PROCESS FOR MANUFACTURING ANTICORROSIVE ADHESIVE FILM, ANTICORROSIVE ADHESIVE FILM AND ITS USE

Description

1 / 26 PROCESS FOR MANUFACTURING ANTICORROSIVE ADHESIVE FILM, ANTICORROSIVE ADHESIVE FILM AND ITS USE FIELD OF THE INVENTION

[001] The present invention falls within the field of Inspection Technologies, Materials, Equipment and Corrosion, more precisely in the area of ​​polymeric materials applied to the anticorrosive protection of offshore and onshore metallic structures, and refers to anticorrosive adhesive films obtained by thermoplastic transformation processes (extrusion / thermoforming) using recycled raw materials, and designed to act as an anticorrosive and dielectric barrier on metallic substrates without the need for extensive prior surface preparation. FUNDAMENTALS OF THE INVENTION

[002] Due to the complexity of the climatic conditions to which metal structures on offshore exploration platforms are exposed, including constant sun exposure, winds and salt spray, the paints currently used to coat the surfaces need to meet strict requirements.

[003] Currently, the process of protecting metal structures exposed to severe weather conditions on oil platforms is done through multi-layered, high-thickness painting. Beyond the cost of the paints, there are also the costs of surface preparation, machinery, and labor. There is also the operational cost if the area to be painted needs to undergo a technical shutdown, partially paralyzing operations, which always represents losses in productivity. Furthermore, the layers require time between coats, which can represent hours or even days of unproductive time.

[004] Companies like Petrobrás, for example, have pre-established standards to define the characteristics that paints must possess to meet the proposed anti-corrosion purpose. Petition 870260016621, dated 23 / 02 / 2026, page 42 / 79 2 / 26 Strict, yet necessary, criteria limit market availability and increase prices, making this raw material expensive for industrial operations.

[005] For proper adhesion of the paint layers, especially the first layer, prior surface preparation is necessary, which requires time, machinery, and human labor. The time required for prior surface preparation and the time required for painting must be added to the time between coats. Depending on the manufacturer, the time between each coat can exceed 16 hours (25 °C), which can represent significant losses, especially if a technical shutdown is necessary on site.

[006] The technology presented in this invention offers potential benefits for surface protection. The adhesive films are delivered to companies in roll form, with customizable dimensions. Application can be performed by anyone with minimal training. The adhesive technology allows application to various surfaces, regular or irregular, without the need for prior preparation. As application is virtually instantaneous, technical downtime can be avoided. No additional coats are required as the adhesive already has all the necessary layers. STATE OF THE ART

[007] Document CN102850781B describes a polymer composition based on a PET / PA6 blend reinforced with glass fiber and specific additives, including antioxidants, lubricants, chain extenders, and flame retardants, as well as a method for its preparation. The main objective is to obtain a flame retardant using recycled PET (from bottles) and PA6, processed by twin-screw extrusion and granulation. The typical formulation involves proportions of 10-60 parts PET and 30-80 parts PA6, plus 5-40 parts glass fiber and additives. Petition 870260016621, dated 23 / 02 / 2026, page 43 / 79 3 / 26 functional. The process includes drying, high-speed mixing, extrusion at temperatures between 190-260 °C and subsequent granulation for injection molding.

[008] Both CN102850781B and the present invention deal with recycled PET / PA6 blends and the use of extrusion as a processing route. The document shows that the combination of these two polymers is known and used to improve mechanical and thermal properties, which technically brings the solutions closer together. The similarity lies in the basic PET / PA6 composition and the use of extrusion, as well as the environmental concern with the reuse of PET.

[009] However, document CN102850781B focuses on the production of granules for molding, not addressing adhesive films. Furthermore, its formulation includes fiberglass and flame retardants, while the present invention does not use reinforcements or complex additives, prioritizing flexibility and adhesion. Another point is that there is no mention of an acrylic adhesive layer, nor of direct application on metallic surfaces for anti-corrosion protection. Finally, the functional scope also differs: CN102850781B seeks structural resistance and flame retardant properties, while the present invention aims to offer an anti-corrosion and dielectric barrier with quick and simplified application.

[010] Document CN104195671B describes a technology for the production of sheath-core type PA6-PET composite monofilaments with diameters between 0.05 and 5 mm, high mechanical strength (^3 CN / dtex), elongation at break between 15% and 35%, and controlled thermal shrinkage rate (6-10% after treatment at 160 °C). The composition is based on PA6 and PET, varying between 10% and 90% for each component, with PA6 being the outer layer (sheath) and PET the core. The process involves melt extrusion, liquid cooling, stretching, and thermal fixation, with specific parameters such as temperatures of Petition 870260016621, dated 23 / 02 / 2026, page 44 / 79 4 / 26 melting point (PA6: 250-270 °C; PET: 275-295 °C), stretch ratio (2-20) and use of liquid bath with additives (sodium bisulfite solution, polyethylene wax and dioctadecyl sulfide). The objective is to obtain fibers with excellent physical performance and thermal stability for diverse industrial applications.

[011] Both CN104195671B and the present invention exploit the PET / PA6 combination and the use of extrusion as a processing route. The document demonstrates that the miscibility and thermal stability of the PET / PA6 blend are known and applied in technical products, which reinforces the viability of the present solution. The similarity lies in the polymeric composition (PET and PA6) and the use of extrusion to form a solid body with specific properties.

[012] However, document CN104195671B focuses on the production of structural monofilaments, without any relation to adhesive films. Furthermore, there is no reference to the presence of an acrylic adhesive layer nor to the anti-corrosion or dielectric function, central characteristics of the present invention. While CN104195671B prioritizes mechanical resistance and thermal shrinkage control, the proposed solution seeks to offer immediate anti-corrosion protection and direct application to metallic surfaces without the need for prior preparation. Finally, the process described in CN104195671B involves steps such as liquid cooling and stretching, differing substantially from current technology, which uses calendering and in-line adhesive application to ensure practicality and efficiency.

[013] Document CN117209821A describes a method for producing a recycled polyester-based thermoplastic film with waterproof and moisture-permeable properties, using a blend composed of TPEE (thermoplastic polyester elastomer) in a major proportion (70-90 parts), recycled PET (6-20 parts) and additives (10-15 parts). The process takes place in a casting machine equipped with specific sections. Petition 870260016621, dated 23 / 02 / 2026, p. 45 / 79 5 / 26 (barrel, screen change, elbow and connection), operating at temperatures between 245 °C and 270 °C. The technology exploits the rigidity and high melting point of PET to reinforce the mechanical strength of the TPEE film, maintaining its moisture permeability, while expanding the use of recycled PET. Thermal tests (DSC) demonstrate an increase in the film's melting point with the addition of PET, and physical tests indicate that, although moisture permeability decreases with a higher PET content, it remains acceptable even with 30% PET, while tensile strength increases.

[014] Both CN117209821A and the present invention deal with the production of polymeric films with recycled PET and use extrusion / thermoforming processes. The document confirms that the use of recycled PET in technical films is a known practice and that its incorporation improves mechanical properties, which reinforces the technical feasibility of the proposed solution.

[015] However, document CN117209821A uses TPEE as the main matrix, while the present invention employs a blend of r-PET and r-PA6, focusing on sustainability and functional performance. Furthermore, the objective of CN117209821A is to ensure impermeability and moisture permeability control, with no mention of corrosion protection or the creation of a dielectric barrier, which are central characteristics of the proposed technology. There is also no reference to the presence of an acrylic adhesive layer or the possibility of direct application to metallic surfaces without prior preparation. Finally, the process described in CN117209821A involves casting in a casting machine with specific steps, differing completely from the approach of the present invention, which uses calendering and in-line adhesive application to obtain a flexible, ready-to-use film.

[016] Document US10632725B2 describes a method for producing oven plates coated with a polymer resistant to Petition 870260016621, dated 23 / 02 / 2026, page 46 / 79 6 / 26 heat, as well as food trays and packaging that withstand heating in conventional ovens or microwaves. The solution consists of extruding a prefabricated PET film (or derivatives such as PETG) onto a fibrous base, using an extruded polyamide (PA) adhesive layer between the film and the substrate. The process allows the PET film to be pre-oriented by stretching, promoting crystallization and improving mechanical properties and gas barrier. Furthermore, the film can be multilayered, including combinations of PET and PETG to optimize moldability and strength, and can receive additional treatments (metallization, corona) to improve adhesion and functionality. The PA adhesive layer can be composed of special polyamides, such as PA6, MXD6, or HBPA, ensuring high barrier and heat resistance. The typical weight of the PET film ranges from 10-30 g / m2, while the PA layer ranges from 3-15 g / m2.

[017] Both US10632725B2 and the present invention explore the combination of PET and polyamide and the use of extrusion to join layers, aiming at specific functional properties. The aforementioned document demonstrates that the PET / PA association to create thermal and structural barriers is known, which technically approximates the solutions.

[018] However, document US10632725B2 deals with oven plates and food packaging, without any relation to adhesive films aimed at anti-corrosion protection. Furthermore, there is no mention of the presence of a water-based acrylic adhesive layer nor the possibility of direct application to metallic surfaces without prior preparation, which are central characteristics of the present invention. The objective of US10632725B2 is to offer heat resistance and a barrier for food, while the proposed technology seeks to guarantee anti-corrosion and dielectric protection in harsh industrial environments. Finally, the product described in US10632725B2 results in a rigid structure laminated onto cardboard, differing completely from the concept. Petition 870260016621, dated 23 / 02 / 2026, page 47 / 79 7 / 26 current, which consists of a flexible film supplied in rolls for quick and simplified application.

[019] The document in the name of Chiou et al. (2022), entitled “Effects of Environmental Aging on The Durability of Wood-Flour Filled Recycled PET / PA6 Wood Plastic Composites (Chiou YC, Shen MY, Chiang CL, Li YL, Lai WM. Effects of Environmental Aging on the Durability of Wood-Flour Filled Recycled PET / PA6 Wood Plastic Composites. Journal of Polymers and the Environment, v. 30, p. 1300-1313, 2022) investigates the effects of environmental aging on the durability of wood-plastic composites (WPC) produced from recycled blends of PET (rPET) and polyamide-6 (rPA6), reinforced with recycled wood flour (POE-g-MA and MBS).Different rPET / rPA6 ratios (60 / 40, 50 / 50, and 40 / 60) were tested, evaluating tensile strength, flexural strength, impact strength, and thermal stability before and after 30 days of exposure to UV radiation, humidity, and temperature cycles. The results indicated that the 60 / 40 formulation showed better thermal performance and stability after aging, while the 40 / 60 formulation had higher initial mechanical properties but degraded more under weathering. The study also showed that temperature, humidity, and load significantly influence creep, with greater deformation under severe conditions (55 °C and 90% RH).

[020] Furthermore, Chiou et al. (2022) confirms the technical feasibility of the rPET / rPA6 blend and explores its performance under critical conditions, something essential for anticorrosive applications in aggressive environments; in addition to showing that the combination of recycled PET / PA6 is known and studied to improve mechanical and thermal properties, which conceptually approximates the proposed solution. Petition 870260016621, dated 23 / 02 / 2026, page 48 / 79 8 / 26

[021] However, Chiou et al. (2022) discusses composites reinforced with lignocellulosic fillers, such as wood flour, while the present invention consists of a multilayer adhesive film without any type of filler, prioritizing flexibility and adhesion. Furthermore, the focus of Chiou et al. (2022) is on structural applications for civil construction, differing entirely from the objective of the present invention, which seeks anti-corrosion and dielectric protection for metallic surfaces. There is no mention of the presence of an acrylic adhesive layer nor the possibility of direct application on metallic substrates without prior preparation. Finally, the final format described in Chiou et al. (2022) is that of molded parts, contrasting with the proposed solution, which is presented as flexible coils for quick and simplified application in industrial environments.

[022] The document in the name of Luo et al. (2024), entitled “Recycled PET / PA6 Fibers from Waste Textile with Improved Hydrophilicity by In-Situ Reaction-Induced Capacity Enhancement (Luo LB, Chen R, Lian YX, Wu WJ, Zhang JH, Fu CX, Sun XL, Xiao LR. Recycled PET / PA6 Fibers from Waste Textile with Improved Hydrophilicity by In-Situ Reaction-Induced Capacity Enhancement. Polymers, v. 18, n. 8, e.1052, 2024), presents an approach to textile recycling, exploring the production of fibers from blends of recycled PET (rPET) and recycled polyamide-6 (rPA6) with improved properties through in situ reaction. The study demonstrates that small amounts of rPA6 (up to 10%) incorporated into rPET during the melting and spinning process increase the compatibility between the phases, thanks to the formation of ester-amide exchange copolymers.This modification improves the hydrophilicity of the fibers (reducing the contact angle from 91.3° to 80.3°), raises the crystallization temperature of PET, and promotes better dispersion of PA6 in the matrix, resulting in fibers with greater elongation at break (up to 17.48%) and adequate strength for textile applications. The work also analyzes... Petition 870260016621, dated 23 / 02 / 2026, page 49 / 79 9 / 26 thermal, rheological and structural properties, confirming that the presence of PA6 reduces melt viscosity, improves fluidity and maintains stability for spinning processes.

[023] The aforementioned document reinforces the technical feasibility of the rPET / rPA6 blend and highlights compatibility mechanisms that guarantee functional performance. Both Luo et al. (2024) and the present invention share the premise of using recycled PET and PA6 to create a material with optimized properties, exploring thermal and extrusion processes.

[024] However, Luo et al. (2024) focuses on the production of textile fibers, emphasizing properties such as elongation and hydrophilicity, while the present invention aims to develop anti-corrosive adhesive films for application on metallic surfaces. Furthermore, there is no mention of the presence of an acrylic adhesive layer or the possibility of direct application without prior preparation, central characteristics of the proposed technology. Another relevant point is the final format: Luo et al. (2024) describes continuous yarns intended for textile applications, whereas the present invention consists of flexible film reels with a controlled thickness between 50 and 80 μm, designed to ensure quick and efficient application in industrial environments.

[025] The document in the name of Malvessi (2023), entitled “Production of heat-shrinkable films from recycled multilayer polyethylene and polyamide packaging (Malvessi DS. Production of heat-shrinkable films from recycled multilayer polyethylene and polyamide packaging. 66f. Monograph (Materials Engineering) - Federal University of Santa Catarina, Blumenau, 2023), presents a study focused on the recycling of flexible multilayer packaging, which is traditionally difficult to reuse due to the presence of incompatible polymers, such as PE and PA. Petition 870260016621, dated 23 / 02 / 2026, p. 50 / 79 10 / 26 with maleic anhydride (PE-g-MA) as a compatibilizer, both in the original film formulation and in the recycling process, to improve phase dispersion and allow the production of heat-shrinkable films with recycled material (PIR = Post-Industrial Recycled). Thermal (DSC), mechanical (tensile, drying modulus, perforation, delamination), oxygen permeability, and degree of shrinkage properties were evaluated. The results indicated that increasing the amount of adhesive did not compromise the properties of the multilayer films and that the excess adhesive acted as a compatibilizer, enabling recycling. Heat-shrinkable films produced with up to 20% PIR showed adequate performance, without significant loss of strength or shrinkage capacity, demonstrating the technical and environmental viability of the proposal.

[026] Additionally, Malvessi (2023) directly addresses the compatibility of PE / PA systems to enable recycling and maintain functional properties, a challenge similar to that faced in the formulation of anticorrosive films with polymer blends. Both the aforementioned document and the present invention explore strategies to improve the interaction between immiscible polymers and ensure mechanical stability and processability after recycling or modification.

[027] However, Malvessi (2023) addresses heat-shrinkable packaging intended for the food sector, while the present invention aims to develop anti-corrosive adhesive films for application on metallic surfaces. Furthermore, Malvessi (2023) focuses on the recycling of industrial waste and formulation with PIR, without any mention of creating anti-corrosive or dielectric barriers. There is also no reference to the presence of a water-based acrylic adhesive layer or the possibility of direct application to metallic substrates without prior preparation. Finally, the final format described in Malvessi (2023) is a film intended for packaging, differing Petition 870260016621, dated 23 / 02 / 2026, page 51 / 79 11 / 26 completely of the proposed solution, which consists of flexible technical coils for industrial maintenance, ensuring quick and efficient application in harsh environments.

[028] The document in the name of Saidi et al. (2018), entitled “Development of anticorrosive coatings using disposable waste material” (Saidi NM, Shafaamri AS, Ma IAW, Kasi R, Balakrishran V, Subramaniam R. Development of anticorrosive coatings using disposable waste material. Pigment & Resin Technology, v. 47, n. 6, p. 478-484, 2018), describes the development of anticorrosive coatings using disposable waste, specifically recycled PET bottles dissolved by glycolysis and incorporated into an epoxy resin matrix, cured with polyamide. The study highlights that PET, in addition to being low-cost and exhibiting low permeability to gases and solvents, improves the adhesion and barrier properties of the coating.Formulations with different proportions of PET (5% to 25%) were prepared and evaluated for adhesion (pull-off and cross-hatch tests), gloss, wettability (contact angle), and corrosion resistance by electrochemical impedance spectroscopy (EIS) after immersion in saline solution for 30 days. The results indicated that the formulation with 10% PET showed the best overall performance, with greater corrosion resistance and better adhesion, although excessive increase in PET reduced gloss and mechanical strength.

[029] Both Saidi et al. (2018) and the present invention explore the use of recycled PET to create anti-corrosion barriers, taking advantage of its chemical and structural properties. This research reinforces the technical feasibility of using PET as a functional component in protective coatings, which can be interpreted as an indication that the idea of ​​employing recycled PET for corrosion protection is already known.

[030] Meanwhile, Saidi et al. (2018) describes Petition 870260016621, dated 23 / 02 / 2026, p. 52 / 79 12 / 26 liquid coatings applied by brush and cured in situ, while the present invention proposes multilayer adhesive films supplied in rolls for quick and simplified application. Furthermore, the formulation presented in Saidi et al. (2018) is based on epoxy combined with polyamide and dissolved PET, differing completely from the solid blend of r-PET / r-PA6 associated with a water-based acrylic adhesive layer used in the present invention. The process is also distinct: Saidi et al. (2018) involves chemical curing and film formation by reaction, whereas the proposed technology uses calendering and industrial lamination to ensure uniformity and efficiency. Finally, the focus of the document is on adhesion and electrochemical resistance, without considering essential aspects of the present solution, such as controlled thickness between 50 and 80 μm, flexibility, and direct application on metallic surfaces without prior preparation.

[031] The document in the name of Shouyun Zhang (2023), entitled “Characterization and compatibility of bio-based PA56 / PET” (Shouyun Z. Characterization and compatibility of biobased PA56 / PET. E-polymers, v. 23, n.1, p. 1-4, 2023), analyzes in detail the properties and compatibility between bio-based polyamide PA56 and polyethylene terephthalate (PET), focusing on textile applications. The study demonstrates that PA56 exhibits excellent moisture absorption, anti-electrostatic properties, good dyeability and softness, while PET stands out for its permeability, breathability and shape retention. Solubility tests, thermodynamic analyses, DMA, DSC, XRD and SEM were performed to evaluate the miscibility of PA56 / PET blends. The results indicated that the difference in solubility parameters (Δδ ~ 4.18) and enthalpy of mixing values ​​(ΔHm) reveals low compatibility, especially when the proportion of PA56 exceeds 20%.At lower concentrations (up to 15%), there is some compatibility in the amorphous and crystalline regions, but above 30% two compatibility zones emerge. Petition 870260016621, dated 23 / 02 / 2026, page 53 / 79 13 / 26 glass transitions and two melting peaks, confirming phase separation. SEM images show a typical structure of immiscible systems, with PA56 particles dispersed in the PET matrix. The study concludes that, for practical applications, it would be necessary to resort to techniques such as bicomponent spinning to take advantage of the complementary properties without compromising the integrity of the material.

[032] Furthermore, Shouyun Zhang (2023) directly addresses the issue of compatibility between PET and polyamides, a central theme in the formulation of anticorrosive films based on recycled PET / PA6. He provides scientific evidence that PET / polyamide systems tend to be immiscible, requiring compatibilization to ensure adequate properties. This reinforces the importance of the adhesive layer or compatibilizing agents in the present invention.

[033] However, Shouyun Zhang (2023) addresses the use of bio-based polyamide PA56 in textile applications, while the present invention employs a blend of r-PET and r-PA6 to develop anti-corrosive and dielectric films aimed at protecting metallic surfaces. Furthermore, there is no mention of the presence of a water-based acrylic adhesive layer nor the possibility of direct application without prior preparation, central characteristics of the proposed technology. Another relevant point is the functional scope: Shouyun Zhang (2023) focuses on fibers and fabrics, while the present invention defines a technical film with a controlled thickness between 50 and 80 μm, supplied in rolls for quick and efficient application in harsh industrial environments.

[034] That paper in the name of Yan et al. (2019) entitled “Polyamide 6 (PA6) / Polyethylene terephthalate (PET) Blends with Gradient and Encapsulation Structure Developed by Injection Molding” (Yan Y, Huang YH, Wang Y, Xiao ZC, Yang MB. Polyamide 6 (PA6) / Polyethylene terephthalate (PET) blends with terephthalate (PET) blends gradient Petition 870260016621, of 23 / 02 / 2026, p. 54 / 79 This article, titled "14 / 26 and encapsulation structure developed by injection molding. Polymer, v. 180, e. 121679, 2019," presents a study on injection-molded blends of polyamide 6 (PA6) and polyethylene terephthalate (PET), aiming to create a gradient and encapsulated structure capable of improving chemical resistance without compromising the mechanical properties of PA6. The research demonstrates that, during injection molding, the PET phase migrates to the region near the surface, forming an encapsulating layer that protects the PA6 matrix against aggressive solvents. Factors such as viscosity ratio between components and injection speed were analyzed, concluding that the formation of the structure depends more on the rheological properties of the system than on the processing speed.Microscopy (SEM, POM), FTIR and mechanical tests confirmed that the encapsulated structure preserves the ductility of PA6 and significantly increases its chemical resistance, especially in samples with 20% PET.

[035] Furthermore, Yan et al. (2019) directly addresses the PET / polyamide combination to create protective barriers, exploring concepts of phase migration and surface encapsulation to improve chemical resistance — a similar objective to the proposed solution for anticorrosive protection.

[036] However, Yan et al. (2019) describes injection-molded parts with a gradient structure, while the present invention proposes multilayer adhesive films supplied in rolls for quick and simplified application. Furthermore, there is no mention of the presence of a water-based acrylic adhesive layer nor the possibility of direct application to metallic substrates without prior preparation, essential characteristics of the proposed solution. The focus of Yan et al. (2019) is on the chemical resistance of structural parts, differing completely from the anti-corrosive and dielectric function aimed at industrial maintenance that defines the current invention. Finally, the process employed in Yan et Petition 870260016621, dated 23 / 02 / 2026, page 55 / 79 15 / 26 al. (2019) is based on injection with viscosity control, whereas the technology presented here uses calendering and industrial lamination to obtain thin films with controlled thickness between 50 and 80 μm, ensuring flexibility and operational practicality.

[037] Thus, unlike the prior art, the present invention describes a multilayer adhesive film based on recycled PET / PA6 with a water-based acrylic adhesive layer for direct application on metallic substrates without prior preparation, nor does it suggest the integration of this configuration with anti-corrosion and dielectric functions, supplied in flexible rolls with controlled thickness for rapid application in harsh industrial environments. SUMMARY OF THE INVENTION

[038] The present invention aims to provide anti-corrosion adhesive films made of a polymer blend of recycled poly(ethylene terephthalate) (r-PET) and recycled polyamide-6 (r-PA6), processed by extrusion in a flat die head and thermoforming in calenders, followed by the application of a water-based acrylic adhesive layer and a silicone protective liner. The preferred blend composition is 70% r-PET and 30% r-PA6, with variations between 90 / 10 and 50 / 50 according to flexibility and moldability requirements. The film has a typical thickness between 50 and 80 μm, an average basis weight of around 150 g / m2, and dielectric properties that provide a barrier to electrical conduction.Laboratory tests (EIS, climatic action chambers, natural atmospheric exposure for 8 months, adhesion, impact and immersion) demonstrate anti-corrosion performance equivalent to or superior to conventional systems, acting as a sealant / insulator in areas with paint defects and allowing for quick application, without multiple coats and without complex surface preparation. The product is supplied in coils, with customizable dimensions, and uses 100% recycled raw materials, aligning with... Petition 870260016621, dated 23 / 02 / 2026, pp. 56 / 79 16 / 26 Circular Economy and ESG guidelines. The films produced are used as an anti-corrosion and dielectric barrier on metallic substrates without the need for extensive prior surface preparation. BRIEF DESCRIPTION OF THE FIGURES

[039] Figure 1 illustrates the extrusion, thermoforming and winding system of r-PET / r-PA6 films by means of the feeder components (1), extruder (2) with two co-rotating screws, flat die (3), calenders (4) with cooling and winder (5), showing the continuous flow from the mixing and melting of the thermoplastics to the formation and packaging of the film in roll form.

[040] Figure 2 shows a prototype of the anticorrosive adhesive glue application machine, consisting of a rotary system in which the film produced via extrusion is unwound, receives a water-based acrylic glue applied with a thickness of 50 micrometers on one of the faces, followed by the application of liner (silicone-coated paper) and rewinding for delivery in the final shape.

[041] Figure 3 presents a thermogravimetric analysis (TGA) graph showing the mass loss curves of PET, PA6, and their mixtures containing 20% ​​PA6 or LDPE, in opaque and transparent versions. The curves show the thermal stability of the materials up to approximately 350 °C, followed by the onset of thermal degradation between 380 °C and 420 °C, allowing comparison of the thermal behavior and resistance to decomposition of the formulations.

[042] Figure 4 presents a differential scanning calorimetry (DSC) graph, showing the DSC curves of PET, PA6, and their mixtures with 20% PA6 or LDPE samples, in opaque and transparent versions, highlighting the melting and recrystallization events characteristic of each polymer. The observed thermal peaks allow the identification of the transitions. Petition 870260016621, dated 23 / 02 / 2026, pp. 57 / 79 17 / 26 endothermic and exothermic reactions of the formulations and evaluate the possible interactions between the polymeric phases.

[043] Figure 5 shows the electrochemical impedance spectroscopy for the standardized intact paint coating (top) and for the coating with the adhesive film (bottom). At the same frequency (10-2Hz), the impedance modulus is higher for the coating with adhesive film than for the intact paint, which indicates greater resistance to the passage of electric current and, consequently, greater insulation capacity, which proves the ability of the film to reduce the electrochemical phenomena of corrosion.

[044] Figure 6 shows samples after 25 exposure cycles in climatic chambers, with the sample on the left having the adhesive film applied and the sample on the right without protection.

[045] Figure 7 shows samples after 8 months of exposure to natural weathering, with the sample on the left having the adhesive film applied and the sample on the right without protection.

[046] Figure 8 shows the unrestricted linear shrinkage for the 100% r-PET and 80% r-PET + 20% r-PA6 films determined between 50 °C and 100 °C. At 50 °C and 60 °C, neither the 100% rPET film nor the 80% r-PET + 20% r-PA6 film showed shrinkage. However, from 70 °C onwards, the 100% r-PET film began to show shrinkage (wrinkling), with shrinkage values ​​increasing with increasing temperature. The 80% r-PET + 20% r-PA6 film began to show linear shrinkage only from 80 °C onwards, with shrinkage increasing with increasing temperature from this point. The maximum unrestricted linear shrinkage achieved at 100 °C for both the 100% r-PET and 80% rPET + 20% r-PA6 films was 0.1 mm and 0.05 mm, respectively. These results indicate that the 100% r-PET film is stable to abrupt temperature changes up to 60 °C and the 80% r-PET + 20% r-PA6 film is stable up to 70 °C, indicating, once again, that the incorporation Petition 870260016621, dated 23 / 02 / 2026, pp. 58 / 79 Using 18 / 26 of r-PA6 for the production of the r-PET / r-PA6 blend improved the final quality of the film. DETAILED DESCRIPTION OF THE INVENTION

[047] The present invention relates to anti-corrosion adhesive films made of a polymer blend of recycled poly(ethylene terephthalate) (r-PET) and recycled polyamide 6 (r-PA6), produced mechanically by combining extrusion with thermoforming on a flat die followed by a system of mechanical calenders, followed by the application of a water-based acrylic adhesive layer and a silicone protective liner. The process for manufacturing the films comprises the following steps: (a) Preparation of raw materials: drying of r-PET (150 °C) and r-PA6 (80 °C) pellets for 24 h to remove moisture; (b) Simultaneous feeding (by separate feeders) of r-PET and r-PA6 into the extrusion blocks; (c) Co-rotating extrusion: simultaneous feeding of polymers (r-PET, with a grain size between 1.80 and 2.50 g / 100 grains and r-PA6, with a grain size between 1.00 and 1.20 g / 100 grains) into the extruder equipped with two co-rotating helical screws (16 mm), promoting fusion and homogenization of the blend; (d) Flat die thermoforming: shaping the molten material into a film with an adjusted thickness (50-80 μm); (e) Controlled cooling: passage through chilled calenders with a closed circuit of water with additive cooling (heat exchanger), ensuring dimensional stability; (e) Initial winding: packaging the film into rolls for the subsequent step; (f) Unwinding and application of the adhesive layer: deposition of water-based acrylic adhesive (~50 μm) on one side of the film, followed by lamination with protective silicone paper (liner); and Petition 870260016621, dated 23 / 02 / 2026, pp. 59 / 79 19 / 26 (g) Final winding: obtaining the finished product in rolls ready for transport and application.

[048] In addition to the polymer blend of recycled poly(ethylene terephthalate) (r-PET) and recycled polyamide 6 (r-PA6), blends of r-PET with r-LDPE (low-density polyethylene), r-HDPE (high-density polyethylene), and r-PP (polypropylene) are also used. These blends have similar processing and protective barrier properties.

[049] The steps listed will be described in more detail below.

[050] The thermoplastic polymers used, poly(ethylene terephthalate) (PET), and polyamide-6 (PA6) are 100% recycled, PET from plastic packaging and polyamide-6 from clothing and general-use fabrics.

[051] The r-PET repeat structure has a benzene aromatic ring, whose structure allows free electron migration (which gives the structure high stability), in addition to having 6 carbon atoms with sp2 hybridization, which results in a trigonal planar geometry, making r-PET a rigid and inflexible structure.

[052] To increase its flexibility, a blend (polymer-polymer mixture) is produced by adding polyamide-6, a polymer that has strong hydrogen bonds between the amide groups (-CONH-), creating high cohesive energy density and intermolecular attraction. These hydrogen bond networks can reorganize and absorb impact energies, unlike PET whose aromatic rings restrict chain movement. The incorporation of a polyamide-6 fraction into PET allows the production of morphologically fine dispersions that improve film performance through amide-ester exchange during the melt-coupling process, creating copolymer bonds that stabilize the interface between the phases, improving the flexibility of PET and producing films with high malleability that can be applied to surfaces with the Petition 870260016621, dated 23 / 02 / 2026, pp. 60 / 79 20 / 26 plus various geometries.

[053] The r-PET and PA6 pellets were previously dried in an oven at 150 °C and 80 °C, respectively, for 24 h prior to extrusion. Depending on the desired application, due to the required flexibility, the mixture may contain fractions ranging from 90% PET and 10% polyamide-6, up to 50% of each polymer, ensuring the good anti-corrosion properties offered by PET. To coat an irregular surface, the film is expected to be moldable and flexible.

[054] Thus, film thickness is a parameter of great relevance for its suitability for different purposes. Thinner films tend to be more flexible and have greater moldability. As an example, the 100% r-PET film showed greater thickness than the 80% r-PET + 20% PA6 film. This result corroborates the positive influence of adding PA6 to r-PET, as it reduced its thickness and increased its moldability, making the films more suitable for irregular surfaces and more complex geometries.

[055] As observed in Figure 1, the feeders are used to feed the r-PET thermoplastic pellets, with a grain size between 1.80 and 2.50 g / 100 grains, and r-PA6, with a grain size between 1.00 and 1.20 g / 100 grains, into the extruder, which is equipped with two 16 mm co-rotating screws intended for homogenizing the molten thermoplastics.

[056] The extruder consists, in summary, of a circular barrel with two co-rotating helical screws responsible for transporting and mixing the polymers. Throughout the barrel, there is heating provided by thermal resistors to promote the melting of the thermoplastics. At the exit of the extruder barrel, at the end of the transport by the co-rotating screws, a flat die head is fitted, responsible for shaping (thermoforming) the r-PET / r-PA6 blend.

[057] The extrusion temperature occurs in a range between Petition 870260016621, dated 23 / 02 / 2026, pp. 61 / 79 21 / 26 200 °C and 250 °C. The flat die represents the extrusion outlet where the homogenized liquid material is shaped into a film with a predefined thickness (between 50 and 80 micrometers) through mechanical adjustment of the part.

[058] Immediately next to the flat die, the first roll of the calender system is positioned, with an internal cooling system to promote heat exchange between the fluid and the thermoformed thermoplastic. The fluid (without direct contact with the film) consists of distilled water with added anti-corrosive and anti-algae agents, being recirculated in a closed cycle by a chiller. After film formation by the flat die, distribution, thickness correction and cooling by the calender rolls, the film is continuously transported to a winding cylinder to be packaged in roll form with customizable dimensions.

[059] For every kilogram of feed, 920 grams of product are obtained. The loss of 80 grams of material is due to the adjustments needed to start the process, which are reduced with increasing production time.

[060] Subsequently, the film is unwound while receiving an adhesive layer, and then rewound into its final delivery form. This gluing step is performed on equipment designed during the development of the present invention, which consists of a rotary system in which the extruded film is unwound at one end, a water-based acrylic adhesive is applied with a thickness of 50 micrometers to one face of the film, and a liner is applied over the adhesive, as illustrated in Figure 2.

[061] The quality of extruded and thermoformed films can be assessed using various techniques. Through thermogravimetry and differential calorimetry, it is possible to identify whether the blend (polymer mixture) between r-PET and r-PA6 exhibits miscibility and is thermodynamically stable. Petition 870260016621, dated 23 / 02 / 2026, pp. 62 / 79 22 / 26 as illustrated in Figure 4. These parameters attest that the film presents satisfactory mechanical, physical and chemical characteristics to suit the applications proposed for them.

[062] Using infrared spectroscopy, it is possible to verify the intensity of the characteristic stretch peaks that represent the organic bonds that make up both polymers. It is also possible to estimate, using this technique, the loss due to thermal degradation caused in the mechanical extrusion process. The less loss of characteristics after the processing steps, the better the physical, mechanical and chemical characteristics of the films produced.

[063] Other standardized tests allow comparison of the quality and strength of prepared films, such as density (NBR 11936), tensile strength (ASTM D882), puncture resistance (ASTM F1306) and unrestricted thermal shrinkage (ASTM D2732). Other tests also report quality and characteristics, such as thickness and basis weight calculation.

[064] Initial tests show that the films produced have an intermediate density between the specific weights of r-PET and r-PA6, indicating good miscibility, as shown in Table 1. Table 1 - Results for determining the density, thickness, and basis weight parameters, both for the film used as Reference (100% PET) as for the 80% r-PET + 20% r-PA6 film. Parameters Films 100% r-PET 80% r-PET + 20% r-PA6 Density (g / cm3) 1.275 ± 0.035 1.322 ± 0.041 Thickness (cm) 0.014 ± 0.001 0.011 ± 0.001 Grammage (g / cm2) 0.018 ± 0.001 0.013 ± 0.001

[065] For the mixture 80% r-PET + 20% r-PA6, the compound in greater quantity (r-PET) has a density of 1.38 g / cm3 while the Petition 870260016621, dated 23 / 02 / 2026, pp. 63 / 79 The 23 / 26 compound in smaller quantity (r-PA6) has a density of 1.14 g / cm³. Theoretically, the density of the mixture should be close to the weighted average of the individual densities and their respective fractions (which, for this specific case, is 1.33 g / cm³). The density of the mixture reported in Table 1 (1.32 g / cm³) is very close to the theoretical value, demonstrating low loss due to degradation and little influence from contaminants, in addition to good dissolution of one polymer in the other (miscibility). Thickness tests showed films ranging between 50 and 70 μm, which is an excellent range for an anti-corrosion film (Table 1). Films below 20 μm are easily perforated, which is contraindicated for the intended purpose of the r-PET / r-PA6 films. The basis weight tests (material distribution per m2 of film) showed results close to 150 g / cm2, double, for example, that of an A4 sheet of paper (which has about 75 g / cm2), as shown in Table 1.This parameter is directly related to the thickness.

[066] Adhesives containing polyamide-6 and low-density polyethylene were characterized. For characterization, both transparent and opaque films were produced. The different adhesives (opaque and transparent) of each formulation were thermally characterized by TGA and DSC.

[067] From the TGA results (Figure 3), it can be observed that all pure films and blends presented similar thermal degradation ranges, around 400 - 450 °C. Although pure polyamide (PA6) showed slightly higher thermal resistance than pure PET, its presence in the blend ended up decreasing the degradation resistance of the whole, bringing it closer to 400 °C.

[068] Regarding the DSC results (Figure 4), more significant differences were obtained. In general, it can be seen that the opaque formulations presented less glass transition events and PET recrystallization peaks. Petition 870260016621, dated 23 / 02 / 2026, pp. 64 / 79 24 / 26 evident, indicating a higher degree of prior crystallinity compared to the transparent (and therefore more amorphous) samples. This can be explained by the lower cooling rate of the thicker regions of the film, generating a certain degree of crystallinity during processing (and greater opacity). The thinner regions, on the other hand, exhibit sufficiently high cooling rates to prevent partial crystallization of the material, ensuring greater transparency.

[069] In addition, electrochemical impedance spectroscopy tests, cyclic tests in climate action chambers, and exposure tests in a real atmosphere were performed. The electrochemical tests (Figure 5) demonstrated that the recycled PET adhesive produced by the extrusion route exhibits dielectric properties close to that of an intact coating, since the impedance modulus at low frequency in the presence of the adhesive is similar to the paint system, showing that the tested adhesive has insulating properties, preventing electrical conduction. The standardized coating used in the industry consists of layers of protective paints standardized by Petrobras N0013.

[070] Regarding atmospheric exposure tests and climate action chamber tests (Figure 6), the adhesive film showed excellent anti-corrosion properties, since at the end of the 25 complete cycles no corrosion products were detected in the defect region of the paint system, the region where the adhesive acted as a protective barrier (each cycle consists of 3 days under UV / condensation, followed by 3 days under salt spray and, finally, 1 day under low temperature, according to ISO 12944-9 / 18). The same behavior was observed in samples exposed to the natural atmosphere, following the ISO 2810:2020 standard, in a marine atmosphere, for 8 months (Figure 7). APPLICATIONS AND ADVANTAGES

[071] The films produced are applied to offshore and onshore structures, as well as in equipment maintenance and Petition 870260016621, dated 23 / 02 / 2026, pp. 65 / 79 25 / 26 metal structures with damaged paint, providing economic and productivity benefits by reducing operating and raw material acquisition costs and reducing the time required for application. Application is simple and achievable with minimal instruction, consisting of removing the coating that is not adhered to the substrate with a spatula, followed by cleaning the area with a damp cloth prior to applying the adhesive, which should be positioned at least 3 cm from the existing paint layer. If the area to be coated is larger than the area of ​​a single film, more than one adhesive can be used, provided that the edge is overlapped by another film with a minimum overlap of 3 cm. An illustrated application manual has been developed and accompanies the adhesive film.

[072] Furthermore, r-PET / r-PA6 adhesive films present economic relevance and productivity gains by potentially reducing operational and raw material acquisition costs, as well as decreasing the time required for their application. Because they are made from recycled materials, adhesive films also meet the demands of economic circularity by promoting the reduction, recycling and reuse of plastic polymers, aligning directly with social, environmental and governance (ESG) policies and the National Solid Waste Policy.

[073] In financial terms, the cost of the adhesive film is significantly lower than the cost of traditional repair (repainting). The necessary paint scheme (N-2680 + N-2677) for repainting (the area affected by corrosion) has an approximate commercial cost of R$ 900.00 per gallon (~3.8 L) and a yield of 2.6 m² / L (R$346.15 / m²). Conversely, 1 m² of r-PET / r-PA adhesive film (80%:20% m / m) costs approximately R$24.37. While a gallon of paint can protect 2.6 m² at a cost of R$900.00 (complete paint scheme), the same 2.6 m² protected with the adhesive film has an estimated cost of R$63.36. The costs Petition 870260016621, dated 23 / 02 / 2026, pp. 66 / 79 The 26 / 26 figures listed refer exclusively to raw materials and exclude costs related to personnel, training, electricity, and other expenses.

[074] It is very important to highlight that, while adhesive film has virtually instantaneous application and protective action, painting requires, according to standards N2680 and N2677, long intervals between applications, in addition to proper surface preparation. This not only requires rework, but also unavailability of the surface for maintenance, which can cause costly shutdowns in the operating plant. Furthermore, on offshore petrochemical platforms, the cost of personnel travel is high.

[075] From an environmental point of view, the use of recycled materials combined with a solvent-free manufacturing process guarantees concrete benefits both in the proper disposal of waste and in the adoption of a more environmentally friendly production process. This approach contributes to the reduction of environmental impacts and reinforces the commitment to sustainable practices throughout the entire production chain.

[076] In addition to economic and environmental advantages, the use of a durable adhesive system for preserving paint defects as an alternative to the usual repainting leads to significant savings in time, resources, and labor. In an alternative route to extrusion (casting), r-PET films were able to withstand weather conditions for about 2 years. Infrared spectroscopy tests confirmed the durability of the films. Due to the similarity between the film produced by the casting route and the films produced by the extrusion route, similar durability is expected. The extruded adhesive films are already undergoing durability evaluation in a relevant environment. Petition 870260016621, dated 23 / 02 / 2026, pp. 67 / 79

Claims

1 / 2 CLAIMS 1. Process for manufacturing anti-corrosion adhesive film characterized in that it comprises the following steps: (a) Preparation of raw materials, wherein the raw material is selected from the group consisting of recycled thermoplastic polymers, preferably poly(ethylene terephthalate) (rPET), polyamide-6 (r-PA6), r-LDPE (low-density polyethylene), r-HDPE (high-density polyethylene), r-PP (polypropylene); (b) Simultaneous feeding by separate feeders of r-PET and r-PA6, or r-PET and r-LDPE, or r-PET and r-HDPE, or r-PET and r-PP into the extrusion blocks; (c) Co-rotating extrusion; (d) Flat die thermoforming; (e) Controlled cooling; (f) Initial winding; (f) Unwinding and application of the adhesive layer; and (g) Final winding.

2. Process according to claim 1, characterized in that the r-PET and r-PA6 pellets are dried at 150 °C and 80 °C, respectively, for 24 h.

3. Process, according to claim 1, characterized in that the pellets fed into the extruder have a grain size between 1.80 and 2.50 g / 100 grains for r-PET, and between 1.00 and 1.20 g / 100 grains for r-PA6.

4. Process according to claim 1, characterized in that the extruder is equipped with two co-rotating helical screws, preferably 16 mm in diameter.

5. Process, according to claim 1, characterized in that the extrusion temperature occurs in a range between 200 °C and 250 °C, wherein the flat die represents the extrusion outlet where the homogenized liquid material is formatted into a film with a predefined thickness between 50 and 80 micrometers.

6. Process, according to claim 1, characterized in that during cooling, the film passes through a calender system with an internal cooling system consisting of distilled water with added anti-corrosive and anti-algae agents, being recirculated in a closed cycle by a chiller.

7. Process, according to claim 1, characterized in that the film is unrolled while receiving 50 μm of water-based acrylic glue on one of the film faces, followed by lamination with protective silicone paper (liner).

8. Process, according to any one of claims 1 to 7, characterized in that for every kilogram of feed, 920 grams of product are obtained.

9. Anti-corrosion adhesive film obtained by the process as defined in any one of claims 1 to 8, characterized in that it comprises a polymer blend of recycled poly(ethylene terephthalate) (r-PET) and recycled polyamide-6 (r-PA6), with proportions between 90 / 10 and 50 / 50, preferably 70 / 30, and an adhesive layer composed of water-based acrylic glue with a thickness of 50 μm, protected by a silicone liner.

10. Film, according to claim 9, characterized in that it has a thickness between 50 and 80 micrometers.

11. Use of the film as defined in claim 9 or 10, characterized by the fact that it is for application in the maintenance of equipment and metal structures with damaged paint, preferably in offshore and onshore metal structures. Petition 870260016621, dated 23 / 02 / 2026, pp. 69 / 79

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