Polyurethane (PU)
Ink Binder is a kind of polymer material with excellent performance. Because of its excellent adhesion, wear resistance, flexibility and chemical resistance, it has been widely used in various ink systems and packaging fields.
1. Applicable ink types
(1)Polyurethane binders mainly react with other resins (such as alkyd resins) or curing agents to form dense paint films, which are mainly used in the following types of inks
Gravure printing ink and flexographic printing ink: These are the main application fields of polyurethane binders. Especially in the soft packaging industry, it is used to make polyurethane surface printing ink and polyurethane inner printing (composite) ink.
Surface printing ink: printing on the surface of packaging materials requires high gloss, abrasion resistance, scratch resistance and good outdoor weather resistance. Polyurethane ink can meet these requirements well.
Inner printing (composite) ink: printed between two films (e.g. combined with another film by adhesive after printing). This kind of ink requires good adhesion to the substrate, good compatibility with the
Composite Adhesive and no rejection. Polyurethane system is excellent in this respect, and the peeling strength is high after compounding.
(2)Special ink
Cooking resistant ink: used for food packaging that needs high temperature and high pressure sterilization (such as above 121℃). Polyurethane binder can form a stable cross-linked network, which does not change color and fall off during high-temperature cooking, ensuring the integrity and safety of packaging.
Medium-resistant ink: used for packaging containing oil, acid, alkali, alcohol and other contents. Polyurethane paint film can effectively resist the corrosion of these chemicals and prevent the pictures and texts from being destroyed or migrated to the contents.
2. The applicable packaging field
(1)Based on the above ink characteristics, polyurethane ink binders mainly serve the flexible packaging market with high performance requirements
Food and beverage packaging: this is the largest application market.
Ordinary food bags: such as snacks, biscuits and noodles.
Liquid packaging: vertical bags and aluminum-plastic composite packaging for liquids such as milk, juice, soy sauce and vinegar. The ink is required to be resistant to penetration of contents.
Heavy packaging: such as rice and pet food packaging bags, ink is required to be wear-resistant and not easy to wear during transportation.
Cooking and packaging: used for packaging bags that need high temperature sterilization, such as cooked meat and military rations.
(2)Daily chemical and pharmaceutical packaging
The packaging of shampoo, shower gel and other washing products requires that the ink be resistant to grease and surfactant.
Drug packaging: especially the packaging of drugs for external use and medical devices that need to be kept sterile, the ink is required to be pure, stable and resistant to chemical disinfection.
(3)Industrial and special packaging
The protective film and label of some industrial products require the ink to have outdoor durability.
Packaging with special functions such as anti-migration and anti-counterfeiting is needed.
Summary
In a word, polyurethane ink binder has become the core raw material of high-performance gravure and flexographic ink by virtue of its comprehensive and balanced physical and chemical properties. It is especially suitable for the field of flexible packaging with strict requirements on weather resistance, chemical resistance, high-temperature cooking resistance and composite strength, and is widely used in high-end packaging products related to daily life and safety, such as food, beverage, daily chemical and medicine, which provides a reliable, beautiful and safe printing solution for modern packaging.
