Becoming carbon neutral is the ultimate goal for the years to come. By establishing a circular economy and reducing the usage of crude-oil based products, important steps can be made right away. Filter elements are often used only once and disposed after they reached a certain level of pressure drop or change interval. The recycling of such highly contaminated waste is challenging and the reverse logistics difficult, especially in the independent aftermarket. Therefore, the choice of raw materials is especially important to reduce the impact on the environment because the materials are mainly incinerated or land-filled at end of life.

The product carbon footprint can be reduced significantly by using alternative materials from recycled or renewable feedstocks. However, these materials need to fulfil all customer requirements and to pass automotive test standards. Recycled plastics are in the focus of the automotive industry to fulfil upcoming legal requirements, especially the plastic recycling rate of at least 25 % in the “Directive on end-of-life vehicles” of the European Commission. The presentation shows the industrial application of recyclate plastics, renewable feedstock for sealings and filter media resins to air, fuel, oil and cabin air filters.

Since many years gaskets made of polyurethane foam function as sealing between filter elements and their housings. These are usually petrol based 2-component systems composed of MDI (isocyanate component) and polyether polyols (polyol component). But especially for polyols, there are various possibilities to replace basic material crude oil. Polyols based on vegetable oils such as soy bean oil, sunflower oil or corn oil are available. Castor oil is a very capable type of vegetable oil to produce polyurethanes. It is possible to adjust the functionality of castor oil-based polyols by dehydration. It enables the proportionate use of renewable raw materials for the composition of lowly cross linked, flexible products such as sealings. Preserving the required mechanical properties like tensile strength, elongation, hardness and resilience and the resistance against thermal stress, chemicals and ageing challenges the creation of the material.

In addition to the design of the filter element, the filter media itself plays a crucial role in the element's performance. For air and liquid filtration, the media typically consist of a combination of a cellulose-based filtration layer and a suitable resin system. The resin significantly contributes to the media's overall performance providing stability, rigidity, and chemical resistance. Depending on the needs, a phenolic, epoxy or acrylic resin can be used to stabilize the cellulose structure and to add e.g., flame retardant properties; using Bio-based feedstocks or ISCC+ certified materials will lower the carbon footprint significantly.

The presentation shows how these alternative materials can be applied in automotive filtration. The impact on the carbon footprint as well as the reduced usage of crude oil as a resource is assessed. Furthermore, details are provided regarding functional performance and product robustness in comparison to traditional designs and materials.