Hydrogenated sugar-based aqueous sizing composition for binding mineral fibers or natural organic fibers

Abstract

The present invention relates to an aqueous sizing composition for binding mineral fibers or natural organic fibers characterized in that it comprises: - at least one hydrogenated sugar; - at least one organic polycarboxylic acid; - at least one salt of a hydroxycarboxylic acid having the general formula (I): HO−(C)R1R2−(CH2)n−COOX, or having the general formula (II): (HO−(C)R1R2−(CH2)n−COO)2Y, wherein R1 is a hydrogen atom or a methyl group CH3 or an alkyl group having the formula (A): –(CH2)p−CH3 wherein p is an integer between 0 and 6, and R2 is a hydrogen atom or a methyl group CH3 or an alkyl group having the formula (A): –(CH2)p−CH3 wherein p is an integer between 0 and 6, and n is an integer between 0 and 2, and X is an element selected from among sodium, potassium and lithium, and Y is an element selected from among calcium, magnesium, beryllium and zinc. The present invention also relates to a method for manufacturing an insulation product comprising mineral fibers or natural organic fibers which uses the aforementioned aqueous sizing composition, and to an insulation product obtainable by such a method.

Description

[0001] Description

[0002] Title: Water-based sizing composition containing hydrogenated sugar for bonding mineral or natural organic fibers

[0003] The present invention relates to an aqueous sizing composition comprising at least one hydrogenated sugar, at least one polycarboxylic organic acid, and at least one salt of a hydroxylated carboxylic acid as a specific catalyst. This aqueous sizing composition, capable of thermal crosslinking to form an organic binder, allows for the bonding of both mineral and natural organic fibers during the application of insulation products.

[0004] Thus, the invention also relates to a method for manufacturing insulation products comprising mineral fibers or natural organic fibers bonded by an organic binder obtained by hardening or crosslinking said aqueous sizing composition based on hydrogenated sugar. Furthermore, the invention relates to the insulation products obtained by such a method.

[0005] In application WO 2010 / 029266 A1 filed on behalf of the Applicant, a sizing composition for mineral wool was described, comprising at least one hydrogenated sugar, at least one polycarboxylic organic acid, in the presence of a catalyst, such as an alkali salt of a strong acid, preferably sodium hypophosphite. This sizing composition is capable of thermally crosslinking to form an organic binder during the manufacture of insulating products, after application and heating of said sizing composition onto bonded mineral fibers.Indeed, during the crosslinking and / or hardening of the sizing composition, esterification and / or polymerization reactions occur between the carboxyl groups of the polycarboxylic organic acid and the hydroxyl groups of the hydrogenated sugar, forming ester bonds that lead to the formation of a polymer network in the final organic binder (after hardening and / or crosslinking of said sizing composition). This polymer network allows for the establishment of bonds at the fiber junctions during the manufacture of insulating products.

[0006] However, these phosphorus-based catalysts are expensive, unsustainable, toxic to humans, and can harm aquatic life. Furthermore, the aforementioned strong acid alkali salts can also, through a side reaction, react themselves with the polyol (instead of the polycarboxylic acid) in their acidic form (i.e., after exchanging hydrogen atom(s) with the polycarboxylic acid), which halts the elongation of the polymer chain between the hydroxyl groups of the polyol and the carboxyl groups of the polycarboxylic acid. The catalyst is then no longer regenerated.

[0007] The inventors therefore sought bio-based, biodegradable, sustainable, non-toxic, inexpensive catalysts capable of avoiding unwanted reactions, that is, preferably capable of carrying out esterification and polymerization reactions between at least one polycarboxylic organic acid and at least one specific polyol, such as a hydrogenated sugar; such reagents being contained in an aqueous sizing composition. The aim of the invention is consequently to provide aqueous sizing compositions capable of thermal crosslinking, to form organic binders for bonding both natural organic fibers and mineral fibers, in order to obtain insulating products with good mechanical properties, i.e., at least as good as when an alkali salt of a strong acid is used as a catalyst in the aqueous sizing composition.

[0008] In the course of this research, the inventors discovered that a specific alternative catalyst, such as a salt of a hydroxylated carboxylic acid of formula (I) or (II) below, did not present the aforementioned drawbacks and could be used in an aqueous sizing composition comprising at least one hydrogenated sugar and at least one polycarboxylic acid to form insulating products with good mechanical properties. According to the invention, the salt of a hydroxylated carboxylic acid has the general formula (I): HO-(C)R 1 R 2 -(CH2)n-COOX, or of general formula (II): (HO-(C)R 1 R 2 -(CH2)n-COO)2Y, in which

[0009] R 1 is a hydrogen atom, or a methyl group CHs or an alkyl group of formula (A): -(CH2) P -CH3 in which p is an integer between 0 and 6, and

[0010] R 2is a hydrogen atom, or a methyl group CH3 or an alkyl group of formula (A): -(CH2) P -CH3 in which p is an integer between 0 and 6, and n is an integer between 0 and 2, and

[0011] X is an element chosen from among sodium, potassium, and lithium, and

[0012] Y is an element chosen from among calcium, magnesium, beryllium and zinc.

[0013] Thus, the present application relates more specifically to an aqueous sizing composition for bonding mineral or natural organic fibers, characterized in that it comprises the specific combination:

[0014] - at least one hydrogenated sugar,

[0015] - at least one polycarboxylic organic acid,

[0016] - at least one salt of a hydroxylated carboxylic acid: of general formula (I): HO-(C)R 1 R 2 -(CH2)n-COOX, or of general formula (II): (HO-(C)R 1 R2 -(CH2)n-COO)2Y, in which

[0017] R 1 is a hydrogen atom, or a methyl group CHs or an alkyl group of formula (A): -(CH2) P -CH3 in which p is an integer between 0 and 6, and

[0018] R 2 is a hydrogen atom, or a methyl group CH3 or an alkyl group of formula (A): -(CH2) P -CH3 in which p is an integer between 0 and 6, and n is an integer between 0 and 2, and

[0019] X is an element chosen from among sodium, potassium, and lithium, and

[0020] Y is an element chosen from among calcium, magnesium, beryllium and zinc.

[0021] According to the invention, the hydroxylated carboxylic acid of the salt of formula (I) (monovalent salt) or of formula (II) (divalent salt), can be selected from the group consisting of: glycolic acid, lactic acid, mandelic acid, 3-hydroxybutyric acid, 3-hydroxypentanoic acid, 3-hydroxyoctanoic acid, 3-hydroxydecanoic acid, [3-hydroxy [3-methylbutyric acid and 4-hydroxybutanoic acid.

[0022] The amount of salt of a hydroxylated carboxylic acid of formula (I) or (II) introduced into the aqueous sizing composition may represent from 2 to 15% of the weight of the mixture consisting of the hydrogenated sugar and the polycarboxylic organic acid, preferably from 5 to 10%. By "hydrogenated sugar" is meant here all products resulting from the reduction, in any manner whatsoever, of a sugar selected from monosaccharides, oligosaccharides and linear, cyclic or branched polysaccharides, and mixtures of these products, in particular starch hydrolysates.

[0023] The starch hydrolysates according to the invention are obtained in a manner known per se, for example by enzymatic and / or acid hydrolysis. The degree of starch hydrolysis is generally characterized by the dextrose equivalent, also called "Dextrose-Equivalent" (DE) in English, defined by the following relationship:

[0024] / number of broken glycosidic bonds

[0025] DE = 100 x -

[0026] (number of glycosidic bonds in the initial starch)

[0027] The DE of starch hydrolysates varies according to the hydrolysis method used (type of enzyme(s) for example) and the degree of hydrolysis: the distribution into products of different degrees of polymerization can vary to a large extent.

[0028] Preferred starch hydrolysates have a DE between 5 and 99, and advantageously between 10 and 80.

[0029] The hydrogenation of sugar can be carried out by known methods operating under conditions of high hydrogen pressure and temperature, in the presence of a catalyst chosen from groups IB, IIB, 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. Hydrogenation transforms sugar or a mixture of sugars (starch hydrolysate) into the corresponding polyols.

[0030] Although not preferred, hydrogenation can be implemented in the absence of a hydrogenation catalyst, in the presence of a hydrogen source other than hydrogen gas, for example an alkali metal borohydride such as sodium borohydride.

[0031] Examples of hydrogenated sugars include erythritol, arabitol, xylitol, sorbitol, mannitol, iditol, maltitol, isomaltitol, lactitol, cellobitol, palatinitol, maltotrititol and the hydrogenation products of starch hydrolysates, notably marketed by Roquette under the name Polysorb®, or of hydrolysates of lignocellulosic materials, particularly hemicellulose, especially xylans and xyloglucans.

[0032] A hydrogenated sugar chosen from the group formed by maltitol or sorbitol will be used in a particularly preferential manner.

[0033] The hydrogenated sugar according to the invention may contain reducing sugars in a small proportion which does not exceed 5% by weight (of dry matter), preferably 1% and even better 0.5%.

[0034] In the aqueous sizing composition, hydrogenated sugar can represent from 20 to 60% of the weight of the mixture consisting of hydrogenated sugar and polycarboxylic organic acid, preferably from 30 to 50%.

[0035] According to the invention, at least one hydrogenated sugar reacts with at least one polyfunctional crosslinking agent that is a polycarboxylic organic acid. The polycarboxylic organic acid may be a "non-polymeric" or "polymeric" acid.

[0036] According to a first embodiment, the polycarboxylic organic acid is a "non-polymeric" polycarboxylic organic acid. In this application, a "non-polymeric" polycarboxylic organic acid is understood to be a polycarboxylic organic acid that is not a macromolecule consisting of an assembly of monomers having a molar mass between 90 g / mol. 1 and 350 g. mol' 1 linked together by repetitive covalent bonds.

[0037] Preferably, polycarboxylic acids chosen from the group consisting of dicarboxylic acids, tricarboxylic acids and tetracarboxylic acids will be used.

[0038] Dicarboxylic acids are, for example, chosen from the group formed by 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 its derivatives, in particular containing at least one atom of boron or chlorine, tetrahydrophthalic acid and its derivatives, in particular containing at least one atom of chlorine such as chlorendic acid, isophthalic acid, terephthalic acid, mesaconic acid and citraconic acid. 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 include, for example, 1,2,3,4-butanetetracarboxylic acid and pyromellitic acid.

[0039] Even more preferably, the non-polymeric polycarboxylic organic acid is chosen from maleic acid, succinic acid, glutaric acid, itaconic acid and citric acid.

[0040] According to a second embodiment, the polycarboxylic organic acid is a "polymeric" polycarboxylic organic acid. The polymeric organic acids according to the invention can be homopolymers of unsaturated carboxylic acid and copolymers of at least one unsaturated carboxylic acid and at least one vinyl monomer.

[0041] Examples of polymeric polycarboxylic organic acids include homopolymers of unsaturated carboxylic acids such as (meth)acrylic acid, crotonic acid, isocrotonic acid, maleic acid, cinnamic acid, 2-methylmaleic acid, fumaric acid, itaconic acid, 2-methylitaconic acid, and α,p-methyleneglutaric acid; monoesters of unsaturated dicarboxylic acids, such as C1-C10 alkyl maleates and fumarates; and copolymers of at least one of the aforementioned unsaturated carboxylic acids and at least one vinyl monomer such as styrene, substituted or not with alkyl, hydroxyl, or sulfonyl groups, or with a halogen atom, (meth)acrylonitrile, or (meth)acrylamide. by alkyl groups in C1-C10, the alkyl (meth)acrylates, notably methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate and isobutyl (meth)acrylate, glycidyl (meth)acrylate,Butadiene and a vinyl ester, in particular vinyl acetate.

[0042] According to another embodiment, the aqueous sizing composition comprises at least one non-polymeric polycarboxylic organic acid, optionally mixed with at least one polymeric polycarboxylic organic acid.

[0043] In the aqueous sizing composition, the polycarboxylic acid can represent from 40 to 80% by weight of the mixture consisting of the hydrogenated sugar and the polycarboxylic acid, preferably from 50 to 70% by weight. The aqueous sizing composition according to the invention is an aqueous composition that can contain from 60 to 98% by weight of water, preferably between 80 and 98%, and even more preferably between 85 and 95% by weight of water. In other words, the aqueous sizing composition can have a dry matter content of between 2 and 40% by weight, preferably between 2 and 20% by weight, and even more preferably between 5 and 15% by weight. Hydrogenated sugar, polycarboxylic organic acid and the salt of a hydroxylated carboxylic acid of formula (I) or (II) together may represent at least 90%, preferably at least 95%, of the solids of the aqueous sizing composition.

[0044] Preferably, the aqueous sizing composition has a pH between 1 and 6, preferably between 2 and 5, at 10% by weight in aqueous solution.

[0045] The aqueous sizing composition according to the invention may further comprise the following conventional additives in the following proportions calculated on the basis of 100 parts by weight of hydrogenated sugar and polycarboxylic organic acid:

[0046] - 0.2 to 5 parts of silane, in particular an aminosilane or an epoxysilane,

[0047] - 2 to 25 parts oil, preferably 4 to 20 parts,

[0048] - 0.5 to 4 parts of a silicone.

[0049] The role of the additives is known and briefly recalled: silane is a coupling agent between the fibers and the binder, and also plays the role of an anti-aging agent; the oils are dust-repellent and hydrophobic agents and silicone is a hydrophobic agent which has the function of reducing the absorption of water by the insulation product.

[0050] The preparation of the aqueous sizing composition is preferably carried out by simply mixing the aforementioned constituents.

[0051] Furthermore, the aqueous gluing composition according to the invention can be formaldehyde-free. For the purposes of this application, "formaldehyde-free" means an amount of formaldehyde less than 2000 ppm in an aqueous gluing composition according to the invention.

[0052] This application also relates to a method for manufacturing an insulation product comprising mineral fibers or natural organic fibers bonded by an organic binder, using an aqueous sizing composition according to the invention.

[0053] This process comprises the following steps: (a) the application of an aqueous sizing composition as described above to said mineral fibers or said natural organic fibers,

[0054] (b) the formation of an assembly of said mineral fibres or said natural organic fibres bonded together, and

[0055] (c) heating the assembly of said mineral fibers or said natural organic fibers until said sizing composition hardens to form the organic binder.

[0056] In this application, the term "sizing composition" refers to considerably less concentrated aqueous solutions or dispersions having a dry matter content of 40% by weight or less, preferably between 2% and 40% by weight, particularly between 2% and 20% by weight, and even more particularly between 5% and 15% by weight. They have sufficiently low viscosities to allow their application to natural organic or mineral fibers by spraying through nozzles or by impregnation. Furthermore, in this application, "organic binder" means an insoluble binder obtained by hardening (or crosslinking) the aqueous sizing composition previously applied to the fibers during the heating step of the fiber assembly.

[0057] In a preferred embodiment of the process of the invention, step (a) of applying the aqueous sizing composition to the mineral fibers or natural organic fibers can be carried out by spraying, in particular by means of spray nozzles, or by roller coating or by impregnation.

[0058] The aqueous sizing composition is applied to the mineral or natural organic fibers in a quantity of between 2% and 20% by weight, preferably between 3% and 15% by weight, said quantity being expressed in dry matter relative to the weight of the mineral or natural organic fibers, in order to give the insulating product the desired mechanical properties.

[0059] The mineral fibers, according to the invention, are preferably mineral wools and even more preferably glass wool, rock wool, or slag wool, or mixtures thereof. In particular, when the mineral fibers are mineral wools, they may contain a composition corresponding to the following formulation, in percentage by weight: SiO2: between 30 and 50%, preferably between 35 and 45%,

[0060] Na2O: between 0 and 10%, preferably between 0.4 and 7%,

[0061] CaO: between 10 and 35%, preferably between 12 and 25%,

[0062] MgO: between 1 and 15%, preferably between 5 and 13%,

[0063] CaO+MgO: between 11 and 40% cumulatively,

[0064] AI2O3: between 10 and 27%,

[0065] K2O: between 0 and 2%, preferably between 0 and 1%

[0066] Iron oxide: between 0.5 and 15%, preferably between 3 and 12%, other oxide(s): between 0 and 5% cumulatively, preferably less than 3%, the remainder being made up of unavoidable impurities.

[0067] Mineral fibers can be glass fibers or rock fibers, particularly basalt (or wollastonite). More specifically, the mineral fibers according to the invention are aluminosilicate glass fibers, particularly aluminosilicate glass fibers comprising aluminum oxide, Al₂O₃, in a mass fraction of between 10% and 27%. In another embodiment, the mineral fibers can be glass fibers containing a composition conforming to the following formulation, expressed as a percentage by weight:

[0068] SiÛ2: between 50 and 75%, preferably between 60 and 70%,

[0069] Na2O: between 10 and 25%, preferably between 10 and 20%,

[0070] CaO: between 5 and 15%, preferably between 5 and 10%,

[0071] MgO: between 1 and 10%, preferably between 2 and 5%,

[0072] CaO and MgO together preferably represent between 5 and 20%,

[0073] B2O3: between 0 and 10%, preferably between 2 and 8%,

[0074] AI2O3: between 0 and 8%, preferably between 1 and 6%,

[0075] K2O: between 0 and 5%, preferably between 0.5 and 2%,

[0076] Na2O and K2O together preferably represent between 12 and 20%,

[0077] Iron oxide: between 0 and 3%, preferably less than 2%, preferably even less than 1%, other oxide(s): between 0 and 5% cumulative weight, preferably less than 3% cumulative, the remainder being made up of unavoidable impurities.

[0078] The diameter of the mineral fibers is advantageously between 0.1 and

[0079] 25 µm. The diameter of the natural organic fibers is advantageously between 5 and 100 µm, preferably between 10 and 50 µm. The natural organic fibers, according to the invention, are advantageously non-thermoplastic fibers that occur naturally in biomass and may have undergone mechanical and / or chemical treatments. These fibers originate from plant sources and are advantageously selected from cotton and lignocellulosic fibers. "Lignocellulosic fibers" are defined as fibers of plant origin based on lignocellulosic material, that is, comprising cellulose, hemicellulose, and lignin. Lignocellulosic fibers include wood fibers and fibers from other plants, for example, hemp, flax, sisal, cotton, jute, coconut, raffia, abaca, cereal straw, or rice straw.

[0080] The term "lignocellulosic fibres" as used in this application does not include lignocellulosic materials that have been subjected to thermomechanical or chemical treatments for the purpose of manufacturing paper pulp.

[0081] The lignocellosic fibers used in the present invention have therefore simply undergone a mechanical comminution treatment intended to reduce and / or control the size of the fibers.

[0082] The lignocellulosic fibers are preferably softwood fibers, particularly pine, obtained by mechanical defibration. Their diameter is advantageously between 10 and 70 µm, preferably between 30 and 50 µm.

[0083] The application of the aqueous sizing composition a) preferably precedes step (b) of forming an assembly of mineral fibers or natural organic fibers, during which the sizing fibers are gathered together, before being heated consecutively or extemporaneously to harden the sizing composition thus forming the organic binder which binds the fibers.

[0084] Thus, step b) of forming an assembly of mineral or natural organic fibers, which can also be called the fiber assembly shaping step, can be carried out by molding and / or compression. The mold used for molding the products must be made of a material capable of withstanding the temperature of the heating step. It must also have a structure that allows the hot air from the curing oven to easily penetrate the molded product. The mold can, for example, be made of a wire mesh box. The wire mesh box is preferably filled with a volume of loose fibers exceeding its capacity and is then closed with a wire mesh lid. The fibers are thus compressed to a greater or lesser degree depending on the excess volume of the filling.This excess volume of filling of the box by the fibers is for example between 10% and 150%, preferably between 15% and 100% and in particular between 20% and 80%.

[0085] When the process of the present invention is a continuous process, step b) of forming a fiber assembly can be done for example by compression using a roller located at the entrance of the baking oven on a conveyor.

[0086] Furthermore, the fibers can be assembled:

[0087] - in flexible fiber mattresses that can be rolled up, compressed or folded,

[0088] - in sheets or panels of fibers, denser and more rigid than roll-up mattresses,

[0089] - in molded fiber-based products, for example duct or pipe linings,

[0090] - in woven or non-woven textiles, such as non-woven mats of glass or organic fibers.

[0091] In a particular embodiment of the process according to the invention, the fibers are natural organic fibers impregnated with an aqueous sizing composition, and the process further comprises, between steps a) and b), a fiber drying step intended to evaporate sufficient water to render the sizing or unsizing fibers substantially non-sticky. In another embodiment, the drying step may be carried out before step a). This drying step may be performed by heating, for example, in a thermostatically controlled ventilated oven or using a steam press. It is important to ensure that the drying process does not raise the temperature of the natural organic fibers too high, which would result in the softening of the dried sizing composition or even the beginning of cross-linking of the components of the sizing composition.A heating temperature close to the boiling point of water is generally sufficient. Drying of fibers impregnated with aqueous sizing is therefore preferably carried out by heating at a temperature between 70°C and 150°C for a duration of between 1 and 10 seconds. The natural organic fibers obtained after the drying step are encased in a sheath of dried sizing.

[0092] Step (c) of heating the fiber assembly according to the process of the invention is preferably carried out, when dealing with natural organic fibers, at a temperature between 90°C and 170°C, preferably between 100°C and 160°C, for a duration of between 1 and 30 minutes, and when dealing with mineral fibers, at a temperature between 170°C and 250°C, preferably between 180°C and 210°C, for a duration of between 1 and 10 minutes, advantageously in a temperature-controlled chamber or a steam press. In the case of a temperature-controlled chamber, this may be a forced-air oven in which hot gases of controlled temperature are introduced into one or more compartments, or a fluid-circulating or heating element mold.During this heating stage of the assembly of said mineral fibers or said natural organic fibers, the constituents of the sizing composition (according to the invention) harden / or crosslink / polymerize to form an insoluble organic binder.

[0093] In another particular embodiment of the process according to the invention, the fibers are mineral fibers and after step (c) of heating the assembly of said mineral fibers until hardening of the sizing composition, the assembly of mineral fibers exhibits a loss on ignition (LOI) of between 1% and 20%, preferably between 1% and 15% by weight.

[0094] The invention also relates to an insulating product obtainable by the process described above. This insulating product comprises mineral fibers or natural organic fibers bonded with a binder obtained by hardening or crosslinking an aqueous sizing composition (as described above) comprising a hydrogenated sugar, a polycarboxylic organic acid, and a salt of a hydroxylated carboxylic acid of formula (I) or formula (II). The resulting insulating product exhibits improved mechanical properties compared to an insulating product obtained using an aqueous sizing composition without a catalyst. Furthermore, the resulting insulating product exhibits equivalent, or even improved, mechanical properties compared to those of an insulating product obtained using an aqueous sizing composition employing an alkali salt of a strong acid as a catalyst.The insulating product can have a thickness of between 10 and 400 mm, preferably between 35 and 240 mm, measured according to standard EN 823:2013 and a density of between 5 and 200 kg / m³. 3 , preferably between 8 and 180 kg / m 3 The resulting insulating product can be used to make panels for exterior and interior building insulation. This insulating product is generally in the form of a batt or felt of mineral wool, glass wool, or rock wool, or a veil of mineral fibers, also glass wool or rock wool, intended primarily to form a surface covering for said batt or felt. These products have a particularly advantageous white color.

[0095] The resulting insulating product can therefore be a thermal and / or acoustic insulating product.

[0096] Examples

[0097] Wood fibers

[0098] We prepare aqueous sizing compositions comprising the constituents listed in Table 1.

[0099] The hydrogenated sugar used is maltitol (Maltilite ® 5575) which represents 48% of the weight of the mixture consisting of maltitol and the polycarboxylic organic acid used which is citric acid.

[0100] Aqueous sizing compositions are prepared by successively introducing into a container hydrogenated sugar (maltitol), polycarboxylic organic acid (citric acid) and catalyst such as sodium hypophosphite (denoted "HPS") (comparative example: 1), sodium lactate (denoted "NaL") (example according to the invention: 2) or sodium glycolate (example according to the invention: 3), under vigorous stirring until complete dissolution of the constituents.

[0101] The amount of catalyst added in each of the aqueous sizing compositions (1 to 3) represents 5% of the weight of the mixture consisting of hydrogenated sugar and polycarboxylic organic acid.

[0102] All aqueous sizing compositions 1 to 3 contain 91% water by weight and 9% dry matter by weight and have a pH of approximately 2.3. [Table 1]

[0103] Sizing compositions 1 to 3, as previously described, are deposited onto wood fibers to produce wood fiberboard test pieces. For each test, wood fibers are impregnated with an aqueous sizing composition. The amount of aqueous composition deposited on the wood fibers is equal to 7% by weight, expressed as dry matter relative to the weight of the wood fibers.

[0104] The impregnated wood fibers are then deposited uniformly in a steel mold with an open cavity measuring 60 mm x 10 mm x 12 mm. Steel bars measuring 60 mm x 10 mm x 10 mm are placed on top of the wood fibers, and the assembly is heated for 30 minutes in a thermostatically controlled press at 150°C and under a pressure of 10 bar. The mold is then allowed to cool to room temperature before removing the resulting lignocellulosic fiber specimen (60 mm x 10 mm x 2 mm).

[0105] The wood fibre test specimens thus obtained have a density of approximately 180 kg / m³ 3 .

[0106] The flexural strength modulus (three-point bending) is then determined for each specimen by dynamic thermomechanical analysis (DMTA) using a TA Instruments RSA-G2 Analyzer. The samples are first dried for several hours in a dynamic vacuum dryer (20 mbar).

[0107] The operating parameters of the measuring device are as follows: Temperature: 25 °C

[0108] Poisson ratio: 0.45

[0109] Duration of the oscillatory mechanical stress: 120 seconds

[0110] Oscillation frequency: 1.0 Hz,

[0111] Deformation: 0.1%

[0112] Sampling rate: 10 points / second.

[0113] Table 2 below shows the storage modulus of the wood fiber specimens obtained after hardening of each of the sizing compositions. Each storage modulus value is the average calculated from two to four individual measurements.

[0114] [Table 2]

[0115] It is observed that the wood fiber test specimens prepared according to the invention, i.e., using sizing composition 2 or sizing composition 3 comprising a combination of maltitol (hydrogenated sugar), citric acid (polycarboxylic organic acid) in the presence of a specific catalyst such as sodium lactate or sodium glycolate, both of which are salts of hydroxylated carboxylic acids, have a conservation modulus of the same order of magnitude (57 MPa / 55 MPa) as that obtained for wood fiber test specimens prepared using sizing composition 1 (comparative example) in which the catalyst used is HPS (an alkali salt of a strong acid with 56 MPa). Glass fibers

[0116] Water-based sizing compositions are prepared comprising the constituents listed in Table 3 below.

[0117] The hydrogenated sugar used is:

[0118] - either maltitol (Maltilite ® 5575) for sizing compositions 4 and 5, and in this case maltitol represents 48% of the weight of the mixture made up of maltitol and citric acid,

[0119] - either sorbitol for sizing compositions 6 to 9, and in this case sorbitol represents 30% of the weight of the mixture made up of sorbitol and citric acid (compositions 6 and 7) or 34% of the weight of the mixture made up of sorbitol and succinic acid (compositions 8 and 9).

[0120] Aqueous sizing compositions are prepared by successively introducing into a container hydrogenated sugar (maltitol or sorbitol), polycarboxylic organic acid (citric acid or succinic acid) and catalyst such as sodium hypophosphite (comparative examples: 4, 6 and 8), sodium lactate (examples according to the invention: 5, 7 and 9), under vigorous stirring until complete dissolution of the constituents.

[0121] The amount of catalyst added in each of the sizing compositions (4 to 9) represents 5% of the weight of the mixture consisting of hydrogenated sugar and polycarboxylic organic acid.

[0122] All aqueous sizing compositions 4 to 9 contain 91% by weight of water and 9% by weight of dry matter and have a pH between 2 and 2.5.

[0123] Compositions 4 to 9, as previously described, are then used to form fiberglass-based insulating products.

[0124] To achieve this, two overlapping pieces (60 mm x 10 mm x 0.250 mm) of non-woven glass fiber paper are impregnated with each of the aqueous sizing compositions, and then the impregnated glass fiber papers are cured at a temperature of 210°C for 4 minutes. The quantity of aqueous compositions deposited on the glass fibers is equal to 10% by weight, expressed as dry matter relative to the weight of the glass fibers.

[0125] The sample preservation module is measured in three-point bending during cooking by dynamic thermomechanical analysis (DMTA) using a TA Instruments RSA-G2 Analyzer. The operating parameters of the measuring device are the same as those mentioned above.

[0126] Table 3 below also shows the preservation modulus of the fiberglass papers obtained after curing each of the sizing compositions. Each preservation modulus value is the average calculated from two to four individual measurements.

[0127] [Table 3]

[0128] It has been observed that the use of a specific catalyst such as sodium lactate, which is a salt of a particular hydroxylated carboxylic acid, in an aqueous sizing composition comprising a hydrogenated sugar such as maltitol or sorbitol, in the presence of a polycarboxylic organic acid such as citric acid or succinic acid, according to the invention (samples 5, 7, and 9 with 287 MPa / 106 MPa / 27 MPa), makes it possible to obtain glass fiber papers with a better preservation modulus than when the strong acid catalyst, HPS, is used (comparative samples 4, 6, and 8 with 281 MPa / 84 MPa / 19 MPa). Examples produced on an industrial line

[0129] The compositions of examples 4 and 5 are used to form glass wool-based insulation products on an industrial line; as well as composition 10, which is obtained by mixing maltitol (Maltilite ® 5575), which represents 48% of the weight of the mixture consisting of maltitol and the polycarboxylic organic acid used, which is citric acid, in the presence of 5% by weight of calcium lactate (catalyst according to the invention, noted "CaL") relative to the mixture consisting of hydrogenated sugar and the polycarboxylic organic acid.

[0130] Glass wool is manufactured by the internal centrifugation technique in which the molten glass composition is transformed into fibers by means of a tool called a centrifugal plate, comprising a basket forming a receiving chamber for the molten composition and a peripheral band pierced with a multitude of orifices: the plate is moved in rotation around its vertically arranged axis of symmetry, the composition is ejected through the orifices under the effect of centrifugal force and the material escaping from the orifices is drawn into fibers with the assistance of a drawing gas stream.

[0131] Typically, a spray ring of adhesive is placed below the fiber-laying plate to evenly distribute the adhesive composition over the newly formed glass wool.

[0132] The bonded mineral wool is collected on a conveyor belt equipped with internal suction chambers that retain the mineral wool in the form of a felt or sheet on the conveyor surface. The conveyor then passes through an oven maintained at 250°C where the bonding agents polymerize to form a binder. The resulting insulating product has a density of 17.5 kg / m³. 3 , a thickness of approximately 82 mm immediately after manufacture and a loss on ignition of around 5%.

[0133] In these examples, the "tensile strength," according to ASTM C 686-71 T, is measured on a sample stamped from the insulating product. The sample is in the shape of a torus 122 mm long, 46 mm wide, with a cutting radius of 38 mm on the outer edge and a cutting radius of 12.5 mm on the inner edge.

[0134] The sample is placed between two cylindrical mandrels of a testing machine, one of which is mobile and moves at a constant speed. The sample's breaking force L is measured, and the tensile strength RT is calculated, defined as the ratio of the breaking force L (in Newtons) to the sample's mass (in Newtons per gram). The tensile strength is measured immediately after manufacturing (tensile strength before aging) or after autoclave aging (after accelerated aging in an autoclave at a temperature of 105°C and 100% relative humidity for 15 minutes).

[0135] The "thickness recovery" indicates the compressive elasticity of the final product. To measure it, a compressive pressure is applied for a given time, reducing the thickness to 1 / 4.8 of its initial value. After releasing this compressive pressure, the thickness is measured again. The thickness recovery is the ratio of the thickness measured after the compression pressure is released to the initial thickness.

[0136] Water absorption is measured under the conditions of standard EN 1609, and expressed in kg of water absorbed per m² 2 of insulating product. Insulation products with a water absorption rate of less than 1 kg / m³ 2 are considered to have low short-term (24 hours) water absorption: they belong to the "WS" class according to the ACERMI certification.

[0137] The properties of the insulation products are given in Table 4 below.

[0138] [Table 4]

[0139]

[0140] Insulation products manufactured with aqueous adhesive compositions 5 and 10 (according to the invention) exhibit properties similar to the reference product 4 (comparative example), whether in terms of:

[0141] - tensile strength, before and after aging, and

[0142] - of thickness recovery after compression for 1 hour, 1 month, 3 months and 6 months.

[0143] In conclusion, Tables 2, 3 and 4 show that the use of a salt of a particular hydroxylated carboxylic acid (as a catalyst) in combination with a hydrogenated sugar and a polycarboxylic organic acid makes it possible to bind both mineral and natural organic fibers and to obtain insulating products with mechanical properties as good as, or even better than, those obtained using known sizing compositions using an alkali salt of a strong acid as a catalyst.

Claims

Demands 1. Aqueous sizing composition for bonding mineral or natural organic fibers, characterized in that it comprises: - at least one hydrogenated sugar, - at least one polycarboxylic organic acid, - at least one salt of a hydroxylated carboxylic acid: of general formula (I): HO-(C)R 1 R 2 -(CH2)n-COOX, or of general formula (II) (HO-(C)R 1 R 2 -(CH2)n-COO)2Y, in which R 1 represents a hydrogen atom, a methyl group CH3 or an alkyl group of formula (A): -(CH2) P -CH3 in which p is an integer between 0 and 6, and R 2 represents a hydrogen atom, a methyl group CH3 or an alkyl group of formula (A): -(CH2) P -CH3 in which p is an integer between 0 and 6, and n is an integer between 0 and 3, and X is an element chosen from among sodium, potassium, and lithium, and Y is an element chosen from among calcium, magnesium, beryllium and zinc.

2. Aqueous sizing composition according to claim 1, characterized in that the hydrogenated sugar is a product resulting from the reduction of a sugar selected from monosaccharides, oligosaccharides and linear, cyclic or branched polysaccharides, and mixtures of these products.

3. Aqueous sizing composition according to claim 1 or 2, characterized in that the hydrogenated sugar is selected from the group consisting of erythritol, arabitol, xylitol, sorbitol, mannitol, iditol, maltitol, isomaltitol, lactitol, cellobitol, palatinitol, maltotrititol and hydrogenation products of starch hydrolysates or lignocellulosic materials.

4. Aqueous sizing composition according to any one of the preceding claims, characterized in that the polycarboxylic organic acid is a non-polymeric polycarboxylic acid.

5. A water-based sizing composition according to any one of the preceding claims, characterized in that the non-polymeric polycarboxylic organic 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, in particular containing at least one boron or chlorine atom, tetrahydrophthalic acid, in particular containing at least one chlorine atom, isophthalic acid, terephthalic acid, mesaconic acid, and citraconic acid, tricarboxylic acids, including citric acid, tricarballylic acid, 1,2,4-butanetricarboxylic acid, aconitic acid,hemimellitic acid, trimellitic acid and trimesic acid, and tetracarboxylic acids, including 1,2,3,4-butanetetracarboxylic acid and pyromellitic acid.

6. Aqueous gluing composition according to any one of claims 1 to 3, characterized in that the polycarboxylic organic acid is a polymeric polycarboxylic acid, in particular selected from homopolymers of unsaturated carboxylic acid and copolymers of at least one unsaturated carboxylic acid and at least one vinyl monomer.

7. Aqueous sizing composition according to any one of the preceding claims, characterized in that the hydroxylated carboxylic acid of the salt of formula (I) or (II) is selected from the group consisting of: glycolic acid, lactic acid, mandelic acid, 3-hydroxybutyric acid, 3-hydroxypentanoic acid, 3-hydroxyoctanoic acid, 3-hydroxydecanoic acid, [3-hydroxy [3-methylbutyric acid and 4-hydroxybutanoic acid.

8. Water-based sizing composition according to any one of the preceding claims, characterized in that it contains from 60 to 98% by weight of water.

9. Aqueous sizing composition according to any one of the preceding claims, characterized in that the hydrogenated sugar represents from 20 to 60% of the weight of the mixture consisting of the hydrogenated sugar and the polycarboxylic organic acid, preferably from 30 to 50%.

10. Aqueous sizing composition according to any one of the preceding claims, characterized in that the salt of a hydroxylated carboxylic acid of formula (I) or (II) represents from 2 to 15% of the weight of the mixture consisting of the hydrogenated sugar and the polycarboxylic organic acid, preferably from 5 to 10%.

11. A process for manufacturing an insulation product comprising mineral fibers or natural organic fibers bonded by an organic binder, said process comprising the following steps: (a) the application of an aqueous sizing composition according to any one of claims 1 to 10 on said mineral fibers or said natural organic fibers, (b) the formation of an assembly of said mineral fibres or said natural organic fibres bonded together, and (c) heating the assembly of said mineral fibers or said natural organic fibers until said sizing composition hardens to form the organic binder.

12. A method according to claim 11, wherein the mineral fibers are glass fibers or rock fibers or slag fibers, or mixtures thereof.

13. A method according to claim 11, wherein the natural organic fibers are selected from wood fibers, hemp, flax, sisal, cotton, jute, coconut, raffia, abaca, or even cereal straw or rice straw.

14. A method according to any one of claims 11 to 13, characterized in that step (c) comprises heating said fiber assembly natural organics at a temperature between 90°C and 170°C, for a period of between 1 minute and 30 minutes or heating said mineral fiber assembly at a temperature between 170°C and 250°C, for a period of between 1 and 10 minutes, preferably in a temperature-controlled chamber or steam press.

15. Insulation product obtainable by a process according to any one of claims 11 to 14.

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