Pleated air filter with bridging filaments and continuous-contact filaments

1. A pleated air filter media comprising an upstream face and a downstream face and a plurality of oppositely-facing pleats with a pleat direction and with a plurality of upstream pleat tips and upstream pleat valleys and downstream pleat tips and downstream pleat valleys,

wherein the pleated air filter media comprises a plurality of upstream linear bridging filaments that are extrusion-bonded to at least some of the upstream pleat tips of the pleated air filter media,

and,

wherein the pleated air filter media comprises a plurality of downstream continuous-contact filaments that are extrusion-bonded to the downstream face of the pleated air filter media.

2. The pleated air filter media of claim 1 wherein a ratio of an average diameter of the upstream linear bridging filaments to an average diameter of the continuous-contact filaments is at least about 3.0:1.0.

3. The pleated air filter media of claim 1 wherein a ratio of an average diameter of the upstream linear bridging filaments to an average diameter of the continuous-contact filaments is at least about 5.0:1.0.

4. The pleated air filter media of claim 1 wherein all of the upstream linear bridging filaments are parallel to each other, are spaced along the pleat direction, and are oriented orthogonal to the pleat direction; and, wherein the downstream continuous-contact filaments are at least substantially parallel to each other; are spaced along the pleat direction, and are oriented at least substantially orthogonal to the pleat direction.

5. The pleated air filter media of claim 1 wherein the upstream linear bridging filaments comprise an average center-to-center spacing of at least 8.0 mm and wherein the downstream continuous-contact filaments comprise an average center-to-center spacing of at most 4.0 mm.

6. The pleated air filter media of claim 1 wherein the upstream linear bridging filaments comprise an average center-to-center spacing of at least 10.0 mm and wherein the downstream continuous-contact filaments comprise an average center-to-center spacing of at most 3.0 mm.

7. The pleated air filter media of claim 1 wherein the pleated air filter media comprises an average pleat height of at least about 20 mm.

8. The pleated air filter media of claim 1 wherein the pleated air filter media is at least generally incompressible along a folding direction of the pleated air filter media, and wherein the pleated air filter media is at least generally laterally compressible along the pleat direction of the pleated air filter media.

9. The pleated air filter media of claim 8 wherein the pleated air filter media is laterally compressible so that the pleated air filter media exhibits a lateral compression ratio of at least 1.5.

10. The pleated air filter media of claim 1 wherein the pleated air filter media comprises a nonwoven fibrous web comprising organic polymeric fibers at least some of which are of a composition that comprises electrets.

11. The pleated air filter media of claim 10 wherein the upstream linear bridging filaments and the downstream continuous-contact filaments are organic polymeric materials of the same composition as at least some organic polymeric fibers of the nonwoven fibrous web.

12. The pleated air filter media of claim 1 wherein the pleated air filter media comprises a nonwoven fibrous web that is a spun-bonded nonwoven web.

13. The pleated air filter media of claim 12 wherein the pleated air filter media consists essentially of a spun-bonded nonwoven web that comprises organic polymeric fibers of a composition that comprises electrets.

14. The pleated air filter media of claim 12 wherein the spun-bonded nonwoven web is a high-loft web that exhibits a solidity of less than 8.0.

15. The pleated air filter media of claim 1 wherein the pleated air filter media further comprises a plurality of downstream linear bridging filaments that are at least substantially parallel to each other, are spaced along the pleat direction, are oriented at least substantially orthogonal to the pleat direction, and are extrusion-bonded to at least some of the downstream pleat tips of the pleated air filter media.

16. The pleated air filter media of claim 1 wherein the pleated air filter media further comprises a plurality of upstream continuous-contact filaments that are at least substantially parallel to each other, are spaced along the pleat direction, are oriented at least substantially orthogonal to the pleat direction, and are extrusion-bonded to the upstream face of the pleated air filter media.

17. An air filter comprising the pleated air-filter media of claim 1 .

18. The air filter of claim 17 wherein a perimeter support frame is mounted to four major edges of the pleated air-filter media so that the air filter is a framed air filter.

19. A method of filtering air, the method comprising:

positioning the air filter of claim 17 in an air-handling system; and, operating the air-handling system so that moving air is motivated through the pleated air-filter media so as to filter the air motivated therethrough.

20. A method of making a pleated air filter media comprising upstream linear bridging filaments and downstream continuous-contact filaments, the method comprising:

extruding a first plurality of molten streams of organic polymeric material and partially solidifying the molten streams into a plurality of first parallel, spaced-apart, elongate, partially-solidified filaments;

bringing the first partially-solidified filaments into contact with a downstream face of a moving, flat, fibrous air-filtration web so that the first partially-solidified filaments are in continuous contact with the downstream face of the fibrous air-filtration web;

allowing the first partially-solidified filaments to solidify into downstream continuous-contact filaments that are bonded to the downstream face of the fibrous air-filtration web;

then,

folding the fibrous air-filtration web into a pleated configuration;

extruding a second plurality of molten streams of organic polymeric material and partially solidifying the molten streams into a plurality of second parallel, spaced-apart, elongate, partially-solidified filaments;

bringing the second partially-solidified filaments into contact with upstream pleat tips of the pleated fibrous air-filtration web so that the second partially-solidified filaments are in discontinuous contact with the upstream face of the fibrous air-filtration web;

and,

allowing the second partially-solidified filaments to solidify into upstream linear bridging filaments that are bonded to the upstream pleat tips of the fibrous air-filtration web.