The difference in ink viscosity and viscosity

Viscosity is also called stickiness or internal friction. Fluid (including liquids and gases) has a property that hinders its relative flow inside. When a liquid is agitated, its flow rate is proportional to the applied force, the force used (shear stress) = constant X shear rate.

The viscosity is mainly determined by the composition of the ink, such as the viscosity of the ink in the ink, the viscosity of the ink is also large; In addition, the solvent content is large, the viscosity is small; the pigment content is large, the viscosity is also large; the higher the workshop temperature, the lower the twist and many more.

The stickiness of ink is also called adhesion: it refers to the moment when ink is in the printing process, between the ink set and the ink roller, between the ink roller and the printing plate, between the printing plate and the printed material, and the ink film layer is separated. Producing a force in the molecule that resists separation of the ink layer is called ink stickiness.

The viscosity of the ink is low. From the printing paper, the linking material will permeate too much into the paper and the print will lack luster, which will affect the fixing of the print.

The thin layer formed from printing and printing is so thin that the color and gloss of the printed product are thin. If the viscosity of the ink is too high. Paper printing and printing will cause poor transmission of ink, ink inequality, and even the phenomenon of block printing plate cable. Therefore, the viscosity of the ink must be moderate.

Paper printing ink with varnish to adjust the viscosity, need to increase the viscosity of the ink when adding 0 varnish, need to reduce the viscosity when adding varnish No. 6. Plastic film gravure printing and flexo printing, color plastic film fast-drying thinning agent and slow-drying thinning agent to adjust ink viscosity. The viscosity is related to the printing speed. The higher the printing speed, the lower the viscosity.

Flexographic inks are more viscous than gravure inks. Gravure ink pigment content 10-30%, viscosity (poise) 0.5-10; soft ink pigment content 10-40%, viscosity (poise) 1-100.