Hotmelt adhesives are based on different raw materials and are processed when hot. Most common are adhesives based on ethylene vinyl acetate (EVA) that pertain to thermoplastics and can therefore be repeatedly melted. Adhesives based on polyurethane (PUR) on the other hand harden chemically and ensure a lasting bond.
Both types are used on edgebanding machines for the bonding of plastic, paper and veneer edgings. Depending on the type of machine, the use of granules or the relevant hotmelt adhesive cartridges is necessary. The small 2.5 kg bags and the possibility to purchase single cartridges make it easier to quickly switch to different colours.
Waterproof? Choose PUR!
If the bonding is particularly demanding, you should change to PUR hotmelt adhesives. This reactive adhesive does not only set physically by solidifying, it reacts chemically with the humidity of the surrounding air as well as the remaining humidity in the workpiece. This crosslinking creates a particularly high heat and water resistance.
Moreover, the glue line will be more resistant against solvents and cleaners. PUR is especially suitable for overpainting.
Compare the range of the common adhesive technologies:
Did you know? PUR adhesives can be processed on almost all systems without additional equipment. Let your Ostermann representative advise.
Joint appearance in damp conditions
filled vs unfilled
The filled EVA adhesive can still be called the „classic“. It has lots of positive characteristics, such as the easy and uncomplicated handling, the simple cleaning of the machine and a nice bondline.
Due to mineral components, stringing is reduced and the adhesive can be easily applied with a standard roller. The „classic“ will forgive small mistakes.Filled EVA adhesive
The further development of the filled adhesive resulted in the unfilled variant. In the latter, the mineral fillers were deliberately left out to create a thin bondline with the remaining pure resins. The glue consumption can be reduced at the machine.
Ostermann recommends the transparent test edging to help find the correct amount of adhesive and correct the application.Unfilled EVA adhesive
The best adhesive will be no good…
… if the pre- and post-processing of the board isn‘t up to scratch. Therefore, you should always make sure that all blades and cutters are sharp..
Slight damages in the board surface of a poorly edged board are enough to create weak spots that allow humidity to seep in. The spacer, the pinch roller and the scraper aren‘t adjusted well either? Which units need the right cleaning agent? Ostermann‘s technical sales consultants are happy to help