Effect of high corona dosage on laminate bond strength and time dependent behavior of surface energy on PE, PP and PET
How long does a corona treatment last? How strong is the effect of an overtreatment? How does this affect laminate bond strength? Those questions arise frequently during corona treatment of polymer films.
Therefore, scientists from Fraunhofer Institute for Process Engineering and Packaging led by Martina Lindner, evaluated how an increased corona dosage affects the surface energy, how strong is the time dependent decrease of surface tension and if this decrease is affected by the dosage. PE, PP and PET films were used as polymeric substrates.
The scientists observed, that increased corona dosages lead to a stronger increase of surface energy on PE film than on PP and PET, even when dosages above the recommended levels were applied. The time dependent decrease of surface energy took up to 140 and more, dependent on the polymer. However, it was independent on the corona dosage.
Strikingly the proportion of polar and disperse forces shifted towards the dispersive forces. Accordingly, the adhesion and wetting properties for dispersive and polar lacquers and adhesives are likely to change. Interestingly, the corona treatment did not have a negative effect on laminate bond strength of laminated PE and PET films. On PP a contrary effect was observed. The relating publication is available under http://onlinelibrary.wiley.com/doi/10.1002/app.45842/pdf.
