Nonwovens out of thin air?
What could nonwovens be made of in the future? Today spunmelts are made primarily from synthetic fibres such as polypropylene, polyester and polyethylene, and drylaid nonwovens from synthetics as well as natural materials such as cotton, cellulose, viscose and bast fibres.
More recently, new biopolymers such as PLA have lent themselves readily to the spunmelt process, but there are now major expectations for the development of 100% bio-based synthetics like PET polyester.
At the 2015 World Expo, which recently closed its doors in Milan, Coca Cola displayed the world’s first PET plastic bottle made entirely from plant materials, and it’s believed the technology underpinning it could eventually become widespread both for plastics and for fibres – including those employed by the nonwovens industry.
Polyester is a synthetic polymer generally made of two components – PTA (roughly 70%) and MEG (30%). It’s the successful substitution of synthetic MEG with a bio-based replacement that has been the initial success story for Coca Cola in the drive to replace its PET bottles with renewable alternatives, as part of its PlantBottle programme.
Since the 2009 launch, Coca-Cola has distributed more than 35 billion bottles in nearly 40 countries using its current version of PlantBottle packaging, which is made from up to 30% plant-based materials.
Importantly, this Bio-PET can be made in Coca Cola’s existing oil-based plastic production plants without having to make any significant investments in new infrastructure.
Over the past couple of years, however, the drinks giant has worked intensively with a number of pioneering chemical companies to develop a bio-based paraxylene to enable the production of 100% bio-based plastics and fibres, beyond the BioPET which has been produced to date.
Now, it appears, this has been achieved – although it is yet to be established when a BioPET 100 bottle – let alone a nonwoven product made with the technology – could be appearing commercially.
Carbon dioxide
It is estimated that, since its launch, the use of Coca-Cola’s PlantBottle packaging has helped save the equivalent annual emissions of more than 315,000 metric tons of carbon dioxide.
But what if carbon dioxide itself were to become the basis of raw materials?
In fact, Covestro – until September this year known as Bayer MaterialScience – has already started a programme based on exploiting CO2 as a precursor for the manufacture of polyurethane foam.
The company is currently constructing a €15 million line with a 25-ton chemical reactor at its site in Dormagen in Germany to produce an annual 5,000 metric tons of a polyol containing 20% CO2, to initially be used in making polyurethane foam mattresses.
“Improving the sustainability of everything we do is an integral part of our business strategy and we have now succeeded in turning a waste gas that is potentially harmful to the climate into a useful raw material,” said Covestro CEO Patrick Thomas.
Over in the USA, meanwhile, a new method for taking carbon dioxide directly from the air and converting it to oxygen and nanoscale fibres made of carbon has been developed at George Washington University.
Professor of Chemistry Stuart Licht says his group’s newly demonstrated STEP process – which both captures the carbon dioxide from the air, and employs an electrochemical process to convert it to carbon nanofibres and oxygen – is more efficient and potentially a lot cheaper than existing methods of producing carbon fibres. At the same time, it captures more solar energy than the most efficient solar cell or photoelectrochemical processes.
“It’s also a means of storing and sequestering carbon dioxide in a useful, stable and compact manner,” says Licht. “If the process is powered by renewable energy, the result is a net removal of carbon dioxide from the atmosphere.”
Green polyolefins, such as those developed by Braskem in Brazil, are another possible route for nonwovens to reduce their utilisation of fossil feedstock-based monomers. This approach, producing polymers with exactly the same properties – including mechanical – from renewable resources instead of oil, has also been taken by BASF who already offer polyacrylate superabsorbents made partly from renewable source-based acrylic acid.
New developments in raw materials for nonwovens, along with the latest cutting-edge research and development centres worldwide, are always prominent at INDEX – the leading nonwovens show which next takes place at Palexpo from 4th-7th April 2017.
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