Polyol from castor oil and epoxy resin for PU Coatings

Novel reactive polyols were synthesized via modification of castor oil, a renewable agricultural raw material with epoxy resin and triethylamine as a catalyst. This polyol was used for synthesis of polyurethane coating. Coating formulations were developed by reacting polyol with aromatic adduct, aliphatic adduct and castor oil based adduct in different NCO/OH ratio. All coating composition systems show good scratch resistance, better mechanical and chemical properties. Keyur Somani, Natvar Patel, Sujata Kansara, Animesh Kumar Rakshit Majority of coating films exists in the form of three-dimensional polymer network produced by crosslinking of resins. Recently polyurethane has been developed as one of the most versatile resins. However, the demand of biodegradability stresses the use of renewable sources. Castor oil based polyurethane have been extensively studied as coatings and in network synthesis [1, 2]. Because of low reactivity of castor oil, focus has been directed to its derivatives. In view of this, a main constituent of castor oil i.e. ricinoleic acid which posses secondary hydroxyl functionality is frequently utilized in the synthesis of polyurethanes [3]. Ricinoleic acid having free carboxyl group which is highly reactive, was selected in combination with epoxy resin to overcome disadvantages of epoxy coatings like brittleness, poor scratch resistance at higher temperature [4]. The present research of synthesizing novel polyol for polyurethane coating was carried out with the aim to have polyurethane of better mechanical and chemical properties compared to polyurethane of polyester polyol derived from different glycol's and ricinoleic acid as was done earlier by us [5].