What does the amount of photoinitiator component affect the UV ink?
Photoinitiator is also an important component of UV ink, which determines the light curing rate of UV ink. The choice of photoinitiator should first consider the absorption spectrum of the photoinitiator to match the emission spectrum of the UV light source. The UV light source is mainly used for the medium-pressure mercury lamp, its emission spectrum in the UV region of 365nm, 313nm, 302nm, 254nm and other wavelengths have a strong emission intensity, many photoinitiators in the above wavelengths have a large absorption.
UV ink is a colored system composed of pigments, because the pigments have absorption, reflection and scattering of ultraviolet light, different colors of pigments on the absorption and reflection of ultraviolet light is not the same, will affect the UV ink photoinitiator absorption of ultraviolet light, thus affecting the UV ink light curing rate, so the UV ink formulation of the choice of photoinitiator Particularly important, to use the pigment UV absorption by the minimum impact of the photoinitiator.
Pigment absorption in the UV region of the smallest wavelength zone commonly known as the pigment “window”, this wavelength zone UV light through the most, the most favorable photoinitiator absorption. In order to give full play to the synergistic effect of different photoinitiators, in UV ink often choose more than two kinds of photoinitiators used in conjunction with each other, in order to make full use of the UV light source emitted by different wavelengths of UV light and pigment “window” to provide the transmission of UV light, to achieve the minimum amount of photoinitiator, made of light curing rate of the fastest UV ink.
UV ink commonly used photoinitiators are BP, 651, 1173, 184, MBF, ITX, 907, 369, TPO and 819, they are free radical light curing photoinitiators, of which 651, 1173, 184, MBF, 907, 369, TPO and 819 are cracking photoinitiators, BP and ITX for the capture of hydrogen type photoinitiators. .
Here we have to point out that white UV ink generally choose TPO or 819 and 184 with the use of TPO and 819 are acyl phosphine oxide photoinitiators, photoinitiating activity is high, there is a long UV absorption wavelength, there is a photobleaching effect, suitable for a variety of pigment light curing, especially white pigment titanium dioxide. 184 is a class of yellowing-resistant photoinitiators, with TPO and 819 with the use of excellent UV white ink curing. Use, the UV white ink curing excellent.
In addition, the photoinitiator methyl benzoylformate (MBF) is a better yellowing resistance photoinitiator, less used in the past, MBF and TPO or 819 with the use of UV white ink, its light curing rate and yellowing resistance are better than 184 and TPO or 819 combination, so especially suitable for white UV ink and light color UV ink production use. Black UV ink because of its pigment is mainly carbon black, almost all absorption of UV light, must be used with efficient photo-initiated system, currently it is believed that 369 and ITX with TPO or 819 is the best.
UV Photoinitiator Same series products