Synthetic composite with engineered wood core coated with reinforced polymer and fibers for applications in civil construction.

Description

1 / 11 Synthetic composite with engineered wood core coated with reinforced polymer and fibers for applications in civil construction. FIELD OF APPLICATION

[001] This patent relates to a composite material intended for civil construction, designed for use in residential, commercial, and industrial buildings. The invention can be applied to walls, floors, roofs, and other structural or sealing elements, meeting the demands of dry construction, prefabricated systems in controlled environments (Off Site), and rapid assembly methods on the construction site. The composite combines the strength and stability of engineered wood, obtained in the form of glued laminated timber or cross-laminated timber, with the mechanical properties and protection of a fiber-reinforced polymer coating. In this way, the invention enables the reduction of environmental impact, improved thermoacoustic performance, and increased durability compared to conventional materials, contributing to sustainable construction practices. THEORETICAL FOUNDATION

[002] Currently, the construction industry relies on different technologies that seek to balance structural performance, sustainability, and speed of execution. Among these solutions are glued laminated timber (GLT) and cross-laminated timber (CLT), which exhibit good mechanical properties and contribute to reducing the use of high-impact environmental inputs, such as concrete and steel. Despite this, these engineered wood materials may be susceptible to moisture and fungi, requiring protective treatments, as well as more frequent maintenance in certain contexts.

[003] Meanwhile, concrete and steel, while robust, are responsible for high CO2 emissions and high energy consumption for their production, which increases the pressure for cleaner construction alternatives. In addition to these Petition 870250012804, dated 17 / 02 / 2025, page 5 / 23 2 / 11 options, systems like drywall and fiber cement panels are considered lightweight and practical, but they often offer lower structural strength and inferior thermal and acoustic insulation, which can become a limitation for certain construction types. Dry and Off-Site construction methods, which include the prefabrication of modules in factories, aim to reduce deadlines and waste, but still face challenges in obtaining panels or components that are simultaneously lightweight, durable, sustainable, and with appropriate thermal and acoustic insulation.

[004] Given this, there is a need for a material that can combine, in a single element, structural robustness, dimensional stability, protection against moisture and pests, thermoacoustic comfort and environmental sustainability, satisfying the demands for modernization and socio-environmental responsibility expected of the sector.

[005] Regarding the state of the art, we can cite the prior art BR112019024990A2, which comprises wood composites intended to increase mechanical strength and reduce degradation due to moisture and external agents. Although it mentions impregnation with resins and the use of structural techniques to extend the durability of the wood, it does not present the application of silane agents, which is a key element in the present invention. Furthermore, it does not detail the inclusion of multiple types of fibers (synthetic, natural, and hybrid) in the polymeric reinforcement, nor the specific application of MLC and CLT cores for Off-Site construction. The present invention differs by proposing a chemical adhesion system via silanes and by integrating a variety of fibers, ensuring greater structural versatility and better thermoacoustic performance.

[006] The prior art CN116061283B describes a method for laminating lignocellulosic materials with polymers to provide mechanical strength and structural stability. However, there is no explicit mention of the use of compatibilizers such as silane agents, nor of the strategic use of synthetic or natural fibers to modulate mechanical properties and Petition 870250012804, dated 17 / 02 / 2025, page 6 / 23 3 / 11 thermoacoustic. Patent D2 also does not show the use of MLC or CLT structures nor their application in Off Site construction. The current invention is distinguished by allowing the integration of a wide range of fibers and by ensuring reliable chemical adhesion through the use of silanes, optimizing durability and increasing resistance to external factors such as moisture and delamination.

[007] The prior art CN113492445B addresses the lamination and impregnation of wood with polymers to increase resistance to water, impacts, and other deterioration factors. Although it discusses the application of additives, it does not provide details on the combination of different fiber classes or the use of specific coupling agents, such as silanes. Furthermore, the patent does not identify the proposal of optimized MLC or CLT cores for modular construction. The present invention offers a differentiating factor by integrating mixed fibers (natural and synthetic) and applying silane-based coupling agents to improve adhesion between the wood and the polymer coating, resulting in greater dimensional stability and resistance to external factors in Off Site applications.

[008] Thus, the prior art found presents relevant points in the field of wood composites, but does not contemplate the synergistic combination of engineered wood, polymer coating reinforced by various fibers and silane coupling agents. The proposed invention stands out by providing an optimized solution for civil construction, combining superior mechanical strength, moisture protection, and constructive versatility, especially in Off Site methodologies, which ensures its inventive merit. SUMMARY OF THE INVENTION

[009] The present invention consists of a composite that utilizes an engineered wood core, manufactured in the form of glued laminated timber or cross-laminated timber, and a fiber-reinforced polymer coating in order to protect against moisture, fungi and insects, as well as to improve structural performance and thermal-acoustic insulation. Petition 870250012804, dated 02 / 17 / 2025, page 7 / 23 4 / 11

[010] The invention aims to overcome the limitations of traditional solutions by combining, in a single element, the advantages of renewable wood and a highly durable polymer matrix, promoting a longer lifespan and reduced maintenance needs. By adding coupling agents that reinforce the adhesion between the wood and the polymer layer, the invention overcomes problems such as delamination and susceptibility to damage from prolonged contact with moisture.

[011] In this way, the composite achieves excellent dimensional stability, greater load-bearing capacity, efficient heat retention and sound attenuation, as well as a lower environmental impact compared to options such as concrete and steel. Applications range from vertical and horizontal components to modular systems for Off-Site construction, prioritizing speed of assembly, reduction of on-site waste and more responsible use of natural resources. Thus, the invention offers a response to the growing demands for sustainable buildings, with simplified execution and better performance in terms of environmental comfort, while reducing maintenance costs and expanding the versatility of use of engineered wood in contemporary projects. BRIEF DESCRIPTION OF THE FIGURES

[012] The invention can be better understood through the following figures: • Figure 1: Presents the flowchart of the manufacturing process, including heat treatment of the wood, application of silanes, insertion of fibers, and curing of the system. DETAILED DESCRIPTION OF THE INVENTION

[013] The composite features an engineered wood core (MLC or CLT), obtained from dried veneers or boards with a moisture content preferably between 8% and 12%. Unlike usual processes that employ conventional adhesives (e.g., urea-formaldehyde or PUR), the present invention uses a special epoxy formulation based on bisphenol A diglycidyl ether resin (C21H24O4) and triethylenetetramine (CeHisN^, in the ratio Petition 870250012804, dated 17 / 02 / 2025, page 8 / 23 5 / 11 2:1, in order to obtain high cross-link density. The veneers are joined under curing conditions at 80 °C and 1.5 MPa, which ensures controlled penetration of the adhesive into the wood pores, forming a board capable of withstanding shear stresses above 12 MPa (ASTM D905). This 2:1 epoxy-amine procedure is not typical in engineered wood lamination, providing a synergy between stiffness, dimensional stability and superior chemical adhesion, which is not found in traditional processes.

[014] This engineered core (MLC or CLT) is distinguished by its dimensional stability, partly due to precise moisture control and the use of highly cross-linked epoxy adhesive. The initial step involves rigorous selection of the layers, verification of critical defects, and hygroscopic control, fundamental aspects to avoid long-term failures. After controlled curing of the adhesive, a cohesive block is obtained, ready to receive the protective coating, a step which, in this invention, is performed only after applying the silane treatment (described below). This sequence of steps (complete curing of the adhesive, post-treatment, and only then coating) differs from the usual and generates surprising interfacial adhesion properties.

[015] The proposed polymer coating includes a modified thermoplastic matrix (epoxy, polyester or polyurethane) to create a barrier against moisture and biological agents, as well as mechanically reinforcing tensile and flexural strength. This is not a simple coating: the inventor selects the resins according to the application (structural, acoustic, flexible, etc.), associating them with a silane treatment already established in the core. This procedure solves the chronic problem of delamination in coated wood applications.

[016] The thermoplastic matrix is ​​composed of: • Unsaturated polyester resin (synthesized from maleic anhydride and propylene glycol): C4H2O3 + CaHsOz ^ Unsaturated polyester (C10H10O4) + H2O • MEKP initiator (C4H10O2) generates free radicals at a controlled temperature (60 °C); Petition 870250012804, dated 17 / 02 / 2025, page 9 / 23 6 / 11 • Thermoplastic polyurethane (TPU): formed by the reaction of MDI (Ci5HioN2O2) with polyol (C2nH4n+2OD+1).

[017] The successive application of structural epoxy adhesive to the core, followed by silane treatment and, finally, polymer coating with fibers, allows combinations that are not found in conventional methods, as each layer is adapted to optimize adhesion and confer specific properties, something considered not obvious to a specialist accustomed to linear lamination processes.

[018] Fibers (glass fiber, aramid, jute, sisal or hybrids) increase the strength and durability of the coating. The invention provides for a range of 10% to 40% by volume of fibers, adjusted for each resin matrix, which makes it possible to customize stiffness and tensile strength. Unlike usual wood composites, where the fibers may only be superficial, here they can be applied by hand lamination, vacuum infusion or autoclave pressing onto the already functionalized wood block. • Glass fibers treated with γ-methacryloxypropyltrimethoxysilane (CioH2oO5Si): creates a functionalized surface layer on the inorganic fiber, ensuring bonding with the resins; • Jute fibers pre-treated in 5% NaOH: removes hemicellulose and makes the surface more reactive to the matrix.

[019] The simultaneous silane treatment in the core and the pre-treatment of the reinforcing fibers establishes double compatibility, avoiding interfacial failures — an approach that is not widely used in hybrid wood and natural / synthetic fiber systems.

[020] To create strong chemical bonds between the lignocellulosic surface and the polymer matrix, a silane agent is applied only after lamination and curing of the core. This step goes against conventional processes (where silane can be included directly in the glue or applied before gluing), and solves instability problems in handling raw wood: Petition 870250012804, dated 17 / 02 / 2025, page 10 / 23 7 / 11 • 3-aminopropyltrimethoxysilane (APTES, CeH^NOsSi) is hydrolyzed in an acidic medium (pH 4-5): CeHnNOaSi + H2O ^ C6Hi7NO3Si(OH)3 (silanol) • Next, a reaction occurs with -OH groups of lignocellulose: Si(OH)3 + Cellulose-OH ^ Si-O-Cellulose + H2O • And finally, the silane also binds to the future polymeric matrix (epoxy, polyester or PU).

[021] Application by immersion (5% v / v in ethanol) and subsequent drying at 60 °C forms covalent bonds that do not break easily. This method of treating the already shaped piece of wood increases resistance to delamination (ASTM D1876 > 4 MPa) beyond the usual standard, demonstrating a non-obvious advantage compared to common primers.

[022] Summary of the manufacturing process: 1. Core lamination: Wood veneers are impregnated with epoxy resin (C21H24O4) in a 2:1 stoichiometry of hardener and pressed at 80 °C and 1.5 MPa. This curing cycle provides high internal cohesion to the core. 2. Silane functionalization: APTES (CeHi7NO3Si) is sprayed only after the core has cured, ensuring direct molecular adhesion to the cross-linked wood. 3. Coating application: Using vacuum infusion (or another method), epoxy resin (or polyester / polyurethane) with glass fibers (or natural fibers) is injected in a volume of up to 60%. This transition from already functionalized wood to fiber lamination without compromising the interface is the differentiating factor. 4. Final thermal curing: Treatment at 120 °C for 1 hour (in the case of epoxy) to achieve a conversion degree above 95%. 5. Final machining: Cutting and fitting for assembly and placement of accessories (±0.5 mm, ISO 2768). Petition 870250012804, dated 17 / 02 / 2025, page 11 / 23 8 / 11

[023] The novelty lies in the way the initial epoxy adhesive, subsequent silanization and subsequent fiber lamination are combined, all converging to a chemically active and homogeneous surface.

[024] Differentiated technical properties: • Rule of mixtures (traction): σε= να·σα + Vf·σf Va=0.6 σ□=30MPa Vf=0.4 σf=3000 MPa

[025] Where: • σc: Tensile strength of the composite (the value to be determined). • σα: Tensile strength of the matrix (polymer or “continuous phase”). • af: Tensile strength of reinforcing fibers (e.g., fiberglass or natural fiber). • Va: Volume fraction of the matrix (i.e., what percentage by volume of the composite corresponds to the matrix). • Vf: Fiber volume fraction (what percentage by volume of the composite corresponds to fibers).

[026] We get: σε=1242MPaα

[027] This value is high for wood-fiber hybrid panels and is due to the post-curing silane treatment, which is unprecedented on a large scale. In addition, water absorption <5% (24 h, ASTM D570) is much lower than conventional wood panels, which can exceed 10% to 15%. This barrier results from the silane-cellulose interface and the polymer coating. Petition 870250012804, dated 17 / 02 / 2025, page 12 / 23 8 / 11

[028] The benefits of the end result are: Petition 870250012804, dated 17 / 02 / 2025, page 13 / 23 9 / 11 1. High mechanical performance in compression, tension, and bending; 2. Reduced moisture absorption and consequent inhibition of fungi or wood-boring insects; 3. Excellent thermal and acoustic insulation, superior to common lightweight systems; 4. Lower weight compared to concrete or steel structures, ideal for off-site applications.

[029] The combination of these benefits is, in part, not obvious, as it combines processes and materials in a sequential manner (laminated wood, epoxy adhesive curing, silane post-treatment, fiber-infused polymer coating). Furthermore, the use of reforestation wood contributes to a more sustainable civil construction, with a smaller CO2 footprint.

[030] In addition, the following are inventive application methods: • CLT / epoxy-fiberglass structural panel: CLT core (7 layers) + epoxy coating (40% vol. glass fibers). The curing reaction (epoxy + TETA) occurs with optimized parameters, resulting in Off-Site columns with axial loads > 1000 kN (EN 1995-1-1), replacing steel beams with a 40% weight reduction. The application of silane post-lamination provides an unusual fiber-matrix adhesion, indicating a structural gain unattainable by standard methods. • Polyurethane-jute acoustic panel: MLC core + TPU coating (e.g., MDI derivative + polyols) with 30% jute by volume. This is a lightweight solution (focused on thermal and acoustic comfort) that achieves a noise reduction of 45 dB (ISO 10140-2) and VOC < 50 μg / m3 (ISO 16000-6), thanks to the well-adhered polymer barrier via silanization. • Thermoacoustic floating floor (polyester-sisal): Core: CLT + unsaturated polyester (C10H10O4) + sisal fibers. Polymerization occurs through the action of MEKP, generating a rigid network with impact absorption of 15 kJ / m2 (EN 12667) and resistance to fungi. Petition 870250012804, dated 17 / 02 / 2025, page 14 / 23 10 / 11 (ASTM G21). The synergy between engineered wood and resin infused in natural fibers is maximized by the prior silane functionalization of the core, inhibiting delamination.

[031] Other specific applications are listed, demonstrating its competitive advantage: 1. High-strength pillars and partitions (fiberglass / epoxy): They support high loads and withstand bending stresses of 250 MPa (EN 408). This bending strength value is higher than that of fiber cement panels (80-120 MPa), demonstrating a significant performance improvement. 2. Lightweight modular systems (polyurethane / jute): Allowing for adjustable internal partitions and "floating floors" in the range of 15kg / m2, achieving a modulus of elasticity of 1.2 GPa. The combination of wood and natural fibers, already silanized, explains the good acoustic insulation (Rw 45 dB). 3. Elements for high humidity environments (mixed fibers): Exterior facades, roofs, and areas such as bathrooms or kitchens receive a polymeric coating (combining synthetic and natural fibers) which, together with silane, reduces water absorption to <2% (ASTM D570) and withstands thermal cycles (-20 °C to 60 °C, EN 13687). The non-obvious aspect here stems from the ability to integrate mixed fibers into the same matrix without loss of adhesion at the interface with the pre-treated wood.

[032] Final result of the composite: 1. An unusual epoxy-amine (2:1) formulation for laminating wood under specific temperature and pressure conditions, generating a highly cohesive core; 2. Post-lamination silane treatment, which enables superior chemical adhesion between the lignocellulosic core and the future polymer coating; 3. Infusion of fibers (natural, synthetic or hybrid) into epoxy, polyester or PU resins, with optimized volume fractions (10% to 60%); Petition 870250012804, dated 17 / 02 / 2025, page 15 / 23 10 / 11 4. Set of properties (low water absorption, high resistance to Petition 870250012804, dated 17 / 02 / 2025, page 16 / 23 11 / 11 delamination, high rigidity and acoustic performance).

[033] The synergy that arises from the sequence (epoxy lamination ^ curing ^ silane treatment ^ reinforced coating) is not obvious to specialists, as silane is usually applied before or during bonding, or typical CLT adhesives (melamine, resorcinol, PUR) are used. The mechanical robustness, impermeability and biological resistance obtained surpass known solutions, indicating novelty and inventive activity for use in Off Site construction systems, acoustic panels and high-performance partitions. Petition 870250012804, dated 02 / 17 / 2025, page 17 / 23

Claims

1 / 2 CLAIMS 1) SYNTHETIC COMPOSITE, characterized by comprising an engineered wood core obtained by laminating dry veneers with a moisture content of 8% to 12%, joined together in a board, by an epoxy formulation in a 2:1 ratio between Diglycidyl ether of bisphenol A (C21H24O4) and Triethylenetetramine (C6HisN4) resin, subjected to curing at a temperature of 80°C and a pressure of 1.5 MPa, receiving, after curing, a silane agent applied directly to the core and, finally, a fiber-reinforced polymer coating, selected from epoxy, unsaturated polyester or thermoplastic polyurethane resins, with a fiber volume content between 10% and 60%; 2) SYNTHETIC COMPOSITE, according to claim 1, characterized by the application of the silane agent only after the completion of the epoxy adhesive curing stage, in order to allow the formation of chemical bonds between hydroxyl groups of the lignocellulosic surface and the subsequent polymeric coating; 3) SYNTHETIC COMPOSITE, according to claim 1, characterized by the use of 3-aminopropyltrimethoxysilane (APTES) in solution, previously hydrolyzed at a controlled pH, to promote chemical compatibility between the wood core and the polymeric coating; 4) SYNTHETIC COMPOSITE, according to claim 1, characterized by incorporating synthetic or natural fibers, selected from fiberglass, aramid, jute, sisal or combinations thereof, applied by hand lamination, vacuum infusion or autoclave pressing; 5) SYNTHETIC COMPOSITE, according to claim 1, characterized by the integration of synthetic and natural fibers in a mixed form in the polymeric coating, together with the post-cure silane treatment of the core, enabling combined layers that optimize interfacial adhesion; Petition 870250012804, dated 02 / 17 / 2025, page 18 / 23 2 / 2 6) SYNTHETIC COMPOSITE, according to claim 1, characterized by the adoption of a staged curing process, comprising initial curing of the epoxy adhesive at 80°C in the core and subsequent post-curing of the polymeric coating at temperatures up to 120°C, intensifying the crosslinking and the fiber-matrix interface; 7) METHOD, according to claim 1, characterized by the steps of (i) drying and selecting wood veneers to a moisture content between 8% and 12%, (ii) bonding the veneers with the epoxy formulation in a 2:1 ratio under a temperature of 80°C and a pressure of 1.5 MPa, (iii) complete curing of the epoxy adhesive, (iv) application of the silane agent to the cured core, (v) deposition of a fiber-reinforced polymer coating, and (vi) curing of the coating under temperature conditions suitable for the resin used; 8) METHOD, according to claim 1, characterized by the use of 3-aminopropyltrimethoxysilane (APTES) in hydroalcoholic solution, applied to the wood core by immersion or spraying, followed by drying at a temperature of up to 60°C, allowing subsequent chemical adhesion of the polymeric coating; 9) METHOD, according to claim 1, characterized by the step of depositing the reinforced polymeric coating including vacuum infusion with epoxy resin, unsaturated polyester or thermoplastic polyurethane, followed by thermal curing to form cross-links in the matrix. Petition 870250012804, dated 17 / 02 / 2025, p. 19 / 23

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