Filter material and filter element produced therefrom

Abstract

The invention relates to a filter material comprising a carrier material that is impregnated on one side with a thermally pre-crosslinked binder system (VB) and on the other side with a thermally crosslinkable but un-crosslinked binder system (UB). The filter material is characterised by improved deformability and a very good level of heat sealability, particularly using ultrasound, and a low pressure differential particularly when filtering high-viscosity liquids.

Claims

1. Filter material comprising a wet-laid nonwoven, a dry-laid nonwoven, a woven or a foam, the filter material having a first side and a second side, wherein the first side of the filter material is impregnated with a first binder system, and the second side of the filter material is impregnated with a second binder system, the first binder system is different than the second binder system, the first binder system is not present on the second side of the filter material, the second binder system is not present on the first side of the filter material, the first binder system is a pre-crosslinked binder system, the second binder system is a crosslinkable, but not yet or little crosslinked binder system, the pre-crosslinked binder system is thermally crosslinked to 30 to 80% of the theoretical final crosslinking thereof after a heat treatment step at below 120° C., and the crosslinkable, but not yet or little crosslinked binder system is thermally crosslinked to a maximum of 30% of the theoretical final crosslinking thereof after a heat treatment step at below 120° C.

2. Filter material according to claim 1, wherein at least one of the first and second binder systems penetrates the filter material by at least half and at most three quarters of the thickness thereof.

3. Filter material according to claim 1, wherein each of the first and second binder systems penetrates the filter material by at least half and at most three quarters of the thickness thereof.

4. Filter material according to claim 1, wherein the filter material has an acetone extract of from 50 to 100% on the non-crosslinked side and from 0 to 50% on the pre-crosslinked side.

5. Filter element comprising a filter material according to claim 1.

6. Filter element according to claim 5, wherein connection regions of the filter material are joined and thermally welded together in each case by the second side, which is impregnated with the not yet or little crosslinked binder system.

Description

(1) The invention is described in the following in greater detail by way of example with reference to the drawings, in which:

(2) FIG. 1 is a schematic sectional view through a first embodiment of the filter material according to the invention;

(3) FIG. 2 is a schematic sectional view through a second embodiment of the filter material according to the invention;

(4) FIG. 3 is a schematic view through a third embodiment of the filter material according to the invention;

(5) FIG. 4 is a plan view, vertically from above, of a first embodiment of a filter element folded into the shape of a star; and

(6) FIG. 5 is a plan view, vertically from above, of a second embodiment of a filter element folded into the shape of a star.

(7) FIG. 1 schematically shows a section through a first embodiment of the filter material according to the invention. A pre-crosslinked binder system VB penetrates the filter material from a first side 1 by 50% of the thickness thereof, while a non-crosslinked binder system UB also penetrates the filter material from a second side 2 by 50% of the thickness thereof.

(8) FIG. 2 schematically shows a section through a second embodiment of the filter material according to the invention. The pre-crosslinked binder system VB penetrates the filter material from the first side 1 by 75% of the thickness thereof, while the non-crosslinked binder system UB penetrates the filter material from the second side 2 by 25% of the thickness thereof.

(9) FIG. 3 schematically shows a section through a third embodiment of the filter material according to the invention. The pre-crosslinked binder system VB penetrates the filter material from a first side 1 by 25% of the thickness thereof, while the non-crosslinked binder system UB penetrates the filter material from the second side 2 by 75% of the thickness thereof.

(10) FIG. 4 is a plan view, vertically from above, of a first embodiment of a filter element folded into the shape of a star. A ring consisting of a filter material according to the invention folded from a zig-zag, for example the filter material shown in FIGS. 1 to 3, is closed, in that the second side 2 comprising the non-crosslinked binder system UB of one end of the ring, which forms a first connection region 3a, is placed on the second side 2 comprising the non-crosslinked binder system UB of the other end, which forms a second connection region 3b, and the two ends are joined together in a suitable manner, in particular by means of ultrasonic welding. In this embodiment, the second side 2 is on the inside of the filter element according to the invention. The connection regions 3a, 3b project laterally outwards beyond the star-shaped contour of the filter element.

(11) FIG. 5 is a plan view, vertically from above, of a second embodiment of a filter element folded into the shape of a star. The ring consisting of the filter material according to the invention is closed, in that the second side 2 comprising the non-crosslinked binder system UB of the first end of the ring, which forms the first connection region 3a, is placed on the second side 2 comprising the non-crosslinked binder system UB of the other end, which forms the second connection region 3b, and the two ends or connection regions are joined together in a suitable manner, in particular by means of ultrasonic welding. In this embodiment, the second side 2 is on the outside of the filter element according to the invention, the connection regions 3a, 3b projecting into the interior of the filter element.