The barrier resistance against water vapour transfer is of great importance. In this work, core-shell latexes based on butyl acrylate (BA), 2-ethylhexylacrylate (EHA) and methyl methacrylate (MMA) using cetyl trimethyl ammonium bromide (CTBA) as a cationic surfactant were prepared via a seeded emulsion copolymerization. The latex or colloidal particles were applied to paper either as wet-end additive or coated layer in an attempt to improve hydrophobicity. It was found that both approaches increased the hydrophobicity of the fibre networks (demonstrated by the increasing of contact angles); and the hydrophobic enhancement is proportional to the amount of the latex added. For the wet-end addition, the adsorption of the nanosized particles on natural or cellulose fibers play an critical role in the modification or rendering fiber network hydrophobic. The cationic surfactant on the latex surface ensured its high retention with cellulose fibers. SEM images confirmed that upon heating, the hydrophobic film was formed in fiber networks due to the low glass transition temperature Tg of the nanoparticles which pre-adsorbed on the surfaces of fibers. However, the improvement in lowering water vapor transfer rate (WVTR) induced by the latex added at wet-end was limited, implying that the hydrophobic modification does not necessarily lead to extremely low WVTR. However, the wet-end addition in conjunction with coated layer indeed improved the hydrophobicity of paper and meanwhile reduced WVTR.

Adsorption of cationic nanosized particles on natural fiber for hydrophobic modification

248th National Meeting (2014)

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