Now over 50 years ago, hot melt adhesives revolutionized the packaging industry. These special adhesives are thermoplastic compounds or polymers that are solid at room temperature and liquefy upon heating, and re-solidify with cooling to create a bond. Hot melts save energy because they require less energy to melt than water or solvent based adhesive require to dry or cure. They also save you on costly solvent extraction equipment, associated with solvent based adhesive. With the elimination of drying ovens or clamping areas, they save plant space too.
Previously, packaging companies were using case erectors and sealers in their processes. With the introduction of the new technology, these companies easily switched to it because it allowed rapid sealing and closure of containers.
Basically, these adhesives are low-temperature plastics that form quickly with the loss of temperature. They bond efficiently to paper-based substrates used in corrugated packaging. When they were first introduced, they were a time and cost-savings… now, because of the ranges of prices, sizes, open times, set times, softening points and viscosities, there are more opportunities than ever for packaging with a comparatively lower cost of production.
These adhesives can be applied with a variety of systems. The application equipment is almost as varied as the adhesives them selves. Primary these systems fall into two basics types. Hand held, using sticks slugs or cartridges, and bulk systems which can usually accept a wide variety of forms of adhesives. Handguns are used for low volume applications with low viscosity adhesives. The bulk systems include rollcoaters, bench top extruders, swirl spray systems and fiberization systems.
Roll coating machines are commonly used for the application of a liquid to the surface of a part.
Extruders process multiple kinds of materials in different volumes or quantities and in numerous ways, from single packer, twin packer, horizontal feed, terrier bottom feeder and twin screw extruders.
Swirl spray systems take the adhesive and pump it under pressure from a bulk heating tank through either a stationary or hand held applicator, which applies the adhesive in a circular pattern (swirl).
Fiberization guns offer non-contact lamination capabilities by oscillating small fibers of the adhesive at high speed simultaneously. The majority of these systems precisely control the temperature of the hot melt – allowing for their precise application.
Adhesives or glues are available in many different forms, dependent on the equipment they are to applied with or the specific application they are being used for. These forms include sticks, slugs, cartridges, chips, chunks, slats, powders, crystals, bricks and others.
This adhesive technology is a “quiet” industry, as it is a Whole Melt Extracts big component of production but something that the public isn’t familiar with. Large and small companies ranging from Kraft, Nabisco, Anheuser-Busch, Proctor & Gamble and hundreds more rely on this industry every day for the production and packaging of their products. Your local custom packaging and fulfillment operation also uses hot melts as a critical element of their package assembly process.
The next time you open a packaged food product, tear apart a sealed bag or unwrap a box with something you ordered online, consider that you’re experiencing something that’s been made possible with hot melts.