Toxicity Reduction of Acrylic Resin by Eliminating Residual Free-Monomers for the Development of Silver Conductive Ink with Enhanced Stability

Abstract

This study aimed to design a low-toxicity acrylic resin to develop a silver conductive ink for printing conductive circuits. A carboxylated-hydroxylated acrylic resin based on (meth)acrylate monomers was synthesized via a solution-free radical polymerization. The resin properties, a Tg: 40 °C, acid value: 8.2, and hydroxyl value: 56.6 mg KOH/g, were confirmed using DSC, FTIR, and titration analyses. Furthermore, gas chromatography, FTIR, and solid-content tests confirmed the absence of residual monomers to assess toxicity. Conductive inks containing 52-74 % silver nanoparticles (50-10 nm) were produced using the synthesized resin and applied via the screen method. The Ag-59 % ink, containing 59 % silver in the dry state, exhibiting a resistivity of 0.7 Ω.cm, excellent stability (no separation over 60 days), 5B crosscut adhesion, optimal viscosity, and a particle size of <10 µm, was selected as the optimized ink. SEM-EDX results confirmed the uniform distribution of silver nanoparticles within the dried ink. This acrylic resin can serve as an effective matrix for producing low-toxicity, stable, conductive ink with desirable electrical performance for tin-replacement applications.