In the melt

The Dow Chemical Company has launched a new line of polyolefin polymers specifically developed for hot melt adhesive formulations and polymer modification applications.

Dubbed the Affinity GA Polyolefin Plastomers (POPs), they are suitable for hot melt adhesive applications such as packaging (case and carton sealing), disposable nonwovens (adult and infant hygiene products), and graphic arts (bookbinding).

Dow claims that the new high flow products provide hot melt users with a number of distinct processing and performance advantages compared to EVA-based adhesives, including reduced filter plugging, less machine wear and tear, improved colour and clarity, negligible odour, and decreased system downtime.

And unlike most traditional EVA-based adhesives, the new POPs can also bond over a broad range of temperatures, suiting them for reliably sealing cases and cartons. Affinity GA 1950 POP, for example, is designed for temperatures of 350 degrees F (177 degrees C) while GA 1900 POP combines aggressive bonding with improved thermal stability for low application temperatures of 250 degrees F (120 degrees C) to 275 degrees F (135 degrees C).

"An important technical difference between Affinity GA POPs and EVA-based adhesives is that EVA-based polymers have oxygen in the backbone, which can contribute to colour change and oxidation, and ultimately to poor sealing reliability," said Dow's Dr. Selim Yalvac. "Affinity GA POPs have no such oxygen in the backbone, making them much more stable and reliable for clean running hot melt applications."

They can also be used to modify the flow, flexibility, adhesion, and mechanical properties of a range of other polymers - allowing them to be used use in a range of other applications. Many plastic end products produced by injection moulding, extrusion, blow moulding or powder injection moulding can be enhanced by formulating with the POPs during compounding or processing operations.

In masterbatch applications, the high filler loading capabilities of the new POPs make them useful as carriers for hard-to-load colours and/or additives. With melting points around 158 degrees F (70 degrees C) they are able to preserve the integrity of temperature-sensitive additives. Additionally, the low viscosity of the POPs enables rapid dispersion in the end use compound.