Replacing FT Wax with Epolene®

Replacing Fischer-Tropsch Wax

Fischer-Tropsch wax , or FT wax, is commonly used in EVA and metallocene based hot melt adhesive formulations to adjust set time and viscosity.  The problem with FT wax is that the supply chain is fragile and there is a constant concern amongst adhesive manufacturers about a global shortage.  Recent shortages have led adhesive manufacturers to search for an alternative in order to reduce the overall use of FT wax in their formulations.

Epolene® - An Alternative to FT Wax

In response to requests from hot melt adhesive formulators, Westlake Chemical has evaluated hot melt adhesive formulations with reduced FT wax.  In these formulations the FT wax has either been partially or completely substituted with Epolene® N-14 or Epolene® N-21.  The formulations that were tested are listed in the table below.
 

Formulated Adhesive Comparison

The performance and properties of the adhesive formulations above were tested for the following properties:
  • Peel Adhesion Failure Temperature (PAFT)
  • Shear Adhesion Failure Temperature (SAFT)
  • Low temperature fiber tear
  • Open Time @ 177°C
  • Set Time @ 177°C
  • Melting Temperature (Tm)
  • Crystallization Temperature (Tc)
  • Brookfield Viscosity @ 149°C and 177°C

The properties of each hot melt adhesive formulation are compared in the graph below.
 

Adhesion & Cohesion

All of the formulations resulted in hot melt adhesives with similar PAFT, SAFT, and low temperature fiber tear.  Full or partial substitution of FT wax with Epolene® is possible without any negative effects on the adhesive and cohesive performance of the formulation.

Open & Set Time

Substitution of FT wax with Epolene® resulted in hot melt adhesive formulations with a slightly longer open time.  Interestingly, complete substitution of FT wax with Epolene® N-14 resulted in the formulation with the most similar open time as the full FT wax formulation.  The set time of the adhesive formulations were relatively unchanged by substitution of FT wax with Epolene®.

Thermal Analysis

Partial and full substitution of FT wax with Epolene® N-14 resulted in a hot melt adhesive with a very similar thermal profile as the full FT wax formulation.  When FT wax was substituted for Epolene® N-21, however, the melting temperature of the resulting formulation was significantly higher than the full FT wax formulation.  The crystallization temperature of the formulations was unaffected by substitution of FT wax with Epolene®.

Viscosity

The viscosity of the hot melt adhesive formulation was slightly increased when FT wax was substituted with Epolene®.  The largest increase in viscosity was seen when FT wax was completely substituted with Epolene® N-14.

Summary & Conclusion

Finding a suitable replacement for Fischer-Tropsch wax in hot melt adhesive formulations has become more important as the supply for these hard waxes has become more and more unstable.  Epolene® polymers are polyethylene waxes that have shown to closely match the performance of FT wax without having a negative impact on hot melt adhesive properties.  Epolene® N-14 and Epolene® N-21 provide similar performance in hot melt adhesive formulations as FT wax and are recommended as a substitute for Fischer-Tropsch wax.

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