METHOD OF DRYING FIBRILLATED CELLULOSE, FIBRILLATED CELLULOSE, POLYMERIC COMPOSITE COMPOSITION AND USES

Description

1 / 17 METHOD OF DRYING FIBRILLATED CELLULOSE, FIBRILLATED CELLULOSE, POLYMERIC COMPOSITE COMPOSITION AND USES FIELD OF THE INVENTION

[001] The present invention relates to a method for drying fibrillated cellulose by spouting bed, in which the physicochemical properties of the cellulose are preserved, even after redispersion. The invention also relates to a dried fibrillated cellulose with preserved properties and to the use of this fibrillated cellulose. The invention further relates to a polymer composite composition containing said spouted-bed dried fibrillated cellulose and to the use of said composition. BACKGROUND OF THE INVENTION

[002] With regard to the development of new products and processes, it can be seen that there is currently a great concern among companies and researchers to generate products and processes with less environmental impact. One of the most sought-after alternatives is the replacement of materials from petrochemical sources with materials from renewable and biodegradable sources.

[003] Within this context, the search for the use of natural fibers, such as cellulose, stands out because it is an abundant material in nature, derived from renewable plant sources, and because it presents advantages such as: high availability, promotion of mechanical resistance, biodegradability, low density, among others. Cellulose can be applied in various types of products and, depending on how it is treated, it can also present disadvantages, such as being hygroscopic, having low thermal resistance and consequent degradation, Petition 870240111317, dated 12 / 30 / 2024, page 15 / 37 2 / 17 incompatibility with polymeric matrices, need for high refining energy consumption, among others.

[004] Given that the production process of fibrillated cellulose is carried out in an aqueous medium and that the product is in suspension form, it is known that, in order for fibrillated cellulose to be more easily transported and also incorporated into different applications, it is necessary to dry it. This process is normally carried out in equipment and methods commonly used for cellulose drying, such as vacuum drying, high-temperature evaporation, and spray drying; however, these methods tend to cause fiber degradation, altering their properties, and also promote the formation of agglomerates, which impair the homogeneous incorporation of the product in different applications. These agglomerates are formed by the hornification phenomenon. This process occurs due to the formation of hydrogen bonds between fibers during drying. These agglomerates are difficult to redisperse, impacting the physicochemical properties of the post-drying dispersion.

[005] Regarding drying processes, there are processes that are more suitable for certain types of products, depending on the objective to be achieved at the end of the drying process. For example, freeze-drying or fluidized bed drying processes are more commonly used in food drying, as they allow for the preservation of food properties and nutrients.

[006] More specifically, the spouted bed drying method uses as its principle the interaction between a solid and a fluid, which are located inside a piece of equipment, Petition 870240111317, dated 12 / 30 / 2024, p. 16 / 37 3 / 17 named spouted bed. Spouted bed drying was developed for application in solid foods such as grains and seeds, and although research has already been conducted to evaluate the drying of pastes in this equipment, it is known that there are significant disadvantages to drying this type of material in spouted beds, such as the frequent instabilities in the fluid dynamic regime generated by feeding pastes, the occurrence of particle agglomeration phenomena, and the high accumulation of dust inside the drying chamber, which hinder, if not make impossible, the industrial use of the conventional spouted bed technique.

[007] As described in the document entitled “Influence of homogenization and drying on the thermal stability of microfibrillated cellulose. Polymer Degradation and Stability”, QUIÉVY, N. et al., some types of drying, especially those involving high temperatures, such as oven drying, promote degradation of the cellulose fiber, which can impair its properties.

[008] Given this scenario, it is possible to see that, despite the existence of various types of material drying methods and some options that promote greater preservation of this material, there is a major challenge in drying fibrillated cellulose so that there is no loss of fiber properties and so that it can be more easily transported, since the options are limited.

[009] There is, therefore, in the state of the art, a need to develop a drying process for fibrillated cellulose that does not degrade the fibers and that maintains their physicochemical properties, so that they are Petition 870240111317, dated 12 / 30 / 2024, page 17 / 37 4 / 17 properly incorporated into different applications, promoting advantageous properties for the applications of interest.

[0010] With the aim of drying fibrillated cellulose with minimal impairment of its mechanical properties, a method for drying cellulose in suspension using a spouted bed was developed in the present invention. The dried fibrillated cellulose obtained from this method exhibited advantageous physicochemical properties, even after redispersion, and proved to be a promising raw material for application in different products, mainly in thermoplastic composites. SUMMARY OF THE INVENTION

[0011] The present invention aims to provide a method for drying fibrillated cellulose that preserves its physicochemical properties, as well as a dried fibrillated cellulose with preserved properties, and the use of this fibrillated cellulose. The present invention also discloses a polymer composite composition comprising said fibrillated cellulose and the use of the composite composition.

[0012] Fibrillated cellulose is understood to be any cellulose that has undergone a fibrillation process, such as, but not limited to, nanofibrillated cellulose, microfibrillated cellulose, cellulose obtained by enzymatic, mechanical or chemical fibrillation, among other processes.

[0013] A first embodiment of the invention relates to the method of drying fibrillated cellulose, which Petition 870240111317, dated 12 / 30 / 2024, page 18 / 37 5 / 17 comprises the following steps: (a) prepare a suspension of fibrillated cellulose; (b) insert inert solid particles into the spouted bed equipment; (c) adjust the temperature inside the equipment in the range between 50 and 90°C, air flow between 0.7 and 2 m3 / min and pressure drop in the bed (ΔP) between 682.59 and 1291.52 Pa; (d) feed the spouted bed with the suspension obtained in step (a) at a feed flow rate of 6 to 8.6 mL / min; and (e) remove the fibrillated cellulose from the spouted bed.

[0014] A second embodiment of the invention relates to fibrillated cellulose dried by means of the spouted bed method, with properties preserved.

[0015] A third embodiment of the invention relates to the use of said dry fibrillated cellulose in different applications, such as application in thermoplastics, polymer composites, papers, cosmetics, paints, fiber cement, cement, household, resins, among other applications.

[0016] A fourth embodiment of the invention relates to a polymer composite composition comprising spouted-bed dried fibrillated cellulose, a polymer and a compatibilizing agent.

[0017] A fifth embodiment of the invention relates to the use of the polymer composite composition for application in thermoplastic parts via injection or thermoforming processes, such as automotive parts, rigid packaging for general applications, utensils. Petition 870240111317, dated 12 / 30 / 2024, page 19 / 37 6 / 17 domestic, logistics boxes or applications for the agricultural industry. BRIEF DESCRIPTION OF THE FIGURES

[0018] Figure 01 schematically illustrates the cyclical and ordered movement of particles in a conventional spouted bed.

[0019] Figure 02 represents the inert polymer for the fluid dynamic study in spouted bed drying, as per Example 1 of the present invention.

[0020] Figure 03 represents silica spheres of different diameters tested during drying, with a) having a smaller diameter and b) having a larger diameter.

[0021] Figure 04 represents redispersed fibrillated cellulose, after drying, homogeneous and without lumps. DETAILED DESCRIPTION OF THE INVENTION

[0022] The present invention relates to a method for drying fibrillated cellulose by spouting bed that preserves its physicochemical properties, as well as a dried fibrillated cellulose with preserved properties and the use of the fibrillated cellulose. The invention also relates to a polymer composite composition containing said spouted-bed dried fibrillated cellulose and to the use of said composition.

[0023] The fibrillated cellulose of the present invention can be understood as any cellulose that has undergone a fibrillation process, such as, but not limited to, nanofibrillated and microfibrillated cellulose. In a preferred embodiment, the fibrillated cellulose is microfibrillated cellulose.

[0024] Cellulose fibrillation processes can Petition 870240111317, dated 12 / 30 / 2024, page 20 / 37 7 / 17 can be carried out by mechanical, chemical or enzymatic means, preferably by mechanical means.

[0025] The fibrillated cellulose used in the present invention is in paste form.

[0026] The type of drying used in the method of the present invention is spouted bed drying. As can be seen in the diagram in Figure 01, the spouted bed is equipment consisting of a cylindrical drying chamber connected to a conical base, which has, at its lower end, a small orifice through which the spouted fluid is fed into the system.

[0027] The jet flow regime is established by the entry of a jet of fluid into a bed of particulate solids. After the fluid, usually composed of air, enters, the solid particles accelerate upwards, forming a diluted central channel where they exhibit high velocity. This region is called the jet flow region. Around the central channel, a dense bed of particles is present, moving against the upward airflow, tracing a parabolic trajectory in relation to the central region of the equipment. The region comprising this sliding bed of particles is called the annulus or annular region. The deceleration of the particles from the jet flow region occurs after they reach the surface of the bed (source region), resulting in their fall onto the annular region.

[0028] Finally, these particles will describe an annular trajectory back to the jet region, either after hitting the base of the bed (near the air inlet orifice) or through crossflow (at the jet-annulus interface). Petition 870240111317, dated 12 / 30 / 2024, page 21 / 37 8 / 17

[0029] The state of the art reveals that there are many difficulties in applying spouted bed drying to pasty products, however, surprisingly, the present invention reveals a new method for drying fibrillated cellulose in pasty form.

[0030] The method for drying fibrillated cellulose of the present invention comprises the following steps: (a) prepare a suspension of fibrillated cellulose; (b) insert inert solid particles into the spouted bed equipment; (c) adjust the temperature inside the equipment in the range between 50 and 90°C, air flow between 0.7 and 2 m3 / min and pressure drop in the bed (ΔP) between 682.59 and 1291.52 Pa; (d) feed the spouted bed with the suspension obtained in step (a) at a feed flow rate of 6 to 8.6 mL / min; and (e) remove the fibrillated cellulose from the spouted bed.

[0031] The fibrillated cellulose suspension from step a) has a solids content in the range of 0.5 to 3.5%, preferably 1% solids in water. Preparing the suspension with the desired solids content is necessary because the fibrillated cellulose resulting from the industrial process has a higher solids content, which makes inserting the sample into the equipment difficult. Therefore, it is necessary to prepare a suspension with a lower solids content.

[0032] In an optional embodiment of the invention, an agent is added to the fibrillated cellulose (FC) suspension. Petition 870240111317, dated 12 / 30 / 2024, page 22 / 37 9 / 17 carrier in a ratio of 1:0.125 to 1:0.3 (CF:agent), preferably 1.0:0.30. The carrier agent is selected from the group consisting of ionic salts (counter-ions), hydrocolloids (cationic and anionic xyloglucan derivatives), water-soluble chitosan, hydroxyethylcellulose and carboxymethylcellulose, preferably carboxymethylcellulose (CMC).

[0033] Carboxymethylcellulose (CMC) acts as a carrier agent, drying promoter, and stabilizer in the spouted bed process, resulting in greater efficiency. Furthermore, carboxymethylcellulose acts as a redispersion promoter, since it prevents the formation of irreversible bonds in the hydroxyl groups on the fiber surface, causing the dried fibrillated cellulose to exhibit behavior similar to that of undried fibrillated cellulose.

[0034] The inert particles of step b) are selected from the group of polystyrene (lenticular and crystal), PVC (compound and pure), silica spheres, preferably lenticular polystyrene.

[0035] For step c) to be performed, the temperature inside the spouted bed is adjusted to the range between 50 and 90°C, preferably 80°C, the spout air flow rate adjusted to the range between 0.7 and 2.00 m3 / min, preferably 1.1 m3 / min and the pressure drop in the bed (ΔP) between 682.59 and 1291.52 Pa, preferably 1255 Pa.

[0036] The feeding of the suspension into the spouted bed in step d) can be carried out via atomization or dripping into the spouted bed, preferably atomization at a flow rate of mL / min. Petition 870240111317, dated 12 / 30 / 2024, page 23 / 37 10 / 17

[0037] The removal of cellulose in step e) is done in the sample collector, being transported by the system's airflow. The cellulose paste gradually covers the surface of the inert material and, with the evaporation of water, the cellulose film, upon reaching a critical level, is removed by friction between the particles of the inert material and / or with the bed wall, and the resulting powder is transported by the airflow and directed to the cyclone which removes the powder from the sample collector.

[0038] Another embodiment of the invention relates to fibrillated cellulose dried after application of the drying method of the present invention. The dried fibrillated cellulose retains its characteristics and advantageous properties, such as maintaining its original rheological properties even after drying and redispersion, not exhibiting lumps and being easily redispersed.

[0039] The dry fibrillated cellulose of the present invention can be used for application in thermoplastics, polymer composites, papers, cosmetics, paints, fiber cement, cement, household products, resins, among other applications. Preferably, the use of fibrillated cellulose is for application in a polymer composite.

[0040] In one embodiment of the invention, a polymer composite composition is obtained, comprising: a) 2 to 8% of fluidized bed-dried fibrillated cellulose, preferably 8%; b) 86 to 96% polymer; and c) 2 to 6% of a compatibilizing agent, preferably 4%. Petition 870240111317, dated 12 / 30 / 2024, page 24 / 37 11 / 17

[0041] The polymers included in the composite composition may be selected from the group of polyethylene and polypropylene resins, polylactic acid (PLA), polybutylene succinate (PSA), polycaprolactone (PBS), preferably polypropylene.

[0042] The compatibilizing agents included in the composite composition may be selected from the group of maleic anhydride-grafted polypropylene (MAPP) or polypropylene oligomer, preferably a maleic anhydride-grafted polypropylene compatibilizing agent.

[0043] The resulting composition can be used for thermoplastic parts, obtained via injection or thermoforming, such as automotive parts, rigid packaging for general applications, household utensils, logistics boxes, or applications for the agricultural industry. EXAMPLES

[0044] The examples presented in the present invention are non-exhaustive, serve only to illustrate the invention and should not be used as a basis for limiting it. EXAMPLE 1

[0045] This example describes the drying method of the present invention.

[0046] The preparation of fibrillated cellulose was carried out from the formation of a suspension of bleached Kraft fibrillated cellulose from eucalyptus pulp containing 3.5% solids content diluted in deionized water to 1% solids content. 1 L of suspension was prepared and the samples were diluted under agitation. Petition 870240111317, dated 12 / 30 / 2024, page 25 / 37 12 / 17

[0047] The spouted bed was prepared with a solids load of 800g of lenticular polystyrene (PS) as inert material, as shown in Figure 02. Table 01 presents the physical characteristics of the lenticular polystyrene particles used: Table 01 - Physical characterization of lenticular polystyrene particles Material PS Lenticular Shape dp (mm)a 5.19 ±0.26 (Da 0.87 ± 0.03 pbuik (kg / rr)3)b 663.2 ± 4.6 Preal (kg / m3)b 1051.9 ± 1.2 ysv (N / m) x 103 32 ε If (%) 36.85 a) standard deviation; b) mean deviation

[0048] It was also possible to dry fibrillated cellulose using silica spheres with two different diameters, as shown in Figures 02 and 03, but in a different spouted bed drying system.

[0049] A study was carried out and a fluid dynamic curve of the lenticular PS was established. With the data from said curve, the air flow rate of the spouted bed for the experimental design was defined as 1.1 m3 / min, being 63% greater than the minimum spout flow rate (Qjm) to maintain stable spouting during the drying operation of the fibrillated cellulose suspension. Petition 870240111317, dated 12 / 30 / 2024, pp. 26 / 37 13 / 17

[0050] The suspension was fed by a digital peristaltic pump specifically designed for the equipment.

[0051] To maintain the suspension stable after dilution in deionized or distilled water, the suspension was kept under constant agitation using a mechanical mixer. The peristaltic pump transports the suspension to a double-fluid spray nozzle. The feed flow rate of the suspension was carried out in the range of 6 to 8 mL / min, preferably 6 mL / min for a drying temperature of 60 °C and 8 mL / min for a drying temperature of 80 °C.

[0052] The drying of the fibrillated cellulose suspension was carried out by atomization with an atomizing nozzle of 1.2 mm opening, atomizing air flow rate of 30 L / min and atomizing air pressure of 4 bar.

[0053] The spout bed temperature was adjusted to the range of 50 to 90 °C, preferably 80 °C for a suspension feed flow rate of 8 mL / min using atomization from the bottom of the spout chamber.

[0054] After being inserted into the spouted bed, the cellulose remains circulating in the bed for 10 minutes, forming a powder. The airflow transports this cellulose powder to the cyclone, where it is deposited in the sample collector. The cellulose pulp is continuously fed into the bed by atomization until all the suspension is gone and the material is completely dry. EXAMPLE 2

[0055] This example describes the viscosity characteristics of the fibrillated cellulose obtained Petition 870240111317, dated 12 / 30 / 2024, page 27 / 37 14 / 17 before drying and after drying and redispersion, all viscosity measurements described here were performed on a rheometer, oscillatory mode, cone-plate geometry, 50 rpm, 0.85 wt%.

[0056] The viscosity of fibrillated cellulose measured before the application of a drying method was 35-45 cPs. When dried by conventional drying and redispersion, the fibrillated cellulose showed a viscosity between 10-18 cPs, demonstrating a loss in the property, which does not allow for the formation of a homogeneous gel and, consequently, impairs the use of cellulose in some applications. After drying in a spouted bed and redispersion, the fibrillated cellulose again showed a viscosity of 35-45 cPs, promoting the formation of a homogeneous gel, without the formation of lumps, as shown in Figure 04.

[0057] These results prove the efficiency of the drying method of the present invention in maintaining the original properties of fibrillated cellulose, preventing its degradation and proving to be an excellent alternative. EXAMPLE 3

[0058] This example describes the application of dry fibrillated cellulose in a polymer composite composition.

[0059] For better control of particle size, the dry fibrillated cellulose was fragmented in an ultracentrifugal mill equipped with a 1 mm opening sieve, using a centrifugation range between 10000 and 15000 rpm, preferably 12000 rpm.

[0060] Polypropylene and a compatibilizing agent were used as the matrix for preparing the composites. Petition 870240111317, dated 12 / 30 / 2024, pp. 28 / 37 15 / 17 polypropylene grafted with maleic anhydride. For mixing the ingredients, 88% polymer, 4% compatibilizing agent, and 8% fibrillated cellulose were added to a mixer. The ingredients were premixed manually. In the mixer, the temperature range was adjusted to 140 to 180 °C, preferably 160 °C, with a mixing time range of 5 to 10 min, preferably 10 min, and a rotation speed range of 10 to 100 rpm, preferably 60 rpm.

[0061] The composite material was removed from the mixing chamber and used to produce parts using an injection molding machine, for the formation of thermoplastic parts. In the injection molding machine, the temperature range was set to 140 to 180 °C, preferably 160 °C, injection pressure from 200 to 800 bar, preferably 800 bar, and injection time from 10 to 15 seconds, preferably 15 seconds. EXAMPLE 4

[0062] This example presents the characterization and performance tests of the composites obtained from the composition of the present invention.

[0063] Tensile strength tests of the composites were carried out in accordance with ASTM D638 using an Instron EMIC 23-50 universal testing machine with a 1 kN load cell, a test speed of 10 mm / min and a grip distance of 25 mm.

[0064] The tensile test results show that the composite exhibits tensile strength values ​​closer to PP / MAPP.

[0065] The Young's modulus of the composition with 4% fibrillated cellulose presents the most similar results. Petition 870240111317, dated 12 / 30 / 2024, pp. 29 / 37 16 / 17 to the behavior of pure PP / MAPP. Deformation decreases as the amount of fibrillated cellulose in the composite increases, however, formulations with 2% fibrillated cellulose exhibit behavior closer to pure PP / MAPP.

[0066] Morphological tests were performed using a Tescan Veja 4 LMS scanning electron microscope; the samples were fractured in liquid nitrogen and subsequently coated with a thin layer of gold.

[0067] Morphology results show that fibrillated cellulose is well dispersed in the PP matrix, and the presence of the compatibilizing agent (MAPP) indicates improved adhesion of fibrillated cellulose to the polymer matrix as observed in the mechanical results.

[0068] Thermal analysis tests were performed using thermogravimetric analysis (TGA) with a TA Instruments Q50 thermal analyzer under a N2 atmosphere with a gas flow rate of 100 mL / min, a heating rate of 10 °C / min, and a temperature range of 30 to 700 °C, with samples weighing between 5 and 9 mg. Differential Scanning Calorimetry (DSC) was performed using a TA Instruments Q20 analyzer under a N2 atmosphere with a gas flow rate of 100 mL / min, a heating rate of 10 °C / min, and a temperature range of 25 to 200 °C. To eliminate the thermal history of the polymer, the first heating and cooling was performed, followed by heating under the same conditions and with a cooling rate of 10 °C / min.

[0069] The results of the thermal analysis show that the presence of fibrillated cellulose increases the maximum temperature. Petition 870240111317, dated 12 / 30 / 2024, page 30 / 37 17 / 17 degradation rate when compared to pure PP. The presence of cellulose particles delays the volatilization of products resulting from the breakdown of carbon-carbon bonds in the polymer matrix, increasing its thermal stability.

[0070] The presence of the compatibilizing agent (MAPP) leads to a decrease in the degradation temperature compared to pure PP, with the presence of fibrillated cellulose it was possible to observe an increase in the degradation temperature of the composite, increasing its thermal stability. Petition 870240111317, dated 12 / 30 / 2024, pages 31 / 37

Claims

1 / 3 CLAIMS 1. A method for drying fibrillated cellulose, characterized in that it comprises the steps of: (a) preparing a suspension of fibrillated cellulose; (b) inserting inert solid particles into the spouted bed equipment; (c) adjusting the temperature inside the equipment in the range between 50 and 90°C, air flow rate between 0.7 and 2 m3 / min and pressure drop in the bed (ΔP) between 682.59 and 1291.52 Pa; (d) feeding the spouted bed with the suspension obtained in step (a) at a feed flow rate of 6 to 8.6 mL / min; and (e) removing the fibrillated cellulose from the spouted bed.

2. Method according to claim 1, characterized in that the fibrillated cellulose suspension of step a) is prepared in the range of 0.5 to 3.5% solids in water, preferably 1% solids in water.

3. Method according to claim 1 or 2, characterized in that a carrier agent is optionally added to the suspension of step (a), in the range of fibrillated cellulose:carrier agent ratio of 1:0.125 to 1:0.3, preferably 1.0:0.30, wherein the carrier agent is selected from the group consisting of ionic salts (counter-ions), hydrocolloids (cationic and anionic xyloglucan derivatives), water-soluble chitosan, hydroxyethylcellulose and carboxymethylcellulose, preferably carboxymethylcellulose (CMC). Petition 870240111317, dated 12 / 30 / 2024, page 32 / 37 2 / 3 4. Method according to any one of claims 1 to 3, characterized in that the inert particles are selected from the group of polystyrene (lenticular and crystalline), PVC (compound and pure), silica spheres, preferably lenticular polystyrene.

5. Method according to any one of claims 1 to 4, characterized in that, in step c), the jet air flow rate is adjusted to the range between 0.7 and 2.00 m3 / min, preferably 1.1 m3 / min, and the pressure drop in the bed (ΔP) is between 682.59 and 1291.52 Pa, preferably 1255 Pa.

6. Method according to any one of claims 1 to 5, characterized in that the suspension is fed into the spouted bed in step d) via atomization or dripping into the spouted bed, preferably atomization at a flow rate of 8 mL / min.

7. Fibrillated cellulose, characterized by being obtained by the method defined in any one of claims 1 to 6, wherein the fibrillated cellulose has a viscosity between 35-45 cPs, after being dried in a spouted bed and redispersed.

8. Use of fibrillated cellulose defined in claim 7, characterized by being for application in thermoplastics, polymer composites, papers, cosmetics, paints, fiber cement, cement, household products, resins, among other applications.

9. Use of fibrillated cellulose according to claim 8, characterized by being preferably for application in a polymeric composite. Petition 870240111317, dated 12 / 30 / 2024, page 33 / 37 3 / 3 10. Polymer composite composition, characterized by comprising: a) 2 to 8% of fluidized bed-dried fibrillated cellulose defined in claim 7; b) 86 to 96% of polymer; and c) 2 to 6% of compatibilizing agent.

11. Composition according to claim 10, characterized in that the polymer is selected from the group consisting of polyethylene and polypropylene resins, polylactic acid (PLA), polybutylene succinate (PSA), polycaprolactone (PBS), preferably polypropylene.

12. Composition according to claim 10 or 11, characterized in that the compatibilizing agent is selected from the group consisting of maleic anhydride-grafted polypropylene (MAPP) or polypropylene oligomer, preferably a maleic anhydride-grafted polypropylene compatibilizing agent.

13. Use of the composition defined in any one of claims 10 to 12, characterized by the fact that it is for application in thermoplastic parts, such as, for example, automotive parts, rigid packaging for general applications, household utensils, logistics boxes or applications for the agricultural industry.

14. Use of the composition according to claim 13, characterized in that the thermoplastic parts are obtained via injection or thermoforming process. Petition 870240111317, dated 12 / 30 / 2024, pp. 34 / 37

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