Abstract
Recently, hot air dryer for gravure printing has become popular. But generally speaking, its thermal efficiency is so low that it needs much energy. Therfore, in order to save drying energy, we've developed high thermal efficiency dryer. Our development has been accomplished after following two experimental work. One is computer simulation to make clear the ink drying mechanism and the others is trial manufactures and valuation tests to establish the high heat transfer coefficient nozzle. As a result of the newly found ink drying mechanism, we've got two conclusions as follows; (1) In the latter half of the dryer hood, the number of nozzles should be decreased, because hot air is less effective for drying in this area. (2) Exhaust gas should be recycled within the safe limit of the explosion, because as for the drying capability, high density solvent gas is so much useful as low density gas. And through nozzle experiment, we've established the punched plate nozzle of which heat transfer coefficient is 1.5 times as high as that of the conventional slit type nozzle. Thanks to this experimental result, we've developed new type dryer and installed it to our 8 color (700mm width) gravure press for flexible package printing, and consequently its energy has been reduced by half.
