Residual contents of PUR foam cans
Packagings of filled materials containing pollutants, such as PUR foam cans, require special infrastructure for their take-back and recovery under the Packaging Ordinance. They cannot be collected and disposed of via dual systems. A previous bifa report on behalf of PDR Recycling GmbH + Co KG (PDR) confirmed this system incompatibility of used PUR foam cans.
Foam cans with residual content
The PUR foam cans taken back by recycling depots, DIY stores and the trade contain substantial quantities of residual contents. Working on behalf of PDR, bifa examined the extent to which technical circumstances and user behaviour are responsible for these residual contents. To this end, following an analysis of previous investigations into the quantity of residual contents, more than 70 cans of different types and manufacturers were emptied under simulated construction site conditions.
Two main reasons for residual quantities were identified:
- the removal of the adapter or foam applicator following partial extraction of material and
- the pot life of the cans between two uses or their direct disposal following partial extraction.
These causes very frequently result in sealing of the can valve; the user can no longer empty the packaging and substantial pressure and medium to large residual quantities remain in the can. The ageing of the material in case of lengthy non-use of filled cans led to residual contents of more than 5 % in the majority of the tests.
Other factors such as the adjustment of the foam applicator, the angle at which the can is held during use and the ambient temperature only resulted in slightly increased residual contents. Despite different designs of the examined one-pack foam cans, the valves used, the overall height, the diameter or the design of the head and bottom of the cans were all not found to have any significant influence.
Therefore, user-induced causes are essentially responsible for the quantity of residual contents. The design of the cans does not have any noteworthy effect.