Air filter with powder adhesive

The challenge

For this air filter, the client wanted a powder adhesive applied on one side to adsorb the activated carbon. The adhesive had to be as strong as possible to maintain a low proportion of thermoplastic (as it has no filter effect). The material also had to be inexpensive and withstand temperatures of 90 degrees, but the melting point could not be too high. Furthermore, both adhesives needed to be almost emission-free.

Activated carbon was mixed with a polymer. In a second step, this composite was bonded with a needle felt (fibre web) using a thin CoPA web.

The path to our solution

We carried out a series of tests with different polymers in various particle sizes in order to find a suitable mixture ratio. Following another test series of various adhesive webs (as thin as possible), we found one that offered optimum adhesive strength while only minimally preventing the filter effect.

The solution

To conclude the project: we found a polymer that is both inexpensive (available in a special granulation adapted to the carbon) and able to adsorb the activated carbon well. We also found a suitable product to bond the fibre web, in the form of a very thin co-polyamide web, woven from a low-emission co-polyamide. Both products meet requirements for thermal stability and emissions and are produced using a proprietary formula.

The adhesive system is suitable for series production in the automotive industry for all larger OEMs. All of the desired specifications were fulfilled. Comprehensive quality documentation was created to ensure long-term quality.