Formulational Properties of a Newly Developed Low Viscosity Diacrylate-Functional Epoxy-Based Oligomer

The main component of any UV-polymerizable formulation is the oligomer.  However, most of the commercially available oligomers possess very high viscosities, often in excess of 10⁶ cP.  This creates significant problems for formulators who must handle these materials.  Thus, an effective method of reducing oligomer viscosities without changing the fundamental properties is desirable.  Researchers here recognized in recent years that adding very small amounts of water to an acrylate-functional epoxy-based oligomer could reduce its viscosity by more than 80%.  Their work indicated water to be a more effective diluentthan two of the most effective reactive monomers used today.  The results of this work were recently reported at the 2012 RadTech International UV&EB Conference in Chicago. 

Having demonstrated the surprisingly large effect of water on viscosity, further work was initiated to evaluate the formulational properties of this new low viscosity oligomer to insure that water is not detrimental to the final polymer film properties.  Several UV-polymerizable formulations were prepared using this oligomer along with several functional monomers and a photoinitiator.  Similar control formulations were prepared using the neat oligomer.  The viscosities were measured and then thin polymer films of each were prepared using UV irradiation.  These films were then characterized for their thermomechanical properties using dynamic mechanical analysis (DMA) technology and comparisons were made of the properties of these four formulations.  The purpose of this presentation is to report the results of this recent study and to communicate the apparent value of this approach to oligomer viscosity reduction.