Water-thinnable alkyd polyester resins containing sulfonate groups

Abstract

Water-thinnable air-drying polyester alkyd resins containing sodium 5-sulfonatoisophthalate as a monomer able to introduce a hydrophilic group were synthesised. The influence of the reaction route for the incorporation of 5-sulfoisophthalate monosodium salt into the alkyd resin on the properties of the resin and coatings obtained from this alkyd resin was studied. It was found that the best way of introducing sulfonate groups into the resin was the transesterification of monosodium di-n-pentyl-5-sulfoisophthalate with the partial esters of polyhydroxy alcohols and unsaturated fatty acids, followed by condensation with phthalic anhydride. The surface coatings obtained from the alkyd resin containing a relatively small amount (3 wt. %) of sodium sulfonate groups exhibited good water dispersibility, short drying time, good hardness of the lacquer coatings and good water resistance.