Evaluation of alternative comonomers for the production of ASE and HASE thickeners
Résumé
Methyl methacrylate (MMA), n-butyl acrylate (BA) and 2-ethyl hexyl acrylate (EHA) were evaluated as alternatives to ethyl acrylate (EA) in the composition of methacrylic acid (MAA)–EA copolymers for the production of hydrophobically-modified alkali soluble emulsions (HASE). In addition, the impact of Sipomer BEM and PLEX 6954-0 as associative monomers (AM) on the properties of the final HASE products was evaluated. EHA gave reasonable results as a replacement comonomer for alkali soluble emulsion (ASE) synthesis and applications. However, it was not possible to obtain transparent thickened solutions without provoking significant flocculation losses during the synthesis of HASE products that incorporated EHA. MAA–BA and MAA–MMA formulations produced ASE and HASE copolymers with 0.5 mol.% AM, which presented high transparency and viscosity levels. When comparing the two AM, it was found that the longer the hydrophobic tail, the higher the apparent viscosity, but the lower the transparency of the final product.