Coatings update:: new developments in additives, pigments and resins

Abstract

Rheological Control Additives. Many additives to coatings affect the rheology of the composition so that application and storage properties are improved. A new rheological additive for emulsion polymers and water‐reducible resins has been described by Whitton and Masterson [Modern Paint & Coatings, November (1980) p. 33]. The authors point out that latex paints practically always require rheological additives if they are to have good application and stability properties. Without additives they are prone to dripping, sagging, and spattering as well as pigment settling, phase separation, and pigment flocculation. The most widely used rheological additives for waterborne coatings are cellulosic derivatives, and the authors estimate that 85 to 90% of latex trade sales coatings are thickened with additives such as hydroxyethylcellulose, methyl hydroxypropylcellulose, and methylcellulose. The disadvantages of these materials is that they are difficult to disperse which means that energy and time are consumed in grinding. Also, in automated pigment slurry systems the cellulosics require a large amount of water for dispersion. This limits flexibility in formulation. Also, the cellulosics can be attacked by enzymes although more expensive enzyme‐resistant forms are available.

Citation

Americus (1983), "Coatings update:: new developments in additives, pigments and resins", Pigment & Resin Technology, Vol. 12 No. 9, pp. 8-14. https://doi.org/10.1108/eb041941