Reactive Silicones as Cross-Linkers in UV Cured Systems

A wide variety of polymers are used as resins in coatings systems. Often defined by their reactive groups, the myriad of resins offer a wide-range of properties. In the coatings industry acrylate, epoxy, urethane and polyester coatings are all quite common and have associated typical properties and expectations. Resin manufacturers have spent countless hours and substantial money fine-tuning and expanding the properties of their core chemistry to vary their utility.2-7

One way to alter the fundamental properties of a polymer is to react it with a different polymer generating an AB type co-polymer or hybrid. With low surface energy, ultra low Tg , and strong slip, release and flow properties, polydimethylsiloxane (aka PDMS or silicone) can bring profound property changes to these hybrids.

PDMS itself has no reactive groups although the polymer can be broken under strong base or acid catalysis and reacted with nucleophilic resin systems. Siltech has available a portfolio of modified silicones with any of the reactive groups used in coatings. The reactive sites are made from the same raw materials as the native resin polymers.

However, the reaction is complicated by the inherent insolubility of silicone in organic resins. The reaction with silicones is often slower and requires stringent mixing methods or other techniques to make these materials miscible.

In the previous study1 we had shown that polyether modification of the silicones is usually necessary for miscibility and complete incorporation of the silicone into the film. In this study we look only at these soluble species.

In this paper, we modify the coatings films in situ with reactive silicones and examine the effect on their liquid and cured film properties. We have chosen UV cured acrylate and cycloaliphatic epoxy systems as examples, but this concept is valid in otherwise cured systems as well.