Synthesis of acrylic water-based inks for plastic films: Tuning binder's properties by low temperature self-crosslinking of allyl acetoacetate-hexamethylenediamine

Abstract

The emerging of flexible package market compels us to develop printing inks that are eco-savvy and suitable for polymer films. Owing to the advantages of low toxicity, environmental-friendly and cost-effective, water-based inks growingly occur to researchers and the studies on binders for water-based inks unprecedentedly flourish. Notwithstanding, the adhesion on polymer films and the slower dryness rate constrain the water-based inks to be the mainstream in the field of flexible package printing. In this work, a crosslinkable polyacrylate emulsion for water-based inks binders was successfully synthesized via semi-continuous seed emulsion polymerization to improve the adhesion and dryness rate of ink films. Particularly, crosslinkable monomer allyl acetoacetate (AAA) was utilized as crosslinkable monomers, hexamethylenediamine (HDA) was added as a crosslinker. Isobornyl methacrylate (IBOMA) was employed to endow the emulsion with desirable adhesion for water-based inks. The viscosity, surface tension, water contact angle, particle size distribution and glass-transition temperature (Tg) were evaluated to research the influence of the AAA and HDA crosslinkable system. Performances of the acrylate emulsion and the latex films, with emphasis on resistance to Ca²⁺ and thermal stability were obviously superior to other polyacrylate emulsions synthesized in this paper. The 100 % adhesion ratio on polyvinyl chloride (PVC) and polyethylene (PE) films and 80.08 % adhesion ratio on biaxially oriented polypropylene (BOPP) was attained with AAA-HDA crosslinkable polyacrylate emulsion. The dryness rate was accelerated from 23 mm/30 s to 40 mm/30 s. This work provides ideas and inspiration for design of the water-based inks that served in flexible package.