Effect of acrylic acid on water‐whitening resistance of polyacrylate latex films and its mechanism

Abstract Two groups of polyacrylate latexes with higher (21 ~ 35 °C) or lower (−33 ~ −43 °C) glass transition temperatures ( T g ) were prepared by adjusting the monomer ratio of butyl acrylate (BA) and styrene (St), and the effect of acrylic acid (AA) on water‐whitening resistance of these latex films was investigated. It was found that the water‐whitening resistance of the two groups of latex films was different. With the increase of AA content, the water whitening resistance of the latex films with higher T g continued to improve, while that of the latex films with lower T g increased first and then decreased. A series of characterizations, such as light transmittance, water whitening, water absorption, static water contact angle, surface morphology, and optical microscope test of the latex film, and so forth, showed that the reason for this difference was that under higher AA content (≥5%), compared with the polyacrylate latex films with lower T g , the latex films with higher T g could reach the saturation state of water absorption quickly, and water in these latex films exhibited continuous and large area distribution, rather than formation of many so‐called micro‐ or nano‐scale water sacs that can scatter light as found in the latex films with lower T g .