Photoinitiator, Ultraviolet (uv) Curable Ink Curing Speed, Pigment

UV ink has been broadly used in printing industry because of its fast curing rate, no pollution, high printing quality. The curing rate mainly affected by photo-initiator and pigment is an important factor of UV ink. The curing process of UV ink depend on photoinitiators absorb radiant energy form radicals or cationic that initiate monomers or pre-polymers to polymerize, cross-link and graft react and form 3-dimensional cross-linked networks ,then the curing process is finished on the other hand , the different pigments in the inks absorb .reflect and scatter ultraviolet in different degree. The absorbed ultraviolet make the exciting state of the photoinitiators quench,then pigments exert an effect on the curing process of UV ink. Both photoinitiators and pigment are important factors of the curing rate at the same time.The four color screen UV inks are made by changing the types and quantities of 9 types of photo-initiators and 11 types of pigments under the same conditions. The effects of photo-initiators and pigments on UV ink are studied by the spectrum absorption curves of all the pigments, the curing speeds and the densities of different pigments.The results of the studies proved that the curing speed of UV ink is seriously affected by photo-initiators and pigments. In order to promote the curing rate of UV ink, the choosing of photo-initiators and pigments is most important. In order to choose the most favorable photo-initiator and pigment, the spectrum absorption characteristics must be matched with each other and matched with the light source at the same time, that is the absorption peak of the pigment must be in the "spectrum window". The effect of pigments on the curing rate of UV ink is mainly because of its absorption to ultraviolet. The curing rate depend on the types of pigments. The color of the pigments is the most important factor, the effect on curing rate according its order is:Red ink>Yellow ink>Cyan ink>Black inkThe content of the photo-initiator and the pigment must be proper. The content of the pigments is best lower under the condition of proving the printing density.There is the conclusion of this studies : the photo-initiator 819 is best matched with the pigment BK2 ,the optimum content of the pigment is about 7%; the photo-initiator ITX is best matched with C3,the optimum content of the pigment is 6%,the photo-initiator ITX is best matched With M, the optimum content of the pigment is 6%The result proved that the curing rate ,printability, printing quality of the UV screen photo CD ink made from the former formula are all well can replace the import ink completely.