Bio-based Hot Melt Adhesives – The Components and Applicability

The COP-26 (UN Climate Change Conference) in Glasgow has come to an end. Many leaders spoke about the importance of keeping the global temperature rise to 1.5°C by 2030. De Monchy is actively contributing to a more sustainable future, by focusing on growing the percentage of sustainable products and applications in our portfolio.

The number of possible applications for bio-based packaging adhesive systems is growing. At the same time, various questions are raised within the market. What’s the difference between fossil-based- and bio-based Hot Melt Adhesives? When and why should and/or could I choose the more sustainable alternative?

Components of a Hot Melt Adhesive

Hot Melt Adhesives have been invented around the 1940’s as a solution to water-based adhesives, because they often failed in high humid climates, causing the packages to pop open. It is named ‘hot melt’, because heat is used to bring a solid adhesive (mostly in the form of a pastille) to a liquid phase. Most packaging adhesive systems are Hot Melt Adhesives.

A typical standard Hot Melt Adhesive contains of 3 components:

• 45% Tackifier (hydrocarbon or bio-based rosin ester),
• 35% Polymer (EVA, metallocene PO or APAO)
• 20% Wax (mainly Fischer Tropsch wax and other waxes such as paraffin and PE wax).

For the Hot Melt Adhesive to be labeled as ‘a bio-based Hot Melt Adhesive’, it must contain a certain percentage of bio-based components e.g. based on EN 16785-1, one of many classifications. Depending on the type and percentage of bio-based components used, a high level bio-based content can be achieved. An example of bio-based alternatives:

• Tackifier:             Rosin-ester or Terpene resins
• Polymer:            Bio-based polymer produced with ethanol from sugarcane
• Wax:                   Based on hydrogenated rapeseed, palm and castor oil and biobased PE wax.

In addition to the above components, the use of Thermoplastic Polyamides can be considered. With renewable content around 75%, the product itself acts as a strong hotmelt adhesive. Thermoplastic polyamides are available in various softening points, open times, flexibility and strength. Furthermore, they have high thermal stability and offer good adhesion to a broad range of substrates.

Applications

There is a difference between the applications of fossil-based- and bio-based Hot Melt Adhesives. Fossil-based Hot Melt Adhesives have better adhesion properties and heat resistance and can therefore offer  wider applicability, like woodworking, upholsteries and automotive applications. Nowadays, Bio-based Hot Melt Adhesives are mainly used in packaging applications, such as take away food packaging, tray forming and cardboard boxes.

The cost of a bio-based Hot Melt Adhesive is higher than its fossil-based alternative. However, pricing really depends on which bio-based components are used to produce the bio-based Hot Melt Adhesive. Prices of hydrocarbon resins and rosin esters in general do not differ a lot.

The benefits of bio-based

Most hot melt application machines can be used for both fossil-based and bio-based packaging adhesives. The benefits of bio-based Hot Melt Adhesives are, to name a few:

• Great performance: the bonding performance of bio-based Hot Melt Adhesives remains strong across wide ranges of substrates, especially on cardboard.
• Broad temperature range performance including deep-freeze.
• Easy conversion: bio-based Hot Melt Adhesives can be applied using the same equipment used with fossil-based Hot Melt Adhesives. This makes shifting between hot melt products less costly.
• Designed to use at lower processing temperatures of 150 – 170 °C.

Want to know more about raw materials as used in bio-based Hot Melt Adhesives?

You may still be wondering what the benefits are of renewable raw materials as used in bio-based Hot Melt Adhesives. Please contact Jacques Everaert for more information.