Self-initiated UV-curable polyacrylate using soybean isolate as hydrogen donor

Abstract

Using the seed emulsion polymerization method, photoinitiator 4-hydroxybenzophenone (HBP) and co-initiator soy protein isolate (SPI) were simultaneously grafted onto a polyacrylate molecular chain, and an innovative UV-curable waterborne polyacrylate resin based on biomass SPI-HBP macromolecular photoinitiator system was prepared, which can be rapidly self-initiated. It was successfully developed into a type of waterborne coatings with excellent mechanical properties for woodware. The results showed that the PA-SPI-HBP composite emulsion showed good UV absorption performance near 284 nm, where the absorbance of the photoinitiator decreased to 73.71 % of the initial value under UV light exposure for 1 min. With an increase in HBP content, the UV curing time of the coating was shortened from 10.68 s to 5.18 s. When the addition of HBP was increased from 0 % to 4 %, the tensile strength of the films increased from 1.85 MPa to 16.39 MPa, the tensile modulus of elasticity increased from 2.88 MPa to 374.81 MPa, and the elongation at break decreased from 559.03 % to 38.46 %. This study provided a new method for the preparation of biomass-derived macromolecular photoinitiators and highly efficient self-initiating UV-curable wood coatings.