LOW APPLICATION TEMPERATURE HOT MELT ADHESIVES

The application temperature of hot melt adhesives should be presented on the Product Technical datasheet, som other details such as brief summary of application and viscosity are also helpfull, even as the melting point. Optional data can be the composition of the hotmelt adhesive, it’s colour and form.

LOW APPLICATION TEMPERATURE HOT MELT ADHESIVES

There is a trend of low application temperature hot melt adhesives, but these may have some disadvantages. The typical temperature of standard hot melt adhesives in the packaging industry is 160°C, where the typical low application temperature hot melt adhesive is 120°C . The two main reasons to promote low application temperature hot melt adhesives are:

  • High performance on a wide variety of applications
    • Low application temperature hot melt adhesives require low melting point polymers. These polymers cover roughly only 25% of the polymer availability. With focussing on standard application temperature hot melt adhesive, the choice in base polymers increase with 75% to 100%. So more options if standard AND low application temperature are considered.
  • No fumes
    • High quality hotmelt adhesives do not fume at 160°C, even not at 180°C
  • Lower energy consumption
    • This is possible true, i tcould be a nice side affect, as long as low temperature application hot melts save in consumption (the amount) and line-efficiency as well (no machine stops or slower processing time of the packaging machine). It may be considered as “a drop in the bucket”.
  • Improved safety
    • It’s also a “drop in te bucket”, burns at 120°C are still very dangerous and safety measurements are equal to burns at 160°C. Rather invest in low adhesive consumption, maintenaince and training. Less machine interruptions would provide an increasing safetylevel more likely.
  • Average consumption reduction of 20 % versus  traditional hotmelt adhesives
    • True; against standard yellowish EVA. as most low temperature hotmelt adhesives are based on polyolefin. New polyolefin hot melt adhesives at 160°C even allow less adhesive consumption up to 60%. (so low temperature hot melt adhesives are 50% less effictive!)
  • Hassle-free maintenance
    • True; lower application temperature will give less coaling and hotmelt ageing by oxidation. But, high quality white EVA and high quality polyolefin will be stable at 160°C as well.

TEMPERATURE RESISTANCY

Many people assume the melting point of a hotmelt adhesive equals to the heat resistancy of a hotmelt adhesive on a packaging. As most hotmelt adhesives being thermoplastic, it will become more soft even far below the melting point. The melting point is only the physical point where the solid state becomes fluid. Another important temperature parameter of an hotmelt adhesive is the Adhesion Fail Temperature, this might be a Shear-SAFT and a Peal-PAFT.  This means, the temperature where an adhesive fails bonding under a load.

SOME TYPICAL TEMPERATURES OF PACKAGING HOT MELT ADHESIVES.

Adhesiveapplication
temperature
Melting
point
Adhesion
Fail
Temp.
Low application temperature hot melt120°C85°C38°C
Standard packaging hot melt160°C110°C50°C
High Heat resistance hot melt170°C110°C65°C

CONCLUSION

Low application temperature hot melt adhesives might be an option, but we advice rather to focus on the total packaging process, running more efficiënt. Furthermore the risk of an adhesion fail on regular transport especially in, to and over countries around the equator. Also bear in mind that during hot summers transport temperatures may become more and more often higher than 40°C even in countries that are not near the equator.

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