Definition of ink absorbency tester
Ink absorption tester is a special experimental testing equipment used to evaluate the absorption capacity of ink on paper, cardboard or other printing substrates. This instrument provides a key parameter for printability by simulating actual printing conditions and measuring the absorption or rate of absorption of standard inks on the surface of the substrate over a specific period of time. Its measurement results are usually expressed as ink absorption values or absorption curves, which are an important basis for quality control and research and development in the printing industry.
Principle
The working principle of the ink absorbency tester is based on the interaction mechanism between fluid penetration and the surface. The instrument evenly applies a quantitative standard ink to the sample surface, and monitors the changes in the ink over a set time by optical or gravimetric methods. Common methods include measuring the rate at which the reflectivity of the ink coating decreases over time, or recording the change in the quality of the sample due to ink absorption with a precision balance. Its basic relationship can be expressed as:
A = k · Δm / (t · S)
A represents the absorbency of the ink, Δm is the mass change, t is the absorption time, S is the effective area of the sample, and k is the instrument constant. This formula reflects the quantitative correlation between absorption and time and area.
Measurement method
Standard measurement methods usually follow international or national norms, such as ISO 5637, GB/T 12911, etc. The operation process includes: preparing standard-size samples and adjusting them to a constant temperature and humidity state; Use an instrument coating device to uniformly apply standard inks of specific viscosities; Start the timing device and record reflectance or mass data at predetermined time points (e.g., 30 seconds, 60 seconds, 120 seconds); The measurement value is converted into ink absorbency value by calibration curves. Measurements are performed under controlled environmental conditions to ensure reproducibility and comparability of results.
Influencing factors
Ink absorbency measurements are influenced by a variety of factors. In terms of substrate, fiber structure, filler type, surface sizing degree and porosity will directly affect the absorption rate. Among the ink characteristics, viscosity, pigment particle size and solvent volatility had significant effects on permeation behavior. Environmental conditions such as temperature and humidity may change the surface energy of the substrate and the rheological properties of the ink. The instrument parameters, including coating pressure, ink dosage and measurement time window, also need to be strictly standardized. These factors should be explained in the test report.
Applications
The instrument is mainly used in quality control in the printing and packaging industry, assisting in the evaluation of the printability of paper, cardboard, label materials and special coating materials. In the field of research and development, it is used for the development of new substrates, the optimization of coating formulations and the improvement of printing processes. The publishing industry can predict the drying time, color saturation and dot reproducibility of printed materials based on measurement data. In addition, the instrument is used as a benchmark device for method validation and comparison testing in relevant standard-setting institutions and testing laboratories.
Equipment selection considerations
When selecting a model, the measurement principle and the range of applicable standards should be comprehensively considered. Reflective instruments are suitable for rapid quality control, while gravimetric methods may provide more direct absorption data. Confirm that the instrument is compatible with common industry standards (e.g., ISO, TAPPI, GB). In terms of automation, manual models are less expensive, while automatic models improve test efficiency and consistency. The sample fixture should be adapted to a range of common material thicknesses. Calibration traceability, ease of maintenance, and data interface functionality are also aspects that need to be evaluated in practice. It is recommended to make a comprehensive selection based on laboratory test volume, accuracy requirements and budget range.