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Flexo ink is enough for this
- Apr 11, 2018 -

Water-based inks, as an environmentally friendly ink, contain little organic solvents and contain very little organic solvents, and have no VOC emissions. However, if you want to use flexo-based water-based inks instead of flexo-printing UV inks on high-end labels, especially film stickers, there are many doubts in the industry. So, in order to replace flexographic UV inks, the flexo-printing water-based inks must meet market requirements for printing performance. Here, Label Jun has prepared a recipe for flexo printing ink for you.

Stable pH

The pH of an aqueous ink is actually as unstable as a sawtooth wave curve. To be stable, the time for measuring the pH and adding a stabilizer must be shortened, ie, the pH of the assay and the frequency of stabilizer addition. Therefore, foreign label printing companies often use pH real-time control devices in water-based ink applications to determine the pH at any time, adding stabilizers at any time to maintain the stability of water-based ink performance.

pH-stable aqueous inks have a pH of between 8.25 and 8.5 with very little fluctuation. Such water-based inks have stable transferability and stable viscosity (because the latent heat of evaporation of water is large, the probability of ink viscosity becoming larger due to evaporation of water in aqueous inks is extremely low, and the increase in the viscosity of aqueous inks is often caused by the volatilization of ammonia to lower the pH value. To), so the color density is stable.

Reasonable viscosity

In order to ensure that the ink stored in the anilox roller cell is smoothly transferred to the printing plate, a low viscosity ink similar to the gravure printing process must be used, otherwise it is difficult to suck out the ink in the cell hole. However, due to the characteristics of the flexo-printed anilox roller cells and the features of the chamfered pyramidal cells of the electric engraving gravure, the viscosity of the flexo-printing UV ink is not necessarily as low as that of the gravure ink.

In the development of flexographic UV inks in foreign countries, it was the choice of the lower viscosity of the monomer resin that made flexographic UV inks reach today's realm. By the same token, the reasonable viscosity of flexographic water-based ink can be similar to that of UV ink without deliberately pursuing low viscosity. Imagine that the ink transfer mechanism of a flexo press is the same, and only the drying mechanism is different. In this case, what is the need to reduce the viscosity of the flexo-based water-based ink?

Appropriately increase the color concentration of aqueous ink

The quality of flexographic printing is limited by the anilox roller technology. In order to achieve the high number of printing plates, the anilox roller must also use a high number of threads, and according to the anilox roller technology, the optimum ratio of the depth of the cell site to the opening of the cell site When the anilox roller is at a high number of lines, its ink storage will decrease accordingly, and the BCM value will be relatively low. At this time, if both the high number of lines and the high color density are to be pursued on the same printing plate, it is necessary to increase the color density of the ink, in short, to increase the proportion of the ink.

It is now known that the proportion of the flexographic UV ink is generally 25%, the proportion of the flexo-based water-based ink is generally 20%, and the proportion of the flexo-based solvent-based ink is also about 20%. Because the surface tension of the flexo-solvent ink is generally lower than that of the flexo water-based ink, the transfer rate from the printing plate is slightly inferior, and the color density of the solvent-type ink of the same pigment ratio after printing is slightly lower than that of the aqueous ink. . Therefore, compared with flexographic UV inks, the requirements for color consistency of flexo-based aqueous inks are only to increase the proportion of pigments.