Fischer–Tropsch wax, or FT wax, is a petroleum-derived hydrocarbon wax commonly used in EVA- and metallocene-based hot-melt adhesive applications to adjust melting point, set time, and viscosity. FT wax sometimes poses issues for formulators because its supply chain is very volatile, produced by only a few manufacturers as a product of gas-to-liquids (GTL) processing of synthesis gas to synthetic liquid fuels. As such, adhesive manufacturers using FT wax are concerned that crude oil demand may lead to global shortages. Recently, shortages have caused adhesive manufacturers to search for an alternative wax to reduce the overall use of FT wax in their formulations.
EPOLENE® - An Alternative to FT Wax
EPOLENE® polymers are polyethylene waxes domestically produced by Westlake in Longview, Texas. Westlake is a leading chemical manufacturer of specialty polymer waxes. EPOLENE® wax, unlike FT wax, is produced on purpose and not as a byproduct of gas-to-liquids processing. This makes EPOLENE® a much more reliably sourced wax than Fischer–Tropsch wax. In response to requests from formulators with hot-melt adhesive applications, Westlake has evaluated EVA - and metallocene-based hot-melt adhesive formulations with EPOLENE® wax as a substitute for Fischer–Tropsch wax. In these formulations, FT wax content has been partially substituted with EPOLENE® N-37 and evaluated for performance comparison. The formulations with varying EPOLENE® content are listed in the table below.
Formulated Adhesive Comparison
The performance of the adhesive formulations above was tested for the following properties:
Peel adhesion failure temperature (PAFT)
Shear adhesion failure temperature (SAFT)
Open time @ 177°C
Set time @ 177°C
Brookfield viscosity @ 150°C and 177°C
High- and low-temperature fiber tear
The properties of each hot-melt adhesive formulation are compared in the graph below.
Adhesion & Cohesion
All the formulations containing EPOLENE® wax resulted in hot-melt adhesives with similar PAFT and SAFT. Full or partial substitution of Fischer–Tropsch wax with EPOLENE® wax 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 similar open time and set time.
Viscosity
The viscosity of the hot-melt adhesive formulation was slightly increased when FT wax was substituted with EPOLENE®. Larger viscosity increases are observed with higher amounts of EPOLENE®. Despite this, viscosity remained within a workable range for the hot-melt adhesive formulation.
Fiber Tear
Fiber tear tests were conducted at varying temperatures to compare the durability of the hot-melt adhesive applied to corrugated board when exposed to both low and high temperatures, like those encountered during package transit. The results of this test are shown below, where significant improvements were made to low-temperature performance, while high-temperature performance was largely comparable.
Summary & Conclusion
Fischer–Tropsch wax is a key component in hot-melt adhesives to adjust properties such as set and open time, melting point, and viscosity. Finding a suitable replacement for Fischer–Tropsch wax in hot-melt adhesive formulations is more important when this wax becomes supply constrained. EPOLENE® polymers are polyethylene waxes produced domestically in Longview, Texas, by Westlake, a leader in polyethylene waxes and specialty chemicals. EPOLENE® N-37 has been shown to match the performance of Fischer–Tropsch wax closely without having a negative impact on hot-melt adhesive properties and is recommended as a substitute for Fischer–Tropsch wax. Click below to request a sample of EPOLENE® wax for your hot-melt adhesive applications today.
