EP4626944A1

EP4626944A1 - Sustainable wood adhesive formulation

Info

Publication number: EP4626944A1
Application number: EP23809214.2A
Authority: EP
Inventors: Tine VIERENDEEL; Servaas Holvoet
Original assignee: Huntsman International LLC
Current assignee: Huntsman International LLC
Priority date: 2022-11-30
Filing date: 2023-11-20
Publication date: 2025-10-08
Also published as: MX2025006239A; WO2024115164A1; CN120322473A

Abstract

A formulation comprising at least one isocyanate compound; at least one bio-oil based compound selected from triglyceride (TG) based bio-oil compounds and esterified bio-based fatty acid compounds, optionally a catalyst compound to promote the urea/urethane formation and optionally further auxiliary compounds and/or additives wherein the ratio TG based bio-oil compounds towards esterified fatty acid compounds is in the range 60/40 up to 0/100, preferably in the range 55/45 up to 0/100, more preferably in the range 50/50 up to 40/60, most preferred a ratio of 45/55 up to 50/50, and the at least one isocyanate compound (a) is present in an amount of at least 90 % by weight based on 100% by weight of the total formulation.

Description

SUSTAINABLE WOOD ADHESIVE FORMULATION FIELD OF INVENTION The present invention is related to a sustainable isocyanate based formulation or composition suitable as wood adhesive composition which provides cohesive strength to wood particles, flakes or fibers and enables the production of wood composite panels such as Particle Boards (PB), Oriented Strand Boards (OSB) and Wood Fibre Insulation (WFI) panels. The invention further relates to a sustainable isocyanate based formulation or composition which comprises an isocyanate fraction and a significant bio based fraction. In particular, the present invention provides an isocyanate based formulation which is storage stable in time and which may comprise up to 25 wt% bio-based compounds (calculated on the total weight of the formulation) selected from triglyceride based bio-oil and/or esterified fatty acids. The present invention further relates to a method for preparing the sustainable isocyanate formulation according to the invention and the use of said formulation as wood adhesive and a lignocellulosic body prepared using said wood adhesive. BACKGROUND Amino resins, such as urea-formaldehyde based resins (UF), are the most widely used wood adhesives, particularly for particle board manufacturing, because of their low cost and high cure speeds. However, beside the environmental and health issues, these UF based resins are subject to hydrolytic degradation when in the presence of moisture and/or acids. This degradation is mainly due to the hydrolysis of the amino plastic and the methylene bridges. Typically, the addition of isocyanates, such as methylene diphenyl diisocyanate (MDI), to UF resins is done to improve the latter’s performance in terms of hydrolytic stability and mechanical performances such as minimum strength, modulus, compression hardness and thickness swells, and formaldehyde emissions. Isocyanate based resins as such are also widely used as wood adhesives and nowadays bio- based materials are commonly introduced in the market in order to improve sustainability and reduce the environmental footprint of resins. Isocyanate based resins show however poor miscibility characteristics with bio-based materials such as triglyceride based bio-oil compounds upon blending/mixing. As a consequence, the amount of said bio-based compounds in the isocyanate based resins is limited because phase separation may occur in the mix yielding bio-oil enriched regions. Poor miscibility of the components may also lead to adhesives with decreased and inconsistent performance towards reactivity and lower degrees of conversion/crosslinking. Phase separation also influences the kinetics of the gluing. Several approaches have been previously explored to maximize the amount of bio-oil based compounds and minimize the poor miscibility characteristics. Currently, partial solutions are available. For example, using surfactants to improve miscibility, e.g. silicones. This solution is however not preferred because of plasticization issues, fugitivity of the surfactant (migration to surface), post-production paintability, and potential adhesion/release issues. Another approach is based on the use of specialized mixing configurations (high shear, ultrasonic mixing, etc.) and/or using higher mixing energies in order to better homogenize isocyanate droplets with the bio-oil based compounds. This solution is also not preferred because special mixing devices/configurations are necessary. Moreover, the mixture may only have limited pot life Another approach is to prepolymerize the isocyanates with an iso-reactive bio component such as a bio-based polyol. However, this leads to higher viscosity resins which do not allow smooth processing of the adhesive. A lower viscosity means that the adhesive compositions can be transferred between vessels or storage tanks more simply, by means of pumps, for example, and are easier to spread on the surfaces that are to be bonded. There is hence a need to develop a synthesis method to make isocyanate based adhesives having significant increased amounts of bio-oil based compounds thereby avoiding the problem of poor miscibility and thereby maintaining the shelf-life and adhesive properties of isocyanate based adhesives having no bio-based oil compounds. GOAL OF THE INVENTION It is the goal of the invention to develop a synthesis method to provide isocyanate based resins for use as wood adhesives wherein said resin has a significant amount of bio-oil based compounds, in particular having up to 25 wt% and higher bio-oil based compounds calculated on the total weight of the resin. It is an object of the present invention to provide an adhesive formulation having 10-25 wt% bio-oil based compounds (calculated on the total weight of the resin) having stability, good processing properties and being capable of further processing to give wood-based materials having a good performance profile, the requirement being in particular for high mechanical load-bearing properties of wood-based materials. The present inventors have now surprisingly found that this goals can be achieved by a formulation comprising at least one isocyanate compound and up to 25 wt% bio-oil based compounds wherein the bio-oil based compounds are selected from triglyceride (TG) based bio-oil compounds and esterified fatty acid compounds and wherein the ratio TG based bio oil compounds towards esterified bio-based fatty acid compounds is in the range 60/40 up to 0/100, preferably in the range 55/45 up to 0/100, more preferably in the range 50/50 up to 40/60, most preferred a ratio of 45/55 up to 50/50. This formulation provides very good miscibility of the bio-oil based compounds with the isocyanate compounds which is stable in time (good shelf life) and has processing characteristics comparable to isocyanate-based wood adhesive formulations without addition of bio-oil based compounds such as speed and key panel characteristics (adhesive strength, limited swell etc.). A better miscible and more compatible system ameliorates the overall performance of such hybrid adhesive systems. Therefore, the present invention relates to isocyanate based resins having 10-25 wt% bio- oil based compounds and the use of these isocyanate based resins as a wood adhesive composition which provides cohesive strength to wood particles, flakes or fibers and enables the production of wood composite panels such as Particle Boards (PB), Oriented Strand Boards (OSB) and Wood Fibre Insulation (WFI) panels. DEFINITIONS AND TERMS In the context of the present invention the following terms have the following meaning: 1) The term “isocyanate index” or “NCO index” or “index” as used herein means the ratio of NCO-groups over isocyanate-reactive hydrogen atoms present in a formulation, given as a percentage : [NCO] x 100 (%). [active hydrogen] In other words the NCO-index expresses the percentage of isocyanate actually used in a formulation with respect to the amount of isocyanate theoretically required for reacting with the amount of isocyanate-reactive hydrogen used in a formulation. The NCO value as indicated in the examples is measured using a measurement method based on titration. The isocyanate is reacted with an excess of di-n- butylamine to form ureas. The unreacted amine is then titrated with standard nitric acid to the colour change of bromocresol green indicator or to a potentiometric endpoint. The percent NCO or NCO-value is defined as the percent by weight of NCO-groups present in the product. Further, it should be observed that the isocyanate index as used herein is considered from the point of view of the actual polymerisation process preparing the material involving the isocyanate ingredient and the isocyanate- reactive ingredients. Any isocyanate groups consumed in a preliminary step to produce modified polyisocyanates (including such isocyanate-derivatives referred to in the art as prepolymers) or any active hydrogens consumed in a preliminary step (e.g. reacted with isocyanate to produce modified polyols or polyamines) are not taken into account in the calculation of the isocyanate index. Only the free isocyanate groups and the free isocyanate-reactive hydrogens (including those of water, if used) present at the actual polymerisation stage are taken into account. 2) A triglyceride (TG) as referred to herein is defined as an ester derived from glycerol and three carboxylic acids having aliphatic chains with an even number of 4 to 28 carbon atoms per molecule. Carboxylic acids having aliphatic chains with an even number of 4 to 28 carbon atoms per molecule are commonly known as fatty acids. Triglycerides often are formed from fatty acids with 16 or 18 carbon molecules per aliphatic chain. Triglycerides that are useful in the present invention can be vegetable oils. The vegetable oils can be partially or fully hydrogenated, or can be used without hydrogenation. Examples of vegetable oils include, but are not limited to soybean oil, rapeseed oil, sunflower oil, canola oil, safflower oil, menhaden oil, corn oil, olive oil, cacao oil, linseed oil, cottonseed oil, peanut oil, palm oil, jatropha oil, algal oil, coconut oil, and mixtures thereof. 3) The expression “Mode of Elasticity” or “MOE” and “Mode of Rupture” or “MOR” as used herein is expressed in MPa and is measured according to BS 310: Determination of the modulus of elasticity in banding and of bending strength. The mode (modulus) of elasticity in bending and bending strength are determined by applying a load to the center of a test piece supported at two points. The modulus of elasticity is calculated by using the slope of the linear region of the load-deflection curve; the value calculated is the apparent modulus, not the true modulus, because the test method includes shear as well as bending. The bending strength of each test piece is calculated by determining the ratio of the bending moment M, at the maximum load F^max, to the moment of its full cross section. 4) The expression “Tensile strength” as used herein refers to “Internal Bond (IB) strength” and is expressed in MPa and measured according to BS 319: Determination of tensile strength perpendicular to the plane of the board. Determination of resistance to tension perpendicular to the surface of the test piece by submitting the latter to a uniformly distributed tensile force until rupture occurs. Tensile strength perpendicular to the plane of the board is determined by the maximum load in relation to the surface area of the test piece. 5) The expression “Thickness swell” as used herein is expressed in % and is measured according to BE EN 317: Determination of swelling in thickness after i^{mmersion in water for a predefined time.} ^{the increase in thickness of the test piece after complete immersion} in water. 6) The expression “press factor” as used herein is calculated in s/mm and refers to the time the panel is in the press at certain temperature and for a certain panel thickness. 7) The expressions “isocyanate-reactive compounds”, “NCO-reactive compounds” “isocyanate-reactive hydrogen atoms” and “isocyanate- reactive groups” as used herein refer to active hydrogen atoms in hydroxyl and amine groups present in the isocyanate reactive compounds. Compounds having one hydroxyl group are considered to comprise one reactive hydrogen, compounds having one primary amine group are considered to comprise one reactive hydrogen and one water molecule is considered to comprise two active hydrogens. 8) The word “average” as used herein refers to number average unless indicated otherwise. 9) A “fatty acid” as referred to herein is a carboxylic acid with an aliphatic chain, which may be saturated or unsaturated. A “bio-based fatty acid” is a fatty acid originating from naturally occurring fatty acids. The fatty acid according to the invention preferably has an unbranched chain of 4 up to 28 carbon atoms. 10) An “esterified fatty acid” or “Fatty acid ester” as referred to herein is the reaction product of a fatty acid with an alcohol. A “bio-based esterified fatty acid” as referred to herein is an esterified fatty acid originating from naturally occurring fatty acids. An example of a suitable esterified fatty acid is methyl linoleate (also referred to as linoleic acid methyl ester), a common methyl ester produced from soybean or canola oil and methanol. Another suitable example of an esterified fatty acid is rapeseed methyl ester (RME) which is the reaction product of the naturally occurring fatty acids in rapeseed oil with methanol. DETAILED DESCRIPTION The present invention will be described with respect to particular embodiments. It is to be noticed that the term "comprising", used in the claims, should not be interpreted as being restricted to the means listed thereafter; it does not exclude other elements or steps. It is thus to be interpreted as specifying the presence of the stated features, steps or components as referred to, but does not preclude the presence or addition of one or more other features, steps or components, or groups thereof. Thus, the scope of the expression "a compound comprising components X and Y" should not be limited to compounds consisting only of components X and Y. It means that with respect to the present invention, the only relevant components of the compound are X and Y. Throughout this specification, reference to "one embodiment" or "an embodiment" are made. Such references indicate that a particular feature, described in relation to the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment, though they could. Furthermore, the particular features or characteristics may be combined in any suitable manner in one or more embodiments, as would be apparent to one of ordinary skill in the art. It is to be understood that although preferred embodiments and/or materials have been discussed for providing embodiments according to the present invention, various modifications or changes may be made without departing from the scope and spirit of this invention. According to the invention, a stable isocyanate based formulation suitable as wood adhesive is disclosed wherein said formulation comprises up to 25 wt% bio-oil based compounds selected from triglyceride (TG) based bio-oil compounds and esterified bio- based fatty acid compounds and wherein the ratio TG based bio oil compounds towards esterified fatty acid compounds is below 60/40, preferably in the range 55/45 up to 0/100, more preferably in the range 40/60 up to 50/50, most preferred a ratio of 50/50. Therefore, the present invention provides a formulation comprising: - at least one isocyanate compound; and - at least one bio-oil based compound selected from triglyceride (TG) based bio-oil compounds and esterified bio-based fatty acid compounds, and - optionally a catalyst to promote the urea/urethane formation - optionally further auxiliary compounds and/or additives. characterized in that the ratio TG based bio-oil compounds towards esterified fatty acid compounds is below 60/40, preferably in the range 55/45 up to 0/100, more preferably in the range 40/60 up to 50/50, most preferred a ratio of 50/50. According to embodiments, the amount of TG based bio oil compounds in the formulation according to the invention is 0 wt% up to 60 wt%, preferably 0 wt% up to 55 wt%, more preferably 40 wt% up to 50 wt% based on the total weight of all bio-oil based compound selected from triglyceride (TG) based bio-oil compounds and esterified bio-based fatty acid compounds in the formulation. According to embodiments the amount of TG based bio oil compounds in the formulation according to the invention is 10 wt% up to 55 wt%, preferably 20 wt% up to 55 wt%, more preferably 40 wt% up to 50 wt% based on the total weight of all bio-oil based compound selected from triglyceride (TG) based bio-oil compounds and esterified bio-based fatty acid compounds in the formulation. According to embodiments, the amount of TG based bio oil compounds in the formulation according to the invention is 50 wt% based on the total weight of all bio-oil based compound selected from triglyceride (TG) based bio-oil compounds and esterified bio- based fatty acid compounds in the formulation. According to embodiments, the formulation according to the invention contains only esterified bio-based fatty acid compounds and no TG based bio oil compounds. The formulation according to the invention is suitable as an adhesive and allows retention of processing, speed and key panel characteristics (such as but not limited to adhesive strength, avoidance of swell, moisture resistance, etc.) The formulation according to the invention is comprises a significant amount of bio-based compounds originating from bio-oils and is due to its specific ratio TG based bio-oil compounds towards esterified fatty acid compounds characterized as a stable formulation having desired viscosity properties (being < 150-160 mPa.s) and not leading to phase separation. Typically, a lower viscosity leads to a better distribution of the adhesive formulation on the wood. The formulation according to the invention is further characterized as having a lower density compared to state of the art isocyanate based adhesives, thereby leading to a larger volume of binder applied to the wood when applied at a similar loading in weight. The at least one isocyanate compound of the formulation according to the invention comprises at least one isocyanate. In an embodiment, the at least one isocyanate comprises a polyisocyanate compound. Non-limiting examples of suitable polyisocyanates that can be used in the present invention can be any organic polyisocyanate compound or mixture of organic polyisocyanate compounds, preferably wherein said compounds have at least two isocyanate groups. Non-limiting examples of organic polyisocyanates include diisocyanates, particularly aromatic diisocyanates, and isocyanates of higher functionality. Non-limiting examples of organic polyisocyanates which may be used in the formulation of the present invention include aliphatic isocyanates such as hexamethylene diisocyanate; and aromatic isocyanates such as diphenylmethane diisocyanate (MDI) in the form of its 2,4' , 2,2' and 4,4' isomers and mixtures thereof (also referred to as pure MDI), the mixtures of diphenylmethane diisocyanates (MDI) and oligomers thereof (known in the art as "crude" or polymeric MDI), m- and p-phenylene diisocyanate, tolylene-2,4- and tolylene- 2,6-diisocyanate (also known as toluene diisocyanate, and referred to as TDI, such as 2,4- TDI and 2,6-TDI) in any suitable isomer mixture, chlorophenylene-2,4-diisocyanate, naphthylene-1,5-diisocyanate, diphenylene-4,4'-diisocyanate, 4,4'-diisocyanate-3,3'- dimethyl-diphenyl, 3-methyl-diphenylmethane-4,4'-diisocyanate and diphenyl ether diisocyanate; and cycloaliphatic diisocyanates such as cyclohexane-2,4- and -2,3- diisocyanate, 1-methylcyclohexyl-2,4- and -2,6-diisocyanate and mixtures thereof and bis- (isocyanatocyclohexyl)methane (e.g.4,4’-diisocyanatodicyclohexylmethane (H12MDI)), triisocyanates such as 2,4,6-triisocyanatotoluene and 2,4,4-triisocyanatodiphenylether, isophorone diisocyanate (IPDI), butylene diisocyanate, trimethylhexamethylene diisocyanate, isocyanatomethyl-1,8-octane diisocyanate, tetramethylxylene diisocyanate (TMXDI), 1,4-cyclohexanediisocyanate (CDI), and tolidine diisocyanate (TODI). In an embodiment, the at least one isocyanate can be an emulsifiable polyisocyanate. Suitable emulsifiable isocyanate can be any kind of emulsifiable MDI, such as those disclosed in the following patent publications: EP 18061, EP 516361, GB 1523601, GB 1444933, GB 2018796, all incorporated herein by reference. A suitable class of emulsifiable MDI comprises those products obtained by pre-reacting a polyisocyanate, especially polymeric MDI, with a minor proportion of an alkoxypolyalkylene glycol (e.g. one in which one of the glycol -OH groups has been converted to an alkoxy group, for example by reaction with a lower alcohol such as methanol and/or ethanol), such products being mixtures of the polyisocyanate and a minor proportion of a nonionic surfactant formed by reaction between the polyisocyanate and the alkoxypolyalkylene glycol. The self-emulsifiable polyisocyanate may be based on any organic polyisocyanate, for example low functionality MDI variants such as uretonimine modified MDI, but is preferably based on the mixtures known as polymethylene polyphenyl polyisocyanates or polymeric MDI. Alkoxypolyalkylene glycols which may be reacted with the polyisocyanate to form the self-emulsifiable polyisocyanate include alkoxypolyethylene glycols, such as those having molecular weights in the range 250 to 4000, particularly 600 to 2000. The alkoxy group suitably contains from one to six carbon atoms, the methoxypolyethylene glycols being preferred. Suitable emulsifiable polyisocyanates are commercially available from Huntsman under the trade names Suprasec^® 1042, Suprasec^® 2405, Suprasec^® 2408 and Suprasec^® 2419 (Suprasec^® is a trademark of Huntsman LLC). In an embodiment, the at least one isocyanate can be selected from 2,4'-, 2,2'- and 4,4'-MDI isomers, homopolymers and mixtures thereof, mixtures of 2,4', 2,2' and 4,4' methylene diphenyl diisocyanate and oligomers thereof. In an embodiment, the at least one isocyanate is selected from the group comprising 2,2'- or 4,4'-MDI, homopolymers and mixtures thereof, or mixtures of 2,2' and 4,4' methylene diphenyl diisocyanate and oligomers thereof. In an embodiment, the at least one isocyanate is selected from 4,4'-MDI or homopolymers thereof.

Preferred polyisocyanate compositions of the present invention are those wherein the polyisocyanate is an aromatic diisocyanate or polyisocyanate of higher functionality in particular crude mixtures of methylene bridged polyphenyl polyisocyanates containing diisocyanates, triisocyanate and higher functionality polyisocyanates. Methylene bridged polyphenyl poly isocyanates (e.g. Methylene diphenyl diisocyanate, abbreviated as MDI) are well known in the art and have the generic formula I wherein n is one or more and in the case of the crude mixtures represents an average of more than one. They are prepared by phosgenation of corresponding mixtures of polyamines obtained by condensation of aniline and formaldehyde.

Other suitable polyisocyanate compositions may include isocyanate ended prepolymers made by reaction of an excess of a diisocyanate or higher functionality poly isocyanate with a hydroxyl ended polyester or hydroxyl ended polyether and products obtained by reacting an excess of diisocyanate or higher functionality polyisocyanate with a monomeric polyol or mixture of monomeric polyols such as ethylene glycol, trimethylol propane or butanediol. One preferred class of isocyanate-ended prepolymers are the isocyanate ended prepolymers of the crude mixtures of methylene bridged polyphenyl polyisocyanates containing diisocyanates, triisocyanates and higher functionality polyisocyanates. Preferred prepolymers are those whose NCO content is from 5 to 30 %, preferably from 10 to 28 %, with particular preference from 15 to 25 % by weight. Their viscosity at 25° C is from 300 to 10000, preferably from 500 to 2000 mPa.s. The polyisocyanate mixture may be produced in accordance with any of the techniques known in the art. The isomer content of the diphenylmethane diisocyanate may be brought within the required ranges, if necessary, by techniques which are well known in the art. One technique for changing isomer content is to add monomeric MDI to a mixture of MDI containing an amount of polymeric MDI which is higher than desired. In an embodiment, the at least one isocyanate comprises any suitable mixture of any polyisocyanate described above, or any suitable mixture of one or more of the polyisocyanates described above with MDI-type polyisocyanates. In some embodiments, the at least one isocyanate can be present in an amount of at least 70 % by weight, based on 100% by weight of the total formulation. For example, the at least one isocyanate can be present in the formulation in an amount of at least 75% by weight, for example in an amount of at least 80% by weight, for example in an amount of at least 85% by weight based on the total weight (100%) of the formulation. For example, the at least one isocyanate can be present in an amount of from 70 to 90 % by weight, for example from 75 to 85 % by weight, for example from 75 to 80 % by weight, for example from 75 to 80 % by weight based on the 100% by weight of the total formulation. According to embodiments, the triglyceride (TG) based bio-oil compounds are selected from linseed oil, soybean oil, palm kernel oil, sunflower oil, corn oil, cottonseed oil, perilla oil, rapeseed oil, olive oil and/or canola oil, palm oil, coconut oil, rice bran oil, safflower oil, sesame oil, tall oil, and mixtures thereof Examples of bio-based fatty acids originating from bio-oil and suitable for making to make the esterified fatty acid compounds are caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid, lignoceric acid, cerotic acid, myristoleic acid, palmitoleic acid, sapienic acid, oleic acid, elaidic acid, vaccenic acid, linoleic acid, linoelaidic acid, (α)-linolenic acid, arachidonic acid, eicosapentaenoic acid, erucic acid, docosahexaenoic acid. According to preferred embodiments, the bio-based fatty acid used to make the esterified fatty acid compounds include, but are not limited to caprylic acid, capric acid, lauric acid, palmitic acid, stearic acid, arachidic acid, behenic acid, lignoceric acid, palmitoleic acid, linoleic acid, linolenic acid, oleic acid, erucic acid, and combinations thereof. Preferred esterified fatty acid compounds are originating from linoleic acid, linolenic acid and oleic acid. A suitable example of an esterified bio-based fatty acid compound is a methyl ester mixture of saturated and unsaturated C16 to C22 fatty acids originating from rapeseed oil, also referred to as Rapeseed Methyl Ester (RME). In some embodiments, the formulation can further comprise at least one additive selected from the group comprising a hardener, a surfactant, a release agent, a wax, or a pigment. In some embodiments, the additive can be present in an amount of at least 0.01% by weight, for example at least 0.03% by weight, for example at least 0.1% by weight, preferably at least 0.3% by weight, preferably at least 1% by weight based on the total weight (100%) of the formulation. In an embodiment, said additive is a surfactant. A non-limiting example of a surfactant is silicone. Non-limiting examples of waxes are slack wax or emulsion wax. Non-limiting examples of suitable pigments comprise titanium dioxide, zinc borax, oxalates, mica, perlite, clays, and silicon dioxide. According to embodiments, said additive is a hardener, also referred to as a polyurethane forming catalyst compound. Polyurethane forming catalyst compounds suitable for use herein include, but are not limited to, metal salt catalysts, such as organotins, and aliphatic and aromatic tertiary amine compounds, such as triethylenediamine (TEDA), N- methylimidazole, 1,2-dimethylimidazole, N-methylmorpholine, N-ethylmorpholine, triethylamine, N,N'-dimethylpiperazine, 1,3,5- tris(dimethylaminopropyl)hexahydrotriazine, 2,4,6-tris(dimethylaminomethyl)phenol, N,N-dimethylcyclohexylamine, pentamethyldipropylene triamine, N-methyl-N'-(2- dimethylamino)-ethyl-piperazine, tributylamine, pentamethyldiethylenetriamine, hexamethyltriethylenetetramine, heptamethyltetraethylenepentamine, dimethylaminocyclohexylamine, pentamethyldipropylene-triamine, triethanolamine, dimethylethanolamine, bis(dimethylaminoethyl)ether, tris(3-dimethylamino)propylamine, or its acid blocked derivatives, and the like, as well as any mixture thereof. The catalyst compound should be present in a catalytically effective amount. The present invention also encompasses a method for preparing a formulation as described above, comprising the steps of mixing the at least one isocyanate compound, the at least one bio-oil based compound selected from triglyceride (TG) based bio-oil compounds and esterified fatty acid compounds, optionally a catalyst to promote the urea/urethane formation and optionally further auxiliary compounds and/or additives as described above thereby obtaining a formulation as described above. The present invention also encompasses the use of the formulation or composition according to the invention as an adhesive. The formulation or composition can be particularly useful as an adhesive for a material comprising lignocellulose, herein also referred to as a "lignocellulosic material". Non-limiting examples of lignocellulosic materials comprise wood strands, woodchips, wood fibers, shavings, veneers, wood wool, cork, bark, sawdust and like waste products of the wood working industry as well as other materials having a lignocellulosic basis such as paper, bagasse, straw, flax, sisal, bamboo, coconut fibers, hemp, rushes, reeds, rice hulls, husks, grass, nutshells and the like. Additionally, the lignocellulosic material may be mixed with other particulate or fibrous materials such as grinded foam waste (for example, grinded polyurethane foam waste), mineral fillers, glass fiber, mica, rubber, textile waste such as plastic fibers and fabrics. The lignocellulosic material may be used in the form of granulates, shavings or chips, fibers, strands, spheres or powder. Preferably, the lignocellulosic material comprises wood. The present invention also encompasses the use of the formulation or composition according to the invention for bonding at least one lignocellulose containing product, herein also referred to as a "lignocellulosic body". The formulations or compositions according to the invention can also be particularly useful for repairing a lignocellulosic body. The present invention also encompasses a process for bonding lignocellulosic materials comprising coating the lignocellulosic materials with a formulation or composition according to the invention and curing the formulation or composition. The present invention also encompasses a substrate comprising the adhesive formulation or composition according to the invention. The present invention also encompasses the lignocellulosic comprising body prepared using the formulation or composition according to the invention. The lignocellulosic body according to the invention can be prepared by bringing the lignocellulosic material into contact with a formulation or composition according to the invention, for example by means of mixing, spraying and/or spreading the formulation or composition with/onto the lignocellulosic material and by pressing the lignocellulosic material, preferably by hot-pressing, for example at a temperature between 120°C to 300°C, preferably between 140°C to 270°C and for example at 2 to 6 MPa specific pressure. The lignocellulosic material after treatment with the formulation or composition according to the invention can be placed on caul plates made of aluminum or steel which serve to carry the furnish into the press where it is compressed to the desired extent, usually at a temperature between 120°C and 300°C, preferably between 140°C and 270°C. At the start of a manufacturing run it may be helpful, but not essential, to condition the press plates by spraying their surfaces with an external release agent or to increase the cycle time of the first press load. A preconditioned press may then be used many times in the process of the invention without further treatment. Non-limiting examples of lignocellulosic bodies include oriented strand board (OSB), structural composite lumber (SCL), waferboard, fiberboard, particle board, chipboard, medium-density fiberboard (MDF), hardboard (also called high-density fiberboard or HDF), plywood, pallet blocks and boards that are a composite of strands and ply veneers. The independent and dependent claims set out particular and preferred features of the invention. Features from the dependent claims may be combined with features of the independent or other dependent claims as appropriate. The above and other characteristics, features and advantages of the present invention will become apparent from the detailed description, taken in conjunction with the accompanying examples which illustrate the principles of the invention. EXAMPLES Compounds used: - MDI 1: I-BOND^® PB PM 4350 is a polymeric methylene diphenyl isocyanate (pMDI) with a viscosity at 25 °C of 205 mPa.s and NCO value of 30.9 % NCO. - MDI 2: I-BOND^® PB PM 4358 is a polymeric methylene diphenyl isocyanate (pMDI) with a viscosity at 25 °C of 675 mPa.s and NCO value of 30.5 % NCO. - MDI 3: I-BOND^® OSB EFC 4362 is a prepolymerised MDI with a viscosity at 25 °C of 395 mPa.s and NCO value of 27.3 % NCO. - Natural oil 1: Agri-pure^® AP-60 (Cargill) is a natural oil (rapeseed) based on refined vegetable triglycerides containing oleic, linoleic and linolenic fatty acids. Natural oil 1 has a typical viscosity lower than 50 mPa.s @ 25 °C - Fatty acid ester 1: Agri-pure^® AP-406 (Cargill) is product based on vegetable oil methyl esters from oleic, linoleic and linolenic fatty acids originating from rapeseed oil. Fatty Acid Ester 1 has a typical viscosity lower than 30 mPa.s @ 25 °C - Natural Oil 2: Agri-Pure AP^®-25 (Cargill) is a natural oil (soybean) based on refined vegetable triglycerides. Natural oil 2 has a typical viscosity lower than 50 mPa.s @ 25 °C Unless otherwise indicated, all parts and all percentages in the following examples, as well as throughout the specification, are parts by weight or percentages by weight respectively. As used herein, the term "Natural oil" refers to the weight percentage of the triglyceride (TG) based bio-oil compound in the formulation and the term “Fatty acid ester” refers to the esterified fatty acid compounds in the formulation as claimed. Adhesive formulations The isocyanate compound (MDI), triglyceride (TG) based oil compounds (natural oil) and Esterified Fatty Acid (EFA) compounds were mixed together at room temperature by use of a low power mixer (Heidolph). The triglyceride (TG) based oil compounds (natural oil) and Esterified Fatty Acid (EFA) compounds can be mixed upfront or added separate (if separate addition, first the Esterified Fatty Acid (EFA) compounds needs to be added to the MDI, afterwards the natural oil. The mixtures were stored at room temperature and the appearance, NCO and Viscosity were measured. In Table 1 the formulations with different weight ratios of the different compounds are listed. Resins 1, 2 and 3 are reference formulations according to the state of the art containing no bio-based compounds. The resins showing clear separation (not a stable formation) are outside the claimed formulation and not suitable as adhesive. Oriented Strand Boards (OSB) made using the adhesive formulations according to the invention (Table 2) Resins 1, 2, 7, 9 and 15 were used as an adhesive formulation to make OSB panels. Finally, after cooling and conditioning at 23°C and 50% relative humidity, the panels were cut to 5x5 cm² samples which enabled further characterization. Both layers, face and core, are glued separate. MDI loading for both layers was 3 % Laydown is done manually by first divide evenly the glued face layer material in the pre- mat mould, then spread the glued core flakes on top of the face layer as equal as possible and then divide the second face layer material evenly on top of the core layer. The pre-mat is “pre-pressed” manually by using a metal plate. The target density of the panel was 650 kg/m³. The mould is removed and the 3 layer panel is put in the press (Höfer press). Panel is pressed at elevated temperature (220°C) for a certain time (Press Factor). Finally, after cooling and conditioning at 23°C and 50% relative humidity, the panels were cut to 5x5 cm² samples which enabled further characterization. Thickness swell was measured according to standard BS 317. Internal bond strength IB V20 (dry strength) and V100 (wet strength) was measured according to standard BS 319. All values described in Table 2 are the average results of 8 cut samples. Particle Board Fabrication using the adhesive formulations according to the invention (Table 3) Resins 1, 3, 15 and 27 were used as an adhesive formulation to make a Particle Board. A Particle Board (PB) is a 3 layer board where the face layer (2) exists out of very fine particles (at a final Moisture Content (MC) of 10% by weight) and a core layer (1) which exists out of larger wood chips (at a final MC of 5 % by weight). Both layers, face and core, are glued separate. MDI loading for both layers was 3 % Laydown is done manually by first divide evenly the glued face layer material in the pre- mat mould, then spread the glued core chips on top of the face layer as equal as possible and then divide the second face layer material evenly on top of the core layer. The pre-mat is “pre-pressed” manually by using a metal plate. The target density of the panel was 650 kg/m³. The mould is removed and the 3 layer panel is put in the press (Höfer press). Panel is pressed at elevated temperature (220°C) for a certain time (Press Factor). Finally, after cooling and conditioning at 23°C and 50% relative humidity, the panels were cut to 5x5 cm² samples which enabled further characterization. Thickness swell was measured according to standard BS 317. Internal bond strength IB V20 (dry strength) was measured according to standard BS 319. Modulus of Elasticity (MOE) and Modulus of Rupture (MOR) were measured according to BS 310 and surface soundness was measured according to BS 311. All values described in Table 3 are the average results of 8 cut samples.

O^W-⁸ ₅ ¹ ₁ ⁵-^U _E ¹ ₂

Claims

CLAIMS 1. A formulation comprising following compounds: a) at least one isocyanate compound; and b) at least one bio-oil based compound selected from triglyceride (TG) based bio- oil compounds and esterified bio-based fatty acid compounds, and c) optionally a catalyst compound to promote urea/urethane formation d) optionally further auxiliary compounds and/or additives characterized in that the ratio TG based bio-oil compounds towards esterified fatty acid compounds is in the range 60/40 up to 0/100, preferably in the range 55/45 up to 0/100, more preferably in the range 50/50 up to 40/60, most preferably 45/55 up to 50/50, and the at least one isocyanate compound (a) is present in an amount of at least 90 % by weight based on 100% by weight of the total formulation

2. The formulation according to claim 1, wherein said triglyceride (TG) based bio-oil compounds are selected from linseed oil, soybean oil, palm kernel oil, sunflower oil, corn oil, cottonseed oil, perilla oil, rapeseed oil, olive oil and/or canola oil, palm oil, coconut oil, rice bran oil, safflower oil, sesame oil, tall oil, and mixtures thereof

3. The formulation according to any of foregoing claims wherein the bio-based fatty acid used to make the esterified fatty acid compounds is selected from caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid, lignoceric acid, cerotic acid, myristoleic acid, palmitoleic acid, sapienic acid, oleic acid, elaidic acid, vaccenic acid, linoleic acid, linoelaidic acid, (α)-linolenic acid, arachidonic acid, eicosapentaenoic acid, erucic acid, docosahexaenoic acid, and combinations thereof.

4. The formulation according to any of foregoing claims wherein the esterified fatty acid compound is selected from a methyl ester mixture of saturated and unsaturated C16 to C22 fatty acids originating from rapeseed oil.

5. The formulation according to any of foregoing claims wherein the amount of at least one bio-oil based compound selected from triglyceride (TG) based bio-oil compounds and esterified bio-based fatty acid compounds in the formulation is at least 10 % by weight, preferably at least 20 % by weight, more preferably at least 25 % by weight and most preferably at least 30 % by weight based on 100% by weight of the total formulation.

6. The formulation according to any of foregoing claims wherein the at least one isocyanate compound is present in an amount of at least 80% by weight, preferably at least 75% by weight, most preferably at least 70% by weight based on 100% by weight of the total formulation.

7. The formulation according to any of foregoing claims wherein the at least one isocyanate compound is selected from the group comprising hexamethylene diisocyanate, m- and p-phenylene diisocyanate, tolylene-2,4- and tolylene-2,6- diisocyanate, diphenylmethane diisocyanate in the form of its 2,4' , 2,2' and 4,4' isomers and mixtures thereof, the mixtures of diphenylmethane diisocyanates and oligomers thereof, chlorophenylene-2,4-diisocyanate, naphthylene-1,5- diisocyanate, diphenylene-4,4'-diisocyanate, 4,4'-diisocyanate-3,3'-dimethyl- diphenyl, 3-methyl-diphenylmethane-4,4'-diisocyanate, diphenyl ether diisocyanate, cyclohexane-2,4- and -2,3-diisocyanate, 1-methylcyclohexyl-2,4- and -2,6-diisocyanate, bis-(isocyana-tocyclohexyl)methane, 2,4,6- triisocyanatotoluene, 2,4,4-triisocyanatodiphenylether, isophorone diisocyanate, butylene diisocyanate, trimethylhexamethylene diisocyanate, isocyanatomethyl- 1,8-octane diisocyanate, tetramethylxylene diisocyanate, 1,4- cyclohexanediisocyanate, tolidine diisocyanate, and mixtures thereof.

8. The formulation according to any of foregoing claims wherein the at least one isocyanate compound is selected from isocyanate ended prepolymers made by reaction of an excess of a diisocyanate or higher functionality polyisocyanate with a hydroxyl ended polyester or hydroxyl ended polyether and said isocyanate ended prepolymers have an NCO content is from 5 to 30 %, preferably from 10 to 28 %, with particular preference from 15 to 25 % by weight.

9. The formulation according to any of foregoing claims wherein the catalyst compound(s) used are selected from at least a polyurethane catalyst, preferably selected from aliphatic and aromatic tertiary amines such as N,N- dimethylcyclohexylamine, organometallic compounds, especially tin compounds such as stannous octoate and dibutyltin dilaurate and alkali metal salts.

10. The formulation according to any of foregoing claims wherein the formulation comprises at least one additive selected from the group comprising a hardener, a surfactant, a release agent, a wax, and a pigment.

11. A method for making the formulation according to any of foregoing claims wherein the compounds a) and b) and optionally c) and/or d) are combined by mixing or simply shaking or by slowly stirring at room temperatures.

12. Use of a formulation according to any of claims 1 to 10 as an adhesive.

13. Use according to claim 12 for bonding at least one lignocellulosic body.