Herma adds colored adhesive for opacity

Introduced at Labelexpo Europe 2017, HERMAperfectOpaque features the company’s multi-layer technology to allow most label materials to be turned opaque without affecting the properties of the adhesive. Two different adhesives will be available initially – HERMAperfectOpaque 62Gpo and HERMAperfectOpaque 62Dpo. In addition to providing migration safety, 62Gpo is said to be suitable for applications requiring extremely high tack despite damp and cool conditions. 62Dpo is suited for production of opaque copy/laser labels, and prevents bleeding over the die-cut edges during label conversion. In both cases, the second layer is colored with dark blue pigment.

Herma explained that label printers and users have had to make compromises in cases where nothing must show through the label material, with either the choice of a suitable colored label material for a limited range or using a material with a colored adhesive. Due to the soot particles usually contained in the latter, Herma said these adhesives have different qualities than conventional types, and are not at all suitable for direct contact with foodstuffs.

‘Coloring the adhesive is not a completely new idea,’ explained Dr Ulli Nägele, head of research and development at Herma. ‘However, the prevalent use of soot inevitably changed the adhesive properties of conventional, one-layer adhesives. Until now, it was also unthinkable for such colored adhesives to receive the approval for direct contact with foodstuffs.

‘Employing our multi-layer technology, we color only the second layer – with a new pigment that is suitable for direct contact with foodstuffs. The adhesive layer immediately affecting the substrate remains unchanged.’

As the adhesive layer immediately affecting the substrate is made from proven standard adhesives, HERMAperfectOpaque can be used without requiring time- and labor-intensive adhesion and processing tests, with label materials and adhesives able to be combined to achieve optimal opacity for various applications.

Using a dark blue color for the second layer maintains the whiteness of labels, as Nägele explained: ‘Tests in our development lab have shown that while it is not possible to increase opacity with black pigment, this color also affects the whiteness of the label material. In our opinion, dark blue is a better choice since it maintains the whiteness.’

Herma added that as well as films and paper, the new range is suitable for thermal eco adhesive materials, with its multi-layer technology making it possible to produce opaque thermal adhesive materials without any compromises regarding adhesion. Moreover, HERMAperfectOpaque makes it possible to produce opaque thermal eco adhesive materials that do not require a barrier layer (reverse side coating), and unlike soot, the new color pigments do not influence the thermal reaction.

Nägele concluded: ‘In view of the wide range of products and packaging materials, label printers gain an important advantage through the extra flexibility provided by our new solution. This applies to label materials that can now be used as well as application safety.’

Read L&L's comprehensive Labelexpo Europe 2017 preview in issue 4