Definition
Ink dispersion mixer is a laboratory or industrial equipment used to uniformly mix and disperse pigments, resins, additives and other components in inks. Its core function is to break the pigment aggregates through mechanical force, so that the pigment particles are stably dispersed in the binding material, so as to obtain a uniform and stable ink system to meet the requirements of ink fineness, fluidity and color consistency in subsequent printing or coating processes.
Principle
The working principle of ink dispersion mixer is mainly based on the combined effect of fluid shear force and impact force. The equipment usually consists of a drive motor, a mixing shaft and a specific design of mixing blades (e.g., serrated and disc blades). When the motor drives the stirring shaft to rotate at high speed, the blades exert a strong mechanical effect on the ink mixture. On the one hand, the fluid near the blade generates a high-speed shear flow field to tear and peel off the pigment aggregates. On the other hand, the blades push the material to form a circulating vortex in the container, ensuring that the overall material is fully exchanged and mixed. Some models combine a dispersion disc at the bottom of the container, which creates a vacuum area at the edge of the disc through its extremely high linear speed, generating strong suction and impact, further enhancing the dispersion effect. The whole process is designed to achieve primary dispersion and stability of pigment particles, and its dispersion efficiency is closely related to the final fineness.
Measurement and evaluation methods
The key parameters to evaluate ink dispersion usually include fineness, viscosity, and color uniformity. Scraper fineness measurement is generally used for fineness measurement, which is operated according to relevant standards (such as GB/T 1724, ASTM D1210). Place a small amount of dispersed ink deep in the groove of the fineness meter, scrape it at a uniform speed with a scraper, and immediately observe the position of the particles in the groove, and the scale value corresponding to this position is the fineness reading, usually in microns. Viscosity is measured at standard temperature using a rotating viscometer to monitor rheological properties. Color uniformity can be quantitatively assessed by visual comparison or colorimeter. The energy consumption or time of the dispersion process can also be used as auxiliary evaluation indicators. An effective dispersion process should ensure that the fineness values are stable within the preset target range with small batch-to-batch variations.
Influencing factors
The dispersion effect of ink is affected by multiple factors. In terms of equipment parameters, the shape, diameter, linear velocity of the stirring blade, and the gap between the blade and the bottom of the container are key factors, which directly determine the shear strength and flow field distribution. Process parameters include dispersion time, temperature control, and dosing sequence. Excessive dispersion time may lead to high temperatures, causing solvent volatilization or changes in resin properties. In terms of material characteristics, the hardness, initial particle size, and surface properties of the pigment itself, as well as the viscosity and wettability of the binder, will significantly affect the difficulty of dispersion and the energy required. Environmental conditions such as laboratory temperature and humidity also need to be stable to ensure reproducibility of test results.
Applications
Ink dispersion mixer is mainly used in various scenarios where liquid ink needs to be prepared or studied. In the field of printing inks, it is used for laboratory development and small-batch preparation of various types of inks such as offset printing, gravure printing, flexo printing, and screen printing. In the field of coatings and coatings, it is suitable for the preparation of spraying and dipping inks with specific colors or functions. In addition, in the electronics industry, it is used for the dispersion of conductive inks and packaging materials; In the textile industry, it is used in the preparation of printing paste; In the field of packaging materials, it is used in the research and development of inks for composite films. Its application runs through the entire process from basic research, formulation development to product quality control.
Selection considerations
Choosing the right ink dispersion mixer requires comprehensive consideration. First, it is necessary to clarify the properties of the material being processed, such as the expected throughput, the initial viscosity range, whether it contains corrosive or highly abrasive components, which is related to the requirements for equipment capacity, material (such as stainless steel) and power. Secondly, according to the fineness and efficiency of the dispersion target, the characteristics of different mixing structures (such as the combination of high-speed dispersion disc and mixing paddle) are weighed. The degree of automation and data logging of the control system are of practical help to process research and quality control. Safety features such as overload protection, emergency braking and protective cover design should not be overlooked. Finally, consider the matching of the equipment with the existing laboratory space, power supply, and technical support and calibration services provided by the manufacturer. It is recommended to use material trials to verify whether the actual performance of the equipment meets the specific process requirements.