WO2024235939A1 - Method for recycling mineral fibres of an insulating material - Google Patents

Abstract

The present invention relates to a method for recycling an insulating material in the form of a mat or felt of mineral wool containing mineral fibres which represent 80 to 99% of the weight of the insulating material and a binder comprising at least one thermoset resin, the method comprising a step that consists in placing the insulating material in contact with at least one amine in liquid or gaseous form, for a long enough time to decompose the binder. The invention also relates to the use of an amine to decompose the binder contained in an insulating material in the form of a mat or felt containing mineral fibres which represent 80% to 99% of the weight of the insulating material and a binder comprising at least one thermoset resin.

Description

Description

Title: Process for recycling mineral fibers from an insulating material

TECHNICAL AREA

The present invention relates to the field of thermal insulation products based on mineral wool, in particular glass or rock, and a binder comprising at least one thermoset resin.

The invention relates more particularly to a method for recycling an insulating material in the form of a mineral wool mattress or felt containing mineral fibres which represent from 80 to 99% of the weight of the insulating material and a binder comprising at least one thermoset resin, said method comprising a step consisting of placing said insulating material in contact with at least one amine in liquid or gaseous form, for a time sufficient to decompose said binder.

BACKGROUND OF THE INVENTION

The manufacture of mineral wool insulation products generally includes a step of manufacturing the wool itself, which can be implemented by different processes, for example according to the known technique of internal or external centrifugal fiberization. Centrifugation consists of introducing the molten mineral material (glass or rock) into a centrifugal device comprising a multitude of small orifices, the material being projected towards the peripheral wall of the device under the action of centrifugal force and escaping in the form of filaments. At the outlet of the centrifugal device, the filaments are stretched and driven towards a receiving member by a gas stream having a high temperature and speed, to form a sheet of fibers (or mineral wool) there.

To ensure the assembly of the fibers together and to allow the sheet to have cohesion, a sizing composition in the form of an aqueous solution containing a thermosetting resin is sprayed onto the fibers, on the path from the outlet of the centrifugal device to the receiving member. The sheet of fibers coated with the sizing is then subjected to a heat treatment, at a temperature generally higher than 100°C, in order to carry out the polycondensation of the resin and thus obtain a thermal and/or acoustic insulation product having specific properties, in particular dimensional stability, tensile strength, thickness recovery after compression and a uniform color.

The most commonly used thermosetting resins are phenolic resins belonging to the resol family. In addition to their good ability to crosslink under the conditions thermal properties, these resins are soluble in water, have a good affinity for mineral fibers, particularly glass, and are relatively inexpensive.

Other sizing compositions are based on the use of a polycarboxylic acid, monomeric or polymeric, and/or a saccharide, which may be a reducing or non-reducing sugar.

As previously indicated, after application to the mineral fibres and hardening, the sizing composition forms a binder intended to ensure the cohesion of the fibres between them and to give the insulating product thus obtained the desired mechanical properties.

The insulating materials obtained have a certain lifespan and it may be necessary to remove them from the substrate on which they are applied, particularly as part of the renovation or transformation of a building or to replace them with more efficient insulating materials. Currently, insulating materials are landfilled or incinerated, and more rarely recycled. Recycling generally involves melting the material in a furnace at very high temperatures in order to vaporize all the residues present, including the binder. The product obtained must then be subjected to a fiberizing step if the glass it contains is to be reused. This recycling process has a significant environmental impact, particularly given its energy balance.

It is also known from US application 2003/047193 A1 to recover or recycle resin coated glass fibers with a hot acid solution treatment for a time sufficient to remove resinous residues.

There is therefore a need for a more environmentally friendly process for recycling mineral wool insulation materials.

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 fibres, so that it is no longer necessary to implement the melting and fibre-drawing steps used until now. The process according to the invention thus makes it possible to recycle insulating materials under economically acceptable and more environmentally favourable conditions, since the energy balance of the process is improved compared with current recycling processes.

It has already been suggested in US application 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 apply to products other than these composites, which are in the form of laminates formed from a stack of glass fibre fabrics impregnated with phenolic resin essentially intended for the manufacture of aeronautical or automobile parts, and in particular that this process could be used in the recycling of materials mainly containing mineral fibres in the form of wool, such as insulating materials. Furthermore, the inventors have discovered that this aminolysis process has a universal character, in the sense that it can be applied to insulating materials containing all types of binders, which was not foreseeable in view of document US2019/0241713 which suggests that the process described is not even effective on all types of phenolic resin.

SUMMARY OF THE INVENTION

The present invention thus relates to a method for recycling an insulating material in the form of a mineral wool mattress or felt containing mineral fibres which represent from 80 to 99% of the weight of the insulating material and a binder comprising at least one thermoset resin, said method comprising a step consisting of placing said insulating material in contact with at least one amine in liquid or gaseous form, for a period of time sufficient to decompose said binder.

It also relates to the use of an amine to decompose the binder contained in an insulating material in the form of a mineral wool mattress or felt containing mineral fibres which represent from 80 to 99% of the weight of the insulating material and a binder comprising at least one thermoset 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 an insulating material, for example from the collection of renovation or demolition site waste or factory waste.

"Insulating material" means a material that limits the heat exchange between two surfaces that it separates and that is characterized by a thermal conductivity A of less than 0.05 W/mK and generally greater than 0.02 W/mK. It comes in the form of a mattress or felt whose thickness is generally between 10 and 400 mm, for example between 15 and 350 mm, preferably between 20 and 300 mm. Its density is preferably between 5 and 220 kg/m ³ , more preferably between 10 and 180 kg/m ³ .

The insulating material according to the present invention comprises glass wool, i.e. entangled mineral fibres, as well as a binder. More specifically, the mineral fibres represent from 80 to 99% of the weight of the insulating material. They may be glass or rock fibres or a mixture of glass and rock fibres.

Glass fibers can be of any type.

These may thus be biosoluble fibers as described in application WO2022/229571A1, having the following composition:

SiO2: between 50 and 75%, preferably between 60 and 70%

NajO: between 10 and 25%, preferably between 10 and 20%

CaO: between 5 and 15%, preferably between 5 and 10%

MgO: between 1 and 10%, preferably between 2 and 5%

CaO and MgO together preferably representing between 5 and 20%

B2O3: between 0 and 10%, preferably between 2 and 8%

AI2O3: between 0 and 8%, preferably between 1 and 6%

K2O: between 0 and 5%, preferably between 0.5 and 2%

Na2O and K2O together preferably representing between 12 and 20%

Iron oxide: between 0 and 3%, preferably less than 2%, more preferably less than 1%, other oxide(s): between 0 and 5% by weight in cumulative, preferably less than 3% in cumulative, the remainder being made up of unavoidable impurities.

Alternatively, the glass fibers may be high alumina fibers, typically having the following composition:

SiO2: between 30 and 50%, preferably between 35 and 45%,

Na2O: between 0 and 20%, preferably between 0.4 and 7%,

CaO: between 6 and 35%, preferably between 12 and 25%,

MgO: between 1 and 15%, preferably between 5 and 13%,

CaO+MgO: between 11 and 40% cumulative,

AI2O3: between 10 and 27%,

K2O: between 0 and 15%, preferably between 0 and 1%, Iron oxide: between 0.5 and 15%, preferably between 3 and 12%, other oxide(s): between 0 and 5% cumulative, preferably less than 3%, the remainder being made up of unavoidable impurities,

Apart from the mineral fibres, the insulating material used according to the invention contains a binder containing at least one thermoset resin, i.e. a crosslinked, insoluble and infusible polymer system. The binder can be obtained by hardening a sizing composition, which consists of an aqueous solution suitable for being sprayed onto 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.

In one embodiment of the invention, the thermoset resin is a phenolic resin.

The phenolic resins usable according to the present invention include both novolac resins and resols, both of which are obtained by reaction of formaldehyde, and optionally another aldehyde, with phenol and optionally o-, p- and/or m-cresol.

Resols are prepared using excess formaldehyde under basic conditions, with the formaldehyde/phenol molar ratio typically ranging from 2 to 4, with each phenol molecule potentially reacting with three formaldehyde molecules. They contain numerous methylol functions carried by an aromatic ring, which constitute the sites of crosslinking by dehydration/formaldehyde release. These resins are essentially composed of phenol/formaldehyde (PF) condensates, residual phenol and residual formaldehyde.

Novolac resins, on the other hand, are obtained by acid catalysis, using a substoichiometric amount of formaldehyde. Novolac resins require the use of a crosslinker, such as a polyamine, to form a thermoset resin.

According to the invention, it is preferred to use phenolic resins of the resol type, optionally modified with an amine, preferably a monoalkanolamine, and in particular monoethanolamine.

This alkanolamine reacts according to the Mannich reaction with phenol/formaldehyde (PF) condensates, phenol and formaldehyde to form phenol/formaldehyde/amine (PFA) condensates. This amine phenolic resin consists of essentially phenol-formaldehyde condensates and phenol-formaldehyde-amine condensates. Resins of this type are described in particular in application WO2008/043961.

In another embodiment of the invention, the thermoset resin is the product of the reaction between compounds comprising:

- 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 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 monomeric polycarboxylic acids, generally having a molar mass 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. The tricarboxylic acids are for example chosen from the group formed by 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.

Alternatively, the polycarboxylic acids used in this embodiment of the present invention may be polymeric polycarboxylic acids, generally having a molar mass greater than 1000, such as homopolymers of acrylic, methacrylic, crotonic, isocrotonic, maleic, cinnamic, itaconic, 2-methylmaleic or 2-methylitaconic acid. Examples of anhydrides of these acids are succinic, glutaric, trimellitic, maleic, itaconic, phthalic, tetrahydrophthalic, acrylic and methacrylic anhydrides. Copolymers of these acids or anhydrides with each other and/or with a vinyl comonomer may also be mentioned.

Preferably, the co-reactant used with the abovementioned acids is a saccharide chosen from monosaccharides, disaccharides, oligosaccharides, polysaccharides and their mixtures.

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. Particular mention may be made of starch hydrolysates (including dextrins and glucose syrups), as well as cellulose and/or hemicellulose hydrolysates, in particular hydrolysates of bagasse or sugar cane molasses or beet molasses. The starch itself may be extracted from plants chosen from: vegetables, legumes, fruits and seeds, including 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.

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

In a preferred embodiment of the invention, the thermoset resin is the product of the reaction between said at least one saccharide and said at least one polycarboxylic acid, preferably between at least one hydrogenated sugar and said at least one polycarboxylic acid. Thermosetting resins 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 in the name of the Applicant. It is preferred to use bio-sourced reagents comprising at least 70% by weight, preferably at least 80%, and ideally at least 90% by weight of hydrogenated sugars and citric acid.

Instead of or in addition to a saccharide, at least one alkanolamine may be used as a co-reactant with the abovementioned polycarboxylic acids or their anhydrides. As binders based on these acids and alkanolamines, mention may be made in particular of those comprising 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. These binders are notably described in applications W02004/007615 and W02006/0061249.

Examples of polyols (other than hydrogenated sugars) used as co-reactants with the acids described above 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.

Other co-reactants include polyamines such as diethylenetriamine, triethylenetetramine or tetraethylenepentamine. Acid-based binders polycarboxylic and polyamine compounds are notably described in US application 2007/0173588.

In another embodiment of the invention, the thermoset resin is 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 case in particular where the saccharide comprises a reducing sugar, for example glucose or xylose, preferably glucose, at least one co-reactant chosen from 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.

Constituents other than those mentioned above may also be present in the binder. They may be derived from the sizing composition or from the reaction between components of the sizing composition and at least one of the co-reactants described above and/or produced by heating components of the sizing composition. The sizing composition may in fact comprise at least one component chosen from: water; 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 (such as 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; and mixtures thereof.

In the method according to the present invention, an insulating material 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, /sobutylamine, tert-butylamine, pentylamine, hexylamine, tert-octylamine, cyclohexylamine, isophorylamine, benzylamine (aniline), xylylamine, tolylamine, aminoethanol, aminopropanol, and mixtures thereof.

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, N-(2-aminoethyl)-1,3-propanediamine, benzidine, N,N'-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.

According to the invention, it is preferred to use a monoamine, in particular aminopropanol.

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

The insulating material 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 gaseous phase, by passing the amine into a container containing the material and, in the case where the amine is in the liquid phase, by dipping, spraying or coating, preferably by immersing the insulating material 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 insulating material may be brought into contact with the amine 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 1 hour to 48 hours, preferably from 2 hours to 30 hours.

The method according to the invention may further comprise steps of recovering the material 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 an insulating material, optionally after carding.

The reaction product is then washed with water and dried to recover the fibers which can be reused in the manufacture of a new insulating material, possibly after a carding step. FIGURES

[Fig 1] shows the evolution of the appearance of a sample of glass wool containing a binder based on phenolic resin, after hydrolysis (water) or aminolysis (ethylene diamine).

[Fig 2] illustrates the results of mechanical tests carried out on a sample of glass cloth containing a phenolic resin binder, before and after aminolysis.

[Fig 3] illustrates the results of mechanical tests carried out on a sample of glass cloth containing a polyester-based binder, before and after aminolysis.

[Fig 4] shows the evolution of the appearance of a sample of glass wool, containing a binder based on Maillard reagents, after aminolysis (3-amino-l-propanol).

[Fig 5] illustrates the results of mechanical tests carried out on a sample of glass cloth containing a binder based on saccharide and ammonium salt of inorganic acid, and after aminolysis.

[Fig 6] illustrates the variation in appearance and diameter of a glass fiber subjected to an aminolysis process.

EXAMPLES

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

EXAMPLE 1: Decomposition of a phenolic resin binder

Tests were carried out on a glass wool sample comprising biosoluble glass fibres and a phenolic resin binder as described in patent application WO2008/043961. Approximately 2 g of this sample were placed in a flask and covered with 55 g of ethylene diamine which was refluxed (130°C) for approximately 24 h. For comparison, another identical sample was placed in refluxing water (100°C) for approximately 24 h. After 24 h, the samples were washed with water and dried by vacuum filtration. Photographs of the treated and untreated samples are shown in Figure 1. As can be seen from this figure, the sample treated by aminolysis appears whiter, as a result of the decomposition of the phenolic resin which gave it an initial yellow appearance. In contrast, the sample treated by hydrolysis remains yellow-orange, suggesting that hydrolysis is not sufficient to decompose the binder. Scanning electron microscope (SEM) analysis also observed that the hydrolyzed sample still shows traces of binder between the fibers, identified by a circle, while no binder was identified between the fibers treated by aminolysis, which appear disentangled. To confirm these observations, a tensile test was performed on samples treated by aminolysis, on the one hand, and untreated, on the other hand. To do this, a test specimen was taken from a sample of glass cloth coated with the binder described above, then the test specimen was suspended from an aluminum rod in a reactor in which the amine was refluxed. After aminolysis, the test specimen was dried and then subjected to a tensile test carried out at 1 mm/min on a Shimadzu EZ LX tensile bench with an ION force sensor. The same test was performed on untreated test specimens taken from the same sample.

As shown in Figure 2, the force required to separate the fibers was very low, reflecting sliding of the fibers past each other. The breaking stress and Young's modulus of the treated sample were also very low.

EXAMPLE 2: Decomposition of a polyester-based binder

A tensile test identical to that described in Example 1 was carried out on a sample of glass wool comprising glass fibres and a polyester-based binder resulting from the reaction of citric acid with sugars as described in patent application WO2013/014399, respectively subjected to an aminolysis process or not().

The results of the tensile test performed are shown in Figure 3.

As can be seen from this Figure, the force required to separate the glass fibers is very low, reflecting degradation of the polyester binder. The breaking stress and Young's modulus of the treated sample were also very low.

EXAMPLE 3: Decomposition of a binder based on Maillard reagents

Tests were carried out on glass wool comprising glass fibres and a binder of plant origin (Ecose* from KNAUF) comprising a thermoset resin prepared by Maillard reaction between a saccharide and an amino compound. A sample of approximately 2 g was placed in a flask and covered with 55 g of aminopropanol which was refluxed (185°C) for approximately 24 h. After 24 h, the sample was washed with water and dried by vacuum filtration. A photograph of the treated sample is shown in Figure 4. As can be seen from this figure, aminolysis made the sample whiter, due to the decomposition of the products of the Maillard reaction which gave it an initial brown appearance.

Further tests were carried out by replacing the aminopropanol with ethylene diamine, on the one hand, and the glass fibres with rock fibres, on the other hand: the same observations could be made. EXAMPLE 4: Decomposition of a binder based on sucrose and ammonium salt of inorganic acid

A tensile test was carried out on a specimen from a glass wool sample comprising a self-crosslinked sugar-based binder, resulting from the reaction of sucrose with ammonium sulfate, in a sucrose/ammonium sulfate ratio of 85/15.

The conditions of the test described in Example 1 were modified so as to subject the sample to aminolysis using aminopropanol vapors and not by immersion in diethylamine. To do this, a small amount of amine was placed at the bottom of a flask above which the sample was suspended using a wire. The strain/stress curves obtained are shown in Figure 5. As shown in this Figure, the specimen exhibits no mechanical resistance after aminolysis, which reflects the effectiveness of this treatment in breaking down the binder tested. The breaking stress and Young's modulus of the treated sample were also very low.

EXAMPLE 5: Decomposition of a binder based on poly(furfuryl alcohol)

A glass wool sample comprising a binder based on poly(furfuryl alcohol) derived from sugarcane bagasse (Biorez® from TransFuran Chemical) and high alumina glass fibers was used.

Approximately 2 g of this sample were immersed in a flask containing aminopropanol which was refluxed for approximately 24 h. Photographs of the sample were taken before and after treatment: a change in the color of the sample was observed which highlighted the degradation of the binder.

EXAMPLE 6: Evaluation of the preservation of fiber quality

The impact of aminolysis treatment on fiber quality was evaluated using glass fibers and high alumina (HA) fibers, respectively.

To do this, glass fibers as described in W02005/033032, approximately 500-600 pm in diameter and 4 cm in length, were immersed in refluxing ethylenediamine for 24 h. The general appearance of the fibers before and after treatment was observed and their average diameter was measured: no changes were observed.

THA fibers were subjected to aminolysis treatment using aminopropanol in which they were partially immersed, in order to simultaneously evaluate the effect of liquid and gaseous aminopropanol. Fiber diameter was measured before and after treatment. It was observed that the diameter of the immersed part of the fiber, subjected to liquid aminopropanol, had decreased by 5% during the aminolysis treatment. On the contrary, the diameter of the emerged fiber part, treated with aminopropanol vapors, was unchanged. This example thus demonstrates that vapor phase aminolysis preserves fiber quality better than liquid phase aminolysis. It is thus possible to reuse the fibers in the manufacture of a new glass wool product.

Claims

Claims 1. A method of recycling an insulating material in the form of a mineral wool mattress or felt containing mineral fibres which represent from 80 to 99% of the weight of the insulating material and a binder comprising at least one thermoset resin, said method comprising a step of placing said insulating material 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 phenolic resin optionally modified with an amine, in particular an amino phenolic resin consisting essentially of phenol-formaldehyde condensates and phenol-formaldehyde-amine condensates. 3. Method according to claim 1, characterized in that the binder comprises the product of the reaction between compounds comprising: - 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, or an anhydride of such an acid. 4. Method according to claim 3, characterized in that the binder is the product of the reaction of said at least one polycarboxylic acid with a co-reactant chosen from: at least one saccharide chosen from monosaccharides, disaccharides, oligosaccharides, polysaccharides and their mixtures; at least one alkanolamine; at least one polyol other than a saccharide; at least one polyamine; and their mixtures, preferably the binder is the product of the reaction between said at least one saccharide and said at least one polycarboxylic acid, more preferably between at least one hydrogenated sugar and said at least one polycarboxylic acid. 5. Method according to claim 3 or 4, characterized in that the polycarboxylic acid is a monomeric acid or a polymeric acid, preferably a monomeric acid, more preferably citric acid. 6. Method according to claim 3, characterized in that the saccharide is a reducing sugar and the binder is the product of the reaction of said at least one saccharide with at least one co-reactant. chosen from: 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. 7. Method according to claim 6, characterized in that the reducing sugar is chosen from glucose and xylose, preferably glucose. 8. Process according to any one of claims 1 to 7, 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 carbon atoms and may optionally be substituted by at least one hydroxyl group and/or interrupted by at least one oxygen atom; and mixtures thereof. 9. Method according to any one of claims 1 to 8, characterized in that the contacting of the insulating material and the amine is carried out by immersion of the insulating material in a solution containing, or consisting of, the amine, preferably at the boiling temperature of the amine. 10. Method according to any one of claims 1 to 8, characterized in that the amine is in gaseous form and the contacting of the insulating material and the amine is preferably carried out by passing the amine into a container containing the insulating material. 11. Method according to any one of claims 1 to 10, characterized in that it further comprises steps of recovering the material treated with the amine, washing, preferably with water or with an aqueous solution, and drying, in order to obtain mineral fibers. 12. Method according to claim 11, characterized in that the recovered mineral fibers are reused in the manufacture of an insulating material, possibly after carding. 13. Use of an amine as defined in claim 1 or 8 to decompose the binder contained in an insulating material in the form of a mattress or mineral wool felt containing mineral fibers which represent from 80 to 99% of the weight of the insulating material and a binder comprising at least one thermoset resin.