Enameling Technology

Recirculation through the recycling of water-based overspray in a modified water-based filler paint

A pilot plant for the recovery of overspray of water-based paint has been successfully tested over a 15-month period in a car bodywork paint shop. Overspray has been reconcentrated by ultrafiltration, then recycled as a modified filler paint with the addition of a newly-developed compensating paint. Technical paint requirements have been substantially fulfilled.

 

Summary

To date, the disposal of overspray from the surface painting of car bodies in the painting booth has been undertaken in a blast furnace or in cement production. Initial success in the recycling of car paints has been achieved with filler paints, which form a functional layer between the metal of the car body and the surface paint.

 

Based upon trials for the recovery of water-based paint overspray for the production of a modified filler paint in a pilot plant, this project involved the incorporation and optimisation of a pilot plant in the routine operation of a car bodywork paint shop.

 

This objective incorporated the following stages:

The collection, stabilisation, defoaming and recovery of water-based paint overspray;

Analysis of the circulation water;

The optimisation of the ultrafiltration plant for the reconcentration of solids in the water-based paint overspray;

The development of an appropriate compensating filler paint.

 

Results:

 

  • Water-based paint overspray has been recovered in the pilot plant over a 15-month period on a largely trouble-free basis.
  • Stabilisers and chemical antifoaming agents have not influenced the completion of the process and the quality of the recycled material.
  • The long-term completion of the water cycle has been possible, without the accumulation of contaminants or excessively increased emissions.
  • The ultrafiltration plant has achieved the satisfactory retention of solids. The process-related clogging of membrane surfaces has restricted the service life of filter modules to 2 – 6 months.
  • A modified anthracite-coloured filler paint has been developed on the basis of recycled water-based paint overspray, together with a new compensating paint with satisfactory technical paint qualities.
  • Scaled up to the complete paint shop, reductions in both costs and primary energy consumption have been achieved.

More Project Information

Project title: Paint recycling 2000: recirculation through the recycling of water-based overspray in a modified water-based filler paint

Project number: 1461074/0

Project period: 1997 - 1999

Project region: Germany (Baden-Württemberg, North Rhine-Westphalia)

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Source: German National Library of Science and Technology Hannover (TIB)