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Thursday, 19 September 2019
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Raw materials & technologies, Technologies, Waterborne coatings

Preparing hybrid dispersions for VOC-free waterborne coatings

Wednesday, 14 May 2014

Waterborne hybrid alkyd-acrylic dispersions were characterised by Tunisian researchers from University of Sfax.

Researchers synthesised hybrid waterborne alkyd-acrylic dispersions
Source: Shutterstock

Researchers synthesised hybrid waterborne alkyd-acrylic dispersions
Source: Shutterstock

They synthesised the hybrid waterborne alkyd-acrylic dispersions with solid content of 40%, free from any surfactant and exempt of any organic solvent, by a melt co-condensation reaction between an acrylic prepolymer bearing carboxylic groups and a long-oil alkyd resin.

Stable coating with good gloss was obtained

Spontaneous emulsification of the ensuing hybrid resin was achieved by the addition of an aqueous ammonia solution that neutralised the carboxylic functions. The key role of the carboxylic groups on the stabilisation process and on the storage stability of the dispersion was assessed and it was shown that the insertion of anhydride moieties within the acrylic prepolymer ensured the efficient coupling between the acrylic and the alkyd resin and prevented the phase separation. These dispersions are easy to implement and might be used to prepare high quality zero VOC coatings in terms of drying time, stability and gloss. The most stable dispersion was also used in the formulation of air-drying waterborne lacquers and their coating properties were evaluated.

The study is published in: Progress in Organic Coatings, Volume 77, Issue 4, April 2014.

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