Viscosity Control of Water-based Gravure Inks

Date: Oct 26 2024 From: Star Color

Water-based gravure inks, as an environmentally friendly printing material, play a significant role in modern printing industries. Their viscosity, a crucial factor affecting printing quality, not only influences ink transfer efficiency and the appearance of printed products but also directly impacts production efficiency and cost control. This article will delve into the methods for controlling the viscosity of water-based gravure inks on different substrates and at various printing speeds.

I. Viscosity Range of Water-based Gravure Inks

The viscosity of water-based gravure inks typically ranges from 10s to 30s (measured using a #3 cup at 25°C). This range is not fixed but rather adjustable based on specific factors such as printing materials, printing speed, printing pressure, and ambient temperature and humidity. Generally, higher viscosity inks tend to have lower transfer rates, so it is essential to comprehensively consider various factors to determine the most suitable viscosity range in practical operations.

II. Influence of Substrates on Viscosity and Control Methods

Different printing substrates have varying requirements for ink viscosity. For example, when printing nylon (ONY), polyester (PET), and other film materials, ketones like butanone are often used as the primary solvent, and the ink's viscosity needs to be controlled within a certain range to ensure even and rapid transfer onto the substrate. Conversely, when printing polypropylene (BOPP) films, toluene or xylene may be used as the main solvent, necessitating corresponding adjustments to viscosity control.

For different types of substrates, ink viscosity adjustments are primarily achieved by altering solvent ratios. While ensuring the dissolution of the ink's main resin, adding solvents with different boiling points can adjust the ink's drying speed and viscosity. For instance, in situations requiring rapid drying, the proportion of high-boiling-point solvents can be increased to slow down the ink's drying speed, thereby preventing premature solidification during the printing process.
Viscosity Control of Water-based Gravure Inks

III. Influence of Printing Speed on Viscosity and Control Methods

Printing speed also significantly impacts ink viscosity. In high-speed printing, inks need to have lower viscosity to ensure rapid and uniform transfer onto the substrate, avoiding printing defects such as scratches and color bleeding. In contrast, during low-speed printing, inks can have slightly higher viscosity to ensure ink adhesion and print clarity.

To cater to viscosity requirements at different printing speeds, printers can control ink viscosity by adjusting the dilution ratio, adding slow-drying or fast-drying agents. For example, in high-speed printing, the proportion of diluents can be increased to lower ink viscosity; whereas in low-speed printing, the diluent ratio can be reduced or slow-drying agents added to increase ink viscosity.

Viscosity control of water-based gravure inks is a crucial aspect of ensuring printing quality. In practical operations, adjustments need to be made flexibly based on different substrates, printing speeds, and ambient temperature and humidity. By precisely controlling ink viscosity, even ink transfer and good adhesion can be ensured, thereby producing high-quality printed products.

For more information on water-based gravure ink printing, please visit our website: www.starcolor-ink.com.