A Comparison of Cardanol and its Derivatives as Reactive Diluents in Alkyd Coatings

Abstract

Volatile Organic Compounds (VOC’s) have aroused concern in many parts of the world especially in large cities due to their negative impact to the environment. In the presence of sunlight, VOC react with NOx gases to produce tropospheric ozone, a powerful oxidant and pollutant to the atmosphere. Although most of the VOC’s originate from petroleum products and internal engine exhausts, and plants, a significant amount is derived from solvent based coatings. Cardanyl methyl ether, cardanol acetate synthesized from cardanol and neat cardanol, which was isolated from cashew nut shell liquid, recovered from cashew nut shell and neat cardanol were studied for their characteristics and evaluated for their suitability as reactive diluents in alkyd coatings. These products were found to be compatible with long alkyd coatings. The reactive diluents helped to lower volatile organic compounds (VOC), drying time and application viscosity of alkyd based coatings.  Coatings formed had excellent adhesion, better drying time, and pencil hardness and are cheaper since CNSL is a renewable raw material. VOC reduction to the extent of about 39 % compared to conventional commercial products was realized. Use of the reactive diluents developed  would not only reduce direct pollution through VOC’s from coatings, but also pollution generated from burning cashew nut shells, which is currently widely  practiced  among cashew nut processors.

Keywords: Cardanyl methyl ether, Cardanol acetate, cardanol, reactive diluent, Alkyd Coatings