ADHESIVES IN THE WOODEN FURNITURE SECTOR, AN ESSENTIAL ADDITION
Concentrol, the leading chemical solutions company, is organized into four divisions, from which it works to respond to specific day-to-day needs of the industrial sector. One of the company’s divisions is Adhesives, at which product lines are made tailored to the needs of each client thanks to the transversal knowledge that the professionals who work there have.
One of the sectors that is addressed at the adhesives division is solutions designed for the furniture market, a very broad sector that the company has divided into two subsectors: office furniture and wooden furniture.
The application of adhesives on wooden furniture
The wooden furniture sector is a very interesting market segment, and is mainly made up of manufacturers who make edge banding or lining moldings.
Much of the interior and exterior furniture of homes is joined together thanks to the technology of adhesives, which can be hot-melt or water-based and can be applied in two different ways:
Edge Banding
Edge banding is very common when bonding wooden board surfaces and requires a careful technique when applying the hot melt polyurethane adhesive and applying pressure to the rollers. There are factors that can influence this application such as the moisture in the wood, the ambient temperature or that of the work piece.
Adding edge bands to furniture is a very important aspect for the end customer, which requires well-placed adhesive joints that are aesthetically pleasing and not very visible. In addition, with the use of hot-melt polyurethane adhesives, these edge bands also offer high stability and strength properties for the final parts.
After years of working in this sector, we can be sure that great progress has been made in terms of innovations in this sector. Today’s technology, which has made a significant leap forward thanks to the incorporation of laser technology, is able to respond to the current increase in edge adhesion requirements for all types of furniture.
Edge banding is another common practice in the furniture industry. What is sought with this process is an aesthetic and visually clean finish, which makes the final piece of furniture a higher quality product. Highly charged EVA-based hot melts were originally used for this task, then non-charged or lightly charged EVA-based products, and nowadays it is common to use HMPUR technology. In our case, we will focus on the edge banding of chipboard veneered with Formica and melamine, PVC edge bands.
Profile Wrapping
Profile wrapping forms a very important emerging market in the framework of the wood and furniture industry.
Ranges of hot melt products based on PUR, PO and EVA are used for its construction. What is sought are solutions that do not lead to the formation of strings, are easy to clean, and offer airtight joints.
The materials used for the coatings can be varied, as can the areas of application: kitchen furniture, doors, interiors or caravans, for example.
Wrapped molding is one of the most important elements in the furniture and interior construction industry. Various materials are used to wrap moldings depending on the finish required, so the adhesives used must be versatile, high temperature resistant, fast gluing and visually appealing.
Polyurethane hot melt adhesives are used whenever there are high demands on the quality of adhesion and the need for resistance to moisture and heat. These adhesives are developed to meet all the requirements in the coating of profiles and moldings, coating of drawers or decorative panels of natural wood veneer or sheet of paper, PVC, PP or high pressure laminates. In our case, we will focus on curved or flat moldings coated with materials as diverse as varnishable paper or not, wood veneer or PVC.
Surface lamination
Polyurethane hot melt adhesives for surface lamination represent another booming market line in the wood and furniture industry, in particular in wood panels, veneers, continuous pressure lamination (CPL) and high pressure lamination (HPL).
Depending on the substrates to be joined, different technologies and adhesives can be applied (HMPUR, non-reactive HM and / or water-based adhesives).
The application areas are varied, from kitchen and home furniture to doors and floors.
Polyurethane hot melt adhesives are well established in the market and are required whenever there are high adhesion requirements.
These adhesives stand out in glossy material-based sheets and are characterized by low processing temperatures, excellent strength and extraordinary adhesion, and low VOC emissions.
In order to obtain an optimal result, a flat, resistant and attractive surface is sought, and to achieve this, the best allies are hot melt adhesives.
We can also find adhesives for applications such as:
Many applications are used for the assembly of wood, such as gluing edges, inserting bolts, joints or notching, among others. HMPUR, non-reactive HM, single or bi-component PU or vinyl D1 to D4 adhesives are used for the assembly of wood parts.
3D thermoforming is an innovative adhesive application used in the manufacture of high quality kitchen unit frontal panels, for example.
Edge sealing is an important application in the construction and furniture sector that offers protection against moisture and steam for kitchen worktops, as well as stabilizing cutting edges and the ability to seal narrow surfaces. HMPUR, non-reactive HM adhesives or UV curing products are used.
The lamination of sandwich panels covers the functions of structural construction and insulation in spaces such as door and roof panels, and decorative and insulation panels. Different varieties of PUR-based adhesives are used due to their great versatility.
Foam adhesive bonding is a major application for the production of mattresses or lid furniture and bagged molds.
The manufacture of the parts
We will focus on the polishing process and on the profile wrapping or flat molding wrapping.
Edge Banding
Edge Banding is the name given to a process as well as an associated narrow strip of material used to create molding edges that are durable and aesthetic.
Edge bands are used to cover exposed sides of materials such as plywood, particleboard or MDF, increasing durability and giving the appearance of a more solid and valuable material. They can be made of different materials, although the most common is PVC.
In modern, large-scale manufacturing processes, the edge bands are applied to the substrate by an automated process in which a Hot melt is used. Hot melt adhesives can be based on EVA, PUR, PA, APOA and PO.
The thicker edge bands, which are usually slightly concave, are attached to the substrate by a machine called an edge gluer. What this machine does is cut the front and back ends, cut the top and bottom along the substrate, remove the excess and polish the finished edge band.
A Thermoplastic Edge Band is produced with an extruder, a machine that extrudes the edge band so that it can be textured, printed and lacquered later.
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The process of covering the rough corners of wooden panels with a thin strip of wood, PVC, or resinous material is called edge banding, and narrow strips are known as edge bands. They are joined by industrial grade heat applicators and a hot melt adhesive.
Modular furniture is made of synthetic wood that is treated to make it resistant to moisture. However, wood has a natural tendency to absorb water. In this sense, the edge bands protect the wood panels from moisture, increasing their strength and durability.
The edge bands of modular furniture can be made of acrylic, wood or wood veneer, although PVC is the most common because of its impermeability. In addition, PVC is easier to use on curved surfaces and incorporates the option to create PVC strips that match the exact hue and finish of the modular panel, creating a perfect look.
An edge band is a thin strip of waterproof PVC that is cut to fit the size of a wooden panel. This is applied to the raw end with a strong adhesive, an EVA-based Hot melt or an HMPUR adhesive. Then, in the case of the EVA or PO-based Hot melt, a heat roller is used to melt the adhesive and glue the end band to the wood, while in the case of the HMPUR follower plates are used. The ends are then cut and bent so that they cover the wood and have no sharp ends. Finally, the excess glue is scraped off, and the piece is polished to have a flawless result.
Molding wrapping
The advancement of technology has led to the creation of profile coating or wrapping machines, specifically designed for this task. In these processes, some aspects need to be taken into account, such as the types of finishes, the humidity and ambient heat, the types of substrates to be joined, the post-treatment of the finished product, the size of the molding and the final destination.
The industries where this technology can be used are: Industries that process products derived or composed of wood, or the furniture, plastic or metalworking industries.
The substrates that can be laminated vary greatly, ranging from wood (particle board, medium density fiberboard, high density, plywood and extruded wood), solid wood, plastic (PVC, PP, ABS, extended polystyrene, etc.) or metals (aluminum, steel, etc.).
Regarding the materials used to wrap and superimpose, we can highlight:
The most commonly used adhesives for this application are hot melt adhesives:
Hot melt is the most widely used adhesive in the profile wrapping industry. The main advantages of this product are the high potential for combination of materials, the speed of drying, the elasticity and cohesion, the absence of solvents and the highest possible transport speed of the profile-wrapping machine.
The main difference between conventional adhesives and reactive adhesives is the reactivity of the latter against moisture, which confers an irreversible chemical bond when its final curing state is reached and makes the product remain thermostable. Once this entanglement is finished, it is impossible to reactivate and liquefy again, as it is completely cured. As a result, moisture-reactive adhesive compounds are resistant to water, other solvents, and extreme temperatures.
Non-moisture reactive adhesives are:
Moisture-reactive adhesives are:
Below you can find possible combinations and recommended products.
The Concentrol range
NETMELT
Hot melt adhesives, also called hot glues, are solid thermoplastics at room temperature, plastics at higher temperatures, and liquids at application temperature. Once melted, hot-melt adhesives adhere to the materials and, when cooled, a high-cohesive, resistant and highly elastic bond is obtained.
The main advantages of using hot melt adhesives are the absence of solvents, the instant adhesion to other materials, their easy application, their flexibility, their ability to fill gaps and their good stability during storage. However, their limitations are: they need good temperature control, are sensitive to some solvents and chemical agents, have a short open time and have limited adhesion under shear stresses at high temperatures.
The great versatility of Concentrol’s NETMELT range means that these applications can be applied to multiple sectors such as food, furniture, graphic arts, packaging, electronics, wood, textiles and automotive, among others.
Product lines
Concentrol manufactures hot melt adhesives based on different polymers, such as EVA (NETMELT PC), Polyolefin or APAO (NETMELT PLUS), synthetic rubbers (NETMELT TACK) or reactive polyurethanes (NETMELT PUR). The product lines are:
EVA base:
Polyurethane:
TACKTROL
The TACKTROL product range consists of water-dispersive adhesives. Their composition can be defined as modified aqueous organic polymers.
Among the features of Concentrol products are some such as: they are ready to use, are cold-applied, their versatility to adapt to each application, adjustable open times, are easy to wash with water, they have easy adhesion on large number of supports, high final strength, good forging speed, waterproofing and heat resistance are adjustable, and they are VOC free.
Product lines
Concentrol’s product lines focus on joinery assembly processes, and are as follows: