Hot Melt Adhesive or Thermoplastic Adhesive, has long been considered a commodity that is a very small part of packaging costs. Therefore the reduction in use has been of little priority. With the recent dramatic increases in hot melt prices customers have looked at ways to reduce the use of hot melt adhesive in packaging applications such as case sealing and carton sealing.
One way to dramatically reduce hot melt adhesive consumption is to cycle the automatic applicator or gun so that the adhesive is applied in dots or elongated lines rather than long beads. The intermittent application can offer strong bonds and in many applications reduce the use of hot melt by as much as 50%.
In order to cycle the adhesive properly you must have the correct pattern controller with intermittent output signal capability. Also you must plan to increase the pressure to the nozzle to allow for instantaneous extrusion or flow from the nozzle. With the increased adhesive fluid pressure you will need to decrease the size of orifice size of the nozzle tip. Higher pressure and smaller nozzles allow for precise patterns without adhesive “Stringing” or “Angle Hair”.
The filters in your hot melt system and applicators must be kept clean and new modules, the valving portion of the gun, should be used. New modules with high performance seals are successfully cycling today at over 150 million dots before being replaced. This is 10 to 20 times the cycle life of older modules with basic internal seal configurations.
Another benefit of properly applied intermittent hot melt patterns in case and carton sealing is that the packages are more consumer-friendly. End users can apply the correct amount of peal pressure to the flap to open the case or carton. With high quality cartons, the package remains aesthetically intact after opening rather than shredded and torn. Finally, those with dexterity issues, especially the elderly, will find the opening of cartons easier.