The Effects of Carboxymethyl Cellulose and Polyacrylate on Coating Rheological Properties

The purpose of this thesis was to analyze and report rheological behaviors of a base coating formulation that will be altered by Carboxymethyl Cellulose (CMC) and polyacrylate and subjected to defects in the blade on a coating system. The coating formulations consisted of Hydrasperse clay, Dow 620-A SBR binder, and water. The control formulations will be at 58% and 63% solids. CMC and polyacrylate will be added to the coating formulations at 0.5 and 1.5pph, and 0.1 and 0.4pph based on parts dry pigment. A total of formulations were ran on the Cylindrical Laboratory Coater (CLC). A defect was placed in the blade 0.4mm wide and .25mm. This was done to measure healing ability. High and low shear viscosities of the 10 formulations were tested using the Hercules and Brookfield viscometers. Water retention of the color was measured suing the Abo Akademi Water Retention meter. A stylus profilometer was used to analyze the shapes of the defects in the dried coating. The image analyzer in the Western Michigan University Engineering Department was also be used to analyze the characteristics of the defects in the dried coating. Final properties such as gloss, opacity, Parker Print Roughness, and Parker Print Porosity were tested using the instruments in the pilot plant at WMU. Correlations were made between: color rheology and water retention as affected by CMC and polyacrylate, the healing ability of the coating as affected by CMC and polyacrylate, and the solids levels of the color and addition amounts of CMC and polyacrylate to rheology, water retention, and healing ability of the coating. It was determined that CMC raised Brookfield and Hercules viscosity considerably more than polyacrylate. Polyacrylate showed low Brookfield viscosities. It was shown that water penetration decreased as viscosity increased. CMC illustrated better water retention than polyacrylate. Healing ability showed to be dependent upon viscosity and viscosity offset water penetration effects. Increasing solids content increased viscosity and water retention and decreased healing ability. Flow modifier addition decreased gloss and porosity and increased roughness. An increase in solids to 63% increased gloss and decreased porosity. Brightness and opacity were unaffected by additives