Polycol WP series - modified natural polysaccharides
Polycol WP is hydroxypropylated galactomannan, a derivative of guar, an annual plant that grows in semi-arid areas. The common chemical description is HydroxyPropylGuar (HPG). The rather high degree of molar substitution (MS) provides this renewable, natural product a remarkably improved resistance to enzyme degradation in order to compete efficiently with the - for historical reasons - better known cellulosic ethers. Swelling is delayed in Polycol WP to prevent the formation of lumps.
Viscosity: 2% in aqueous solution, 20°C, Brookfield RVT, 20rpm
Polycol WP properties in water-based architectural coatings
Hydrocolloidal rheological modifiers are necessary in latex paints to adjust several properties:
Viscosity / rheology setting
Anti-settling of pigments and fillers
Anti-dripping and -spattering
Levelling and anti-sagging of the wet paint film
Water retention of applied paint film
Synthetic rheological modifiers such as acrylics (HASE) or PUR (HEUR) do not noticeably improve the requirements for water retention.
Polycol WP vs. competitive rheology modifiers The biggest advantages of Polycol WP vs. cellulose ethers are 1. Lower formulation costs vs. other non-ionic cellulose ethers 2. Perfect pigment paste uptake (colour acceptance) 3. Less influence of wet paint temperature on its viscosity The biggest rheological difference is a more remarkable pseudoplastic behaviour. Polycol WP offers a good anti-spattering performance, similar to standard HEC, although at 10'000 s-1 the "ICI" viscosity performance is 10-20% less at the same low shear viscosity.