ALKYD RESIN COMPOSITIONS COMPRISING AN AROMATIC COMPOUND

Abstract

The invention relates to an alkyd resin composition comprising (A) at least one unsaturated fatty acid, (B) at least one polyol, (C) at least a catalyst, and (D) at least one aromatic compound with the following structure: R2 (\'\IRS / R3 R1 with R1 = H or CH3 or COOH; R2 = H or CH3; R3 = COOH or form together an anhydride bridge CO-O-OC.

Description

Field of the invention The present invention relates to an alkyd resin composition comprising an aromatic compound. The present invention furthermore relates to the process for making this alkyd resin composition. The present invention also relates to the use of these alkyd resin compositions. Background of the invention Alkyd resins have long been established as one of the most widely used resins in the coatings industry due to their versatile properties, which include good adhesion, gloss, durability, and flexibility. They are synthesized by the polycondensation of polyhydric alcohols (such as glycerol or pentaerythritol), polybasic acids (such as phthalic anhydride), and fatty acids derived from natural oils, providing them with both thermoplastic and thermosetting characteristics. Fatty acids can be added as such or alternatively as natural oils, as triglycerides. Alkyd resins can be classified based on their oil length, which significantly influences their final properties. Oil length is defined as the weight percentage of fatty acid building blocks (calculated as their triglycerides): - Short-oil alkyd resins (with <40% oil content) tend to dry faster and form harder films, making them suitable for industrial baking enamels and lacquers. - Medium-oil alkyd resins (with 40-60% oil content) balance durability and flexibility and are commonly used in architectural coatings. - Long-oil alkyd resins (with >60% oil content) are softer and more flexible, often used in air-drying systems such as decorative paints. In general, long oil lengths (55 % or higher) result in improved oxidative drying, good substrate adhesion, excellent flow properties, good solubility in aliphatic solvents, and low viscosity, even with low solvent content. However, these alkyds show strong yellowing. Despite their widespread use, traditional alkyd resins are not without limitations. One of the primary challenges in the use of alkyd resins formulations in coatings is curing, particularly in air-drying systems where the resin relies on oxidative cross-linking to form a solid film. This process is complex therefore is often slow leading to long drying times and potential issues such as surface tackiness or incomplete through-drying. When an alkyd-based paint is applied onto a surface, the fatty acid moieties of the alkyd resin react with oxygen from the atmosphere to form hydroperoxides which subsequently decompose to form free radicals. Reaction of these free radicals with the unsaturated carbon-carbon bonds of the fatty acid moieties causes covalent bonds to be formed between the unsaturated fatty acids chains, thus forming cross-links between polymer chains. In this way, a liquid coating composition that comprises alkyd resin hardens to form a solid cured coating. This process is also referred to as auto-oxidation or drying. Autoxidation and crosslinking of the unsaturated oil / fatty acid component can proceed unaided, but the time for drying is generally found to be unacceptably long for many practical purposes. The reactions are significantly accelerated by the presence of a metal-based drying catalyst, commonly referred to as a "drier". Whereas an alkyd coating may takes months to dry in the absence of a drying catalyst, in the presence of such a catalyst, drying can be accomplished within a few hours. In WO2016102464 a coating composition is described, comprising an alkyd-comprising resin and a drier comprising a dinuclear ligand-manganese complex comprising manganese and a 1,4,7-trisubstituted-1,4,7- triazacyclononane ligand, wherein the alkyd comprising resin is an alkyd- stabilized non-aqueous dispersion of particles of addition polymer in a non- aqueous liquid phase comprising alkyd. Summam of the invention It is an objective of the present invention to address one or more of the disadvantages faced in the prior art. It is another objective of the invention to provide novel alkyd resin formulations that introduce alternative functionalized aromatic compounds as innovative building blocks for alkyd resins formulations. Further objectives include the use of biobased aromaticcompounds as innovative building blocks for alkyd resins formulations. A particular objective is to provide an efficient and low-cost process for the production of bio-MPA based alkyd coatings. A further objective is to provide a new type of cross-linking capability. Accordingly, the present invention relates to an alkyd resin composition comprising (A) at least one unsaturated fatty acid, (B) at least one polyol, (C) at least a catalyst, and (D) at least one aromatic compound with the following structure: R2 ÔERB / R3 R1 with R1 = H or CH3 or COOH; R2 = H or CH3; R3 = COOH or form together an anhydride bridge CO-O-OC. Furthermore, the present invention relates to a process for the preparation of an alkyd resin composition, wherein (A) at least one unsaturated fatty acid, (B) at least one polyol, (C) at least a catalyst, and (D) at least one aromatic compound with the following structure: R2 ËÏRS / R3 R1 with Ri = H or CH3 or COOH; R2 = H or CH3; R3 = COOH or form together an anhydride bridge CO-O-OC are added to a reactor to form a reaction medium and the reaction medium is stirred and heated to at least 100°C. The present invention also relates to the use of at least one aromatic compound with the following structure: R2 iii-??, / R3 R1 with Ri = H or CH3 or COOH; R2 = H or CH3; R3 = COOH or form together an anhydride bridge CO-O-OC; into an alkyd resin composition comprising furthermore (A) at least one unsaturated fatty acid, (B) at least one polyol, (C) at least a catalyst. Detailed description of the invention Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Applications are more and more tested with sample amounts of biobased 3-MPA and / or 3,6DMPA and fossil based 4-MPA. The innovative alkyd resin composition of the present invention relates to a final resin composition comprising at least one aromatic compound with the following structure: R2 Ô? | / / R3 R1 with Ri = H or CH3 or COOH; R2 = H or CH3; R3 = COOH or form together an anhydride bridge CO-O-OC. These molecules are relatively new and up till now available in small amounts only. For application in alkyd resin compositions, it is needed that larger quantities can be produced, otherwise application will remain possible on small scale only. On the other hand, the aromatic compound such as for example 3-methylphthalic anhydride (3-MPA), showed surprisingly outstanding oxidative cross-linking capabilities, specially in respect to its non substituted counterpart like phthalic anhydride (PA). This leads to faster drying times, better film formation, improved film properties and reduced environmental impact, even when added in low quantities as specialty chemical. The following molecules are preferably represented above in the structure of the aromatic compound: 3-methylphthalic anhydride (3-MPA) (CAS 4792-30- 7), 3-methylphthalic acid (3-MPA) (CAS 37102-74-2), 4-methylphthalic anhydride (4-MPA) (CAS 19438-61-0), 4-methylphthalic acid (4-MPA) (CAS 4316-23-8), 3,6-dimethylphthalic acid (DMPA) (CAS 944-38-7), 3,6-dimethylphthalic anhydride (DMPA) (CAS 5463-50-3), hemimellitic acid (HIVIA) (CAS 732304-21- 1), hemimellitic anhydride (HMA), trimellitic anhydride (TMA) (CAS 552-30-7) and trimellitic acid (TMA) (CAS 528-44-9). Of these, 3-IVIPA and DMPA are biobased, while the others are fossil based molecules. Also the term bio-based MPA and / or DIVIPA or bio-MPA or bio IVIPA is sometimes used, and includes 3- methylphthalic anhydride (3-MPA), 3-methylphthalic acid (3-MPA), 3,6- dimethylphthalic acid (DMPA) and 3,6-dimethylphthalic anhydride (DMPA). The present invention was aimed to replace phthalic anhydride (PA), or functionally equivalent molecules, either fully or at least partially with substituted aromatic compounds, such as bio-based methyl phthalic anhydride (3-MPA), without requiring further changes to the formulation. However, we observed that the polyesterification of aromatic compounds with the structure as described above, including 3-MPA, during alkyd resin composition production occurs at a much slower rate compared to PA, under the same process conditions. To solve this issue, we now found that a catalyst is needed to accelerate the reaction rate in for example 3-MPA-based and DMPA-based alkyd resin synthesis. Surprisingly, we found that the catalysed reaction speed of for example 3-MPA matches the reaction speed of the traditional PA-based formulation by using the catalyst concentrations and same reaction conditions outlined in this invention. Besides replacement of phthalic anhydride, also molecules like for example fumaric acid, maleic anhydride, levopimaric acid, itaconic acid, isophtalic acid, terephthalic acid, succinic acid, furan dicarboxylic acid may be fully or at least partially replaced with the substituted aromatic compounds, such as bio-based methyl phthalic anhydride (3-MPA), without requiring further changes to the formulation. The term acid value (AV) in the context of alkyd resin composition synthesis is a measure of the amount of free acid present in the resin and is used to quantify the degree of polymerization of the components. It is a titration technique. It is defined as the amount of potassium hydroxide (KOH) in milligrams required to neutralize one gram ofthe resin sample. This value helps to determine the degree of polymerization and the extent of the reaction during the synthesis of alkyd resin compositions. It is calculated using the following empirical equation 1: AV : _leCÎqHsÏnÎÊÎSÔ'l [equation 1] The acid value (AV) obtained from Equation 1 is then used to calculate the degree of polymerization (or conversion) as a percentage (%), using equation 2: conversion =% [equation 2] with AVO being the acid value before reaction and AVt being the acid value at time t of the reaction. Generally, the reaction is considered completed when a plateau of the curve is reached and preferably when an acid value below 12 is measured corresponding to a conversion greater than 95%. Together with the acid value, another important parameter to measure is viscosity. Viscosity is correlated with the molecular weight of the polymers obtained in the alkyd synthesis reaction by the Mark-Houwink relationship defined as: [n] : K*l\ / la [equation 3] with [n] being the intrinsic viscosity of the polymer solution, M the molecular weight of the polymer chains in the solution and Kand a being the lVlarkHouwink parameter for a specific polymer solution. It might occur that for an obtained acid value that is within specifications, the viscosity value is too low. This is an indication that the stoichiometry of the reaction has resulted in chain lengths that are small in mass and therefore the global molecular weight of the obtained resin is too low. The innovative alkyd resin composition of the invention relates to a resin composition comprising (A) at least one unsaturated fatty acid, (B) at least one polyol, (C) at least a catalyst, and (D) at least one aromatic compound with the structure as described above. The polymerization of alkyd resins primarily involves an esterification reaction, where hydroxyl groups from the polyols react with carboxyl groups from the polybasic acids or fatty acids. The general mechanism is exemplified as follows, with the components and overall reactions involved in the synthesis of an alkyd resin composition. The presence of both polyols (in the below example glycerol and pentaerythritol) is not strictly required synthesis can proceed with only one polyol: C\\\SOH 9 go 0 0 0 o 0 OH o + www + .095 + ©? OH O E glycerol pentaerythritol (methyl)phthalic anhydride leo fatty acid alkyd The backbone of this alkyd resin example is based on (methyl)phthalic anhydride and glycerol, where the acid and alcohol functional groups of both can react together to form ester bonds (number 1 in the above scheme). Alkyd resin synthesis occurs in a step-growth manner. In this mechanism, small oligomers are formed in the early stages of the reaction, which subsequently react with other oligomers or monomers to form larger chains. Because glycerol is trifunctional and only two functional groups are used to create a linear polymer chain, the third alcohol group can be used to attach the fatty acid side chain to the polymeric backbone, thereby providing the resin with some flexibility but also the necessary double bonds for the final oxidative crosslinking in the applied coating (number 2 in the above scheme). Pentaerythritol is used to replace some of the glycerol and thereby resulting in a branched polymer with fatty acid side chains instead of a pure linear polymer. The purpose of this is to create larger alkyd resin molecules with more unsaturated side chains and thus more crosslinking in the final coating, while keeping a relatively low viscosity which improves the solid contents of the paint as well as its applicability with a brush, roller or spray gun. Worth mentioning is that the second acid group of the anhydride might behave differently for phthalic acid anhydride and methyl phthalic acid anhydride, as the methyl group of the latter could cause some steric hindrance around the carboxylic group and thereby a slower reaction rate of that acid group. It was found that by replacing phthalic anhydride with the aromatic compound with the structure as described above the reaction was not taking place at all or at a very slow rate. Catalysts are generally used to speed up the synthesis and to achieve desired performance characteristics in the alkyd synthesis process. To solve the problem a suitable catalystwas searched for, as the more commonly used catalyst for phthalic anhydride was not performing optimally. Various materials may be used to catalyse the reaction between anhydrides and polyols. The catalyst (C) of the present invention is preferably one out of the group of metal salts and / or inorganic acids and / or bases, organic acids and / or bases, and / or organometallic acids and / or bases. Examples of catalysts in alkyd resin formulations to facilitate the esterification process are acid catalysts, such as p-toluene-sulfonic acid (pTSA) or sulfonic acids, hydrochloric acid, or phosphoric acid, preferably used in a concentration in the range of from 0.5 up to 3.0 wt.% of the total solid matter in the formulation. Other examples of catalysts in alkyd resin formulations are metallic catalysts, like lithium and tin compounds, preferably used in very low concentrations, more preferably in the range of from 0.01 up to 1 wt.% based on the solid content of the resin. More preferably, catalyst (C) of the present invention is lithium hydroxide, butyl-stannoic acid, mono-butyl-tin oxide, di-butyl-tin oxide, hydrochloric acid, and / or p-toluene sulphonic acid. It was found that lithium hydroxide, butyl- stannoic acid, mono-butyl-tin oxide, di-butyl-tin oxide, hydrochloric acid, and / or p-toluene sulphonic acid had the best performance for the alkyd resin composition of the invention. Advantageously, the amount of catalyst is in the range of from 0.001 up to 0.8 wt%, preferably in the range of 0.005 to 0.3 wt%. Alkyd resins are commonly used as binders in paint formulations due to their excellent film-forming properties, adhesion, and durability. However, the composition and optimization of the coating formulation requires other components such as pigments and additives. When applied onto a surface the fatty acids moieties react with the oxygen from the atmosphere to form hydroperoxides which subsequentiallydecompose to form free radicals. Reaction of these free radicals with the unsaturated carbon-carbon bonds of the fatty acid moieties causes covalent bonds to be formed between the alkyd polymer chains, thus forming cross-links between polymer chains. In this way, a liquid coating composition that comprises alkyd resin hardens to form a solid cured coating. This process is also referred as auto oxidation or simply drying. Until now, the time employed for such a composition to dry, relied only on the concentration and type of oil and / or fatty acids used to prepare the resin. Autoxidation and cross linking of the unsaturated oil / fatty acid may proceed unaided, but the time for drying is generally found to be problematic in environments requiring fast turnaround times or multiple coats, where long drying intervals can lead to inefficiencies. The reactions may be significantly accelerated by adding drying catalysts, usually transition metal-based, commonly referred as driers. By switching from a lower valence state to a higher valence state these metals within the dryer catalyses auto-oxidation, forming a complex with both atmospheric oxygen and the double bonds of the unsaturated fatty acids groups within the composition. ln W02016102464 a coating composition is described comprising an alkyd comprising resin and a catalyst comprising a dinuclear ligand-manganese complex comprising manganese and a 1,4,7-trisubstituted-1,4,7- triazacyclononane ligand. The following molecules are preferred as the aromatic compound in the composition of the invention: biobased 3-methylphthalic anhydride (3-lVlPA), biobased 3-methylphthalic acid (3-lVlPA), biobased 3,6-dimethylphthalic acid (DMPA), biobased 3,6-dimethylphthalic anhydride (DMPA), fossil based 4- methylphthalic anhydride (4-MPA), fossil based 4-methylphthalic acid (4-MPA), fossil based hemimellitic acid (HMA), fossil based hemimellitic anhydride (HMA), fossil based trimellitic anhydride (TMA) and / or fossil based trimellitic acid (TMA). More preferably, the aromaticcompound is bio-based 3-MPA and / or DMPA, even more preferably bio-based 3-MPA. As it is the idea that the aromatic compound replaces at least partly phthalic anhydride, or similar molecules with similar functionality, in conventional resins, the aromatic compound is preferably present in the range of from 5 up to 50wt% relative to the total amount of solid matter of the resin, more preferably in the range of from 10 up to 40 wt%, even more preferably in the range of 10 up to 30% wt. We also surprisingly found that the aromatic compound comprises extra cross-linking functionalities. Thus besides replacing molecules with similar functionalities like phthalic anhydride, the aromaticcompound might be added as specialty chemical for the crosslinking effect. In this case the aromaticcompound is preferably present in the range of from 0.1 up to 5 wt% relative to the total amount of solid matter of the resin, more preferably in the range of from 0.5 up to 3 wt%. Preferably, the alkyd resin composition furthermore comprises phthalic anhydride (PA). lVlore preferably, the molar ratio between (i) the total amount of aromatic compound and (ii) PA is in the range of from 100:1 up to 1:100, preferably in the range of from 10:1 up to 1:10, more preferably in the range of 5:1 up to 1:5. Advantageously, the polyol (B) is a trivalent alcohol and / or a quadrivalent alcohol, more preferably trimethylolpropane, glycerol, pentaerythritol and / or (di)pentaerythritol. The polyol (B) suitably is glycerol, that is part of a natural oil, where three fatty acid molecules are attached to. It is furthermore included that the fatty acid (A) and the polyol (B) are one molecule in the form of a triglyceride ofthe natural oil. Examples that are suitable forthe present invention are soybean oil, rapeseed oil, linseed oil, camelina oil and sunflower oil. Examples of suitable fatty acids are unsaturated ones that include unsaturated conjugated or non-conjugated double bonds and aliphatic chain lengths of a number of carbon atoms between C10 C24. Fatty acids can be different combinations of fatty acids derived from natural oils such as soybean oil, linseed oil, sunflower oil, rapeseed oil, camelina oil, safflower oil, palm oil or even less common oil types such as tung oil, calendula oil, wood oil, tallow oil, (dehydrated) castor oil, fish oil, coconut oil palm kernal oil, and combinations thereof. Advantageously, the fatty acid (A) comprises fatty acids derived from natural oils, more preferably derived from soybean oil, linseed oil, sunflower oil, rapeseed oil, camelina oil, safflower oil, palm oil and / or combinations thereof, even more preferably derived from soybean oil, rapeseed oil, linseed oil, camelina oil and sunflower oil. Even more preferable fatty acids derived from sunflower oil and / or soybean oil are used, as these contain a relatively high % of desired conjugated double bonds. Also the whole oil might be used, in the form of a triglyceride instead of a fatty acid. In a further alternative embodiment the whole oil is used, next to a separately added polyol (B) and / or a separately added fatty acid (A). ln such a situation there is the possibility to set every ratio between (A) and (B) instead of the fixed ratio that a natural oil provides. Preferably the one or more alkyd resin compositions comprise at least 20 wt%, more preferably at least 50 wt%, even more at least 70wt% of unsaturated fatty acid (A) based on the total weight of the alkyd. Preferably, the one or more alkyd resins comprise at most 90wt% unsaturated fatty acid (A), more preferably at most 85 wt% unsaturated fatty acid. A specific example of a suitable alkyd resin is the condensation product of soya oil, phthalic anhydride, and pentaerythritol. Optionally, the one or more alkyds may comprise other building blocks, which might be derived from monocarboxylic acids such as pivalic acid, 2- ethylhexanoic acid, lauric acid, palmitic acid, stearic acid, 4-tert. butyl-benzoic acid, cyclopentane carboxylic acid, naphthenic acid, cyclohexane carboxylic acid, 2,4-dimethyl benzoic acid, 2methyl benzoic acid, benzoic acid, 2,2-dimethylol propionic acid, tetrahydrobenzoic acid, and hydrogenated or non-hydrogenated abietic acid or its isomer. If so desired, the monocarboxylic acids in question may be used wholly or in part as triglyceride, e.g. as vegetable oil, in the preparation of the alkyd resin. If so desired, mixtures of two or more of such monocarboxylic acids or triglycerides may be employed. Advantageously, (A), (B), (C), and (D) are mixed with a solvent comprising at least white spirit, de-aromatized white spirit, furanic based solvents, alkanes and / or aromatic solvents. More preferably, the amount of solvent is in the range of from 0.1 wt% up to 60 wt%, even more preferably in the range of from 2 wt% up to 40 wt%, most preferably in the range of from 3 wt% up to 25 wt%. Unlike for example catalysts and curing agents, solvent concentrations are often calculated as a percentage of the total formulation, notjust the solid content. This is because solvents are volatile components and are designed to evaporate after application, so their role is to adjust the application properties (viscosity, flow, drying time) rather than participate in the final film formation. White spirit also called mineral spirits also known as mineral turpentine, turpentine substitute, and petroleum spirits, depending on the region in the world, is a petroleum-derived clear liquid used as a common organic solvent in painting. White spirit is generally used as a paint thinner, or as a component thereof, though paint thinner is a broader category of solvent. Odourless mineral spirits have been refined to remove the more toxic aromatic compounds. The present invention is furthermore directed to the process for the preparation of an alkyd resin composition, wherein (A) at least one unsaturated fatty acid, (B) at least one polyol, (C) at least a catalyst, and (D) at least one aromatic compound with the following structure: R2 fff / / R3 R1 with R1 = H or CH3 or COOH; R2 = H or CH3; R3 = COOH or form together an anhydride bridge CO-O-OC are added to a reactor to form a reaction medium and the reaction medium is stirred and heated to at least 100°C. At temperatures above 100°C the esterification reaction as described above occurs, and water that is formed during this reaction may leave the reaction medium, accelerating the reaction. Advantageously, the reaction medium is heated to a temperature in the range of from 200° up to 250°C, more preferably in the range of from 225°C up to 245°C. Advantageously, solvent is added, preferably in an amount in the range of from 0.1 wt% up to 60 wt%, more preferably in the range of from 2 wt% up to 40 wt%, even more preferably in the range of from 3 wt% up to 25 wt% relative to the reaction medium. Unlike for example catalysts and curing agents, solvent concentrations are often calculated as a percentage of the total formulation, not just the solid content. This is because solvents are volatile components and are designed to evaporate after application, so their role is to adjust the application properties (viscosity, flow, drying time) rather than participate in the final film formation. The addition of the solvent here is to keep the temperature in the reactor preferably below 250°C. Another advantage of the addition of the solvent is that the viscosity of the reaction medium and / or the final product can be tailored to the desired properties. Advantageously, the solvent comprises at least white spirit, de-aromatized white spirit, furanic based solvents, alkanes and / or aromatic solvents. White spirit also called mineral spirits also known as mineral turpentine, turpentine substitute, and petroleum spirits, depending on the region in the world, is a petroleum- derived clear liquid used as a common organic solvent in painting. White spirit is generally used as a paint thinner, or as a component thereof, though paint thinner is a broader category of solvent. Odourless mineral spirits have been refined to remove the more toxic aromatic compounds. As described earlier, one of the ways to monitor the progress of the process is to measure the acid value (AV) via a titration technique. It is defined as the amount of potassium hydroxide (KOH) in milligrams required to neutralize one gram of the resin sample. This value helps to determine the degree of polymerization and the extent of the reaction during the synthesis of alkyd resin compositions. It is calculated using the following empirical equation 1: AV : _leCÎqHsÏnÎÊÎSÔ'l [equation 1] The acid value (AV) obtained from Equation 1 is then used to calculate the degree of polymerization (or conversion) as a percentage (%), using equation 2: conversion :% [equation 2] with AVO being the acid value before reaction and AVt being the acid value at time t of the reaction. Generally, the reaction is considered completed when a plateau of the curve is reached and preferably when an acid value below and / or equal to 12, more preferably below 9, is measured. This corresponds to a conversion greater than 95%, more preferably greater than 97%. Together with the acid value, another important parameter to measure is viscosity. Viscosity is correlated with the molecular weight of the polymers obtained in the alkyd synthesis reaction by the lVlarkHouwink relationship defined as: [n] : K*l\ / la [equation 3] with [n] being the intrinsic viscosity of the polymer solution, M the molecular weight of the polymer chains in the solution and Kand a being the Mark-Houwink parameter for a specific polymer solution. It might occur that for an obtained acid value that is within specifications, the viscosity value is too low. This is an indication that the stoichiometry of the reaction has resulted in chain lengths that are small in mass and therefore the global molecular weight of the obtained resin is too low. Another way to monitor the progress of the process is to measure the progress via Fourier Transform Infrared (FTIR) spectroscopy or for example H- NMR or another titration technique. Another inventiveness aspect of the obtained novel alkyd based coating formulations, comprising the aromatic compound of the invention, relates to the discovery that during the drying process of the applied alkyd-based coating, the substituted aromatics also participate in the oxidative cross-linking process, thus leading to improved properties of the final coating and drying times. Improved properties include a remarkable increase in film strength, mechanical and chemical resistance and coating hardness. A comparison between the two drying mechanisms of this moiety is depicted in the reaction scheme below. The extra methyl group in theMPA based alkyd, offers extra cross linking in oxidative drying mechanism improving on paint mechanical and chemical properties. @@ â ° J Li PA-based alkyd MPA-based alkyd The substituted group is reactive given that the bond dissociation enthalpies value found was identical to that of toluene (which is a well-known number, namely 375.0 i 8.4 kJ / mol = 89.7 i 2.0 kcal / mol from the Handbook of Bond Dissociation Energies in Organic Compounds; Luo, Y.-R. Ed.; CRC Press: London, U.K., 2003). It is thus expected that radical chemistry can occur that hinges on the abstraction of a hydrogen atom from that moiety as depicted in the reaction scheme below. 0 O O\ / O\ / + H ©® = <!--?? <br-->CH3 o o o H H Additionally, the novel formulation, because of the relative lower viscosity of a MPA based alkyd coating, compared to a similar performing PA based alkyd coating, can rely on the use of less volatile organic solvents (VOCs) (e.g., mineral spirits), which will contribute to a reduction in environmental and health concerns due to their release into the atmosphere during drying. Given these technological advancements and market demands, there is a continuous need to improve the performance and the environmental footprint of alkyd resin-based coatings. Alkyd resin compositions have long been established as one of the most widely used resins in the coatings industry due to their versatile properties, which include good adhesion, gloss, durability, and flexibility. However, recycling once it has been applied on a wall or an object, like a car or a more industrial agricultural machine or building machine as a coating is very difficult. Therefore, there is a great effort taking place to replace all ingredients of the coating by biobased ingredients, while focussing on maintaining the right properties. Some of these ingredients are easier to replace than others. One of the harder ingredients to replace up till now was phthalic anhydride, as it has some unique properties in the coating. Itwas now found that by using the aromatic compounds of the invention, properties of the coating were not only maintained, but some were also even improved. Therefore, the present invention is also directed to the use of at least one aromatic compound with the following structure R2 (is / / R3 R1 with Ri = H or CH3 or COOH; R2 = H or CH3; R3 = COOH or form together an anhydride bridge CO-O-OC; into an alkyd resin composition comprising furthermore (A) at least one unsaturated fatty acid, (B) at least one polyol, (C) at least a catalyst. Advantageously, the alkyd resin composition is further used to formulate an alkyd-based coating. With the use of the above aromatic compound, the chemical resistance is improved. Advantageously, it is used to increase the chemical resistance, preferably water resistance and grease resistance of the resulting alkyd-based coang. Advantageously, the use of the above aromatic compound in an alkyd resin composition and / or alkyd-based coating increases mechanical resistance, more preferably abrasion resistance of the resulting alkyd-based coating. Advantageously, the use of the above aromatic compound in an alkyd resin composition and / or alkyd-based coating increases solvent rub resistance, more preferably MEK rub resistance of the resulting alkyd-based coating. Advantageously, the use of the above aromatic compound in an alkyd resin composition and / or alkyd-based coating increases hardness, tensile strength and tensile e-modulus (elongation at break) of a resulting alkyd-based coang. Advantageously, the use of the above aromatic compound in an alkyd resin composition and / or alkyd-based coating decreases the dark yellowing of a resulting alkyd-based coating. Advantageously, the use of the above aromatic compound in an alkyd resin composition and / or alkyd-based coating decreases the drying time of fresh films of a resulting alkyd-based coating. Advantageously, the use of the above aromatic compound in an alkyd resin composition wherein the alkyd resin is blended with other resin types, preferably acrylic resins, urethane resins and / or phthalic anhydride-based alkyd resins. The following, non-limiting examples and figures are provided to illustrate the invention. Figure 1 illustrates the results of experiment 2. lt shows the acid value versus the reaction time for the samples of the PA005 and MPA001 recipes. Figure 2 illustrates the results of experiment 2. lt shows the conversion versus the reaction time for the samples of the PA005 and MPA001 recipes. Figure 3 illustrates the results of experiment 2. lt shows GPC chromatograms of PA005, MPA001, and commercial Setal 270. Figure 4 illustrates the results of experiment 3. lt shows the acid value versus the reaction time for MPA001 with various catalysts. Figure 5 illustrates the results of experiment 3. lt shows the conversion versus the reaction time for IVIPA001 with various catalysts. Figure 6 illustrates the results ofexperiment 5. ltshows the tensile strength versus the dry layer thickness of clear paint films. Figure 7 illustrates the results of experiment 5. lt shows the E-modulus versus the dry layer thickness of clear paint films. Figure 8 illustrates the results of experiment 6. lt shows the Koning hardness measurements of paint films. Figure 9 illustrates the results of experiment 7. lt shows the solvent rub measurement using MEK of paint films. The following, non-limiting examples are provided to illustrate the invention. Examples Example 1: In a first experiment the evaluation of the bond dissociation energy (BDE) of three components was studied. The following approach was taken: Consider for the organic compounds under interest the equations below: (|) © = 9 CH3 ° H H O 0 O\ / _ o\ / + H ©? <%? ° CH3 o ) H .H 0 M _ M + H. H H (lll) H The aim was to compute the appropriate C-H BDE for these three compounds by high-end quantum chemical methods. Toluene was included, as experimental values for the bond dissociation enthalpies are known (375.0 i 8.4 kJ / mol = 89.7 i 2.0 kcal / mol2. As computational method wB97XD / 6311G(2d,2p) was used this is a high-end density functional (DFT) method, and has a big basis set suitable for the task at hand. The enthalpies are given in Hartree (the energy unit for quantum chemistry; 1 H = 627.51 kcal / mol) and the resulting bond dissociation energy is then given in kcal / mol at the very end. The value for toluene indicates the precision of the method used. Table 1: the calculated BDE (in H and in kcal / mol) for molecules |, II and III. - ______ ______ It can be concluded that the BDE of (ll) is virtually identical to that of toluene. It is thus to be expected that radical chemistry can occur that hinges on the abstraction of a hydrogen atom from that moiety. Example 2: The synthesis of a 3-methylphthalic acid / anhydride (l\ / IPA) based alkyd resin in comparison to the phthalic acid / anhydridebased alkyd resin was performed in an experimental set up constructed to mimic the set ups used in industry as close as possible within the lab. All syntheses were designed to replicate the properties of a commercially available alkyd resin known as Setal 270. The reaction was carried out in a standard 2 L four-neck flask equipped with a thermometer, a nitrogen inlet, an insulated Vigreux column, a Dean Stark water separator, and a reflux condenser. The flask was placed in an electrical heating mantle, which was used to maintain the reaction temperature at 240°C. Mechanical stirring was provided through an overhead stirrer mounted above the flask. To regulate temperature control, xylene was intermittently introduced in 2- 5 mL aliquots via the top of the condenser, specifically when the temperature exceeded 245°C. Nitrogen flowwas maintained throughout the reaction to ensure an inert atmosphere. The progress ofthe syntheseswas monitored by measuring the acid value at various reaction intervals. Once the acid value dropped below 12, viscosity measurements were also conducted to further assess the reaction. The acid value was determined by titrating a known quantity of the reaction mixture, dissolved in 50 mL of a 2:1 toluene / ethanol solution, with approximately 0.1 M KOH in ethanol, using phenolphthalein as a visual indicator. Equation 1 (outlined in the previous section) was employed to calculate the acid value. The conversion during the polymerization process was subsequently determined using the acid value and calculated by applying Equation 2 (also described in the previous section). The viscosity of the resin samples was measured after dilution with white spirit to achieve a solids content of 70%, in accordance with the Setal 270 datasheet. A Thermo Scientific Haake Mars 60 rheometer, configured in a plate- plate setup, was employed for the measurements. The test was conducted at a constant rotational speed of 50 RPM, with the temperature maintained at 23°C for a duration of 180 seconds. The average viscosity from the final 10 seconds of the measurement period was used for analysis. The most promising final products, along with selected intermediate samples, were analysed via Gel Permeation Chromatography (GPC) to determine molecular weight and molecular weight distribution. The results were compared against the reference resin Setal 270. GPC analysis was conducted using an Ecom chromatograph with tetrahydrofuran (THF) as the solvent, an ultraviolet (UV) detectorfrom Ecom, and a refractive index (Rl) detectorfrom Lab Alliance. The best result of all the produced alkyd resins recipe containing phthalic anhydride (PA) comparable to the reference Setal 270 was used as reference. When inserting 3-methyl phthalic anhydride (MPA), the recipe was slightly modified to account for the additional methyl group present in MPA (compared to PA). The resulting formulation, designated as MPA001, is detailed in Table 2 alongside the original PA005 recipe. Table 2: Comparison of PA005 and MPA001 recipes. As with the PA-based syntheses, the acid value of the MPA reaction mixturewas monitored over time, and the conversion was calculated accordingly. Figures 1 and 2 present the acid value and conversion of MPA001, compared to PA005. It can be observed from the figures that the polyesterification of lVlPA proceeded at a slower rate compared to that of PA that might be due to steric hindrance. This was an indication that a catalyst might be required, therefore an investigation into catalytic effect will be discussed in next experiment. Gel Permeation Chromatography (GPC) measurements were conducted on the final IVIPA001 sample to determine the chain length and distribution, with the resulting chromatogram shown in Figure 3 alongside overlays of PA005 and Setal 270. The chromatogram illustrates an almost perfect overlay of all three samples, particularly PA005 and MPA001, indicating that the alkyd resins synthesized are nearly identical. This similarity allows for direct comparisons in evaluating potential differences in the properties of both the resins and the paints derived from them. Differences in molecular weight or molecular weight distribution can be considered negligible as variables. Furthermore, both lab- synthesized resins are comparable to the commercially available Setal 270, which can serve as a reliable reference. Example 3: The synthesis of the IVIPA-based alkyd resin composition with various catalyst were tested. Various catalysts are known to accelerate esterification reactions, including alkyd resin synthesis. In this study, catalysts from different chemical groups were selected for comparison. The selected catalysts and their respective amounts are listed in Table 3. Table 3: Catalyst that were tested and the concentration Catalyst ÈÏÊÆ; Type Hydrochloric acid (HCI) 0.1 Inorganic acid Lithium hydroxide (LiOH) 0.1 Inorganic base pgâl)uene-sulphonic acid (p- 01 Organic acid Fascat 4201 0.1 Dibutyltin oxide Fascat 4350 0.1 Dibutyltin oxide Fascat 41003 0.3 Monobutyltin hydroxide oxide The catalysts evaluation was conducted within the complete alkyd resin synthesis reaction. The graphs depicting the acid value and conversion versus reaction time for all the catalysts listed in Table 3 are presented in Figures 4 and 5, respectively. As can be seen from the figures, Fascat 4100, p-toluene sulphonic acid, hydrochloric acid and lithium hydroxide outperformed Fascat 4201 and Fascat 4350 which showed moderate catalytic activity (not shown here). The data furthermore show that HCl did not perform well in the IVIPA001 synthesis, despite being one of the best catalysts in the PA005 reaction (not showed in this patent application), thus for PA. This was unexpected. Polyesterification with Fascat4100 proceeds the fastest. The rapid release of water in a short period caused condensation within the flask instead of in the condenser. When these water droplets dripped back into the 240°C reaction mixture, they immediately began to boil, resulting in eruptions, splattering, and even foaming of the mixture. This behaviourwas not observed when using LiOH as a catalyst. Although LiOH exhibited slightly lower catalytic efficiency compared to Fascat 4100, the improved control over the reaction outweighed the longer reaction time required. As a result, all further MPA syntheses were performed using LiOH as the catalyst. Additionally, the choice of LiOH is further justified by the trend within the industry to move away from tin-based catalysts due to environmental concerns. LiOH has emerged as a promising alternative that is currently under exploration. Example 4: Two types of paintstranslucent and opaquewere prepared. For each type, three formulations were developed, utilizing the three alkyd resins from this research: Setal, IVIPA-based, and PA-based. The formulation for the translucent paint is described in table 4. Table 4: Formulations of clear paints, m / m% listed Paint recipe PA005 MPA001 Setal 270 Resin 79.00 79.00 79.00 White spirit 18.15 18.15 18.15 Cobalt drying agent 2.50 2.50 2.50 Mekoxime 0.35 0.35 0.35 The formulation for the opaque paint is reported in table 5. Table 5: Formulations of opaque paints, m / m% listed Paint recipe PA005 MPA001 Setal 270 Resin 56.50 56.50 59.34 Titanium dioxide 23.42 23.42 24.59 Barium sulphate 5.09 5.09 5.34 Shellsol D40 13.05 13.05 8.58 $$$" drying 1.95 1.95 2.14 Mekoxime 0.31 0.31 0.32 Example 5: Film strength assessment of the obtained paints, of example 4, was performed. The tensile strength and tensile modulus have been determined for various layer thicknesses of the PA005 and MPA001 clear paints using a Zwick Roell Z010 tensile tester. The tensile strength is shown in figure 6 whilst the E- modulus in figure 7. Figure 6 illustrates the relationship between the tensile strength in MPa on the y-axis and layer thickness in micrometers (um) on the x-axis for the two coatings: PA-005 (represented by open circles and a dashed line) and MPA-001 (represented by solid dots and a solid line). Figure 7 illustrates the relationship between the variable "E" (representing Youngs elastic modulus) in MPa on the y-axis and layer thickness in micrometers (pm) on the x-axis. Both tensile strength and E-modulus were significantly higher for thinner layers (less than 200 um), likely due to molecular orientation or other structural factors that have a greater impact at reduced thicknesses. Below this threshold, MPA demonstrated significantly better performance compared to PA. Notably, for layers with thicknesses between 50 and 100 um, MPA exhibited values that were double those of PA. This range between 50 and 200 um, as emphasised by the dashed-dotted area in the graphs is also commonly the layer thickness applied in practical coating applications. Example 6: The Koning hardness or Pendulum Hardness of the samples were measured. The instrument consists of a pendulum which is free to swing on two balls resting on a coated test panel. The pendulum hardness test is based on the principle that the amplitude of the pendulum's oscillation will decrease more quickly when supported on a softer surface. The hardness of any given coating is given by the number of oscillations made by the pendulum within the specified limits of amplitude determined by accurately positioned photo sensors. An electronic counter records the number of swings made by the pendulum. Standard hardness tests relate oscillation damping to surface hardness. A glass panel was coated with a 60 um wet film, held at 23°C and 50% RH and the hardness development in time was monitored with the Konig test. It measures the time taken for the amplitude to decrease from 6° to 3°. The Konig pendulum is triangular with an adjustable counterpoise and swings on two ball bearings of 5mm diameter which rest on the test surface. The measured König hardness of three coatings Setal 270, PA005, and MPA001, presented in Figure 8, exhibits that the commercial Setal displays moderate hardness at around 25 swings, comparable to the PA005 which shows the lowest hardness, slightly above 20 swings. In contrast, MPA001 has the highest hardness, reaching about 50 swings, making it significantly harder than both Setal 270 and PA005. These results suggest that MPA001 has a higher cross-linked alkyd film, which might be from to the methyl moiety offering an extra cross-linking group during the oxidative drying process. MPA therefore has superior resistance to mechanical wear or deformation, when compared to paints cured using commercial formulation with PA. Example 7: The solvent rub test is used to determine the degree of cure of a coated film by the paint film resistance to a specified solvent. The solvent rub test is usually performed using methyl ethyl ketone (MEK) as the solvent. This test measures the surface of a coated film with a cloth soaked with MEK until failure or breakthrough of the film occurs. The type of cloth, the stroke distance, the stroke rate, and approximate applied pressure of the rub are specified. The numbers of rubs are counted as a double rub: one rub forward and one rub backward constitutes one rub count. Figure 9 illustrates that theMEK resistance ofthree coatings prepared with alkyds resins Setal 270, PA005 and MPa001. Setal and PA exhibit similar performance with around 60 double rubs each, indicating moderate resistance. In contrast, IVIPA001 significantly outperforms both with approximately 100 double rubs, demonstrating a higher durability compared to the other two. This suggests that IVIPA001 has superior resistance to abrasion or chemical wear likely due to its higher cross-linked alkyd backbone.

Claims

1. An alkyd resin composition comprising (A) at least one unsaturated fatty acid, (B) at least one polyol, (C) at least one catalyst and (D) at at least one aromatic compound with the following structure: R2 {ÎERB / R3 R1 with R1 = H or CH3 or COOH; Rz = H or CH3; R3 = COOH or together they form an anhydride bridge CO-O-OC.

2. Composition according to claim 1, where the catalyst (C) is a catalyst belongs to the group of metal salts and / or inorganic acids and / or bases, organic acids and / or bases and / or organometallic acids and / or bases, preferably lithium hydroxide, butyltin acid, mono-butyltin oxide, di-butyltin oxide, hydrochloric acid and / or p-toluenesulfonic acid.

3. Composition according to claim 1 or 2, where the polyol (B) a is a trivalent alcohol and / or a tetravalent alcohol, preferably trimethylolpropane, glycerol and / or (di)pentaerythritol.

4. Composition according to one of the preceding conclusions, whereby the fatty acid (A) includes fatty acids derived from natural oils, preferably derived from soybean oil, linseed oil, sunflower oil, rapeseed oil, camelina oil, safflower oil, palm oil and / or combinations thereof, more preferably derived from soybean oil, rapeseed oil, linseed oil, camelina oil and sunflower oil.

5. Composition according to one of the preceding conclusions, whereby the aromatic compound a 3- based on biological raw materials methyl phthalate anhydride (3-MPA), 3-based on biological raw materials methyl phthalic acid (3-MPA), 3,6- based on biological raw materials dimethylphthalic acid (DMPA), 3,6- based on biological raw materials dimethyl phthalate anhydride (DMPA), fossil fuel-based 4- methyl phthalate anhydride (4-MPA), fossil fuel-based 4- methyl phthalic acid (4-MPA), fossil-based hemimellitic acid (HMA), fossil-based hemimellitic anhydride (HMA), fossil-based trimellitic anhydride (TMA) and / or on fossil fuel-based trimellitic acid (TMA) is, preferably on 3-MPA and / or DMPA based on biological raw materials, preferably more on 3-MPA based on biological raw materials.

6. Composition according to one of the preceding conclusions, whereby the amount of aromatic compound lies in the range of 5 to 50 wt.% relative to the total solid content of the resin, preferably in the range of 10 to 40 wt.%, preferably in the range of 10 to 30 wt.%.

7. Composition according to one of the preceding conclusions, whereby the alkyd resin composition further comprises phthalic anhydride (PA).

8. Composition according to conclusion 7, where the molar ratio between (i) the total amount of aromatic compound and (ii) PA in the range of 100:1 up to 1:100 lies, preferably in the range of 10:1 to 1:10, more preferably in the range from 5:1 to 1:

5.

9. Composition according to one of the preceding conclusions, whereby the the amount of catalyst is in the range of 0.001 to 0.8 wt.%, preferably in the range of 0.005 to 0.3 wt.%.

10. Composition according to one of the preceding conclusions, where (A), (B), (C) and (D) are mixed with a solvent containing at least turpentine, deodorized turpentine, furan-containing solvents, alkanes and / or includes aromatic solvents.

11. Composition according to claim 10, where the amount of solvent in The range of 0.1 wt.% to 60 wt.% lies, preferably, in the range of 2 wt.% up to 40 wt.%, preferably in the range of 3 wt.% to 25 wt.%.

12. Method for the preparation of an alkyd resin composition, whereby (A) at at least one unsaturated fatty acid, (B) at least one polyol, (C) at least one catalyst, and (D) at least one aromatic compound with the following structure: R2 ÖíRB / R3 R1 where R1 = H or CH3 or COOH; R2 = H or CH3; R3 = COOH or together they form an anhydride bridge CO-O-OC be added to a reactor to a to form a reaction medium and the reaction medium is stirred and heated to ten at least 100°C.

13. Procedure in accordance with claim 12, whereby the reaction medium is heated up to a temperature in the range of 200°C to 250°C, preferably in the range from 225°C to 245°C.

14. Method in accordance with claims 12 and 13, whereby solvent is added, preferably in an amount in the range of 0.1 wt.% to 60 wt.%, more preferably in the range of 2 wt.% to 40 wt.%, even more at preference in the range of 3 wt.% to 25 wt.% compared to the reaction medium.

15. Method in accordance with conclusions 12 through 14, whereby the process is stopped when a calculated acid reaches a plateau and / or values ​​lower than and / or equal to 12, preferably lower than 9.

16. Use of at least one aromatic compound with the following structure R2 (EEE- <?) / R3 R1 where R1 = H or CH3 or COOH; R2 = H or CH3; R3 = COOH or they form together an anhydride bridge CO-O-OC; in an alkyd resin composition which further comprises (A) at least one unsaturated fatty acid, (B) at least one polyol, (C) at least one catalyst.

17. Use in accordance with claim 16 for the formulation of an alkyd coating.

18. Use in accordance with claims 16 and 17 to increase the chemical resistance, preferably water resistance and grease resistance, of the obtained alkyd coating.

19. Use according to conclusions 16 and 17 to the mechanical resistance, at preference to increase the wear resistance of the resulting alkyd coating.

20. Use according to claims 16 and 17 to the solvent friction precipitate, at preference to increase the MEK rub resistance of the resulting alkyd coating.

21. Use according to claims 16 and 17 to determine the hardness, tensile strength and to increase the tensile modulus (elongation at break) of a resulting alkyd coating.

22. Use according to conclusions 16 and 17 to the dark yellowing of a to reduce the resulting alkyd coating.

23. Use according to conclusions 16 and 17 to the drying time of fresh films of to shorten a resulting alkyd coating.

24. Use in accordance with claim 16, whereby the alkyd resin is mixed with other types of resin, preferably acrylic resins, urethane resins and / or alkyd resins based on phthalic anhydride.

Images