Research on the Adhesion Technology of UV Flexographic Ink on Paper
Date: Feb 08 2025 From: Star Color
In the thriving printing industry,
UV flexographic ink has gradually become a new favorite in the market due to its significant characteristics of being environmentally friendly, efficient, and high in printing quality. In various printing applications, the adhesion performance between ink and paper is crucial, as it directly determines the quality and durability of printed products. For example, in food packaging printing, poor ink adhesion not only affects the aesthetic appeal of the packaging but may also contaminate food; in book printing, ink that is not firmly attached can degrade the reading experience. Therefore, an in-depth analysis of the adhesion technology between UV flexographic ink and paper is of great significance for expanding the application scope of UV flexographic ink and enhancing printing effects.
1.Influence of Paper Characteristics on UV Flexographic Ink Adhesion
The types of paper used for printing are diverse. Most papers are conducive to printing, while a few, due to their smooth surfaces, result in inadequate ink adhesion. Some common papers have rough surfaces, which provide better adsorption for ink and do not pose an adhesion issue. For instance, newspaper provides a larger attachment area for ink, favorable for mechanical anchoring, but may lead to uneven ink penetration, affecting printing quality. On the other hand, papers with smooth surfaces like coated paper have a small ink attachment area, making it difficult to adhere through mechanical anchoring. Special treatments, such as coating with polar group layers to increase affinity, are often required.
The fiber structure of paper is also crucial. Long-fiber papers, such as cotton fiber paper, have strong fiber bonding, large pores, and easy ink penetration with strong adsorption and high adhesion firmness. Short-fiber papers, like straw pulp fiber paper, have weak fiber bonding, small pores with uneven distribution, and difficult ink penetration, leading to ink accumulation on the surface and poor adhesion. In addition, when ink is printed along the fiber arrangement direction, penetration resistance is reduced, resulting in better adhesion.
2.Influence of Ink Formulation on Adhesion
Different types of resins have varying effects on the adhesion performance between ink and paper. Acrylate resins have fast curing speeds, high hardness, and strong chemical corrosion resistance but poor flexibility, which may cause ink film cracking in applications where bending is required. Polyurethane acrylate resins combine good flexibility and wear resistance, making them more suitable for such scenarios.
The compatibility between resin and paper is also important. Resins with strong polarity, such as those containing hydroxyl, carboxyl, and other polar groups, can form strong bonds with polar paper surfaces through intermolecular interactions, improving adhesion.
Pigment dispersibility affects adhesion uniformity. Well-dispersed pigments allow the ink to spread and adhere more evenly on the paper surface, whereas poor dispersion can lead to uneven color and ink film thickness. The interaction between pigments and resins also affects adhesion, as pigments containing active groups can form chemical bonds with resins, enhancing adhesion.
In terms of additives, adhesion promoters can enhance adhesion by forming chemical bonds or physical adsorption between ink and paper. Rheological additives can adjust the rheological properties of ink, enabling it to better fill the surface irregularities of paper, increasing contact area and adhesion, and also improving leveling to enhance printing quality.
3.Influence of Printing Process Parameters on Adhesion
Appropriate printing pressure enables ink to be fully transferred to the paper surface and tightly contacted, improving adhesion. Insufficient pressure results in low ink attachment, shallow color, and poor adhesion; excessive pressure can cause ink deformation and excessive spreading, affecting pattern clarity, potentially damaging paper structure, reducing adhesion, and accelerating wear on plates and equipment.
Printing speed needs comprehensive consideration. Too fast a speed leads to insufficient curing time for ink under UV exposure, resulting in incomplete curing, weak bonding with paper, and issues like ink film detachment and fading. Too slow a speed reduces production efficiency, increases costs, and affects ink rheology and transfer characteristics, subsequently impacting adhesion.
The intensity and duration of UV exposure should be appropriate. Adequate exposure intensity and time ensure complete ink curing, but excessively high intensity can cause excessive surface curing of the ink, forming a hard shell with incomplete internal curing, reducing adhesion, and potentially aging and degrading pigments and resins. Too short an exposure time results in incomplete ink curing and insufficient adhesion; too long increases costs and may damage paper. Optimal parameters need to be determined through experiments based on factors such as ink formulation and paper light resistance.
The adhesion technology of UV flexographic ink on paper is influenced by multiple factors, including paper characteristics, ink formulation, and printing process parameters. By reasonably adjusting these factors, adhesion performance can be effectively enhanced, improving the quality of printed products. Huizhou Zhongzhixing Color has been dedicated to enhancing the adhesion and printing effects of UV flexographic ink. Through years of unremitting efforts, UV flexographic ink now exhibits good adhesion on most materials and possesses weather resistance capabilities such as high temperature resistance, acid and alkali resistance, and water washability. If you are also interested in UV flexographic ink, please feel free to contact us.
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