Synthesis And Performance Test Of An Acrylate Polymer Photoinitiator

Macromolecular photoinitiators have been widely used in food packaging inks.Compared with small molecule photoinitiators,it has the advantages of low odor,low volatility,low migration and high compatibility.In this paper,three double bonds-containing photoinitiators were synthesized by two routes and tested.They have similar structures but the number of ethoxy groups between benzophenone and acrylic acid is 1 to 3 respectively.This double bond-containing photoinitiators are respectively subjected to free radical copolymerization or self-polymerization with acrylates such as butyl acrylate to obtain several macromolecular photoinitiators with different side chain lengths and different copolymerization ratios.In this paper,RT-FTIR was used to study the influence of the side chain length and copolymerization ratio of the synthesized macromolecular photoinitiator on the polymerization kinetics.The results show that:? In the length of the side chain,the number of ethoxy groups is between 1 and 2,The polymerization rate and double bond conversion rate increase gradually with the number of ethoxy groups due to the decrease of macromolecule rigidity and the easy movement of initiator groups.But,when the number of ethoxy groups is between 2 and 3,the steric hindrance of the ethoxy group to the initiator reduces the polymerization rate and double bond conversion rate.?The content of initiator group in macromolecular photoinitiator is in the range of 100%78%,macromolecule rigidity is reduced,initiator group is easy to move,which improves the polymerization rate and double bond conversion rate.But in the range of 78%-51%,there are too many butyl acrylate pairs on the molecular chain,increased steric hindrance,reduced contact with double bonds,and reduced polymerization rate and conversion rate.This article compares the varnish performance of macromolecular photoinitiator PPI-5 with the polymerizable initiator PI-1 and the small molecule photoinitiator IHT PI-106.The results show that when equimolar initiator groups are used,the pendulum hardness,yellowness,surface dry and adhesion of the macromolecular photoinitiator after curing are similar to those of the other two photoinitiators.The migration test of the three initiators shows that since the initiator group of the macromolecular photoinitiator is fixed on the macromolecular chain,its initiator migration is significantly lower than the other two photoinitiators.