new adhesive technologies
BASF has developed an adhesive coating technology that allows up to three different layers of adhesive to be applied simultaneously onto a carrier material using a multilayer die. When coating adhesive labels, for example, an oxygen barrier or UV absorbent layer can be integrated between two layers of adhesive without requiring three individual production stages. Manufacturers of pressure sensitive labels — including those with in-house coaters — can lower their production costs and save manufacturing time, the company claims.
The multilayer coating process is also said to make it possible to manufacture clear-to-clear laminates with BASF’s acResin adhesives at over 1,312 feet per minute. They are UV cross linkable acrylate hot melt pressure sensitive adhesives. They are water and solvent-free and claims to offer advantages over conventional adhesives, both in processing and in environmental terms.
Irradiation with UV light controls the cross linking of the macromolecules in the adhesive film, which is responsible for the adhesive properties. If the polymers are highly cross linked, the adhesive film is relatively firm and holds together when subjected to tensile loading. The contact between an object and the adhesive gives way first, allowing the easy removal of a price label without leaving a residue for example. Conversely, if the polymer chains are weakly cross linked, they will break down before the adhesive detaches from the surface and a residue will remain on the surface. With acResin, the adhesive strength of the adhesive layer can be varied according to the UV dosage deployed.