The world of hot melt is a multifaceted one. As scientific breakthroughs continue to occur around the world, new products are developed to better serve an ever-expanding variety of industries, markets, and commercial applications.
“Hot melt” itself is a phrase used to describe thermoplastic or thermoset materials that are heated to a liquid state so they can be applied to and bond substrates. When cooled, they typically cure in a solid state.
Hot melts are used as adhesives on things you come into contact with on a daily basis, including cabinetry and furniture, food packaging, countertops, major appliances, shoes, mattresses, and a lot more! The most well-known, high-performance types of hot melt are ethyl vinyl acetate (EVA), polyolefin, polyamide, and reactive urethanes.
We’ll be exploring a unique member of the reactive urethane family, Henkel TECHNOMELT polyurethane reactive (PUR) adhesive, in this definitive guide.
What Makes Henkel TECHNOMELT Polyurethane Hot Melts Better?
At Hotmelt.com, we cherish the opportunity to work with providers that love what they do and care about their customers, partners, and planet. Henkel is one of those awesome providers. On our blog, we’ve covered everything from choosing between its wide assortment of hot melt adhesives to tips on achieving great results with its TECHNOMELT line of hot melt adhesives.
Since Henkel opened its doors over a century ago, the company has provided nothing but the best in customer service and innovation. One factor that truly sets it apart from its competitors in the adhesive and sealant industry is how it promotes sustainability and social responsibility.
Throughout this definitive guide, we’ll cover everything you need to know about Henkel TECHNOMELT PUR, including the brand’s focus on reducing waste and the use of VOCs, formaldehyde, and other dangerous chemicals that cause health and environmental concerns.
How Do Henkel TECHNOMELT Polyurethane Hot Melts Work?
Introduced in the 1990s, PUR adhesives have a hybrid chemistry designed for elevated temps, high flexibility, and all-around high-impact situations.
The advantages of traditional thermoplastic technology combined with the performance characteristics in other reactive adhesive chemistries make Henkel TECHNOMELT PUR uniquely suited for a wide variety of applications and industries.
PUR is what’s known as a “single system.” It combines the production benefits of hot melt adhesives with the bonding performance of two-part structural adhesives. As it cools and cures, PUR reacts with moisture in the air to crosslink. This forms a new polyurethane polymer that provides strength and flexibility which is unheard of in traditional hot melt varieties. And, because it is a single system, PUR is easy to dispense, with no additional metering, mixing, or curing needed.
How Should I Apply Henkel TECHNOMELT Polyurethane Hot Melts?
Henkel TECHNOMELT PUR adhesive can be applied at temps ranging from 85°C to 140°C (185°F to 284°F), which is cooler than many other hot melt varieties.
Thermally sensitive substrates are great candidates for PUR due to their low-temp application compared to traditional hot melts, which can reach temps ranging from 190°C to 230°C (375° to 450°F).
PUR can be engineered from 2,000 cPs (centipoise units—a measure of viscosity) all the way up to 60,000 cPs. At a higher viscosity, reactive urethanes will set quickly and become structurally rigid in just minutes. This makes them great for line manufacturing processes that can’t afford to be interrupted. Meanwhile, that secondary moisture cure we mentioned earlier will continue for up to 24 hours.
Because it bonds as it cools, PUR naturally has a low green strength. However, it can also be formulated to have an open time ranging from just seconds to 10 minutes, allowing for a variety of application methods and unique production requirements.
Where Can I Use Henkel TECHNOMELT Polyurethane Hot Melts?
Henkel TECHNOMELT PUR has been carefully engineered to support even the most demanding of projects. Because of the flexibility of its application temperature and viscosity, as well as being a single-system adhesive, you’ll find PUR used in everything from food packaging to key pieces of your major kitchen appliances.
Adhesives today must have a long shelf life while still being able to cure quickly when dispensed. Because of its two-fold reaction with heat release, and then with moisture in the air and substrates, PUR remains solid and shelf-stable right up until the time it’s used—making it a great adhesive for modern enterprise. The flexible yet tough finish PUR leaves behind makes nearly invisible bondlines, which improves the overall fit and aesthetic of bonded products.
Here are some of the industries that are making the most of Henkel TECHNOMELT PUR’s benefits:
Woodworking
Carpenters, contractors, DIY woodworkers, and furniture manufacturers find Henkel TECHNOMELT PUR affordable, efficient, and versatile. PUR can be used as the primary bond for soft- and post-forming, profile wrapping, and other architectural or aesthetic applications. It can also provide a quick fix when installing hardware fasteners, waiting for wood glue to cure, or quickly tacking on hardware fixtures so you can step back and make sure everything is lined up perfectly.
Cabinetry and Furniture Making
Assembling cabinets, drawers, and other furniture pieces is a resource-draining and time-consuming process. While hot melt has been used for years to affix panels, Henkel TECHNOMELT PUR can make finishing cabinetry and furniture faster and better looking. Use PUR to provide superior strength and precision, as well as save a lot of time and money on labor, hammers, and nails.
Construction
When it comes to construction and remodeling, you name it, and we bet Henkel TECHNOMELT PUR can handle it. We’ve seen it used on window seals, gaskets, foam, fabric, plastic, particle board, light metal applications, and more!
PUR is also great for securing solid surface installations while silicone sealants set. Because of its flexibility and resilience in wet and warm environments, Henkel Technomelt PUR is one of the few adhesives that holds up in damp areas like countertops, showers and tubs, and basements.
Henkel TECHNOMELT PUR also ensures a solid bond and can be used to achieve excellent hard seams in vertical applications like wall cladding, wainscoting, baseboards, and molding.
Product Assembly
Product assembly accounts for a huge variety of applications. Luckily, Henkel TECHNOMELT PUR can rise to meet almost any occasion. Henkel TECHNOMELT PUR will bond with nearly any substrate, including glass, plastic, metal, paper, and other materials commonly used in manufacturing.
It can be engineered to have an open time of just seconds, in the case of fast-moving automated assembly lines. Because it’s a single system product, there is no additional drying time, mixing, or measuring. Because it holds up better than most adhesives under wet or harsh environmental conditions, PUR makes for a great adhesive on almost any assembly line.
How Strong Are Henkel TECHNOMELT Polyurethane Hot Melts?
Henkel TECHNOMELT PUR adhesive is highly resistant to solvents and chemicals, is flexible, and is compatible with a range of substrates. Its impressive strength has great implications for applications that require fail-safe bonds.
PUR has proven to be significantly stronger than traditional hot melt adhesives. Its unique secondary moisture bond gives it up to a half ton of holding power just 10 minutes after application. In fact, a 3M edge splice test found that a substrate would give way well before a bond created by a PUR adhesive.
How Do Henkel TECHNOMELT Polyurethane Hot Melts Stand Up to Heat?
One of the factors that gives Henkel TECHNOMELT PUR a competitive advantage over other hot melt adhesives is its resistance to harsh environmental elements. PUR can maintain a strong bond even in extreme temperatures ranging from -40°C to over 95°C (-40°F to 200°F). It is uniquely suited for heat-sensitive products; bonding appliance housings and cabinets; bonding thermal and sound insulation panels in dishwashers and dryers; and adhering labels, nameplates, touchpads, and vinyl gaskets.
How Do Henkel TECHNOMELT Polyurethane Hot Melts Address Health and Environmental Concerns?
Henkel TECHNOMELT PUR has a leg up when it comes to environmental concerns that are commonly linked to adhesives. Since it is 100 percent a solid, PUR has no volatile organic compounds (VOCs), and no drying ovens are required in its curing process. Not only does this eliminate environmental concerns associated with solvent-based adhesives but also with the energy expenditure required to dry water- and solvent-based adhesives. The adhesive contains no formaldehyde or solvents. Its solid state also means it doesn’t produce any nasty or harmful odors in the work environment.
In addition, PUR is such a powerful and versatile adhesive that many industries are able to improve their efficiency, generate less waste, and use a whole lot less temporary and permanent fastening material like tape, nails, dangerous chemical glues, etc. That may not sound like a big deal, but, for builders who do thousands of houses in a year or for an assembly line that sees millions of products passing through, even the little things add up!
The Future Is Here
We feel secure in our opinion that Henkel TECHNOMELT PUR is one of the best things to happen to hot melts and the industries that use them in a long time. PUR combines the best of both adhesive worlds: the production benefits of hot melt adhesives and the bonding performance of two-part structural adhesives. Its single system delivery makes application fast, easy, and environmentally friendly, without sacrificing any of its extraordinarily strong holding power.
PUR’s flexible viscosity and application temperature paired with its imperviousness to extreme heat, cold, and wetness mean it can be used in practically any situation you can think of. For woodworkers, cabinet and furniture makers, construction professionals, and manufacturing and assembly workers—what’s not to love?
The future of adhesives is here. It’s Henkel TECHNOMELT PUR.