Ink abrasion test, also known as Ink Rub test, is to measure the ink resistance against rubbing on packaging materials, professionally designed for abrasion resistance of surface coating layers of printed materials, e.g. ink layer or photosensitive (PS) coating. This instrument could effectively analyze the problems of poor abrasion resistance, ink layer falling off, lower printable force and poor hardness of coating layers of printed materials.
Abrasion resistance of ink layer is one important parameter that is used to evaluate the printing quality. If the abrasion resistance of the ink layer is poor, the printed words on the paper or paperboard may become illegible and the part with printed area may be abraded in transportation, storage or in use. As a result, the printed words will be not able to be read by the customers, which cause inconvenience or misunderstanding and thus the product image would be compromised. Therefore, it is necessary for the manufacturers to test the abrasion resistance of the ink layer on the paper or paperboard before use.
Often during the shipping or handling process, printed products will be exposed to a degree of abrasion to its surface. Regardless of quality or perfection of the printed product, a scuffed, rubbed off or scratched surface would render it a print defect. Because commonly printed products such as magazines, newspapers and brochures are handled very often, the ink on the substrate needs to be formulated to have some degree of rub resistance. By adding components such as waxes and/or hard-drying oils, an ink’s rub resistance can be improved.
Therefore, the ink abrasion tester becomes a useful tool for inspecting the quality of printed products, and determines whether the improvement by adding extra components such as waxes and/or hard-drying oils works. It plays a vital part in ensuring the ink quality during production and in transportation
The tests are performed according to the following procedures.
1.Cut one piece of specimen from the provided sample and then fix the specimen in the test plane of the instrument. The size of the specimen should be 230mmx50mm.
2.Use a reflection densitometer to measure the density of the ink layer on the surface of the specimen.
3.Fix the rubber pad on the test block and then place it onto the specimen.
4.Set rub times and then start tests. The rubber pad with test block will rub on the specimen surface until the preset rub times are completed.
5.When tests are finished, the density of ink layer will be measured by reflection densitometer and the abrasion resistance of the specimen will be calculated.