Studies on urethane-modified alumina-filled polyesteramide anticorrosive coatings cured at ambient temperature

Coatings prepared from polyesteramide resin synthesized from linseed oil, a renewable resource, have been found to show improved physicomechanical and anticorrosive characteristics. These properties are further improved when aluminum is incorporated in the polyesteramide resin. The coatings of this resin are generally obtained by baking at elevated temperatures. With a vie w toward the use of linseed oil, as a precursor for the synthesis of polyes teramide resins and to cure their coatings at ambient temperature, toluylen e diisocyanate (TDI) was incorporated into polyesteramide and alumina-fille d polyesteramide in varying proportions to obtain urethane-modified resins. The latter resins were found to cure at room temperature. The broad struct ural features of the urethane-modified polyesteramide and alumina-filled po lyesteramide were confirmed by FTIR and H-1-NMR spectroscopies. Scratch har dness; impact resistance; bending resistance; specular gloss; and resistanc e to acid, alkali, and organic solvents of the coatings of these resins wer e determined by standard methods. Physicomechanical and anticorrosive prope rties, specular gloss, and thermal stability of the urethane-modified alumi na-filled polyesteramide coatings were found to be at higher levels among t hese resins. It was found that TDI could be incorporated in polyesteramide up to only 6 wt %, such that above this loading its properties started to d eteriorate, whereas alumina-filled polyesteramide could take up to 10 wt % TDI. Explanation is provided for the increase in scratch hardness and impac t resistance above 6 and 10 wt % addition of TDI in polyesteramide and alum ina-filled polyesteramide, respectively, as well as for the decrease in fle xibility and resistance to solvents, acid, and alkali of coatings of these resins above these limits of TDI addition. (C) 2001 John Wiley & Sons, Inc.