A solvent-free and scalable method to prepare alkali soluble soybean oil-based epoxy acrylic resin for photoresist application

The raw materials of commercial resin for photoresists nearly all come from petroleum resources. To follow the policy of “green chemistry”, it is urgent to employ renewable, biodegradable, green biomass resources instead of petroleum for the construction of photoresist resin. In this study, the alkaline soluble biobased epoxy acrylic resins are successfully prepared via a ring-opening reaction of epoxidized soybean oil (ESO) with the modified acrylic precursor (MMHEA), followed by diisocyanate modifying to introduce a small amount of polyurethane. The structures of the precursor and product resin are characterized and determined by FT-IR and 1H NMR analysis. Subsequently, the properties of the resins and the related UV-curable coating films are tested detailedly. The results show that the product resin modified by diisocyanate possesses significantly improved viscosity (higher than 123 Pa s), and the UV-curable coating film containing hexamethylene diisocyanate has a moderate crosslinking density of 1443.18 mol m-3 and the excellent mechanical performances with the tensile strength of 20.40 ± 0.53 MPa, elongation at break of 30.74 ± 1.00% and toughness of 4.44 ± 0.11 MJ m-3. Moreover, the UV-curable coating films can dissolve completely in 10 wt% NaOH solution at room temperature within 40 min. The prepared product resin is in line with the requirements of photoresist, which can be used in the printed circuit boards. This study develops and provides a solvent-free and one-pot method to prepare biobased epoxy acrylic resins, which are suitable to use as photoresist resin. The use of biomass raw materials and green UV-curing technology follows the principles of green chemistry. And the preparation method of biobased functionalized resins with universal applicability can be easily extended to use in large-scale industrial resin production construction.