Recycling of post-consumer PU mattresses

 

AF - Engineering

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Reactors for industrial conversion of post-consumer polyurethane mattresses into polyol (only ENG)

According to PU Magazine the PU industry is continuing to rise despite several economic reports of the highest rates worldwide. Some 20.5 million tons of polyurethane goods were produced worldwide in 2015. This was up ca. 4% in 2014. The forecasts for 2016 indicate a slight increase to 5%.

Post-consumer mattresses situation

Around 25 million units of mattresses are produced annually in Europe. The amount of PU mattresses grows extremely fast. In 2005, the PU mattresses were 28% and in 2010 37% of the total number of mattresses produced. Exact information about the ratio is missing today, but it is assumed that 10 million PU mattresses are sold in Europe every year.

At the moment all of them are burned in order to gain energy. The disadvantages are the emerging poisonous gases and the unevenly generated energy (a major problem for industrial furnaces - for example, of cement plants). A significant drawback is, in addition, the irreversible withdrawal of raw materials from the circle of valuable substances.

AF Engineering has succeeded in creating a technology for the production of recycled polyol from a mixture of waste PU mattresses. In the course of the research, the product (recycled-polyol) has been modified to be suitable for the production of high-quality flexible or rigid PU foams. In this way, by using an environmentally-friendly product, high-quality materials was created at an extremely competitive price.

AF Engineering process for End of life (EOL) mattresses recycling

The two processes, created by AF for recycling of mattresses are completely different from each other.

The EOL PU foam waste has to be first shredded from discarded mattresses.

The recycling polyol can contain up to 50 % EOL foam waste.

The produced recycling polyols can be used for production of:

  • flexible PU foam (mattresses or furniture) at a ratio 20% recycled polyol to 80% polyether polyol. The recycling polyol has following properties:

            OH-Number [mgKOH/g]                         46-50

            Amine-Number [mgKOH/g]                   5

            η  [mPa.s]                                                       8.000   

            Acid-Number [mgKOH/g]                       < 1

  • rigid PU foam panels at a ratio 40% recycled polyol to 60% aromatic polyester polyol (АРР) or polyether polyol. The produced rigid foam showed good performance in the foaming process, foam structure and dimensional stability.The recycling polyol has following properties:

            OH-Number [mgKOH/g]                         240

            Amine-Number [mgKOH/g]                   5

            η  [mPa.s]                                                       5.000   

            Acid-Number [mgKOH/g]                        < 1

 

 

Properties of the foam products

The hydroxyl number of the recycling polyols is in the same level like the original polyols and any unusual change from Iso-Index is not necessary. This fact makes very easy the implementing of recycling polyol in already available existing polyurethane systems. The good properties of the recycling polyols enables high percentage of  original polyol replacement which makes:

  • 15-25 % for flexible foams
  • 40%-45% for panels and sandwich elements.

 

1.Properties of the flexible PU foam produced with recycling polyol

PU foam density 25 kg/m3
Master sample

(PU foam without recovered polyol)

PU foam with 20% recovered polyol
Resilience, [%] 44 43,6
Hardness, [N] 149 148
Compression set (50%) 2,4 2,6
Support factor 2,2 2,3
Elongation at break, [% ]         239% 238 %
Tensile strength, [kPa] 158 154

All parameters are in perfectly agreement.

 

2. Properties of the rigid PU foam produced with recycling polyol

The properties of the PU panels produced with 30 % recycled polyol were compared with the properties of PU panels made with original materials. The comparative data is presented in the following table:

T°C Reference 30 % Re-Polyol
CLOSED  CELLS [%] 95 95
STABILITY  at -20 °C    [%] 0,39 0,39
STABILITY  at + 90 °C    [%] 1,04 0,99
ISOTROPY  (EN 826)   2,70 2,75
TERMAL CONDUCTIVITY at different temperatures  [ƛ  = W  /  m*K   ]

(EN  12667  )

0 19,00 19,05
10 19,10 19,40
20 20,00 20,50

All parameters are in perfectly agreement.

The produced rigid PU foams show comparable properties such as traditional PU rigid foam using up to 30% recycling polyol.

 

Economic and ecological benefits

An industrially-suitable chemical procedure including process technology and system concept for producing recycling polyols from PU waste mattresses foam is also available for the first time – this is a process offering economic and ecological benefits. The costs to manufacture recovered polyol are 40-45% percent lower than the market price of the original polyol for isocyanurate rigid foam.

Ecologically, the new procedure proves its worth through increased material efficiency and sparing of resources as traditional polyols can be replaced by recycling polyols. Both productivity and energy efficiency are increased as the reaction following a comparably low temperature is carried out in a relatively short period.

Scope of delivery

  • Planning, construction and installation of an industrial (or pilot) installation for the recycling of EOL mattresses.
  • Transfer of know-how for the recycling of EOL mattresses to recycled polyol suitable for the production of flexible PU foams or for the production of rigid PU foams
  • Training for the realization of the technology on a laboratory scale.
  • Training on chemical methods for analyzing recycled polyols
  • Training for working with the industrial reactor's software.
  • Training on the service of the industrial reactor.
  • Accompanying the production to the full implementation