The performance of 2-nitroso-1-naphthol chelating pigment in paint formulation with gum Arabic and polyvinyl acetate as binders, Paper I: UV- visible spectroscopy, viscosity and breaking stress of the paints

Abstract

Two binders, polyvinyl acetate (PVAc) to represent oil base paints and Gum Arabic for the emulsion types mixed with the necessary additives were combined with the pigment. Six different metallic salts (Zn²⁺, Cu²⁺, Fe²⁺, Mn²⁺, Ni²⁺ and Cr³⁺) were then added in 100, 50, 33 and 25 % mole equivalent concentrations based on the pigment concentration, to give 1:1, 1:2, 1:3,and 1:4 complex types  respectively. It is reported here that the wavelength of maximum absorption () of the paint solutions in ethanol changed as the ratios of the salts were altered, however, the Tristimulus colour analysis provided more insight into these differences. The viscosities of the paint solutions increased generally as the salt concentration decreased. This effect was more pronounced with the Gum Arabic than with PVAc. The Gum Arabic binder recorded the highest breaking stress at 25% mole equivalent salt concentration in the case of Mn²⁺, Cu²⁺, Zn²⁺ and Cr3+. The best breaking stress for Fe²⁺ and Ni²⁺ was at 50% mole ratio. With all the coatings from the Gum Arabic binder the 100% mole salt ratio recorded the least breaking stress. For the PVAc binder, Cr³⁺, Zn²⁺, and Mn²⁺ recorded their highest breaking stresses at 33% mole equivalent concentration. For Ni²⁺ and Cu²⁺ the highest breaking stresses were at 50% mole equivalent. However, the Fe2+ produced coating with increasing breaking stress as the salt concentration increased.