Polyurethane Binders for Inks

High-Performance Ink Polyurethane Binders The packaging sector comprises glass, metal or rigid plastic among others, with food packaging accounting for more than half of the entire segment. The distinguishing feature of food sector packaging from other sectors is its requirement for flexible packaging properties. While the benefits of flexible packaging compared to other formats are well documented, one area often overlooked is the resins entering inks. They not only make graphics and packaging more attractive but also provide functional benefits. Many different resin types enter the inks used for printing on flexible packaging—styrene acrylics, polyurethanes, polyamides, nitrocellulose and others. However, strong growth in categories such as snack foods, pre-cooked meals, meat, cheese and poultry requires multilayer laminate packaging structures. Such packaging involves reverse printing on the outer layer of the package and lamination to an inner layer. The unique requirements and challenges of such packaging highlight polyurethane resin-based ink systems. Polyurethane resins (PURs) form a flexible film and provide superior lamination bond strengths that prevent package delamination. With strong growth in food categories requiring laminated packaging, PURs distribute pigments more efficiently, provide better print quality, and keep costs and complexity low. Additionally, nitrocellulose addition is not recommended due to nitrosamines from exposure to high temperatures in packaging, and styrene acrylics are not recommended due to free radical formation. Regardless of packaging application, when white inks are concerned, the ability to achieve maximum opacity and adhesion strength is critical. The addition of other resins can reduce bond strengths and opacity. In conclusion, a PUR with the capability to grind inorganic pigment without the addition of another resin such as nitrocellulose or polyvinyl butyral helps achieve both higher bond strengths and higher opacity. Another important trend is the emergence of high-speed printing machines capable of printing at speeds higher than 2,000 feet per minute. Other improvements to be expected in the future are PURs, particularly those offering improved pigment grinding capability developed with organic pigments. The use of PURs will undoubtedly increase with growth in flexible packaging driven only by certain food categories. However, the scope of adoption depends on the ability of PURs to enable this transition.

Benefits of Polyurethane Resin

Polyurethane (PU) resin-based ink can be applied to a wide range of printing substrates without major formula changes. This advantage has two direct positive effects. Printers will need fewer ink types to print on various substrate materials used; they will maintain less ink in stock, which will have a direct positive effect on costs. Another advantage is that PU resin-based inks perform better compared to other inks. These inks, thanks to their inner flexibility and ink film resistance, are suitable for demanding operations such as retort processes or high-speed printing. New-generation polyurethane resin-based inks produced for flexible packaging deliver successful results in broader applications compared to other resin systems. The products developed at Interplast Kimya R&D Center for the ink sector, having different structures as semi-aliphatic, aliphatic and aromatic, along with: • High UV resistance, • High mechanical resistance, • High heat resistance, • Excellent bonding degree, • Efficient color strength, • High compatibility with OPP, PET, SPET, PE and others, • Excellent flexibility at low temperature, • Ethyl alcohol-free, provide solutions and innovations to the sector. Interplast Kimya's products offered to the ink sector differentiate as conventional and elastomeric, providing technical added value with high-speed operating capability and excellent adhesion for flexo and rotogravure methods. Under the PURANEX brand, non-reactive and in excellent chemical compatibility with nitrocellulose: • Puranex LM 6007 / 40 : Elastomeric systems, • Puranex LM 6000 / 70 : Conventional systems are recommended. Lale Şen Çetin R&D Center Manager Interplast Kimya Gizem İlgün PU & Application R&D Manager Interplast Kimya