Polyurethane ink binder: The key film-forming component in flexible packaging printing

The polyurethane Ink Binder is the core component of the ink system. It is mainly composed of Polyurethane Resin and plays a crucial role in carrying pigments, wetting the substrate, and achieving film formation. It directly determines the core properties such as adhesion, flexibility, and resistance of the ink. It is one of the most widely used binders in the field of flexible packaging printing.

 

The core preparation is based on the polymerization reaction of polyols and isocyanates. By adjusting the ratio of soft segments and hard segments, it can precisely adapt to different printing requirements. The soft segments give the binder good flexibility and pigment wetting properties, while the hard segments enhance the film-forming strength and resistance to friction. The introduction of urea bonds can further optimize the dispersion effect, making the ink color more vibrant. 

 

According to the curing method, polyurethane ink binders are mainly divided into three types: solvent-based, water-based, and UV light-curable. The solvent-based products are easy to operate and have good stability, suitable for printing on ordinary plastic films; the water-based products have no VOC emissions and meet environmental protection requirements, and are widely used in food and pharmaceutical packaging; the UV type has a fast curing speed and low energy consumption, and is suitable for high-speed printing scenarios. 

 

Compared with other types of adhesives, it has distinct advantages: The polar groups can form a strong bond with various plastic films, with excellent resistance to bending and heat shrinkage, making it suitable for composite film processing; The pigment dispersion is excellent, which can enhance the gloss and color intensity of the ink; It has good compatibility and can be compounded with other resins to optimize performance. 

 

Currently, with the tightening of environmental protection policies and the upgrading of the industry, polyurethane ink binders are evolving towards water-based and solvent-free directions. At the same time, their performance in terms of low migration and resistance to boiling is continuously improved, better meeting the safety standards for food contact materials and facilitating the green transformation of the printing industry.