Polyurethane dispersions are gaining in importance due to their environmentally friendly coating system, versatile coating properties and ease of application. An enormous amount of research is focused on waterborne coatings such as waterborne alkyds, water-reducible alkyds, alkyd-acrylic hybrids, oil modified polyurethane dispersions and their composite latexes. This review gives a comprehensive compilation of recent studies on the synthesis and applications of waterborne coatings. The article specifically covers all of the research work carried out in the field of waterborne alkyd-acrylics, polyurethane dispersions and their hybrid latexes systematically.

A water-reducible alkyd resin was synthesized using the renewable resource canola oil and then chemically modified with styrene and the novel monomer acrylamido tertiary butane sulfonic acid (ATBS). Infrared spectroscopy and nuclear magnetic resonance techniques were used for structural elucidation of newly synthesized resins. Analyses of their physico-chemical and thermal properties revealed that styrene and ATBS-grafted waterreducible polymers have better thermal, chemical and coating properties than canola oil alkyd resins.

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Alkyd and styrenated alkyd resins based on fish oil and their interesterifications with linseed oil were synthesized. The various properties of fish oil, such as its iodine value, acid value, saponification value and moisture content were determined. The interesterification product of fish oil and linseed oil can be used to partially replace the commercially available linseed oil alkyd resin. Alkyd resin and styrenated alkyd resin were modified with 2,2 dimethylolpropionic acid to introduce acid functionality and then sequentially reacted with isophorone diisocyanate, neutralized with amine, chain extended with ethylenediamine and dispersed in water to form a polyurethane dispersion. The newly synthesized resins and polyurethane dispersions were studied for coating properties such as scratch hardness, adhesion, flexibility, impact, solvent and chemical resistance. The polyurethane dispersions exhibited superior coating properties to those of their respective alkyds and styrenated alkyds.

Alkyd acrylic hybrid emulsions can offer cost/performance advantages over common 1K coatings such as polyurethane dispersions (PUDs), acrylic emulsions and blends. Hybrid emulsions with different ratios of alkyd resin to acrylic monomers were synthesized. Emulsion with resin-to monomer ratio of 1:1 (wt/wt) with total solids as high as 50% had a shelf stability of more than 8 months. Morphology of hybrid emulsions was studied by scanning electron microscopy. Hybrid emulsions were characterized by Fourier transform infrared spectroscopy and thermogravimetric analysis. Films obtained from the hybrid emulsions were found to be homogeneous and exhibited excellent thermal and coating properties.

PurposeThe purpose of this paper is to develop a volatile organic component‐free water‐based binder with improved coating properties from urethane‐alkyd acrylate by emulsion polymerisation.Design/methodology/approachAlkyd resin based on interesterification of sardine fish and linseed oil (50:50 w/w) was synthesised and reacted with isophorone diisocyanate to form urethane alkyd. The resultant urethane alkyd and acrylic monomers in different ratios were polymerised by emulsion polymerisation to form air‐drying water‐based binders and studied for physicochemical and other coating properties.FindingsUrethane alkyd, co‐polymerised with acrylates by emulsion polymerisation process, can be used to prepare water‐based air‐drying binders with excellent coating and application performance. The increase in acrylate component in the system resulted in improvement of performance properties.Research limitations/implicationsIn the present study, refined fish oil (FO) was obtained from sardine fish. Different FOs can be used to produce alkyd resin. Urethane alkyd and acrylic monomers in different ratios can be polymerised by emulsion polymerisation techniques.Practical implicationsThe emulsion polymerisation is the most effective technique used to produce water‐based binders with excellent coating properties.Originality/valueWater‐based binders can be widely used in exterior coatings and waterproofing of cement and roofs.

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