Polyurethane ink binder

The polyurethane Ink Binder is the core component of the ink, mainly composed of polyurethane (PU/PUU) resin. It is formed by polymerizing polyester/polyether polyols, isocyanates, and chain extenders. It serves as the "pigment carrier" and "key for film formation" of the ink, determining the adhesion, film formation, and printing suitability of the ink. 

 

Its main types can be classified into four categories: single-component evaporation type (easy to operate, low cost, suitable for plastic soft packaging surface printing), two-component reaction type (strong adhesion, resistant to boiling, suitable for food composite printing), water-based polyurethane (environmentally friendly with low VOC, used in environmentally friendly scenarios such as food packaging), and UV light-curing type (no solvent, fast curing, suitable for special printing of labels). 

 

1.Core advantages are prominent: adjustable flexibility, suitable for film bending and bag making; broad adhesion, especially excellent for PET/PA substrates; good pigment wetting property, with vivid color display; aliphatic type has low odor and is resistant to yellowing, meeting the requirements of food packaging, and has good compatibility with various resins. 

 

2.Key points for formulation and selection: For yellowing resistance, choose aliphatic isocyanates; for cost considerations, aromatic ones should be preferred. The ratio of two-component should be controlled at a NCO/OH molar ratio of 1.0 to 1.2. For reactive type, it needs to be aged at 40 to 60℃. Selection can be matched according to the scenario: for ordinary printing plates, single-component is selected; for composite steaming, two-component aliphatic is selected; for environmental protection requirements, water-based or UV type is selected; for non-polar substrates, an adhesion promoter needs to be combined. 

 

It is mainly applied in plastic soft packaging, food and drug packaging, labels and special printing for metals, etc. It is the core ink raw material that balances performance and environmental protection.