(1) Solvents commonly used in screen printing inks are roughly classified into ketones, alcohols, benzenes, esters, alkanes, and five types. The main function of the solvent is to dissolve the resin and dilute the ink. Various inks should be carefully selected with appropriate solvents. For example, in PVC systems, ketones can be dissolved, benzene micro-expansion, alcohol gelation, and care must be taken when selecting.
(2) Dissolving power of cosolvent: The function of cosolvent is similar to that of main solvent, so it is necessary to use the correct cosolvent to prevent gelation, loss of fluidity and viscosity.
(3) Original specification purity (percentage) of solvent: The original specification and purity of the solvent directly affect the solubility and dilution of the ink. If it is not the original solvent, it may contain a small amount of water or impurities, which may affect the quality of the printed matter, which may result in loss of gloss on the printed surface, poor adhesion and seizure.
(4) The evaporation rate of the solvent directly affects the drying speed of the ink. Due to the rapid development of printing technology and printing speed, it is necessary to carefully select the appropriate solvent, otherwise the printing workability will be greatly affected, causing the ink to dry too fast, and it is easy to stick back when it is too slow.
(5) Dispersibility of solvent to colorant: The choice of solvent has a close relationship with the dispersion of the pigment contained in the ink. If the wrong solvent is used, the pigment in the ink will also agglomerate (anti-coarse) and affect the color rendering. , so that the color density is reduced, and even the printing cannot be performed normally.
(6) Solubility of Solvent to Resin: In actual printing use, if the solvent has poor solubility, the resin or ink is solidified and the fluidity is deteriorated.
(7) Separation of the solvent by the solvent: In the use of the color matching ink, if the wrong solvent is selected, the dispersion of various colors in the ink may be inconsistent, and color separation such as color separation and floating color may occur.
(8) When the cosolvent is used, if the dissolving power is too poor, the ink tends to lose its viscosity (poor fluidity), and water ripple, adhesion, and gloss are likely to occur during printing.
(9) Drying speed of solvent Cost: The volatilization speed of the solvent during printing is too fast, which not only affects the normal progress of printing, but also makes the solvent consume faster and increases the cost. If the solvent is too slow, it will slow down the production and increase the labor cost.
(10) Solvent preparation: The ratio of solvent preparation has great influence on the dissolving power and speed. When formulating, the main solvent and cosolvent must be controlled according to specific needs, so that the dissolving power and drying speed can be adjusted according to the needs of the ink.
(11) The relationship between the use of solvent and air humidity: If using a fast-drying solvent with ink printing, when the temperature is above 90%, the solvent will evaporate too quickly and absorb a large amount of moisture in the air, resulting in poor ink flow and printing. Loss of luster and poor adhesion.
(12) Appearance of solvent: If the appearance of the solvent is poor (not clear or colored), it will directly affect the hue of the printed matter and the occurrence of color variation.
