MODIFYING COMPOSITION, A COMPOSITION, METHOD FOR OBTAINING A COMPOSITION, USE OF A MODIFYING COMPOSITION AND USE

Description

1 / 18 “MODIFYING COMPOSITION, A COMPOSITION, METHOD FOR OBTAINING A COMPOSITION, USE OF A MODIFYING COMPOSITION AND USE” DESCRIPTIVE MEMORY BACKGROUND OF THE INVENTION

[0001] Polymer matrices are a group of synthetic polymers with multiple applications today. Broadly speaking, they can be divided into thermoplastic and thermosetting polymers. Thermosetting polymers include epoxy, polyurethane, acrylic, and phenolic resins, among others, while thermoplastics include PLA, nylon, ABS, polycarbonates, polyethylene (PE, HDPE, LDPE), polypropylene (PP), polyethylene terephthalate (PET), and many others with diverse industrial and domestic applications.

[0002] Despite their immense usefulness, polymeric matrices lack some properties that can be very convenient in many of their applications. For example, in the case of polymeric resins, it is highly desirable that the paints or varnishes have anti-corrosive and / or biocidal properties, in order to extend the lifespan of the object coated with the resin. In many cases, the fact that the resin hardens upon drying is also a very desirable characteristic.

[0003] The same applies to various plastics, where it is desirable that the polymeric material protects metals in contact with it against corrosion or has biocidal properties that prevent the formation of biofilm on the material, or simply that, through a biocidal effect, it keeps objects or surfaces sanitized.

[0004] The inventors developed an additive composition for polymer matrices that gives them anti-corrosive and biocidal properties and improves their mechanical capabilities. Petition 870250090833, dated 06 / 10 / 2025, page 47 / 73 2 / 18

[0005] Corrosion is the spontaneous chemical and / or electrochemical process by which metallic materials deteriorate upon contact with a corrosive environment (air, moisture, soil, vapors, etc.), due to the unstable nature of metallic elements. The deterioration of metallic structures due to corrosion entails environmental, direct and indirect economic, and safety costs for people, which have been estimated at approximately US$2.5 trillion annually, representing 3.4% of the world's gross domestic product, according to the IMPACT Study reported by NACE International. On the other hand, between 15 and 35% of these costs can be avoided through the management and implementation of corrosion control measures.

[0006] Control measures include the use of corrosion-resistant alloys, cathodic or anodic protection, and / or the use of organic and inorganic coatings, with the aim of hindering or preventing the anodic, cathodic, or both reactions. One of the most effective methods is the use of organic coatings or a coating scheme. Organic coatings consist mainly of pigments, rheological modifiers, functional additives, and a binder material, which corresponds to the polymeric matrix (acrylic, epoxy, polyurethane, polyurea, among others) responsible for generating a continuous film in which the additives are homogeneously distributed.

[0007] Among the additives are corrosion inhibitors, one of the main and most efficient used by the coatings industry being those based on chromates. These act by passivating the surface through the formation of compact and adherent oxides, producing the reduction of hexavalent to trivalent chromium species due to their oxidizing power. Their widespread use is due to their flexibility and versatility in inhibiting corrosion under various conditions (corrosive medium, pH, temperature, etc.), as well as their advantageous cost-benefit ratio. Despite their use Petition 870250090833, dated 06 / 10 / 2025, page 48 / 73 3 / 18 successful in coatings, the World Health Organization released a series of studies conducted worldwide by various independent entities since 1972 that showed a carcinogenic effect of chromium compounds. On the other hand, in 2006, a European regulation called REACH (Registration, Evaluation, Permit and Restriction of Chemicals) was created, which sets requirements for industries regarding the use of hazardous substances and their associated risks. Thus, the use of chromate in the coatings industry was prohibited, except for aeronautical and military applications, for which an exclusive authorization granted by the ECHA (European Chemicals Agency) is required. Similarly, lead-based inhibitors were also withdrawn from industrial use in coatings and paints due to their high toxicity.These restrictions have driven the search for new inhibitors that offer a compromise between good inhibitory performance, as well as low toxicity and low potential for environmental damage. As a replacement for these compounds, inorganic compounds such as phosphates, vanadates, molybdates, and silicates, which have lower inhibitory capacity, have been implemented and incorporated in higher percentages as part of anticorrosive formulations.

[0008] On the other hand, it is known that surfaces and inanimate objects can be contaminated and, under certain conditions, colonized by various microorganisms, such as pathogenic bacteria. It is desirable that materials in habitual contact with people or animals have biocidal properties that allow for maintaining a sanitized environment, with less likelihood of transmission of diseases caused by bacteria. Currently, external cleaning compositions are used as sanitizers, and some metallic nanoparticles with this effect have also been used in some materials, the most commonly used being copper and silver nanoparticles. Petition 870250090833, dated 06 / 10 / 2025, page 49 / 73 4 / 18

[0009] Finally, it is always desirable to improve the mechanical properties of polymer matrices, giving these materials greater durability in their function. For example, a paint exposed to wear from abrasion or erosion can lose its surface protection capacity due to material loss, which is a very common case in industrial applications or in components exposed to heavy traffic.

[0010] Therefore, each of these properties has been studied, and there are several technologies to address each of these challenges in improving polymer matrices. However, the invention addresses all these aspects together in a way not foreseen in the state of the art, by employing modified lignin in combination with a divalent or trivalent cation. STATE OF THE ART

[0011] Some technologies related to the present invention are detailed below: - Patent application WO2017 / 064499 (Dodds et al.) entitled “Corrosion inhibitor”. It protects the use of corrosion inhibitors based on azole organic compounds and, in particular, the use of benzotriazole to obtain the benzotriazolate ion through deprotonation, which is retained by an ion-exchange resin for its controlled release. The aromatic structure of benzotriazole, in which the five-membered ring has three nitrogens, exhibits a high affinity for the metallic surface, forming highly stable complexes that also promote the adhesion of polymeric coatings. This inhibitor acts primarily as a complement to the use of phosphates. This document does not anticipate the formulation of the invention; - Application US2795564A discloses aqueous paint bases and water-based paints and the process for preparing them, where sodium lignin sulfonate is used in the examples. The use of lignin in this case is for the dispersion of a water-based formulation, where lignin is used as Petition 870250090833, dated 06 / 10 / 2025, pp. 50 / 73 5 / 18 surfactant, which is not related to the application or properties of lignin exploited in our invention. Without limiting ourselves to theory, the use of divalent or trivalent cations instead of sodium modifies the properties of the composition of the invention, as can be seen in example 4 of the invention. Furthermore, it is not obvious that an additive used as a surfactant in an aqueous medium can be useful in a polymeric matrix, which is explained by the difference in its composition. The composition of the invention is not soluble in polar solvents, such as water; - Patent CN108587405A describes the formulation of a water-based zinc-rich coating incorporating Kraft lignin. In this case, the zinc is incorporated in a metallic state to act as a sacrificial material during corrosion. This type of coating is quite common in industry, generally used as a primer in paint schemes. In the case of lignin, it is used as part of the resin's curing agent and not as a functional additive within the formulation. That is, although patent CN108587405A includes elements similar to the formulation of the invention, it does not anticipate it.

[0012] This shows that, despite advances in non-toxic materials, there is still a need to develop more efficient, economically viable alternatives that are not harmful to health and the environment. This need is addressed and resolved by the present invention. BRIEF DESCRIPTION OF THE FIGURES

[0013] Figure 1: Scanning electron microscopy micrograph of a zinc organometallic compound.

[0014] Figure 2: Infrared spectrum of the lignin precursor and the organometallic zinc complex.

[0015] Figure 3: Raman spectrum of the organometallic zinc complex. Petition 870250090833, dated 06 / 10 / 2025, pp. 51 / 73 6 / 18

[0016] Figure 4: Photograph of panels exposed in a salt spray chamber for 336 hours, coated with a) Control Formulation b) LgZn-0.5 Formulation c) LgZn-1.0 Formulation

[0017] Figure 5: Bode plot for samples coated with the Control Formulation and LgZn-1.0. DESCRIPTION OF THE INVENTION

[0018] The present technology corresponds to a polymer matrix modifying composition, with anti-corrosive, biocidal and mechanical property improving properties.

[0019] Lignin is the second most abundant biopolymer after cellulose and is found mainly in plant structures, acting as an adhesive for fibers in plants and trees. However, despite its abundance and high industrial production (mainly as a byproduct of the cellulose production process), less than 2% of it is used for the manufacture of value-added products, being mainly used as fuel in recovery boilers, where black liquor is burned to generate energy. Its separation and extraction from cellulose is currently carried out through four different processes, two of which are based on the use of sulfur, Kraft lignin and lignosulfonate, and two others are sulfur-free processes, Organosolv Lignin and Alkaline Lignin. It is worth noting that, to date, there is no pure or native lignin available, since all extraction processes involve modifications to its molecular structure.Of these four types of lignin, lignosulfonate, which is completely soluble in water, cannot be used in the invention, but the other three, which are soluble in alkaline pH, can be used. We will briefly describe them below: - Kraft Lignin - KL: Obtained by depolymerizing lignin to extract cellulose and hemicellulose using NaOH and NaS at high pressure and temperature (>170 °C) through the digestion of wood chips. Petition 870250090833, dated 06 / 10 / 2025, pp. 52 / 73 7 / 18 (usually pine or eucalyptus). During digestion, lignin and hemicellulose are degraded into shorter chains due to nucleophilic attack by S2- ions. As a result, a black liquor solution with Kraft lignin content >15% is obtained at a pH of 13-14. The lignin structure is modified by the incorporation of HS groups, in addition to the abundant OH groups; The main properties of Kraft lignin are as follows: • Molecular weight: 200 - 20000 Da; • Partially soluble in water, soluble in alkaline solution; - Lignosulfonate - LS: It is obtained by a process similar to the Kraft process, using high temperatures and pressures, as well as S2- and HS ions, with the difference that this process is carried out at a pH between 1.5 and 5. During the process, a similar rupture of ether bonds occurs, generating HSO3-, which is also incorporated into the lignin structure, leaving terminations with sulfonate groups; Its main properties are: • Molecular weight: 15,000 - 60,000 Da; • Soluble in water; - Organosolv Lignin: This is obtained using organic solvents to solubilize the lignin. When using solvents such as acetone, methanol, ethanol, butanol, or formic acid, hydrolytic cleavage of the aryl-ether bonds occurs, thus solubilizing lignin fragments and maintaining greater purity compared to sulfur-based processes. The fragmented lignin is subsequently recovered by dilution with acidified water, producing lignin precipitation, which is then filtered and separated; Its main properties are: • Molecular weight: 2000 - 9000 Da; • Partially soluble in water, soluble in alkaline solution; Petition 870250090833, dated 06 / 10 / 2025, pp. 53 / 73 8 / 18 - Alkaline lignin or soda lignin: It is obtained from an alkaline solution of NaOH with the addition of anthraquinone. This process is commonly used for straw and other types of hardwood. During the process, condensation and degradation of lignin occur, so the size of the chains depends largely on the retention time; Its main properties are: • Molecular weight: 800 - 3000 Da; • Partially soluble in water, soluble in alkaline solution.

[0020] It is important to note that, regardless of the nature of the lignin, they all exhibit hygroscopic properties due to the presence of phenolic groups, which reduces the barrier effect of corrosion inhibitor pigments / additives by creating preferential channels for water diffusion through the film.

[0021] Thus, the invention relates more particularly to a polymer matrix modifying composition, comprising: - between 50 and 99% of an organic fraction whose molecular structure corresponds to modified lignin, chosen from organosolv lignin, Kraft lignin, soda lignin or one of their derivatives; and - between 1 and 40% of an inorganic fraction composed of one or more divalent or trivalent inorganic cations, such as: Ca, Mg, Zn, Fe, Al, Cu, Ni, Mo and / or Mn; - between 0 and 10% of formulation aids.

[0022] Among the formulation aids, glycols, acids and bases stand out, whose function in all of them is the solubilization of lignin by deprotonation, thus facilitating the formation of the organometallic compound of the invention's composition. In addition, other dispersing or stabilizing compounds may be used.

[0023] Advantageously, matrix-modifying composition Petition 870250090833, dated 06 / 10 / 2025, pp. 54 / 73 The 9 / 18 polymeric composition of the invention exhibits low toxicity to humans and low potential for contamination or damage to the environment, due to the plant origin of its major component and the inhibition of the leaching potential of cations, due to the chelating capacity of lignin and its derivatives. A bioassay was performed to evaluate the toxicity of the composition of the invention in the freshwater fish model Danio rerio, using the standard for determining the acute toxicity of wastewater on zebrafish eggs (Danio rerio). The results showed that the composition of the invention has a lethal concentration that causes mortality in more than 50% of the population exposed to the product for 48 hours, or LC50 48 h, of 223.7 ppm. This result is considered to be low acute toxicity.

[0024] In addition, the invention also relates to the method of obtaining the polymer matrix modifying composition, which comprises the following steps: a) provide a modified lignin solution in an alkaline medium at a concentration between 2 and 30% by weight; b) Keep at a temperature between 20 and 70°C with gentle stirring; c) add an organic salt with a divalent or trivalent cation by drop; d) Keep agitated for 1 to 24 hours; e) Separate the precipitate from the solvent and wash; f) Dry in an oven at a temperature between 40 and 80°C. g) optionally, add formulation aids during or after step d) of agitation; to obtain the composition of the invention.

[0025] Where the divalent or trivalent cation is chosen from Ca, Mg, Zn, Fe, Al, Cu, Ni, Mo and / or Mn and the lignin is chosen from organosolv lignin, Kraft lignin, soda lignin or derivatives thereof. Petition 870250090833, dated 06 / 10 / 2025, pp. 55 / 73 10 / 18

[0026] In a third aspect, the invention relates to the use of a polymer matrix modifying composition to impart anticorrosive, biocidal and mechanically improving properties to polymer matrices when this composition is mixed with the polymer matrix before curing. The composition is mixed in a final ratio between 0.1 and 5% w / w relative to the uncured polymer matrix.

[0027] The polymeric matrix is ​​chosen from thermosetting and thermoplastic polymers. Where polymeric resins within the thermosetting category are chosen from epoxy, polyurethane, polyurea, acrylic and / or polysiloxane resins, which are used as paints, varnishes or coatings; and these polymeric resins, once cured and forming a coating, exhibit improved biocidal, anticorrosive, hardness and adhesion properties compared to the resin without the composition.

[0028] On the other hand, plastics are chosen from PET, PP, HDPE, LDPE, ABS, PVC, polycarbonate, nylon, PVA and / or PLA, which are used to manufacture everyday objects; and where the plastics, once cured and forming objects, exhibit improved biocidal, anti-corrosive, hardness and adhesion properties compared to plastic without the composition.

[0029] The composition of the invention forms a structure in which the plant-derived polymer, modified lignin, is linked through the formation of a highly stable complex with divalent or trivalent cations, which determines that the composition is insoluble in water and has very low solubility in polar solvents in general. This represents a significant advantage over highly hazardous or toxic inhibitors, which are soluble in polar solvents, such as water, leading to their leaching over time from the polymer matrix. This differentiates the formulation of the invention from lignin with monovalent cations, such as sodium, which is partially soluble in water and whose affinity for water leads to a Petition 870250090833, dated 06 / 10 / 2025, pp. 56 / 73 11 / 18 water absorption of up to 15-20 w / w% under relative humidity conditions between 40-90°C at room temperature, generating defects in protective films formed from polymeric matrices.

[0030] On the other hand, the chemistry of this polymer matrix modifying composition allows for proper incorporation into an organic coating, since it exhibits a limited reaction with the polymer matrix during its preparation, application and curing, maintaining its inhibitory properties after the formation of the protective film. Furthermore, it is available in the form of particulate material or dispersion with particle sizes ranging from 50 nm to 100 microns.

[0031] This polymer matrix modifying composition acts against the generation of corrosion processes, either by generating damage to the organic coating or by forming defects that allow the diffusion of corrosive agents to the metallic surface. When corrosion occurs, metallic ions are generated as a result of the oxidation reaction of the metallic element, which induces an ion exchange reaction assisted by changes in concentration and pH in the defect zone, as a result of oxidation-reduction reactions. At this point, the organometallic complex of lignin and cation, according to the composition of the invention, dissociates, whereby the organic fraction of lignin is released, generating passivation of the surface through physical and, mainly, chemical adsorption, forming a compact precipitate that covers the anodic sites during corrosion.On the other hand, the metallic cation is capable of reacting through cathodic inhibition, delaying the generation of the cathodic reaction, which interrupts the corrosive process. This cannot occur with lignin with monovalent cations which, being partially soluble in water, are leached before corrosion occurs. On the other hand, the coordination of the organic compound with its inorganic counterpart seeks to limit the affinity of the molecular structure with polar solvents (in particular its behavior). Petition 870250090833, dated 06 / 10 / 2025, pp. 57 / 73 12 / 18 hygroscopic), whose interaction is recovered at the moment of complex dissociation, leaving the polar functional groups available to act as chemical adsorption sites on the metal surface. Furthermore, the use of lignin or its derivatives allows the coating to have greater mechanical strength, due to the hardness of the complex formed, as well as greater resistance to UV exposure, due to the properties of lignin's molecular structure.

[0032] The polymer matrix modifying composition of the invention, together with a polymer resin from the epoxy, polyurethane, polyurea, acrylic and polysiloxane resin groups, allows the formation of a modified coating useful for preventing corrosion of metallic surfaces. As already indicated, the vegetable origin of the precursors contained in the composition reduces the potential health risk to people who come into contact with it, both in the manufacturing process of paints and coatings, and in its use during application to metallic surfaces.

[0033] It is important to highlight that the composition of the invention is used as an additive in very low concentrations, of 5%, 1% or even less, managing to generate the effect of inhibiting corrosion, biocidal and modifying mechanical properties, which contrasts with the corrosion inhibitors available on the market, which must be used in much higher proportions. APPLICATION EXAMPLES

[0034] The following examples demonstrate the applicability of the development presented here, but the scope of the technology is not intended to be limited to these cases. Example 1: Preparation of the invention composition.

[0035] Compositions were prepared according to the invention, specifically compositions comprising the organometallic complexes M-Lignin Kraft, where M is a metallic cation that was chosen from Zn, Cu, Mn, Mg and Al. Petition 870250090833, dated 06 / 10 / 2025, pp. 58 / 73 13 / 18

[0036] Each complex, which constitutes the composition of the invention, was synthesized from 10 g of Kraft lignin, which were dissolved in distilled water with a total volume of 100 ml, adjusting its initial pH to pH 12.

[0037] This solution was kept at a temperature of 50°C and, subsequently, 50 ml of a 0.1 M solution of compounds with the cation of interest, or precursor compounds, was added dropwise.

[0038] After the addition of the precursor, each solution was kept under magnetic stirring for 4 hours. Subsequently, the solutions were left to stand for at least 8 hours, observing the sedimentation of the dark brown precipitate obtained during the reaction. The supernatant was removed and the precipitate was separated by centrifugation and then washed with distilled water, since, given that the compounds of the invention are insoluble in water, the counter-ions or unreacted compounds are washed away.

[0039] Each resulting compound was dried in an oven at 50°C for 24 hours.

[0040] The precursor compounds in each case were as follows: zinc acetate (Zn(CH3CO2)2), for the Zn2+ cation; copper sulfate pentahydrate (CuSO4 5H2O), for the Cu2+ cation; manganese sulfate monohydrate (MnSO4 H2O), for the Mn2+ cation; magnesium nitrate hexahydrate (Mg(NO3)2 6H2O), for the Mg2+ cation; and aluminum nitrate nonahydrate (Al(NO3)3) 9H2O), for the Al3+ cation.

[0041] To confirm correct incorporation, the content of metal ions in the compounds formed was determined, obtaining a content of 23.4% Zn; 15.5% Cu; 2.8% Mn; 2.7% Mg and 2.5% Al, all expressed as a percentage by weight.

[0042] The particles obtained by the synthesis method described above were observed by scanning electron microscopy, as shown in Figure 1. It can be seen that the particle size varied between Petition 870250090833, dated 06 / 10 / 2025, pp. 59 / 73 14 / 18 and 100 μπ. To verify the formation of the organometallic complex, the compound and its organic precursor were analyzed by infrared spectroscopy and Raman spectroscopy, shown in Figures 2 and 3. The infrared spectrum of lignin shows its own peaks at 3,330; 1,596; 1,413 and 1,122 cm⁻¹, which correspond to the vibration of the OH group, the aromatic groups of lignin and the CO and C=O vibrations, respectively. The spectrum of the complex shows a slight shift of the band to 3,350 cm⁻¹ and the appearance of a peak at 857 cm⁻¹, which is associated with the coordination of the metal ion with the hydroxyl groups of lignin. This was reaffirmed by the presence of a peak between 150 and 250 cm-1 in the Raman spectrum of the complex, which indicates the formation of a metal-oxygen bond, associated with the coordination of Zn with the functional groups of the lignin structure. Example 2: Anti-corrosive property of the composition of the invention as an additive in an epoxy coating.

[0043] To evaluate the anticorrosive capacity of the composition of the invention, prepared as indicated in Example 1, a two-component solvent-based epoxy coating was prepared, to which the composition of the invention, specifically the Kraft-Zinc lignin-based compound, was added. For comparative purposes, a control consisting of the resin without additive (B1) was used.

[0044] Two compositions were prepared according to the invention, where 0.5% of the composition of the invention (LgZn-0.5) was added to the epoxy coating, and another formulation to which 1.0% of the composition of the invention (LgZn-1.0) was added.

[0045] To evaluate the anticorrosive effect, A36 carbon steel panels with dimensions of 150x70 and 100x100 mm were painted with each of the prepared coatings: Control (Bl), 0.5% zinc lignin (LgZn-0.5) and 1.0% zinc lignin (LgZn-1.0). Petition 870250090833, dated 06 / 10 / 2025, pages 60 / 73 15 / 18

[0046] The painted panels were exposed for 336 hours in a salt spray chamber, according to the specifications of ASTM B117. Figure 4 shows the painted panels after their exposure in the salt spray chamber. A significant degree of corrosion can be observed in the panel painted with the Control formulation, Figure 4 a). In contrast, the panels painted with formulations containing the anticorrosive composition of the invention showed a better condition, with a limited percentage of the surface showing oxide presence for the LgZn-0.5 sample, Figure 4 b), and an oxide-free surface in the case of the LgZn-1.0 formulation, Figure 4 c).

[0047] In this way, a substantial improvement is observed in the anti-corrosion protection capacity of the epoxy resin modified with the composition of the invention.

[0048] To complement the visual assessment, the painted panels were analyzed using electrochemical impedance spectroscopy, the results of which are shown in Figure 5. A comparison between Bl and LgZn-1.0 can be observed, showing a difference of at least 1 order of magnitude in the impedance value at a frequency of 0.1 Hz. In the higher frequency region, the curves show similar behavior, with only a visible difference in the impedance value at low frequencies. This indicates the formation of an additional layer between the coating and the metallic substrate, which is attributed to the formation of a compact film through the formation of ferrous complexes.

[0049] This is objective proof of the effect of the invention's composition as a corrosion inhibitor. Example 3: Improver of the mechanical properties of the composition of the invention as an additive in an epoxy coating.

[0050] A two-component epoxy paint was formulated with the addition of Petition 870250090833, dated 06 / 10 / 2025, pp. 61 / 73 16 / 18 1% of the LgZn-1.0 additive was used to study the mechanical properties of adhesion and hardness through standard shear adhesion and pencil hardness tests. The test was performed on a metal panel coated with LgZn1.0 epoxy paint, where the dry coating was scratched with pencils of different hardnesses and the damage caused in each case was evaluated.

[0051] In both cases, an excellent response was obtained, achieving an adhesion rating of 5B, which indicates that 0% of the tested area was removed during the shear adhesion test, which corresponds to the best results rating. Similarly, the pencil hardness test showed a hardness result of 10H, which is the highest hardness within the scale, ranging from 6B (lowest hardness) to 10H (highest hardness).

[0052] Table 1.- Results of mechanical tests on an epoxy formulation including the composition of the invention at a concentration of 1%. Standard Result Pencil Hardness ASTM D3363 10 H Cut Adhesion ASTM D3359 5B

[0053] Using the same formulation presented previously, an accelerated aging study was conducted according to ISO 12944-6 to evaluate corrosion resistance through exposure in a spray chamber for 720 hours, based on ISO 9227. Among the results is the visual assessment based on ISO 4628, in which defects found due to corrosion during the accelerated aging test are classified. It is observed that the incorporation of the complex allows delaying the progression of corrosion under the coating during exposure in a salt spray chamber, as obtained based on ISO 4628-8.

[0054] Table 2.- Results of anticorrosive resistance after accelerated aging tests in a salt spray chamber. Standard Control Control + LgZn-10 Corrosion Grade, from the cut ISO 4628-8 2.5 mm 1.3 mm Petition 870250090833, dated 06 / 10 / 2025, pp. 62 / 73 17 / 18 Standard Control Control + LgZn-10 Degree of Cracking ISO 4628-4 0(S0) 0(S0) Degree of Scaling ISO 4628-5 0(S0) 0(S0)

[0055] Where Control is the two-component epoxy paint. Example 4: Antimicrobial activity of the composition of the invention as an additive in an acrylic coating.

[0056] An acrylic-based coating formulation was developed using the additive of the invention to evaluate its properties as an antimicrobial agent, and its effect was compared with a commercial silver-based biocide, as well as a formulation using unmodified lignin as a reference, i.e., Kraft lignin not subjected to the invention process. The formulations were studied by means of an assay under the ISO 22196 standard, which quantifies the colony-forming units on a surface and their evolution over time upon contact with the antimicrobial surface.

[0057] The control is the acrylic coating, and the additives: commercial, unmodified lignin and the formulation of the invention LgZn-1.0, were added in a final concentration of 1%.

[0058] Tables 3 and 4 below present the results of the antimicrobial activity of the paints formulated using the strains Escherichia coli and Staphylococcus aureus. It can be observed that, in both cases, the commercial biocide shows low or no antimicrobial activity in short contact times, with inhibition possible for periods exceeding 24 hours. A similar case is observed for the formulation including unmodified lignin, obtaining 92% inhibition in the case of Staphylococcus, but no inhibition of Escherichia coli after 2 hours. On the other hand, a much greater inhibition is achieved through the composition of the invention for both strains, achieving inhibition up to 2 orders of magnitude greater compared to the other formulations. For both strains, the inhibition is Petition 870250090833, dated 06 / 10 / 2025, pages 63 / 73 18 / 18 100% in the case of this last formulation.

[0059] With this, it is possible to demonstrate not only the inhibition over long periods, but it is also important to highlight the rapid antimicrobial action, equaling or improving the results obtained by copper and / or silver-based additives reported in the literature. This effect is achieved with a low dose of up to 0.3%.

[0060] Table 3 - Evaluation of antimicrobial efficacy against the Escherichia coli strain. Initial Concentration 2-Hour Concentration 24-Hour Concentration Control 4.7 x 10⁶ CFU / ml 1.4 x 10⁶ CFU / ml (70.2127%) <10 CFU / ml (100%) Control + Commercial Biocide 4.7 x 10⁶ CFU / ml 4.7 x 10⁶ CFU / ml (0%) <10 CFU / ml (100%) Control + Lignin 4.7 x 10⁶ CFU / ml 4.7 x 10⁶ CFU / ml (0%) <10 CFU / ml (100%) Control + LgZn-1.0 4.7 x 10⁶ CFU / ml 1.2 x 10⁵ CFU / ml (97.4468%) <10 CFU / ml (100%)

[0061] Table 4.- Evaluation of antimicrobial efficacy against the Staphylococcus aureus strain. Initial Concentration 2-Hour Concentration 24-Hour Concentration Control 3.0 x 10⁶ CFU / ml 3.9 x 10⁴ CFU / ml (98.700%) <10 CFU / ml (100%) Control + Commercial Biocide 3.0 x 10⁶ CFU / ml 3.8 x 10⁵ CFU / ml (87.333%) 20 CFU / ml (99.99981%) Control + Lignin 3.0 x 10⁶ CFU / ml 2.4 x 10⁵ CFU / ml (92.000%) <10 CFU / ml (100%) Control + LgZn-1.0 3.0 x 10⁶ CFU / ml 2.2 x 10³ CFU / ml (99.926%) <10 CFU / ml (100%) Petition 870250090833, dated 06 / 10 / 2025, pp. 64 / 73

Claims

1 / 2 Claims 1. - MODIFYING COMPOSITION of polymeric matrices characterized by comprising: - between 50 and 99% of an organic fraction consisting of lignin, chosen from organosolv lignin, Kraft lignin, soda lignin and / or their derivatives; - between 1 and 40% of divalent or trivalent inorganic cations chosen from Zn, Cu, Mn, Mg, Ca, Al, Fe, Ni and / or Mo; - between 0 and 10% of formulation auxiliaries, wherein the lignin and the cation form an organometallic complex.

2. A COMPOSITION according to claim 1, characterized in that the modified lignin is Kraft lignin or its derivatives.

3. METHOD FOR OBTAINING A COMPOSITION according to clause 1, characterized by comprising: a) providing an aqueous solution of modified lignin in an alkaline medium at a concentration between 2 and 30% by weight; b) maintaining at a temperature between 20 and 70°C with gentle stirring; c) adding by drop a solution of a salt of a divalent or trivalent cation chosen from salts of Zn, Cu, Mn, Mg, Ca, Al, Fe, Ni and / or Mo; d) incubating with stirring for between 1 and 24 hours; e) separating the precipitate from the solvent and washing; f) drying in an oven at a temperature between 40 and 80°C; g) optionally, adding formulation aids during or after step d) of stirring, to obtain the composition of the invention, where the lignin and the cation form an organometallic compound.

4. METHOD according to clause 3, characterized in that the modified lignin is chosen from organosolv lignin, Kraft lignin, soda lignin or derivatives thereof.

5. USE OF A MODIFYING COMPOSITION for polymeric matrices according to clause 1, characterized by imparting anti-corrosive, biocidal and / or mechanical property enhancement to the polymeric matrices, when the composition is homogeneously dispersed with the polymeric matrix before curing.

6. Use in accordance with clause 5, characterized by the fact that the polymer matrix modifying composition is mixed in a final proportion between 0.1 and 5% w / w in relation to the uncured polymer matrix.

7. USE in accordance with clause 6, characterized by the fact that the polymeric matrix is ​​chosen from thermosetting and / or thermoplastic polymers.

8. USE in accordance with clause 7, characterized by the fact that the polymeric resins are chosen from thermosetting polymers, such as epoxy, polyurethane, polyurea, acrylic and / or polysiloxane resins, which are used as paints, varnishes or coatings.

9. USE in accordance with clause 8, characterized by the fact that the polymeric resins, once cured and forming a coating, exhibit improved biocidal, anti-corrosive, hardness and / or adhesion properties compared to the resin without the composition.

10. USE in accordance with clause 7, characterized by the fact that the thermoplastic polymers are chosen from among the following types: PET, PP, HDPE, LDPE, ABS, PVC, polycarbonate, nylon, PVA and / or PLA, which are used to manufacture objects for everyday industrial or domestic use.

11. USE in accordance with clause 8, characterized by the fact that the plastics, once cured and transformed into objects, exhibit improved biocidal, anti-corrosive, hardness and / or adhesion properties compared to the plastic without the composition. Petition 870250090833, dated 06 / 10 / 2025, pp. 73 / 73

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