Water-based pigment inks for printing on décor paper to produce laminates - an article By Marc Graindourze, Business Manager Industrial Inks, Agfa

To watch Marc participate in the recent discussion at the FuturePrint Virtual Summit - click here

Marc Graindourze explains - During the FuturePrint Virtual Summit 2 (Day 2 – Industrial – panel Interior Decoration) I have explained the potential of inkjet printing for laminates for floor and furniture. The traditional print method used in the laminate manufacturing process is gravure printing.
Gravure printing has been the standard printing technology with proven quality since decades. This technology was developed to print high to very high run lengths. It uses engraved cylinders as print masters, which are specific to each design. Its color inks are formulated in-house in view of specific print designs. It takes time to reach the exact same color each time, and the storage of the cylinders takes up a lot of space.

Why inkjet?

Inkjet printing starts directly from the design file, which means it does not need a print master. It also uses a fixed set of process colors. The design is printed by jetting of the ink droplets exactly onto each spot to obtain the desired color.
This results in many advantages:
1. Inkjet printing can be used to print very short to long run lengths; repeat jobs are easy;
2. Inkjet can be used during all stages: from the design, over test printing and proofing to real production;
3. The design freedom is huge, and specials such as company logo’s, pictures, one-off designs, etc., become easy and economical;
4. Printing of different consecutive designs without stopping or with a very short change-over time becomes realistic.

This way, inkjet provides an answer to two key market trends:

1. A very short make-ready time, which also allows for lower stocks at every stage (at the deco printer, the laminate producer and at the dealer as well as the DIY shop);
2. Laminate applications have become a fashion item. While once the number of designs was limited, the offering now covers a broad selection of designs, with new trends very year.
Inkjet is best placed to match these demands.

Various inkjet printing options
Inkjet printing can be implemented in compliance with the existing pre- and post-processes, which is important to avoid extra investments by the laminate producers.
Different inkjet systems offer different levels of output:
• Wide-format (multi-pass) printing has been popular for many years for proofing and very short run lengths. A high-speed multi-pass inkjet printer such as Agfa’s InterioJet delivers an output of up to 340 m²/ hour, thus extending the run length.
• Single-pass printing is the solution for covering a high percentage of production run lengths. High-speed inkjet at full width (over 2 meters) and at a linear speed of above 100 m/min results in profitable economics, as these printing systems combine a high output with a short change-over time between designs.

Ink as the key element
Developing an inkjet ink for printing on décor paper for laminate production requires a combination of three key elements:
1. Tuning the ink to the laminate production process
The ink formulation needs to be fully compatible with the next steps of the laminate production, as this will contribute to the lightfastness and durability of the laminate. The ink wetting behavior on the décor paper controls the image quality; the selection of the pigments determines the color gamut;
2. Printing performance and reliability:
Ink formulations are developed for specific print heads to be able to guarantee jetting reliability. They also fit the overall print system design (e.g. the dryers) to deliver consistent prints day after day;
3. Consistent print results:
The ink formulation and production are tuned to deliver excellent batch-to-batch ink consistency for color and image quality, so that the ink delivers consistent prints day after day.

Water-based inks comprise a pigment dispersion, which is obtained by a milling step. Next to water, the ink carrier contains organic co-solvents which regulate ink jetting, ink wetting and speed of drying.
The selection of pigments is defined by the laminate application, and takes into account the following requirements:
1. reproduction of wood colors;
2. obtaining low metamerism;
3. high level of color constancy;
4. good lightfastness.

Therefore, the ink set comprises Cyan, Red, Yellow and Black inks. The pigment type and concentration are fine-tuned to result in a color gamut covering all wood designs, as well as low metamerism and high color constancy.
The ink formulation is mastered by means of the selection and the amount of each compound, and by means of the production technology. Only when all these aspects are perfected, can the ink’s performance meet all requirements, including the all-important jetting reliability i.e. the guarantee that every jetted drop reaches its exact target spot over the full width and at a high printing speed – day after day, batch after batch, design after design.

Thanks Marc - great article - If you would like to see the session that Marc took part in at the recent FuturePrint Virtual Summit click here