Definition
Adhesives, also known as Polymer Resins (polyesters, vinyl esters, modified acrylics, epoxy resins, phenolic resins and polyurethanes based), can bond reinforcing fibers together in an orderly manner. In composite materials, fibers and fabrics play a reinforcing role, while resins are the matrix material. Polyurethane composite construction materials are showing more advantageous characteristics in construction applications.
Overall summary
Whether it is a new construction project or a renovation project, the advantages of polyurethane composite building materials made of polyurethane adhesive are gradually being explored, including durability, light weight, corrosion resistance, high strength and low maintenance. Composite products have high flexibility in product application due to their good designability. Technically we call them fiber reinforced plastics/polymers (FRP), and they usually consist of two raw materials: reinforcing fibers and polymer binders (usually called matrices). Factors such as product size, shape, weight/volume ratio, and reinforcing fiber materials usually determine the mechanical properties of plastic composites, such as stiffness and strength. The type and addition ratio of the polyurethane resin matrix give the finished product different physical properties, such as impact resistance.
Advantages in natural fiber composite applications
PU composite building materials are usually produced by compression molding with polyurethane adhesives. The structural properties of plastic composites depend mainly on the type of fiber used. Although glass fiber is the main component of many plastic composites, it is now also available with carbon fiber, aramid fiber or boron fiber. These raw materials provide stiffness and strength to composite materials, which can meet various application areas. In the past 10 years, plant fibers and wood fibers have also been widely used, especially in residential construction. Although polyethylene, polyvinyl chloride (PVC) and polypropylene are the main polymer resins used in natural fiber composites, natural fibers can also be used in composites with phenolic resins, polyesters, polystyrene, polyurethanes and other polymer matrices.
Many current polyurethane composite building materials, the addition of natural fibers, mainly from the epidermis of plants (such as wheat straw fibers, flax, jute, kenaf, sisal, hemp, and coconut), are bonded with PU adhesives such as polyester or polypropylene. Due to the moderate mechanical properties of natural fibers, they are usually not used in high-performance applications, but the fibers themselves are lightweight and have good strength and stiffness and excellent bending stiffness. Another natural fiber, wood, is mainly used in composite panels for building products such as decks, door and window profiles, decorative trim, railings and panel products. These PU composite construction materials usually contain 30% to 70% wood fiber depending on the application area, with 50% being the most typical application. Regardless of the ratio, the reinforcement used in wood-plastic composites is usually wood chips or wood particles, which are molded and compounded with a polyurethane adhesive.
Advantages in specialty composite applications with high wood content
Common fiber varieties are mainly derived from pine, maple and oak. Some manufacturers use PU thermosetting resin adhesives to produce specialty composites with higher wood content. For inorganic fiber composites, small amounts of other materials can be added to wood plastic composites (WPCs) to improve processing efficiency and performance. Additives may include coupling agents, light stabilizers, pigments, lubricants, fungicides and foaming agents. Polyurethane adhesives are mainly used in the construction industry for floors, walls and roofs. Composites can also simulate bricks or stones for building exterior wall decoration. Inside buildings, composites can be used in shower enclosures, bathtubs, sinks.
Advantages in composite sheet applications
Polyurethane adhesives can be used to make a variety of composite panels of different specifications, including particleboard (OSB), hardboard (HB), medium density fiberboard (MDF) and cardboard, particleboard (PB), and plywood (LVL). It is usually used as structural protection, flooring and roofing of residential buildings. Wood plastic composites are often used as outdoor flooring, door frames, fences and other applications that require durability. If the correct manufacturing and installation procedures are adopted, wood plastic composite products rarely rot, crack, or warp under most normal climate conditions in the United States. In addition, this kind of board is resistant to stains, water, UV, not susceptible to insect infestation, and has good load-bearing capacity. They also tend to have good dimensional stability and a lower coefficient of expansion than hard plastics, which is better than the dimensional stability of wood. Wood fiber, wood chips, rice husks and other commonly used organic fillers in these applications.
Advantages of application in scenes such as doors and windows
Doors and windows are the most typical applications. Polyvinyl chloride (PVC) is often used as a thermoplastic resin matrix in the field of doors and windows (although other plastics also use this raw material). The fibers used in this field are usually 80 to 200 grid wood fibers, which produces wood-filled polyvinyl chloride (PVC) products with good stability, moisture resistance and stiffness. In new exterior applications, vinyl and polyolefin (such as polyethylene and polypropylene) plastic resins, wood chips mixed with a certain proportion of PU adhesives to make wood-plastic composites have good corrosion resistance and weather resistance.
Advantages of using in sandwich panels
Another commonly used sandwich structure is made of lightweight sandwich materials and composite materials laminated with polyurethane adhesives. Doors are mainly made of fiberglass reinforced plastic (FRP) surfaces and polyurethane foam or expanded polystyrene (EPS) sandwiches. Currently, this type of product is mainly used in residential and commercial projects. These composite "sandwich" sandwich doors provide high specific strength and specific stiffness, light weight, good impact resistance, and uniform and smooth surface texture. Other considerations, such as sound insulation, heat resistance, and vibration damping, determine the choice of core material.
Conclusion
In short, the various materials complement each other in terms of performance, producing a synergistic effect, so that the comprehensive performance of composite building materials made of polyurethane adhesives is better than the original component materials and meets various requirements. Fillers or additives can also make the finished composite materials resistant to ultraviolet (UV) light or fire. Leading composite material production technology provides people with more application opportunities and can customize high-performance composite materials for various commercial and residential buildings.
