Melamine formaldehyde (MF) resin formulation comprising a nitrogencontaining aminoalkanoic acid

Abstract

The present disclosure relates to the field of melamine formaldehyde (MF) resins, their preparation and application. In particular, the instant disclosure relates to a melamine formaldehyde (MF) resin formulation comprising a condensate of formaldehyde, melamine and a biocomponent comprising a nitrogen-containing aminoalkanoic acid having at least one nitrogen on the side chain. The instant disclosure further relates to a kit comprising said MF formulation and a condensing agent, to a method for preparing said MF resin as described herein, to an impregnated cellulosic material comprising said MF resin formulation, to a cellulosic laminate comprising the same, and to a method for preparing said impregnated cellulosic material and cellulosic laminate. Nitrogen-containing aminoalkanoic acids are biological components and their presence in an MF resin formulation as described herein contribute to increasing the content of biocomponents in MF resins making them more environmentally friendly. Additionally, it has been found that the final properties of products comprising cured MF resins as described herein are not detrimentally affected by the presence of a nitrogen-containing aminoalkanoic acid, to the contrary, a biocomponent as described herein has been found to also contribute provide MF resin formulations and products comprising the same with advantageous properties.

Description

[0001] MELAMINE FORMALDEHYDE (MF) RESIN FORMULATION COMPRISING A NITROGEN¬

[0002] CONTAINING AMINOALKANOIC ACID

[0003] TECHNICAL FIELD

[0004] The present disclosure relates to the field of melamine formaldehyde (MF) resins, their preparation and application.

[0005] BACKGROUND

[0006] Melamine formaldehyde (MF) resins are widely used on cellulosic substrates in the paper and wood industries, among other, for their long-lasting and solvent-resistant properties. Some common uses of MF resins include cabinetry, laminate flooring and countertops, composites, textile finishes, surface coatings, paper binding and paper processing, and but also tires, metals, and glass modifiers. MF resins are the main constituent of high-pressure laminates (HPL), such as formica and arborite, and of laminate flooring. In such applications it is common to impregnate a decorative paper with MF resins and to laminate the impregnated paper onto a support (mainly a cellulosic substrate such as a wooden or paper support, e.g., wood boards made of wood composites or high- pressure laminates) by application of temperature and pressure in the course of which the MF resin cures to form a chemically and thermally durable top layer. Even though the two main components of MF resins are melamine and formaldehyde, the properties of the MF resins may also be modulated by the presence of additives.

[0007] For instance, European patent application published as EP0561432 describes a melamine-formaldehyde resin modified with a diamino-s-triazine, which is described to improve the processability of MF resins. British patent application published as GB1464014 describes decorative papers for laminating to chipboard or hardboard impregnated with a solution of a melamine-formaldehyde resin containing combined or added caprolactam, sucrose or an alpha-methyl glucoside, and a C 2-4 diol. Caprolactam is described to increase the stability of aqueous melamine-formaldehyde condensates. The addition of sugar is said to save some of the caprolactam which is more expensive than sugar in the production process, however the addition of a large amount of sugar has been found to turn the resins fairly yellow and sugar is inferior to caprolactam in some respects. A specific combination of caprolactam, sucrose or alpha-methyl glucoside and a diol is described to result in an improved aqueous impregnating MF resin solution.

[0008] However, the presence of a high amount of formaldehyde and melamine in MF resins has the risk of undesired free formaldehyde and free melamine contents.

[0009] Some attempts to reduce free formaldehyde emissions from MF resins have been described. Some documents describe the modification of MF resins, the use of formaldehyde scavengers or the use of processing steps for removing excess of formaldehyde after curing of the resins. For example, Chinese patent application published as CN 103554404 describes a low-melamine formaldehyde resin of melamine with low content of free formaldehyde prepared by reducing the mole ratio of formaldehyde to melamine and using a formaldehyde absorbent, prepared by reducing the mole ratio of formaldehyde to melamine, wherein the content of free formaldehyde is less than or equal to 0.13%. The formaldehyde absorbent is described to be any one of urea, caprolactam, H2O2 or a mixture of two or more. Chinese patent application published as CN 103626947 describes a preparation method for a melamine formaldehyde adhesive comprising caprolactam and diethylene glycol, prepared using a specific feeding sequence in the following order: formaldehyde, diethylene glycol, water, melamine and caprolactam. The prepared melamine formaldehyde adhesive is described to have a low content of free formaldehyde and is highly environmentally friendly.

[0010] However, attempts to reduce free formaldehyde content generally result in a detriment on some desirable properties of resin such as stability, reactivity, solids content, and viscosity of the formulation prior to curing, or of the properties of the cured resin in their final application such as chemical and mechanical resistance.

[0011] To obey to quality, safety and environmental requirements the industry has become more and more demanding, and there is a need in finding MF resins which, whilst maintaining their desirable properties, have reduced formaldehyde and / or melamine emissions. Also, there is a push for reducing the content of ingredients of fossil origin in the resins used and increasing the amount components of biological origin, to make them more environmentally friendly.

[0012] SUMMARY

[0013] It has now been found that an MF resin formulation responding to the demanding needs of the industry may be achieved by including a nitrogen-containing aminoalkanoic acid having at least one nitrogen on the side chain. Accordingly, the instant disclosure relates to a melamine formaldehyde (MF) resin formulation comprising a condensate of formaldehyde, melamine and a biocomponent comprising a nitrogen-containing aminoalkanoic acid having at least one nitrogen on the side chain. The instant disclosure further relates to a kit comprising said MF formulation and a condensing agent, to a method for preparing said MF resin formulation, to an impregnated cellulosic material comprising said MF resin formulation, to a cellulosic laminate comprising the same, and to methods for preparing said impregnated cellulosic material and said cellulosic laminate.

[0014] Nitrogen-containing aminoalkanoic acids are understood herein as aminoalkanoic acids having at least one nitrogen on their side chain, e.g., having a nitrogen-containing substituent on the alkanoic side chain. They are biological components and their presence in an MF resin formulation as described herein contributes to increasing the content of biocomponents in MF resins making them more environmentally friendly. Additionally, it has been found that the final properties of products comprising cured MF resins as described herein are not detrimentally affected by the presence of a nitrogen-containing aminoalkanoic acid, to the contrary, a biocomponent as described herein has been found to also contribute to provide MF resin formulations and products comprising the same with advantageous properties. For instance, the presence of nitrogen-containing aminoalkanoic acids having at least one nitrogen on the side chain have been also found to provide the formulations with desirable viscosity and stability properties and to contribute to reducing the free formaldehyde and / or free melamine content of MF resin formulations.

[0015] These and other advantages of MF formulations, cellulosic materials, cellulosic laminates and methods disclosed herein will be described in further detail below.

[0016] DETAILED DESCRIPTION

[0017] As indicated above, the instant disclosure relates to a melamine formaldehyde (MF) resin formulation comprising a condensate of formaldehyde, melamine and a biocomponent comprising a nitrogen-containing aminoalkanoic acid having at least one nitrogen on the side chain.

[0018] A condensate is understood herein by its usual meaning in the art of polymer chemistry, i.e., the product resulting of the condensation of monomers by elimination of small molecules such as water. MF resins as described herein comprise a condensate of formaldehyde, melamine and a biocomponent which is the result of the condensation of the monomers formaldehyde, melamine and a biocomponent comprising a nitrogen-containing aminoalkanoic acid having at least one nitrogen on the side chain.

[0019] A condensate as used herein is understood to comprise a condensate of formaldehyde, melamine and a biocomponent, prior to, during or after curing. As a person skilled in the art knows, MF resins are obtained after allowing the monomers to react, as will be discussed in more detail for the method of preparation, to form a condensate, that may also be referred to as pre-polymer, and are cured for their final application using heat and pressure, whereby the condensate is crosslinked, forming the cured MF resin. Accordingly, a condensate of formaldehyde, melamine and a biocomponent, as used herein may be a condensate in any of these stages, prior to, during or after curing.

[0020] An MF resin formulation as described herein in addition to comprising the formaldehyde, melamine and biocomponent condensate may additionally comprise formaldehyde, melamine and biocomponent which have not (yet) reacted to form a condensate. However, the amount of free formaldehyde, free melamine and free biocomponent is generally low, and as described in more detail below.

[0021] As indicated above a biocomponent of MF resin formulations as described herein comprises a nitrogen-containing aminoalkanoic acid having at least one nitrogen on the side chain. The biocomponent may comprise one or more different nitrogen-containing aminoalkanoic acids having at least one nitrogen on the side chain or may consist of such a nitrogen-containing aminoalkanoic acid or such a combination of nitrogen-containing aminoalkanoic acids.

[0022] Without being bound to any theory, the nitrogen-containing aminoalkanoic acid is thought to form an integral part of the condensate. Furthermore, nitrogen-containing aminoalkanoic acids having at least one nitrogen on the side chain have been found to advantageously contribute to the reduction of the amount of free formaldehyde present in the MF resin formulation and products obtained thereof. Without being bound to any theory, the side chain of the nitrogen-containing aminoalkanoic acid containing the at least one nitrogen on the side chain may react with free formaldehyde. This may provide the resin with an internal formaldehyde scavenger without having compatibility issues with the melamine and formaldehyde components of the resin.

[0023] Furthermore, it has been unexpectedly found that the use of a biocomponent comprising a nitrogen-containing aminoalkanoic acid having at least one nitrogen on the side chain advantageously increases the viscosity, stability, and latency of the MF resin formulation, as described in more detail below.

[0024] Additionally, the presence of a biocomponent comprising a nitrogen-containing aminoalkanoic acid having at least one nitrogen on the side chain has been found to provide the MF resin with the advantageous properties described above without adversely affecting other desirable properties of the resin, such as transparency, penetration capacity, reactivity, and curing of the MF resin, as will also be illustrated in more detail below.

[0025] Nitrogen-containing aminoalkanoic acids used herein may preferably comprise one nitrogen, two nitrogens or three nitrogens on the side chain.

[0026] The least one nitrogen on the side chain of nitrogen-containing aminoalkanoic acids suitable for MF resin formulations as described herein may be present in a nitrogen containing group on the side chain, e.g., a substituent on the alkanoic side chain of the aminoalkanoic acid, such as, e.g., a guanidino-substituent, an amino-substituent, an imidazole-substituent. Nitrogen-containing aminoalkanoic acids are chiral molecules that have a chiral carbon. Naturally occurring nitrogen-containing aminoalkanoic acids are typically (S) enantiomers but in methods and formulations as described (R) nitrogencontaining aminoalkanoic acids or mixtures of (S) and (R) enantiomers may be used. Nonetheless, it may be preferred to use (S) nitrogen-containing aminoalkanoic acids. In particular, a nitrogen containing aminoalkanoic acid may be selected from a 2-amino-5- guanidinopentanoic acid, such as (S)-2-amino-5-guanidinopentanoic acid; a 2,6- diaminohexanoic acid, such as (2S)-2,6-diaminohexanoic acid; a 2-amino-4-

[0027] (diaminomethylideneamino)butanoic acid, such as (2S)-2-amino-4-

[0028] (diaminomethylideneamino)butanoic acid; a 2-amino-6-

[0029] (diaminomethylideneamino)hexanoic acid, such as (2S)-2-amino-6-

[0030] (diaminomethylideneamino)hexanoic acid; a 2-amino-5-

[0031] [carbamimidoyl(hydroxy)amino]pentanoic acid, such as (2S)-2-amino-5-

[0032] [carbamimidoyl(hydroxy)amino]pentanoic acid; a 2,5-diaminopentanoic acid, such as (2S)- 2,5-diaminopentanoic acid; a 3,7-diaminoheptanoic acid, such as (3S)-3,7- diaminoheptanoic acid, and a 2-amino-3-(1 H-imidazol-5-yl)propanoic acid such as (2S)-2- amino-3-(1 H-imidazol-5-yl)propanoic acid. In several particular embodiments, such nitrogen-containing aminoalkanoic acids may be selected from a 2-amino-5- guanidinopentanoic acid, a 2,5-diaminopentanoic acid, a 2-amino-4- (diaminomethylideneamino)butanoic acid, a 2,6-diaminohexanoic acid, and a 2-amino-3- (1 H-imidazol-5-yl)propanoic acid, and more in particular may be selected from a 2-amino- 5-guanidinopentanoic acid, a 2-amino-3-(1 H-imidazol-5-yl)propanoic acid, and a 2,6- diaminohexanoic acid, and yet more in particular may be a 2-amino-5-guanidinopentanoic acid, such as (S)-2-amino-5-guanidinopentanoic acid. A 2-amino-5-guanidinopentanoic acid, a 2-amino-3-(1 H-imidazol-5-yl)propanoic acid, and a 2,6-diaminohexanoic acid have also been advantageously found to provide MF resin formulations which are transparent even after being subjected to curing. Thereby, such formulations may be useful in a wide range of applications including those where the colour and transparency of the resin may be of importance.

[0033] Melamine and formaldehyde are commercially available and may be used in a form known in the art, as also described in more detail below.

[0034] MF resin formulations as described herein may comprise components other than formaldehyde, melamine and biocomponent. For instance, in addition to a suitable solvent (e.g., water), MF resin formulations as described herein may comprise components known to impart desirable properties may be suitably used as described in more detail below.

[0035] In an MF resin formulation as described herein formaldehyde and melamine may be used at a specific molar ratio of formaldehyde to melamine, also referred to herein as F:M molar ratio, or simply as molar ratio. The molar ratio may be determined from the weight amount of formaldehyde and melamine used in the preparation of the MF resin formulation. As a mode of example, an MF resin formulation as described herein may have a molar ratio of formaldehyde to melamine from 1.2:1 to 4.1 :1 , in particular from 1.3:1 to 3.9:1 , and more in particular from 1.4:1 to 3.7:1. In several particular embodiments, an MF resin formulation as described herein may have a molar ratio of formaldehyde to melamine from 1.2:1 to 2.0:1 in particular from 1.3:1 to 1.8:1 , and more in particular from 1.4:1 to 1.6:1. Such molar ratios may be preferred as they have been found to further contribute to providing MF resin formulations with a particularly low content of free formaldehyde.

[0036] In other particular embodiments, an MF resin formulation as described herein may have a molar ratio of formaldehyde to melamine from 2.4:1 to 4.1 :1 , in particular from 2.8:1 to 3.9:1 , and more in particular from 3.0:1 to 3.7:1. Such molar ratios may be preferred as they have been found to further contribute to providing MF resin formulations with a particularly low content of free melamine.

[0037] The composition of an MF resin formulation as described herein may be characterised by the reactive matter content in wt.% with respect to the total weight of the MF resin formulation. The reactive matter being the sum of the weight amount of formaldehyde and melamine, present in the formulation. The weight amount of formaldehyde and melamine present in the formulation being with respect to the corresponding monomers (prior to be condensed).

[0038] An MF resin formulation as described herein may also be characterised by the biocomponent content in wt.%, defined by the weight amount of biocomponent monomer (prior to be condensed) with respect to the content of reactive matter as described above.

[0039] In several embodiments an MF resin formulation as described herein may comprise from 26 to 50 wt.%, in particular from 30 to 47 wt.%, and more in particular from 33 to 43 wt.% of reactive matter, as defined above.

[0040] In several particular embodiments, an MF resin formulation as described herein may comprise from 30 to 50 wt.%, in particular from 33 to 47 wt.%, and yet more in particular from 37 to 43 wt.% of reactive matter. Such resins may be preferred as they have been found to further contribute to providing MF resin formulations with a low content of free formaldehyde.

[0041] In other particular embodiments, an MF resin formulation as described herein may comprise from 26 to 44 wt.%, in particular from 30 to 40 wt.% and more in particular from 33 to 37 wt.% of reactive matter. Such resins may be preferred as they have been found to further contribute to providing MF resin formulations with a low content of free melamine.

[0042] In several embodiments an MF resin formulation as described herein may comprise from 2 to 30 wt.%, in particular from 4 to 26 wt.% of biocomponent with respect to the content of reactive matter in the MF resin formulation. Where the biocomponent consists of one or more nitrogen-containing aminoalkanoic acids having at least one nitrogen on the side chain, the amount of biocomponent corresponds to the amount of such nitrogencontaining aminoalkanoic acids. Such biocomponent weight amounts have been found to contribute to providing the advantageous effects of the biocomponent without significantly increasing production costs.

[0043] Specific combinations of molar ratio and reactive matter may be used to adjust certain properties of the resin. For instance, in several embodiments an MF resin formulation as described herein may comprise from 30 to 50 wt.%, in particular from 33 to 47 wt.%, and yet more in particular from 37 to 43 wt.% of reactive matter in combination with a F:M molar ratio from 1.2:1 to 2.0:1 in particular from 1.3:1 to 1.8:1 and more in particular from 1.4:1 to 1.6:1. Such combinations may be particularly preferred as they have been found to further contribute to providing MF resin formulations with a particularly low content of free formaldehyde. In several alternative embodiments an MF resin formulation as described herein may comprise from 26 to 44 wt.%, in particular from 30 to 40 wt.% and more in particular from 33 to 37 wt.% of reactive matter in combination with a F:M molar ratio from 2.4:1 to 4.1 :1 in particular from 2.8:1 to 3.9:1 and yet more in particular from 3.0:1 to 3.7:1 . Such combinations may be particularly preferred as they have been found to further contribute to providing MF resin formulations with a particularly low content of free melamine.

[0044] MF resin formulations as described herein may be in liquid form, e.g., may comprise a solvent. The components of the MF resin formulation may be dissolved and / or in dispersion in the solvent and MF resin formulations may be in the form of a dispersion or a solution, typically in the form of a dispersion. MF resin formulations may also be in solid form, e.g., after an MF formulation in liquid form has been applied and the solvent allowed to evaporate. MF resin formulations as described herein may also refer to the MF resin after it has been allowed to cure.

[0045] An MF resin formulation in liquid form may typically be an aqueous MF resin formulation. For instance, an MF resin formulation as described herein may comprise from 30 to 60 wt.%, in particular from 43 to 53 wt.% of water.

[0046] An MF resin formulation as described herein, e.g., in liquid form, may typically have a solids content from 40 to 70 wt.%, in particular a solids content from 50 to 60 wt.%, with respect to the total weight of MF resin formulation. The solids content of the formulation may be determined by means known in the art, e.g., by weighting the MF resin formulation containing a solvent, evaporating the solvent and weighting the residual amount of solids after solvent evaporation. As a mode of example, the average of three measurements may be taken. The measurements may be performed using, e.g., three aluminium dishes (e.g., of 40-50 mm diameter and of 10-20 mm height) dried in an air circulating oven for a minimum of 15 minutes at, e.g., 105 ± 1 °C, and cooled in a desiccator with silica gel and weighed (fared). A sample of a liquid MF resin formulation comprising a solvent, e.g., water (e.g., 2 g) may be weighted and added to each dish and placed in the air circulating oven for, e.g., two hours at 105 ± 1 °C. Then, the dishes may be cooled in a desiccator with silica gel and weighed. The solid content may be calculated for each sample as follows: solid content (%) = A x 100 / B, where A is the dried resin weight (g) and B is the weight of the sample (g) of the liquid MF resin formulation comprising a solvent prior to drying.

[0047] As indicated above, MF resin formulations as described herein may comprise components other than formaldehyde, melamine and biocomponent. In addition to a suitable solvent (e.g., water) MF resin formulations as described herein may comprise components known to impart desirable properties may be suitably used. For instance, MF resin formulations as described herein may comprise modifiers, which may be added for different purposes: increasing resin stability, improving impregnation properties (penetration), improving flow properties of the resin, e.g., plasticizing agents, flow promoters, stabilizers, wetting agents (e.g., based on ethoxylated fatty acids) and release agents (e.g., based on oleic acid).

[0048] In several embodiments, MF resin formulations as described herein may comprise an additional component selected from caprolactam; guanamines such as benzoguanamine, and acetoguanamine; polyols, such as diethylene glycol, glycerol and sugars (e.g., sorbitol, sucrose and / or glucose); amides such as dicyandiamide; and carbamide. In particular, additional components may be selected from caprolactam, benzoguanamine, carbamide and a polyol which may be preferably selected from diethylene glycol and glycerol. Caprolactam may advantageously act as plasticizing agent and stabilizer. Furthermore, may further contribute to reducing the content of free formaldehyde in the MF resin formulation. Benzoguanamine may advantageously increase resin stability and hydrophobicity of the MF resin. Carbamide may advantageously contribute to decreasing the content of free formaldehyde of the MF resin formulation and may be preferred due to its low cost. A polyol, such as diethylene glycol, glycerol, and / or a sugar (such as sorbitol, sucrose and / or glucose) may advantageously act as a plasticizing agent and may be preferred due to their low cost.

[0049] It may be preferred for MF resin formulations as described herein to comprise caprolactam and optionally comprise benzoguanamine, carbamide and / or a polyol selected from ethylene glycol, glycerol, and / or sugars such as sorbitol, sucrose and / or glucose.

[0050] In several embodiments, MF resin formulations as described herein may further comprise caprolactam, in particular from 0.5 to 10 wt.%, more in particular from 1 to 8 wt.% of caprolactam with respect to the total weight of MF resin formulation. Such amounts have been found to provide a good balance between the advantageous effects and the costs associated to the introduction of significant amounts of caprolactam. In several particular embodiments, MF resin formulations as described herein may comprise from 0.5 to 5 wt.%, in particular from 0.75 to 2.5 wt.% of caprolactam. In several alternative embodiments they may comprise from 6 to 10 wt.% in particular from 7 to 9 wt.% of caprolactam.

[0051] In several particular embodiments, MF resin formulations as described herein may optionally comprise benzoguanamine, carbamide and / or a polyol selected from diethylene glycol, glycerol, and / or a sugar such as sucrose or glucose. However, in some embodiments MF resin formulations as described herein do not comprise benzoguanamine, carbamide and / or polyol, and in some particular embodiments they neither comprise benzoguanamine nor carbamide nor polyol. For instance, it may be preferred for some low free formaldehyde resins not to comprise benzoguanamine and polyol. Accordingly, MF formulations as described herein may comprise 0 to 8 wt.% of benzoguanamine, 0 to 10 wt.% of carbamide and / or 0 to 5 wt.% of polyol with respect to the total weight of MF resin formulation. If benzoguanamine is present an MF resin formulation may typically comprise from 5 wt.% to 8 wt.% of benzoguanamine. If carbamide is present an MF resin formulation may typically comprise from 1 wt.% to 8 wt.% of carbamide. If a polyol is present an MF resin formulation may typically comprise from 2 to 5 wt.% of polyol.

[0052] MF resin formulations as described herein may further comprise a base. A base may be useful to provide alkaline conditions during methylolation and condensation of the resin and to modulate the pH of aqueous MF resin formulations. The amount of base present in the formulation may be such to adjust the pH of the MF resin formulation to a specific pH, e.g., as indicated below.

[0053] A base may be selected from a hydroxide, e.g., sodium hydroxide, and a carbonate, e.g., sodium carbonate.

[0054] An MF resin formulation as described herein may particularly have a pH from 7.25 to 11.0, in particular from 7.5 to 10.5 and more in particular from 7.75 to 10.0 and yet more in particular from 8 to 9.5. The pH may be measured by methods known in the art, e.g., using a pH-meter at a temperature of 25 °C.

[0055] MF resin formulations as described herein may further comprise a curing agent. A curing agent, e.g., a hardener, and may typically be added to an MF resin formulation just prior to its application, e.g., prior to impregnation of a cellulosic material as described in detail below. A curing agent may be present in an MF resin formulation as described herein in order to speed up the curing of MF resin formulation. A suitable curing agent may be selected from, e.g., ammonium sulphate, a mixture of sulfamic acid and an ethanolamine (such as mono-, di- and / or triethanolamine) and / or a mixture of para-toluene sulphonic acid and an ethanolamine (such as mono-, di- and / or triethanolamine). MF resin formulations comprising the curing agent may be referred to as activated MF resin formulations. When MF formulations comprise a curing agent, the curing agent may be present in an amount from 0.15 to 2.0 wt.% based on the solids content amount of the resin formulation. In particular; the hardener may be present in an amount from 0.25 to 1 .5 wt.%. Such amounts achieve the desired reactivity without compromising other properties of the formulation and without increasing the costs of the formulation unnecessarily.

[0056] The curing agent may be included in the MF resin formulation, e.g., prior to using the MF resin formulation, but may also be included as part of a kit comprising a resin formulation as described herein and a curing agent, wherein, e.g., the resin formulation and the curing agent are included in the kit separately. Accordingly, the present description also relates to kit comprising a resin formulation as described herein and a curing agent.

[0057] An MF resin formulation as described herein may comprise components other than those specifically mentioned herein but may typically consist essentially of components as described herein.

[0058] In several particular embodiments an MF resin formulation as described herein may comprise: from 26 to 50 wt.% of reactive matter, in particular from 30 to 47 wt.%, and more in particular from 33 to 43 wt.%; a F:M molar ratio from 1.2:1 to 4.1 :1 , in particular from 1.3:1 to 3.9:1 and more in particular from 1.4:1 to 3.7:1 ; from 2 to 30 wt.% of biocomponent comprising a nitrogen-containing aminoalkanoic acid having at least one nitrogen on the side chain with respect to the total weight of reactive matter present in the MF formulation, in particular from 4 to 26 wt.%; from 0.5 to 10 wt.% of caprolactam, in particular from 1 to 8 wt.%; from 0 to 8 wt. % of benzoguanamine; from 0 to 10 wt.% of carbamide; from 0 to 5 wt.% of polyol; and from 30 to 60 wt.% of water, in particular 43 to 53 wt.%; unless specified otherwise, the wt.% being based on the total weight of the resin formulation.

[0059] In several further particular embodiments an MF resin formulation as described herein may comprise: from 30 to 50 wt.% of reactive matter, in particular from 33 to 47 wt.%, and more in particular from 37 to 43 wt.%; a F:M molar ratio from 1.2:1 to 2.0:1 , in particular from 1.3:1 to 1.8:1 and more in particular from 1.4:1 to 1.6:1 ; from 2 to 30 wt.% of biocomponent comprising a nitrogen-containing aminoalkanoic acid having at least one nitrogen on the side chain with respect to total weight of reactive matter present in the MF formulation, in particular from 4 to 26 wt.%; from 6 to 10 wt.% of caprolactam, in particular from 7 to 9 wt.%;

[0060] 0 wt.% of benzoguanamine; from 1 to 8 wt.% of carbamide;

[0061] 0 wt.% of polyol; and from 43 to 53 wt.% of water. unless specified otherwise, the wt.% being based on the total weight of the resin formulation.

[0062] Such formulations have been to contribute to advantageously reduce free formaldehyde contents.

[0063] In several alternative further particular embodiments an MF resin formulation as described herein may comprise: from 26 to 44 wt.% of reactive matter, in particular from 30 to 40 wt.%, and more in particular from 33 to 37 wt.%; a F:M molar ratio from 2.4:1 to 4.1 :1 , in particular from 2.8:1 to 3.9:1 and more in particular from 3.0:1 to 3.7:1 ; from 2 to 30 wt.% of biocomponent comprising a nitrogen-containing aminoalkanoic acid having at least one nitrogen on the side chain, with respect to the reactive matter of the MF formulation in particular from 4 to 26 wt.%; from 0.5 to 5 wt.% of caprolactam, in particular from 0.75 to 2.5 wt.%; from 5 to 8 wt.% of benzoguanamine; from 0 to 8 wt.% of carbamide; from 2 to 5 wt.% of polyol; and from 43 to 53 wt.% of water; unless specified otherwise, the wt.% being based on the total weight of the resin formulation.

[0064] Such formulations have been selected to contribute to advantageously reduce free melamine contents.

[0065] As indicated above, MF resin formulations as described herein have several advantages, and are particularly suited for their application to cellulosic materials, such as paper and wood, e.g., to obtain laminated materials with a mechanically and chemically resistant surface. Some important parameters of MF resin formulations will be discussed below including free formaldehyde and free melamine contents, viscosity, stability, reactivity, water tolerance, solids content and turbidity time.

[0066] MF resin formulations as described herein may have a relatively low free formaldehyde and / or free melamine contents. In several embodiments the free formaldehyde and / or free melamine contents may be particularly low.

[0067] For instance, an MF resin formulation as described herein, e.g., a liquid MF resin formulation such as an aqueous MF resin formulation, may have a free formaldehyde content of less than 0.5 wt.%, in particular less than 0.2 wt.% and more in particular less than 0.1 wt.% with respect to the total weight of MF resin formulation. Such, low percentages of free formaldehyde advantageously increase the safety of MF resin formulations as described herein. Furthermore, MF resins formulations with low free formaldehyde contents also contribute to provide final products, e.g., impregnated cellulosic materials comprising MF resin formulations or cellulosic laminates as described herein such as melamine wooden boards or High-Pressure Laminates (HPLs), with also low free formaldehyde contents. Without being bound to any theory the presence of a biocomponent comprising a nitrogen-containing aminoalkanoic acid having at least one nitrogen on the side chain may contribute to achieving formulations with such low amount of free formaldehyde.

[0068] The free formaldehyde content may be determined by means known in the art, such as using nuclear magnetic resonance (NMR) measurements. The NMR spectra may be measured at 300K of temperature (26.85 °C) in a suitable spectrometer (e.g., a Bruker DRX- 500 11.7 T spectrometer) which may operate at 500 MHz and 125 MHz for1H and13C resonances, respectively). For instance, a sample of the MF resin formulation may be placed in a standard thin walled 5 mm NMR tube. A capillary may be inserted coaxially into the NMR tube containing a sample serving as an external concentration reference, containing, e.g., a 60 mM solution of TSP (sodium salt of the 3-(trimethylsilyl)-propionic-d4 acid) dissolved in D2O (deuterium grade 99.98 %). The13C NMR signal of TSP (5= 0 ppm) may be used for chemical shift reference and its intensity for absolute concentration reference. The13C NMR intensity response of the TSP signal in the capillary may be calibrated respect to the analogue13C NMR spectrum of a reference sample of formaldehyde of a known concentration of 1000 or 4000 ppm in water and measured under the same conditions. The capillary containing TSP may be replaced (after cleaning) for subsequent NMR measurements of the different samples. The D2O solvent in the capillary may be used for deuterium lock.

[0069] Additionally, or alternatively, an MF resin formulation as described herein, e.g., a liquid MF resin formulation such as an aqueous MF resin formulation, may have a free melamine content of less than 11 wt.%, in particular less than 8 wt.%, more in particular less than 5 wt.% and more in particular less than 1 wt.% with respect to the total weight of MF resin formulation. The free melamine content may be determined by means known in the art, such as using high-performance liquid chromatography (HPLC) measurements. For instance, a sample of an MF resin formulation as described herein may be dissolved in water (50% w / w). In parallel, several reference samples of melamine may also be prepared dissolved in water, at known concentrations, e.g., of between 200 and 1000 ppm. Reference and MF resin samples may be injected in a chromatograph (20 pL), using a suitable column (e.g., a C18 column such as Sunfire C18, from Waters), using an appropriate flow rate (e.g., of 0.8 mL / min) and a suitable analysis time (e.g., of 21 min). As solvent system water (phase A) and acetonitrile (phase B) may be used. Quantification may be performed using wavelength of 210 nm.

[0070] Such low percentages of free melamine advantageously increase the safety of MF resin formulations as described herein and they may also contribute to provide final products, e.g., impregnated cellulosic materials comprising MF resin formulations or cellulosic laminates such as melamine wooden boards or HPLs, with also low free melamine contents.

[0071] MF resin formulations as described herein have also been found to have a good viscosity, allowing the MF resin formulations to be directly applicable in the most common uses of MF resins and in typically used machinery therefor. The viscosity may be determined by methods known in the art. For instance, the viscosity of a sample of the MF resin formulation (e.g., of 500 g) may be determined using a viscosimeter (e.g., a rotational viscosimeter of type LV Brookfield) at a temperature of, e.g., 25 °C using a torque of, e.g., 50 % and a N° 1 spindle (such as a LV-1 (61) Brookfield spindle). In several embodiments, MF resin formulations as described herein, e.g., liquid MF resin formulations such as aqueous MF resin formulations, may have a viscosity from 0.01 to 0.12 Pa.s, in particular from 0.015 to 0.1 Pa.s and more in particular from 0.02 to 0.07 Pa.s. It has been surprisingly found that the presence of a biocomponent comprising a nitrogen-containing aminoalkanoic acid having at least one nitrogen on the side chain provides MF resin formulations that have an increased viscosity, when compared to the same formulation in absence of such biocomponent. For instance, where an MF formulation as described herein comprises from 4 to 26 wt.% of biocomponent with respect to the weight of reactive matter present in the MF resin formulation, the viscosity of the formulation may be increased by a 35 to 75 %, compared to the same formulation where the amount of biocomponent is replaced by, e.g., water.

[0072] Another important parameter of MF resin formulations is the water tolerance. The water tolerance of an MF resin formulation provides an indication of the degree of condensation of the MF resin and the molecular size of the generated condensate. The water tolerance is an incipient point at which a resin turns cloudy when water is added to it at a specific temperature (e.g., 25° C). The water tolerance may be expressed in grams of water per grams of aqueous resin composition and may calculated according to the following formula: Water Tolerance = (g water I g resin). The higher the amount of water that a resin formulation may accommodate or accept before turning cloudy the higher the water tolerance of the resin formulation. Generally speaking, the water tolerance will be lower when the molecular weight of the condensate and the degree of condensation of the MF resin is higher. The water tolerance is also used in the art during MF resin manufacturing to check the progress of condensation. For instance, a condensation reaction may be allowed to progress until a certain value of water tolerance is obtained, as also described below for the preparation of MF resin formulations. The water tolerance of an MF resin formulation may be determined by methods used in the art. For instance, a certain amount of MF resin formulation may be titrated by water until turbidity is observed. A sample of MF resin formulation (e.g., 10 grams of aqueous MF resin formulation) at a specific temperature (e.g., 25 °C), may be weighed into a container provided with stirring means (e.g., a beaker with a magnetized rod inside). Distilled water at the same temperature (e.g., 25 °C) is added to the MF resin formulation under stirring drop by drop using, e.g., a burette, until the sample becomes cloudy or precipitates. To ensure that the turbidity is persistent, after each drop, the mixture may be stirred for few seconds.

[0073] In several embodiments MF resin formulations as described herein, e.g., liquid MF resin formulations such as aqueous MF resin formulations, may have a water tolerance from 1.0 to 4.0, in particular from 1.2 to 3.0 and more in particular from 1.4 to 2.5. Such water tolerances have been found to provide MF resin formulations with good stability, whilst maintaining a desirable viscosity of the formulation and final properties of the products, e.g. cellulosic materials, comprising the same.

[0074] Another important parameter of MF resin formulations is the turbidity time. The turbidity time is directly related to reactivity of the resin and is the time that it takes for a resin to become turbid, in certain conditions such as an elevated temperature after addition of a curing agent (also referred to as hardener). The turbidity time may be determined by methods know in the art. For instance, a specific amount of an aqueous MF resin formulation (e.g., 100 g) may be mixed with a suitable amount of a curing agent (e.g., 0.5 g of p-toluenesulfonic acid and monoethanolamine (MEA)), a sample of the mixture may then be heated to a specific temperature, e.g., 100 °C or 180 °C, under stirring (e.g., 5 mL of the activated MF resin formulation, including the hardener, may be introduced in a test tube, and submerged in water at 100 °C or glycerine at 180 °C and gently stirred with a wire). The time that it takes for the resin to become completely white at the specific temperature is recorded as the turbidity time.

[0075] In several embodiments, MF resin formulations as described herein, e.g., liquid MF resin formulations such as aqueous MF resin formulations, may have a turbidity time at 180 °C of 50 to 150 seconds, in particular from 60 to 140 seconds, more in particular from 70 to 120 seconds and yet more in particular from 75 to 110 seconds and / or a turbidity time at 100 °C from 200 to 600 seconds, in particular from 240 to 500 seconds.

[0076] Turbidity times at 180 °C of MF resin formulations as described herein have been found to indicate a good curing of the resin under the typically used curing conditions (e.g., of pressure and temperature). They have also been found to be equivalent to those observed for commercial MF formulations used in similar applications. Turbidity times at 100 °C of MF resin formulations as described herein, have been found to indicate a low curing of the resin at outside of the curing conditions, e.g., at lower temperatures (e.g., from room temperature to up to 100 °C) at atmospheric pressure.

[0077] The combination of turbidity times at 180 °C, indicating a good curing under curing conditions, and at 100 °C, indicating a low curing outside curing conditions, e.g., lower pressure and temperature, indicates that MF resin formulations as described herein may display a good latency. In other words, they display good curing under the targeted curing conditions but will not start curing before reaching those conditions. This advantageously may provide MF resin formulations and substrates or impregnated cellulosic materials comprising the same, e.g., paper or wood, impregnated with the activated MF resin formulation, that are easier to handle and can be stored at a wide range of conditions without running the risk of the MF resin formulation to start curing outside of the targeted curing conditions, making MF resin formulations as described herein particularly suitable for most common applications, such as those requiring the impregnation of cellulosic materials.

[0078] MF resin formulations as described herein have also been found to have a good stability, which allows an MF resin formulation as described herein to have a good shelf life, by allowing its storage for prolonged periods of time after its preparation and prior to its activation with the addition of a curing agent. The stability of the MF resin formulation may be determined visually. An MF resin formulation is considered stable until the formulation starts becoming cloudy after being stored at room temperature, e.g., at 25 °C. The stability may be defined as the number of days I weeks that the MF resin formulation is free of cloudiness at 25 °C. In several embodiments, MF resin formulations as described herein, e.g., liquid MF resin formulations such as aqueous MF resin formulations, may have a stability of at least 2 weeks, in particular at least 3 weeks.

[0079] It has been surprisingly found that both the stability and latency of MF resin formulations may be significantly improved by the presence of a biocomponent comprising a nitrogen-containing aminoalkanoic acid having at least one nitrogen on the side chain, when compared to MF resin formulations which do not comprise such a biocomponent.

[0080] The present description further relates to a method for preparing an MF resin formulation as described herein, comprising condensing melamine and formaldehyde, e.g., via methylolation, in the presence of a biocomponent as described herein.

[0081] A method for preparing an MF resin formulation as described herein may particularly comprise: a) mixing formaldehyde and melamine, to provide a melamine and formaldehyde (MF) mixture; b) heating the MF mixture, in particular heating at a temperature from 90 to 100 °C, more in particular from 95 to 99 °C, to provide a heated MF mixture; c) cooling the MF mixture, in particular to a temperature from 20 to 87 °C, more in particular from 25 to 85 °C, to provide a cooled MF mixture; and d) adding a biocomponent comprising a nitrogen-containing aminoalkanoic acid having at least one nitrogen on the side chain to the cooled MF mixture to provide an MF formulation comprising a condensate of formaldehyde, melamine and a biocomponent comprising a nitrogen-containing aminoalkanoic acid having at least one nitrogen on the side chain.

[0082] A method as described herein may be performed in any suitable recipient, e.g., a flask or a reactor provided with mixing means, means for temperature control, and an inlet and outlet, which may be the same or different.

[0083] In a method as described herein, formaldehyde may be provided in different available forms, such as formaldehyde gas, paraformaldehyde (e.g., polymerized formaldehyde in solid form) and formalin solutions (e.g., aqueous solutions of formaldehyde which may be used at different concentrations, e.g., from 30 to 60 wt.% of formaldehyde based on the total weight of the aqueous solution of formaldehyde, in particular from 35 to 55 wt.%, more in particular from 37 to 45 wt.%). In several embodiments, formalin solutions may be preferred.

[0084] Melamine may also be provided in any available form, such as in solid form (such as commercially available melamine which may typically have a purity from 95.0 to 99.9 wt.%, in particular from 97.5 to 99.7 wt.% more in particular from 98.5 to 99.5 wt.%) or in admixture with a suitable solvent, such as water. The melamine and solvent mixture may be in the form of, e.g., a dispersion of melamine in the solvent (such as an aqueous dispersion of melamine) or in the form of a paste. It may be preferred to add melamine in solid form as to not increase the volume of solvent, such as water. If melamine is added in admixture with a solvent, the melamine and solvent mixture may comprise from 50 to 95 wt.% of melamine based on the total weight of the melamine and solvent mixture, in particular from 50 to 60 wt.%.

[0085] Formaldehyde and melamine may also be provided as a premixture of melamine and formaldehyde, such as what is known in the art as MF concentrate. Such mixtures may have a high molar ratio of formaldehyde to melamine, e.g., from 10:1 to 32:1 , in particular from 12:1 to 30:1 , and the MF concentrate may be combined with further melamine to obtain the desired formaldehyde to melamine molar ratio.

[0086] Mixing formaldehyde and melamine, to provide the melamine and formaldehyde (MF) mixture, of step a), may be performed in any suitable manner and order. For instance, melamine and formaldehyde may be added separately or jointly to a reactor in any suitable form, such as those indicated above including, e.g., adding an MF concentrate comprising both formaldehyde and melamine, and subjected to mixing. In several embodiments, mixing formaldehyde and melamine of step a) may comprise: i) providing an aqueous solution of formaldehyde ii) optionally adjusting the pH of the aqueous solution of formaldehyde to a pH from 7 to 12, in particular from 8 to 11 and more in particular from 9 to 10, and yet more in particular from 9.2 to 9.7; and iii) adding melamine to the aqueous solution of formaldehyde, in particular at ambient temperature, more in particular at a temperature from 25 to 30 °C, to provide a melamine and formaldehyde (MF) mixture.

[0087] An aqueous solution of formaldehyde of step a) may be commercially available or may be prepared by mixing formaldehyde (e.g., in any suitable form as described above) and water by methods known in the art. The concentration of the aqueous solution of formaldehyde may vary. For instance, in several embodiments an aqueous solution of formaldehyde may have a concentration from 30 to 60 wt.% of formaldehyde based on the total weight of the aqueous solution of formaldehyde, in particular from 35 to 55 wt.%, more in particular from 37 to 45 wt.%.

[0088] Adding melamine to the aqueous solution of formaldehyde to provide a melamine and formaldehyde (MF) mixture of step a) iii) may be performed by adding, e.g., melamine as such in solid form or in admixture with a solvent (as described above). Melamine may be added to the aqueous solution of formaldehyde at ambient temperature, e.g., at a temperature from 25 to 30 °C.

[0089] In several alternative embodiments, mixing formaldehyde and melamine of step a) may comprise: iv) providing a melamine and solvent mixture; v) optionally adjusting the pH of the melamine and solvent mixture to, e.g., from 10 to 13, in particular from 11 to 12; vi) adding the formaldehyde to the melamine and solvent mixture, optionally also comprising the base, to provide a melamine and formaldehyde (MF) mixture; and vii) optionally further adjusting the pH of the melamine and formaldehyde mixture to a pH from 7 to 12, in particular from 8 to 11 and more in particular from 9 to 10, and yet more in particular from 9.2 to 9.7.

[0090] In such embodiments melamine may be provided in a mixture with a solvent and formaldehyde may be added to melamine in the form of an aqueous solution.

[0091] Where melamine is added first, as in step a) iv), since the formaldehyde may have a tendency of decreasing the pH of the mixture obtained, it may be preferred to adjust the pH of the melamine and solvent mixture prior to the addition of formaldehyde with step a) v). Thereby, the MF mixture obtained after addition of formaldehyde may be in an appropriate target pH such as a pH from 7 to 12, in particular from 8 to 11 and more in particular from 9 to 10, and yet more in particular from 9.2 to 9.7. If the pH of the MF formaldehyde mixture is outside of the target pH, e.g., if step a) v) has not been performed or if step a) v) has been performed but it is desired to adjust the pH further, the pH may optionally be further adjusted with step a) vii).

[0092] Optionally adjusting the pH of step a) ii), step a) v) and / or step a) vii) to the targeted range may be performed, e.g., when the pH of the aqueous solution of formaldehyde of step a) i), the melamine and solvent mixture of step a) iv) or the MF mixture of step a) vi) is outside of the targeted pH range, such as, for instance: from 7 to 12, in particular from 8 to 11 and more in particular from 9 to 10, and yet more in particular from 9.2 to 9.7 for the aqueous solution of formaldehyde of step a) i), or the MF mixture of step a) vi); or from 10 to 13, in particular from 11 to 12 for the melamine and solvent mixture of step a) iv).

[0093] Where the pH is outside of a targeted pH range, the pH may be adjusted to the targeted pH by addition of a base or an acid and mixing. Typically, if outside of a targeted pH range, the pH may be adjusted by addition of a base. As a mode of example, the base may be selected from a hydroxide, e.g., sodium hydroxide, and a carbonate, e.g., sodium carbonate, a base may preferably a hydroxide and more preferably may be sodium hydroxide. An aqueous solution of a base, e.g., of sodium hydroxide, may be used. Such an aqueous solution may be at a concentration of, e.g., from 5 to 50 wt.% of base (e.g., sodium hydroxide) with respect to the total weight of the aqueous solution, in particular from 10 to 40 wt.%, more in particular from 20 to 30 wt.%.

[0094] The considerations described above for steps a) i), a) ii) and a) iii) also apply, mutatis mutandis, to steps a) iv), a) v), a) vi) and a) vii).

[0095] In step b), heating the MF mixture obtained in step a) may be performed by applying heat and mixing by means known in the art, in a flask or reactor provided with heating means. Heating may be performed to an elevated temperature from 90 to 100 °C, more in particular from 95 to 99 °C, to provide a heated MF mixture. The temperature of the heated mixture may be determined by known means, e.g., using a thermometer in contact with the heated mixture. Heating the MF mixture, e.g., to these temperatures, will typically start the condensation of melamine and formaldehyde. The heated MF mixture may be kept at an elevated temperature for a suitable time to allow the condensation reaction to progress, e.g., at an elevated reaction rate. In several embodiments, the heated MF mixture may be kept at an elevated temperature until a sample of the heated MF mixture displays turbidity when cooled to room temperature, e.g., 25 °C, in particular when a drop of the MF mixture displays turbidity when dropped into, e.g., a beaker comprising water at 25 °C. Such turbidity marks the start of condensation, as methylolated melamines start to precipitate in water, and when turbidity can be observed enough melamine has been methylolated to start condensation (i.e. , the formation of methylene and methylene-ether bridges).

[0096] As a mode of example, the heated MF mixture may be kept at an elevated temperature, e.g., for a period of time from 5 to 90 minutes, in particular from 10 to 60 minutes. With such reaction times, the above indicated turbidity may be typically achieved.

[0097] In step c), cooling the MF mixture to provide a cooled MF mixture may be achieved by means known in the art, e.g., by adjusting the means for temperature control and mixing the MF mixture. The MF mixture may be cooled to a temperature from 20 to 87 °C, in particular from 25 to 85 °C, to provide a cooled MF mixture. Cooling may be performed in one or more steps, e.g., one or two steps. For instance, when cooling is performed in two steps, in a first cooling step the MF mixture may be cooled to a temperature from 67 to 87 °C and in a second cooling step the MF mixture may be cooled to a temperature from 20 to 66 °C.

[0098] The temperature of the cooled mixture may be determined by known means, e.g., using a thermometer in contact with the cooled mixture. The cooled MF mixture may be kept at the cooled temperature, i.e., a lower temperature to that of step d) as defined herein, for a suitable time to allow the condensation reaction to progress, e.g., at a slower reaction rate to that taking place in the higher temperature of step b).

[0099] In several embodiments, the cooled MF mixture may be kept at the cooled temperature (e.g., from 20 to 87 °C, in particular from 25 to 85 °C) until a sample of the cooled MF mixture has a water tolerance of from 1.0 to 4.0, in particular from 1.2 to 3.0, more in particular from 1.4 to 2.5 at room temperature, e.g., at 25 °C. The water tolerance may be determined as described above for the MF resin formulations.

[0100] As a mode of example, the cooled MF mixture may be kept at a cooled temperature, e.g., for a period of time from 15 to 240 minutes, in particular from 30 to 120 minutes. With such reaction times, the above indicated water tolerance may be typically achieved. Such reaction times I water tolerances allow the condensation of melamine and formaldehyde without having the monomers fully condensed, e.g., achieving a partial condensation of melamine and formaldehyde, thereby allowing further condensation with the biocomponent comprising a nitrogen-containing aminoalkanoic acid having at least one nitrogen on the side chain, typically added subsequently.

[0101] In step d), adding a biocomponent comprising a nitrogen-containing aminoalkanoic acid having at least one nitrogen on the side chain to the cooled MF mixture may be performed by, e.g., adding the biocomponent as such, e.g., in solid form (such as commercially available nitrogen-containing aminoalkanoic acids which may typically have a purity from 95.0 to 99.9 wt.%, in particular from 97.5 to 99.7 wt.% more in particular from 98.5 to 99.5 wt.%) or a solution of the biocomponent in a solvent (e.g., an aqueous solution of the biocomponent). Preferably, the biocomponent may be added in solid form to avoid adding further solvent (e.g., water) to the formulation at the stage of addition of the biocomponent.

[0102] The biocomponent may be typically added at the cooled temperature (e.g., from 20 to 87 °C, in particular from 25 to 85 °C). The MF mixture with added biocomponent may be kept at the cooled temperature for a suitable time to allow the condensation reaction to further progress in the presence of the biocomponent, whereby the biocomponent may also condensate to form an integral part of the MF condensate, to provide an MF formulation comprising a condensate of formaldehyde, melamine and a biocomponent comprising a nitrogen-containing aminoalkanoic acid having at least one nitrogen on the side chain. In several embodiments, the MF mixture comprising the biocomponent may be kept at the cooled temperature (e.g., from 20 to 87 °C, in particular from 25 to 85 °C) until a sample of the MF mixture has a water tolerance of from 1 .0 to 4.0, in particular from 1 .2 to 3.0, more in particular from 1 .4 to 2.5, e.g., at 25 °C.

[0103] The water tolerance may be determined as described above for MF resin formulations as described herein. As a mode of example, the cooled MF mixture may be kept at a cooled temperature, e.g., for a period of time from 15 to 180 minutes, in particular from 30 to 120 minutes. With such reaction times, the above indicated water tolerance may be typically achieved. Such reaction times / water tolerances allow the condensation of the biocomponent with melamine and formaldehyde, and / or with the partially condensed melamine and formaldehyde. The condensation may be regarded as completed once such water tolerances have been achieved, thereby providing an MF formulation comprising a condensate of formaldehyde, melamine and a biocomponent comprising a nitrogencontaining aminoalkanoic acid having at least one nitrogen on the side chain.

[0104] The present description also relates to such MF resin formulations obtained or obtainable by such a method, and by methods comprising additional steps as described below.

[0105] For the preparation of MF resin formulations comprising components other than formaldehyde, melamine, biocomponent and a base, other components may be added at any stage of the method described herein. As a mode of example, if present, caprolactam may be typically added prior to heating the MF mixture in step b), e.g., to the MF mixture of step a), such as after addition of melamine of step a) iii) or after addition of formaldehyde of step a) vi). Adding caprolactam prior to heating may contribute for caprolactam to react and also to form part of the condensate thereby acting as an internal modifier, thereby providing the condensate, as such, with the advantageous properties of caprolactam, as described above. If present, a polyol (e.g., diethylene glycol, glycerol, and / or a sugar) may be typically added to the MF mixture of step a), and may be preferably added to the aqueous solution of formaldehyde of step a) i) prior to the addition of melamine of step a) iii). However, it may also be added in any other stage.

[0106] If present, benzoguanamine may be typically added to the MF mixture of step a), e.g., after addition of melamine of step a) ii). In several embodiments benzoguanamine may be added prior to heating of step b). In several alternative embodiments benzoguanamine may be added after the heating of step b), e.g., to the heated MF mixture, or even after cooling of step c), e.g., to the cooled mixture. If caprolactam is also present, benzoguanamine may be added after or prior to caprolactam. It may be preferred to add benzoguanamine to the heated MF mixture already comprising caprolactam and prior to the addition of a biocomponent comprising a nitrogen-containing aminoalkanoic acid.

[0107] If present, carbamide may be typically added to the MF mixture of step d) and may be preferably added to the aqueous solution of formaldehyde of step d) after the addition of the biocomponent. However, it may also be added at any other stage.

[0108] Once the condensation has been completed to provide the condensate of formaldehyde, melamine and a biocomponent comprising a nitrogen-containing aminoalkanoic acid having at least one nitrogen on the side chain as described above, the MF formulation comprising the condensate may be allowed to cool and may be removed from the reactor.

[0109] Other modifiers such as wetting agents (e.g., based on ethoxylated fatty acids) and / or release agents (e.g., based on oleic acid) may be added to the MF formulation comprising the condensate, e.g., prior being used in its final application, for instance, before being used for impregnation of a material such as a cellulosic material.

[0110] An MF resin formulation obtained or obtainable by such a method may be stored for subsequent use or may be further processed prior to subsequent use. For instance, an MF formulation may be stored at room temperature, e.g., at 25 °C. For instance, an MF resin formulation as obtained or obtainable by such a method may also be processed by concentrating the MF formulation prior to storage or prior to subsequent use. Additives may also be added to an MF resin formulation as obtained or obtainable by such a method, such as a curing agent, as described above, to provide an activated MF resin formulation. A curing agent may be typically added to the MF resin formulation directly before or shortly before its application onto, e.g., a cellulosic material. Typically, a curing agent may be added to the MF resin formulation, e.g., from 0.25 to 60 minutes before, in particular from 0.5 to 45 minutes before, and more in particular from 5 to 30 minutes before.

[0111] The present description further relates to an impregnated cellulosic material comprising an MF resin formulation as described herein. An impregnated cellulosic material is understood as a cellulosic material to which an MF resin formulation as described herein has been applied whereby, e.g., the cellulosic material is covered by the MF resin formulation or soaked with the MF resin formulation. A cellulosic material is understood as a material which major component is a cellulosic carbohydrate, such as cellulose and hemicellulose, e.g., comprising from 55 to 99 wt.% of cellulosic carbohydrates based on the total weight of the material, in particular from 65 to 97 wt.% and more in particular from 70 to 95 wt.%. Preferably, the cellulosic material may be paper.

[0112] MF formulations as described herein may be used as typically used in the industry. For instance, MF resin formulations as described herein may be used to impregnate a cellulosic material, preferably paper. Accordingly, in several embodiments the cellulosic material comprising the MF resin formulation may be impregnated with the MF formulation, e.g., impregnated paper. The impregnated cellulosic material (e.g., paper) may be subsequently applied to a substrate, typically a cellulosic substrate selected from wood or paper, and laminated thereto to form a cellulosic laminate comprising the MF resin formulation. Examples of cellulosic substrates may be paper, e.g., for forming high pressure laminates; or composite wood, e.g., selected from chipboard, OSB board, fibre board (such as medium-density fibre (MDF) board or high-density fibre (HDF) board), plywood or veneered board. Examples of cellulosic laminates include, e.g., melamine boards, high- pressure laminates or laminated composite wood.

[0113] An impregnated cellulosic material (e.g., impregnated paper) may comprise from 10 to 200 g / m2of MF resin formulation as described herein, based on the solids content of the MF resin formulation applied to the cellulosic material over the surface area of the impregnated cellulosic material, in particular from 15 to 120 g / m2. The amount of solids content of the MF resin formulation on the impregnated cellulosic material may be determined by the solids content of the resin or empirically by weighting a cellulosic material of a known surface area, and weighing after application of the MF resin formulation once the MF resin formulation has been allowed to dry and any solvent of the MF resin formulation has been removed.

[0114] An impregnated cellulosic material (e.g., impregnated paper) may have a resin content from 10 to 85 wt.%, based on the solids content (or dry weight) of the MF resin formulation applied to the cellulosic material over the surface area of the impregnated cellulosic material. Where the impregnated cellulosic material is an impregnated paper to be subsequently applied onto a wooden board (e.g. a particle wooden board) or a high- pressure laminate, the impregnated paper may preferably have a resin content from 25 to 75 wt.%, in particular from 30 to 65 wt.%, and more in particular from 40 to 60 wt.%.

[0115] For certain applications, the cellulosic material may be paper and MF resin formulations as described herein, e.g., once activated by addition of a hardener, may be applied to paper, to provide an MF resin impregnated paper which may be subsequently cured to provide what is known as melamine paper products. For instance, impregnated cellulosic materials of these type may be, e.g., melamine plates, cups, cutlery, and vases. In several embodiments, MF resin impregnated paper, what is also known as melamine decorative paper, may subsequently be applied to wood (e.g., a composite wood) such wooden board to provide laminated wood boards or melamine coated boards. An MF resin impregnated paper may be also applied onto to a stack of several layers of paper (e.g., kraft paper saturated with phenolic resin) to form a paper board, e.g., to provide what is also known as a High-Pressure Laminate (HPL). For instance, wooden or paper cellulosic materials of this type may be slats for laminated floors, furniture, worktops and wall panelling.

[0116] For certain applications the cellulosic material may be wood and MF resin formulations as described herein, e.g., incorporating a curing agent, may be directly applied to wood, or may be applied onto the wood as part of a melamine paper to provide the surface of the wood with desirable properties and finish. In several particular embodiments, the cellulosic material may be a composite wood. An MF resin formulation as described herein may be directly applied to wood or as part of a melamine paper described above impregnated with an MF resin formulation. If applied directly to wood an MF formulation as described herein may be typically applied to the surface of a composite wood. Additionally, or alternatively, it may be used to form the composite wood by applying the MF resin formulation to the veneers or the pieces of wood conforming the composite wood.

[0117] Such applications are known in the art and will not be elucidated here in further detail.

[0118] Impregnated cellulosic materials comprising an MF formulation as described herein, in addition to having the advantageous properties of MF formulations as described above, have also been found to display good properties making them particularly suitable for their final applications. For instance, an impregnated cellulosic material comprising an MF formulation as described herein, may typically retain its colour as MF formulations as described herein may advantageously be transparent. Also, the use of MF formulations as described herein may reduce defects in the final cellulosic laminates derived from, e.g., the application of pressure during curing. Some other advantageous properties of impregnated cellulosic materials as described herein are detailed in the following paragraphs.

[0119] The advantageous properties of impregnated cellulosic materials comprising MF resin formulations as described herein (e.g., impregnated paper) also provide good properties to cellulosic substrates laminated therewith. Accordingly, the instant disclosure also relates to a cellulosic laminate comprising an impregnated cellulosic material comprising an MF resin formulation as described herein. Cellulosic laminates comprising an impregnated cellulosic material comprising an MF formulation as described herein have been found to display, in several embodiments, a good curing degree, in particular a curing degree of 3 or more, may be typically displayed by cellulosic laminates as described herein. In several embodiments, the cellulosic laminates may display a curing degree of 4. A curing degree of 5 may be regarded as overly cured, such overly cured resins may lose flexibility which may be unsuited for certain applications where certain flexibility is required, such as postforming applications. The curing degree of a cellulosic laminate such as a wooden board coated with a melamine paper (also simply referred to as melamine board), may be determined by, e.g., applying an acid product also referred to as curing liquid (e.g., a 2.5 N solution of HCI comprising a 0.1 wt.% of rhodamine B) for a certain period of time (e.g., 20 minutes) onto the surface of a sample of the cellulosic laminate (e.g., melamine board of a size of 10*10 cm) which has been stabilized, e.g., at 25 °C for 24 h, prior to application of the curing liquid. The liquid is then removed, and the board surface is cleaned with ethanol and dried with a cloth or similar. The curing degree is established by visually determining the level of damage of the surface of the cellulosic laminate, as follows:

[0120] - Curing Degree 1 : delamination of the surface, with roughness and an intense loss of gloss and colour.

[0121] - Curing Degree 2: No delamination or roughness on the surface. Changes in colour and / or gloss are clearly observable.

[0122] - Curing Degree 3: Changes in gloss and / or colour are moderate and can be observed from any angle.

[0123] - Curing Degree 4 Changes in gloss and / or colour are light and can only be observed from certain angles.

[0124] - Curing Degree 5: No changes are observed.

[0125] Degrees of curing of 1 and 2 may be considered not acceptable. A degree of curing of 3 and above may be considered acceptable, of 4 may be considered particularly good. For some applications, a degree of curing of 5 may be regarded as “over-curing”, and not acceptable, such as postforming applications which require certain flexibility of the MF resins.

[0126] Cellulosic laminates comprising an impregnated cellulosic material comprising an MF formulation as described herein have been found to display, in several embodiments, a good porosity degree, in particular a porosity degree of 2 or less, may be typically displayed by cellulosic laminates as described herein. In several embodiments, the cellulosic laminates may display a porosity degree of 1. The curing degree of a cellulosic laminate such as a wooden melamine board, may be determined by, e.g., staining with a graphite pencil a sample of the cellulosic laminate (e.g., melamine board of a size of 10*10 cm) which has been stabilized, e.g., at 25 °C for 24 h, prior to staining. The stained laminate may then be cleaned and rubbed with water and soap. After some minutes, the sample may be visually analysed. The higher the porosity of the surface of the cellulosic laminate, the more resilient the stains and the more difficult for them to be cleaned by rubbing with soap. The level of porosity is established as follows:

[0127] - Porosity Degree 1 : No stains are visible.

[0128] - Porosity Degree 2: Some isolated stains can be observed on the surface of the board.

[0129] - Porosity Degree 3: Many points and some areas of the board have stains.

[0130] Degrees of porosity of 1 and 2 may be considered acceptable for most applications. Degree 1 representing a non-porous surface, and being the most preferred, whereas degree 3 may be regarded as not being acceptable.

[0131] Cellulosic laminates comprising an impregnated cellulosic material comprising an MF formulation as described herein have been found to display, in several embodiments, a good scratching resistance, in particular a scratching resistance of at least 1 .5 N may be typically displayed by cellulosic laminates as described herein, in particular of at least 2.0 N, more in particular 2.5 N, and yet more in particular 3.0 N. The scratching resistance may be expressed in Newtons (N), representing the lowest force capable of imparting a scratch as determined, e.g., according to the European standard EN 14323:2021. Briefly, the scratching resistance of a cellulosic laminate may be determined using a standardized scratch tester, with a diamond needle. Samples of cellulosic laminate (e.g., melamine board of dimensions 10*10 cm) having been stabilized, e.g., at 25 °C for 5 days, and perfectly cleaned and being handled avoiding touching the surface with the fingers. The sample is placed on the scratch tester which rotates the diamond needle in circles over the surface of the sample board, applying a defined force (N). The measurement may typically start at 1 N, with the needle turning in 1 circle over the surface, with the diamond touching the surface of the board sample. The turning diameter of the needle may then be moved 1-2 mm to produce a second 1 N circle of contact on the surface of the board. The procedure is repeated increasing the force being applied by 0.5 N, applying two circular lines for each value of force (separated 1-2 mm) and with a separation of 3-5 mm between every different force. Procedure may be continued in this way until a minimum force of 4 N is reached. After that, the sample may be stabilized, e.g., for 24 hours at 25 °C. The sample may then be analysed visually, e.g., in a light box, to identify the minimum force for which a continuous scratching line can be observed (where at least 90% of the circular line is identified as being a scratch), looking to the surface for no more than 10 seconds. A scratching line is described as the one that has penetrated in the surface and is clearly visible, because its colour contrast with the colour in the sample. If only a difference in gloss is observed the line cannot be considered as a scratching line. The scratching resistance is represented as the lowest force in Newtons which marked a continuous scratching line in the surface of the sample. For standard applications, the European standard EN 14322:2021 establishes that 1.5 N may be regarded as the minimum acceptable resistance.

[0132] Cellulosic laminates comprising an impregnated cellulosic material comprising an MF formulation as described herein have been found to display, in several embodiments, a good steam resistance, in particular a steam resistance degree of 2 or less may be typically displayed by cellulosic laminates as described herein, in particular a steam resistance degree of 1. The degree of steam resistance may be determined, e.g., according to the European standard EN 14323:2021. Briefly, the degree of steam resistance of a cellulosic laminate, may be determined by using the high tension provoked by steam on the surface of the cellulosic laminate. In particular, a sample of a cellulosic laminate (e.g., melamine board of a size of 10*10 cm) that has been previous stabilized, e.g., at 25 °C for 24 h, may be placed just on top of an Erlenmeyer flask which contains 200 mL of boiling water, for 1 hour, with the surface being analysed being the one in direct contact with the steam. After 1 hour, the surface of the cellulosic laminate may be dried, e.g., with a cloth or a paper. After 24 hours, with the sample stabilized, e.g., at 25 °C for 24 h, the central part of the sample is visually observed, and the steam resistance degree may be determined as follows:

[0133] - Steam Resistance Degree 1 : no changes are observed.

[0134] - Steam Resistance Degree 2: changes in gloss and / or colour are light and can only be observed from certain angles.

[0135] - Steam Resistance Degree 3: changes in gloss and / or colour are moderate and can be observed from any angle.

[0136] - Steam Resistance Degree 4: no delamination or blisters on the surface. Changes in colour and / or gloss are clearly observable.

[0137] - Steam Resistance Degree 5: delamination or blisters on the surface.

[0138] Steam resistance degrees of 2 or below may be regarded as acceptable, and of 1 may be regarded as the best possible result.

[0139] Cellulosic laminates comprising an impregnated cellulosic material comprising an MF formulation as described herein have been found to display, in several embodiments, a good cracking resistance, in particular a cracking resistance degree 3 or more may be typically displayed by cellulosic laminates as described herein, in particular a cracking resistance degree of 4 or more, and more in particular of 5. The degree of cracking resistance may be determined, e.g., according to the European standard EN 14323:2021. Briefly, the resistance to cracking of a cellulosic laminate may be determined when dry heat is applied on its surface. For instance, a sample of a cellulosic laminate (e.g., melamine board of a size of 25*25 cm with the edges chamfered in order to avoid possible cracks being formed from the edges) may be introduced in a forced ventilation oven, at a temperature of, e.g., 70 ± 2 °C during 24 h. Subsequently, the sample may be cooled down and stabilized in a controlled atmosphere (e.g., at 23 °C and 50% relative humidity during an additional 24 h period). Once stabilized, samples are visually inspected (with a 2x magnifying glass) and the degree of cracking resistance is determined as follows:

[0140] - Cracking Resistance Degree 1 : visible cracks over all the surface of the melamine board sample.

[0141] - Cracking Resistance Degree 2: one or two small cracks (<25mm) visible at 400 mm.

[0142] - Cracking Resistance Degree 3: hair cracks distributed throughout the surface.

[0143] - Cracking Resistance Degree 4: isolated hair cacks on the surface.

[0144] - Cracking Resistance Degree 5: no cracks can be observed.

[0145] Depending on the final application a cracking resistance degree of 3 may be acceptable as established by the European standard EN 14322:2021 defining parameters of wooden boards, however higher cracking resistance degrees of 4 and in particular of 5 may be preferred.

[0146] The present description further relates to a method for preparing a cellulosic laminate: impregnating a cellulosic material with an MF resin formulation as described herein and partially curing the impregnated cellulosic material by applying heat to the impregnated cellulosic material. The preparation of the cellulosic laminate may further comprise applying the impregnated cellulosic material onto a cellulosic substrate prior to applying pressure and heat, achieving the complete curing of the MF resin formulation.

[0147] An MF resin formulation used for preparing an impregnated cellulosic material in a method as described herein may typically be an activated MF resin formulation, comprising a suitable curing agent, as described above.

[0148] A cellulosic material (e.g., sheet of paper) may be impregnated with an MF resin formulation as described herein by methods known in the art. For instance, an MF resin formulation (e.g., an aqueous MF resin formulation in the form of a solution or a dispersion) may be typically applied by roll coating using coater rollers or by immersing the cellulosic material in the formulation.

[0149] In several embodiments an MF resin formulation may be applied onto one or more surfaces of the cellulosic material (e.g., a sheet of paper or a wooden board).

[0150] Using coater rollers, both sides of a cellulosic material may be impregnated with the MF resin formulation. Rollers used may be smooth, patterned or corrugated to control the application of the resin. The gap between rollers and / or their speed may be modulated to determine the quantity of MF resin formulation applied. The process may typically include a drying step to allow any solvent of the applied MF resin formulation (e.g., water) to evaporate. The drying step may be performed by methods known in the art such as placing the impregnated cellulosic material comprising the MF resin formulation into an oven at a temperature from 50 to 200 °C, in particular from 70 to 170 °C, e.g., a hot air oven may be used which may optionally have different sections with independent temperatures.

[0151] A process for manufacturing an impregnated cellulosic material may further comprise applying an additional resin, different from an MF resin formulation as described herein, onto the cellulosic material prior to, or simultaneous to applying an MF resin formulation. In several embodiments, if an additional resin is applied, the MF resin formulation (e.g., an aqueous MF resin formulation, such as in the form of a solution or a dispersion) may also be mixed into the resin prior to the application to the cellulosic material, and the formulation and the resin are then applied simultaneously onto the cellulosic substrate. If an additional resin is applied, it may be preferred to apply the additional resin prior to applying an MF formulation as described herein.

[0152] Suitable additional resins may be selected from aminoplast resins (e.g., urea formaldehyde (UF) resin and / or melamine urea formaldehyde (MUF) resin), phenol formaldehyde resins, epoxy resins, acrylic resins, and biobased resins such as lignin resins, tannin resins or soya resins, or mixtures thereof. A specific resin may be selected depending on the application as known to a skilled person. The resin may also be applied by methods known in the art depending on the cellulosic material being prepared.

[0153] A cellulosic substrate may be selected from composite wooden materials such as particle board (e.g., chip board), fibre board, OSB board, plywood, veneered board; or paper materials, such as kraft paper. In particular a wooden material may preferably be a particle board or fibre board and may be selected from medium-density fibre (MDF) board or high- density fibre (HDF) board. Processes for manufacturing such cellulosic substrates may correspond to processes typically used in the art with the exception that an MF resin formulation as described herein may be additionally applied onto the cellulosic substrate. As a mode of example, in several embodiments, cellulosic substrates may typically be constituted by a resin which is different from an MF resin formulation as described herein, and an MF resin formulation as described herein may be applied onto the surface of the cellulosic laminate.

[0154] Curing the impregnated cellulosic material by applying pressure and heat, may be performed by methods known in the art. The specific pressure and temperature conditions may depend on the type of cellulosic laminate being prepared and the final application of the same. Pressure and heat may be applied using a suitable press provided with heating means as known in the art.

[0155] As a mode of example, curing may be performed by applying a pressure from 15 to 90 MPa, in particular from 20 to 80 MPa, more in particular from 25 to 70 MPa and applying heat to achieve temperatures from 120 to 250 °C, in particular from 140 to 220 °C. In several embodiments, the pressure may be from, e.g., 15 to 45 MPa, in particular from 25 to 40 MPa and a temperature may be from 165 to 250 °C, in particular from 180 to 220 °C. Such pressure and temperature conditions may be preferred, e.g., for wooden products such as wooden composite boards. In other several embodiments, the pressure may be from, e.g., 45 to 90 MPa, in particular from 50 to 70 MPa and a temperature may be from 120 to 170 °C, in particular from 140 to 160 °C. Such pressure and temperature conditions may be preferred, e.g., for paper products such as high-pressure laminates.

[0156] The different step conditions and product characteristics described above for the cellulosic materials also apply to the method for preparing a cellulosic material as described herein.

[0157] When an impregnated cellulosic material is a paper which is subsequently applied to a substrate, the cellulosic material and the substrate may be the same or different. For instance, the substrate may be a cellulosic substrate selected from, e.g., a wooden board, or a paper to provide a wooden laminate or a paper laminate such as High-pressure Laminates (HPLs). A method for preparing such cellulosic laminates may typically comprise:

[0158] A) activating an MF resin formulation as described herein by adding a curing agent to the MF resin formulation, e.g., as described above;

[0159] B) applying the activated MF resin formulation on to a sheet of paper to provide an impregnated paper, and typically allowing the paper to dry, e.g., as also described above;

[0160] C) applying the impregnated paper onto a cellulosic substrate, in particular a wooden board or a paper board; and

[0161] D) applying heat and pressure on the cellulosic material comprising the impregnated paper, e.g., under the conditions described above, to provide a cured cellulosic laminate.

[0162] In this text, the term “includes”, “comprises” and derivations thereof (such as “including”, “comprising”, etc.) should not be understood in an excluding sense, that is, these terms should not be interpreted as excluding the possibility that what is described and defined may include further elements, steps, etc. The terms “in particular” and “preferably” denote embodiments within broader embodiments that may be particularly suited.

[0163] On the other hand, the disclosure is obviously not limited to the specific embodiment(s) described herein, but also encompasses any variations that may be considered by any person skilled in the art (for example, as regards the choice of materials, dimensions, components, configuration, etc.), within the general scope of the invention as defined in the claims.

[0164] EXAMPLES

[0165] Preparation of MF resin formulations and their properties

[0166] Formaldehyde 40% was diluted in water at 50 °C or higher temperature and the pH of the solution obtained was adjusted to 9.3-9.5 using sodium hydroxide 25 wt.%. Where glycerol or diethylene glycol was present in the MF resin formulation it was added to the solution obtained. To the resulting mixture, melamine and caprolactam, if present, were added and allowed to react at 92-98 °C until cloudiness in water at 25 °C achieved. If present, benzoguanamine or carbamide was added after caprolactam. The reaction mixture was then cooled down to 80-85 °C and allowed to condensate until a water tolerance of 1.2- 2.5 was achieved. Subsequently, the mixture was cooled down to 45-55 °C and the nitrogen-containing aminoalkanoic acid was added and allowed to react for 30 minutes. The resulting product was then cooled down to room temperature and thoroughly characterised.

[0167] The table below shows the MF resin formulations prepared indicating the amounts of each of the components added, indicated as the weight of each component, unless otherwise indicated. The table further includes properties of the MF resins prepared, determined according to the methods detailed below.

[0168] Measurement of MF resin formulation properties:

[0169] The properties of the resin were measured as described above, using specific conditions and parameters detailed as follows:

[0170] Solid content: Three dishes (aluminium dishes of 40-50 mm diameter and of 10- 20 mm height) were dried in an air circulating oven for a minimum of 15 minutes at 105 ± 1 °C, cooled in a desiccator with silica gel and weighed (fared). A sample of each MF resin formulation (2 g) was then added to each dish and placed in the air circulating oven for two hours at 105 ± 1 °C. Then, they were cooled in a desiccator with silica gel and weighed. The solid content was calculated as follows: Solid content (%) = A x 100 / B, where A was the dried resin weight (g) and B was the weight of the aqueous resin composition sample (g).

[0171] Free formaldehyde: was measured by NMR at 300K of temperature (26.85 °C) using a Bruker DRX-500 11.7 T spectrometer operating at 500 MHz and 125 MHz for1H and13C resonances, respectively. The sample of MF resin formulation to be measured was placed in a standard thin walled 5 mm NMR tube. A capillary was inserted coaxially into the NMR tube containing a 60 mM solution of TSP (sodium salt of the 3-(trimethylsilyl)-propionic-d4 acid) dissolved in D2O (deuterium grade 99.98%) serving as an external concentration reference. The13C NMR signal of TSP (5= 0 ppm) was be used for chemical shift reference and its intensity for absolute concentration reference. The13C NMR intensity response of the TSP signal in the capillary may be calibrated respect to the analogue13C NMR spectrum of a reference sample of formaldehyde of a known concentration of 1000 or 4000 ppm in water and measured under the same conditions. The capillary containing TSP was replaced (after cleaning) for subsequent NMR measurements of the different samples. The D2O solvent in the capillary was used for deuterium lock.

[0172] Free melamine: was measured by HPLC dissolving each sample in water (50% w / w) and using reference samples of melamine in water, at known concentrations of between 200 and 1000 ppm. The samples were injected in a chromatograph (20 pL), using a Sunfire C18 column (from Waters) and a flow rate of 0.8 mL / min and an analysis time of 21 min using water (phase A) and acetonitrile (phase B) as the solvent system and performing the quantification using wavelength of 210 nm.

[0173] Viscosity: at 25 °C in a Rotational Viscosimeter Type LV Brookfield using a torque of 50 % and a spindle N° 1 . pH: at 25 °C using a standard pH-meter.

[0174] Water tolerance: 10 grams of aqueous resin composition at 25 °C were titrated in a beaker provided by a magnetic stirrer with distilled water at 25 °C added drop by drop, from a burette, until the sample became cloudy or precipitated. A few seconds are waited to ensure that the turbidity is persistent. Water tolerance expressed in grams of water per grams of aqueous resin composition, is calculated according to the following formula:

[0175] Water tolerance = (g water I g resin)

[0176] Turbidity time: 100 g of resin were mixed with 0.5 g hardener (a mixture of p- toluenesulfonic acid and monoethanolamine). 5 mL of this mixture were introduced in a test tube and submerged in glycerine at 180 °C. The mixture inside de test tube was gently stirred with a wire. Turbidity time was the time it took for the resin to become completely white.

[0177] Stability: the MF resin formulations were stored in a tank at a temperature 25 °C and humidity of 50-60%, until the apparition of cloudiness was visually observed. The resin was considered stable until said cloudiness appeared.

[0178] Preparation of cellulosic laminates and their properties:

[0179] Paper was impregnated with the MF resins of examples 1-7, by immersing the paper in a bath of the MF resin and passing it through two dosing rolls. After that, the impregnated paper was dried in an oven at 135 °C. This process was repeated twice. The resin content of the impregnated paper is detailed in the table below and is expressed in terms of wt.% based on the dry weight (i.e. , the solids content) of the resin and the total weight of the dried impregnated paper. The dried impregnated paper was pressed over a wooden particle board during 40 seconds in a press at 190 °C and 40 MPa to provide the melamine boards. Measurement of cellulosic laminates properties:

[0180] The properties of the resin were measured as described above, using specific conditions and parameters detailed as follows:

[0181] Scratching Resistance: a sample of 10*10 cm of the melamine board was used and stabilized at 25 °C, for 5 days and the scratching resistance was determined as described above.

[0182] Steam Resistance: a sample of 10*10 cm of the melamine board was used and stabilized at 25 °C, for 24 hours. The sample was placed on top of an Erlenmeyer flask containing 200 mL of boiling water, for 1 hour (the face to be analysed was in contact with the steam). After 1 hour, the surface of the board was dried with a cloth or paper and stabilized at 25 °C, for 24 hours. Steam Resistance was determined as described above.

[0183] Cracking Resistance: a sample of 25*25 cm of the melamine board was used. The sample was introduced in a forced ventilation oven, at a temperature of 70 ± 2 °C during 24 h. After that, sample was cooled down in a controlled atmosphere (23 °C and 50% relative humidity) during further 24 h. Once stabilised, samples are visually inspected (with a 2x magnifying glass) and results are represented in degrees as described above.

[0184] Curing Degree: a sample of 10*10 cm of the melamine board was used and stabilized at 25 °C, for 24 hours. Then a 2.5 N HCI solution and 0.1 wt.% rhodamine B solution was used to stablish the curing degree. The liquid mixture was applied for 20 minutes over the surface of the board.

[0185] Porosity Degree: a sample of the melamine board was stabilised at 25 °C and stained with a graphite pencil.

[0186] Colour s Transparency: The colour and transparency of the MF resin formulation on the melamine board was assessed visually.

Claims

CLAIMS1. A melamine formaldehyde (MF) resin formulation comprising a condensate of formaldehyde, melamine and a biocomponent comprising a nitrogen-containing aminoalkanoic acid having at least one nitrogen on the side chain.

2. The MF resin formulation of claim 1 , wherein the nitrogen-containing aminoalkanoic acid having at least one nitrogen on the side chain is selected from a 2- amino-5-guanidinopentanoic acid, a 2,6-diaminohexanoic acid, a 2-amino-4- (diaminomethylideneamino)butanoic acid, a 2-amino-6-(diaminomethylideneamino)- hexanoic acid, a 2-amino-5-[carbamimidoyl(hydroxy)amino]pentanoic acid, a 2,5- diaminopentanoic acid, a 3,7-diaminoheptanoic acid, and a 2-amino-3-(1 H-imidazol-5- yl)propanoic acid, in particular is selected from a 2-amino-5-guanidinopentanoic acid, a 2,5- diaminopentanoic acid, a 2-amino-4-(diaminomethylideneamino)butanoic acid, a 2,6- diaminohexanoic acid and a 2-amino-3-(1 H-imidazol-5-yl)propanoic acid, more in particular is selected from a 2-amino-5-guanidinopentanoic acid, a 2-amino-3-(1 H-imidazol-5- yl)propanoic acid and a 2,6-diaminohexanoic acid, and yet more in particular is a 2-amino- 5-guanidinopentanoic acid such as (S)-2-amino-5-guanidinopentanoic acid.

3. The MF resin formulation of claim 1 or2, having a molar ratio of formaldehyde to melamine from 1.2:1 to 4.1 :1 , in particular from 1.3:1 to 3.9:1 , and more in particular from 1.4:1 to 3.7:1.

4. The MF resin formulation of any one of claims 1 to 3, comprising from 26 to 50 wt.%, in particular from 30 to 47 wt.%, and more in particular from 33 to 43 wt.% of reactive matter with respect to the total weight of the MF resin formulation, the reactive matter being the sum of the weight amount of formaldehyde and melamine.

5. The MF resin formulation of any one of claims 1 to 4, comprising from 2 to 30 wt.%, in particular from 4 to 26 wt.% of a biocomponent comprising a nitrogen-containing aminoalkanoic acid having at least one nitrogen on the side chain, where the wt.% is defined by the weight amount of biocomponent monomer with respect to the content of reactive matter, the reactive matter being the sum of the weight amount of formaldehyde and melamine.

6. The MF resin formulation of any one of claims 1 to 5, further comprising caprolactam, in particular from 0.5 to 10 wt.%, more in particular from 1 to 8 wt.% of caprolactam with respect to the total weight of MF resin formulation.

7. The MF resin formulation of any one of claims 1 to 6, optionally comprising benzoguanamine, carbamide and / or a polyol selected from diethylene glycol, glycerol, and a sugar such as sucrose and / or glucose, in particular comprising 0 to 8 wt.% ofbenzoguanamine, 0 to 10 wt.% carbamide and / or 0 to 5 wt.% of polyol with respect to the total weight of MF resin formulation.

8. The MF resin formulation of any one of claims 1 to 7, comprising from 30 to 60 wt.%, in particular from 43 to 53 wt.% of water and / or having a solids content from 40 to 70 wt.%, in particular from 50 to 60 wt.%, with respect to the total weight of MF resin formulation.

9. The MF resin formulation of any one of claims 1 to 8 having a pH from 7.25 to 11.0, in particular from 7.5 to 10.5 and more in particular from 7.75 to 10.0 and yet more in particular from 8 to 9.5.

10. The MF resin formulation of any one of claims 1 to 9, having a free formaldehyde content of less than 0.5 wt.%, in particular less than 0.2 wt.% and more in particular less than 0.1 wt.%. and / or having a free melamine content of less than 11 wt.%, in particular less than 8 wt.%, more in particular less than 5 wt.% and more in particular less than 1 wt.% with respect to the total weight of MF resin formulation.

11. The MF resin formulation of any one of claims 1 to 10, having a viscosity from 0.01 to 0.12 Pa.s, in particular from 0.015 to 0.10 Pa.s and more in particular from 0.02 to 0.07 Pa.s.

12. The MF resin formulation of any one of claims 1 to 11 further comprising a curing agent, in particular a curing agent selected from ammonium sulphate, a mixture of sulfamic acid and an ethanolamine (such as mono-, di- and / or triethanolamine) and / or a mixture of para-toluene sulphonic acid and an ethanolamine (such as mono-, di- and / or triethanolamine), more in particular in an amount from 0.15 to 2.0 wt.% based on the solids content amount of the resin formulation, yet more in particular in an amount from 0.25 to 1.5 wt.%.

13. A kit comprising an MF resin formulation of any one of claims 1 to 11 and a curing agent, in particular a curing agent selected from ammonium sulphate, a mixture of sulfamic acid and an ethanolamine (such as mono-, di- and / or triethanolamine) and / or a mixture of para-toluene sulphonic acid and an ethanolamine (such as mono-, di- and / or triethanolamine).

14. A method for preparing an MF resin formulation of any one of claims 1 to 12 or a kit of claim 13 comprising: a) mixing formaldehyde and melamine, to provide a melamine and formaldehyde (MF) mixture; b) heating the MF mixture, in particular heating at a temperature from 90 to 100 °C, more in particular from 95 to 99 °C, to provide a heated MF mixture; c) cooling the MF mixture, in particular to a temperature from 20 to 87 °C, more in particular from 25 to 85 °C, to provide a cooled MF mixture; andd) adding a biocomponent comprising a nitrogen-containing aminoalkanoic acid having at least one nitrogen on the side chain to the cooled MF mixture to provide an MF formulation comprising a condensate of formaldehyde, melamine and a biocomponent comprising a nitrogen-containing aminoalkanoic acid having at least one nitrogen on the side chain.

15. The method according to claim 14 wherein mixing of step a) comprises: i) providing an aqueous solution of formaldehyde ii) optionally adjusting the pH of the aqueous solution of formaldehyde to a pH from 7 to 12, in particular from 8 to 11 and more in particular from 9 to 10, and yet more in particular from 9.2 to 9.7; iii) adding melamine to the aqueous solution of formaldehyde, in particular at ambient temperature, more in particular at a temperature from 25 to 30 °C, to provide a melamine and formaldehyde (MF) mixture.

16. An impregnated cellulosic material comprising an MF resin formulation of any one of claims 1 to 12, preferably the cellulosic material is paper.

17. A cellulosic laminate comprising an MF resin formulation of any one of claims 1 to 12, or an impregnated cellulosic material of claim 16.

18. A method for preparing a cellulosic laminate of claim 17 comprising: impregnating a cellulosic material with an MF resin formulation of any one of claims 1 to 12 and curing the impregnated cellulosic material by applying pressure and heat to the cellulosic material.

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