Firma Carl Freudenberg

Carl Freudenberg Kg

Wolfram Schultheiss

Klaus Schmidt

Harald Hoffmann

Armin Greiner

Felix Herberg

Silke Frank

J&ouml;rg St&ouml;ckler

A multi-layer air filter is described, including a filter layer which is covered by a prefilter layer on the dust-laden gas side, which has a laid dry electrostatically effective nonwoven fabric, preferably a staple fiber nonwoven fabric, whose area weight is 10 through 100 g/m . In particular, the filter may be used as a vacuum cleaner bag.

Air filter having electrostatically active nonwoven fabric inliners and their use

The present invention relates to a pleated filter made of a multi-layer filter medium, including at least one filter paper layer having area weights of 30-100 g/m , a microfiber nonwoven fabric layer having area weights 5-120 g/m and a support nonwoven fabric layer made of synthetic, polymeric fibers having area weights of 10-120 g/m . The layers of the pleated filter contain fused polymer areas by which the fabric layers are bonded to the paper layer, and by which the fabric layers are made firmer within themselves. When subject to a fractional efficiency test at an initial pressure difference of at most 180 Pa, at a boundary speed of approximately 2.62 m/s and a flow speed through the filter medium of approximately 0.13 m/s, the pleated filter is able to separate at least 90% of particles greater than 0.3 &mgr;m, at least 92% of particles greater than 0.5 &mgr;m, at least 93% of particles greater than 1 &mgr;m, and at least 97% of particles greater than 3 &mgr;m, as measured using the standard method DIN EN 60312 (IEC 60312) &sect; 5.1.2.5.

Pleated filter made of a multi-layer filter medium

A fibrous filter mat of which all or a part of the fibers are coated totally or at least in part with a mixture of at least two dye components which are insoluble in one another, one of said components being fat- and/or oil-soluble and of a color which contrasts with that of the fiber blend and/or of the other component, the other component being fat- and/or oil-insoluble. The mat is especially suited for kitchen exhaust hoods since entrapment of fats and oils causes a color change as the oil-soluble dye dissolves and spreads out.

Filter mat

A nonwoven fabric having a smooth surface, especially for use as support material for semipermeable membranes, comprising a support mat into which at least one surface thereof, an open-structured, continuous covering layer of fine, thermoplastic particles is calendered.

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Weinheim, Germany

Wolfram Schultheiss