Recycling of flexible PU foam
Chemical PU recycling is represented by several technologies which have their advantages and disadvantages.
As a result of years of research and experimentation, AF specialists have succeeded in creating highly efficient and functional recycling systems for polyurethane waste.
The process developed by AF Engineering is based on reaction between dicarboxylic acids and the urethan chain. In contrast to other developments, the use of dicarboxylic acids does not lead to the formation of any primary aromatic amines such as toluene diamine (TDA) and methylene diamine (MDA) that are classified as carcinogenic.
As a result of the permutation, a recycling polyol is received as well as small amounts of condensed water originating from the humidity contained in the PU flakes.
Up to 50% of PU waste can be incorporated into recycled polyol, making the product extremely economical.
Properties of the recycling polyol based on flex PU foam wastes:
||4,000 -7,500 mPas
||40 - 58 mg KOH/g
||< 1 mg KOH/g
||< 6 mg KOH/g
||light to dark brown liquid depending on the colour of the waste foam
|No primary aromatic amines !!!
Hydroxil number is in the same level like the basic polyol and any change from Iso-Index is not necessary. This fact makes very easy the implementing of recycling polyol in already available existing polyurethane systems. Such good properties of the polyol enables high percentage of basic polyol replacement which makes 20%-25% for bedding and upholstery foams and even higher amount for technical foams like sponges or rollers.
The essential properties of a typical flexible PU block foam produced with 20% recycling polyol are following:
||Foam density 25 kg/m3
(foam without recovered polyol)
|Foam with 20% recovered polyol
|Compression set (50%)
|Elongation at break, %
|Tensile strength, [kPa]
All parameters are in the range of the control samples.
The example is taken for conventional foams with density 25 kg/m3. All parameters such as compression set, hardness, resilience, support factor, tensile strength and elongation at break remain in the range of the control samples. Even slight improvement of resilience can be observed. The foams also do not contain any volatile organic compounds (VOC). All the tests were carried out by the independent institution.