A new manufacturing process uses lasers to seal paper packages instead of glue

Although paper is a more environmentally friendly packaging material than plastic, it is often contaminated with additives, such as the adhesives used to create a secure seal. This complicates the recycling process and reduces the quality of recycled paper. Now, German researchers at four Fraunhofer Institutes have done just that developed an alternative process that can seal paper packages Without glue or plastic using a process that includes a carbon monoxide laser.

The new system, now called Project Papure, leverages the expertise of the Fraunhofer Institutes, each of which focuses on areas such as polymer research, engineering and packaging, and laser beam technologies. The first step of the new sealing process involves analyzing the chemical composition and shape of different types of paper using techniques such as scanning electron microscopy and X-ray photoelectron spectroscopy to determine whether they can be sealed without an additive. The amounts of ingredients such as hemicellulose, cellulose, lignin, talc and calcium carbonate present in paper can affect the strength of final package seals.

Once the paper is type approved, it is irradiated with a CO2 laser in a controlled process that rapidly heats its surface, converting lignin, hemicellulose and cellulose into short-chain compounds. From there, what researchers call “fusible division products” remain on the surface of the paper and act like natural glue, creating an airtight seal when heat and pressure are applied. Researchers are still fine-tuning various parameters of the Papure project, including laser intensity and the design of the paper’s seams, to maximize the strength of the bonds. But in current testing, they found that the seal, which is only 2 cm wide and 3 mm wide, is strong enough to withstand a 44-pound load.

Researchers have already built a “laboratory-scale modular manufacturing unit for paper processing” capable of producing the flat, four-sided paper bag design commonly used today by Companies like Lego. They are also working to simplify and downscale the design of laser and seal modules and incorporate measurement systems that can evaluate the quality of the seals being produced and automatically adjust various settings to ensure they meet a specific bond strength target. By the end of September 2026, their goal is for the pilot machine to produce 10 packages per minute.