Fine ink droplets create smooth color gradients and ensure the highest level of detail in the graphics.
Digital Printing in Industry
Digital printing inks for flat or 3-dimensional applications
How Functional Inks and Precise Processes Are Transforming Product Decoration
Digital printing has evolved from a purely visual discipline for promotional materials into a key process in industrial manufacturing. While in traditional graphic printing the printed image takes center stage as a carrier of information, in industrial applications printing serves as a functional coating on technical products. Materials such as plastics, glass, metals, and composites are printed on. This drastically increases the demands on chemical resistance, abrasion resistance, and adhesion. In this context, the ink droplet becomes a building block of the final product.
Our inkjet specialists analyze your requirements for adhesion, chemical resistance, and abrasion resistance, and work with you to develop the optimal process solution.
Surface Energy in Digital Printing: The Physics of Perfect Droplet Wetting
When viewed under a microscope, each individual inkjet in industrial inkjet printing resembles a precise, pinpoint landing. Within milliseconds, a microscopic ink droplet leaves the piezo nozzle, travels through the air, and strikes the substrate surface at high speed. In precisely this fraction of a second, the fate of the entire product decoration is decided: Will the droplet adhere, or will the material repel it?
What matters is not so much a mathematical ratio as the balance between the two factors. For good wetting, the surface energy of the substrate should generally be higher than the surface tension of the ink. However, the final adhesion strength is also determined by other factors, in particular the chemical interactions between the ink and the substrate, the surface morphology (e.g., roughness and porosity), and the ink’s drying and curing mechanisms.
The contact angle of the droplet on the substrate serves as a measure. A physically ideal contact angle ranges from 20 to 40 degrees. At smaller angles, the ink spreads uncontrollably, resulting in blurred edges in fine structures or barcodes. At larger angles, the droplet contracts into a sphere, leading to an uneven print image and poor adhesion.
Pre-treatments are used to prepare plastics such as polyethylene or polypropylene for digital printing. Physical processes such as corona or plasma discharges clean and activate the surface. If this is not sufficient or if the material exhibits significant porosity, a chemical primer forms the necessary bond to ensure color intensity, edge sharpness, and durability.
Printhead Technology and Fine Dosing: Precision in the Micrometer Range
At the heart of every industrial digital printing system is the printhead system, which accounts for a significant portion of a machine’s total investment. For systems with many printheads arranged in parallel, regular maintenance intervals, cleaning procedures, and controlled environmental conditions ensure operational readiness and a long service life. Lack of maintenance leads to nozzle failures, misdirected droplets, or permanent damage to the sensitive piezo elements.
In addition to maintenance, droplet size control determines the balance between dissolution and discharge.
Large droplets carry a greater volume of ink per pulse, enabling high area coverage and faster production speeds on industrial substrates.
Modern grayscale printheads dynamically vary the droplet volume and combine the advantages of fine detail with high line speed.
Specialized ink lines, such as the UVAJET series, take advantage of this range to apply both thin layers of color and tactile 3D-effect coatings with high edge sharpness to molded parts or glass.
A Comparison of Ink Technologies: The Molecular Showdown Under UV Light
After the droplet strikes the surface, the final transformation into a durable protective shield takes place. The mechanism involved depends on the ink system selected.
Radiation-curable UV and LED-UV inks offer significant advantages on non-absorbent surfaces. As soon as UV light strikes the ink droplets, the liquid components cross-link to form an extremely dense, solid polymer network. Since virtually no liquid evaporates, the process works extremely quickly, cures without delay, and requires significantly less energy compared to the evaporation of solvents or water.
Water-based inks are primarily used on absorbent materials such as paper or cardboard. They are low-emission and are ideal for primary and secondary packaging in the food industry, where strict regulatory limits on migration must be adhered to. The energy required for thermal drying of the water content must be taken into account in the overall sustainability assessment.
New Horizons Beyond the Label
While digital printing has reached maturity in traditional sign and banner printing and has also achieved very high market penetration in label printing, the primary growth is shifting to new segments.
The market for corrugated cardboard packaging, paperboard packaging, and flexible film packaging offers great potential for digital printing processes. When it comes to flexible plastics for food or consumer goods, thin material gauges and thermal sensitivities place high demands on ink development. Ongoing testing of new UVAJET formulations aims to enable printing on these substrate classes with reliable adhesion and stretch properties and to expand industrial digital printing into additional product categories.
Process Reliability in Industrial Digital Printing Through System-Wide Coordination
The successful use of digital printing systems in industrial product decoration is not an isolated process. It is more like a chain reaction based on the precise interplay of all influencing factors: from the chemical surface energy of the substrate to the optimized pretreatment and printhead control, right through to the highly functional ink specification. Only when these components are precisely aligned with one another can durable, consistent, and cost-effective print results be achieved on demanding materials.
Our specialists will support you every step of the way—from the initial material analysis and the qualification of new substrates to the fine-tuning of your process parameters.
FAQ
How does ink for industrial digital printing differ from graphic arts ink?
Graphics inks are optimized for visual parameters such as color gamut, brilliance, and edge sharpness on standard media. Inks for industrial digital printing must also fulfill functional requirements and offer high resistance to chemicals, abrasion, UV radiation, and weathering on demanding substrates.
Why is the contact angle important when printing on plastics?
The contact angle describes how the ink droplet wets the surface. An angle between 20 and 40 degrees ensures optimal droplet formation without smudging, which is the basis for high edge sharpness and reliable adhesion.
When is a primer required?
A primer is required when the surface energy of the substrate is too low for direct wetting or when the ink is absorbed too heavily by porous materials. It improves adhesion to plastics such as PE or PP and prevents the colors from bleeding.
What are the advantages of UV-curable inks over water-based inks?
UV inks cure on non-absorbent substrates in a fraction of a second, forming extremely durable surfaces, and require less thermal energy to cure than is needed to evaporate water-based systems.
In which sectors is industrial digital printing currently experiencing the strongest growth?
Now that the label market has been largely penetrated, the focus of growth is increasingly shifting to corrugated cardboard, cardboard packaging, flexible films, and specialty coatings on industrial molded parts.
Selection of UV, UV-LED and water-based inkjet ink solutions that offer added value in the individual design of product information and decorations in graphic, packaging and industrial printing.
Information material
Learn more about Digital Printing in Industry
Modern FCM technology
In line with stricter legal requirements for printing on food packaging
Ever stricter legal requirements are increasing the demands for the production of legally compliant food packaging. The right choice of ink and coating systems is therefore all the more important.
Based on current developments and the latest raw materials, Zeller+Gmelin presents you with the right solution. Modern FCM ink systems contain significantly fewer migratable substances. Together with the use of special networked initiators, Zeller+Gmelin has minimized the potential for migration. The molecular weight of the cross-linked photoinitiators (approx. 1000 Daltons) is several times higher than that of conventional photoinitiators (< 400 Daltons). They also contain polymerizable groups that participate in the curing process and are thus firmly integrated into the chemical structure of the printing ink film. These properties make the FCM systems from Zeller+Gmelin extremely safe!
Our FCM technology is more than just "low migration". It is characterized by its high-quality composition, coupled with the highest requirements and lowest migration behaviour, as well as excellent printing properties.
The advantage of conformity
- Nestlé Standard St-80.001 (Printing Inks for Food Packaging)
- Without bisphenol A and raw materials based on bisphenol A
- Swiss Commodities Ordinance 817.023.21
- GMP Regulation (EU) 2023/2006
- EU Regulation 10/2011 in its latest version
LED technology
As a specialist for radiation-curing printing ink systems of the highest quality, we also offer high-quality printing ink in the field of LED UV technology.
LED technology is particularly interesting for environmentally conscious companies that not only want to conserve resources but also protect the environment. LED technology offers an economic and ecological advantage.
LED technology has developed into a true alternative solution in the field of radiation curing! In principle, the polymerization process of an LED ink is identical to that of a UV system. The difference is that an LED system dries with a specific wavelength. The cross-linking reaction is therefore triggered by excitation in a very narrow wavelength range. Industrial LED systems can operate in a wavelength range from 365 nm to 405 nm. The most common systems are those that emit at 385 nm or 395 nm.
Environmentally friendly + energy efficient
Our printing inks are highly reactive systems which, thanks to their formulation, do not require any kind of volatile raw materials. This makes our printing inks solvent-free and emission-free! LED technology also completely eliminates the need for mercury vapor lamps. This means that you no longer have any mercury in your production process and are therefore protecting the environment. By using a specific wavelength when using LED spotlights, no ozone is produced on the machine, the heat input is reduced to a minimum and no critical UV-C radiation is emitted. This makes our LED ink solutions a user and environmentally friendly system!
- No ozone formation
- mercury-free technology
- No critical UV-C radiation
- Minimal heat input
- Low energy requirement
Profitable + Powerful
LED lamps are ready for immediate use, eliminating standby and heat-up times. You can operate the lamps in "switch on-switch off" mode and thus clock your processes. In addition, LED units can be partially switched due to their design. This enables LEDs that are not required to be switched off outside the print area. LED lamps also have a much longer service life without any loss of power. This extends maintenance cycles many times over.
- High efficiency
- Long service life
- No loss of performance
- Zone switching
- tactile
- No warm-up time
- No standby time
Analytics Center
Zeller+Gmelin has an in-house analytics center that was set up specifically for the development of low-migration inks, for raw material controls and for the internal testing of test samples.
We now also have the option of liquid chromatography with a high-resolution quadrupole time-of-flight mass spectrometer for even more precise and sensitive analyses. In addition, we always have our low-migration ink series tested and evaluated by independent analysis institutes. This double testing enables us to offer printers, packaging buyers and consumers the greatest possible product safety.
Numerous analyses have shown that when used properly with our low-migration ink series, the legal limit value of 10 ppb can not only be safely adhered to in migration tests with 95% ethanol, but can also be significantly undercut.
- Liquid chromatography with high-resolution quadrupole time-of-flight mass spectrometer (LC-QToF-MS)
- Gas chromatography with mass spectrogram (GC-MS)
- Liquid chromatography with mass spectrogram (LC-MS)
- Quality control of the raw materials we use
- Internal evaluation of test samples
Mixing with Z-Base Colors
Based on years of positive experience with monopigmented color mixing systems, we offer a monopigmented color mixing system for all our color series.
We work with the same monopigmented color mixing systems in our production facilities. This ensures fast and effective color communication between the manufacturer and the print shop. Regardless of whether PANTONE® spot colors or other common mixing color systems need to be mixed, our highly pigmented color mixing systems always achieve the best possible result. Even fan-independent shades can be optimally adjusted.
Advantages
- PANTONE® tones can be blended better
- Color mixtures are more colorful and purer, as only the pigments actually required for a color mixture are used
- the higher color intensity enables printing with low layer thicknesses
- Reduced dot gain in halftone printing
- Greater flexibility when setting the color intensity of spot colors
- fewer color shifts when viewing the printed products under different light sources (metamerism)
- Color communication between the color manufacturer and the customer is simpler and therefore faster thanks to the use of monopigmented mixing systems
- Mixing recommendations are available for all PANTONE® shades
- Color formulation, mixing and dosing systems are available in various expansion stages
- Reduction of storage costs
- Lower disposal costs for leftover paint
