Improved lignin-based binder compositions and uses thereof

Abstract

The present invention relates to an aqueous curable binder composition comprising (i) from more than 50 - 90 wt% of a polyphenolic macromolecular compound, a polyprimary amine and a carbohydrate selected from monosaccharide, disaccharide, trisaccharides, tetrasacharides, pentasaccharides and / or reaction products thereof. The invention binder is suitable to bond fibers, such as mineral fibers, synthetic fibers, wood fibers, wood particles, wood chips, wood strands or wood sheets to form insulation products and wood boards. The binder shows good bond strength notably under wet conditions.

Description

[0001] Improved Lignin-based Binder Compositions and Uses Thereof

[0002] The present invention relates to binder compositions, more specifically curable binder compositions for use in manufacturing products from a collection of non or loosely assembled matter. For example, these binder compositions may be employed to fabricate fiber products which may be made from woven or nonwoven fibers. In one illustrative embodiment, the binder compositions are used to bind glass fibers to make fiberglass. In another illustrative embodiment, the binder compositions are used to bind mineral wool fibers, such as glass wool or stone wool in a matted layer, such as an insulating product. In a further embodiment, the binders are used to make cellulosic compositions or product. With respect to cellulosic compositions, the binders may be used to bind cellulosic matter to fabricate, for example, wood fiber board or particle board which has desirable physical properties (e.g., mechanical strength). The invention further extends to a product made from loosely assembled matter bound by a binder of the invention.

[0003] Known thermosetting binders comprise a variety of phenol-aldehyde, urea-aldehyde, melamine-aldehyde, and other condensation-polymerization materials such as furane and polyurethane resins. Aldehyde based binders and more particularly formaldehyde based or generating binders are widely used.

[0004] Alternative formaldehyde-free binder compositions include polyester-based binders obtained by the reaction of a polycarboxylic acid polymer and a polyol that form a thermoset when heat cured. More recently, formaldehyde free binders have been made from sustainable materials, such as from the condensation of amine groups containing compounds with reducing sugars as thermosets. These alternative chemistries show advantages as compared to prior formaldehyde based technology, but also show certain weaknesses, and there is still a need for alternative binder chemistry. Some of these known binder chemistries show a relatively high loss of water in the condensation reaction, which may have a negative impact on the internal bond strength and / or swelling properties of products.

[0005] A. Faure et al disclose in their review article "Catechols as versatile platforms in polymer chemistry" published in Progress in Polymer Science 38 (2013), 236-270, that catechol units containing compounds show strong adhesion to a large range of surfaces, even under wet conditions. The authors review methods to incorporate catechol units in complex functionalized macromolecules.

[0006] Lignin is a constituent of woody plants, composed of a complex group of phenolic polymers that provide strength and rigidity to woody cell walls of various plants. The lignin molecule is complex and not yet fully understood. Lignosulfonates are derived from lignin by sulfonation, for instance in a wood pulping process, more specifically with salts of bisulfite / sulfite. The sulfonate complex may be in association with calcium, magnesium, ammonium, or sodium. Lignin or lignosulfonate lignin may also be found in association with carboxylic acid, or be treated, e.g. by way of oxidation. The material composition may obviously vary since it is produced from naturally occurring sources. Lignin and its derivatives have several advantages, such as renewability, biodegradability, low cost and available supply. Lignosulfonates are used in the concrete industry as dispersing agents and to delay the setting of concrete. They may be used as additives in oil well drilling, dispersants for dyestuffs, cleaning agents, and as a partial substitute for phenol in the manufacture of adhesives. Sodium lignosulfonate is potentially useful in inhibiting corrosion and scale formation in recirculating cooling water systems. In some applications, lignosulfonate salts are reacted with certain amines to form dyes (see for instance US-5989299) or dispersants. US-4130515 discloses a lignin-based resin binder produced by copolymerization of a lignosulfonate salt with melamine and formaldehyde.

[0007] WO2022 / 144107 relates to insulation products made with a binder composition comprising carboxylic acid containing-lignosulfonate lignin, crosslinker and possibly plasticizer. The crosslinker may be hexamethylene diamine, and the plasticizer may be a polysaccharide.

[0008] WO2023 / 111465 discloses a process for the manufacturing of insulation products comprising mineral fibers or natural organic fibers, the fiber substrate being bonded by a binder obtained from a binder composition comprising lignin, possibly oxidized lignin, and at least one organic non-polymeric polycarboxylic acid. The term "lignin" is understood to include Kraft lignin, lignosulfonates, organosolv lignins and bio-refined lignins from lignocellulosic material. The polyfunctional monomeric acid is believed to crosslink the lignin molecules to form a curable resin binder.

[0009] WO2021 / 197662 also discloses binder compositions for mineral fibers comprising Kraft lignins, a multifunctional organic amine, such as HMDA, and a plasticizer such as polysaccharide.

[0010] W02016 / 009054 discloses aqueous curable binder compositions comprising a polyphenolic macromolecular compound and a polyamine functional compound and / or a reaction product thereof, possibly together with a matrix polymer, such as polymers of natural and / or synthetic origin. Naturally derived polymers may be selected from cellulose and its derivatives. Some binder compositions may comprise other polysaccharides such as alginates, starch, chitin and chitosan, agarose, hyaluronic acid, and their derivatives or copolymers (e.g., graft-copolymer, block copolymer, random copolymers), or mixtures thereof.

[0011] US2012 / 135152 relates to binder compositions with extended shelf life, comprising reducing sugar, primary amine and optionally an extender which may inter alia be lignosulfonate. The maximum proportion of extender is 25 wt.% based on binder solids. Examples 16 - 24 show binder compositions comprising reducing sugar, HMDA and sodium lignosulfonate (ARBO SOI).

[0012] US2023 / 192935 discloses the preparation of pre-condensates based on lignosulfonate, glyoxal and urea, and combines these with amine and dextrose.

[0013] The present invention now seeks to provide binders which generate or promote cohesion and are capable of holding a collection of matter together such that the matter adheres in a manner to resist separation. An objective of the present invention is to provide binders showing high bond strength, and more specifically high wet bond strength as compared to known binder compositions.

[0014] Another objective of the present invention is to provide cost-effective binder compositions for large volume applications.

[0015] Another objective is to provide a binder composition based on renewable and / or sustainable resources.

[0016] Further, the invention seeks to provide binder compositions that rapidly cure into strong binders.

[0017] Yet another purpose of the invention is to provide an assembly of matter bonded with the invention binder.

[0018] The present invention now provides an aqueous curable binder composition comprising a polyphenolic macromolecular compound in a concentration of more than 50 - 90 wt.%, a polyamine functional compound and a carbohydrate selected from monosaccharide, disaccharide, trisaccharides, tetrasacharides, pentasaccharides and / or reaction products thereof, in accordance with the claims. The term polyphenolic macromolecular compound as used herein designates a macromolecular compound, preferably an essentially natural macromolecular compound or a macromolecular compound derived from a natural macromolecular compound, which bears a multitude of phenol or polyhydroxybenzene radicals, such as catechol radicals (dihydroxybenzene). Examples of such polyphenolic macromolecular compounds are lignins, lignosulfonate salts and condensed tannins and mixtures thereof.

[0019] Lignins may be in the form of Kraft lignin or other forms, depending on the way they are isolated. The term further includes modified or treated lignins, such as oxidized lignins which have been oxidized with hydrogen peroxide for instance, or acidified lignins which contain desired amounts of acid. Lignosulfonate salts may advantageously be selected from calcium lignosulfonate, sodium lignosulfonate, potassium lignosulfonate, ammonium lignosulfonate, magnesium lignosulfonate and mixtures thereof.

[0020] Tannins are commonly found in plants. Compounds of interest in accordance with the invention comprise polyphenolic macromolecular compounds, hence may be essentially condensed tannins.

[0021] According to a preferred embodiment of the present invention, the polyamine functional compound is a polyprimary amine comprising two or more primary amine functional groups and may be selected from diamines, triamines, tetramines, pentamines and polymeric polyamines. Preferred polyprimary amines are those in which the spacer group between two primary amines is a straight or branched alkenyl group with 2 to 25 C-atoms, preferably 4 to 25 C-atoms, or a mono- aromatic group, wherein the primary amine functional groups are bound to the aromatic group either directly or through an intermediate spacer alkylene, or a polyaromatic group, wherein the primary amine functional groups are bound to the polyaromatic group either directly or through an intermediate spacer alkylene at distant opposite positions. Examples are hexamethylenediamine, triprimary triamines, ethylene diamine, 1,3-diaminopropane, cadaverine, putrescine, 1,7-diaminoheptane, 1,8- diaminooctane, 2,2,4-trimethylhexamethylenediamine, diaminotoluene, benzidine, or mixtures thereof.

[0022] The monosaccharide may be a monosaccharide in its aldose or ketose form, including a triose, a tetrose, a pentose, a hexose or a heptose, or combinations thereof. It may be a reducing sugar or one that forms a reducing sugar in situ under thermal curing conditions. When a triose is used, an aldotriose or ketotriose sugar may be used, such as glyceraldehyde or dihydroxyacetone. When a tetrose is used, aldotetrose sugars, such as erythrose and threose, or ketotetrose sugars, such as erythrulose, may be used. When pentose sugars are used, ribose, ribulose, arabinose, arabulose, xylose, xylulose, lyxose, or lyxulose, may be used. When a hexose sugar is used, dextrose, mannose, galactose, allose, altrose, talose, gulose, iodose, fructose, psicose, sorbose, or tagatose may be used. When a heptose is used, sedoheptulose may be used. The saccharide is advantageously selected from dextrose, fructose, xylose and combinations thereof.

[0023] Disaccharides may advantageously be selected from sucrose, lactose, maltose and cellobiose.

[0024] The trisaccharide may be raffinose.

[0025] The tetrasaccharide may be stachyose.

[0026] The pentasaccharide may be verbascose. The concentration of polyphenolic macromolecular compound in the composition may vary from 55 to 85 wt.%, preferably from 55 to 80 wt.% or more preferably from 60 to 75 wt.%.

[0027] The polyamine functional compound may range from 2.5 to 40 wt.%, preferably from 5 to 35 wt.% or from 10 to 30 wt.% or even 25 Wt.%.

[0028] Preferably, the ratio of reactive groups on the macromolecules to reactive amino groups in the amine components may be in the range of 10:1 to 1:1.

[0029] The concentration of carbohydrate may vary from 5 to 45 wt.%, preferably from more than 5 or from 6 to 40 wt.%, more preferably from 7 to 35 wt.%, more particularly from 10 to 30 wt.% or 10 to 25 wt.%.

[0030] Preferred binder compositions comprise a lignosulfonate salt, preferably ammonium lignosulfonate or calcium or magnesium or potassium lignosulfonate, and a diamine, such as hexamethylenediamine (HMDA).

[0031] It has been shown that such binder compositions produce cured binders showing high bond strength and performance, particularly under wet conditions, with fast curing rate under usual curing conditions, notably temperatures ranging from 60 - 280 °C, advantageously higher than 80 °C, preferably higher than 100 °C, and advantageously lower than 250 °C, preferably lower than 200 °C, preferably 120 - 180 °C. The duration of applying energy for curing purposes is not particularly restricted and may vary from 1 to 240 minutes, preferably less than 200 min, more preferably less than 120 min or even 60 min. Curing durations of up to 40 min, 30 min or 20 min are possible. It has further been found that invention compositions show particularly surprising bond strength after tropical ageing conditions over extended periods of time.

[0032] Catalysts or surface-active agents are not required but may be added in some particular applications. Preferably the pH is maintained at or above 8, preferably at about pH = 8.5. Such preferred binder compositions cure with only few or substantially no water formation, which makes them a binder of choice in the production of mineral wool-based insulation products and cellulose based boards, such as wood fiber boards or wood particle boards. The energy required for the manufacturing of such products is particularly reduced as curing occurs at low temperature and further as substantially no additional energy is required for water evaporation or drying of the product. The reduced water generation during curing positively affects at least the swelling properties of the product made with the relevant binder composition.

[0033] The invention binder composition is preferably a no-added formaldehyde binder, that is that none of the ingredients of the binder composition comprise formaldehyde. The binder compositions of the invention and binders produced therefrom are essentially formaldehyde-free (that is that they liberate less than about 5 ppm formaldehyde based on the weight of the composition as a result of drying and / or curing) or formaldehyde-free (that is liberating less than about 1 ppm formaldehyde based on the weight of the composition as a result of drying and / or curing). They are preferably formaldehyde-free. Furthermore, they are preferably based on natural, hence renewable, resources.

[0034] The compositions may further comprise dyes, antifungal agents, antibacterial agents, dedusting oil, hydrophobic agents, thickeners and other additives known in the relevant art, or mixtures thereof, for example in amounts ranging from 0.1 to 15 % by weight of binder solids. Sil iconcontaining coupling agents may be present in such binder, generally in the range from about 0.1 to about 5 % by weight based on the weight of the solids in the binder composition. Dedusting oil may be present at up to 10 wt.%.

[0035] Without being bound by theory, it is believed that curing generates highly crosslinked high molecular weight polymers. These may be analysed by a sol-gel method, rheology and other known techniques.

[0036] The preferred binders generated by curing the aqueous binder compositions of the invention are environmentally friendly as they are based on natural products and essentially free of formaldehyde. In addition, in some embodiments, curing may be effected under reduced temperatures as compared to known binder compositions, which also favourably adds to the environmental related aspects of the binders.

[0037] According to the present invention, the term "binder composition" includes any composition comprising a polyphenolic macromolecular compound, a polyamine functional compound and selected carbohydrates as per the invention, which is capable of binding loosely assembled matter, either as such or upon curing.

[0038] As used herein, the term "binder composition" means all ingredients applied to the substrate or present on the substrate prior to curing, other than the substrate itself and any moisture contained in the substrate, including reactants, solvents (including water) and additives. The term "dry weight of the binder composition" as used herein means the weight of all components of the binder composition other than any water that is present (whether in the form of liquid water or in the form of water of crystallization).

[0039] As used herein, the term "aqueous" means a solution and / or dispersion which comprises water as a solvent. Said term further includes compositions or mixtures which contain water and one or more additional solvents. An "aqueous binder composition" of the invention may be a solution or partial solution of one or more of said binder components or may be a dispersion, such as an emulsion or suspension.

[0040] The solid content of the aqueous binder composition may range from 2 to 95 w%, advantageously from 8 to 90 w%, preferably from 10 to 85 w%, based on the weight of the total aqueous binder composition. More specifically, when used as a binder for mineral wool insulation, the solid content of the aqueous binder composition may be in the range from 2 to 25 w%, preferably from 8 to 20 w%, more preferably from 10 to 20 w% or even 12 to 18 w%, based on the weight of the total aqueous binder composition. When used as a binder in wood boards, the solid content of the aqueous binder composition may range from 50 to 95 w%, preferably 50 to 90 w%, more preferably 55 to 85 w% or even 60 to 80 w%, based upon the weight of the total aqueous binder composition.

[0041] The components of the binder composition may be transported separately and combined shortly before use in the relevant manufacturing plant. It is also possible to transport the binder composition as such.

[0042] The binders of the invention may be used to bond a collection of non or loosely assembled matter. The collection of matter includes any collection of matter which comprises fibers selected from mineral fibers, slag wool fibers, stone wool fibers, glass fibers, aramid fibers, ceramic fibers, metal fibers, carbon fibers, polyimide fibers, polyester fibers, rayon fibers, and cellulosic fibers. Further examples of collection of matter include particulates such as coal, sand, cellulosic fibers, wood shavings, saw dust, wood pulp, ground wood, wood chips, wood strands, wood sheets or layers, other natural fibers, such as jute, flax, hemp, straw, wood veneers, facings and other particles, woven or non-woven materials. According to a specific embodiment of the invention, the collection of matter is selected from wood particles and mineral fibers.

[0043] In one illustrative embodiment, the binder composition of the invention may be used to make thermal insulation products, comprising mineral fibers. In such an application, the fibers are bonded together such that they become organized in a fiberglass mat which may then be processed into an insulation product. In such an application, the fibers are generally present in an amount ranging from 70 to 99% by total weight of the insulation product, notably from 80 to 99% or from 85 to 99%.

[0044] According to another embodiment of the invention, the binder may be used to bond cellulosic particles, such as cellulosic fibers, wood shavings, wood pulp and other materials commonly used to manufacture composite wood boards, including fiber boards, particle boards, oriented strand boards, plywood etc. Such wood boards show nominal thicknesses ranging from 6 to 30 mm and a modulus of Elasticity of at least about 1000 N / mm2, bending strength of at least about 5 N / mm2 and / or an internal bond strength of at least 0.10 N / mm2. In such applications, the binder content in the final wood board may range from about 5 to 30 % wt with respect to the total weight of the wood board notably from 9 to 20%. The main components of the aqueous uncured binder composition, that is the polyphenolic macromolecular compound and the polyamine functional compound may be at least partially soluble in water.

[0045] The aqueous binder composition may be applied onto the fiber or particular material by spray application. Other possible techniques include roll application or mixing and / or tumbling the collection of matter with the binder composition. As water evaporates the binder composition may form a gel that bonds the particulate material together when arranged into a desirable assembly. When curing, the polyphenolic macromolecular compound and the polyamine functional compound are caused to react to form an essentially water insoluble macromolecular binder. Curing thus imparts increased adhesion, durability and water resistance as compared to uncured binder. Curing may be effected at temperatures between ambient and up to 280 °C.

[0046] According to another aspect, the invention covers a process for the preparation of an assembly of fibrous or particulate materials or chips, strands or sheets according to the claims. In the process a combination of (i) more than 50 - 90 wt.% of a polyphenolic macromolecular compound which bears a multitude of phenol or polyhydroxybenzene radicals, such as catechol radicals (dihydroxybenzene), preferably lignins, lignosulfonate salts and condensed tannins and mixtures thereof, and (ii) a polyamine functional compound which advantageously is a polyprimary amine comprising two or more primary amine functional groups and may be selected from diamines, triamines, tetramines, pentamines and polymeric polyamines, and (iii) a carbohydrate selected from monosaccharide, disaccharide, trisaccharides, such as raffinose, tetrasacharides, such as stachyose, pentasaccharides, such as verbascose, and / or reaction products thereof, may be applied in aqueous form onto a collection of fibers or particles, chips, strands or sheets, the coated fibers, particles, chips, strands or sheets may then be gathered in an assembly and subjected to curing conditions whereby the polyphenolic macromolecular compound, the polyamine functional compound and the carbohydrate are caused to react to form a macromolecular binder, and water is evaporated. The obtained product may then be further processed in suitable process steps to make intermediate or final products, including but not limited to insulation products or wood boards.

[0047] As mentioned before, preferred polyprimary amines are those in which the spacer group between two primary amines is a straight or branched alkenyl group with 2 to 25 C-atoms, preferably 4 to 25 C-atoms, or a mono- aromatic group, wherein the primary amine functional groups are bound to the aromatic group either directly or through an intermediate spacer alkylene, or a polyaromatic group, wherein the primary amine functional groups are bound to the polyaromatic group either directly or through an intermediate spacer alkylene at distant opposite positions. Examples are hexamethylenediamine, triprimary triamines, ethylene diamine, 1,3-diaminopropane, cadaverine, putrescine, 1,7-diaminoheptane, 1,8-diaminooctane, 2,2,4-trimethylhexamethylenediamine, diaminotoluene, benzidine, or mixtures thereof.

[0048] Curing may be performed at a temperature ranging from ambient to 280 °C, preferably higher than 100 °C, more preferably higher than 140 °C, preferably lower than 250 °C, typically between 160 and 250 °C.

[0049] The monosaccharide may be a monosaccharide in its aldose or ketose form, including a triose, a tetrose, a pentose, a hexose or a heptose, or combinations thereof. It may be a reducing sugar or one that forms a reducing sugar in situ under thermal curing conditions. When a triose is used, an aldotriose or ketotriose sugar may be used, such as glyceraldehyde or dihydroxyacetone. When a tetrose is used, aldotetrose sugars, such as erythrose and threose, or ketotetrose sugars, such as erythrulose, may be used. When pentose sugars are used, ribose, ribulose, arabinose, arabulose, xylose, xylulose, lyxose, or lyxulose, may be used. When a hexose sugar is used, dextrose, mannose, galactose, allose, altrose, talose, gulose, iodose, fructose, psicose, sorbose, or tagatose may be used. When a heptose is used, sedoheptulose may be used. The saccharide is advantageously selected from dextrose, fructose, xylose and combinations thereof.

[0050] Disaccharides may advantageously be selected from sucrose, lactose, maltose and cellobiose.

[0051] The concentration of polyphenolic macromolecular compound in the composition may vary preferably from 55 to 85 wt.%, more preferably from 55 to 80 wt.% or 60 to 75 wt.%. The polyamine functional compound may range from 2.5 to 40 wt.%, preferably from 5 to 35 wt.% or from 10 to 30 wt.%, or even 25 wt.%. Preferably, the ratio of reactive groups on the macromolecules to reactive amino groups in the amine components may be in the range of 10:1 to 1:1. The concentration of carbohydrate may vary from 5 to 45 wt.%, preferably from 10 to 30 wt.% or 10 to 25 wt.%.

[0052] Preferred binder compositions comprise a lignosulfonate salt, preferably ammonium lignosulfonate or calcium or magnesium lignosulfonate, and a diamine, such as hexamethylenediamine (HMDA).

[0053] The invention will be explained in more details in the examples below with reference to the attached Figures, in which:

[0054] Fig. 1 shows dry and wet bond strength for compositions of Example 1;

[0055] Fig. 2 shows dry and wet bond strength compared to prior art compositions; Fig. 3 shows bond strength after tropical ageing compared to prior art compositions;

[0056] Fig. 4 shows dry, wet and weathered bond strength for invention compositions comprising different polyfunctional amines;

[0057] Fig. 5 shows dry and wet bond strength of invention compositions;

[0058] Fig. 6 shows bond strength of invention compositions after tropical ageing; and

[0059] Fig. 7 shows dry and wet bond strength of alternative invention binder compositions.

[0060] Example 1: Preparation of binder compositions comprising lignosulfonates, HMDA and dextrose.

[0061] Ammonium lignosulfonate (BorreBind FL) and calcium lignosulfonate (Borresperse CAFN) were provided by Borregaard LignoTech. The amine functional material such as hexamethylene diamine (HMDA) was obtained from Aldrich.

[0062] The required amounts of lignosulfonate (LS) and carbohydrate were dissolved in water at ambient temperature. The required amount of polyamine functional compound was added to the LS / carbohydrate solution followed by homogenization.

[0063] An exemplary composition comprises 67 parts by weight ammonium-lignosulfonate, 20 parts by weight dextrose, and 13 parts by weight HMDA.

[0064] An alternative composition comprises 65 parts by weight ammonium-lignosulfonate, 20 parts by weight dextrose, and 15 parts by weight HMDA.

[0065] Another invention composition comprises 60 parts by weight ammonium-lignosulfonate, 20 parts by weight dextrose, and 20 parts by weight HMDA.

[0066] Another invention composition comprises 47 parts by weight ammonium-lignosulfonate, 30 parts by weight dextrose and 10 parts by weight starch (Stadex201), and 13 parts by weight HMDA.

[0067] In alternative compositions, the dextrose content above may be replaced by xylose, fructose, or high fructose corn syrup (e.g. HFCS 58 / 42 comprising 58 parts by dry weight of dextrose and 42 parts by dry weight of fructose).

[0068] Example 2: Bond Strength Analysis.

[0069] In order to determine the bond strength of binders, initially impregnated glass veils (nonwoven glass fibers) of A4 size were placed into a muffle furnace for 30 minutes at 600 °C in order to ensure burnout of impregnation material and thereafter cooled for 30 min. Approx. 400 g of the prepared binder solutions were poured into separate dip trays and the burnout veils were carefully totally immersed into the relevant binder solutions. The thus impregnated veils were then cured at 200 °C during 10 minutes.

[0070] The bond strength analysis was performed using a testometric machine (M350-10CT) of the binder impregnated cured veils. For each test a cured binder impregnated A4 veil was cut into 16 equal strips. Each strip was tested separately using a 50 Kg load cell (DBBMTCL-50 kg) with a test speed of 10 mm / min, controlled by winTest Analysis software. Glass veil tensile plates were attached to the testometric machine to ensure a 100 mm gap between plates. The samples were placed vertically in the grippers, within the rubber grip area, and the force tared to zero. Further, onscreen instructions were followed, and generated data reported as herein below. Various parameters such as maximum load at peak, stress at peak and modulus at peak were evaluated by the software, and data presented as an average for 16 samples with standard deviation. The average maximum load at peak / stress at peak is considered as the bond strength.

[0071] For dry bond strength analysis, the binder impregnated cured veils were allowed to cool and then subjected to the bond strength test described above.

[0072] For wet bond strength analysis, the above binder impregnated cured veils were placed in a hot water bath (Grant, Sub Aqua 18) at 80 °C for 10 minutes. Subsequently, the surface water was removed from the veils by tissue damping, and mechanical testing was performed immediately thereafter using a testometric machine (M350-10CT) as described above.

[0073] For weathered bond strength analysis, the above binder impregnated cured veils were placed in an autoclave vessel (Astell Scientific Ltd). The samples were subjected to 95% relative humidity atmosphere, in a temperature range of from 40 °C to 121 °C (full cycle), under a pressure of up to 2.1 bar for 1 hour. The samples were subsequently dried completely at room temperature for about 24 hours such that no moisture remains on the veil samples and then tested for bond strength as described above.

[0074] The gathered data is shown in Table 1 below and plotted in a diagram shown in Fig. 1.

[0075] Table 1:

[0076] Formulations Dry BS (N) Wet BS (N)

[0077] Average BS STDEV(+ / -) Average BS STDEV(+ / -) AmLS / Dex / HMDA: 67 / 20 / 13 84,18 9,44 70,06 10,86

[0078] AmLS / Dex / HMDA: 65 / 20 / 15 88,00 8,03 70,54 8,36

[0079] AmLS / Dex / HMDA: 60 / 20 / 20 91,89 11,27 67,49 7,85

[0080] AmLS / Fructose / HMDA: 94,43 12,19 60,96 10,09

[0081] 60 / 20 / 20

[0082] AmLS / Xylose / HMDA: 94,08 7,92 69,82 9,20

[0083] 60 / 20 / 20

[0084] AmLS / Maltodex / HMDA: 61,64 10,85 42,28 9,12

[0085] 60 / 20 / 20

[0086] AmLS / HFCS / HMDA 94,93 5,96 67,87 9,60

[0087] (67 / 20 / 13) As can be seen, all invention compositions show high bond strength, under dry and wet conditions. The maltodextrin-based composition shows significantly lower mechanical properties.

[0088] Example 3: Comparative experiment

[0089] Dry and wet bond strength of the first composition of Example 1 and Fig. 1 were compared to dry and wet bond strength of comparative compositions obtained as per Example 1, in which dextrose has been replaced by 2-hydroxyethyl cellulose (HEC), carboxymethyl cellulose (CMC), hydroxypropyl methylcellulose (HPMC) and Stadex201 starch (Tate & Lyle). The collected data is shown in Table 2 below and plotted into the diagram of Fig. 2. The average bond strength values for the 16 replicates are indicated in the Table and at the top of the bars in the diagram and the standard deviations are shown as well. As can be seen from Fig. 2, the dry and wet bond strength of all comparative compositions are significantly below the dry and wet bond strength of the invention composition.

[0090] EX 3.1: AmLS / Dex / HMDA (67 / 20 / 13)

[0091] EX 3.2: AmLS / HEC / HMDA (67 / 20 / 13)

[0092] EX 3.3: AmLS / CMC / HMDA (67 / 20 / 13)

[0093] EX 3.4: AmLS / HPMC / HMDA (67 / 20 / 13) EX 3.5: AmLS / Stadex201 / HMDA (67 / 20 / 13)

[0094] Table 2:

[0095] Ammonium lignosulfonate was obtained from Borregaard LignoTech, BorreBind FL Calcium lignosulfonate was obtained from Borregaard LignoTech, Borresperse CAFN HMDA was sourced from Aldrich (100% HMDA) and Arpadis (HMD 60) (60% HMDA) Dextrose was sourced from Cargill.

[0096] HEC was sourced from Sigma Aldrich (2-Hydroxyethyl cellulose, average Mw ~ 90,000; PCode: 1002101233, 434965-250G, Lot # MKBW2623V).

[0097] HPMC was sourced from Sigma Aldrich (Hydroxypropyl)methyl cellulose, average Mn ~ 10,000; PCode: 1002374793, 423238-100G, Lot # MKBX0082V.

[0098] CMC was sourced from Sigma Aldrich (Carboxymethyl cellulose sodium salt, low viscosity; PCode: 1002333218, C5678-500G, Lot # SLBS0175V.).

[0099] Stadex 201 was sourced from Tate & Lyle (Waxy Dextrin, Lot # SA14100194).

[0100] The bond strength after tropical ageing was established as follows: A cooling incubator with controlled humidity and temperature (Memmert GmbH, UK) was used to carry out tropical ageing of the cured binder veil samples for subsequent strength testing. Cured binder impregnated veils were conditioned at 90% ± 1% humidity and at 60gC ± 0.1gC temperature for 7 days, 28 days and 56 days, at a pressure of 1.014 bar. The tropically aged samples were tested for tensile strength using testometric machine (M350-10CT). The veils were tested after being removed from the incubator without being dried and thus contained moisture, and the results averaged over 16 replicates were compared with those of non-tropically treated veil samples. The data recorded is shown in Table 3 below and has been plotted in the diagram of Fig. 3. Table 3:

[0101] Looking at the tropical ageing data in Table 3 and Fig.3, the bond strength after 7-, 28- and 56- days tropical ageing of the comparative compositions perform less well than that of the invention compositions.

[0102] Example 4:

[0103] The recipe of Example 1 was repeated to form a binder composition comprising 67 parts by weight of calcium lignosulfonate, 20 parts by weight dextrose and 13 parts by weight HMDA, and a binder composition comprising 67 parts by weight of calcium lignosulfonate, 20 parts by weight high fructose corn syrup and 13 parts by weight HMDA. The dry and weathered bond strength are shown in Table 4 below and in Fig. 4.

[0104] Table 4:

[0105] Formulation Dry BS (N) Wet BS (N)

[0106] Average BS (N) STDEV(+ / -) Average BS (N) STDEV(+ / -)

[0107] CaLS / Dextrose / HMDA 72,30 6,21 49,64 6,57

[0108] (67 / 20 / 13)

[0109] CaLS / HFCS / HMDA 67,56 6,55 56,06 9,33

[0110] (67 / 20 / 13) The components were sourced as above and same as above. HFCS was sourced from ADM,

[0111] Isoglucose 111, with a ratio of fructose / dextrose of 42 / 58. Example 5:

[0112] The recipe of Example 1 was repeated to form a binder composition 6.1 comprising 67 parts by weight of ammonium lignosulfonate, 20 parts by weight dextrose and 13 parts by weight HMDA, and a binder composition 6.2 comprising 65 parts by weight of ammonium lignosulfonate, 20 parts by weight dextrose syrup and 15 parts by weight HMDA. The bond strength has been determined after 7days, 28 days and 56 days under tropical ageing conditions. The generated data is shown in Table 5 below and in Fig. 5.

[0113] Table 5:

[0114] Ex Dry BS 7 28 56

[0115] (N) Day Day Day

[0116] TA TA TA

[0117] Average STDEV(+ / -) Average STDEV(+ / -) Average STDEV(+ / -) Average STDEV(+ / -)

[0118] BS (N) BS (N) BS (N) BS (N) .1 82,66 6,67 53,85 5,77 53,67 5,14 66,41 6,71 .2 85,81 8,97 62,56 7,18 69,01 7,84

[0119] Example 6:

[0120] Further invention binder compositions were prepared by following the protocol of Example 1 in which ammonium lignosulfonate was replaced by calcium lignosulfonate and HMDA was replaced by TAN (Ascend Performance Materials Inc, - Hexatran™ 100). The relevant binder compositions were applied onto a substrate as explained above which was the subjected to dry and wet bond strength determination as per above protocols. The data were gathered in Table 6 below and plotted into the diagram of Fig. 6.

[0121] Table 6:

[0122] Formulation Dry BS (N) Wet BS (N)

[0123] Average BS (N) STDEV(+ / -) Average BS (N) STDEV(+ / -)

[0124] CaLS / TAN (80 / 20) 45,04 6,98 31,32 3,95

[0125] CaLS / Dextrose / TAN 85,05 4,85 66,72 8,64

[0126] (60 / 20 / 20) Example 7:

[0127] The following binder compositions were prepared following the protocol of Example 1 but with varying amines. The ammonium lignosulfonate is ARBO T5 (Tembec). The binder composition comprises 60 wt% ammonium lignosulfonate, 20 wt % dextrose monohydrate (sourced from Cargill) and 20 wt% amine. Dry bond strength, weathered bond strength and wet bond strength are shown in Table 7 below.

[0128] Table 7

[0129] Example 8:

[0130] The following binder compositions were prepared following the protocol of Example 1 but with a different amine. The ammonium lignosulfonate is from Rayonier Advanced Materials (RYAM). The binder composition comprises 60 wt% ammonium lignosulfonate, 20 wt % dextrose monohydrate (sourced from Cargill) and 20 wt% amine. The following amine was tested: K54 (tris-2, 4, 6- dimethylaminomethyl phenol). Dry bond strength is shown in Table 8 below.

[0131] Table 8 Example 9: Preparation of a composite wood board

[0132] Wood in the form of assorted pine wood shavings was purchased and used as received. The wood was placed in a plastic container and a binder solution prepared in accordance with Example 1, at 80 w% solids (determined as bake out solids after drying at 140 °C for 2 hours), was sprayed onto the wood sample, during which the wood was gently tumbled in order to become uniformly coated.

[0133] Samples of resinated wood were placed in a collapsible frame and compressed between heatable plates at approx. 2000 kPa, during 25 to 30 minutes, and maintained at about 80 °C. The obtained board sample was well-bonded internally, smooth surfaced, mechanically strong and water-resistant in the absence of any hydrophobic or other additive other than the main binder components. Estimated binder content: approx. 13 w%.

Claims

Claims1. An aqueous curable binder composition comprising more than 50 - 90 wt.% of a polyphenolic macromolecular compound, a polyamine functional compound which is a polyprimary amine comprising two or more primary amine functional groups and a carbohydrate selected from monosaccharide, disaccharide, trisaccharides, tetrasacharides, pentasaccharides and / or reaction products thereof.

2. The aqueous curable binder composition of claim 1 wherein the polyphenolic macromolecular compound is an essentially natural macromolecular compound or a macromolecular compound derived from a natural macromolecular compound, which bears a multitude of phenol or polyhydroxybenzene radicals, such as catechol radicals.

3. The aqueous curable binder composition of claim 1 or 2 wherein the polyphenolic macromolecular compound is selected from lignins, lignosulfonate salts and condensed tannins and mixtures thereof.

4. The aqueous curable binder composition of any one of the preceding claims wherein the polyphenolic macromolecular compound is a lignosulfonate salt selected from calcium lignosulfonate, sodium lignosulfonate, potassium lignosulfonate, ammonium lignosulfonate, magnesium lignosulfonate and mixtures thereof.

5. The aqueous curable binder composition of any of claims 1 to 4 wherein the polyamine functional compound is selected from diamines, triamines, tetramines, pentamines and polymeric plolyamines.

6. The aqueous curable binder composition of claim 5 wherein the spacer group between two primary amines is a straight or branched alkenyl group with 2 to 25 C-atoms, preferably 4 to 25 C- atoms, or a mono- aromatic group, wherein the primary amine functional groups are bound to the aromatic group either directly or through an intermediate spacer alkylene, or a polyaromatic group, wherein the primary amine functional groups are bound to the polyaromatic group either directly or through an intermediate spacer alkylene at distant opposite positions.

7. The aqueous curable binder composition of claim 6 wherein the polyamine functional compound is selected from hexamethylenediamine, triprimary triamines, ethylene diamine, 1,3- diaminopropane, cadaverine, putrescine, 1,7-diaminoheptane, 1,8-diaminooctane, 2,2,4- trimethylhexamethylenediamine, diaminotoluene, benzidine, and mixtures thereof.

8. The aqueous curable binder composition of claims 5, 6 or 7 comprising a lignosulfonate salt, preferably ammonium lignosulfonate or calcium lignosulfonate or magnesium lignosulfonate or sodium lignosulfonate or potassium lignosulfonate, and a diamine, such as hexamethylenediamine (HMDA).

9. The aqueous curable binder composition of any of the preceding claims wherein the polyphenolic macromolecular compound makes from 55 to 85 wt.%, more preferably from 55 to 80 wt.% or 60 to 75 wt.%, based on the total of the three components; the polyamine functional compound makes from 2.5 to 40 wt.%, preferably from 5 to 35 wt.% or from 10 to 30 or even to 25 wt.%, based on the total of the three components; and the carbohydrate content ranges from more than 5 to 45 wt.%, preferably from more than 5 to 40 wt.%, more preferably from 7 to 35 wt.%, more particularly from 10 to 30 wt.% or 10 to 25 wt.%, or even to 20 wt.%, based upon the total of the three components.

10. The aqueous curable binder composition of any of the preceding claims further comprising dyes, antifungal agents, antibacterial agents, hydrophobes, silicone containing coupling agents and / or other additives such as silane, dedust oil, hydrophobic polymers, thickeners and / or combinations thereof.

11. An assembly of fibers, particles, chips, strands or sheets bonded with an aqueous binder composition according to any of the preceding claims or with a binder resulting from the curing of a binder composition according to any of the preceding claims, and being (i) an insulation product, such as a mineral wool mat, or (ii) a composite wood board, such as a wood fiber board, wood particle board, plywood or similar board.

12. A process for the preparation of an assembly of fibrous or particulate materials, chips, strands or sheets wherein a combination of (i) more than 50 - 90 wt.% of a polyphenolic macromolecular compound which bears a multitude of phenol or polyhydroxybenzene radicals, such as catechol radicals (dihydroxybenzene), preferably lignins, lignosulfonate salts and condensed tannins and mixtures thereof, and (ii) a polyamine functional compound which is a polyprimary amine comprising two or more amine functional groups, and (iii) a carbohydrate selected from monosaccharide, disaccharide, trisaccharides, tetrasacharides, pentasaccharides and / or reaction products thereof, is applied in aqueous form onto a collection of fibers or particles, chips, strands or sheets, the coated fibers, particles, chips, strands or sheets are gathered in an assembly and subjected to curing conditions whereby the polyphenolic macromolecular compound, the polyamine functional compound and the carbohydrate are caused to react to form a macromolecular binder, and water is evaporated.

13. The process according to claim 12 characterized in that curing is performed at a temperature ranging from 60 °C - 280 °C, or from 90 °C - 200 °C, preferably higher than 140 °C, more preferably lower than 190 °C, typically between 160 and 180 °C.

14. The process of any of claims 12 to 13 wherein the aqueous binder composition is applied by spraying onto the collection of fibers, particles, chips, strands or sheets.

15. The process of any of claims 12 to 13 wherein the assembly is(i) a wood fiber board or wood particle board or similar wood board, subjected to pressing during curing;(ii) an insulation product, such as a mineral wool mat.

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