Pulse launches free radical ink for shrink to 70 percent

Bristol, UK-based Pulse Roll Label Products has launched FlexWrap: a UV flexographic ink formulated for use on shrink sleeve substrates. Two formulations are available: one with high chemical resistance for industrial applications and another that is food industry compatible.

Gary Seward, managing director, said: 'FlexWrap is a free radical ink formulation that provides excellent resistance to water which is imperative in steam shrinking. We have overcome the issues normally associated with this type of chemistry where the tendency was for the cured inks to become brittle leading to cracking and loss of adhesion. The alternative has been to use costly cationic formulations that require longer curing times and limit productivity. We have also overcome the potential for migration of the ink in food packaging through working within the parameters set by the major food manufacturers. FlexWrap can run at high production speeds and achieve as much as 70 percent shrinkage with very strong colors.’

Martin Addicott of Pulse Speciality Products added: ‘Adhesion of free radical inks has proved to be problematic on shrink sleeve material in the past. As recently as five years ago, under heat or steam shrink to 70 percent, inks would have been seen to fracture and flake away from the substrate demonstrating the inability to shrink and lack of adhesion. The phenomena of adhesion on shrink films is complex in that many, common, free radical materials can have a “solvent” like effect on the surface of the film. Surface energy is clearly a factor but requirements vary on a film type-to-type basis. Pulse has overcome these issues with the application of novel formulating technologies that create a strong bond to the common films used (OPS, PET & PVC). The core formulation has been developed in conjunction with raw material suppliers and with the assistance of the printer whose improved understanding of the process is key to achieving the desired results. Through this partnership there has been significant progress in the understanding of the interaction of film, corona treatment, heat management on press and ink formulation resulting in production, to a consistently high standard, with the FlexWrap series of inks. Acid and alkali resistance can also be achieved with suitable pigment selection.’