Highly Water‐Soluble Alpha‐Hydroxyalkylphenone Based Photoinitiator for Low‐Migration Applications

• Published in: Macromolecular chemistry and physics 2017-07, Vol.218 (14), p.n/a
• Main Authors: Roth, Meinhart, Hennen, Daniel, Oesterreicher, Andreas, Mostegel, Florian, Samusjew, Aleksandra, Edler, Matthias, Maier, Eugen, Griesser, Thomas
• Format: Article
• Language: English
• Subjects: low‐migration; photo polymerization; photoinitiator; water‐soluble
• ISSN: 1022-1352; 1521-3935
• DOI: 10.1002/macp.201700022

In this study, the bifunctional hydroxyketone based photoinitiator (PI) 1,1′‐{[(2,3‐dihydroxybutane‐1,4‐diyl)bis(oxy)]bis(4,1‐phenylene)}bis(2‐hydroxy‐2‐methylpropan‐1‐one) (Di‐PI) is synthesized with the aim to facilitate a highly photoactive water‐soluble PI which offers high migration stability. Di‐PI provides a five times higher water‐solubility than the state of the art water soluble PI 2‐hydroxy‐1‐[3‐(hydroxymethyl)phenyl]‐2‐methyl‐1‐propanone (I2959). Photo differential scanning calorimetry (Photo‐DSC) measurements reveal that the curing speed and conversion of N‐acroylmorpholine (NAM) in aqueous solution containing 0.5 mol% of Di‐PI are only slightly lower than formulations containing the reference PI I2959 in a concentration of 1 mol%. Most importantly, Di‐PI offers almost identical activity in dipropylene glycol diacrylate (DPDA) as I2959, although its migration from cured DPDA is significantly reduced by a factor of 7.6 compared to I2959. A bifunctional hydroxyketone based photoinitiator is synthesized, which provides a five times higher water‐solubility than 2‐hydroxy‐1‐[3‐(hydroxymethyl)phenyl]‐2‐methyl‐1‐propanone (I2959). Although, this photoinitiator offers similar photoreactivity as I2959, its migration ability is significantly reduced.