Method for producing an insulating article based on inorganic fibers or organic fibers of natural origin

Abstract

The present invention relates to a method for making an insulation article comprising inorganic or natural organic fibers bound by an organic binder, the method comprising the steps of: (a) applying a sizing composition to the inorganic fibers or the natural organic fibers; (b) forming an aggregate of said inorganic fibers or said natural organic fibers; (c) heating the collection of inorganic fibers or natural organic fibers until the sizing composition cures; 5, wherein the sizing composition comprises: at least one lignin, which is potentially oxidized; and at least one non-polymeric organic polycarboxylic acid, The present invention is characterized by comprising: The invention also relates to insulation articles obtainable by such a method.

Description

[Technical Field]

[0001] The present invention relates to a method for producing an insulation article comprising inorganic or natural organic fibers bound by an organic binder obtained by curing or crosslinking a sizing composition containing potentially oxidized lignin and a non-polymeric polycarboxylic organic acid. The present invention also relates to an insulation article obtained by such a method. [Background technology]

[0002] The production of insulation articles based on inorganic fibers, particularly mineral wool, generally involves producing glass or rock fibers through a centrifugation process. In their path between the centrifuge and the fiber collection belt, an aqueous sizing composition, also called an aqueous binder composition, is sprayed onto the fibers while they are still hot, and the composition then undergoes a polymerization reaction, generally at temperatures above 100°C.

[0003] For several years, the use of various thermosetting resins as binders in sizing compositions has made it possible to bond the inorganic fibers and improve the mechanical performance of the resulting insulation articles. The thermosetting resins most commonly used in the manufacture of mineral wool-based insulation articles are resol-type phenolic resins. In addition to their good crosslinking ability under the aforementioned thermal conditions, these resins are water-soluble, have good compatibility with inorganic fibers, especially thanks to the presence of silanes, and are relatively inexpensive.

[0004] The most common resoles are obtained by condensation of phenol and formaldehyde in the presence of a basic catalyst. Finally, these resoles contain a proportion of unreacted monomers, especially formaldehyde, the presence of which is undesirable in view of known harmful effects.

[0005] For this reason, resole-based resins are generally treated with urea, which reacts with free formaldehyde and traps it in the form of non-volatile urea-formaldehyde condensates. Furthermore, the presence of urea in the resin offers certain economic advantages due to its low cost; it can be incorporated in relatively large amounts without affecting the use qualities of the resin, particularly without adversely affecting the mechanical performance of the final article, which can significantly reduce the overall cost of the resin.

[0006] Nevertheless, it has been observed that under the temperature conditions to which the mineral wool layer is subjected to obtain cross-linking of the resin, urea-formaldehyde condensates are unstable; they decompose to give formaldehyde and urea again, the latter of which is at least partially decomposed into ammonia and released into the atmosphere of the plant, which must be subjected to recovery procedures to reduce its impact on the environment. Therefore, solutions have been developed to replace formaldehyde-based resins in sizing compositions.

[0007] The applicant has proposed in their WO 2010 / 029266 and WO 2013 / 014399 sizing compositions based on hydrogenated sugars, also known as sugar alcohols, for binding inorganic fibers. These agents have very good thermal stability and impart good mechanical performance to the final article.

[0008] Formaldehyde-free binders containing hydrogenated sugars and both reducing and non-reducing sugars have been disclosed in WO 2013 / 021112 and WO 2015 / 159012, respectively, in the name of the applicant, for binding inorganic fibers. However, these sugar-based resins show little reactivity and stability for binding natural organic fibers.

[0009] For binding natural organic fibers, especially those with a density of 250 kg / m 3It is known to use binders obtained after curing or crosslinking of sizing compositions containing polyisocyanates to obtain insulating articles having a viscosity of less than 100 MPa. Among the polyisocyanates most commonly used in the wood fiber industry, mention may be made of poly(methylene diphenyl isocyanate) (pMDI, CAS number 9016-87-9), which is a technical grade blend containing 30 to 80% of MDI (methylene diphenyl isocyanate) and higher molecular weight homologues of the formula:

[0010] [ka]

[0011] To ensure good wetting of natural organic fibers by hydrophobic pMDI, it is generally necessary to first subject the fibers to drying, thereby reducing their moisture content to a value below 6% by weight, in particular between 2 and 6% by weight (see WO 2008 / 144770).

[0012] A relatively recent proposal is emulsifiable pMDI (EMDI), which is a mixture of pMDI with non-ionic surfactants that do not contain labile hydrogens that can react with isocyanate functional groups (see, for example, EP-A-0 516 361), or a mixture of pMDI with a small proportion of pMDI that has been functionalized with hydrophilic chains, such as polyethoxylated chains, to stabilize the emulsion.

[0013] The use of pMDI in the form of an aqueous emulsion makes it possible to distribute the binder evenly on the natural organic fibers without pre-drying, which constitutes a significant energy saving.

[0014] However, the use of polyisocyanate-based binders, even in the form of aqueous pMDI emulsions, constitutes a major problem in terms of hazards at the board manufacturing site due to the presence of polyisocyanates. Furthermore, polyisocyanates are highly reactive and expensive raw materials. Summary of the Invention [Problem to be solved by the invention]

[0015] Therefore, the applicant has sought a method for producing both inorganic fiber-based and natural organic fiber-based insulation articles using the same type of organic binder, i.e., the same sizing composition, which will be capable of binding both inorganic and natural organic fibers after curing; such a sizing composition should preferably be of bio-based origin, have low toxicity, low cost, have good cross-linking ability, be capable of being uniformly dispersed across any of the aforementioned fibers, and allow insulation articles with good mechanical properties to be obtained. Furthermore, the desired sizing composition should have the advantage of not polymerizing / cross-linking or only slightly polymerizing / cross-linking before passing through a suitable heating device, and / or polymerizing / cross-linking rapidly upon passing through a suitable heating device. [Means for solving the problem]

[0016] During the course of this research, the inventors discovered that a sizing composition comprising a particular combination of the following provides the desired benefits or properties: - at least one lignin, which is potentially oxidized, and at least one non-polymeric organic polycarboxylic acid;

[0017] The object of the present invention is therefore more precisely a method for the manufacture of an insulating article comprising inorganic or natural organic fibers bound by an organic binder, comprising the following steps: (a) applying a sizing composition to the inorganic fibers or the natural organic fibers; (b) forming an aggregate of the inorganic fibers or the natural organic fibers; (c) heating the inorganic fibers or the collection of natural organic fibers until the sizing composition cures; 10. The method of claim 1, wherein the sizing composition comprises: - at least one lignin, which is potentially oxidized, and at least one non-polymeric organic polycarboxylic acid; [Brief explanation of the drawings]

[0018] [Figure 1] Figure 1 shows the possible structure of native lignin.

[0019] [Figure 2] FIG. 2 shows a possible structure of lignin according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0020] The lignin of the present invention is extracted from so-called "native" lignin, a biomolecule belonging to the group of polyphenolic polymers (broadly the group of tannins), which, together with cellulose and hemicellulose, are one of the main components of wood. Figure 1 shows a possible structure of native lignin. Native lignin has a molar mass of 10,000 g / mol. -1It is a polymer significantly larger than 1000 kJ / cm and is insoluble in water. Native lignin is found primarily in vascular plants and some algae. Its main function is to provide rigidity, waterproofing, and high resistance to decomposition. All vascular plants, whether woody or herbaceous, produce lignin. Quantitatively, the native lignin content is 3-5% in leaves, 17-24% in herbaceous stems, and 18-33% in woody stems (18-25% in broad-leaved angiosperms and 27-33% in conifers). It is relatively less abundant in annual plants than in perennials, but is very abundant in trees. Native lignin is primarily present between cells, but significant amounts are also present within them. Lignin is a complex three-dimensional hydrophobic network, but its basic unit is essentially a monolignolic unit. After cellulose (which constitutes 35–50% of terrestrial plant biomass) and hemicellulose (30–45%), lignin (15–25%) is the third most abundant group of compounds in plant and terrestrial ecosystems, dominated by dead and living plant biomass.

[0021] The lignin according to the invention is a polymer, one possible structure of which is shown in Figure 2. The lignin according to the invention is extracted by cleavage of the β-O-4 ether bonds of native lignin and therefore has a lower molar mass than the native lignin from which it is derived, i.e., 10,000 g mol -1 Average molar mass less than 1,000 g mol -1 ~9,000 g mol -1 It has a molar mass of

[0022] The lignin according to the present invention can be selected from alkaline lignin, also known as kraft lignin, lignosulfonate, organic solvent lignin, sodium lignin, lignin from biorefining processes of lignocellulosic feedstocks, or mixtures thereof. Four groups of commercially available lignins are alkaline lignin, or kraft lignin, lignosulfonate, and organic solvent lignin (extracted lignin and sodium lignin). The fifth group, so-called biorefinery lignin, is slightly different in that it is not described by its extraction method but by the origin of the method, e.g., biorefining, and therefore can be similar or different from any of the other groups mentioned. The lignin according to the present invention is preferably alkaline lignin, also known as kraft lignin.

[0023] Figure 2 shows a possible structure of a lignin according to the present invention. The reactive functional groups present in large amounts in typical lignins are hydroxyl groups, either aromatic or aliphatic, which may be primary or secondary alcohol functional groups (secondary alcohol functional groups are less reactive than primary alcohol functional groups). It is known that the hydroxyl groups of lignin can react with crosslinking agents, such as isocyanates, epoxides, amines, or aldehydes, thereby resulting in crosslinked lignin structures according to various crosslinking mechanisms. However, these crosslinking agents have not received much attention due to their toxicity (isocyanates, amines, formaldehyde) and / or cost (epoxides, amines, aldehydes but not formaldehyde).

[0024] The present inventors have now discovered that non-polymeric polycarboxylic acids, which are themselves of low toxicity, can crosslink lignin, and further discovered that these non-polymeric polycarboxylic acids can be used as lignin crosslinkers to bond both inorganic and natural organic fibers after curing or crosslinking of these components, resulting in insulation articles with mechanical performance that is as good or even relatively better than that achieved using other known crosslinkers, such as formaldehyde or isocyanates.

[0025] In this application, the term "non-polymeric" organic polycarboxylic acids refers to polycarboxylic acids having a molar mass of 90 g mol-1 or more, which are linked in a repeating manner by covalent bonds. -1 ~350 g mol -1 Therefore, in the present application, the sizing composition preferably does not comprise a polymeric organic polycarboxylic acid. The non-polymeric organic polycarboxylic acids according to the invention may be selected from dicarboxylic acids, in particular 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 and derivatives thereof, in particular those containing at least one boron or chlorine atom, tetrahydrophthalic acid and derivatives thereof, in particular those containing at least one chlorine atom, isophthalic acid, terephthalic acid, mesaconic acid and citraconic acid, tricarboxylic acids, in particular citric acid, tricarballylic acid, 1,2,4-butanetricarboxylic acid, aconitic acid, hemimellitic acid, trimellitic acid and trimesic acid; and tetracarboxylic acids, in particular 1,2,3,4-butanetetracarboxylic acid and pyromellitic acid. Even more preferably, the non-polymeric organic polycarboxylic acid is selected from maleic acid, succinic acid, glutaric acid, itaconic acid, and citric acid.More preferably, the non-polymeric organic polycarboxylic acid is a tricarboxylic acid, especially citric acid.

[0026] In other words, it has been surprisingly discovered by the present inventors that lignin, an inexpensive, non-toxic, and low-corrosion biologically-derived material, in combination with low-toxicity non-polymeric organic polycarboxylic acids, can bind inorganic or natural organic fibers after curing or crosslinking of these components; and can enable the production of insulation articles having mechanical properties comparable to, or even better than, the known binders mentioned above.

[0027] In one embodiment of the present invention, prior to adding the non-polymeric organic polycarboxylic acid, the lignin is diluted with water and the pH adjusted to 6.5 to 10.5, preferably 8 to 9. This pH range has the advantage of allowing for a relatively uniform deposition of the sizing composition onto the fibers, thereby improving the mechanical properties of the resulting insulation article.

[0028] Preferably, the sizing composition comprises from 25% to 85% by weight, more preferentially from 40% to 80% by weight, and even more advantageously from 50% to 75% by weight of at least one lignin, based on the total dry weight of the composition.

[0029] Preferably, the sizing composition comprises from 15% to 75% by weight, more preferentially from 20% to 60% by weight, and even more advantageously from 25% to 50% by weight of at least one non-polymeric organic polycarboxylic acid, based on the total dry weight of the composition.

[0030] In another preferred embodiment of the method of the present invention, the lignin contained in the sizing composition in combination with the non-polymeric organic polycarboxylic acid is oxidized lignin. In this embodiment, the amount of oxidized lignin is 50% to 85% by weight, preferably 55% to 80% by weight, and more preferentially 60% to 75% by weight, based on the total dry weight of the sizing composition. The oxidized lignin contains 2% to 20%, preferably 5% to 15% of carboxylic acid functional groups and 2% to 20%, preferably 5% to 15% of primary alcohol functional groups. The proportions of carboxylic acid functional groups and primary alcohol functional groups present on the oxidized lignin are measured by infrared spectroscopy by calculating the ratio of the intensity of the peak of the C-O bond of the carboxylic acid functional groups (C-OOH) of the oxidized lignin to the intensity of the peak of the C-O bond of the primary alcohol functional groups (C-OH) of the oxidized lignin, respectively, compared to the sum of the intensities of the peaks of the C-O bonds of all functional groups present on the oxidized lignin. All peaks are within the range of 1000 cm. -1~ ~1300cm -1 All functional groups present on oxidized lignin with C-O bonds are as follows: primary and secondary alcohol functional groups (C-OH); aromatic hydroxyl functional groups (Ar-OH), acid functional groups (C-OOH); aromatic ether functional groups (Ar-OC), aliphatic and cycloaliphatic ether functional groups (C-OC), and methyl ether functional groups (C-OCH).

[0031] The use of oxidized lignin (compared to unoxidized lignin) has the advantage of reducing the amount of non-polymeric organic polycarboxylic acid added to the sizing composition to bind the inorganic or organic fibers. Thus, in this particular embodiment, the amount of non-polymeric organic polycarboxylic acid is 15% to 50% by weight, preferably 20% to 45% by weight, and more preferentially 25% to 40% by weight, based on the total dry weight of the sizing composition.

[0032] Indeed, in a sizing composition comprising a combination of at least one oxidized lignin and at least one non-polymeric organic polycarboxylic acid, the carboxylic acid groups present on the oxidized lignin obtained by splitting the polymer and then oxidizing the secondary aliphatic hydroxyl groups of the starting lignin will react with some of the aliphatic hydroxyl groups of the oxidized lignin (in particular the primary alcohol functional groups) during the heating stage of the fiber assembly, thereby initiating self-crosslinking of the oxidized lignin, and then other aliphatic hydroxyl groups of the remaining oxidized lignin will react with the carboxylic acid groups of the non-polymeric organic polycarboxylic acid added as a crosslinking agent to complete the crosslinking of said oxidized lignin.

[0033] Furthermore, the sizing composition according to the present invention may be formaldehyde-free. In the present application, "formaldehyde-free" is understood to mean that the formaldehyde content in the sizing composition according to the present invention is less than 2000 ppm.

[0034] The sizing composition is an aqueous composition which may have a dry matter content of between 0.5% and 50% by weight, preferably between 3% and 30% by weight and more preferentially between 4% and 20% by weight.

[0035] The aqueous sizing composition is then applied to the inorganic or natural organic fibers in an amount of 2% to 20% by weight, preferably 5% to 15% by weight, expressed as dry matter based on the weight of the inorganic or natural organic fibers, to impart the desired mechanical properties to the insulation article.

[0036] In a preferred embodiment of the method of the invention, step (a) of applying the sizing composition to the inorganic or natural organic fibers can be carried out by spraying, in particular by means of a spray nozzle, or by roller coating, or by impregnation.

[0037] According to the invention, the inorganic fibers are preferentially mineral wool, and even more preferentially glass wool, rock wool or slag wool, or mixtures thereof. In particular, when the inorganic fibers are mineral wool, they may contain a composition corresponding, in weight percentages, to the following formula: SiO2: 30 to 50%, preferably 35 to 45%, Na2O: 0 to 10%, preferably 0.4 to 7%, CaO: 10 to 35%, preferably 12 to 25%, MgO: 1 to 15%, preferably 5 to 13%, CaO+MgO: 11-40% in total, Al2O3: 10-27% K2O: 0 to 2%, preferably 0 to 1%, Iron oxide: 0.5 to 15%, preferably 3 to 12%, One or more other oxides: 0 to 5% in total, preferably less than 3%; The remainder is made up of inevitable impurities.

[0038] The inorganic fibers may be glass fibers or rock fibers, in particular basalt (or wollastonite). More particularly, the inorganic fibers according to the invention are fibers of aluminosilicate glass, in particular aluminosilicate glass fibers containing aluminum oxide Al2O3 in a proportion of 14% to 28% by weight. In another embodiment, the inorganic fibers may be glass fibers containing a composition, in weight percentages, corresponding to the following formula: SiO2: 50 to 75%, preferably 60 to 70%, Na2O: 10 to 25%, preferably 10 to 20%, CaO: 5 to 15%, preferably 5 to 10%, MgO: 1 to 10%, preferably 2 to 5%, CaO and MgO in total are preferably 5 to 20%, B2O3: 0 to 10%, preferably 2 to 8%, Al2O3: 0 to 8%, preferably 1 to 6%, K2O: 0 to 5%, preferably 0.5 to 2%, The total amount of Na2O and K2O is preferably 12 to 20%, Iron oxide: 0 to 3%, preferably less than 2%, even more preferably less than 1%; one or more other oxides: 0 to 5% by weight in total, preferably less than 3% in total; The remainder is made up of inevitable impurities.

[0039] The diameter of the inorganic fibers is advantageously between 0.1 and 25 μm.

[0040] The diameter of the natural organic fibers is advantageously between 5 and 100 μm, preferably between 10 and 50 μm, and the length of these fibers is in particular between 0.1 and 900 mm, more particularly between 10 and 120 mm. According to the invention, the natural organic fibers are advantageously non-thermoplastic fibers, fibers that occur naturally in biomass and may have undergone mechanical and / or chemical treatment. These fibers are derived from plant sources and are advantageously selected from cotton and lignocellulosic fibers. Lignocellulosic fibers are understood to mean fibers of plant origin based on lignocellulosic materials, i.e., fibers containing cellulose, hemicellulose, and lignin. Lignocellulosic fibers include wood fibers and fibers of other plant origin, such as hemp, flax, sisal, cotton, jute, coconut, raffia, abaca fibers, or even cereal or rice straw.

[0041] The term "lignocellulosic fiber" as used herein does not include lignocellulosic materials that have undergone thermomechanical or chemical processing for the production of paper pulp.

[0042] Thus, the lignocellulosic fibers used in the present invention have been subjected to a mechanical comminution process intended solely to reduce and / or control the size of the fibers.

[0043] The lignocellulosic fibers are preferably coniferous, in particular pine, fibers obtained by mechanical fiberization, their diameter advantageously ranging from 10 to 70 μm, preferably from 30 to 50 μm, and their length ranging from 0.1 to 100 mm, preferably from 0.5 to 50 mm, in particular from 1 to 10 mm.

[0044] The application of the sizing composition (a) preferably occurs before step (b) of forming a mass of inorganic or natural organic fibers, in which the sized fibers are brought together and then heated, either continuously or temporarily, to cure the sizing composition and thus form an organic binder that binds the fibers together.

[0045] Therefore, step (b) of forming an aggregate of inorganic or natural organic fibers may also be referred to as a step of shaping a set of fibers, and may be carried out by molding and / or compression. The mold used to form the article must be made of a material that can withstand the temperature of the heating step. It must also have a structure that allows hot air from the curing oven to easily penetrate the molded article. The mold may, for example, consist of a box-shaped metal screen. The metal screen box is filled with loose fibers, preferably in a volume greater than its capacity, and then closed with a metal screen cover. In this way, the fibers are more or less compressed depending on the amount of overfilling. This amount of overfilling of the box with fibers may be, for example, 10% to 150%, preferably 15% to 100%, and particularly 20% to 80%.

[0046] When the process of the present invention is a continuous process, step (b) of forming a mass of fibers can be carried out by compression, for example, by rollers located at the entrance of the curing oven on a conveyor.

[0047] Additionally, the fibers may be assembled as follows: - flexible fiber mats that can be rolled, compressed or folded; - fibreboard or plate, which is denser and more rigid than rollable mats; - fiber-based molded articles, such as pipe or duct linings, - Woven or nonwoven fabrics, such as nonwoven mats made of glass fibre or organic fibres.

[0048] In a particular embodiment of the method according to the present invention, the fibers are natural organic fibers impregnated with an aqueous sizing composition, and the method further comprises a fiber drying step between steps (a) and (b) to evaporate sufficient water to render the sized or unsized fibers substantially tack-free. In another embodiment, the drying step can be carried out before step (a). This drying step can be carried out by heating, for example, in a temperature-controlled ventilated oven, or alternatively by using a steam-heated press. It is important not to heat the natural organic fibers to an excessively high temperature during drying, which would soften the dried sizing composition or even initiate crosslinking of the components of the sizing composition. Heating temperatures close to the boiling point of water are generally sufficient. Thus, drying of the fibers impregnated with the aqueous sizing composition is preferably carried out by heating to a temperature of 75°C to 150°C for a time of 1 to 10 seconds. The natural organic fibers obtained after the drying step are surrounded by a sheath of the dried sizing composition.

[0049] Step (c) of heating the aggregate of inorganic or natural organic fibers according to the method of the present invention is preferably carried out in a temperature-controlled vessel or steam press at a temperature of 100°C to 250°C for a time period of 1 minute to 20 minutes. The temperature-controlled vessel may be a forced air oven or a heated mold with fluid circulation or resistance heating, into which temperature-controlled hot gas is introduced in one or more compartments. During this step of heating the aggregate of inorganic or natural organic fibers, the components of the sizing composition (according to the present invention) cure and / or crosslink / polymerize to form an insoluble organic binder.

[0050] In another specific embodiment of the method according to the present invention, the fibers are inorganic fibers, and after step (c) of heating the aggregate of inorganic fibers until the sizing composition cures, the aggregate of inorganic fibers has a loss on ignition (LOI) of 1 wt % to 20 wt %, preferably 1 wt % to 15 wt %.

[0051] The present invention also relates to an insulation article obtainable by the method described above. The resulting insulation article comprises inorganic or natural organic fibers bound with a binder obtained by curing or crosslinking a sizing composition (as described above) comprising optionally oxidized lignin and a non-polymeric organic polycarboxylic acid. The resulting insulation article has good mechanical properties. The insulation article has a thickness of 10 to 300 mm, preferably 35 to 240 mm, and a strength of 30 to 200 kg / m, measured according to EN 823:2013. 3 , preferably 35 to 180 kg / m 3 The resulting insulation article may be used to make exterior insulation panels for buildings. The resulting insulation article may be, inter alia, an inorganic fiber net, especially a glass fiber or rock fiber net. [Example]

[0052] Example 1:

[0053] An aqueous sizing composition is formed containing the ingredients listed in Table 1, each expressed as a weight percent based on the total dry weight of each composition.

[0054] Composition 1 outside the present invention (i.e., comparative sample) is produced by mixing kraft lignin A with water. Compositions 2-4 according to the present invention are produced by mixing a first solution containing lignin A dissolved in water with a second solution containing a specific non-polymeric organic carboxylic acid dissolved in water. Compositions 5 and 5bis outside the present invention (i.e., comparative sample) are produced by successively adding 48 parts by weight of maltitol (as hydrogenated sugar), 52 parts by weight of citric acid, and 5 parts by weight of sodium hypophosphite (catalyst) to a vessel with vigorous stirring until the ingredients are completely dissolved.

[0055] All sizing compositions 1-5 and 5bis contain 90% by weight water and 10% by weight dry matter. All compositions are used to form glass fiber based insulation articles.

[0056] Two laminated pieces of nonwoven glass fiber paper (60 mm x 10 mm x 0.250 mm) were impregnated with each aqueous sizing composition, and the impregnated glass fiber paper was then cured at a temperature of 150°C for 4 minutes (for Samples 1 to 5) or at a temperature of 210°C for 10 minutes (for Sample 5bis).

[0057] The storage modulus of the samples is measured by dynamic mechanical thermal analysis (DMTA) using a TA Instruments RSA-G2 analyzer instrument using a three-point bending test upon cure.

[0058] The operating parameters of the measuring device are as follows: Temperature: 25℃, Poisson's ratio: 0.45, Duration of vibration mechanical stress: 120 seconds, Oscillation frequency: 1.0Hz, Deformation: 0.1%, Sampling rate: 10 points / second.

[0059] Table 1 below shows the storage modulus of the glass fiber paper obtained after curing each sizing composition. Each storage modulus value is the calculated average of two to four individual measurements.

[0060] result

[0061] [Table 1]

[0062] It can be seen that the glass fiber papers produced in accordance with the present invention, i.e., using sizing compositions 2-4 containing a combination of lignin A and a non-polymeric organic polycarboxylic acid, exhibit a higher storage modulus (1.18 GPa to 2.74 GPa) than the glass fiber paper produced using sizing composition 1 (0.92 GPa) containing only lignin (i.e., no crosslinker). Furthermore, a relatively high storage modulus is obtained for the insulation article produced using the sizing composition containing lignin A and citric acid (composition 4). It can also be seen that the glass fiber papers produced in accordance with the present invention (compositions 2-4) exhibit the following: a storage modulus higher than that of glass fiber paper obtained using known thermosetting resins, such as those based on hydrogenated sugars (composition 5, comparative example), or - Storage modulus comparable to that of glass fiber paper obtained with hydrogen sugar-based resin (see comparative example 5bis) when the temperature and duration of the curing process are increased.

[0063] Aqueous sizing compositions are formed containing the ingredients listed in Table 2, each expressed as a weight percent based on the total dry weight of each composition.

[0064] Composition 6 (comparative) is produced by emulsifying emulsifiable poly(methylene diphenyl isocyanate) (pMDI) with water. Compositions 7 and 8 according to the invention are produced by mixing a first solution containing lignin A dissolved in water with a second solution containing succinic acid dissolved in water. Composition 9 (comparative) is produced by mixing a first solution containing lignin A dissolved in water with a second solution containing ethylene glycol diglycidyl ether (epoxide) dissolved in water.

[0065] Sizing composition 6 contains 40% by weight of water and 60% by weight of dry matter, and sizing compositions 7 to 9 contain 90% by weight of water and 10% by weight of dry matter.

[0066] For each test, the wood fibers were impregnated with the aqueous sizing compositions. The amounts of aqueous sizing compositions 6, 8, and 9 deposited on the wood fibers were equal to 7% by weight, expressed as dry matter, relative to the weight of the wood fibers. The amount of aqueous sizing composition 7 deposited on the wood fibers was equal to 10% by weight, expressed as dry matter, relative to the weight of the wood fibers.

[0067] The impregnated wood fibers are then uniformly deposited in a steel mold with an open cavity (60 mm x 10 mm x 12 mm). A 60 mm x 10 mm x 10 mm steel bar is placed on top of the wood fibers, and the entire assembly is heated in a thermostatic press at 150 °C and 10 bar pressure for 4 minutes. The mold is then allowed to cool to room temperature, after which a specimen (60 mm x 10 mm x 2 mm) of the formed lignocellulosic fibers is removed.

[0068] The wood fiber test piece obtained in this way has a strength of approximately 180 kg / m 3 It has a density of

[0069] The flexural storage modulus (3-point bending) is determined for each sample by dynamic mechanical thermal analysis (DMTA) using a TA Instruments RSA-G2 analyzer. The sample is first dried in a desiccator under dynamic vacuum (20 mbar) for several hours. The operating parameters of the measuring device are the same as those described above.

[0070] Table 2 below shows the storage modulus of wood fiber samples obtained after curing each sizing composition. Each storage modulus value is an average calculated from 2 to 4 individual measurements.

[0071] result

[0072] [Table 2]

[0073] It can be seen that wood fiber specimens produced in accordance with the present invention, i.e., with sizing composition 8, which includes a combination of lignin and succinic acid (as the lignin crosslinker), have a higher storage modulus (50.6 GPa) than wood fiber specimens produced with sizing composition 9 (comparative example), in which the lignin crosslinker is an epoxide rather than a non-polymeric organic carboxylic acid. Similar storage moduli are obtained for wood fiber specimens produced with known sizing composition 6 and with sizing composition 7 according to the present invention, which has a relatively higher amount of sizing composition on the fiber.

[0074] In conclusion, Tables 1 and 2 show that lignin in combination with non-polymeric organic carboxylic acids can be used to bond both inorganic and natural organic fibers and to obtain insulation articles with mechanical properties comparable to or even better than those obtained using known sizing compositions.

[0075] Example 2:

[0076] Lignin B was collected, and the amount of carboxylic acid functional groups and primary alcohol functional groups present on the lignin was measured by infrared spectroscopy at about 1190 cm -1 The intensity of the C-OOH bond peak of the carboxylic acid functional group located at approximately 1040 cm -1 The intensity of the C-OH bond peak of the primary alcohol functional group located at 1000 cm of all functional groups present on the lignin B was calculated. -1 ~1300cm -1 The total intensity of the C-O bond peaks is determined by measuring the total intensity of the C-O bond peaks located at the C-O bond peaks. All functionalities present on lignin B with C-O bonds are as follows: primary and secondary alcohol functionalities (C-OH); aromatic hydroxyl functionalities (Ar-OH), acid functionalities (C-OOH); aromatic ether functionalities (Ar-OC), aliphatic and cycloaliphatic ether functionalities (C-OC), and methyl ether functionalities (C-OCH).

[0077] The same measurement is then carried out on lignin B, which is first oxidized under the following conditions: in an aqueous solution of pH ≥ 13, using H2O2 + FeCl3 as oxidizing agent, at 95 °C for 120 min. In this case, all functional groups present on oxidized lignin B with C-O bonds are the following: primary and secondary alcohol functional groups (C-OH); aromatic hydroxyl functional groups (Ar-OH), acid functional groups (C-OOH); aromatic ether functional groups (Ar-OC), aliphatic and cycloaliphatic ether functional groups (C-OC), and methyl ether functional groups (C-OCH3).

[0078] Next, two sizing compositions 10 and 11 are produced by mixing lignin B dissolved in water and oxidized lignin B, respectively, with succinic acid dissolved in water. These sizing compositions are deposited onto wood fibers, thereby producing wood fiberboard specimens according to the method described in Example 1. The flexural storage modulus of the resulting wood fiber specimens is measured by dynamic mechanical thermal analysis (DMTA) as described in Example 1.

[0079] Table 3 shows the results obtained for each sizing composition.

[0080] [Table 3]

[0081] It can be seen that using oxidized lignin B, which contains more carboxylic acid functionality than "unoxidized" lignin B (11% for the oxidized lignin compared to less than 1% for the "unoxidized" lignin), reduces the amount of succinic acid added to obtain a sizing composition with a comparable storage modulus in the final insulation article (37.5% for the oxidized lignin compared to 50% for the "unoxidized" lignin).

Claims

1. 1. A method for making an insulation article having inorganic or natural organic fibers bound by an organic binder, comprising the steps of: (a) applying a sizing composition to the inorganic fibers or the natural organic fibers; (b) forming an aggregate of the inorganic fibers or the natural organic fibers; (c) heating the collection of inorganic fibers or natural organic fibers until the sizing composition cures to form the organic binder; wherein the sizing composition comprises: at least one lignin, potentially oxidized, and at least one non-polymeric organic polycarboxylic acid, A method comprising:

2. 10. The method of claim 1, wherein the lignin is selected from alkaline lignin, also known as kraft lignin, lignosulfonates, organosolv lignin, sodium lignin, lignin from biorefining processes of lignocellulosic feedstocks, or mixtures thereof.

3. 3. The method according to claim 1 or 2, wherein the amount of lignin is from 25 to 85% by weight, preferably from 40 to 80% by weight, based on the total dry weight of the sizing composition.

4. The method of claim 3, wherein the amount of non-polymeric organic polycarboxylic acid is from 15 to 75% by weight, preferably from 20 to 60% by weight, based on the total dry weight of the sizing composition.

5. 3. The method of claim 1 or 2, wherein the lignin is oxidized lignin in an amount of 50 to 85% by weight, preferably 55 to 80% by weight, based on the total dry weight of the sizing composition, and the oxidized lignin contains a proportion of carboxylic acid functional groups of 2 to 20%, preferably 5 to 15%, and a proportion of primary alcohol functional groups of 2 to 20%, preferably 5 to 15%.

6. 6. The method of claim 5, wherein the amount of non-polymeric organic polycarboxylic acid is from 15 to 50% by weight, preferably from 20 to 45% by weight, based on the total dry weight of the sizing composition.

7. 3. The method according to claim 1, wherein the non-polymeric organic polycarboxylic acid is selected from dicarboxylic acids, in particular 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 and derivatives thereof, in particular those containing at least one boron or chlorine atom, tetrahydrophthalic acid and derivatives thereof, in particular those containing at least one chlorine atom, isophthalic acid, terephthalic acid, mesaconic acid and citraconic acid, tricarboxylic acids, in particular citric acid, tricarballylic acid, 1,2,4-butanetricarboxylic acid, aconitic acid, hemimellitic acid, trimellitic acid and trimesic acid; and tetracarboxylic acids, in particular 1,2,3,4-butanetetracarboxylic acid and pyromellitic acid.

8. 3. The method according to claim 1 or 2, wherein the inorganic fibers are glass fibers or rock fibers or slag fibers, or a mixture thereof.

9. 3. The method according to claim 1 or 2, wherein the natural organic fibres are selected from fibres from wood, hemp, flax, sisal, cotton, jute, coconut, raffia, abaca fibres or even cereal straw or rice straw.

10. 3. The method of claim 1 or 2, wherein applying the sizing composition of step (a) onto the inorganic or natural organic fibers is carried out by spraying, roller coating, or impregnation.

11. 3. The method of claim 1 or 2, wherein the assembly of inorganic or natural organic fibers in step (b) is a fiber mat, a fiberboard or panel, a fiber-based molded article, or a woven or nonwoven fabric.

12. 3. The method of claim 1 or 2, wherein step (c) comprises heating the collection of fibers, preferably in a temperature-controlled vessel or steam press, at a temperature of from 100°C to 250°C for a time of from 1 minute to 20 minutes.

13. 3. An insulation article obtainable by the method of claim 1 or 2, comprising inorganic or natural organic fibers and an organic binder obtainable by curing a sizing composition comprising at least one potentially oxidized lignin and a non-polymeric organic polycarboxylic acid.

14. 14. The insulating article of claim 13, which is a net of inorganic fibers.