- Tanneries rely on research for eco-friendly processes.
- Nanotechnology leading to leather with innovative properties.
- Team studying leather aging and restoration.
INTEREST in preserving animal skins has a long history that dates back to prehistoric times, but in the 21st century, leather goods have become ubiquitous.
To produce leather, animal skins must be tanned to stop the natural process of decomposition. This is achieved by applying a chemical treatment that acts on collagen fibers in the skin and stabilizes the proteins. Currently, this chemical change is brought about using vegetable, synthetic and, most frequently, mineral agents; chromium salts are now used in the tanning of 90% of the leather produced in Europe.
Tanning also includes mechanical processes that complement the treatments applied to skins. When the tanning process is completed, products are added in the finishing stage to give the leather the desired physical and aesthetic properties.
In recent decades, the number of craft workshops has declined. Small-scale operations have been replaced by industrial producers that take advantage of technology and seek to innovate.
These modern tanneries face the challenge of purifying the large volume of wastewater they produce and disposing of chemical byproducts. In more developed countries, industrial producers rely on research and development programs to make their processes as environmentally friendly as possible and to produce high-quality products.
Global production of tanned leather is concentrated in 20 countries, led by China.
More than half of production in eighth-ranked Spain is based in Catalonia, and much of this activity is concentrated in a tanning cluster around Igualada, Spain, which is home to the Igualada School of Engineering (EEI), a school associated with the Universitat Politecnica de Catalunya BarcelonaTech (UPC), which is internationally recognized in leather engineering.
EEI and the University of Northampton in the U.K. are the only schools in Europe that offer university-level studies in tanning. The expertise of EEI researchers plays a key role in driving innovation in tanneries.
The team, led by Anna Bacardit and Lluis Olle -- members of UPC's Engineering & Biotechnology Research Group and of the A3 Chair in Leather Innovation -- participates in national and international projects, particularly looking at the environmental improvement of tanning processes and products.
In the Chrome-Free project, supported by the Centre for the Development of Industrial Technology, the team is working on processes that use chrome-free tanning agents to produce high-end leathers. Chromium(III) is the chemical agent used in tanning. If chromium(III) is oxidized, it turns into toxic chromium(IV), so researchers are looking for alternative products to stabilize collagen proteins.
The large-scale use of vegetable agents such as tannins, which are extracted from chestnut trees and other trees and shrubs, has many drawbacks, including the risk of deforestation. This is why the team is involved in another European project known as Lowest.
"In this project, we're developing synthetic agents that are economically competitive and work at least as well as the tanning agents currently in use," Bacardit said.
Research is also paving the way for leather producers to make leather of higher quality and with innovative new properties, which is possible thanks to nanotechnology, by which scientists can explore the properties of materials at the nanoscale.
The A3 Chair in Leather Innovation is developing new nanostructured materials that are applied in the finishing stage of the tanning process to improve the functional properties of leather products.
In the Nanopelltech project, researchers are working closely with a number of companies to improve the upholstery used on seating for public spaces and vehicles. The project is part of a program of technological innovation clusters funded by ACC1O, an agency that supports innovation in Catalan firms and their internationalization efforts.
The A3 Chair is the technology partner of the five companies involved in the project. The team has developed new nanomaterials that add antibacterial, flame-retardant and self-cleaning properties to leather and fabric for seating.
"By creating nanostructured surfaces that repel dirt, we make seating easier to maintain and more hygienic," Olle said. This improves the health and safety of users, who also benefit from better fire-retardant treatments. The conventional approach is to apply such treatments directly to the leather or fabric, but thanks to nanotechnology, encapsulated products can now be applied.
"These products are only activated if there's a fire, so under normal conditions, people don't come in contact with them," Bacardit added.
The leather used in seating also incorporates nanocapsules that perform a self-repairing function. If a small scratch is made on the upholstery, they release a product that covers the damaged spot.
These nanostructured products were developed in collaboration with two companies: Colorantes Industriales, which conducted the formulation study, and Eco Poltech, which synthesized the nanomaterials.
Bacardit stressed that "the project has taken advances in nanotechnology beyond the lab and helped companies incorporate nanomaterials in their production processes -- an essential step if the research is to benefit society."
The researchers have worked with Curtits Aqualata, which produced the leather for upholstery; Figueras International Seating, a company that made a prototype seat for use in public spaces, and Aunde, which produced a seat for buses. The prototype made by Aunde has been installed on two buses and is being tested to validate its functional characteristics.
Research on tanning is adding value in many areas beyond the fashion industry. The knowledge investigators are gaining about collagen materials opens up the possibility of applying biotech techniques in sectors such as cosmetics and pharmaceuticals. Relationships are also being developed with the paper industry, the graphic arts sector, the chemical industry and even cultural industries.
The A3 Chair research team is currently studying how leather ages in order to improve its restoration. The research is being carried out within the framework of a European project aimed at creating a tool for assessing damage and deterioration in leather and parchment items held by museums and in other historical collections.
Launched by the European platform Eureka, the ADAS project brings together organizations and companies based in Romania and Spain, including Curtits Aqualata.
The Spanish company has commissioned the research team to simulate the aging processes that leather undergoes. The information obtained will be entered into a database to facilitate the study and dating of historical items. The research results will also be made available to companies that make facsimiles and reproductions of documents.
"The research will make it possible to reproduce original items -- the leather cover of an ancient manuscript, for example -- more quickly, more economically and with better-quality results. At present, reproductions of this kind are generally made using traditional methods that don't give consistent results," Olle said.
The A3 Chair in Leather Innovation, established in early 2012, is a joint initiative of UPC (through EEI), the Igualada City Council, the Association for Research in Leather & Related Industries and the Spanish Chemical Association for the Leather Industry.