Processes for obtaining modified fibrilate cellulose, modified fibrilate cellulose, process of obtaining a polymeric composite with modified fibrilate cellulose, polymeric composite and uses

Description

1 / 20 PROCESSES FOR OBTAINING MODIFIED FIBRILLATED CELLULOSE, MODIFIED FIBRILLATED CELLULOSE, PROCESS FOR OBTAINING A POLYMERIC COMPOSITE WITH MODIFIED FIBRILLATED CELLULOSE, POLYMERIC COMPOSITE AND USES TECHNICAL FIELD

[0001] The present invention belongs to the field of modified cellulosic materials and relates to a process for obtaining modified fibrillated cellulose (MFC) by extruder processing in the presence of deep eutectic solvents (DES), the modified fibrillated cellulose obtained and its use. The present invention also relates to a process for obtaining a polymer composite with modified fibrillated cellulose, a polymer composite with modified fibrillated cellulose and its use. The modified fibrillated cellulose obtained exhibits an excellent degree of defibrillation and the process employs reduced amounts of DES compared to processes known in the state of the art. BACKGROUND OF THE INVENTION

[0002] In the current context of the search for sustainability, the use of cellulose and its derivatives has increased significantly and has shown great potential for application in different markets. Cellulose can be found in different forms such as bleached or unbleached pulp, microfibrillated cellulose, nanofibrillated cellulose, nanocrystalline cellulose, among other known forms.

[0003] One of the forms of cellulose presentation is fibrillated cellulose, which can be microfibrillated or nanofibrillated, and this can be obtained by different processes, such as enzymatic, chemical or mechanical processes, with mechanical processes being the most common, in which shear forces, decompression and the action of agents capable of separating the fibrils are applied. Petition 870250008493, dated 01 / 31 / 2025, page 13 / 44 2 / 20 of cellulose, either by replacing the hydrogen bonds between the fibers or by interacting with water and / or another agent.

[0004] There are many known mechanical processes for fibrillating cellulose pulp, including the use of homogenizers, grinders, microfluidizers, refiners, among others. However, these processes consume significant amounts of energy and produce aqueous suspensions with low solids content (around 5%). An alternative capable of producing high solids content (20-40%) is the use of twin-screw extruders. In this process, the pulp passes through two co-rotating screws arranged in a closed cylinder. A challenge of this technique is the optimization of the screw profile and other processing conditions capable of achieving sufficient shear force necessary to induce cellulose defibrillation without degrading it.

[0005] Mechanical processing is usually energy-intensive, so the use of pulp pretreatment processes is often necessary to avoid excessive energy consumption. Among the pretreatment agents, enzymes, alkalis, organic and inorganic salts, and other materials can be mentioned.

[0006] Combining these pretreatment processes with mechanical defibrillation can, in some cases, result in processes where the microfibrils obtained exhibit the desired properties and degree of refinement and lower energy consumption, although they require reagents and more processing steps.

[0007] An example of pulp pretreatment is the use of ionic liquids, as revealed in documents WO 2022 / 027150 and WO 2011 / 114004. However, it is well known that this alternative has the disadvantage of the high cost of ionic liquids, their toxicity, Petition 870250008493, dated 01 / 31 / 2025, page 14 / 44 3 / 20 difficulty in removing the final product and, in many cases, corrosive action on the equipment.

[0008] One class of material that can be considered an ionic liquid is deep eutectic solvents (DES). Some ionic liquids are also called low transition temperature mixtures (LTTMs) when it is not possible to identify the melting point of these mixtures. These materials are often derived from renewable sources and, in many cases, are natural, exhibiting low or no toxicity, as well as low cost. When derived from renewable sources, they are called NADES, from the English "Natural Deep Eutectic Solvents".

[0009] Deep eutectic solvents (DES), and more particularly natural deep eutectic solvents (NADES), can be considered ionic liquids, but they are less toxic and have several advantages over classic ionic liquids. Currently, these materials have been used as plasticizers for natural polymers.

[0010] Eutectic solvents are characterized by a mixture of two substances in a specific proportion where the observed melting point is minimal compared to the melting point of the pure components. The eutectic point is characterized by the coexistence of the liquid and solid phases of the components. In the case of materials that do not crystallize, as occurs with many deep eutectic liquids, it is not possible to identify the melting point, but rather the glass transition temperature (Tg), and in this case, the mixtures are called "low transition temperature mixtures (LTTMS)".

[0011] Figure 1 shows a typical phase diagram of a deep eutectic solvent where it can be observed that the melting temperature of the mixture at a given composition is Petition 870250008493, dated 01 / 31 / 2025, page 15 / 44 4 / 20 very low, characterizing the deep eutectic solvent in relation to a conventional eutectic.

[0012] DES compositions formed, for example, by choline chloride and glycerol do not exhibit a melting point relative to glycerol, and have been characterized in terms of glass transition temperatures, therefore being better characterized as LTTMs, however they are treated as DES in many publications. DES or LTTMs are, due to their low cost, low toxicity and technical benefits, much more advantageous than ionic liquids and the use of these materials is described in some documents, listed below.

[0013] Document WO 2022 / 042842 A1 refers to the method of manufacturing fibrillated cellulose using low transition temperature (LTTM) mixtures formed by ammonium formate and a mono- or dicarboxylic acid.

[0014] Document WO 2018 / 219638 A1 describes a process for obtaining nanocellulose using a swelling agent, a binary deep eutectic solvent (DES) of choline chloride and urea or choline chloride and ethanolamine or also a ternary DES such as choline halide and glycerol / DBN or glycerol / DBU.

[0015] Document CN 112982003 A mentions a method for preparing sulfonated modified cellulose using a deep ternary eutectic system. According to the document, for pulp pretreatment, a deep ternary eutectic solvent, composed of sulfamic acid, urea, and choline chloride, is used; the method is efficient for obtaining sulfonated nanocellulose.

[0016] Document CN 109235102 B discloses a procedure that uses deep eutectic solvents to manufacture cellulose nanofibrils in a pretreatment step followed by mechanical treatment using a high-pressure homogenization micro-jet. Petition 870250008493, dated 01 / 31 / 2025, page 16 / 44 5 / 20

[0017] The document by LIU, W. et al. “Sustainable preparation of cellulose nanofibrils via choline chloride-citric acid deep eutectic solvent pretreatment combined with high-pressure homogenization” in Carbohydrate Polymers, v. 267, n. 4, p.118220, 2021, presents a system that involves a DES formed by choline chloride and citric acid as a pretreatment of cellulose fibers under temperatures ranging from 80 to 100°C for 2 hours.

[0018] As can be seen, the use of DES or LTTMs as pretreatment agents requires additional pulp pretreatment steps before fibrillation is actually carried out, and this requires large quantities of pretreatment agents (DES or LTTMs), which are commonly mixed with the cellulosic material in containers and agitated for 30 minutes to 4 hours at temperatures of around 50-100°C. After this initial process, the material is purified by washing, so that it can then be processed in a twin-screw extruder.

[0019] An example of the use of eutectic solvents and extrusion is found in the document by MNSARI, A. et al. (2023) “High Content Microfibrillated Cellulose Suspensions Produced from Deep Eutectic Solvents Treated Fibres Using Twin-Screw Extruder” in Chemistry Africa, v. 6, n. 5, p. 2297-2307, 2023, which reveals a methodology that uses a pretreatment of the fibers with DES followed by a mechanical treatment where the pulp is subjected to a refining mill and 4 extrusion cycles in a twin-screw extruder. Processes like this tend to be quite slow, employ large quantities of reagents and require a rather complex purification step due to the high reagent / cellulose ratio.

[0020] Given the above, it is clear that, despite the technical advantages of using DES for pulp modification / fibrillation, there is a great difficulty in employing them for this purpose. Petition 870250008493, dated 01 / 31 / 2025, p. 17 / 44 6 / 20, it is necessary to make viable a faster, more economical process that actually results in a technical advance compared to the processes most commonly used today, which are conducted in equipment where high shear and decompression forces are employed.

[0021] In view of this need, the present invention relates to a new and inventive process for producing modified fibrillated cellulose, in which processing takes place in a single step, via reactive extrusion, in a twin-screw extruder with a reduced ratio of eutectic solvents (DES) / cellulosic fibers. This process requires post-purification via washing; however, it is a much simpler and faster process due to the reduced amount of reagents employed, i.e., a low DES / cellulosic fiber ratio. Additionally, this new process makes it possible to reduce costs and improve material quality, paving the way for new products. SUMMARY OF THE INVENTION

[0022] The present invention relates to a process for obtaining modified fibrillated cellulose (MFC) by extruder processing in the presence of deep eutectic solvents (DES), the modified fibrillated cellulose obtained and its use. The present invention also relates to a process for obtaining a polymer composite with modified fibrillated cellulose, a polymer composite with modified fibrillated cellulose and its use.

[0023] A first embodiment of the invention relates to a process for obtaining a modified fibrillated cellulose, comprising the following steps: a) to provide a cellulose pulp with a solids content of 25 to 50%; b) add a deep eutectic solvent to the pulp from step a); Petition 870250008493, dated 01 / 31 / 2025, page 18 / 44 7 / 20 c) mix the components from steps a) and b) in a mixer or by means of feeders directly in the feeding zone of an extruder; d) extrude this mixture in an extruder until a material is formed where the pulp is in a defibrillated state; e) Wash the material obtained in step d) with water, using a ratio of 20 times the volume of water to the weight of dry cellulose base, and repeat for 3 cycles. f) filter the material obtained in step e) until it reaches a solids content of at least 25%.

[0024] In one aspect of the invention, the cellulose pulp of step a) preferably has a solids content of 35%.

[0025] In one aspect of the invention, the deep eutectic solvent (DES) is selected from the group of materials composed of a proton donor such as glycerol, citric acid, urea, glycerol, adipic acid, acetic acid, oxalic acid, malic acid, lactic acid, malonic acid, succinic acid, formic acid, levurine acid, maleic acid, ethylene glycol and a proton acceptor such as choline chloride, preferably formed by a 1:2 mixture of choline chloride / urea.

[0026] In one aspect of the invention, the extrusion temperature of step d) is 30°C to 100°C.

[0027] In one aspect of the invention, the filtration in step f) is carried out until the preferred solids content of 35% is reached.

[0028] A second embodiment of the invention relates to a fibrillated cellulose modified with eutectic solvents and a minimum solids content of 25%, obtained by the process disclosed herein. The modified fibrillated cellulose exhibits characteristics of greater dispersibility in liquid media, with viscosity in the range Petition 870250008493, dated 01 / 31 / 2025, page 19 / 44 8 / 20 from 20 to 130 cP (measured using a rheometer, oscillatory mode, cone-plate geometry, 0.85% solids, 12.5 rpm) and A-fines content from 50 to 95%, measured using the FS5 fiber morphology analyzer.

[0029] A third embodiment of the invention relates to the use of modified fibrillated cellulose for direct use as an additive in the manufacture of paper, cardboard, inks, water-based adhesives and polymer composites or films.

[0030] A fourth embodiment of the invention relates to a process for obtaining a polymer composite with fibrillated cellulose modified with eutectic solvents, comprising the following steps: a) to provide a fibrillated cellulose modified with eutectic solvents and a solids content between 30 and 40%; b) replace the water present in the cellulose from step a) with isopropanol by means of: i. a mixture of 1.72 times the volume of isopropanol relative to the weight of wet pulp, this volume being divided into 4 parts and each part used for a washing process, totaling 4 washing cycles; ii. pressing the mixture until the cellulose has a water content of less than 5% relative to the cellulose; c) add an anhydride to the cellulose obtained in step b), using a gravimetric or volumetric addition system in a twin-screw extruder and proceed with extrusion; d) Wash the cellulose obtained in step c) by adding 4 times the volume of anhydrous ethanol or isopropanol relative to the weight of wet pulp, let it stand for 10 minutes and filter under reduced pressure to remove excess liquid, repeat this process twice; Petition 870250008493, dated 01 / 31 / 2025, page 20 / 44 9 / 20 e) partially dry the cellulose obtained in step d) in a forced-air oven or equivalent equipment at a temperature of 50 to 70°C until a material with 20% moisture is obtained; f) process the cellulose obtained in step e) in a twin-screw extruder together with a thermoplastic polymer, maintaining a proportion of 5% and 50% cellulose in relation to the thermoplastic polymer; and g) to obtain a composite material.

[0031] The anhydride used in the process of obtaining a polymer composite with modified fibrillated cellulose can be selected from the group consisting of products of the reaction of olefins and maleic anhydride, preferably Alkenyl Succinic Anhydride (ASA).

[0032] In an optional aspect of the process for obtaining a polymer composite, anhydrous ethanol or isopropanol from the washing step d) is used in a 1:4 ratio (wet pulp / anhydrous ethanol or isopropanol).

[0033] In one aspect of the process of obtaining a polymer composite, in step e) drying is carried out by means of an oven or equivalent equipment, at 70°C.

[0034] The polymer in step f) of the process for obtaining a polymer composite may be a thermoplastic polymer, preferably a polyolefin selected from the group consisting of high-density polyethylene (HDPE), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), polypropylene (PP) and ethylene-propylene copolymers.

[0035] A fifth embodiment of the invention relates to a polymer composite obtained by the process disclosed herein, comprising a thermoplastic polymer and a modified fibrillated cellulose. In one aspect of the invention, the polymer composite Petition 870250008493, dated 01 / 31 / 2025, page 21 / 44 10 / 20 exhibits the typical characteristics of a reinforced material, with greater stiffness and less deformation at rupture.

[0036] A sixth embodiment of the invention relates to the use of the polymer composite for various products, such as injection molded products, extruded products, such as sheets, profiles, flat films, injection-blow molded products and others that can be processed in the form of thermoplastic material. BRIEF DESCRIPTION OF THE FIGURES

[0037] To assist in identifying the main characteristics of the process for obtaining modified fibrillated cellulose, the modified fibrillated cellulose obtained, the process for obtaining a polymer composite with modified fibrillated cellulose, and the polymer composite with modified fibrillated cellulose, some figures are presented, which are referenced as follows.

[0038] FIG. 1 presents a schematic phase diagram of a deep eutectic solvent and of a system considered regular (Eutectic).

[0039] FIG. 2 presents the illustrative flowchart of the fibrillated cellulose preparation processes.

[0040] FIG. 3 is a representative image of DES-modified fibrillated cellulose, formed from choline chloride and glycerol, via extrusion.

[0041] FIG. 4 is a representative image of modified fibrillated cellulose, with a solids content of 92%, after washing with water and isopropyl alcohol.

[0042] FIGS. 5A-5B show optical micrograph images of fibrillated cellulose modified with DES formed from choline chloride and glycerol, in a cellulose fiber / DES ratio of 1:1, via extrusion. Petition 870250008493, dated 01 / 31 / 2025, page 22 / 44 11 / 20

[0043] FIGS. 6A-6B show optical micrograph images of fibrillated cellulose modified with DES formed from choline chloride and glycerol, in a cellulose fiber / DES ratio of 1:2, via extrusion.

[0044] FIGS. 7A-7B show optical micrograph images of fibrillated cellulose modified with DES formed from choline chloride and glycerol, in a cellulose fiber / DES ratio of 1:3, via extrusion.

[0045] FIGS. 8A-8B show optical micrograph images of fibrillated cellulose modified with DES formed from choline chloride and glycerol, in a cellulose / DES ratio of 1:4, via extrusion.

[0046] FIGS. 9A-9C show SEM micrograph images of fibrillated cellulose modified with DES formed from choline chloride and glycerol, in a cellulose fiber / DES ratio of 1:4, via extrusion.

[0047] FIGS. 10A-10C show SEM micrograph images of fibrillated cellulose modified with DES formed from choline chloride and citric acid, in a cellulose / DES ratio of 1:4, via extrusion.

[0048] FIGS. 11A-11C show SEM micrograph images of fibrillated cellulose modified with DES formed from choline chloride and urea, in a cellulose / DES ratio of 1:4, via extrusion.

[0049] FIG. 12 shows the screw profile of the extruder used in the defibrillation of modified fibrillated cellulose. DETAILED DESCRIPTION OF THE INVENTION

[0050] The present invention discloses a process for obtaining modified fibrillated cellulose, using deep eutectic solvents (DES), via extrusion in a twin-screw extruder, as indicated in the flowchart of Figure 2, as well as Petition 870250008493, dated 01 / 31 / 2025, page 23 / 44 12 / 20 the modified fibrillated cellulose obtained and its use. Furthermore, the present invention relates to a process for obtaining a polymer composite with fibrillated cellulose modified with eutectic solvents, polymer composites with fibrillated cellulose modified with eutectic solvents and their use.

[0051] The term deep eutectic solvents (DES) refers to a subclass of low transition temperature mixtures (LTTMs), characterized by a significant reduction in melting point compared to their individual components. DES can be natural (“Natural Deep Eutectic Solvents” - NADES) or not. In addition, ionic liquids are also considered a subclass of LTTMs, differing from DES in that they are composed of cations and anions, forming molten salts with a low melting point. When it is not possible to identify a clear melting point in these mixtures, they are generically classified as LTTMs, encompassing both DES and ionic liquids.

[0052] The previous technique already presented methods for obtaining fibrillated cellulose. However, despite these methods being in constant development and advancing technically day by day, there is still a need to find solutions related to some aspects such as: reducing energy consumption, reducing processing time, and not degrading the fiber at high temperatures and shear, so that it is possible to maintain or improve the characteristics of the fibers after fibrillation. These aspects are fundamental for new fields of application of fibrillated cellulose to be achieved.

[0053] Although processing in a twin-screw extruder is known to accelerate chemical reactions in the method known as reaction-extrusion (REX), it is also known that the defibrillation process requires a pulp swelling step, followed by the separation of fibrils due to substitution. Petition 870250008493, dated 01 / 31 / 2025, page 24 / 44 13 / 20 of the fiber-to-fiber hydrogen bonds are replaced by solvent-to-fiber bonds. Therefore, it is surprising that a single-step processing process with a residence time (time elapsed between feeding and material exit) of less than 5 minutes, as in the process of this invention, leads to such significant results.

[0054] Furthermore, the use of DES as fiber pretreatment agents is also known in the state of the art. Pretreatments always occur before adding the fiber to the extruder, requiring prior preparation where large quantities of DES are mixed with the cellulosic material, requiring agitation and high temperatures for the treatment to take place. After this step, it is necessary to purify the treated fibers so that they can then be added to the extruder and the final material obtained.

[0055] Some examples of deep eutectic solvents (DES) are given in Table 1. Table 1. Deep eutectic solvents that can be employed within the scope of the present invention. Salt HBD (hydrogen bond donor) Salt (HBD molar ratio) Choline Chloride Glycerol 1 2 Choline Chloride Urea 1 2 Choline Chloride Citric Acid 1 1 Choline Chloride Adipic Acid 1 1 Choline Chloride Acetic Acid 2 1 Choline Chloride Oxalic Acid 1 1 Choline Chloride Malic Acid 1 1 Choline Chloride Lactic Acid 1 1 Choline Chloride Malonic Acid 1 1 Choline Chloride Succinic Acid 1 1 Choline Chloride Formic Acid 2 1 Choline Chloride Levurinic Acid 1 2 Choline Chloride Maleic Acid 1 1 Choline Chloride Ethylene Glycol 1 2 Petition 870250008493, dated 01 / 31 / 2025, page 25 / 44 14 / 20

[0056] Unexpectedly, the inventors of the present invention have developed a process for obtaining modified fibrillated cellulose by processing it in a twin-screw extruder in the presence of mixtures called deep eutectic solvents (DES). The most relevant aspect is the fact that the processing takes place in only one step, with a residence time on the order of minutes and, therefore, with reduced processing time when compared to other methods, such as reaction in mixers and batch reactors, and at low or moderate temperatures (30 to 100°C), avoiding fiber degradation, and with a very positive result in relation to defibrillation. The purification of the modified fibrillated cellulose occurs after its production, which reduces the consumption of reagents, makes the process more agile, and allows for the easy recovery of these reagents, making the process surprisingly advantageous.

[0057] One embodiment of the invention relates to a process for obtaining a modified fibrillated cellulose, comprising the following steps: a) to provide a cellulose pulp with a solids content of 25 to 50%; b) add a deep eutectic solvent to the pulp from step a); c) mix the components from steps a) and b) in a mixer or by means of feeders directly in the feeding zone of an extruder; d) extrude this mixture in an extruder until a material is formed where the pulp is in a defibrillated state; Petition 870250008493, dated 01 / 31 / 2025, page 26 / 44 15 / 20 e) Wash the material obtained in step d) with water, using a ratio of 20 times the volume of water to the weight of dry cellulose base, and repeat for 3 cycles. f) filter the material obtained in step e) until it reaches a solids content of at least 25%.

[0058] According to the present invention, cellulose pulp can be bleached, unbleached or semi-bleached and can be obtained from different types of processes, whether mechanical, chemical, thermal or enzymatic.

[0059] Cellulose pulp can be derived from different sources, preferably from hardwood (short fiber), such as eucalyptus, or softwood (long fiber), such as pine. Preferably, the cellulose pulp is bleached eucalyptus pulp, obtained through the kraft process.

[0060] In some embodiments of the invention, the cellulose pulp is dewatered by pressing and / or filtration until a solids content of 25 to 50% is reached.

[0061] Deep eutectic solvents (DES) can be selected from the group of materials composed of a proton donor such as glycerol, citric acid, urea, glycerol, adipic acid, acetic acid, oxalic acid, malic acid, lactic acid, malonic acid, succinic acid, formic acid, levurine acid, maleic acid, ethylene glycol and a proton acceptor such as choline chloride, preferably formed by a 1:2 mixture of choline chloride / urea.

[0062] In step d) of the extrusion process, the cellulose defibrillation process occurs.

[0063] The extruder used in the process of the present invention is a twin-screw extruder and the extrusion temperature is in the range of 30°C to 100°C, preferably in the range of 30°C to 50°C. The profile of the screw used is shown in Figure 12. Petition 870250008493, dated 01 / 31 / 2025, page 27 / 44 16 / 20

[0064] In one embodiment of the invention, the washing of the material obtained in step d) is carried out with water, preferably distilled water. For washing with water, at least 3 cycles are performed to ensure the removal of the reagents.

[0065] In an optional embodiment of the invention, after washing with water (step e) of the process, the material obtained in step d) can undergo complete washing with isopropyl alcohol to obtain fibrillated cellulose with a high solids content. At least three washes with alcohol are necessary to remove the water without causing the hornification effect on the fibers. The resulting microfibrillated cellulose material, with a solids content between 90 and 95%, can be easily redispersed in aqueous solutions.

[0066] Figure 3 represents the fibrillated cellulose obtained after applying the process described in its first embodiment, and Figure 4 represents the fibrillated cellulose after washing with isopropyl alcohol and reaching 92% solids.

[0067] In one aspect of the invention, the filtration of step f) is carried out until the preferred solids content of at least 25% is reached. The filtration occurs after each washing cycle, where, at the end of each cycle, the pulp is filtered under reduced pressure.

[0068] Another embodiment of the invention relates to a fibrillated cellulose modified with eutectic solvents and a solids content of at least 25%.

[0069] Modified fibrillated cellulose exhibits characteristics of greater dispersibility in liquid media, with viscosity in the range of 20 to 130 cP (measured in a rheometer, oscillatory mode, cone-plate geometry, 0.85% solids, 12.5 rpm) and A-fines content of 50 to 95%, measured using the FS5 fiber morphological analyzer. Petition 870250008493, dated 01 / 31 / 2025, page 28 / 44 17 / 20

[0070] Modified fibrillated cellulose can be used directly as an additive in the manufacture of paper, cardboard, inks, water-based adhesives and polymer composites or films.

[0071] Another embodiment of the invention relates to a process for obtaining a polymer composite with fibrillated cellulose modified with eutectic solvents, comprising the following steps: a) to provide a fibrillated cellulose modified with eutectic solvents and a solids content between 30 and 40%; b) replace the water present in the cellulose from step a) with isopropanol by means of: i. a mixture of 1.72 times the volume of isopropanol relative to the weight of wet pulp, this volume being divided into 4 parts and each part used for a washing process, totaling 4 washing cycles; ii. pressing the mixture until the cellulose has a water content of less than 5% relative to the cellulose; c) add an anhydride to the cellulose obtained in step b), using a gravimetric or volumetric addition system in a twin-screw extruder and proceed with extrusion; d) Wash the cellulose obtained in step c) by adding 4 times the volume of anhydrous ethanol or isopropanol relative to the weight of wet pulp, let it stand for 10 minutes and filter under reduced pressure to remove excess liquid, repeat this process twice; e) partially dry the cellulose obtained in step d) in a forced-air oven or equivalent equipment at a temperature of 50 to 70°C until a material with 20% moisture is obtained; Petition 870250008493, dated 01 / 31 / 2025, page 29 / 44 18 / 20 f) process the cellulose obtained in step e) in a twin-screw extruder together with a thermoplastic polymer, maintaining a proportion of 5% and 50% cellulose in relation to the thermoplastic polymer; and g) to obtain a composite material.

[0072] In some embodiments of the invention, the anhydride added in step c) is selected from the group consisting of the reaction products of olefins and maleic anhydride, preferably Alkenyl Succinic Anhydride (ASA).

[0073] The drying of step e) is carried out by means of an oven or equivalent equipment at 70°C.

[0074] The polymer used in step f) is a thermoplastic polymer, preferably a polyolefin. In preferred embodiments, the polyolefin is selected from the group consisting of high-density polyethylene (HDPE), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), polypropylene (PP), and propylene-ethylene copolymers.

[0075] Another embodiment of the present invention relates to a polymeric composite obtained from modified fibrillated cellulose.

[0076] Deep eutectic solvent-modified fibrillated cellulose polymer composite exhibits improved mechanical properties compared to synthetic polymers. The polymer composite typically exhibits greater stiffness than the polymer matrix employed, such as HDPE.

[0077] Another embodiment of the invention relates to the use of the polymer composite for applications in various products, such as injection molded products, extruded products, such as sheets, profiles, flat films, injection-blow molded products and others that can be processed in the form of thermoplastic material. Petition 870250008493, dated 01 / 31 / 2025, page 30 / 44 19 / 20 EXAMPLES

[0078] The following examples, described in detail, serve to illustrate embodiments of the present invention without, however, limiting the scope of protection thereof. Example 1 - Preparation of Deep Eutectic Solvents (DES) and obtaining modified fibrillated cellulose

[0079] DES was prepared comprising choline chloride and glycerol (molar ratio 1:2), by mixing 11.38 g of glycerol and 8.62 g of choline chloride in a magnetic stirrer heated to a temperature of 100 °C for approximately 1 hour, until a clear and homogeneous liquid was obtained.

[0080] In parallel, cellulose pulp was also prepared, using 183 g of wet pulp with approximately 10.9% solids, i.e., 20 g of dry basis cellulose. This pulp was filtered under reduced pressure to remove excess water, leaving approximately 60 g of pulp, corresponding to approximately 33% solids.

[0081] 20 g of DES was added to the pulp, containing 20 g of cellulose, maintaining a cellulose / DES ratio of 1:1, until the liquid completely enveloped the cellulose. Other cellulose / DES ratios can be used, as shown in Table 2. Table 2. Recommended proportions of cellulose / DES Cellulose: DES Cellulose mass (dry basis) DES mass 1:2 20g 40g 1:3 20g 60g 1:4 20g 80g

[0082] The mixture was transferred to a twin-screw extruder, L / D 40, with free-flowing head. The defibrillation process operated at a temperature of 100 °C and a screw speed of 200 rpm. Petition 870250008493, dated 01 / 31 / 2025, page 31 / 44 20 / 20

[0083] After the defibrillation (extrusion) process, the material was washed with distilled water to remove the DES. This process required at least 3 cycles, using 300 mL of water in each, and at the end of each cycle, the material was filtered under reduced pressure.

[0084] Optionally, after washing with water, the material can undergo a complete wash with isopropyl alcohol to obtain a pulp with a high solids content. At least three washes with alcohol are necessary to remove water without causing hornification of the fibers. The resulting microfibrillated cellulose material, with approximately 92% solids, can be easily redispersed in aqueous solutions.

[0085] The processed pulp was found to be defibrillated. Figures 5-8 obtained by optical microscopy show the appearance of the fibers after processing, while figures 8 to 11 show the fibers through images obtained by scanning electron microscopy (SEM).

[0086] It should be understood that the embodiments described above are merely illustrative and that various modifications may be made to them by a person skilled in the art without departing from the scope of the present invention. Consequently, the present invention should not be considered limited to the exemplary embodiments described in this patent application. Furthermore, the present disclosure may include matter not claimed at present, but which may be claimed in the future in combination with or separately from the features claimed herein. Petition 870250008493, dated 01 / 31 / 2025, pp. 32-44

Claims

1 / 4 CLAIMS 1. Process for obtaining a modified fibrillated cellulose, characterized in that it comprises the following steps: a) providing a cellulose pulp with a solids content of 25 to 50%; b) adding a deep eutectic solvent to the pulp from step a); c) mixing the components from steps a) and b) in a mixer or by means of feeders directly in the feeding zone of an extruder; d) extruding this mixture in an extruder until the formation of a material where the pulp is in a defibrillated state; e) washing the material obtained in step d) with water, using a ratio of 20 times the volume of water in relation to the weight of dry basis cellulose and repeating for 3 cycles; f) filtering the material obtained in step e) until it reaches a solids content of at least 25%.

2. Process according to claim 1, characterized in that the cellulose pulp from step a) has a solids content of preferably 30%.

3. Process according to claim 1, characterized in that the deep eutectic solvent (DES) is selected from the group of materials composed of a proton donor such as glycerol, citric acid, urea, adipic acid, acetic acid, oxalic acid, malic acid, lactic acid, malonic acid, succinic acid, formic acid, levurine acid, maleic acid, ethylene glycol and a proton acceptor such as choline chloride, preferably formed by a 1:2 mixture of choline chloride / urea. Petition 870250008493, dated 01 / 31 / 2025, page 33 / 44 2 / 4 4. Process according to any one of claims 1 to 3, characterized in that the extrusion temperature of step d) is from 30°C to 100°C.

5. Process according to any one of claims 1 to 4, characterized in that the filtration of step f) is carried out until the preferred solids content of 25% is reached.

6. Modified fibrillated cellulose obtained by the process defined in any one of claims 1 to 5, characterized by having a viscosity in the range of 20 to 130 cP (measured in a rheometer, oscillatory mode, cone-plate geometry, 0.85% solids, 12.5 rpm) and a Fines A content of 50 to 95%, measured using the FS5 fiber morphological analyzer.

7. Use of the modified fibrillated cellulose defined in claim 6, characterized by the fact that it is for direct use as an additive in the manufacture of paper, cardboard, inks, water-based adhesives and polymeric composites or films.

8. Process for obtaining a polymer composite with modified fibrillated cellulose as defined in claim 6, characterized in that it comprises the following steps: a) providing a modified fibrillated cellulose with eutectic solvents and a solids content between 30 and 40%; b) replacing the water present in the cellulose from step a) with isopropanol by means of: i. mixing 1.72 times the volume of isopropanol relative to the weight of wet pulp, this volume being divided into 4 parts and each part being used for a washing process, totaling 4 washing cycles; Petition 870250008493, dated 01 / 31 / 2025, page 34 / 44 3 / 4 ii.a) Press the mixture until the cellulose has a water content of less than 5% relative to the cellulose; b) Add an anhydrous ethanol to the cellulose obtained in step b) using a gravimetric or volumetric addition system in a twin-screw extruder and proceed with extrusion; c) Wash the cellulose obtained in step c) with the addition of 4 times the volume of anhydrous ethanol or isopropanol relative to the weight of wet pulp, let it stand for 10 minutes and filter under reduced pressure to remove excess liquid, repeat this process twice; d) Partially dry the cellulose obtained in step d) in a forced-air oven at a temperature of 50 to 70°C until a material with 20% moisture is obtained; e) Process the cellulose obtained in step e) in a twin-screw extruder together with a thermoplastic polymer, maintaining a 5% to 50% cellulose-to-thermoplastic polymer ratio; f) Obtain a composite material.

9. Process according to claim 8, characterized in that the anhydride is selected from the group consisting of reaction products of olefins and maleic anhydride, preferably Alkenyl Succinic Anhydride (ASA).

10. Process according to claim 8, characterized in that step d) is optionally performed.

11. Process according to claim 8, characterized in that in step e) the drying is carried out by means of an oven with air circulation at 70°C.

12. Process according to claim 8, characterized in that the polymer of step f) is a thermoplastic polymer, preferably a polyolefin selected from the group Petition 870250008493, dated 01 / 31 / 2025, page 35 / 44 4 / 4 consisting of high-density polyethylene (HDPE), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), polypropylene (PP) and ethylene-propylene copolymers.

13. Polymer composite obtained by the process defined in any one of claims 8 to 12, characterized in that it comprises a thermoplastic polymer and a modified fibrillated cellulose.

14. Use of the polymeric composite defined in claim 13, characterized by being suitable for applications in injection-molded products, extruded products such as boots, profiles, flat films, injection-blow molded products and others that can be processed in the form of a thermoplastic material. Petition 870250008493, dated 01 / 31 / 2025, pp. 36 / 44

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