Overview
Sappi is a global leader in fibre-based products, offering flexible paper packaging with integrated heat-sealing properties and barriers against oxygen, water vapour, grease, aroma, and mineral oil.
Recognising the growing need for high-quality codes on barrier paper packaging for global food brands, Sappi partnered with Domino Printing Sciences to find the optimal coding solution.
Domino’s D-Series laser coders were employed to code a selection of six different Sappi products. In every instance, they delivered clean, crisp codes without compromising the barrier properties of the packaging.
Fast Facts
- Sappi is a leading player in barrier papers for flexible packaging.
- Since 2013, Sappi has spearheaded over 100 innovative packaging projects, covering applications such as tea, chocolate, cereals, and tobacco.
- The company’s barrier papers are fully recyclable and designed to meet future regulations on recyclable packaging, including the EU’s goal to make all packaging recyclable or reusable by 2030.
- Sappi’s paper products are made from wood pulp sourced from responsibly managed FSC and PEFC-certified plantations within 100km of their manufacturing plants.
Project Background
Sappi has developed a range of barrier papers to replace conventional, non-recyclable multi-material plastic composites. This product range includes water-based barrier coatings that protect against moisture, oxygen, aroma, grease, and mineral oil.
“Our packaging materials are tailored to meet various customer needs,” says Mike Zywietz, Product Application Engineer at Sappi. “We begin by assessing the product requirements and current packaging materials, then select one or two barrier papers from our portfolio for further testing.”
“However, replicating performance is just one aspect. We also need to ensure that our materials integrate smoothly into existing customer production lines, which often use multi-layer materials,” Zywietz explains. “Since brand owners typically need support for the entire value chain, we collaborate closely with leading manufacturing companies to provide expert solutions.”
In developing their new range of barrier papers, Sappi partnered with Domino to evaluate the effectiveness of laser coding on the finished packaging materials.
Coding Requirements for Barrier Papers
Sappi’s barrier papers offer a sustainable alternative to plastic composites across various applications, including:
- Block bottom bags for dried ingredients like sugar and pasta
- Flow wrappers for snacks, chocolate, and confectionery
- Pouches and lids for fresh and processed foods
While coding requirements differ based on specific customer applications, all food packaging lines generally need to print mandatory best before and use by dates, as well as standard batch and product codes. Increasingly, food and beverage manufacturers are seeking advanced coding solutions, such as 2D codes for enhanced data sharing and traceability.
“We’re seeing a growing demand from brands to incorporate 2D codes on their packaging. This trend not only aids in product traceability but also meets consumer expectations for more detailed product information,” explains Mike Zywietz.
“Adding this information during the initial packaging design phase is impractical, as traceability codes require unique information for each batch or individual product,” Zywietz continues. “Laser technology allows for the addition of 2D codes at the end of the packaging process, enabling new codes to be added alongside required codes in milliseconds, without altering the printing image or packaging design, and without incurring extra costs.”
How Did Domino Select the Appropriate Solution?
CO2 lasers are ideal for paper packaging, so Domino began by determining the most effective type of CO2 laser. To identify the optimal laser wavelength, Domino’s specialists conducted FT-IR spectroscopic analysis on six different Sappi barrier papers to evaluate their response rates.
“Spectroscopic analysis helps identify which laser wavelength interacts best with the substrate material,” says Dr. Stefan Stadler, Team Lead at the Domino Laser Academy. “This analysis led us to recommend our D-Series blue tube CO2 laser as the optimal solution for Sappi’s barrier papers.”
The graph above illustrates the response of the substrate to Domino’s blue, black, and red tube CO2 lasers, with the blue tube laser showing a slightly more favourable absorption rate. Additional suitability testing confirmed that the D320i blue tube laser is the optimal choice.
In code quality evaluations, the D320i produced crisp, clear codes on barrier papers, effectively handling both simple messages like best before dates and batch codes, as well as more intricate designs, including graphics and scannable 2D codes.
How Did Domino Ensure That the Laser Did Not Compromise the Paper’s Integrity?
Domino’s laser specialists produced post-coding 3D microscopic images of Sappi’s barrier paper samples to closely examine the formation of the code. This analysis ensured that the laser did not compromise the integrity of the paper while delivering high-quality coding.
How Did Domino Ensure That the Laser Did Not Compromise the Paper’s Integrity?
Domino’s laser specialists produced post-coding 3D microscopic images of Sappi’s barrier paper samples to closely examine the formation of the code. This analysis ensured that the laser did not compromise the integrity of the paper while delivering high-quality coding.
The coded materials were then sent back to Alexander Schröder, Product Application Engineer at Sappi’s R&D centre, for further barrier testing to assess whether the laser coding impacted the papers’ barrier properties.
To evaluate the oxygen and water vapour barriers, Sappi employed permeability analysers to measure the water vapour transmission rate (WVTR) and oxygen transmission rate (OTR) of the products. The functional papers were placed between two chambers, one filled with nitrogen gas and the other with air or water vapour. Infrared sensors then measured the oxygen or water particles in the nitrogen chamber over time to calculate the transmission rate. A similar method was used to assess the hexane vapour transmission rate (HVTR) to evaluate grease and mineral oil barrier properties.
The results, shown in the chart below, confirmed that Domino’s D-Series CO2 laser coder did not significantly impact the barrier properties of any of the tested papers.
The results displayed in the graphs are normalised values with a 10% variation, which is within the normal range. For instance, with very low oxygen transmission rate (OTR) measurements (<3 cc(m².d)), a 10% variation equates to just 0.3 cc(m².d), well within acceptable limits.
“We were very impressed with the results of the barrier testing,” says Mike Zywietz. “Combined with the high quality and clarity of the codes, Domino’s D-Series proves to be an excellent choice for Sappi’s customers.”
The Domino Difference
Following successful testing of Sappi’s barrier papers, a team from Sappi visited the Domino Laser Academy to observe sample testing from the customer’s perspective.
“This was a highly positive experience,” Zywietz notes. “We gained firsthand insight into the coding process for our barrier papers and saw the advanced test and measurement equipment used in routine sample testing. The laboratories are exceptionally well-equipped.”
“The visit highlighted the value of involving end users in the sample testing process to help identify the best solution,” Zywietz adds. “We would recommend a visit to the Domino Laser Academy to any of our food packaging customers seeking a coding solution.”
Looking to the Future
The demand for sustainable product packaging is expanding, and innovations in alternatives to hard-to-recycle flexible plastics, such as Sappi’s barrier papers, are expected to advance over the coming years.
“The flexible packaging market is vast, but many current solutions are either challenging or impossible to recycle. Significant efforts are needed to develop sustainable alternatives,” says Ingo Kaiser, Marketing Communications Specialist at Sappi.
“At Sappi, we are investing in a new coating machine at our Alfeld manufacturing plant, which will enhance our flexibility, space, and capacity to develop new sustainable packaging alternatives,” Kaiser continues. “We will keep collaborating with suppliers to facilitate the transition to barrier papers for manufacturers.”
“This recent collaboration with Domino has been very successful, and we look forward to many more successful projects in the future,” he concludes.
The project with Sappi exemplifies how Domino supports manufacturers on their sustainability journey. As a coding and marking provider, Domino continues to seek partnerships with innovative packaging providers to identify solutions for new sustainable packaging types.
