Surlyn is the most effective, forgiving sealant layer ever invented. What makes it so effective ? Why the search for alternatives?
Surlyn's properties derive from what is called an ionomer bond. An ionomer of sodium or zinc in limbo share with the orbit of polyethylene molecules. This delivers unsurpassed tack and toughness and strength. Surlyn seals through contaminants better than any other resin. This is very important in the large market for subprimal meat packaging.
Surlyn's is expensive and difficult to process. Plastic film plant managers were early adaptors of metallocenes because Surlyn is hydroscopic and corrosive to extruder screws and barrels. Surlyn has to be dried before extruding. It is incompatible with other common polyethylene resins.
Metallocenes deliver almost the same hot tack characteristics without the aggravation. Metallocenes are plug and play. No drying, no corrosion and lower cost.