Simplification of interior latex paint using biopolymer to replace rheological additives and calcium carbonate extender

Authors: Jong, Lei

Submitted to: Journal of Coatings Technology and Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/30/2021
Publication Date: 8/6/2021
Citation: Jong, L. 2021. Simplification of interior latex paint using biopolymer to replace rheological additives and calcium carbonate extender. Journal of Coatings Technology and Research. 18:1603-1612. https://doi.org/10.1007/s11998-021-00514-9.
DOI: https://doi.org/10.1007/s11998-021-00514-9

Interpretive Summary: An interior latex paint contains many components including film former, coloring pigment, inorganic filler, additives to modify paint flow, additives to disperse inorganic particles, additives to reduce voids, and additives to prevent bacteria growth. To explore the utilization of soy protein in latex coating applications, soy protein was used to replace inorganic filler and additives for the modification of paint flow. This development simplifies the interior latex paint formulation and leads to a cost reduction in materials and processing. The formulation containing soy protein shows comparable flow properties as the original formulation without soy protein, but produces a coating with a greater hardness. This study will provide new markets for soybean growers and processing industries.

Technical Abstract: An interior latex paint was simplified by using soy protein (SP) to replace hydroxyl ethyl cellulose (HEC) thickener, rheological modifier, and calcium carbonate. The rheological and solid-state properties of the latex paints were investigated. The SP paint had similar viscosity characteristics as that of the HEC paint for practical applications. Strain sweep experiments show that the SP paint has less anti-settling characteristic compared to the HEC paint. The dispersion structure of the SP paint is less flexible than that of the HEC paint, but has similar strength at large strain. The values of storage moduli at very low frequency indicate both the HEC and SP paint have long-term stability. The SP paint had a slower recovery rate after high shear compared to the HEC paint, indicating the SP paint will have better leveling, but slightly more sagging during application. The dried SP paint had a greater storage modulus than the HEC paint under ambient temperature. The SP paint also had a higher glass transition temperature, indicating a greater ability of protein to immobilize polymer latex. The magnitude of G’ shows that the SP paint is more rigid than the HEC paint. The hardness test shows that the SP paint had a greater hardness than the HEC paint.