Irgacure 819 is one of BAPO type photoinitiators, which absorbs longer wavelength UV light in the near visible region above 430 nm. Light of this wavelength penetrates deeper into the thicker layers of the coating, thus enabling the through curing effect. Shorter wavelength light, around 230 nm, is of higher photon energy but is less penetrating than that of longer wavelengths. Light of this shorter wavelength is particularly useful for surface curing.
Moreover, Irgacure 819 also allow UV absorbers to be formulated into the coating for improved outdoor weatherability. In addition to excellent through cure properties, BAPO photoinitiators photobleach after UV exposure to give a clean white appearance in contrast to the off-white color associated with other long wavelength absorption photoinitiators.
Based on the above facts, Irgacure 819 is widely used in UV-curable formulations for clear or white systems, also for pigmented formulation. It is especially used for curing thick films with good through cure performance.
Advantages of Irgacure 819
- Low yellowing when exposed to sufficient amounts of UV radiation.
- Good absorption of long wavelength UV light, which makes Irgacure 819 suitable for curing thick coatings.
- Has photobleach effect after UV exposure.
- Low volatility and low odor makes Irgacure 819 an environment friendly products.
- High initiating activity and good solubility.
All the above properties of Irgacure 819 make it a versatile UV photoinitiator. It can be used in both white and pigmented systems, and particularly for curing thick films. In order to achieve the best curing effect, Irgacure 819 is often used with other photoinitiators such as Irgacure 184, Irgacure 369, Irgacure 2959, Darocur 1173, Irgacure 907, etc.