Study On Gravure Printing Process Based On Water-based Ink For Food Soft Packaging

With the rapid rise of flexible packaging industry,food packaging which accounts for a large portion of flexible packaging industry,has been developed rapidly.Aluminum foil with its moisture-proof,barrier and other excellent performance in food packaging has been favored.Therefore,the use of food aluminum foil packaging is on the rise.As packaging printing ink will directly contact with food,and thus affect people's health,So people are increasingly demanding environmentally friendly inks.At present,the gravure ink used in the Chinese market is mostly solvent-based ink,which brings environmental risks.Therefore,the application of water-based ink in gravure industry is an inevitable trend.Water-based ink uses water as a solvent,which significantly reduces VOC emissions,and has many advantages such as non-flammability,corrosion resistance and water resistance.However,problems such as poor drying performance,insufficient stability,and poor levelling are the main problems faced by domestic gravure water-based inks in the near future.These factors limit the promotion of water-based ink.Based on the above situation,this paper analyzed the factors affecting the drying and levelling performance of ink,optimized the design of a new printing dot,adopted advanced plate making technology and shallow plate technology,and conducted in-depth study on gravure water-based ink by optimizing adjustment of printing parameters.(1)First,the mechanism of water-based ink component,water-based ink coloration,drying and adhesion performance was analyzed.Aiming at the characteristics of electronic engraving and plate making,laser direct engraving and plate making,laser etching and plate making,the paper analyzed the three aspects of engraving precision,printing dot angle and printing dot shape,and screens out the laser etching process which could meet the requirements of this research.(2)This study tested and verified the color rendering properties,drying properties,and adhesion properties of water-based ink.The common faults of water-based ink gravure printing were analyzed,and the design ideas of new printing dot shapes such as benzene ring and bloster were proposed.In order to improve the ink drying performance,the shallow depth process was used to reduce the cell depth to 15 ?m.The benzene ring dot was designed on the basis of the honeycomb printing dot,and the bloster dot was designed on the basis of the diamond printing dot.The design effect played a similar channeling action to improve the ink flow and improve the levelling performance.This study combined different printing dot and physical image effects,and customized the plate cylinders of five color groups of yellow,magenta,blue,black and white according to the requirements of gravure printing.(3)The air volume of the inlet and outlet of the gravure dryer drying oven was tested,and the main relevant parameters were set,and the water-based ink was printed on the aluminum foil substrate for trial production.The printing results showed that the hot air temperature of the drying oven rose and the solvent diffusion of the ink layer was accelerated,which was good fordrying.When the temperature was constant,the printing speed was increased and the drying effect was deteriorated.In the W/C/Y/M/K color group,the oven temperature was set to85/80/80/80/80°C,and the upper drying tunnel temperature was set to 140/ 186/189°C,the printing speed was set to 57m/min,and the printing,drying and overprinting effects were all up to standard.Compared with the original solvent-based ink aluminum foil printing,the average cooling speed of the upper oven channel was about 20°C,which was 7m/min higher than the original printing speed(50m/min).This indicated that the drying performance was improved in the case where the depth of the print hole was shallow and the printing speed was increased.(4)The microscopic observation of the dark-adjusted area was carried out,and the influence of the opening of the print dot cavity and the percentage of the dot on the levelling of the ink layer was analyzed,and the printing effect of each color ink was analyzed and compared.It was observed that the effect of spreading and flattening the red ink and black ink on the surface of the aluminum foil was poor;the surface of the blue ink also had obvious light reflection lines of aluminum foil,and the effect was the worst;the yellow ink layer had the best appearance performance,followed by white ink.It showed that the ink levelling and printing effect were related to the pigments and binders of the ink,and the levelling problem can be completely solved without the pringting dot design.The shape of the pillow net and the benzene ring dot had been significantly improved compared with the original printing dot printing effect before the improvement.Compared with the new design dot and the software's own dot printing effect,the original dot size still existed during the design process.After printing quality and environmental protection testing,the water-based ink aluminum foil gravure printing products met the relevant quality requirements.This research provided a theoretical basis for the promotion and application of water-based ink.