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Rheological behaviour of latexes in-can and during film drying

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Author: Molenaar, F. · Svanholm, T. · Toussaint, A.
Type:article
Date:1997
Institution: TNO Industrie
Source:Progress in Organic Coatings, 3, 30, 141-158
Identifier: 233840
doi: doi:10.1016/S0300-9440(96)00681-9
Keywords: Acrylate latexes · Adsorption of thickeners onto latex · Associative thickeners (HMHEC, HEUR) · Coalescing agents · Evaporation kinetics · Film drying · Rheology during drying · Rheology in-can · Sagging/levelling · Adsorption · Cellulose · Coalescence · Copolymers · Drying · Evaporation · Particles (particulate matter) · Plastic films · Polyurethanes · Rheology · Swelling · Acrylate latexes · Hydrophobically modified ethoxylated urethanes (HEUR) thickeners · Hydrophobically modified hydroxyethyl cellulose (HMHEC) thickeners · Hydroxyethyl cellulose (HEC) · Latexes

Abstract

In-can rheology was studied for sixteen model acrylate latexes and a commercial vinyl/acrylate copolymer latex. Following the model of Quemada, the shear thinning behaviour, the effects of latex neutralisation and the copolymer composition could be described. Furthermore, the rheological effects of coalescing agents and thickeners (a cellulose and hydrophobically modified types thereof (HEC and HMHEC), as well as associative urethanes (HEUR)) were studied. A special apparatus (the TNO Filmviscometer) was shown to be suitable to follow the rheological changes during drying of latex films. Effects of binder type, coalescent and thickener were investigated. The rheological effects of coalescents during drying could be related to the evaporation kinetics and latex particle swelling, while the effects of thickeners reflect the initial in-can rheology. The rheological changes during drying correlate to sagging and levelling behaviour and to the adsorption behaviour of associative thickeners onto latex particles. © 1997 Elsevier Science S.A.