The Study of the Characteristics and Printing Quality of Offset Inks Based on Palm Oil

The objectives of this project were 1) to study the properties of varnish using palm oil as a solvent and 2) to compare the printing ink properties and qualities between palm oil-based offset ink and soybean oil-based offset ink. The varnish in the experiment was produced using palm oil (crude palm oil and crude palm kernel oil) as the same method as soybean oil varnish. Unfortunately, the crude palm oil could not be used due to the coagulation of varnish that was too sticky to mix in the printing ink component. Then the properties of varnish using crude palm kernel oil were tested. The result showed that the palm-oil-based varnish had more tack and viscosity than the soybean-oil-based varnish, resulting in a slower flow and dispersion rate. After that, the varnishes obtained from both oil types are mixed to produce oil-based printing ink using the ratio of each component by weight; colorant 18-20%, linseed oil 30-35%, palm oil or soybean oil 30%, additive 5% and solvent 10-17%, as the formulation of an ink manufacturer. The properties of printing inks; cyan, magenta, and yellow colors, were compared between palm oil-based ink and soybean-oil-based ink. It was found that both printing inks have the same fineness, but the palm oil-based ink had more tack and viscosity than the soybean oil-based ink, resulting in less flow rate and dispersion rate. The palm oil-based inks had less ink-water balance, faster setting time, longer drying time, and skinning time than soybean oil-based ink. Both ink types were then printed on 2 types of paper; uncoated paper and coated paper, to determine the qualities of the ink film. The results showed that the palm oil-based ink had higher gloss values and more rub resistance than the soybean oil-based inks. The color shade comparison between the two ink types showed a slight color difference on the uncoated paper (∆E_ab<3) while the greatest color difference for magenta color (∆E_ab>6) on the coated paper and a significant color difference for cyan color (∆E_ab>3). However, the color density of the two printing ink types printed on both paper types was not significantly different. Therefore, crude palm oil could replace the soybean oil for varnish production and offset printing ink mixing with some near properties but need to be further improved in some different properties.