To ensure that corrugated cardboard retains its stability when exposed to moisture, so-called wet-strength agents are added to the starch adhesives used for bonding the corrugated cardboard. In the research project ‚BioWellKleb‘, the PTS – Institut für Fasern & Papier gGmbH and the Fraunhofer Institute for Silicate Research ISC have developed a bio-based and formaldehyde-free wet-strength agent for this purpose.
As part of the research project, a team of scientists has developed a biobased and formaldehyde-free adhesive that improves the stability of corrugated cardboard in the presence of moisture. By using bioadhesives, the packaging industry could not only improve its environmental footprint but also reduce the use of problematic chemicals. The achieved adhesive strengths reach up to 85 percent of the values of conventional reference products. This development opens up a perspective for replacing fossil-based adhesive products with biobased alternatives in the future.
However, developing a biobased adhesive brings some challenges. One of the biggest hurdles is achieving the same performance as conventional products.
The goal of BioWellKleb was to develop wet-adhesion agents based on bioOrmocer for starch adhesives. Ormocer materials are inorganic-organic hybrid polymers developed at the Fraunhofer ISC. They combine organic and inorganic components at the molecular level. In bioOrmocer materials, additional biomolecules are also incorporated into the material structure. They can be based, for example, on cellulose or starch; chitosan can also be used.
Promising formulations
At the Fraunhofer ISC, the researchers selected suitable starting materials and adapted the systems to water-based starch adhesives. For laboratory experiments, the bioOrmocer systems were added to a standard starch adhesive. Concentrations of two to five percent could be homogeneously incorporated into the starch suspension. Promising formulations were subsequently prepared in quantities of five to 25 liters and tested under practical conditions.
In addition to the wet strength, the project team investigated the mechanical properties of the corrugated cardboard, such as edge and flat-surface resistance to penetration and impact. The recyclability was not affected by the newly developed wet strength agents. Before industrial use, the systems need to be further optimized, for example by adjusting their molecular structure and the quantities used.
Fraunhofer ISC offers technology transfer
The Fraunhofer ISC offers technology transfer to interested companies for further developed bioOrmocer wet adhesives. This enables companies to produce the required quantities themselves – for example 50 tons per year.
The research project BioWellKleb aims to create important foundations for the future use of biobased and formaldehyde-free wet adhesives in corrugated board production.
The Federal Ministry of Agriculture, Food and the Interior (BMLEH) has funded the project through the project promoter Fachagentur Nachwachsende Rohstoffe e. V. (FNR).
SourceSpecialized agency for renewable raw materials
