Recycling flexible foam scrap into polyol takes a step forward

Rampf claims first in making polyols from waste flexible foam

By Liz White, editor

A startling amount of all the flexible foam made globally – up to 30 percent – ends up as process waste, according to Fraunhofer ICT expert Dr Ulrich Fehrenbacher.

Flexible foam is made in huge blocks and then cut to shape/size, leaving a considerable amount of offcuts as scrap. In Germany this amounts to 20 kilotonnes per annum (ktpa), and to about 145 ktpa in the EU (Germany makes 95 ktpa and the EU 750 ktpa of new foam annually), Fehrenbacher said.

About half of all flexible foam made goes into furniture and mattresses, 20 percent each goes into vehicle uses (cars, trains and planes) and the construction sector, with 10 percent going into other uses, according to Fehrenbacher.

He listed three main routes for foam recycling:

• Thermal energy recovery (24-30 MJ/kg);
• Material recycling or rebonded foam (for US carpet underlay, a saturated market and hence a relatively low value product); or
• Chemical recycling (solvolysis).

Glycolysis of rigid foam is an established chemical recycling route, used as an industrial process, while solvolysis/acidolysis for flexible foam is at an early stage, Fehrenbacher told the audience at the FSK meeting in Essen, Germany, 21-22 Nov.

To make rebonded foam, producers grind flaked foams, mix it with a binder and form it into composites. Mechanical properties of these materials are limited, so their value is low.

So there is demand for better routes, Fehrenbacher said, to generate improved material qualities and hence better value.

A joint German research project led by the Fraunhofer ICT research institute in Pfinztal involved Rampf Ecosystems GmbH & Co. KG of Pirmasens, Metzeler Schaum, based in Memmingen, and Keil Anlagenbau in Hunteburg.

This work optimised acidolysis, in order to develop standard recycled polyols for block foam manufacture. This project also aimed to integrate the recycling process into the facilities of block foamers, said the Fraunhofer researcher.

In acidolysis, the scrap material is reacted with various ingredients for several hours and then filtered and processed. This degrades the PU into linear polyols and disperses it in a stabilised form to give a reactive polyol.

“Our goal was to have high process reliability,” Fehrenbacher said.

He pointed out that foam makers need to adapt their PU processes to use these secondary polyols.

The production cost of the recycled polyol lies between E1.4 and 1.7/kg, as compared to E1.8/kg for conventional polyol. The work indicated that, with secondary polyol use, the system cost could be cut to E1.49 /kg as opposed to E1.69/kg with standard (virgin) polyol. This work was done using a formulation with 65 percent polyol, 30 percent isocyanate and 5 percent additives.

The research also raised the ecological profile of acidolysis by optimising the process with low-emission catalysts and stabilisers. Low emissions are important for flexible foam, and levels can be cut by 50-60 percent, with the right ingredients, Fehrenbacher indicated.

According to the Fraunhofer expert, the pilot plant will be expanded in cooperation with various producers of soft foam, combining several foams to get better quality polyols.

He also noted that about 15 percent of virgin polyol replacement is the appropriate amount: “If you use more polyols, the physical properties get worse,” he commented.

“Foams would be harder and I can’t imagine producing mattress foam with 40 percent of recycled polyol.”

A recycling specialist

Rampf Ecosystems, which specialises in recycling polyurethane and PET, says it has been designing recycling solutions to recover raw materials from polyurethanes for all kinds of requirements for the last 20 years – in the face of rising raw materials prices.

“The way we think and act is focused on customer needs – a fact that derives from our many years of experience in the polyurethane sector,” said Marco Werth, sales and marketing director at Rampf Ecosystems. The aim is to develop engineering technology to recycle all polyurethane waste, while factoring in economic considerations.

This work tackles the challenges posed by dwindling resources.

The company, which has been part of the Rampf Group since 2003, says it views PU production residues and post-consumer PET from packaging not as waste but as valuable sources of raw materials.

These materials are also turned into polyols, known as Recypols or Petols, which then flow back into the PU production chain.

Rampf Ecosystems has also strengthened its systems supply business, in order to market the recycled polyols more effectively. As a result, these high-quality products are used in a wide variety of industries.

Industrial scale acidolysis

Rampf Ecosystems says it has been operating the world’s first industrial plant for manufacturing polyols from flexible polyurethane foam waste since April 2012.

The company researched the acidolysis process intensively in 1994-97 in collaboration with Aalen University and published positive findings from a joint project on recycling foams in 1999.

Rampf first applied the process to making secondary polyols on a small scale (unveiled at UTECH Europe 2009).

After further process engineering and plant optimisation, the company succeeded in scaling up acidolysis from a 10 to 100 kg scale to a semi-industrial one (1000 kg) and then up to its present industrial scale of 7 tonne/batch, 3500 tonnes/annum – in 2011. In 2012 Rampf begun industrial production of secondary polyols using this facility.

The system allows high-quality raw materials to be recycled for re-use in the foam manufacturing industry.

According to Rampf, loss of valuable raw materials and high disposal costs for waste materials in production processes “are now a thing of the past.”

Acidolysis makes it possible to recover polyols industrially from flexible slabstock and flexible moulded foams.

Rampf Ecosystems is now recycling large quantities from well-known slabstock foam manufacturer Metzeler Schaum.

The acidolysis facility – “the world’s first usable industrial plant” for acidolysis of flexible foam – was designed and completed as part of the joint project, funded by the German Federal Ministry of Education and Research.

“Skills networks are the recipe for success for groundbreaking innovations,” said Rampf, who worked closely on the project with its partners, listed above.

The resulting high-tech plant offers a recycling capacity of around 3500 tonnes per year.

Such plants can also be used to recycle raw materials in foam manufacturing facilities. In these cases, Rampf Ecosystems can provide the chemical know-how and coordinate the plant engineering. Slabstock foam producers can have local cost-effective, sustainable recycling that helps deliver active environmental protection, said Rampf.