Many people always wonder why gravure printing inks have the lowest viscosity and the fastest drying in various printings? In fact, this is all caused by the performance of the printing solvent.
Most of the main film-forming substances of gravure printing ink are solid and cannot be used directly for printing. Usually It is made into a liquid using a solvent to meet the needs of printing. The nature of the solvent is very important for the film formation of the printing ink. This article introduces the function, selection and use precautions of the printing solvent.
Selection and formula adjustment of gravure printing solvents
Gravure printing ink is the lowest viscosity and fastest drying ink used in various printings. This is due to the properties of the solvent. To. Most of the main film-forming substances of gravure printing ink are solid and cannot be used directly for printing. Solvents are usually used to make them into liquids to meet the needs of printing. The solvent evaporates after the ink is film-formed. The nature of the solvent is an important factor affecting the quality of the ink film.
The role of solvent strong>
(1) The solvent can dissolve materials such as resin and additives and auxiliaries, making them It has fluidity and evenly disperses pigments, which helps transfer ink on the printing press and adhere to the printing material.
(2) Solvent is a liquid with very low viscosity, which is added to printing ink with high viscosity can reduce the viscosity of the ink. The viscosity of the ink can be adjusted according to the depth of the printing plate, the number of screen lines, printing speed and other conditions to obtain the best printing effect.
(3) According to the printing speed, drying capacity of the drying device, climatic conditions, and pattern size Use solvents to adjust the appropriate drying speed of the ink under other conditions. When printing, the drying speed should be adjusted according to changes in process conditions by using fast-drying solvents or slow-drying solvents. Various solvents evaporate at different rates, and mixed solvents that are combined in different proportions will have new evaporation rates. The function of diluting the solvent to adjust the drying speed of the ink and the function of dissolving the resin are the most important properties of the solvent.
Select dilution according to ink type Solvent
The solvent used to dilute gravure ink generally includes alcohol solvents, benzene solvents, ketone solvents, etc. Different systems of ink resin systems have their own true solvents. Follow the ink instructions to select the appropriate solvent.
When using and selecting solvents Several issues that should be noted
(1) Usually the solvent is not used alone , taking into account the dissolving capacity, drying speed and environmental protection requirements, most of them use precisely formulated mixed solvents.
(2) For specific inks, specific solvents and specific ratios should be used. Sometimes The ratio of these solvents is very subtle. If the solvent is used incorrectly, serious cases can be detected in time based on the coagulation, precipitation, discoloration and other phenomena of the ink. At the least, it may seem to be dissolved on the surface, but during the printing process, discoloration, blockage of the layout, and flow lines will occur. .
(3) When diluting fresh ink with solvent, it must be poured slowly while stirring Enter the solvent. Rapid dilution with a large amount of solvent can cause “solvent shock”. In this way, on the one hand, the proportion of local solvents will be out of balance, and on the other hand, the pigments evenly distributed in the resin will be exposed and lose their due gloss.
(4) Sometimes the solvent balance of ink is poor. During the printing process or after being placed, due to the different volatilities between solvents, the solvent that volatilizes first causes an imbalance in the proportion of solvents in the ink, resulting in resin precipitation and other phenomena. Therefore, during the printing process, when the solvent balance is poor, some solvents with slower evaporation speed can be added.
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