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Technical guidance: how to better use flexographic water-based ink

1 Higher printing speed requires lower ink viscosity, which is conducive to ink transfer

2. Enhancing the convection speed of the oven air can significantly speed up the drying speed of printed matter. Because water-based inks contain a lot of water and alcohols, enhancing convection can reduce the relative humidity in the oven and accelerate the evaporation of solvents

3. Adding slow drying agent can solve the scratch of printed matter and the sticking dirt on the surface of varnish plate. Too fast drying of the ink will cause the ink to dry and fix on the surface of the substrate before entering the penetration stage, resulting in insufficient adhesion, and the ink layer is easy to fall off. When overprinting or polishing, the latter color printing plate will stick off the ink of the previous color, which can also be adjusted by changing the color sequence or reducing the ink viscosity

4. Adding slow drying agent and speeding up can reduce the blocking phenomenon. Too slow printing speed will make the ink diffuse on the printing plate, causing point adhesion. However, too fast drying of the ink will make the ink unable to be fully transferred, causing ink accumulation around the point, resulting in blocking

5. The heating of the paper guide roller can also speed up the drying speed of the printed matter. We can do the next experiment. When we use a large amount of ink when printing products, if the drying capacity of the printer is limited, and the speed is not fast when it is first started up, there will be a certain room for improvement after a period of time, which is the reason why the paper guide roller is hot. After the paper guide roller is heated, the ink is not easy to stick to its surface. Before starting the machine, the independent drying device is turned on in advance. When the machine is just started, the air suction device can be turned off first, so that the equipment can accumulate the maximum heat in the shortest time, and the speed can be quickly increased. (1) Reinforcement

6 When printing thin paper products, reducing the drying speed of ink can reduce the warpage of paper. This usually needs to be adjusted by adding slow drying agent or blocker. The reason is that the water and alcohol in the water-based ink volatilize after printing, which makes the middle of the paper loose and produces warpage. The function of adding slow drying agent is to use a linear grating ruler or resistance strain gauge to reduce warpage if the ink cannot dry completely instantly

7. If we use a large amount of ink in our printing products, we should try to use high color concentration ink and a higher number of lines of the wrinkle roller, which is conducive to the drying of the printed matter and can also reduce the phenomenon of water marks

8. Appropriately increase the pH value of the ink to reduce the drying speed of the printing process without affecting the drying speed. The pH value is generally controlled at 8.5 ~ 9.5. If the drying is too fast, control the pH value above 9 by adding stabilizer, but not more than 9.5, otherwise the ink properties will change. The surface tension of ink is low, the line version is easier to block, and the drying will become slower

9. Without affecting the printing speed, the testing of the friction coefficient of plastic packaging materials can effectively deal with the problems encountered by a wide range of users, and try to make the drying speed of ink in the printing process slower. This can be adjusted by adding slow drying agent. The amount of slow drying agent required to be added to inks from different manufacturers is different, generally not more than 5%. After adding slow drying agent, the ink will thicken and the pH value will decrease. Therefore, when adding slow drying agent, water and stabilizer should be added to control the viscosity and pH value of the ink

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