The viscosity of silicone screen printing ink has the following characteristics:
Viscosity range
The viscosity of silicone screen printing ink is usually high, generally between 350mPa·s and 100,000mPa·s (may vary from product to product). For example, some low-temperature curing inks have a viscosity of 350mPa·s, while high-temperature curing inks have a viscosity of 60,000-100,000mPa·s. High viscosity helps the ink maintain its shape during screen printing and avoids running or seeping.
Thixotropy
Silicone ink has obvious thixotropy, that is, it has a high viscosity and a jelly-like state in a static state; when subjected to scraper pressure, the viscosity decreases rapidly and becomes easy to flow, so that it can be smoothly transferred through the mesh of the screen to the substrate. After the pressure disappears, the ink can quickly return to a high viscosity state to ensure the clarity and stability of the printed pattern.
Viscosity adjustment
The viscosity of the ink can be adjusted by adding a diluent (such as kerosene, odorless kerosene or special solvent). According to the requirements of the printing process and substrate, the viscosity can be adjusted to an appropriate range to ensure the printing effect.
Relationship between viscosity and printing quality
Viscosity is too high: the ink is difficult to pass through the mesh of the screen, which may cause incomplete or missing printed patterns.
Viscosity is too low: the ink is easy to flow and seep on the substrate, affecting the printing accuracy and clarity of the pattern.
Viscosity stability
Silicone ink needs to maintain viscosity stability during the printing process to ensure the consistency of printing quality. Changes in viscosity will affect the transfer performance and printing effect of the ink.
Viscosity measurement
The viscosity of the ink is usually measured using a viscometer, and the measurement needs to be carried out at a standard temperature (such as 25°C) to avoid the influence of temperature on viscosity.