Dustin B. Martin

Cationic UV-cured coatings containing epoxidized soybean oil initiated by new onium salts containing tetrakis(pentafluorophenyl)gallate anion

Different formulations containing epoxidized soybean oil (ESO) and a commercial cycloaliphatic epoxy resin (UVR6110) were cured by onium tetrakis(pentafluorophenyl)gallate (Gallate) on steel panels. The resulting coatings were clear and their mechanical properties were tested by the Sward hardness test, cross-hatch tape adhesion test and MEK double rub test. The new initiators have the advantage of good solubility, high reactivity, and the production of colorless coatings. The best formulations obtained contain 50% ESO, 50% UVR6110, and 0.5% silwet if sulfonium gallate is used as initiator, and 60% ESO, 40% UVR6110, and 0.5% silwet if iodonium gallate is the initiator.

Synthesis and study of iodonium borate salts as photoinitiators

Iodonium butyltriphenylborate salts (AI+Ar′Ph3B−R), (Bu) were found to be more efficient than iodonium tetraphenylborate salts (RPh) when used as photoinitiators for the polymerization of acrylates. Relative photodecomposition rates were also different. It was found from a study of the photoreaction of iodonium borate salts with a model monomer, methyl methacrylate, that iodonium butyltriphenylborate salts simultaneously produce a butyl radical from the borate anion and an aryl radical from the iodonium cation upon irradiation. Both radicals initiate polymerization. Iodonium tetraphenylborate salts were found to release an aryl radical, but only from the iodonium cation. Iodonium borate salts exhibit strong absorption below 300 nm with a tail absorption above 400 nm. Thus, iodonium butyltriphenyl borate salts are efficient photoinitiators even when used with visible light. When a photosensitizer such as 5,7-diiodo-3-butoxy-6-fluorone is employed, iodonium butyltriphenylborate salts are rendered much more efficient for visible light photopolymerization.