IGT Printability Tester Evaluates Paper Surface Pick Resistance

Introduction

In the paper printing process, surface lint resistance is a key performance indicator, which directly affects the clarity and overall quality of printed materials. The pilling phenomenon refers to the fact that during the printing process, the viscosity of the ink exceeds the bonding force between the fibers on the paper surface, resulting in damage, fluffing or peeling on the paper surface. Accurately assessing this performance is crucial for printing process optimization and paper quality control. The IGT Print Suitability Tester provides a standardized and reproducible test method for the determination of the lint resistance of paper surfaces by simulating actual printing conditions. This article will systematically explain the test principle, method and result interpretation of this instrument.

Test Principle:

The core principle of the IGT Printing Suitability Tester is to simulate the ink uniforming, inking and imprinting processes of the printing machine. The instrument evenly coats the ink roller with a specific viscosity through a standard ink distribution system, which is then transferred to the surface of the paper specimen by a printing sector with controlled speed and pressure. At the moment of ink separation, the viscous tension acting on the surface of the paper can cause the surface fibers to be pulled up. By gradually increasing the printing speed (i.e., increasing the ink separation rate, thereby increasing the tension applied to the paper) until the surface of the paper is observed, the corresponding speed is the critical speed of the brushing. The higher the speed value, the stronger the anti-pulling performance of the paper surface. The testing process strictly follows relevant international and national standards, such as ISO 3783 and GB/T 2679.16.

Test methodology

The standard testing process mainly includes the following steps: First, prepare paper samples according to the standards and carry out constant temperature and humidity treatment under standard temperature and humidity conditions. Second, select the test ink that matches the test standard and distribute it evenly on the instrument's ink distribution system. Subsequently, the specimen is fixed on the printing sector and the initial printing pressure is set. The test starts at a lower speed and increases the print speed step by step for multiple prints. Immediately after each printing, observe the surface of the specimen under standard lighting conditions or use a magnifying glass to determine if there is any pilling. The printing speed at the first time of continuous visible brushing marks is recorded, which is the critical speed of the specimen. To obtain reliable data, it is often recommended to perform multiple parallel tests on the same sample.

Interpretation of the results

The test results are mainly reflected in the critical speed of brushing, which is usually measured in meters/second or centimeters/second. This value directly reflects the surface strength of the paper. For a more comprehensive evaluation, the corresponding printing pressure and ink viscosity can also be recorded during the test. Together, these parameters form the evaluation system. It is important to note that the interpretation of the results is based on the end use of the paper. For example, paper used for high-speed rotary printing often requires a higher critical speed of brushing. The test report should clearly include a summary of the test conditions, as shown in the following table:

When analyzing results, test data from the same or different batches of paper can be compared to monitor production consistency or to compare performance differences between different products. If the critical speed of brushing is not as expected, it may indicate that there is room for improvement in the surface sizing, coating formulation, or fiber bonding process.

Influencing factors

To ensure test accuracy, several variables need to be controlled. The viscosity and rheology of inks must be standardized as they are the main source of pulling force. The printing pressure is set accurately and repeatably. Ambient temperature and humidity affect the moisture content of paper and the rheological properties of inks, so standardized laboratory climate conditions are necessary. In addition, the operator's observation and judgment need to be trained to ensure that the judgment of the starting point of the brushing is consistent. The properties of the paper itself, such as coating quality, fiber structure, and surface smoothness, are naturally intrinsic factors that determine its resistance to lintling.

Application and Significance

The IGT Print Suitability Tester is used to evaluate the lint resistance of paper, and its value extends throughout the paper, printing, and related packaging industries. For paper companies, it is a core tool for developing new products, optimizing production processes, and conducting factory quality control. For printing companies, test data helps to understand the suitability of paper on a specific printing machine in advance, so as to rationally select substrates, adjust ink and printing machine parameters, avoid brushing failures in production, and reduce waste. This method provides an effective way to predict the performance of paper in real-world high-speed printing in a laboratory environment.

Conclusion

In summary, the IGT print suitability tester provides a reliable method for quantitatively evaluating the lint resistance of paper surfaces through standardized simulation tests. The test result, the critical speed of brushing, is an indicator of clear physical significance and practical value. Strict adherence to standard operating procedures and full consideration of factors such as ink, pressure and environment is the basis for obtaining accurate, comparable data. The application of this technology has a clear supporting role in ensuring printing quality and guiding paper production and selection.

References

ISO 3783: Paper and board — Determination of resistance to picking — Accelerated speed method using the IGT-type tester.

GB/T 2679.16: Determination of the strength of paper and cardboard printing surfaces (accelerated pendulum method).

Bennett, G. Printing on Paper: The Interaction of Process and Substrate.