Groundbreaking invention finds multiple applications

At the University of Helsinki, Professor Ilkka Kilpeläinen is leading research into new types of solvents that enable the manufacturing of textiles from pulp as well as replace the plastics in cleaning products with biodegradable microbeads. The latest application is the ability to glue wood – without using glue.

Ilkka Kilpeläinen is Professor of Organic Chemistry at the University of Helsinki. He is shown holding up a set of small glass vials, which contain what appear to be tiny plastic granules. However, the beads are not made of plastic, but of cellulose.

In the future, these biodegradable grains could supplant the plastic microbeads that are currently used in products such as toothpastes and detergents. The environmental impact of plastic microbeads from wastewater being carried into rivers and lakes has raised significant concern among researchers in recent years.

The new biodegradable microbeads are just one application of a new method for dissolving cellulose that has been developed at the Department of Chemistry of the University of Helsinki. The process allows cellulose fibers to be dissolved efficiently and non-toxically by utilizing a new type of ionic liquid solvent. The method is highly flexible, as it allows the use of diverse raw materials ranging from cellulose to recycled paper and discarded clothing.

“The solvents that we have developed are organic salts with a unique set of properties. For example, they are fully recyclable and non-toxic,” Prof. Kilpeläinen says.

Cellulose becomes a dress fabric

The first application of the process was an eco-friendly method for manufacturing textile fibers, developed in collaboration with Aalto University. The result of the research was the Ioncell process that can be used to replace cotton or viscose. Viscose requires highly toxic carbon disulfide when it is manufactured from cellulose.

“From the beginning, our goal was to create a fiber material that was as high-quality as possible. In its tensile strength properties, Ioncell is on a par with hemp, so it’s really strong.”

The University of Helsinki has collaborated with Aalto University and the forest industry on the project. So far, production of the fiber has been limited, but in the next few years, the new material may progress to manufacturing on a commercial scale. The first company to try out the new invention was Finnish design house Marimekko, which unveiled a print-patterned dress made from Ioncell fabric in 2014.

Gluing wood without glue

The Ioncell process has many more practical applications, such as the manufacture of cellulose-based materials that are extremely lightweight. Small cellulose balls can be made highly porous, thus trapping air inside the material.

“A cubic meter of this kind of material only weighs about 30 kilograms, and due to the large amount of air contained in its pores, it has great insulating properties. The material could potentially replace styrofoam packing,” Kilpeläinen says.

The latest Ioncell application is using the ionic solvent to join pieces of wood together. “It’s kind of like gluing wood without glue. One could describe it as chemical welding for wood,” explains Kilpeläinen.

The method involves applying a small amount of the solvent on the wood surfaces to be joined. The parts are then pressed together and the used solvent is removed. The solvent dissolves the cellulose and lignin in the joint area, and the parts are fused together upon drying. The joint is so tight that it is difficult to discern even with an electron microscope.

“During heating, the solvent evaporates, so it can be collected for reuse,” Kilpeläinen explains. He notes that ionic solvents for cellulose are widely known, so it’s surprising that no one had thought of trying to ‘glue’ wood with them. “Because it works like a charm!”

Kilpeläinen expects a host of other applications to be discovered for the versatile Ioncell process. “The biggest challenge is actually the difficulty of choosing where to focus the research.”

Comprehensive patent portfolio

The University of Helsinki and Aalto University have applied for approximately a dozen patents for the Ioncell process and its related products. The universities also hold joint patents.

“Our patent portfolio is shaping up to be pretty substantial, all the way from the solvents to the manufacturing processes and end products,” says Kilpeläinen. When applying for patents for Ioncell products and processes, the University of Helsinki has had the support of Seppo Laine Oy’s patent expertise.

“Seppo Laine’s patent attorneys are skilled in constructing strong patent applications, and the collaboration has been very smooth in every way,” says Professor Kilpeläinen.

Text: Matti Remes