WO2024235940A1 - Method for recycling webs of mineral fibres - Google Patents

Abstract

The present invention relates to a method for recycling a non-woven web containing mineral fibres and a binder comprising at least one thermoset resin that is not a phenolic resin, the method comprising a step of bringing the non-woven web into contact with at least one amine in liquid or gaseous form, for a sufficient period of time to decompose the binder. The invention further relates to the use of an amine to decompose the binder contained in a non-woven web containing mineral fibres and a binder comprising at least one thermoset resin that is not a phenolic resin.

Description

Description

Title: Process for recycling mineral fiber sails

TECHNICAL AREA

The present invention relates to the field of non-woven fabrics based on mineral fibers, which are intended in particular for application in the field of construction.

The invention relates more particularly to a method for recycling a non-woven web containing mineral fibers and a binder comprising at least one thermoset resin other than a phenolic resin, said method comprising a step consisting of placing said web in contact with at least one amine in liquid or gaseous form, for a time sufficient to decompose said binder.

BACKGROUND OF THE INVENTION

Mineral fibre veils (also called “non-woven”, “non-woven” or “mats”) can be manufactured using known processes operating by dry or wet method.

In the dry process, molten material from a furnace is fed to a set of spinnerets from which filaments flow by gravity and are drawn by a gas flow. The filaments are collected on a conveyor where they intertwine.

On the upper face of the material thus formed, a sizing composition containing at least one thermosetting resin is applied using a suitable device, most often operating by curtain deposition, and the excess sizing composition is removed by suction at the opposite face. The material then enters a hot air oven whose temperature is adapted to remove the water and crosslink the resin in a fairly short time, then the veil of mineral fibers formed is collected and rolled up.

In the wet process, the veil is obtained from an aqueous dispersion of chopped mineral fibres which is deposited by means of a forming head on a conveyor provided with perforations and the water is extracted through the conveyor by means of a suction box. The chopped fibres remaining on the conveyor form a veil which is treated under the same conditions as those described for the dry process.

In the above-mentioned processes, the binder obtained from the sizing composition has the function of binding the fibers together and of giving the web obtained mechanical properties adapted to the desired use, in particular sufficient rigidity to be able to be handled easily without risk of it being torn. The sizing composition applied to the mineral fibers is generally in the form of an aqueous solution containing at least one thermosetting resin such as a urea-formaldehyde resin (US-6,993,876) or a resin polyester obtained from a hydrogenated sugar and a polycarboxylic acid (WO2022/106789), for example, as well as additives.

Mineral fiber veils can be used in particular as wall coverings, surfacing materials or as a support layer for acoustic or sound insulation products. Alternatively, they can be used in the manufacture of shingles or waterproofing membranes for bituminous terraces or roofs. The shingles generally consist of one or more layers of glass fiber veil impregnated with asphalt, one surface of which is provided with granules and the other surface is covered with smaller particles. Examples of shingles are described in particular in documents US-4,352,837; US-5,181,361; US-5,287,669; US-5,347,785; US-5,375,491; US-5,421,134; and US-5,426,902. Similar structures to these shingles are also sometimes applied to building facades and constitute another application of mineral fiber veils.

The sails at the end of production are generally cut, particularly on their edges, before being put into rolls. Their manufacture therefore generates unusable cutting waste. Other waste consists of the first and last sails obtained during a manufacturing cycle or during transitions when changing production parameters, which do not necessarily have the desired properties (grammage, porosity and/or binder rate). Currently, this waste is landfilled. However, given the cost of landfilling and its environmental impact, it would be desirable to be able to recycle these sails.

In this context, the inventors have developed a simple process for breaking down the binder by aminolysis at a moderate temperature, while preserving the structure of the fibers. The process according to the invention thus makes it possible to recycle nonwoven webs under economically acceptable and more environmentally favorable conditions.

It has already been suggested in application US 2019/0241713 to recycle a composite material based on a matrix formed of a phenolic resin incorporating glass fiber reinforcements. In this process, the composite material is subjected to an aminolysis step to recover, on the one hand, monomers or oligomers capable of reforming a resin and, on the other hand, mineral fibers. However, it is not suggested that this process could be applied to products other than these composites, which are essentially intended for the manufacture of aeronautical or automobile parts, and in particular that this process could be used in the recycling of materials containing predominantly mineral fibres. Furthermore, the inventors have discovered that this aminolysis process has a universal character, in the sense that it can be applied to non-woven webs containing all types of binders, which was not foreseeable in view of document US2019/0241713 which suggests that the described process is not even effective on all types of phenolic resin.

SUMMARY OF THE INVENTION

The present invention thus relates to a method for recycling a non-woven web containing mineral fibers and a binder comprising at least one thermoset resin other than a phenolic resin, said method comprising a step consisting of placing said non-woven web in contact with at least one amine in liquid or gaseous form, for a time sufficient to decompose said binder.

It also relates to the use of an amine to decompose the binder contained in a non-woven web containing mineral fibers and a binder comprising at least one thermoset resin other than a phenolic resin.

DETAILED DESCRIPTION

In the remainder of this description, the expression "between" must be understood as including the limits cited.

The present invention relates to a method for recycling a nonwoven web, for example from the collection of nonwoven web production waste. By "nonwoven web" is meant a material whose thickness is generally less than 2 mm, preferably less than 1 mm and generally between 250 and 500 pm or between 700 and 1000 pm. Its surface mass is generally between 20 and 500 g/m ² , preferably between 30 and 250 g/m ² , for example between 35 and 110 g/m ² or between 150 and 250 g/m ² .

This non-woven veil contains as its first constituent mineral fibres, which are preferably glass fibres or alternatively rock fibres. It is also possible to combine the two types of fibres.

Mineral fibers can be filaments or threads composed of a multitude of filaments and assemblies of such threads. Thus, according to a first embodiment, the mineral fiber veil is composed of discontinuous mineral filaments of a length of up to 150 mm, preferably between 1 and 100 mm and advantageously between 2 and 50 mm, and having a diameter which can vary to a large extent, for example from 5 to 30 μm.

According to a second embodiment, the mineral fiber veil is composed of mineral threads. The mineral threads can be threads composed of a multitude of mineral filaments (or base threads) or assemblies of these base threads in rovings.

The aforementioned yarns may be untwisted yarns or twisted yarns (or textile yarns), preferably untwisted.

Mineral wires, especially glass wires, are generally cut to a length of up to 100 mm, preferably between 6 and 40 mm, in particular between 10 and 35 mm.

The diameter of the glass filaments constituting the yarns can vary to a large extent, for example from 5 to 30 pm. Similarly, wide variations can occur in the linear mass of the yarn which can range from 34 to 1500 tex.

The glass constituting the filaments can be of any type, for example C, E, R, ECR or AR (alkali resistant). C and E glass are preferred.

In one embodiment, the nonwoven web may further be reinforced by a network of mineral threads, in particular glass threads with or without twist, preferably arranged parallel to each other. Each thread is composed of a multitude of very fine filaments. These mineral threads are generally deposited on the web conveyor device in the direction of advancement of the web and distributed over all or part of the width of the mat. They are preferably deposited between two layers of mineral fibers.

In one embodiment, the nonwoven web therefore comprises mineral threads, in particular glass threads, arranged parallel to each other, and preferably in the machine direction, between two layers of mineral fibers arranged randomly.

Apart from the mineral fibres and any mineral threads, the nonwoven web used according to the invention contains at least one binder. In the remainder of this description, the term "binder" means a product comprising a crosslinked, insoluble and infusible polymer system. It can be obtained by hardening a sizing composition, which consists of an aqueous solution or dispersion suitable for being deposited by curtain on the mineral fibres and containing a mixture of organic and optionally inorganic compounds (sometimes referred to as "resin") capable of reacting with each other at high temperature. According to the invention, the binder comprises a thermoset resin other than a phenolic resin. More generally, it is preferred that the nonwoven web does not contain phenolic resin.

In one embodiment of the invention, the binder comprises a urea-formaldehyde resin or a melamine-formaldehyde resin.

In another embodiment of the invention, the binder comprises the product of the reaction between compounds one of which comprises:

- at least one saccharide chosen from monosaccharides, disaccharides, oligosaccharides, polysaccharides and their mixtures, hereinafter referred to as "the saccharide", and/or

- at least one polycarboxylic acid chosen from monomeric and polymeric carboxylic acids, their anhydrides, their copolymers and their mixtures, hereinafter referred to as "polycarboxylic acid".

Thus, in a first embodiment, the binder may comprise the product of the reaction of the polycarboxylic acid with a co-reactant chosen from: at least one saccharide chosen from monosaccharides, disaccharides, oligosaccharides, polysaccharides and mixtures thereof; at least one alkanolamine; at least one polyol other than a saccharide; at least one polyamine; and mixtures thereof.

The polycarboxylic acids used in this embodiment are preferably polymeric polycarboxylic acids, generally having a molar mass greater than 1000, obtained from monomers chosen from: acrylic, methacrylic, crotonic, isocrotonic, maleic, cinnamic, itaconic, 2-methylmaleic or 2-methylitaconic acid; succinic, glutaric, trimellitic, maleic, itaconic, phthalic, tetrahydrophthalic, acrylic and methacrylic anhydrides; and mixtures of these acids and anhydrides with each other and/or with a vinyl comonomer.

In this embodiment, it is preferred that the co-reactant be selected from alkanolamines and polyols other than saccharides (the term "saccharides" including hydrogenated sugars).

Examples of polyols used as co-reactants are alkylene glycols, in particular ethylene glycol, glycerol, pentaerythritol, trimethylolpropane, resorcinol, catechol, pyrogallol, 1,4-cyclohexanediol, and addition polymers comprising at least two hydroxyl groups, such as poly(vinyl alcohol). As binders based on carboxylic polymers and polyols, mention may be made of those described in application US2004/002567.

Instead of or in addition to a saccharide, at least one alkanolamine may be used as a co-reactant with the polycarboxylic acids or their anhydrides, such as the addition/elimination products of the anhydrides of aliphatic and/or aromatic polycarboxylic acids with alkanolamines such as diethanolamine, triethanolamine, diisopropanolamine, triisopropanolamine, methyldiethanolamine, ethyldiethanolamine, n-butyldiethanolamine, methyldiisopropanolamine, ethylisopropanolamine, ethyldiisopropanolamine, 3-amino-1,2-propanediol, 2-amino-1,3-propanediol and tris(hydroxymethyl)aminomethane, preferably diethanolamine. Binders of this type are described in particular in applications W02004/007615 and W02006/0061249.

Alternatively, the polycarboxylic acids used in this embodiment of the present invention may be monomeric polycarboxylic acids, generally having a molar mass of less than or equal to 1000. In other words, this term does not encompass polymers obtained by polymerization of monomeric carboxylic acids.

Polycarboxylic acids chosen from the group consisting of dicarboxylic acids, tricarboxylic acids and tetracarboxylic acids will preferably be used.

The dicarboxylic acids are for example selected from the group consisting of oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, malic acid, tartaric acid, tartronic acid, aspartic acid, glutamic acid, fumaric acid, itaconic acid, maleic acid, traumatic acid, camphoric acid, phthalic acid, tetrahydrophthalic acid, chlorendic acid, isophthalic acid, terephthalic acid, mesaconic acid and citraconic acid. Tricarboxylic acids are for example selected from the group consisting of citric acid, tricarballylic acid, 1,2,4-butanetricarboxylic acid, aconitic acid, hemimellitic acid, trimellitic acid and trimesic acid. Tetracarboxylic acids are for example 1,2,3,4-butanetetracarboxylic acid and pyromellitic acid.

The particularly preferred polycarboxylic acid is citric acid. In this case, the co-reactant is preferably a saccharide selected from monosaccharides, disaccharides, oligosaccharides, polysaccharides and mixtures thereof.

The monosaccharide may be selected from monosaccharides containing 3 to 8 carbon atoms, preferably 5 to 7 carbon atoms. Preferred monosaccharides are hexoses such as glucose, mannose, galactose, psicose and fructose, as well as pentoses such as xylose, arabinose, ribose, ribulose, lyxose and xylulose.

The disaccharides may be chosen from sucrose, lactose and maltose, preferably sucrose.

For the purposes of this description, the term "oligosaccharides" means compounds containing from 3 to 8 monosaccharide units in the form of aldoses and/or ketoses, such as raffinose, manninotriose, stachyose and verbascose.

Examples of polysaccharides are arabinan, galactan, glucan, manan, and xylan.

The oligo- and polysaccharides (optionally mixed with mono- and/or disaccharides) may alternatively be extracted from plants. In particular, starch hydrolysates (including dextrins and glucose syrups) and cellulose and/or hemicellulose hydrolysates may be mentioned, in particular hydrolysates of bagasse or sugar cane molasses or beet molasses. The starch itself may be extracted from plants selected from vegetables, legumes, fruits and seeds, in particular rice, peas, potatoes, cassava, sweet potatoes, wheat, corn, rye, rice, barley, millet, oats, sorghum, chestnuts or hazelnuts.

The saccharides used in the manufacture of the binder can be chosen from reducing sugars, non-reducing sugars and hydrogenated sugars.

The term "hydrogenated sugar" means all the products resulting from the reduction of a saccharide selected from monosaccharides, disaccharides, oligosaccharides and polysaccharides and mixtures of these products. Hydrogenated sugars are also called sugar alcohols, alditols or polyols. They can be obtained by catalytic hydrogenation of saccharides. The hydrogenation can be carried out by known methods operating under conditions of high hydrogen pressure and temperature, in the presence of a catalyst selected from the elements of groups IB, MB, IVB, VI, VII and VIII of the periodic table of elements, preferably from the group comprising nickel, platinum, palladium, cobalt, molybdenum and mixtures thereof. The preferred catalyst is Raney nickel. The hydrogenated sugar(s) are advantageously chosen from the group consisting of erythritol, arabitol, xylitol, sorbitol, mannitol, iditol, maltitol, isomaltitol, lactitol, cellobitol, palatinitol, maltotritol, and the hydrogenation products of starch hydrolysates or hydrolysates of lignocellulosic materials, in particular hemicellulose, in particular xylans and xyloglucans.

Particular preference will be given to using a hydrogenated sugar chosen from the group formed by maltitol, xylitol, sorbitol and the hydrogenation products of starch hydrolysates or lignocellulosic materials.

The reducing sugars are preferably selected from monosaccharides such as glucose, galactose, mannose and fructose, disaccharides such as lactose, maltose, isomaltose, cellobiose and mixtures thereof, as well as the starch or lignocellulosic material hydrolysates described above. Glucose, xylose and mixtures thereof, in particular glucose, will preferably be used.

The non-reducing sugars are preferably diholosides such as trehalose, isotrehaloses, sucrose, isosucroses and mixtures thereof. Sucrose is particularly preferred.

Thermosetting resin systems for mineral wool based on saccharides and polycarboxylic acids are described in detail in international applications WO2009/080938, WO2010/029266, WO2013/014399, WO2013/021112 and WO2015/132518. It is preferred to use bio-based reagents comprising at least 70% by weight, preferably at least 80%, and most preferably at least 90% by weight of hydrogenated sugars and citric acid.

Other co-reactants include polyamines such as diethylenetriamine, triethylenetetramine or tetraethylenepentamine. Binders based on polycarboxylic acids and polyamines are described in particular in application US 2007/0173588.

In another embodiment of the invention, the binder comprises the product of the reaction of at least one saccharide as described above with a co-reactant other than a polycarboxylic acid or in addition to said polycarboxylic acid.

In the particular case where the saccharide comprises a reducing sugar, for example glucose or xylose, preferably glucose, at least one chosen co-reactant is preferably used among nitrogenous or amino compounds, in particular ammonia; a primary or secondary amine, linear, branched or cyclic (optionally heterocyclic); a protein, a peptide or an amino acid; an amino-amide; or an ammonium salt of a monomeric or polymeric carboxylic acid, such as citric acid, of a mineral acid, such as sulfuric or phosphoric acid, or of an organophosphonic or organosulfonic acid; and mixtures thereof. Such binders based on Maillard reagents are known for example from applications WO2007/014236, WO2009/019232 and WO2012/037451.

The binder of the nonwoven web of mineral fibers comprises from 15% to 100% by weight, preferably from 50 to 95% by weight, and more preferably from 75 to 90% by weight, of thermoset polymer obtained by crosslinking a resin.

The other constituents of the binder may be derived from the sizing composition or from the reaction between components of the sizing composition and at least one of the constituents of the resin described above and/or produced by heating components of the sizing composition. The sizing composition may thus comprise at least one component chosen from: a catalyst, which may in particular be chosen from Lewis bases and acids, such as clays, colloidal or non-colloidal silica, amines, quaternary amines, metal oxides (including ZnO and CaO), metal sulfates, metal chlorides, urea sulfates, urea chlorides and silicate-based catalysts, or a compound containing phosphorus, for example an alkali metal hypophosphite salt, an alkali metal phosphite, an alkali metal polyphosphate, an alkali metal hydrogen phosphate, a phosphoric acid or an alkylphosphonic acid, the alkali metal advantageously being sodium or potassium, or a compound containing fluorine and boron, for example tetrafluoroboric acid or a salt of this acid, in particular an alkali metal tetrafluoroborate such as sodium or potassium, an alkaline earth metal tetrafluoroborate such as calcium or magnesium, a zinc tetrafluoroborate and an ammonium tetrafluoroborate, preferably sodium hypophosphite, sodium phosphite and mixtures of these compounds; a silane, in particular an aminosilane; an oil; urea; glycerol; a silicone; an “extender” chosen for example from lignin derivatives such as ammonium lignosulfonate (LSA) or sodium lignosulfonate and animal or vegetable proteins; a pH adjuster; a flame retardant; a surfactant; a rheology modifier; an antifoaming agent; and mixtures thereof. The sizing composition further contains water. Furthermore, the sizing composition used for the manufacture of the binder may contain at least one polysaccharide, as described in application WO2016/00106, such as an optionally modified starch or a dextrin (WO2022/106789) or one or more ethylene-vinyl acetate copolymers, as described in application WO2018/138429, or even one or more latexes.

The web advantageously contains from 60 to 95% by weight of mineral fibers and preferably from 65 to 90% by weight of mineral fibers, for example from 75 to 85% by weight of mineral fibers, relative to the dry weight of the web. It advantageously contains from 5 to 40% by weight of binder, preferably from 10 to 35% by weight of binder, for example from 15 to 25% by weight of binder, relative to the dry weight of the web. In one embodiment of the invention, the weight ratio of fibers to binder is between 3:1 and 5:1.

When the binder consists solely of combustible organic components, this binder content is identical to what is usually called in the technical field of glass textiles the loss on ignition (LOI). The binder may, however, contain a certain fraction of mineral components, for example mineral particulate fillers. This fraction generally does not exceed 20% by weight of the binder. When the binder contains such a mineral filler, its loss on ignition (LOI) will therefore be lower than the binder content of the nonwoven web of mineral fibres.

In the method according to the present invention, the nonwoven web comprising a binder as described above is reacted with at least one amine.

The amine that can be used in the process according to the invention can be in liquid or gaseous form. It comprises at least one compound chosen from: ammonia; hydrazine; a primary or secondary hydrocarbon mono- or diamine, saturated or unsaturated, linear, branched or cyclic, optionally aromatic, the hydrocarbon chain of which contains from 1 to 20 carbon atoms and can optionally be substituted by at least one hydroxyl group and/or interrupted by at least one oxygen atom; and mixtures thereof.

Examples of monoamines are: ethylamine, propylamine, n-butylamine, sec-butylamine, /so-butylamine, tert-butylamine, pentylamine, hexylamine, tert- octylamine, cyclohexylamine, isophorylamine, benzylamine (aniline), xylylamine, tolylamine, aminoethanol, aminopropanol, and mixtures thereof.

As monoamine, it is preferred in this invention to use aminopropanol.

As diamines, the following can be used: l-amino-3-aminomethyl-3,5,5-trimethylcyclohexane (IPDA), bis-(4-aminocyclohexyl)-methane, bis-(4-amino-3-methylcyclohexyl)methane, 1,6-diamino hexane, 2-methyl pentamethylenediamine, ethylenediamine, 1,2- and 1,3-propanediamines, 2-methyl-l,2-propanediamine, 2,2-dimethyl-l,3-propanediamine, 1,3- and 1,4-butanediamines, 1,3- and 1,5-pentanediamines, 2-methyl-l,5-pentanediamine, 1,6-hexanediamine, 2,5-dimethyl-2,5-hexanediamine, 2,2,4- or 2,4,4-trimethyl-1,6-hexanediamine, 1,7-heptanediamine, 1,8-octanediamine, 1,9-nonanediamine, 1,10-decanediamine, 1,11-undecanediamine, 1,12-dodecanediamine, 2,4- and 2,6-hexahydrotoluylenediamines, 2,4'- and 4,4'-diamino-dicyclohexylmethanes, 1,3- and 1,4-cyclohexanediamines, 1,3- or 1,4-bis(methylamino)-cyclohexane, 1,8-p-menthanediamine, phenylenediamine, 2,4- and 2,6-toluylenediamines, 2,3- and 3,4-toluylenediamines, o-, m- or p-xylylenediamines, 2,4'- and 4,4'-diaminodiphenyl methanes, guanidine, /V-(2-aminoethyl)-1,3-propanediamine, benzidine, /V,/V'-di-(2-aminoethyl)piperazine and mixtures thereof.

The diamine may also be a polyetheramine. A polyetheramine is a polyamine comprising ether linkages (-O-), more particularly ethylene oxide (-O-CH2- CH2) and/or propylene oxide (-O-CH2-CHCH3-) units.

Examples of polyetheramines are compounds marketed by Hunstmann under the Jeffamine® brand name, including the Jeffamine® D, ED and EDR series. These series include, but are not limited to, the following references: Jeffamine®D-230, Jeffamine® D-400, Jeffamine® D-2000, Jeffamine® D-4000, Jeffamine® ED-600, Jeffamine® ED-900, Jeffamine® ED-2003, Jeffamine® EDR-148, Jeffamine® EDR-176.

A preferred diamine according to this invention is ethylene diamine.

In this description, the term "amine" refers to both a single amine and a mixture of amines.

The nonwoven web may be brought into contact with the amine by any means enabling the entire material to be treated to be brought into contact with the amine and in particular, in the case where the amine is in the gas phase, by passing the amine into a container containing the web. nonwoven and, in the case where the amine is in the liquid phase, by dipping, spraying or coating, preferably by immersing the nonwoven web in a solution containing, or consisting of, the amine. When the amine is in the liquid phase, it may optionally be mixed with an organic solvent and/or water, although it is preferred not to use organic solvents. The contacting of the nonwoven web with the amine may be carried out at a temperature of -20 to 250°C and is preferably carried out at the boiling point of the amine, for a period ranging for example from one minute to 48 hours, preferably from 2 hours to 30 hours.

The method according to the invention may further comprise steps of recovering the nonwoven web treated with the amine, washing, preferably with water or with an aqueous solution, and drying, in order to obtain mineral fibers, which can then be reused in the manufacture of a nonwoven web.

EXAMPLES

The following examples illustrate the invention without, however, limiting it.

General protocol

The glass veil is cut into pieces of approximately 2x2 cm. The pieces are then placed in contact with the solvent (amine) in a flask, in a proportion of between 2 and 5% m/v of veil in the solvent. The mixture is heated in an oil bath at 100-180 °C for 1-8 h. The fibres are recovered by filtration and then rinsed with water. If they are to be reused, the fibres are generally not dried. Alternatively, the fibres can be dried by rinsing with acetone and then drying at room temperature.

Measurement of the quantity of binder by “loss on ignition”

Recycled fibres (0.5 to 1.0 g) are subjected to pyrolysis at 550 °C for 1 h in air. The quantity of residual binder after solvolysis is assimilated to the mass lost by pyrolysis. It is calculated as follows:

[Chem 1]

Final LAW (100

The initial LOI of the veil is determined in the same way.

EXAMPLE 1: Decomposition of a urea-formaldehyde resin binder Tests were carried out on a sample of a nonwoven web having a thickness of 330 pm and a surface mass of 35 g/m ² , comprising glass fibres and a binder based on urea-formaldehyde resin.

The results of these tests are presented in the Table below:

[Table 1]

These tests show that amines allow effective solvolysis of urea-formaldehyde type binders.

In addition, the general appearance of the fibers was assessed before and after treatment and their average diameter was measured: no changes were observed, as shown in the Table below:

[Table 2]

EXAMPLE 2: Decomposition of an acrylic resin binder

Tests were carried out on samples of nonwoven fabric with a thickness of 350 pm and a surface mass of 35 g/ ^m2 , comprising glass fibres and an acrylic resin binder.

The results of these tests are presented in the Table below:

[Table 3]

These tests show that amines allow effective solvolysis of acrylic resin binders.

The general appearance of the fibers was evaluated before and after treatment: no modification was observed.

Claims

Claims 1. A method of recycling a nonwoven web containing mineral fibers and a binder comprising at least one thermoset resin other than a phenolic resin, said method comprising a step of placing said nonwoven web in contact with at least one amine in liquid or gaseous form, for a time sufficient to decompose said binder. 2. Method according to claim 1, characterized in that the binder comprises a urea-formaldehyde resin or a melamine-formaldehyde resin. 3. Method according to claim 1, characterized in that the binder comprises the product of the reaction between compounds, one of which comprises: - at least one saccharide chosen from monosaccharides, disaccharides, oligosaccharides, polysaccharides and their mixtures, and/or - at least one polycarboxylic acid chosen from monomeric and polymeric carboxylic acids, their anhydrides, their copolymers and their mixtures. 4. Method according to claim 3, characterized in that the binder comprises the product of the reaction between a polycarboxylic acid chosen from polymeric carboxylic acids, their anhydrides and their mixtures and a co-reactant chosen from alkanolamines and polyols other than saccharides. 5. Process according to claim 4, characterized in that the polycarboxylic acid is obtained from monomers chosen from: acrylic, methacrylic, crotonic, isocrotonic, maleic, cinnamic, itaconic, 2-methylmaleic or 2-methylitaconic acid; succinic, glutaric, trimellitic, maleic, itaconic, phthalic, tetrahydrophthalic, acrylic and methacrylic anhydrides; and mixtures of these acids and anhydrides with each other and/or with a vinyl comonomer. 6. Process according to any one of claims 1 to 5, characterized in that the amine in liquid or gaseous form is chosen from: ammonia; hydrazine; a primary or secondary hydrocarbon mono- or diamine, saturated or unsaturated, linear, branched or cyclic, optionally aromatic, the hydrocarbon chain of which contains from 1 to 20 atoms of carbon and may optionally be substituted by at least one hydroxyl group and/or interrupted by at least one oxygen atom; and mixtures thereof. 7. Method according to any one of claims 1 to 6, characterized in that the contacting of the non-woven web and the amine is carried out by immersion of the non-woven web in a solution containing, or consisting of, the amine, preferably at the boiling temperature of the amine. 8. Method according to any one of claims 1 to 6, characterized in that the amine is in gaseous form and the contacting of the non-woven web and the amine is preferably carried out by passing the amine into a container containing the non-woven web. 9. Method according to any one of claims 1 to 8, characterized in that it further comprises steps of recovering the non-woven web treated with the amine, washing, preferably with water or with an aqueous solution, and drying, in order to obtain mineral fibers. 10. Use of an amine as defined in claim 1 or 6 to decompose the binder contained in a non-woven web containing mineral fibers and a binder comprising at least one thermoset resin other than a phenolic resin.