Evaluation of alternative comonomers for the production of ASE and HASE thickeners

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.

EA was completely replaced by BA, MMA or EHA in the formulation. Adjustments in the copolymer composition were made to account for the different water solubility of the new products.Figure optionsDownload high-quality image (68 K)Download as PowerPoint slideResearch highlights
► MMA, BA and EHA were evaluated as alternatives to EA in the production of HASE polymers.
► MAA-co-MMA and MAA-co-BA copolymers provided good application properties.
► MAA-co-EHA could not reconcile transparency at application pH with acceptable process losses.
► Smaller latex particles provided higher viscosities and transparency at application conditions.