As the flexible packaging industry accelerates toward higher sustainability standards, faster production speeds, and greater substrate diversity, ink technology is being pushed to evolve at an unprecedented pace. Regulatory pressure, recyclability targets, and raw-material volatility are forcing printers and converters to rethink long-established nitrocellulose (NC) systems often without compromising on print quality, productivity or cost efficiency.

Against this backdrop, DF Inks, the flexible packaging inks business unit of DRUCKFARBEN Group, has introduced PU Ultima, a next-generation polyurethane (PU) ink series designed to deliver maximum performance, broad application coverage, and a practical pathway toward NC-free production 

Rather than positioning PU Ultima as a niche specialty solution, DF Inks has developed it as a PU, NC-free platform capable of supporting both flexographic and rotogravure printing across a wide spectrum of demanding applications from surface printing and laminates to retort structures and wet wipes.

One Platform, Wide Application Coverage

One of the defining characteristics of the PU Ultima series is its exceptional versatility. The system has been engineered to cover applications ranging from surface printing (with OPVs) to high-end lamination, including retort laminates and chemically demanding structures such as wet wipes packaging. 

This wide application range allows converters to move away from maintaining multiple ink series each optimized for a specific substrate or end use and instead consolidate around a single, high-performance PU platform. In practical terms, this means fewer ink changes, reduced storage complexity, faster set-ups, and consistently high-speed print performance.

PU Ultima inks demonstrate excellent adhesion and bond strength on substrates commonly used in flexible packaging, including PE (standard and MDO-PE), PP, PET, BiOPA, acrylic films, PVDC-coated films, AlOx/SiOx barrier films, and EVOH/PVOH-coated structures. This robust adhesion ensures ink integrity even under challenging mechanical conditions such as flexing, stretching, and downstream lamination.

Engineered for Chemical and Thermal Resistance

As packaging formats evolve toward higher functionality—retort, hot-fill, and aggressive contents—ink resistance properties become critical. PU Ultima inks are formulated to offer high resistance to chemicals, oils, and solvents, making them suitable for applications where the printed structure is exposed to demanding environments, including wet wipes and food packaging for sauces, soups, pet food, and condiments. 

Thermal resistance is another key advantage. PU Ultima inks are designed to withstand the elevated temperatures associated with retort and sterilization processes, positioning the series firmly within the high-performance segment traditionally dominated by more complex ink chemistries.

Printability at Speed: Performance Without Compromise

From a pressroom perspective, PU Ultima was developed through extensive real-world printing trials under realistic production conditions. The result is a system that delivers excellent printability across the full tonal range from highlights and halftones to full solids without sacrificing speed or consistency.

The inks feature high color strength, enabled by higher pigment loading. In flexographic printing, this allows converters to achieve high ink density using low-cell-volume anilox rollers (around 500 l/cm, 3–3.5 cm³/m² for CMYK), reducing overall ink consumption while improving detail reproduction in highlight areas.

In gravure applications, PU Ultima inks are formulated as ester-rich systems, making them compatible with solvent recovery installations. Print speeds exceeding 600 m/min are achievable with optimal ink transfer, while superior solvent release ensures solvent retention levels below 8 mg/m². PU Ultima remains fully compatible with standard alcohol and acetate solvents, minimizing disruption during transition from conventional ink systems. 

High-Opacity White for Demanding Laminated Structures

A critical component of the PU Ultima portfolio is UND 450 W 0005, a high-opacity polyurethane-based white ink developed for rotogravure printing in laminated structures. The ink delivers excellent opacity, flexibility, and resistance, while maintaining strong adhesion across a broad range of substrates.

Designed for high-demand applications, UND 450 W 0005 offers high heat resistance (up to 160–180°C) and has demonstrated suitability for retort and sterilization processes under internal laboratory testing. The ink exhibits strong bond and seal strength in laminated PET structures and maintains excellent flexibility, scratch resistance, and blocking resistance key parameters for high-performance flexible packaging.

With a recommended application quantity of up to 2 g/m², the product supports both performance efficiency and material optimization, making it particularly suitable for converters operating in regulated food and non-food packaging segments.

Designed for Recycling and Circularity

One of the most significant drivers behind the development of PU Ultima is sustainability—specifically recyclability and compatibility with mechanical recycling streams.

PU Ultima inks are PVC- and NC-free, addressing two materials increasingly scrutinized within recycling processes. Polyurethane-based binders demonstrate excellent color stability, no gassing or odor formation, and regranulate performance comparable to virgin material, supporting high-quality mechanical recycling outcomes.

DF Inks has aligned PU Ultima with evolving design for recycling guidelines for PE and PP packaging structures, supporting limited ink coverage, appropriate pigment selection, and total ink weight thresholds in line with current
EU recommendations.

Certified for Recycling: Independent Validation

Reinforcing its sustainability credentials, the PU Ultima system has achieved “Made for Recycling” certification by Interzero, based on recyclability testing from Fraunhofer IVV and formal evaluation by bifa Umweltinstitut GmbH. This independent validation confirms compliance with strict EU circularity criteria for flexible packaging, including mono-material compatibility, mechanical recyclability, and alignment with upcoming PPWR requirements.

A key product within this certified portfolio is PUV001L0002 – PU Ultima Matte OPV, a 1K polyurethane-based matte overprint varnish specifically designed for PP and PE mono-material structures. The product combines surface aesthetics with performance and regulatory compliance, without compromising recyclability.

All certified products were tested across EU markets and confirmed suitable for polypropylene-based flexible packaging, achieving material recovery rates of up to 99% a critical benchmark for brand owners pursuing circular packaging strategies.

Enabling the Transition: The PUX Hybrid System

Recognizing that an immediate transition away from NC systems is not always operationally feasible, DF Inks has complemented PU Ultima with PUX, a hybrid technological varnish designed to enable a gradual, controlled shift toward NC-free production.

PUX can be blended with NC-based systems to create PU/NC hybrid inks with minimized NC content, supporting future PPWR compliance thresholds (≤ 0.8% w/w NC). Fully compatible with PU Ultima, PUX ensures formulation stability, predictable print performance, and seamless press operation, while also enabling press-return optimization and reduced waste.

A Practical Pathway Forward

Rather than forcing converters into abrupt change, DF Inks positions PU Ultima and PUX as a practical, performance-driven pathway toward the future of flexible packaging inks. Together, they allow printers to streamline ink inventories, optimize production efficiency, maintain high PU performance standards, and progressively reduce reliance on NC systems—without compromising print quality or productivity.

As regulatory demands intensify and brand owners push for recyclable, high-performance packaging, PU Ultima exemplifies a new generation of ink technology, where sustainability, operational efficiency, and print excellence converge.