Making labels stick in difficult situations
- New HERMA adhesive 65Tpc makes labels compatible with an exceptionally diverse range of "difficult" surfaces.
- Labels coated with 65Tpc stick to expanded polystyrene, polyurethane, rough PE canisters, tyres, metal castings, wooden pallets, concrete, carpet backing, uneven fruit skins, and other materials.
- HERMA multi-layer technology facilitates use of a dispersion adhesive – free from plasticizers and without the risk of bleeding.
Some surfaces still cause major headaches if a label is to be applied. If the substrate is too rough, rubbery or variable, a conventional label will soon fall off – provided that it can be attached in the first place. And the available adhesives that are suitable for a few challenging surfaces often give rise to unpleasant side effects, such as bleeding of the adhesive or severely soiled tools, when they are being processed, typically during die-cutting or dispensing. Thanks to its innovative multi-layer technology, HERMA has now developed a plasticizer-free, acrylate-based dispersion adhesive that is compatible with an astonishing variety of "difficult" surfaces. The 65Tpc adhesive offers outstanding processing properties, sidestepping the drawbacks that can be associated with formulations for such surfaces. A broad array of materials, including polyurethane and expanded polystyrene, rough PE canisters, tyres, metal castings and wooden pallets, no longer present an insurmountable challenge.
"We initially focused on tyre labelling," explains Dr. Ulli Nägele, HERMA's head of development. "As with many synthetic materials, the problem lies in the low-energy surface, especially in combination with the carbon black particles that are contained in tyres." Until recently, practically the only way to get anything to stick on a tyre was to use label stock with a thick coating of a rubber-based hot-melt adhesive. This formulation in particular regularly gave rise to complications, both when producing the labels and when dispensing them.
Entirely plasticizer-free
"Although the HERMA 65Tpc adhesive also has a fairly high coat weight, a special second layer endows it with high cohesive (internal) strength. This significantly reduces adhesive bleeding, so that the coating can be applied to the whole of the label without omitting certain areas or the edges," explains Dr. Nägele. Since the dispersion adhesive does not contain any plasticizers, it does not attack or bleed through either the surface to which the label is attached or the label itself. The development project quickly revealed that the 65Tpc adhesive, in view of its extremely high initial tack and final adhesion, is highly suitable not only for tyres, but also for many other critical surfaces. Apart from those already mentioned, these include various plastic and foamed materials, aluminium checker plate, concrete, carpet backing, and even the rough skins of some fruits, such as the cantaloupe and other netted melons. The 65Tpc adhesive has been approved by the German test institute ISEGA for contact with dry, moist and non-fatty foodstuffs. It is available in combination with a range of paper and film label stock.