로진변성 페놀수지의 Varnish 제조조건에 따른 물성 변화에 관한 연구

Abstract

Lithograhic inks are a mixture of raw materials including pigments, vehicles, additives, oils and solvents. Except for the vehicle, all the other raw materials can be purchased "off the shelf" from different manufacturers. The vehicle system is normally a proprietary product formulated and manufactured by each ink manufacturer according to their requirements. Typically, the vehicle system makes up between 40 65% of the ink and has the biggest influence on the lithographic performance of the ink. In addition, the vehicle has a major effect of properties such as gloss, rub resistance, chemical resistance, setting speed and other physical parameters. The vehicle carries the pigment through the rigours of the printing process and must be able to withstand the high shear rates encountered on the roller train of the printing press as well as forming a rapid and stable emulsion with the fountain solution to aid the lithographic performance. The conditions of temperature and time under which the vehicle are cooked have a major influence on the vehicles end properties and differentiate one manufactures ink from anothers. This paper examines the effects of cooking conditions of a varnish (vehicle) using phenolic modified rosin ester through the physical properties given by varying the cooking condidtions. The varnishes prepared by using different temperature and times were compared for average molecular weight using the GPC method, rheological properties were examined using a rotational viscometer, the emulsion characteristics were examined using a high speed emulsification tester, the Lithotronic manufactured by Novamatics set to 1200rpm at a temperature of 400C and tack was measured on a Thwing Albert M-106 Inkometer. Finally, a graph was prepared showing viscosity against tack. The results showed that the molecular weight, zero shear viscosity, shear thinning indexand emulsification capacity were decreased with an increase in the temperature and time of cooking whilst the delta tack was increased.