It is common practice to bind active materials such as activated carbon with polyurethane adhesives, especially in automotive cabin air filters. Furthermore, the use of PU as a binder has disadvantages during processing and subsequent operation. In particular, outgassing and the release of VOCs should be mentioned in this regard. For example, the nozzles tend to clog when the application is applied according to the state of the art. With UV-active dyes, an uneven application of the adhesives can be detected, but the application itself remains problematic.

To solve this and other problems, a process has been developed which enables the integration of the active substances into the meltblown process and thus ensures that they are bound. The activated carbon is held directly by the filaments of the meltblown nonwoven. The process not only eliminates PU or other adhesives, whose technical disadvantages result from the filters, but also enables cost savings. Furthermore, a deep-knitted fabric with several superimposed layers is possible in order to increase the loading.