of excess polyelectrolyte coacervate composition, - possibly partial or complete drying of the layer of textile fibers, impregnated with the polyelectrolyte coacervate composition, - bringing the layer of textile fibers, impregnated with the polyelectrolyte coacervate composition, into contact with water so as to extract the salt from the polyelectrolyte coacervate composition and to convert the polyelectrolyte coacervate composition into a solid polyelectrolyte complex.

16. Method of manufacturing a textile according to claim 15, characterized in that the salt concentration of the polyelectrolyte coacervate composition is between 10% and 50% by weight, preferably between 15% and 45% by weight.

17. A method of manufacturing a textile according to claim 15 or 16, characterized in that the polyelectrolyte content of the polyelectrolyte coacervate composition is between 1% and 30% by weight, preferably between 3% and 20% by weight, in particular between 4% and 15% by weight.

18. Recycling process comprising - immersing a textile according to any one of claims 1 to 14 in an aqueous solution of a salt chosen from the group consisting of alkali or alkaline earth metal halides, preferably alkali metal halides, the salt concentration being at least 2.0 mol / L, preferably between 2.2 and 4.0 mol / L, in particular between 2.5 and 3.0 mol / L, so as to obtain the dissolution of the cationic and anionic polyelectrolytes in the aqueous salt solution, - separation of the fibers from the aqueous salt solution containing the cationic and anionic polyelectrolytes, and - the reuse of recovered fibers, preferably for the manufacture of a textile.