For light-curing processes, adhesive needs to be translucent so that photoinitiators in the entire adhesive layer can decompose and start the crosslinking reaction. Because black absorbs the majority of light, the amount that is transmitted becomes naturally lower as the layer gets thicker.
However, the black dyed DELO DUALBOND GE4949 acrylate can be used for thicknesses of up to 500 µm. In addition to its light-curing component, it also contains a small humidity-curing portion, which triggers crosslinking even in small shadowed areas.
The acrylate is medium-viscous, has very good tension-equalizing characteristics thanks to a high elongation at tear, and achieves high strength on various plastics. It is particularly suitable for sealing and bonding for black components. This includes sealing wires, covering lettering, bonding clips or emblems, as well as sealing connecting terminals.
Also available for other adhesive chemicals
For the first time, DELO has also dyed light-activated epoxy resins black that even can be light-cured at thicknesses of up to 1 mm. Unexposed areas can be cured in a subsequent heat curing step. Possible applications for this include covering components for copy protection reasons or shielding against scattered light.
“Many customers request black adhesives that can be cured by light within seconds”, said Robert Saller, Director Sales International and Management Board Member at DELO. “That wasn't very easy, but we can now demonstrate some good results here. In the future, we will continue expanding our product range, particularly in the field of black, light-curing epoxy resins.”