As part of our diploma thesis, we investigated which photoinitiators and in what concentrations satisfactorily cure wood coatings after exposure to a UV-LED light source. We tested seven different photoinitiators with four different concentrations for a total of 28 different samples. All samples cured with UV-LED technology were evaluated according to various predefined criteria. As expected, the samples with a higher concentration of photoinitiator cured better than those with a lower concentration, and a difference between individual photoinitiators was also shown. Photoinitiators A, B, C, E and F cured satisfactorily, while photoinitiators D and G are not suitable for curing as independent photoinitiators. We also supported the results with analytic tools, where we compared the sample cured with UV-LED technology with the sample cured with classic UV technology using gas chromatography and proved that in UV-LED curing it is necessary to use photoinitiators which are suitable for UV-LED lamps of specific wavelengths. In addition to good curing, other properties are also important when choosing the right photoinitiator, such as price, market availability, method of incorporation into the coating and yellowing immediately after curing. We tested the yellowing on five samples: A50, C50, E50, F5 and F15, for comparison we also tested the photoinitiator used in standard formulations of UV-curable coatings. We found that the yellowing of photoinitiator F was too high, and therefore not suitable for white pigmented coatings.
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