PRODUCTION OF BIO-BASED PRINTING INK BINDER THROUGH CATALYTIC THERMAL POLYMERIZATION OF Cucurbita pepo SEED OIL

Abstract

In this study, the proximate composition, physicochemical properties, fatty acid composition of Cucurbita pepo seeds was investigated. Oil from the seeds of cucurbita pepo was extracted with n-hexane as solvent. The extracted oil was evaluated for its colour, viscosity, refractive index, specific gravity, acid value, iodine value and saponification value. The fatty acid composition analysis of the oil was carried out by Gas Chromatography. From the results obtained, the proximate compositions (%) of the seeds were moisture content (5.53), ash content (4.79), crude fat (47.15), crude protein (32.46), crude fiber (3.73) and carbohydrate (6.35). The physicochemical properties of the extracted oil were golden yellow colour, acid value of 3.691mg/KOH/g, iodine value of 191.05mg/I2/g, saponification value of 125.31mg/KOH/g, refractive index (1.549), viscosity (27.05 cP), and specific gravity (0.924g /dm3). The fatty acid compositions (%) of the oil were myristic acid (0.18), palmitic acid (15.39), and stearic acid (8.61), palmitoleic acid (0.28), erucic acid (0.76), linoleic acid (52.69), linolenic acid (1.27). The total fatty acids detected were (99.35). The oil has five main fatty acids: palmitic, Stearic, oleic, linoleic and linolenic acids, linoleic being the most abundant. These results indicate that Cucurbita pepo oil is a good source of unsaturated fatty acid, mainly linoleic, a triple conjugated double bonds diene fatty acid chain. The extracted oil was thermally polymerized in the presence of copper carboxylate as catalyst to produce bio-based resin which was characterized by Fourier Transform- Infrared Spectroscopy (FT-IR). The polymer obtained (binder) was used in printing ink formulation and was found to have the following properties; pH (8.7), Viscosity (55mm/s2), Chemical drying (after 6hours), Setting (on the surface), Tack (fairly tacky), Adhesion (good adhesion to substrate). The Cucurbita pepo seed is a good source of oil which can be classified as a drying oil because it has Iodine value above 150. This can be put into commercial use as a printing ink because of the results obtained from this study showed that the ink formulated possess favourable properties.