Siegwerk’s CIRKIT coatings: pioneering sustainable solutions with UPM and DG Press for a circular future Oliver Waddington, Global Business Development Lead, Circular Economy Coatings (CEC) Business Unit, Siegwerk

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2. Fat, Oil & Grease
Unlike glass, aluminum, and some laminated structures,
which provide effective barriers against fats, grease, and oils,
paper lacks the properties needed to block these substances. This
limitation makes uncoated paper unsuitable for packaging products
that are sensitive to grease leakage, such as snacks, baked goods,
and ready-to-eat meals. Grease, fat and oil can seep through
uncoated paper, causing staining, compromising the package’s
appearance, and even weakening its structural integrity.
CIRKIT coatings are engineered to address these
vulnerabilities by providing an effective barrier against fats, grease,
and oils. The coatings form a continuous, defect-free layer over the
paper surface, preventing the migration of these substances and
maintaining the integrity of the packaging.
3. Sealability
Secure seals are a fundamental requirement in many
packaging applications, ensuring that the contents remain contained
inside and protected from external contaminants, maintaining
freshness, and even providing tamper evidence. However, achieving
reliable seals with paper-based materials can be challenging,
particularly in high-speed production environments where
consistency and precision are critical. Therefore, paper requires
specialized coatings to enable effective sealing.
Siegwerk’s CIRKIT range includes coatings specifically
designed to enhance the sealability of paper-based packaging.
These coatings enable wide operational sealing windows on
packing lines, allowing for the creation of paper-based packs without
compromising on efficiency.
4. Additional Functional Enhancements
In addition to moisture resistance, barrier protection, and
sealability, functional coatings can also impart other desirable
properties to paper-based packaging, including:
•
Heat Resistance: Ensuring the packaging can
withstand high temperatures during processing,
storage, or consumer use (e.g., microwave or ovensafe packaging).
•
Printability: Providing a smooth, uniform surface that
enhances print quality, allowing for high-resolution
graphics, brand messaging, and product information.
•
Flexibility and Foldability: Maintaining the mechanical
properties of the paper, ensuring it can be folded,
creased, or shaped without cracking or delaminating
the coating.
•
Anti-Static and Anti-Stick Properties: Reducing static
buildup and preventing products from sticking to the
packaging surface, which is particularly important for
confectionery and bakery products.
Siegwerk collaborates closely with industry partners,
including paper mills, converters, and brand owners, to optimize
the functionalization process. By conducting extensive testing
and validation, we ensure that our coatings not only meet the
technical requirements of each application but also align with the
environmental goals of our customers and the broader packaging
industry.
Through continuous innovation and a collaborative
approach, Siegwerk is enabling the next generation of paper-based
packaging solutions.
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Coating applications across the value chain: online,
offline, and in-line varnishing
As discussed, in the production of paper-based packaging,
coatings play a critical role in enhancing the substrate’s functional
properties, such as barrier protection, sealability, and printability.
The point at which these coatings are applied within the value chain
signi昀椀cantly impacts their performance, production ef昀椀ciency, and
overall cost-effectiveness.
Coatings can be applied online (during paper production),
offline (after the paper has been produced), or as an in-line
varnish during the printing process. Each application method has
its strengths, weaknesses, and ideal use cases. Selecting the
appropriate method depends on the desired properties, production
constraints, and end-use requirements.
1. Online Coating
Online coating refers to the application of functional coatings
directly on paper or board during its production on the paper/board
machine. This process often uses specialized equipment for highspeed applications.
Strengths:
•
High-Speed Application: Online coating is performed
at the same speed as the paper machine, allowing for
rapid production and high throughput.
•
Cost-Effective: By integrating coating into the paper
production process, manufacturers can reduce the
need for additional processing steps, minimizing
handling and logistics costs.
•
Drying capacity: Modern online coating systems often
utilize contactless drying methods, such as infrared (IR)
or hot air, which help achieve consistent drying without
damaging the substrate.
Weaknesses:
•
Limited Flexibility: Online coating processes are
less adaptable to small production runs or customized
formulations, making them more suitable for highvolume, standardized products.
•
High Setup Costs: The integration of coating systems
into the paper machine requires signi昀椀cant capital
investment and technical expertise.
•
Contact Drying Constraints: Coatings applied online
by Film or Size Press which are then in contact with
drying cylinders must be optimized to dry quickly
without tackiness, which can limit the types of
formulations that can be used.
Best Fit:
Online coating is ideal for large-scale production of
packaging grades requiring low-to-mid barrier performance, such as
food wraps and industrial packaging.
2. Offline Coating
Offline coating involves applying functional coatings to the
paper or board after it has been produced, using separate coating
machines such as air knife, rod, or curtain coaters. This process can
be conducted anywhere in the value chain, including at a Paper/
Board Mill converter facility, or a specialized coating plant.
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