Method to process rosin, processed rosin and uses thereof

Abstract

The present disclosure relates to a method for obtaining a processed rosin, the method comprising the following steps: obtaining a gum rosin; adding 0.01% to 5.0% (wantioxidant / wrosin) of a natural antioxidant to the gum rosin to obtain a mixture, provided the natural antioxidant is not gallic acid, caffeic acid or oxalic acid; stirring the mixture at a temperature ranging from 80 °C to 300 °C, for 5 h to 20 h, to obtain a processed rosin; wherein the processed rosin is free of synthetic organic antioxidants, or products thereof. A processed rosin obtainable by the disclosed methods, its uses and articles comprising the processed rosin are also disclosed.

Description

D E S C R I P T I O NMETHOD TO PROCESS ROSIN, PROCESSED ROSIN AND USES THEREOFTECHNICAL FIELD

[0001] The present disclosure relates to a method for the oxidative stabilization of rosin at high temperatures, including esterification or other rosin conversion processes, using natural antioxidants including, among others, phenolic compounds, vitamins, and carotenoids, with or without the addition of iodine, with or without inert atmosphere that led to processed products without contamination with synthetic organic antioxidants or products thereof.BACKGROUND

[0002] Rosin, also known as colophony or gum rosin, is the non-volatile fraction, obtained as a transparent or translucent solid, after distillation of the resin exuded by various Pinus species (pine trees), mainly P. elliottii, P. pinaster, and P. massoniana [1], Rosin can also be referred to as wood rosin or tall oil rosin, if obtained from the solvent extraction of wood chips from pine stumps, followed by distillation; or from the distillation of crude tall oil (CTO), a by-product of the Kraft pulp industry [1],

[0003] Although the composition of these three types of rosin differs, they are all primarily composed of monocarboxylic diterpenic resin acids, followed by smaller amounts of other components such as fatty acids, non-volatile neutral non-hydrolysable compounds. The most abundant resin acids include abietic, dehydroabietic, pimaric, isopimaric, communic, palustric, neoabietic, and levopimaric acids [1], Among the neutral substances, diterpenic alcohols, hydrocarbons, and aldehydes are the most common, including a-pinene, |3-pinene, and camphene, among others. Regarding the fatty acids, oleic and linoleic acids are the most common [1],

[0004] Rosin is used in various industrial applications, including adhesives, coatings, printing inks, chewing gums, and cosmetics [1], Normally, during rosin processing towards final products, raw rosin is subjected to thermal processing at high temperatures (200 - 270°C) to tune some of its physical properties, such as to increasethe softening point, to decrease the acid number (acidity), to decrease its crystallinity, and improve its stability. However, rosin can easily undergo oxidation, which may result in degradation, reduced quality, and final products performance [1], Moreover, the oxidation of rosin leads to an undesired darkening (high Gardner colour value), which is a major limitation on its applications. Oxidation is primarily associated with the high reactivity of the conjugated double bond system present in the structure of abietic-type resin acids, which is highly prone to oxidation in the presence of oxygen, heat, metal ions, and light [1], Resin acids oxidation leads to the formation of endo- and hydroperoxides, epoxides, as well as hydroxyl and carbonyl groups [1],

[0005] Because raw rosin is commonly submitted to heat and exposed to oxygen during processing, numerous techniques have been developed to prevent rosin oxidation, mainly focused on the chemical conversion of the conjugated double bonds. For instance, isomerization / dehydrogenation and hydrogenation reactions have been used [1], During isomerization / dehydrogenation reactions, carried out at temperatures ranging from 200 to 270 °C and in the presence of catalysts such as Pd / C, Ni, I2, h / FeCh, and H / FeBrs, abietic-type resin acids undergo isomerization and dehydrogenation into dehydroabietic acid which, due to the presence of an aromatic moiety, instead of a conjugated double bond system, is responsible for the increased oxidative stability and light colour of the resulting rosin [1], Alternatively, the oxidative stability of rosin can be significantly enhanced through hydrogenation of the double bonds, which leads to dihydro- and tetrahydroabietic acids [1], To decrease even more the oxidation and maintain a light colour in the final rosin product, these processes can be carried out using inert atmosphere conditions.

[0006] Another common rosin transformation involves its esterification by reaction with an alcohol or polyol, such as methanol, glycerol, ethylene glycol, and pentaerythritol, to form esters, which is typically carried out at high temperatures (200 - 270 °C) [1], leading to rosin ester derivatives for a wide range of applications [1], Esterification partially contributes to increase abietic-type resin acids oxidative stability through the reduction of the acid number [1], However, like rosin, these esters can still undergo oxidation due to the presence of the conjugated double bonds of resin acids, which leads to darkening and loss of properties, thereby restricting their use [1],

[0007] Therefore, the oxidative stability of rosin and rosin derivatives can also be improved through the addition of synthetic antioxidants during the thermal processing and esterification reactions at high temperatures. An antioxidant is a substance that can prevent or minimize the oxidative degradation of a material by inhibiting the formation of free radicals or by neutralizing free radicals before they can react with the material [2], Synthetic antioxidants are used in rosin thermal processing because they provide thermal stability, consistent performance, and reliable protection against oxidation, at the high temperatures used during rosin processing.

[0008] There are two main groups of antioxidants, distinguished based on their oxidation inhibition mechanism: namely primary and secondary antioxidants [2], Primary antioxidants, also known as free radical scavengers, are generally phenolic compounds that inhibit the formation of free radicals like peroxide (ROO») or alkoxy (RO») by donating a hydrogen atom from their hydroxyl groups to the free radical, forming a stable molecule. Examples of synthetic primary antioxidants used in rosin industries include butylated hydroxytoluene (BHT), butylated hydroxyanisole (BHA), tert-butyl hydroquinone (TBHQ), and pentaerythritol tetrakis[3-[3,5-di-tert-butyl-4-hydroxyphenyl] propionate (Irganox 1010) [2],

[0009] Secondary antioxidants, or peroxide decomposers, act by inhibiting peroxide formation and hydroperoxide decomposition into free radicals. They are highly effective when combined with primary antioxidants, creating a synergistic relationship that maximizes the oxidative stability of the materials. One example is tris(nonylphenyl) phosphite (TNPP) [2], Moreover, there are some dual-function synthetic antioxidants, like calcium ethyl(3,5-di-tert-butyl-4-hydroxybenzyl) phosphonate (Irganox 1425) and 4,4'-thiobis(2-tert-butyl-5-methylphenol) (Lowinox TBM-6), that combine free radical deactivation with decomposition of oxidation products [2],

[0010] For example, Wang showed that light-coloured glycerol rosin ester could be produced using BHT, Lowinox TBM-6, 2,2'-methylene bis(4-methyl-6-tert-butylphenol), or octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate. The author emphasizes that the factors influencing the colour, softening point, and acid number of rosin esters are the antioxidant type and dosage, the reaction temperature and time, and the procedures used for the addition of glycerol and antioxidants. Moreover, it is suggestedthat the reaction should be carried out under an inert atmosphere to minimize the effects of the oxidation. The results showed that 0.5% of Lowinox TBM-6 with a temperature in the range 260-270 °C, reaction time of 6-8 h, and a molar ratio 2.5:1 (rosi antioxidant, mol mol-1) were the best conditions to produce light-coloured rosin ester [3],

[0011] Mota et al. also showed that pentaerythritol rosin ester could be prepared using synthetic antioxidants, including Irganox 1010, Irganox 1425, and Lowinox TBM-6. The results confirmed that Lowinox TBM-6 effectively retarded the darkening of the resin, especially under inert atmosphere, with Gardner colour values around 4. They reiterate that the use of antioxidants during the esterification was crucial to maintain the lightcolour of native resin [4],

[0012] Documents W02000017280A1, WO2016154456A1, US2729660A, US3310575A, US3423389A, US20110034669A1, US6939944B2, CN112322189 exploit the use of synthetic antioxidants, such as Irganox 1425, Lowinox TBM-6, BHT, BHA, and TBHQ, in rosin processing [5-12], Regardless, all of these documents are silent on the use of natural antioxidants.

[0013] Synthetic antioxidants, such as those previously mentioned, are resistant to the high temperatures employed in the rosin processing, and therefore widely used in several industries. However, concerns over the potential health and environmental risks associated with these compounds and products thereof, have prompted the search for safer and greener alternatives.

[0014] These facts are disclosed in order to illustrate the technical problem addressed by the present disclosure.GENERAL DESCRIPTION

[0015] The present disclosure relates to a method for the oxidative stabilization of rosin during thermal processing at high temperatures (preferably between 80 °C and 300 °C), including esterification with different polyols, or other rosin conversion processes, using natural antioxidants including, among others, phenolic compounds, vitamins, and carotenoids, instead of synthetic antioxidants (such as Lowinox TBM-6).

[0016] Natural antioxidants, while effective in some applications such as in pharmaceutical or food applications, tend to degrade under high temperatures and conditions such as those involved in the rosin processing. Surprisingly, the method of the present disclosure allows to obtain a thermally processed rosin using natural antioxidants for oxidative stabilization of rosin. Moreover, natural antioxidants can be combined with iodine and / or an inert atmosphere for improved oxidative stabilization. Unpredictably, these approaches lead to modified rosin with similar or improved properties adequate for further processing / application (Gardner colour, softening point, and acid number) and similar chemical composition compared to those of rosin obtained using synthetic antioxidants. The resulting rosin products are free of synthetic organic compounds derived from the use of synthetic antioxidants and therefore, without the health and environmental risks associated with their presence.

[0017] The disclosed method not only contributes to the oxidative stability of rosin, using natural antioxidants but also aligns with the principles of circular economy, as these compounds can be obtained from agro-food industry by-products and wastes. Furthermore, to achieve light-coloured rosin, natural antioxidants can be combined with iodine and / or inert atmosphere that contribute to improved oxidative stability, which typically can occur at high temperatures, enhancing the overall quality of rosin. Moreover, rosins obtained using natural antioxidants show similar or improved values of Gardner colour, softening point, and acid number compared to those obtained using synthetic antioxidants.

[0018] For the scope of the present disclosure, the term "synthetic antioxidants" relates to artificially manufactured chemical compounds designed to inhibit oxidation and extend the shelf life, stability, and performance of various.

[0019] For the scope of the present disclosure, the term "natural antioxidants" refers to compounds found in nature that prevents the oxidation of other molecules. These antioxidants are typically of vegetal origin.

[0020] For the scope of the present disclosure, the term "polyol" refers to polyalcohols such as glycerol and pentaerythritol.

[0021] In an embodiment, natural antioxidants include, but not limited to, phenolic compounds, vitamins and carotenoids, provided the natural antioxidant is not gallic acid, caffeic acid or oxalic acid. In particular, phenolic compounds include, but not limited to quercetin, resveratrol, curcumin, tannins, ellagic acid, ferulic acid, thymol, eugenol, vanillin, carvacrol, kaempferol, apigenin, luteolin, chlorogenic acid, cinnamic acid, rosmarinic acid, epicatechin, rutin, hesperidin, naringenin, p-coumaric acid, sesamol, and catechin derivatives. Vitamins include, but not limited to, ascorbic acid (vitamin C), tocopherols (vitamin E) and tocotrienols, retinol (vitamin A), phylloquinone, and menaquinones (vitamin K). Carotenoids include, but not limited to, beta-carotene, lycopene, lutein, zeaxanthin, and astaxanthin.

[0022] In an embodiment, the natural antioxidants can be added at the beginning or along the processing in concentrations between 0.01% and 5.0% (w / w) relative to the weight of rosin used in the processing.

[0023] In a further embodiment, iodine (I2) with concentrations ranging from 0.01% to 5.0% (w / w) relative to the weight of rosin can be added at the beginning or along the processing. Surprisingly, the use of iodine (which is not an antioxidant) resulted in a synergistic effect that improved the oxidative stability of the thermally processed rosin.

[0024] In a further embodiment, an inert atmosphere, for example of nitrogen can be added, resulting in a synergic effect with both the addition of the natural antioxidant and iodine.

[0025] Surprisingly, the method of the present disclosure originates thermally processed rosin with quality parameters (Gardner colour, softening point, and acid number values) equivalent or improved when compared to those obtained with traditional methods using synthetic antioxidants. Additionally, the chemical composition of rosin after thermal processing and esterification with natural antioxidants is remarkably similar to that obtained using the synthetic alternative.

[0026] The present disclosure relates to a method for obtaining a processed rosin, the method comprising the following steps:obtaining a gum rosin;adding 0.01% to 5.0% (wantioxidant / wrOsin) of a natural antioxidant to the gum rosin to obtain a mixture, provided the natural antioxidant is not gallic acid, caffeic acid or oxalic acid;stirring the mixture at a temperature ranging from 80 °C to 300 °C, for 5 h to 20 h, to obtain a processed rosin;wherein the processed rosin is free of synthetic organic antioxidants, or products thereof.

[0027] Surprisingly, despite the technical prejudice that natural antioxidants typically degrade and lose efficacy under the high temperatures required for rosin processing, the present method achieves unexpected oxidative stabilization between 80 °C and 300 °C, yielding a processed rosin with physical-chemical properties— specifically Gardner colour, softening point, and acid number— that are equivalent or superior to those obtained with traditional synthetic organic antioxidants. Furthermore, an inventive aspect of this process is the discovery of a non-obvious synergistic effect between natural antioxidants and iodine (a non-antioxidant), which further enhances the oxidative stability and light color of the resulting products without the health and environmental risks associated with synthetic additives.

[0028] In an embodiment for better result, the concentration of the natural antioxidant ranges from 0.1% to 0.5% (wantioxidant / wrasin), preferably from 0.15% to 0.3% (Wantioxidant / Wrosin).

[0029] In an embodiment for better result, the natural antioxidant is selected from a list comprising phenolic compounds, vitamins, carotenoids, and mixtures thereof.

[0030] In an embodiment for better result, the phenolic compound is selected from a list comprising quercetin, resveratrol, curcumin, tannins, ellagic acid, ferulic acid, thymol, eugenol, vanillin, carvacrol, kaempferol, apigenin, luteolin, chlorogenic acid, cinnamic acid, rosmarinic acid, epicatechin, rutin, hesperidin, naringenin, p-coumaric acid, sesamol, catechin derivatives, and mixtures thereof.

[0031] In another embodiment for better result, the vitamin is selected from a list comprising ascorbic acid, tocopherols, tocotrienols, retinol, phylloquinone, menaquinones, and mixtures thereof.

[0032] In yet another embodiment for better result, the carotenoid is selected from beta-carotene, lycopene, lutein, zeaxanthin, astaxanthin, and mixtures thereof.

[0033] In a preferred embodiment for better result, the natural antioxidant is alphatocopherol, thymol or mixtures thereof.

[0034] In an embodiment for better result, the method further comprises the step of adding 5% to 15% (wpoiyoi / wrosin) of a polyol to the mixture of gum rosin and natural antioxidant, to obtain a rosin ester. In an embodiment, the polyol is selected from a list comprising glycerol, pentaerythritol, or mixtures thereof.

[0035] In an embodiment for better result, iodine is added to the mixture comprising gum rosin and natural antioxidant. In a further embodiment, iodine is added to the mixture comprising gum rosin, natural antioxidant and polyol.

[0036] In an embodiment for better result, the concentration of iodine ranges from 0.01% to 5.0% (Wiodine / Wrosin), preferably 0.1% to 0.3% (Wiodine / Wrosin).

[0037] In an embodiment for better result, the method is carried out in an inert atmosphere, preferably nitrogen atmosphere.

[0038] In an embodiment for better result, the mixture is stirred at a temperature ranging from 160 °C to 270 °C, preferably 200 °C to 265 °C.

[0039] In an embodiment for better result, the mixture is stirred for 8 h to 10 h, preferably for 8 h.

[0040] In an embodiment for better result, the gum rosin has a Gardner colour value ranging from 3 to 10, softening point ranging from 65 to 95 °C, and acid number ranging from 120 to 190 mg KOH g1. In a further embodiment, the gum rosin has a Gardner colour value of 8.5, softening point of 76.5 °C, and acid value of 172.6 mg KOH g1.

[0041] In an embodiment for better result, the method comprises the following steps:obtaining a gum rosin;adding 0.15% (waiPha-tocopheroi / wrosin) of alpha-tocopherol and 0.05% (wiOdine / wrosin) of iodine to the gum rosin under nitrogen atmosphere, to obtain a mixture; heating the mixture at 160 °C;adding 11% (wgiyCeroi / wrosin) of glycerol to the mixture;stirring the mixture at 275 °C, for 8 h, to obtain a processed rosin.

[0042] The present disclosure also relates to a processed rosin obtainable by the method of the present disclosure, wherein the processed rosin is free of synthetic organic antioxidants, or products thereof.

[0043] In an embodiment for better result, the processed rosin has a Gardner colour value ranging from 4 to 9, softening point ranging from 70 to 95 °C, and acid number ranging from 110 to 160 mg KOH g1.

[0044] In another embodiment for better result, the processed rosin is a rosin ester and has a Gardner colour value ranging from 2 to 8, softening point ranging from 75 to 125 °C, and acid number ranging from 5 to 35 mg KOH g1. Preferably, a Gardner colour value ranging from 2 to 4; softening point ranging from 75 to 115 °C, and an acid number ranging from 5 to 25 mg KOH g1.

[0045] In an aspect, the present disclosure relates to the use of the processed rosin of the present disclosure as a tackifier, binding agent, viscosity controller, pigment coating, or cross-linking agent.

[0046] The present disclosure also relates to articles comprising the disclosed processed rosin. In an embodiment, the article is a cosmetic product, a depilatory wax, an adhesive, a printing ink, a chewing gum, a band aid, a paper, a pharmaceutical composition, a road-marking paint, a paint, a water-based adhesive, a hotmelt adhesive, a glue, a solvent-based adhesive, a varnish, or an animal nutrition product.

[0047] The method of the present disclosure, achieves unexpected oxidative stability and light colour at high temperatures through a surprising synergy between natural antioxidants and iodine, resulting in a bio-based rosin with properties that match or exceed those of traditional synthetic alternatives.BRIEF DESCRIPTION OF THE DRAWINGS

[0048] The following figures provide preferred embodiments for illustrating the disclosure and should not be seen as limiting the scope of invention.

[0049] Figure 1. Schematic representation of an embodiment of the disclosed method that combines the use of natural antioxidants, iodine, and inert atmosphere for the oxidative stabilization of rosin during thermal processing at high temperatures.

[0050] Figure 2. Schematic representation of an embodiment of the disclosed method that combines the use of natural antioxidants, glycerol, iodine , and inert atmosphere for the oxidative stabilization during rosin esterification at high temperatures.

[0051] Figure 3. Embodiment of GC-MS chromatogram of a rosin sample after thermal processing using the disclosed method, with 0.3% of alpha-tocopherol and 0.3% of iodine under inert atmosphere .

[0052] Figure 4. Embodiment of chemical composition (%) of raw rosin and rosin after thermal processing at 265 °C for 8 h with alpha-tocopherol, thymol, with or without iodine, under inert atmosphere; or LowinoxTBM-6 (comparative data).

[0053] Figure 5. Embodiment of FTIR-ATR spectra of raw rosin and rosin esterified with glycerol using natural antioxidant (thymol and alpha-tocopherol with iodine) or Lowinox TBM-6 (comparative data) at 265 °C for 8 h under inert.

[0054] Figure 6. Embodiment of the visual aspect of the of rosin before and after thermal processing using natural antioxidants by the method of the present disclosure (the samples in the illustration refer to the use of alpha-tocopherol with iodine in inert atmosphere). Dashed lines in the chemical structures refer to the different positions of the double bonds in the abietic type resin acids.

[0055] Figure 7. Embodiment of the visual aspect of the of rosin before and after glycerol esterification using natural antioxidants by the method of the present disclosure (the samples in the illustration refer to the use of alpha-tocopherol with iodine in inert atmosphere). Dashed lines in the chemical structures refer to the different positions of the double bonds in the abietic type resin acids.DETAILED DESCRIPTION

[0056] The present disclosure relates to a method for obtaining a processed rosin, the method comprising the following steps: obtaining a gum rosin; adding 0.01% to 5.0%(wantioxidant / wrosin) of a natural antioxidant to the gum rosin to obtain a mixture, provided the natural antioxidant is not gallic acid, caffeic acid or oxalic acid; stirring the mixture at a temperature ranging from 80 °C to 300 °C, for 5 h to 20 h, to obtain a processed rosin; wherein the processed rosin is free of synthetic organic antioxidants, or products thereof. A processed rosin obtainable by the disclosed methods, its uses and articles comprising the processed rosin are also disclosed.

[0057] In an embodiment, gum rosin from Pinus elliottii with a Gardner colour value of 8.5, softening point of 76.5 °C, and acid value of 172.6 mg KOH g1is used as example of starting material. Natural antioxidants, namely alpha-tocopherol or thymol, were applied duringthermal processing and esterification reactions at high temperatures (e.g.265 °C), as examples. For comparison, LowinoxTBM-6 was used as synthetic antioxidant. Glycerol was the polyol used as an example for rosin esterification.

[0058] The method of the present disclosure solely uses natural organic antioxidants, i.e., no synthetic organic antioxidants are used, making the obtained rosin a 100% biobased product, free of synthetic organic compounds. This surpasses a long-felt need of reducing the health and environmental risks of rosin, associated with contamination with synthetic antioxidants or other organic compounds thereof.

[0059] In an embodiment, a mixture of rosin and 0.01% to 5.0% (wantioxidant / wrosin) of the natural antioxidant is prepared and stirred for a certain time, preferably for 8 h, and at an established temperature between 80 °C and 300 °C, preferably between 200 and 300°C, more preferably at 265°C.

[0060] In an embodiment, a mixture of rosin and the natural antioxidant (between 0.01% and 5.0% (wantioxidant / wrasin)) is prepared and stirred for a certain time. Iodine (between 0.01% and 5.0% (wiOdine / wrasin)) may be added at the beginning or along the processing. Thermal processing occurs for a certain time, and at an established temperature between 80 °C and 300 °C, preferably between 200 °C and 300 °C. In a preferred embodiment, the reaction (thermal processing) occurs for 8 h, at 265 °C under an inert atmosphere of nitrogen (Figure 1).

[0061] In an embodiment, the method of the present disclosure can be carried out with or without an inert atmosphere, preferably a nitrogen atmosphere. The thermalprocessing method may be carried out in any suitable vessel or flask that permits stirring and heating and that can be performed under an inert atmosphere.

[0062] In another embodiment, the method of the present disclosure is a rosin esterification process. The esterification may be carried out with or without inert atmosphere, preferably a nitrogen atmosphere. Thermal processing may be carried out in any suitable vessel or flask that permits stirring and heating and that can be performed under an inert atmosphere. In an embodiment, a mixture of rosin, the natural antioxidant (between 0.01% and 5.0% (wantioxidant / wrosin)), and 5.0 to 15.0% (wgiyCeroi / w rosin) of glycerol is prepared and stirred for a certain time, preferably for 2 h to 6 h. The esterification process occurs for a certain time and at an established temperature, preferably between 80 °C and 300 °C.

[0063] In a preferred embodiment, a mixture of rosin, the natural antioxidant (between 0.01% and 5.0% (wantioxidant / wrosin)), and 5.0 to 15.0% (wgiyCeroi / w rosin) of glycerol is prepared and stirred for a certain time, preferably for 2h to 6h. Iodine (between 0.01% and 5.0% (wiOdine / wrasin)) may be added at the beginning or along the processing. The esterification process (reaction) occurs under an inert atmosphere for 8h, and at 265 °C (Figure 2).

[0064] In an embodiment, rosin samples were analysed by gas chromatography coupled with mass spectrometry (GC-MS) to determine their chemical composition. Before analysis, the samples were derivatized by methylation using diazomethane. Briefly, approximately 20 mg of a rosin sample, containing 0.6 mg of tetracosane (internal standard), dissolved in diethyl ether with 10% (v / v) methanol were treated with diazomethane, prepared by the reaction between A / -Methyl- / V-(p-tolylsulfonyl)nitrosamide (Sigma-Aldrich, Sintra, Portugal) with an ethanolic solution of potassium hydroxide, using a tube-in-tube apparatus to avoid direct manipulation of diazomethane. After purging of the excess of diazomethane the solvent was evaporated, and the derivatized sample redissolved in 1 mL of dichloromethane to be analysed by GC-MS. The GC-MS system was equipped with a Trace Gas Chromatograph (2000 series) and a Thermo Scientific DSQ II mass spectrometer (Waltham, Massachusetts, USA). The chromatography column was a capillary column DB-1 J&W (30 m x 0.32 mm internal diameter, 0.25 pm thick, Santa Clara, California, USA) and the carrier gas helium (35 cms-1). The temperature program was as follows: initial temperature, 200 °C for 2 min; 5 °C min1to 215 °C for 2 min; 5 °C min1to 250 °C for 1 min. The injector and transfer line temperatures were 250 °C and 290 °C, respectively, and the split ratio was 1:80. The mass spectrometer was operated in electron impact mode with energy of 70 eV, and data were collected in a range of m / z 35 - 700. The ion source was maintained at 250 °C. The compounds were identified based on their mass spectra and fragmentation patterns. Calibration curves of abietic acid and dehydroabietic acid were used for quantitative analyses.

[0065] In an embodiment, Fourier transform infrared-attenuated total reflection (FTI R— ATR) spectra were collected with a PerkinElmer FT-IR System Spectrum BX spectrophotometer (PerkinElmer Inc., Waltham, MA, USA) equipped with a single horizontal Golden Gate ATR cell, over the range of 600-4000 cm-1, at a resolution of 4 cm-1, over 32 scans.

[0066] In an embodiment, the Gardner colour value was determined according to the standard procedure ASTM D1544-04 (2018). Briefly, the sample was diluted in analytical-grade toluene (50% w / w) and analysed using Lovibond PFX 195 colorimeter. The Gardner colour value scale establishes a gradation of yellowing from 1 to 18, with 1 being light yellow and 18 being dark brown. A low Gardner colour value (lighter colour) indicates higher purity and stability, which is preferred; a high Gardner colour value (darker colour) suggests higher oxidation, impurities, or thermal degradation, which can negatively affect the performance of rosin.

[0067] In an embodiment, the acid number was obtained according to the standard procedure ASTM D465-15 (2020). In brief, 1-3 g of sample was dissolved in 50 mL of toluene and 20 mL of isopropanol, then 2-3 drops of phenolphthalein were added. The solution was titrated with a standard solution of 0.1 M ethanolic KOH. The acid number is expressed in mg of KOH required to neutralize 1 g of sample. When working with rosin, it is important to assure an acid number between 110 to 160 mg KOH g1to allow its processing. On the other hand, when working with rosin esters, low acid values 5 to 20 mg KOH g1mean better stability, lower reactivity, and improved compatibility in formulations like hot-melt adhesives, inks, and coatings.

[0068] In an embodiment, the softening point was determined according to the standard procedure ASTM E28-18 (2022) using a Ring-and-Ball apparatus. This apparatus consists of a metal ring filled with the solidified sample. An iron ball is put above this ring and the apparatus is placed on a support and submerged in glycerol, which is slowly heated. The result obtained refers to the temperature, in °C, at which the iron ball touches the base of the support.

[0069] All the experiments were performed at least in triplicate, and the obtained results were expressed as means with associated standard deviation.

[0070] The present disclosure is more particularly described in the following examples that are intended as illustrative only, since numerous modifications and variations are possible and will be apparent to those skilled in the art.

[0071] Example 1 - Example comprising the addition of 0.3% (wtocopheroi / wrosin) of alpha-tocopherol during thermal processing of rosin at 265 °C under nitrogen atmosphere

[0072] Approximately 0.3 g of alpha-tocopherol were added to 100.0 g of gum rosin in a round-bottom flask under nitrogen atmosphere. The mixture was heated to 265 °C for 8 h, with stirring. Gardner colour, acid number and softening point values were determined at the end of the thermal processing and compared to the values obtained using the synthetic antioxidant Lowinox TBM-6 using the same experimental conditions (Table 1). GC-MS analysis was performed at the end of the processing to confirm the chemical composition of rosin, which was also compared to that of initial rosin and rosin processed using the synthetic antioxidant Lowinox TBM-6 (Figure 4).

[0073] Table 1. Results of the Gardner colour, acid number and softening point values after thermal processing of rosin using alpha-tocopherol and Lowinox TBM-6, from Example 1.Softening Point Acid Number Antioxidant Gardner colour(°C) (mg KOH g’1) alpha-Tocopherol 6.6 ± 0.1 85.0 ±4.2 141.3 ± 2.1 Lowinox TBM-6 6.4 ± 0.5 84.8 ± 0.4 130.9 ± 0.1*Data are presented as mean ± standard deviation (SD).

[0074] When using alpha-tocopherol, similar values of Gardner colour, acid number, and softening point can be obtained when compared to Lowinox TBM-6 during the thermal processing of rosin. Similar chemical composition can be obtained using alphatocopherol and Lowinox TBM-6 after thermal processing of rosin (Figure 4).

[0075] Example 2 - Example comprising the addition of 0.3% (wthymoi / wrosin) of thymol during thermal processing of rosin at 265 °C under nitrogen atmosphere

[0076] Approximately 0.3 g of thymol were added to 100.0 g of gum rosin in a roundbottom flask under nitrogen atmosphere. The mixture was heated to 265 °C for 8 h. Gardner colour, acid number and softening point values were determined at the end of the thermal processing and compared to the values obtained using the synthetic antioxidant Lowinox TBM-6 using the same experimental conditions (Table 2). GC-MS analysis was performed in the end of the processing to confirm the chemical composition of rosin, which was also compared to that of initial rosin and rosin processed using the synthetic antioxidant Lowinox TBM-6 (Figure 4).

[0077] Table 2. Results of the Gardner colour, acid number and softening point values after thermal processing of rosin using thymol and Lowinox TBM-6, from Example 2.Softening Point Acid Number Antioxidant Gardner colour(°C) (mg KOH g’1) Thymol 6.2 ± 0.1 86.8 ± 1.1 130.9 ± 0.6 Lowinox TBM-6 6.4 ± 0.5 84.8 ± 0.4 130.9 ± 0.1*Data are presented as mean ± standard deviation (SD).

[0078] When usingthymol, similar values of Gardner colour, acid number, and softening point can be obtained when compared to Lowinox TBM-6 during the thermal processing of rosin. Similar chemical composition can be obtained using thymol and Lowinox TBM-6 after thermal processing of rosin (Figure 4).

[0079] Example 3 - Example comprising the addition of 0.3% (waiPha-tocopheroi / wrosin) of alpha-tocopherol and 0.3% (wjOdine / wrosin) of iodine during thermal processing of rosin at 265 °C under nitrogen atmosphere

[0080] Approximately 0.3 g of alpha-tocopherol and 0.3 g of iodine were added to 100.0 g of gum rosin in a round-bottom flask under nitrogen atmosphere. The mixture washeated to 265 °C for 8 h. Gardner colour, acid number and softening point values were determined in the end of the thermal processing and compared to the values obtained using the synthetic antioxidant Lowinox TBM-6 using the same experimental conditions (Table 3). GC-MS analysis was performed at the end of the processing to confirm the chemical composition of rosin, which was also compared to that of initial rosin and rosin processed using the synthetic antioxidant Lowinox TBM-6 (Figure 4).

[0081] Table 3. Results of the Gardner colour, acid number and softening point values after thermal processing of rosin using alpha-tocopherol and iodine, and Lowinox TBM-6, from Example 3.Softening Point Acid Number Antioxidant Gardner colour(°C) (mg KOH g’1) alpha-Tocopherol + iodine 5.7 ± 0.5 79.3 ± 3.9 144.3 ± 0.2 Lowinox TBM-6 6.4 ± 0.5 84.8 ± 0.4 130.9 ± 0.1*Data are presented as mean ± standard deviation (SD).

[0082] When using alpha-tocopherol with iodine, similar values of Gardner colour, and improved softening point and acid number can be obtained when compared to Lowinox TBM-6 during the thermal processing of rosin. Surprisingly, the percentage of abietic acid in samples processed with the addition of alpha-tocopherol and iodine is lowerthan in samples treated with Lowinox TBM-6. Also, the percentage of dehydroabietic acid, together with non-conjugated abietic and pimaric acid derivatives (identified all together in Figure 3, Figure 4 and Table 4 as "other resin acid isomers) is higher in samples processed with the addition of alpha-tocopherol and iodine, which is indicative of increased stability.

[0083] Table 4. Embodiment of chemical composition (%) of raw rosin and rosin after thermal processing at 265 °C for 8 h with alpha-tocopherol, thymol, with or without iodine, under inert atmosphere; or LowinoxTBM-6 (comparative data).Other Resin Decarboxylated Pimaric Sandaracopimaric Isopimaric Palustric Dihydroabietic Abietic NeoabieticSample Acids Isomers isomets Acid (%) Acid (%) Acid (%) Acid (%) Acid (%) Acid (%) Acid (%)(%) (%) Raw Rosin 4.4 ± 0.3 1.4 ± 0.2 14.1 ± 0.7 11.1 ± 0.3 4.0 ± 0.2 50.4 ± 1.1 12.8 ± 0.2 1.9 ± 0.0 0.0 ± 0.4 Alpha-Tocopherol 1.6 ± 0.2 1.6 ± 0.0 6.4 ± 0.1 11.4 ± 0.0 21.7 ± 0.4 31.5 ± 0.5 4.0 ± 0.0 2.7 ± 1.3 0.4 ± 0.0 Thymol 1.7 ± 0.2 1.5 ± 0.1 8.3 ± 0.6 12.0 ± 0.7 21.1 ± 2.3 30.4 ± 3.3 3.5 ± 0.2 1.0 ± 8.0 0.5 ± 0.0 Lowinox TBM-6 2.4 ± 0.0 1.8 ± 0.0 8.9 ± 0.1 11.3 ± 0.8 22.7 ± 0.8 31.0 ± 1.7 3.6 ± 0.2 9.7 ± 3.8 0.4 ± 0.0 alpha-Tocopherol1.1 ± 0.1 1.3 ± 0.0 1.3 ± 0.1 9.9 ± 0.4 24.9 ± 0.2 26.0 ± 0.7 2.9 ± 0.0 4.3 ± 1.0 0.8 ± 0.0 + iodineThymol + iodine 0.6 ± 0.1 1.1 ± 0.1 1.2 ± 0.1 9.5 ± 0.2 25.4 ± 0.1 24.3 ± 0.1 2.6 ± 0.1 6.8 ± 0.4 0.7 ± 0.0

[0084] Example 4 - Example comprising the addition of 0.3% (wthymoi / wrosin) of thymol and 0.3% (wiodine / wrOsin) of iodine during thermal processing of rosin at 265 °C under nitrogen atmosphere

[0085] Approximately 0.3 g of thymol and 0.3 g of iodine were added to 100.0 g of gum rosin in a round-bottom flask under nitrogen atmosphere. The mixture was heated to 265 °C for 8 h. Gardner colour, acid number and softening point values were determined in the end of the thermal processing and compared to the values obtained using the synthetic antioxidant Lowinox TBM-6 using the same experimental conditions (Table 5). GC-MS analysis was performed in the end of the processing to confirm the chemical composition of rosin, which was also compared to that of initial rosin and rosin processed using the synthetic antioxidant Lowinox TBM-6 (Figure 4).

[0086] Table 5. Results of the Gardner colour, acid number and softening point values after thermal processing of rosin using thymol and iodine, and Lowinox TBM-6, from Example 4.Acid Number Antioxidant Gardner colour Softening Point (°C)(mg KOH g’1) Thymol + iodine 5.4 ± 0.1 74.8 ± 1.1 149.9 ± 0.6 Lowinox TBM-6 6.4 ± 0.5 84.8 ± 0.4 130.9 ± 0.1*Data are presented as mean ± standard deviation (SD).

[0087] When using thymol with iodine, improved values of Gardner colour, softening point, and acid number can be obtained when compared to Lowinox TBM-6 during the thermal processing of rosin. Surprisingly, the percentage of abietic acid in samples processed with the addition of alpha-tocopherol and iodine is lower than in samples treated with Lowinox TBM-6. Also, the percentage of dehydroabietic acid, together with non-conjugated abietic and pimaric acid derivatives (identified all together in Figure 3, Figure 4 and Table 4 as "other resin acid isomers) is higher in samples processed with the addition of alpha-tocopherol and iodine, which is indicative of increased stability.

[0088] Example 5 - Example comprising the addition of 0.3% (waiPha-tocopheroi / wrosin) of alpha-tocopherol and 0.3% (wjOdine / wrosin) of iodine in the beginning of rosin esterification with glycerol under nitrogen atmosphere

[0089] Approximately 0.3 g of alpha-tocopherol and 0.3 g of iodine were added to 100.0 g of gum rosin in a round-bottom flask under nitrogen atmosphere. The mixture was heated to 160 °C to allow the melting of rosin. Then, 11.1 g of glycerol was added and temperature increased until 265 °C for 8 h to promote the esterification. Gardner colour, acid number and softening point values were determined in the end of the esterification and compared to the values obtained using the synthetic antioxidant Lowinox TBM-6 using the same experimental conditions (Table 6). FTIR-ATR spectroscopic analysis was performed in the end of the processing to confirm the extent of the esterification, which was also compared to that of initial rosin and rosin processed using the synthetic antioxidant Lowinox TBM-6.

[0090] Table 6. Results of the Gardner colour, acid number and softening point values after rosin esterification using alpha-tocopherol and iodine, and Lowinox TBM-6, from Example 5.Gardner Softening Point Acid Number Antioxidantcolour (°C) (mg KOH g’1) alpha-Tocopherol + iodine 5.4 ± 0.4 87.01 1.4 10.310.6 Lowinox TBM-6 5.510.2 86.212.8 11.11 1.1*Data are presented as mean 1 standard deviation (SD).

[0091] When using alpha-tocopherol with iodine, similar values of Gardner colour, softening point, and acid number can be obtained when compared to Lowinox TBM-6 during rosin esterification. Moreover, FTIR-ATR spectra confirmed the successfully esterification.

[0092] Example 6 - Example comprising the addition of 0.3% (waiPha-tocopheroi / wrosin) of alpha-tocopherol in the beginning of rosin esterification and 0.3% (wiodine / wrOsin) of iodine after 6 hours of rosin esterification with glycerol under nitrogen atmosphere

[0093] Approximately 0.3 g of alpha-tocopherol were added to 100.0 g of gum rosin in a round-bottom flask under nitrogen atmosphere. The mixture was heated to 160 °C to allow the melting of rosin. Then, 11.1g of glycerol was added and temperature increased until 265 °C to allow the esterification. After 6h, 0.3 g of iodine was added to the reaction, which was stirred for another 2 hours under nitrogen atmosphere. Gardner colour, acid number and softening point values were determined in the end ofesterification and compared to the values obtained using the synthetic antioxidant Lowinox TBM-6 using the same experimental conditions (Table 7). FTIR-ATR spectroscopic analysis was performed in the end of the processing to confirm the extent of the esterification, which was also compared to that of initial rosin and rosin processed using the synthetic antioxidant Lowinox TBM-6.

[0094] Table 7. Results of the Gardner colour, acid number and softening point values after rosin esterification using alpha-tocopherol and iodine, and Lowinox TBM-6, from Example 6.Gardner Softening Point Acid Number Antioxidantcolour (°C) (mg KOH g’1) alpha-Tocopherol + iodine 5.712.3 89.8 ± 1.2 10.710.6 Lowinox TBM-6 5.5 ± 0.2 86.512.8 11.11 1.1*Data are presented as mean 1 standard deviation (SD).

[0095] When using alpha-tocopherol with iodine, similar values of Gardner colour, softening point, and acid number can be obtained when compared to Lowinox TBM-6 during rosin esterification. Moreover, FTIR-ATR spectra confirmed the successfully esterification.

[0096] Example 7 - Example comprising the addition of 0.3% (waiPha-tocopheroi / wrosin) of alpha-tocopherol in the beginning of rosin esterification and 0.3% (wiodine / wrOsin) of iodine after 2 hours of rosin esterification with glycerol under nitrogen atmosphere

[0097] Approximately 0.3 g of alpha-tocopherol were added to 100.0 g of gum rosin in a round-bottom flask under nitrogen atmosphere. The mixture was heated to 160 °C to allow the melting of rosin. Then, 11.1g of glycerol was added and temperature increased until 265 °C to allow the esterification. After 2h, 0.3 g of iodine was added to the reaction, which was stirred for another 6 hours under nitrogen atmosphere. Gardner colour, acid number and softening point values were determined in the end of the esterification and compared to the values obtained using the synthetic antioxidant Lowinox TBM-6 using the same experimental conditions (Table 8). FTIR-ATR spectroscopic analysis was performed in the end of the processing to confirm the extent of the esterification, which was also compared to that of initial rosin and rosin processed using the synthetic antioxidant Lowinox TBM-6.

[0098] Table 8. Results of the Gardner colour, acid number and softening point values after rosin esterification using alpha-tocopherol and iodine, and Lowinox TBM-6, from Example 7.Gardner Softening Point Acid Number Antioxidantcolour (°C) (mg KOH g’1) alpha-Tocopherol + iodine 5.9 ± 0.6 82.510.1 12.910.1 Lowinox TBM-6 5.5 ± 2 86.512.8 11.11 1.1*Data are presented as mean 1 standard deviation (SD).

[0099] When using alpha-tocopherol with iodine, similar values of Gardner colour, acid number, and softening point can be obtained when compared to Lowinox TBM-6 during rosin esterification. Moreover, FTIR-ATR spectra confirmed the successfully esterification.

[0100] Example 8 - Example comprising the addition of 0.3% (wthymoi / wrosin) of thymol and 0.3% (wiodine / wrOsin) of iodine in the beginning of rosin esterification with glycerol under nitrogen atmosphere

[0101] Approximately 0.3 g of thymol and 0.3 g of iodine were added to 100.0 g of gum rosin in a round-bottom flask under nitrogen atmosphere. The mixture was heated to 160 °C to allow the melting of rosin. Then, 11.1 g of glycerol was added and temperature increased until 265 °C for 8 h to allow the esterification. Gardner colour, acid number and softening point values were determined at the end of the esterification and compared to the values obtained using the synthetic antioxidant Lowinox TBM-6 using the same experimental conditions (Table 9). FTIR-ATR spectroscopic analysis was performed in the end of the processing to confirm the extent of the esterification, which was also compared to that of initial rosin and rosin processed using the synthetic antioxidant Lowinox TBM-6.

[0102] Table 9. Results of the Gardner colour, acid number and softening point values after rosin esterification using thymol and iodine, and Lowinox TBM-6, from Example 8.Gardner Softening Point Acid Number Antioxidantcolour (°C) (mg KOH g’1) Thymol + iodine 4.8 ± 0.8 89.810.7 18.610.8 Lowinox TBM-6 5.510.2 86.512.8 11.11 1.1*Data are presented as mean 1 standard deviation (SD).

[0103] When using thymol with iodine, improved values of Gardner colour, softening point, and acid number can be obtained when compared to Lowinox TBM-6 during rosin esterification. Moreover, FTIR-ATR spectra confirmed the successfully esterification.Example 9 - Example comprising the addition of 0.3% (wthymoi / wrosin) of thymol in the beginning of rosin esterification and 0.3% (wiodine / wrOsin) of iodine after 6 h of rosin esterification with glycerol under nitrogen atmosphere

[0104] Approximately 0.3 g of thymol were added to 100.0 g of gum rosin in a round-bottom flask under nitrogen atmosphere. The mixture was heated to 160 °C to allow the melting of rosin. Then, 11.1g of glycerol was added and temperature increased until 265 °C to allow the esterification. After 6 h, 0.3 g of iodine was added to the reaction, which was stirred for another 2h under nitrogen atmosphere. Gardner colour, acid number and softening point values were determined in the end of esterification and compared to the values obtained using the synthetic antioxidant Lowinox TBM-6 using the same experimental conditions (Table 10). FTIR-ATR spectroscopic analysis was performed in the end of the processing to confirm the extent of the esterification, which was also compared to that of initial rosin and rosin processed using the synthetic antioxidant Lowinox TBM-6.

[0105] Table 10. Results of the Gardner colour, acid number and softening point values after rosin esterification using thymol and iodine, and Lowinox TBM-6, from Example 9.Softening Point Acid Number Antioxidant Gardner colour(2C) (mg KOH g’1) Thymol + iodine 6.0 ± 0.1 93.510.4 14.711.1 Lowinox TBM-6 5.510.2 86.512.8 11.111.1*Data are presented as mean 1 standard deviation (SD).

[0106] When using thymol with iodine, similar values of Gardner colour, softening point, and acid number can be obtained when compared to Lowinox TBM-6 during rosin esterification. Moreover, FTIR-ATR spectra confirmed the successfully esterification.

[0107] Example 10 - Example comprising the addition of 0.3% (wthymoi / wrosin) of thymol in the beginning of rosin esterification and 0.3% (wiodine / wrOsin) of iodine after 2 hours of rosin esterification with glycerol under nitrogen atmosphere

[0108] Approximately 0.3 g of thymol were added to 100.0 g of gum rosin in a round-bottom flask under nitrogen atmosphere. The mixture was heated to 160 °C to allow the melting of rosin. Then, 11.1g of glycerol was added and temperature increased until 265 °C to allow the esterification. After 2h, 0.3 g of iodine was added to the reaction, which was stirred for another 6 h under nitrogen atmosphere. Gardner colour, acid number and softening point values were determined in the end of the esterification and compared to the values obtained using the synthetic antioxidant Lowinox TBM-6 using the same experimental conditions (Table 11). FTIR-ATR spectroscopic analysis was performed at the end of the processing to confirm the extent of the esterification, which was also compared to that of initial rosin and rosin processed using the synthetic antioxidant Lowinox TBM-6.

[0109] Table 11. Results of the Gardner colour, acid number and softening point values after rosin esterification using thymol and iodine, and Lowinox TBM-6, from Example 10.Gardner Softening Point Acid Number Antioxidantcolour (°C) (mg KOH g’1) Thymol + iodine 5.4 ± 0.4 86.010.1 18.010.1 Lowinox TBM-6 5.5 ± 0.2 86.512.8 11.11 1.1*Data are presented as mean 1 standard deviation (SD).

[0110] When using thymol with iodine, similar values of Gardner colour, acid number, and softening point can be obtained when compared to Lowinox TBM-6 during rosin esterification. Moreover, FTIR-ATR spectra confirmed the successfully esterification.

[0111] Example 11 - Example comprising the addition of 0.3% (wthymoi / wrosin) of thymol and 0.15% (wiodine / wrOsin) of iodine in the beginning of rosin esterification with glycerol under nitrogen atmosphere

[0112] Approximately 7.5 g of thymol and 3.75 g of iodine were added to 2500.0 g of gum rosin in a round-bottom flask under nitrogen atmosphere. The mixture was heated to 160 °C to allow the melting of rosin. Then, 250.0 g of glycerol was added and temperature increased until 270 °C for 8 h to allow the esterification. Gardner colour, acid number and softening point values were determined in the end of the esterification and compared to the values obtained using the synthetic antioxidant Lowinox TBM-6 using the same experimental conditions (Table 12). FTIR-ATR spectroscopic analysis was performed in the end of the processing to confirm the extent of the esterification, which was also compared to that of initial rosin and rosin processed using the synthetic antioxidant Lowinox TBM-6.

[0113] Table 12. Results of the Gardner colour, acid number and softening point values after rosin esterification using thymol and iodine, and Lowinox TBM-6, from Example 11.Gardner Softening Point Acid Number Antioxidantcolour (°C) (mg KOH g’1) Thymol + iodine 5.0 ± 0.0 87 ± 0.1 10.710.1 Lowinox TBM-6 5.5 ± 0.2 86.5 ± 2.8 11.111.1*Data are presented as mean 1 standard deviation (SD).

[0114] When using thymol with iodine, improved values of Gardner colour, softening point, and acid number can be obtained when compared to Lowinox TBM-6 during rosin esterification. Moreover, FTIR-ATR spectra confirmed the successfully esterification.

[0115] Example 12 - Example comprising the addition of 0.3% (waiPha-tocopheroi / wrosin) of al pha-tocopherol and 0.15% (wjOdine / wrosin) of iodine in the beginning of rosin esterification with glycerol under nitrogen atmosphere

[0116] Approximately 7.5 g of alpha-tocopherol and 3.75 g of iodine were added to 2500.0 g of gum rosin in a round-bottom flask under nitrogen atmosphere. The mixture was heated to 160 °C to allow the melting of rosin. Then, 250.0 g of glycerol was added and temperature increased until 270 °C for 12 h to allow the esterification. Gardner colour, acid number and softening point values were determined in the end of the esterification and compared to the values obtained using the synthetic antioxidant Lowinox TBM-6 using the same experimental conditions (Table 13). FTIR-ATR spectroscopic analysis was performed in the end of the processing to confirm the extent of the esterification, which was also compared to that of initial rosin and rosin processed using the synthetic antioxidant Lowinox TBM-6.

[0117] Table 13. Results of the Gardner colour, acid number and softening point values after rosin esterification using alpha-tocopherol and iodine, and Lowinox TBM-6, from Example 12.Gardner Softening Acid Number Antioxidantcolour Point (°C) (mg KOH g1) alpha-Tocopherol + iodine 4.6 ± 0.1 97 ± 0.1 25.8 ± 0.2 Lowinox TBM-6 5.5 ± 0.2 86.5 ± 2.8 11.1 ± 1.1*Data are presented as mean ± standard deviation (SD).

[0118] When using alpha-tocopherol with iodine, improved values of Gardner colour, softening point, and acid number can be obtained when compared to Lowinox TBM-6 during rosin esterification. Moreover, FTIR-ATR spectra confirmed the successfully esterification.

[0119] Example 13 - Example comprising the addition of 0.15% (waiPha-tocopheroi / wrosin) of al pha-tocopherol and 0.05% (wjOdine / wrosin) of iodine in the beginning of rosin esterification with glycerol under nitrogen atmosphere

[0120] Approximately 3.75 g of alpha-tocopherol and 1.3 g of iodine were added to 2500.0 g of gum rosin in a round-bottom flask under nitrogen atmosphere. The mixture was heated to 160 °C to allow the melting of rosin. Then, 275.0 g of glycerol was added and temperature increased until 275 °C for 8 h to allow the esterification. Gardner colour, acid number and softening point values were determined in the end of the esterification and compared to the values obtained using the synthetic antioxidant Lowinox TBM-6 using the same experimental conditions (Table 14). FTIR-ATR spectroscopic analysis was performed in the end of the processing to confirm the extent of the esterification, which was also compared to that of initial rosin and rosin processed using the synthetic antioxidant Lowinox TBM-6.

[0121] Table 14. Results of the Gardner colour, acid number and softening point values after rosin esterification using alpha-tocopherol and iodine, and Lowinox TBM-6, from Example 13.Gardner Softening Point Acid Number Antioxidantcolour (°C) (mg KOH g’1) alpha-Tocopherol + iodine 4.7 ± 0.0 96.5 ± 0.1 11.3 ± 0.0 Lowinox TBM-6 5.5 ± 0.2 86.5 ± 2.8 11.1 ± 1.1*Data are presented as mean ± standard deviation (SD).

[0122] When using alpha-tocopherol with iodine, improved values of Gardner colour, softening point, and acid number can be obtained when compared to Lowinox TBM-6 during rosin esterification. Moreover, FTIR-ATR spectra confirmed the successfully esterification.

[0123] Example 14 - Example comprising the addition of 0.3% ( wgaiiic acid / Wrosin) of gallic acid during thermal processing of rosin at 265 °C under nitrogen atmosphere (Comparative data)

[0124] Approximately 0.3 g of gallic acid were added to 100.0 g of gum rosin in a round-bottom flask under nitrogen atmosphere. The mixture was heated to 265 °C for 8 h, with stirring. Gardner colour, acid number and softening point values were determined at the end of the thermal processing and compared to the values obtained using the synthetic antioxidant Lowinox TBM-6 using the same experimental conditions (Table 15).

[0125] Table 15. Results of the Gardner colour, acid number and softening point values after thermal processing of rosin using gallic acid and Lowinox TBM-6, from Example 14.Softening Point Acid Number Antioxidant Gardner colour(°C) (mg KOH g’1) Gallic acid 8.5 ± 0.1 80.0 ± 0.2 157.1 ± 0.4 Lowinox TBM-6 6.4 ± 0.5 84.8 ± 0.4 130.9 ± 0.1*Data are presented as mean ± standard deviation (SD).

[0126] When using gallic acid, worsen values of Gardner colour, acid number, and softening point can be obtained when compared to Lowinox TBM-6 during the thermal processing of rosin.

[0127] Example 15 - Example comprising the addition of 0.3% (wcaffeic acid / Wrosin) of caffeic acid during thermal processing of rosin at 265 °C under nitrogen atmosphere (Comparative data)

[0128] Approximately 0.3 g of caffeic acid were added to 100.0 g of gum rosin in a round-bottom flask under nitrogen atmosphere. The mixture was heated to 265 °C for 8 h, with stirring. Gardner colour, acid number and softening point values were determined at the end of the thermal processing and compared to the values obtained using the synthetic antioxidant Lowinox TBM-6 using the same experimental conditions (Table 16).

[0129] Table 16. Results of the Gardner colour, acid number and softening point values after thermal processing of rosin using caffeic acid and Lowinox TBM-6, from Example 15.Softening Point Acid Number Antioxidant Gardner colour(°C) (mg KOH g’1) Caffeic acid 9.2 ± 0.9 86.510.3 147.110.7 Lowinox TBM-6 6.410.5 84.810.4 130.910.1*Data are presented as mean 1 standard deviation (SD).

[0130] When using caffeic acid, worsen values of Gardner colour, acid number, and softening point can be obtained when compared to Lowinox TBM-6 during the thermal processing of rosin.

[0131] The term "comprising" whenever used in this document is intended to indicate the presence of stated features, integers, steps, components, but not to preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

[0132] The disclosure should not be seen in any way restricted to the embodiments described and a person with ordinary skill in the art will foresee manypossibilities to modifications thereof. The above-described embodiments are combinable.

[0133] The following dependent claims further set out particular embodiments of the disclosure.REFERENCES1] Zinkel DF, Russell J. Naval stores : production, chemistry, utilization. New York: Pulp Chemical Assn; 1989.[2] Stoia M, Oancea S. Low-Molecular-Weight Synthetic Antioxidants: Classification, Pharmacological Profile, Effectiveness and Trends. Antioxidants 2022;ll:638. https: / / doi.org / 10.3390 / antioxll040638.[3] Wang S. Synthesis of light-colored rosin glycerol ester. Holzforschung 2007;61:499-503. https: / / doi.org / 10.1515 / HF.2007.103.[4] Mota RFG, Bordado JCM, Goncalves JFD. Increase of rosin ester shelf life: Improvement of oxidative stability. 2016.[5] Frihart Charles R, Krajca Kenneth E, Neumann Brett A. Light-colored, low molecular weight phenolic-modified rosin esters. WO 2000 / 017280 Al, 2000.[6] Harrison Stuart A. Phosphite esters as esterification catalysts. US 2729660 A, 1956.[7] Wheelus Charles Glenn. ROSIN COMPOUNDS OF IMPROVED COLOR AND STABILITY. US3423389A, 1969.[8] Lange Jos H M, Schaapman Mark C, Hine Justyna J. COMPOSITIONS CONTAINING ROSIN ESTER AND ETHYLENE POLYMERS. WO 2016 / 154456 Al, 2016.[9] Spivack John D. Metal derivatives of dialkylhydroxy-phenylalkylphosphonic acids and phosphonic acid half-esters. US 3310575 A, 1967.

[0010] Dallavia Anthony J. Rosin Ester with Low Color and Process for Preparing Same. US 2011 / 0034669 Al, 2011.

[0011] Kutsek George Joseph. Inhibition of rosin crystallization. US6939944B2, 2005.

[0012] Li Guiqing, Guan Jihua, Lu Shunzhong, Qiu Mi, Tang Xingyue, Yang Suhua, et al. Water-white thermostable rosin resin and preparation method thereof. CN112322189A, 2021.

Claims

C L A I M S1. Method for obtaining a processed rosin, the method comprising the following steps:obtaining a gum rosin;adding 0.01% to 5.0% (wantioxidant / wrOsin) of a natural antioxidant to the gum rosin to obtain a mixture, provided the natural antioxidant is not gallic acid, caffeic acid or oxalic acid;stirring the mixture at a temperature ranging from 80 °C to 300 °C, for 5 h to 20 h, to obtain a processed rosin;wherein the processed rosin is free of synthetic organic antioxidants, or products thereof.

2. The method according to the previous claim, wherein the concentration of the natural antioxidant ranges from 0.1% to 0.5% (wantioxidant / wrasin), preferably from 0.15% tO 0.3% (Wantioxidant / Wrosin).

3. The method according to any of the previous claims, wherein the natural antioxidant is selected from a list comprising phenolic compounds, vitamins, carotenoids, and mixtures thereof.

4. The method according to any of the previous claims, wherein the phenolic compound is selected from a list comprising quercetin, resveratrol, curcumin, tannins, ellagic acid, ferulic acid, thymol, eugenol, vanillin, carvacrol, kaempferol, apigenin, luteolin, chlorogenic acid, cinnamic acid, rosmarinic acid, epicatechin, rutin, hesperidin, naringenin, p-coumaric acid, sesamol, catechin derivatives, and mixtures thereof.

5. The method according to any of the previous claims, wherein the vitamin is selected from a list comprising ascorbic acid, tocopherols, tocotrienols, retinol, phylloquinone, menaquinones, and mixtures thereof.

6. The method according to any of the previous claims, wherein the carotenoid is selected from beta-carotene, lycopene, lutein, zeaxanthin, astaxanthin, and mixtures thereof.

7. The method according to any of the previous claims, wherein the natural antioxidant is alpha-tocopherol, thymol or mixtures thereof.

8. The method according to any of the previous claims, further comprising the step of adding 5% to 15% (wpoiyoi / wrosin) of a polyol to the mixture of gum rosin and natural antioxidant.

9. The method according to the previous claim, wherein the polyol is selected from a list comprising glycerol, pentaerythritol, and mixtures thereof.

10. The method according to any of the previous claims, wherein iodine is added to the mixture comprising gum rosin and natural antioxidant.

11. The method according to the previous claim, wherein the concentration of iodine ranges from 0.01% to 5.0% (wiOdine / wrosin), preferably 0.1% to 0.3% (wiOdine / wrosin).

12. The method according to any of the previous claims, wherein the method is carried out in an inert atmosphere, preferably nitrogen atmosphere.

13. The method according to any of the previous claims, wherein the mixture is stirred at a temperature ranging from 160 °C to 270 °C.

14. The method according to the previous claim, wherein the mixture is stirred at a temperature ranging from200 °C to 265 °C.

15. The method according to any of the previous claims, wherein the mixture is stirred for 8 h to 10 h, preferably 8 h.

16. The method according to any of the previous claims, wherein the gum rosin has a Gardner colour value ranging from 3 to 10, softening point ranging from 65 to 95 °C, and acid number ranging from 120 to 190 mg KOH g1.

17. The method according to any of the previous claims, wherein the gum rosin has a Gardner colour value of 8.5, softening point of 76.5 °C, and acid value of 172.6 mg KOH g1.

18. A processed rosin obtainable by a method as described in any of the previous claims, wherein the processed rosin is free of synthetic organic antioxidants, or products thereof .

19. The processed rosin according to the previous claim, wherein the rosin has a Gardner colour value ranging from 4 to 9, a softening point ranging from 70 to 95 °C, and an acid number ranging from 110 to 160 mg KOH g1.

20. The processed rosin according to the previous claim, wherein the rosin is a rosin ester and has a Gardner colour value ranging from 2 to 8, a softening point ranging from 75 to 125 °C, and an acid number ranging from 5 to 35 mg KOH g1.

21. Use of a processed rosin as described in any of the previous claims 18-20, as a tackifier, binding agent, viscosity controller, pigment coating, or cross-linking agent.

22. Article comprising the processed rosin according to any of the previous claims, 18- 21.

23. The article according to the previous claim, wherein the article is a cosmetic product, a depilatory wax, an adhesive, a printing ink, a chewing gum, a band aid, a paper, a pharmaceutical composition, a road-marking paint, a paint, a water-based adhesive, a hotmelt adhesive, a glue, a solvent-based adhesive, a varnish, or an animal nutrition product.

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