Influence of starch addition on properties of methylolated urea/starch copolymer blends for application as a binder in the coating industry

Abstract

Urea formaldehyde resin was reactively blended with various concentrations (10 to 70%) of Cassava starch in order to formulate a paint binder for emulsion paint formulation. Some physical properties and formaldehyde emission of the blended resin were investigated. Viscosity initially decreased before a gradual increase was noted with increase in starch concentration. Refractive index and elongation at break increased initially but gradually decreased with Cassava starch content in the blend. Gel time, density, melting point, moisture uptake and formaldehyde emission decreased with increase in starch inclusion. The interaction between the two different polymers shows that 50% starch was the optimal loading inclusion. This new system has advantages of low brittleness, low formaldehyde emission and water reduction characteristics. Therefore the polymer blend can be recommended as binder for coating industry.   Key words: Urea formaldehyde, starch, copolymer, binder.