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-crosslinked polymeric binder that is insoluble in water, said polymeric binder comprising a solid polyelectrolyte complex formed 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] The present invention relates to textiles comprising organic or mineral textile fibers bonded by a non-crosslinked binder that is insoluble in water and formed by a complex of oppositely charged polyelectrolytes. It also relates to a method for manufacturing such textiles and a method for recycling such textiles by solubilizing the binder in an aqueous salt solution and reusing the fibers.

[0002] The construction industry is always on the lookout for low-cost, VOC-free and recyclable materials.

[0003] In non-woven construction mats, the fibers are generally held together by a thermoset, cross-linked binder based on phenol-formaldehyde, melamine-formaldehyde or urea-formaldehyde resins, or on cross-linked organic polymers, such as acrylic polymers.

[0004] Woven or knitted textiles, especially those based on glass textile fibers, are also often coated with thermoset binders.

[0005] The production of such textiles bonded with insoluble cross-linked binders generally means that it is impossible to recycle production waste, such as offcuts cut from roll edges, rolls with manufacturing defects, or roll offcuts generated by cutting during non-wovens processing.

[0006] In the field of mineral wool-based insulation products generally containing between 5% and 10% by weight of organic binder, such production waste can be recycled by reintroducing it into the manufacturing method upstream of the melting stage.

[0007] However, such recycling by remelting 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 the present application is to propose a binder for the manufacture of textiles based on organic and / or mineral textile fibers, which allows recycling of production waste, without melting or combustion / pyrolysis, and reuse of the fibers and possibly of 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 many years in the medical and biomedical field as polyelectrolyte complexes / coacervates (PEC) (WO2011 / 149907A1, WO2011 / 106595, WO2012 / 065148, WO2016 / 011028, WO2019 / 172764), to reversibly bond textile fibers, in particular non-woven mats.

[0010] When an aqueous solution of an anionic polyelectrolyte (also referred to hereinafter as a “polyanion”) and an aqueous solution of a cationic polyelectrolyte (also referred to hereinafter as a “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 opposing polymer charges, the attraction between polyanion and polycation is reduced and solid complex formation is prevented. When the solutions are mixed, however, a phase separation is observed, with a concentrated polymer-rich phase, known as the “coacervate”, on the one hand, and a polymer-depleted supernatant on the other hand. 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 on contact with water enables 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, as solid polyelectrolyte complexes can be easily “dissolved” by simple contact with aqueous solutions of high ionic strength.

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

[0013] For this purpose, a layer of mineral or organic textile fibers is impregnated with a fluid coacervate of polyelectrolytes containing a polyanion and a polycation in solution in salt water, then this binder is solidified on contact with the fibers by bringing it into contact with water to remove the salt. The solidified binder is a polyelectrolyte complex which, although insoluble in water, is not cross-linked. The absence of cross-linking means it can be re-fluidized for fiber recycling.

[0014] In the following, the term “polyelectrolyte coacervate” will refer to a fluid or viscous aqueous composition containing, dissolved in water, a polyanion, a polycation and a water-soluble inorganic salt in a concentration sufficient to prevent the formation of a solid polyelectrolyte complex. The term “polyelectrolyte complex” refers to a solid material containing a polyanion and a polycation. The polyelectrolyte complex contains no water or water-soluble inorganic salts, except in trace amounts.

[0015] As a result, the present application relates to a textile comprising textile fibers and a non-crosslinked polymeric binder that is insoluble in water, said polymeric 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, that is, monomers carrying positive or negative charges.

[0017] The cationic polyelectrolyte (polycation) and the anionic polyelectrolyte (polyanion) are preferably present in similar quantities. Since the formation of a solid binder that gives the textile (e.g. non-woven mat) satisfactory mechanical properties relies on the electrical attraction of the opposite charges of the polyelectrolytes, the respective quantities of anionic and cationic polyelectrolytes are expressed in terms of charge quantities. Thus, the respective amounts of 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 preferentially between 0.8 and 1.4, and ideally between 0.9 and 1.2.

[0018] The term “cationic polyelectrolyte” in this application covers a single type of cationic polymer or a mixture of two or more different cationic polyelectrolytes, and the term “anionic polyelectrolyte” covers a single type of anionic polymer or a mixture of two or more anionic polyelectrolytes.

[0019] Polyelectrolytes may be either strong or weak polyelectrolytes. A strong polyelectrolyte is a polymer whose net charge, positive or negative, is substantially independent of the pH of the composition. In particular, the zeta potential of a strong cationic polyelectrolyte is positive for any pH in the range from 1 to 14, and the zeta potential of a strong anionic polyelectrolyte is negative for any pH in the range from 1 to 14. The potential can be measured using a zeta potential analyzer (e.g. “zetasizer” device) at a suitable concentration (generally greater than 0.01%, e.g. 1% by weight of polyelectrolyte relative to the volume of solution analyzed) and generally at 20° C. Examples of strong cationic polyelectrolytes are polymers comprising a plurality of quaternized amine groups. Strong anionic polyelectrolytes are, for example, polymers with a multitude of sulfonate groups (—SO3−). Poly(acrylic acid) is an example of a weak anionic polyelectrolyte, and non-quaternized polyamines are examples of weak cationic polyelectrolytes, as the net charge of these polymers depends on the pH of the solution.

[0020] Preferably, at least one of said anionic polyelectrolyte and said cationic polyelectrolyte is a strong polyelectrolyte.

[0021] In some embodiments, both the anionic polyelectrolyte and the cationic polyelectrolyte are strong polyelectrolytes.

[0022] In the present application, an anionic polyelectrolyte is a polymer with a net negative charge at pH 7, and a cationic polyelectrolyte is a polymer with a net positive charge at pH 7. 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.

[0023] As a result, the definition of anionic polyelectrolytes includes zwitterionic polyelectrolytes having an isoelectric point (pl)<7, preferably <6, and the definition of cationic polyelectrolytes includes zwitterionic polyelectrolytes having an isoelectric point>7, preferably >8. The best-known zwitterionic polyelectrolytes are proteins or polypeptides which comprise both acid (—COO−) and amino (—NH2) side groups.

[0024] In a preferred embodiment of the textile (which is for example a non-woven 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.

[0025] The cationic groups of the cationic polyelectrolyte are for example primary amine, secondary amine, tertiary amine or quaternary ammonium groups, located in the main chain or on side groups of the polymer.

[0026] The cationic polyelectrolyte is preferably selected from the group consisting of

[0027] poly(diallyldimethylammonium chloride),

[0028] poly[(2-hydroxypropyl)dimethylammonium chloride],

[0029] polyamidoamine-epichlorohydrin (PAAE),

[0030] polyethyleneimine,

[0031] poly(acrylamide-co-diallyldimethylammonium chloride),

[0032] copolymer of hydroxyethylcellulose and poly(diallyldimethylammonium chloride) (Polyquaternium-4),

[0033] copolymer of acrylamide and dimethylaminoethyl methacrylate quaternized with dimethyl sulfate (Polyquaternium-5, CAS 26006-22-4),

[0034] copolymer of dimethylaminomethyl methacrylate and alkyl methacrylate,

[0035] chitosan,

[0036] poly(quaternized N, N-(dimethylamino)ethyl methacrylate),

[0037] guar hydroxypropyltrimonium chloride,

[0038] poly(N, N-dimethyl-3,5-dimethylene piperidinium chloride),

[0039] poly(vinylbenzyltrimethylammonium chloride),

[0040] poly[3-(methacryloylamino)propyl-trimethylammonium chloride],

[0041] poly(2-(methacryloloxy)ethyl]-trimethylammonium chloride),

[0042] polyvinylamine (PVA),

[0043] poly(N, N-dimethyl-3,5-dimethylene piperidinium chloride) (PDDPC),

[0044] poly(vinylbenzyltrimethylammonium chloride) (PVBTAC),

[0045] poly(allylamine hydrochloride) (PAH), and

[0046] poly[3-(methacryloylamino)propyltrimethylammonium chloride] (PMAPTAC),

[0047] cationic dextran.

[0048] The anionic groups of the anionic polyelectrolyte are, for example, selected from the group consisting of carboxyl, sulfonate, phosphonate, boronate, sulfate, borate and phosphate residues. They can be located in the polymer's main chain or on the side groups.

[0049] In one advantageous embodiment, the anionic polyelectrolyte is selected from the group consisting of poly(acrylic acid), poly(acrylamide-co-acrylic acid), poly(sodium 4-styrenesulfonate), lignosulfonate, sodium humate, alginate, poly(sodium 2-acrylamido-2-methyl-1-propanesulfonate), hyaluronic acid, dextran sulfate and poly(vinylsulfonate sodium salt).

[0050] The anionic and cationic polyelectrolytes, as defined above, together generally represent from 50% to 100% by weight, preferably from 70% to 98% by weight, in particular from 80% to 95% by weight of the cured polymeric binder (polyelectrolyte complex), the complementary part being formed in particular by

[0051] salt residues not removed,

[0052] any functional additives or fillers, or even

[0053] polyphenols and transition metals as described in detail below, functioning as a binder reinforcement system.

[0054] In a preferred embodiment, at least one of the polyelectrolytes is a linear polymer, while the other oppositely charged polyelectrolyte may be linear or branched. In other words, the anionic polyelectrolyte and / or the cationic polyelectrolyte may be linear, unbranched polymers.

[0055] The anionic and cationic polyelectrolytes have a weight-average molecular weight (determined by light scattering) of between 1,000 and 2,000,000, preferably between 50,000 and 700,000 Da, particularly between 100,000 and 400,000 Da.

[0056] The weight-average molecular weight of the anionic polyelectrolyte is advantageously similar to that of the cationic polyelectrolyte. More specifically, the ratio of the weight-average molecular weight of the anionic polyelectrolyte to the weight-average molecular weight of the cationic polyelectrolyte is preferably between 0.4 and 1.6, more particularly between 0.7 and 1.3, and ideally between 0.8 and 1.2.

[0057] In principle, any type of textile fiber can be used, whether natural, artificial or synthetic, organic or mineral. The textile fibers of the textile of the present invention are preferably selected from glass textile fibers, synthetic polymer textile fibers, e.g. polyester or polyamide (preferably polyester), and natural textile fibers, preferably natural plant textile fibers such as flax, hemp, cotton, jute, nettle, sisal, coir, raffia, abaca, broom fibers. Of course, the textile may contain a mixture of such textile fibers of different natures.

[0058] In some embodiments, the textile fibers forming the textile comprise (preferably consist of) mineral fibers—in particular glass fibers—and optionally organic fibers such as polyester fibers, cellulose fibers or polyamide fibers.

[0059] In some embodiments, the textile fibers forming the textile comprise (preferably consist of) mineral fibers—in particular glass fibers—and optionally biodegradable organic fibers, such as polylactic acid fibers (PLA), polyglycolic acid fibers (PGA), poly(lactic-co-glycolic acid) fibers (PLGA) or cellulose fibers (e.g. Lyocell fibers).

[0060] 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.

[0061] In a preferred embodiment, the textile fibers forming the textile are glass fibers and / or polyester fibers, preferably glass fibers.

[0062] The textile can be a mat, or veil, of short fibers arranged randomly in the plane of the textile. The textile can also be a woven or knitted textile structure based on long fibers. It can also be a laid scrim made by superimposing several layers of fibers arranged parallel to one another within a single layer, the various superimposed layers being bonded together by a binder that partially or totally coats the fibers.

[0063] In a preferred embodiment, the textile of the present invention is a non-woven mat of short fibers randomly arranged 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.

[0064] The polyelectrolyte complex that binds the fibers of the textile of the present invention can be reinforced with a reinforcement system based on polyphenols and transition metals. Indeed, the mechanical performance of a textile (such as a non-woven mat) is generally improved when small quantities 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 enhanced when combined with very small quantities of a transition metal. The mechanisms involved in this reinforcement effect are probably hydrogen bonds, possibly associated with ligand-metal coordination bonds. These two types of bond 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 reversibility of binder hardening.

[0065] The solid polyelectrolyte complex binding the textile fibers of the textile, in particular of the non-woven mat of the invention, may therefore further contain at least one water-soluble polyphenol comprising at least one polyhydroxylated aromatic ring.

[0066] The amount of water-soluble polyphenol(s) generally does not exceed 1% by weight, based on the aqueous binder composition used to impregnate textile fibers. It is advantageously between 0.02% and 1.0%, preferably between 0.03% and 0.5%, more preferentially between 0.04% and 0.1% by weight of the aqueous binder composition (polyelectrolyte coacervate).

[0067] The cured 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).

[0068] The term “polyphenol” refers to an organic compound comprising at least one polyhydroxylated aromatic ring, that is, bearing at least two hydroxyl groups (—OH) on the same ring structure. A water-soluble polyphenol is one with a solubility in distilled water at 20° C. of at least 100 g / L.

[0069] In a preferred embodiment, at least some of the polyphenols used comprise at least two, preferably at least three and more preferentially at least four polyhydroxylated aromatic rings.

[0070] Polyhydroxylated aromatic rings are preferably selected from the group consisting of catechol, pyrogallol and tetrahydroxylated or pentahydroxylated aromatic rings.

[0071] 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 fairly inexpensive, bio-based ingredient with a high concentration of polyhydroxylated aromatic rings.

[0072] More recently, synthetic organic polymers made from monomers containing polyhydroxylated aromatic rings have been described (see, for example, the work of Cheng et al. in Nature Communications, 13, article no. 189 2(2022)). They could very effectively reinforce the final binder of the textile of the present invention, in particular when it is a non-woven mat.

[0073] 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.

[0074] The mechanical performance of the textile, in particular the non-woven mat, can be further enhanced by associating polyvalent transition metal ions with the polyphenol-reinforced polyelectrolyte complex. The solid polyelectrolyte complex forming the binder of the textile, in particular the non-woven 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.

[0075] 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 impregnating textile fibers.

[0076] 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.

[0077] The transition metals are preferably selected from the group consisting of iron (Fe), zinc (Zn), cobalt (Co), copper (Cu) and vanadium (V). Halides, in particular chlorides and bromides, are preferred anions of the transition metal salts used, in association with polyphenols, to reinforce polyelectrolyte complexes.

[0078] 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 may, 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 an amount of 0.01 to 1% by weight, based on the aqueous binder composition used to impregnate the textile fibers.

[0079] The invention also relates to a method for manufacturing textiles based on textile fibers bonded by a polyelectrolyte complex, as described above.

[0080] This method comprises the following steps:

[0081] manufacturing a layer of textile fibers,

[0082] impregnating 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 metal or alkaline earth metal halides, preferably alkali metal halides,

[0083] if necessary, removing the excess of polyelectrolyte coacervate composition,

[0084] if necessary, partially or completely drying the textile fiber layer impregnated with the polyelectrolyte coacervate composition,

[0085] contacting the layer of textile fibers, impregnated with the polyelectrolyte coacervate composition, with water so as to extract the salt from the polyelectrolyte coacervate composition and convert the polyelectrolyte coacervate composition into a solid polyelectrolyte complex.

[0086] In the case of a non-woven mat, the layer of textile fibers is a layer of unbonded fibers. The unbonded textile fiber layer can be produced using methods known to the textile industry, either dry or wet.

[0087] The manufacture of woven or knitted textile structures, or laid scrims formed of several superimposed layers of long fibers parallel to one another, can also be implemented using techniques and methods well known in the field of textile manufacturing.

[0088] The textile fiber layer can also be impregnated with the polyelectrolyte coacervate composition using known methods commonly used in the textile industry. Examples of such methods include dipping, spraying, rolling or curtain coating.

[0089] If necessary, excess coacervate composition is then removed by a suitable method, e.g. scraping, compression, blowing, suction, etc.

[0090] The amount of polymeric binder in the final textile is advantageously between 10 and 40% by weight, preferably between 15 and 30% by weight based on the total dry weight of the textile.

[0091] The polyelectrolyte coacervate composition can be prepared by dissolving each of the cationic and anionic polyelectrolytes separately in an aqueous solution of an inorganic salt of an alkali or alkaline earth metal, preferably an alkali or alkaline earth metal halide. 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 particularly between 0.5 and 2.0 mol / L. The higher the average molecular mass of the polyelectrolytes, the greater the ionic force of saline solution required. For weight-average masses of less than 100,000 Da, salt concentrations of between 0.2 and 1 mol / L are generally sufficient. To dissolve polyelectrolytes with weight-average masses in excess of 400,000 to form a polyelectrolyte coacervate, salinities in excess of 1.8 mol / L are required.

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

[0093] Once the anionic and cationic polyelectrolytes have dissolved completely, the two solutions are simply mixed with one another. A dense, polymer-rich lower phase, called the“coacervate”, then separates from a polymer-depleted upper phase, called the “supernatant”. The two phases can be easily separated from one another, possibly after centrifuging the mixture.

[0094] On an industrial scale, it is of course desirable 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 (alkali metal or alkaline earth metal halide) of the two solutions before mixing. It is imperative to always remove the supernatant phase, otherwise the composition will not harden after the salts have been removed.

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

[0096] The salt concentration of the polyelectrolyte coacervate composition is advantageously between 10% and 50% by weight, preferably between 15% and 45% by weight.

[0097] The polyelectrolyte content of the polyelectrolyte coacervate composition is between 1% and 30% by weight, preferably between 3% and 20% by weight and in particular between 4% and 15% by weight When polyphenols are used to reinforce the polyelectrolyte complex, they are advantageously added to the cationic polyelectrolyte solution, before or after the polyelectrolyte has been dissolved. The addition of polyphenols to the anionic polyelectrolyte solution often results in undesirable gel formation. Polyphenols can be added as they are, or dissolved in an aqueous solution of an alkali or alkaline-earth metal inorganic salt.

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

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

[0100] Various additives such as pigments, dyes, biocides, pulp-derived cellulose fibers, fillers, defoamers, flame retardants, hydrophobic agents (e.g. silicone-based agents) can be added to the coacervate in a total maximum amount equal to 30% by weight, preferably 20% by weight and ideally 10% by weight, based on the weight of the polyelectrolytes and inorganic alkali or alkaline earth metal salts.

[0101] 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, in particular between 20 and 75% by weight and ideally between 25 and 70% by weight.

[0102] After the textile fiber layer is impregnated with the coacervate composition, the mechanical strength of the impregnated textile fiber layer may be insufficient for the fiber layer to be brought into immediate contact with water to remove inorganic salts (alkali metal or alkaline earth metal halides). This is particularly the case when the textile is a non-woven mat or veil or laid scrim of several layers of superimposed fibers. In this case, it is usually useful to subject the coacervate-impregnated textile fiber layer to partial or complete drying. This drying can be achieved, 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).

[0103] Drying is generally not necessary when the textile is a woven or knitted fabric.

[0104] The impregnated textile fiber layer, which may be partially or completely dried, is then brought into contact with water. Contact can be made, for example, by spraying the impregnated textile fiber layer with water or by immersion in water. The water may be free of water-soluble salts or contain water-soluble salts in a concentration significantly lower than that of the coacervate used to impregnate the textile fiber layer.

[0105] During this step of contacting the impregnated textile fiber layer with water, the inorganic alkali or alkaline earth metal salt is removed from the coacervate, which immediately solidifies to form a polyelectrolyte complex. The result is a textile of textile fibers bonded by a solid binder based on polyelectrolytes of opposite charge.

[0106] As explained in the introduction to the present application, the main advantage of using a polyelectrolyte coacervate to bind textile fibers is the reversibility of the binder curing process. Although the polyelectrolyte complex binder is solid at room temperature and insoluble in water, it is soluble in a concentrated aqueous salt solution. Production waste from the textile manufacturing method as described above can thus be recycled without the need to burn the binder or melt the fibers.

[0107] In some embodiments, the text according to the invention is in the form of a laminate comprising at least two layers, where:

[0108] each layer (identical or different from one another) comprises textile fibers and a polymeric binder,

[0109] said at least two layers are bonded together by a polymeric binder, and

[0110] the polymeric binder of at least one of said layers or which binds the layers together is a polyelectrolyte complex binder as defined in the present application.

[0111] The present application therefore also relates to a recycling method comprising

[0112] immersing a textile according to the invention in an aqueous solution of a salt selected 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 2.0 mol / L, so that the cationic and anionic polyelectrolytes are dissolved in the aqueous salt solution,

[0113] separating the textile fibers from the aqueous salt solution containing the cationic and anionic polyelectrolytes, and

[0114] reusing recovered textile fibers, preferably for the manufacture of a textile (e.g. a non-woven mat).

[0115] The immersion step can be carried out by introducing the textiles to be recycled into a volume of saline solution maintained under continuous stirring. Contact of the polyelectrolyte complex binder with the salt solution converts the solid binder back into a viscous coacervate, enabling the textile fibers to be separated from the coacervate, for example by filtration or sedimentation.

[0116] 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 recovered coacervate, which can again be used as a binder to impregnate a layer of textile fibers.

[0117] The contact time required to fluidize the solid binder (polyelectrolyte complex) depends on the salt concentration of the aqueous recycling solution. The higher this value, the faster the solid binder fluidizes.

[0118] The salt concentration of the aqueous solution is preferably between 2.2 and 4.0 mol / L, particularly between 2.5 and 3.0 mol / L. Within this range of salt concentrations, the contact time required for fluidization is generally between 1 minute and 10 minutes.EXAMPLESPreparation of the Polycation Saline Solution

[0119] A concentrated aqueous solution of tannic acid with a concentration of 0.14 g / mL is prepared. Using a micropipette, 45 μL of the concentrated tannic acid solution is added to 15.9 mL of water, acidified with HCl (1 M) to pH=1, then 5.45 of KBr is added. Next, 3.0 g of EVA 462 (poly(diallyldimethylammonium chloride, PDADMAC) is added to the resulting aqueous composition and stirred until the polyelectrolyte is completely dissolved. After dissolving the polycation, 0.001 g FeCl3 is added with stirring.Preparation of the Polyanion Salt Solution

[0120] 5.45 g of KBr is added to 16.4 ml of water previously acidified to pH 1 with Hcl. 2.65 g of Versal TL 130, with a poly(styrene sulfonate) (PSS) content of about 30% (Nouryon), is added to the resulting acid-saline solution.Coacervate Preparation

[0121] After the polyelectrolytes are completely dissolved, the polyanion solution (poly(styrene sulfonate, PSS) is poured into the polycation solution (poly(diallyldimethylammonium chloride, PDADMAC) with vigorous stirring. The mixture is left to stand for a few minutes until phase separation appears.

[0122] The upper phase (supernatant) is removed. The lower phase (coacervate) is green and changes color (red) when neutralized by adding 0.3 mL AMP 95 (ANGUS Chemical Company) to pH>5.Non-Woven Preparation (Laboratory Scale)

[0123] 4 g of short glass fibers are dispersed in 2 liters of water for 10 minutes with vigorous stirring. The glass fiber dispersion is fed into a semi-automatic sheeting machine containing a non-woven polyethylene fiber mat at the bottom. The machine is programmed to operate in cycles (40 seconds stirring, 10 seconds sedimentation, and process water removal).

[0124] Once the process water has been removed, a second non-woven polyethylene fiber mat is placed on top of the glass fiber layer. The sandwich assembly (polyethylene mat-glass fiber-polyethylene mat) is transferred to a suction table where excess process water is drawn off.

[0125] The sandwich assembly is then immersed in the coacervate of PSS and PDADMAC reinforced with tannic acid and FeCl3, excess liquid is drawn off by passing it over a suction table, then the assembly is again immersed in the coacervate and passed over the suction table again.

[0126] The upper polyethylene fiber non-woven mat is removed and the glass fiber layer, impregnated with coacervate and supported by the polyethylene fiber non-woven mat, is placed on the grate of an oven where the second polyethylene fiber non-woven mat is carefully removed. The glass fiber mat impregnated with 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), then dried again for 3 minutes at 150° C.

[0127] The resulting glass veil has a mass per unit area of 52.4 g / m2 and a loss on ignition (LOI) of around 28%.

[0128] The veil's mechanical performance is comparable to that of a non-woven mat prepared with a conventional thermoset binder based on urea-formaldehyde resins.Recycling

[0129] A sample of glass-fiber non-woven 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 just 5 minutes'stirring, the binder dissolves from the non-woven mat and the fibers separate, allowing them to be recovered by simple filtration.

[0130] The filtrate recovered from the filtration step contains water, salt (KBr), polyanion and polycation, and can be recycled to the coacervate composition preparation step.

Claims

1. A textile comprising textile fibers and a non-crosslinked polymeric binder that is insoluble in water, said polymeric binder comprising a solid polyelectrolyte complex formed of an anionic polyelectrolyte and a cationic polyelectrolyte.

2. The textile according to claim 1, wherein the cationic polyelectrolyte and the anionic polyelectrolyte are present in respective quantities such that the ratio of a number of positive charges present on the cationic polyelectrolyte to the a number of negative charges on the anionic polyelectrolyte is between 0.5 and 2.

3. The textile according to claim 1, wherein the anionic polyelectrolyte and the cationic polyelectrolyte together represent from 50% to 100% by weight of the polymeric binder.

4. The textile according to claim 1, wherein the anionic polyelectrolyte and / or the cationic polyelectrolyte are linear, unbranched polymers.

5. The textile according to claim 1, wherein the anionic and cationic polyelectrolytes each have a weight-average mass of between 1,000 and 2,000,000.

6. The textile according to claim 1, wherein 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.

7. The textile according to claim 1, wherein the cationic polyelectrolyte is selected from the group consisting ofpoly(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,poly(quaternized 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 hydrochloride) (PAH),poly[3-(methacryloylamino)propyltrimethylammonium chloride] (PMAPTAC), andcationic dextran.

8. The textile according to claim 1, wherein the anionic polyelectrolyte is selected from the group consisting of poly(acrylic acid), poly(acrylamide-co-acrylic acid), poly(sodium 4-styrenesulfonate), lignosulfonate, sodium humate, alginate, poly(sodium 2-acrylamido-2-methyl-1-propanesulfonate), hyaluronic acid, dextran sulfate and poly(vinylsulfonate sodium salt).

9. The textile according to claim 1, wherein the textile fibers comprise mineral fibers, and optionally organic fibers.

10. The textile according to claim 1, wherein the textile fibers are glass fibers, synthetic polymer fibers, natural fibers or a mixture thereof.

11. The textile according to claim 1, wherein the solid polyelectrolyte complex further comprises a water-soluble polyphenol having at least one polyhydroxylated aromatic ring.

12. The textile according to claim 1, wherein the solid polyelectrolyte complex further comprises at least one water-soluble salt of a transition metal.

13. The textile according to claim 1, wherein at least one of said anionic polyelectrolyte and said cationic polyelectrolyte is a strong polyelectrolyte.

14. The textile according to claim 1, wherein the textile is a non-woven mat.

15. A method for the manufacture of a textile according to claim 1, comprisingmanufacturing a layer of textile fibers,impregnating a layer of textile fibers with a polyelectrolyte coacervate composition containing an anionic polyelectrolyte, a cationic polyelectrolyte and a salt selected from the group consisting of alkali metal or alkaline earth metal halides,optionally removing any excess of polyelectrolyte coacervate composition,optionally partially or completely drying the textile fiber layer impregnated with the polyelectrolyte coacervate composition,contacting the layer of textile fibers, impregnated with the polyelectrolyte coacervate composition, with water so as to extract the salt from the polyelectrolyte coacervate composition and convert the polyelectrolyte coacervate composition into a solid polyelectrolyte complex.

16. The method for manufacturing a textile according to claim 15, wherein a salt concentration of the polyelectrolyte coacervate composition is between 10% and 50% by weight.

17. The method for manufacturing a textile according to claim 15, wherein a polyelectrolyte content of the polyelectrolyte coacervate composition is between 1% and 30% by weight.

18. A recycling method comprisingimmersing a textile according to claim 1 in an aqueous solution of a salt selected from the group consisting of alkali or alkaline-earth metal halides, a salt concentration of the aqueous solution being at least 2.0 mol / L so that the cationic and anionic polyelectrolytes are dissolved in the aqueous salt solution,separating the fibers from the aqueous salt solution containing the cationic and anionic polyelectrolytes, andreusing recovered fibers, preferably for the manufacture of a textile.