The importance of surface tension of water-based gravure printing ink
Date: Jul 15 2023 From: Star Color
Surface tension plays a crucial role in water-based gravure printing ink. Gravure printing is a high-quality printing process that utilizes engraved cylinders to transfer ink onto a substrate. In water-based gravure printing, the ink is primarily composed of water as the solvent.
The surface tension of the ink refers to the cohesive forces between the ink molecules at the liquid-air interface. It determines how the ink spreads and adheres to the substrate during the printing process. Here are some key reasons why surface tension is important in water-based gravure printing ink:
1.Ink transfer: Surface tension affects the ink transfer from the engraved cylinders to the substrate. When the surface tension is too high, the ink tends to form droplets and may have difficulty wetting the surface uniformly. This can result in uneven ink coverage and poor print quality. Conversely, if the surface tension is too low, the ink may spread excessively and cause blurred or smeared prints. Therefore, achieving an optimal surface tension is crucial for achieving precise ink transfer.
2.Wetting properties: Surface tension influences the wetting properties of the ink on the substrate surface. Proper wetting ensures that the ink spreads evenly and adheres to the substrate, forming a sharp and well-defined printed image. If the surface tension is too high, the ink may have poor wetting ability and may not spread uniformly, leading to incomplete coverage or poor adhesion. On the other hand, if the surface tension is too low, the ink may spread excessively and cause feathering or bleeding, resulting in a loss of image sharpness.
3.Substrate compatibility: Different substrates have varying surface properties, such as surface energy and porosity. The surface tension of the ink should be compatible with the substrate to ensure proper adhesion and print quality. For example, if the substrate has a low surface energy, such as plastic films, a lower ink surface tension may be necessary to promote wetting and adhesion. Conversely, substrates with higher surface energy, like coated papers, may require an ink with a higher surface tension to achieve optimal wetting and adhesion.
4.Ink stability: Surface tension also affects the stability of the ink formulation. If the surface tension is not well-balanced, it can lead to ink separation or agglomeration of pigment particles, resulting in poor ink performance and print defects. Proper control of the surface tension can help maintain the stability of the ink, preventing issues such as pigment settling, flocculation, or coalescence.
To achieve the desired surface tension in water-based gravure printing ink, ink formulators often incorporate surfactants or surface tension modifiers. These additives can help reduce or increase the surface tension of the ink, depending on the specific requirements of the printing process and substrate.
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