Composite filter media
A composite filter media having excellent dust-releasing properties provided with a layer of netting formed of a low surface free energy material that is hot calendered to the upstream surface of a supporting layer formed of non-woven synthetic fibers. A filtering layer formed of non-woven synthetic fibers is laminated to the downstream surface of the supporting layer. The filtering layer may include an electrostatic charge to increase filter efficiency at a reduced pressure drop across the composite media.
1. A composite air filter media comprising, in combination:
a. at least one layer of gas-permeable supportive material formed from a plurality of bonded fibers, the supportive layer having an upstream surface and a downstream surface;
b. a layer of netting formed of low surface free energy material bonded to the upstream surface of said at least one layer of gas-permeable supportive material, thereby forming a particulate-releasing surface for receiving particulate matter initially impacting the composite air filter media and subsequently releasing at least a significant portion of the particulate matter from the composite air filter media, wherein the thickness of the netting is in a range of about 75 micrometers to about 250 micrometers; and
c. at least one layer of gas-permeable filtration material formed from a plurality of bonded fibers, the filtration layer bonded to the downstream surface of said at least one layer of supportive material.
2. The composite air filter in accordance with claim 1 , wherein said at least one layer of gas-permeable supportive material is formed of nonwoven synthetic fibers.
3. The composite air filter in accordance with claim 2 , wherein said at least one layer of gas-permeable supportive material is manufactured using a process taken from the group consisting of air laid, wet laid, spunbond and meltblown.
4. The composite air filter in accordance with claim 1 , wherein the netting is laminated to the supportive layer by a hot calendering process.
5. The composite air filter in accordance with claim 1 , wherein the netting is formed of polyolefin.
6. The composite air filter in accordance with claim 5 , wherein the netting is formed of polypropylene.
7. The composite air filter in accordance with claim 5 , wherein the netting is formed of high density polyethylene.
8. The composite air filter in accordance with claim 5 , wherein the netting includes fluorochemical additives.
9. The composite air filter in accordance with claim 1 , wherein the netting is treated with a hydrophobic material for enhancing the dust-releasing properties of the netting.
10. The composite air filter in accordance with claim 1 , wherein the netting has an open area in a range of about 25% to about 75% of the total area of the netting.
11. The composite air filter in accordance with claim 10 , wherein the netting has an open area in a range of about 40% to about 60% of the total area of the netting.
12. The composite air filter in accordance with claim 1 , wherein the thickness of the netting is in a range of about 100 micrometers to about 150 micrometers.
13. The composite air filter in accordance with claim 1 , wherein the basis weight of the netting is in a range of about 10 grams per square meter to about 30 grams per square meter.
14. The composite air filter in accordance with claim 1 , wherein said layer of filter material is formed of nonwoven synthetic fibers.
15. The composite air filter in accordance with claim 14 , wherein said layer of filter material comprises melt-blown synthetic fibers taken from the group consisting of polypropylene, polyester and nylon.
16. The composite air filter in accordance with claim 15 , wherein said at least one layer of filter material is electrostatically charged.
17. A composite air filter media comprising, in combination:
a. at least one layer of gas-permeable filter material formed from a plurality of bonded fibers, the filter layer having an upstream surface and a downstream surface;
b. a first layer of netting formed of low surface free energy material that is bonded to the upstream surface of said at least one layer of filter material, thereby forming a particulate-releasing surface for receiving particulate matter initially impacting the composite air filter media and subsequently releasing at least a significant portion of the particulate matter from the composite air filter media; and
c. a second layer of netting formed of low surface free energy material that is laminated to the downstream surface of said at least one layer of filter material;
wherein the thickness of each layer of netting is in a range of about 75 micrometers to about 250 micrometers.
18. The composite air filter in accordance with claim 17 , wherein said at least one layer of gas-permeable filter material comprises melt-blown synthetic fibers taken from the group consisting of polypropylene, polyester and nylon.
19. The composite air filter in accordance with claim 17 , wherein at least one of the layers of netting is formed of polypropylene.
20. The composite air filter in accordance with claim 17 , wherein at least one of the layers of netting is formed of high density polyethylene.
21. The composite air filter in accordance with claim 17 , wherein at least one layer of gas-permeable supportive material is laminated between said at least one layer of gas-permeable filter material and at least one of the layers of netting.
22. The composite air filter in accordance with claim 21 , wherein said at least one layer of gas-permeable supportive material is formed of nonwoven synthetic fibers.
23. The composite air filter in accordance with claim 22 , wherein said at least one layer of gas-permeable supportive material is manufactured using a process taken from the group consisting of air laid, wet laid, spunbond and meltblown.
24. The composite air filter in accordance with claim 17 , wherein said at least one layer of filter material is electrostatically charged.
25. The composite air filter in accordance with claim 17 , wherein at least one of the layers of netting includes a dye that colors the layer of netting.
26. The composite air filter in accordance with claim 17 , wherein at least one of the layers of netting includes an antimicrobial agent.
27. The composite air filter in accordance with claim 17 , wherein at least one of the layers of netting includes a scented additive.
28. A method of forming a composite air filter media, the method comprising:
a. forming a gas-permeable supportive layer from a plurality of bonded fibers, the supportive layer having an upstream surface and a downstream surface;
b. bonding a netting formed of a low surface free energy material to the upstream surface of the supportive layer, thereby forming a particulate-releasing surface for receiving particulate matter initially impacting the composite air filter media and subsequently releasing at least a significant portion of the particulate matter from the composite air filter media, wherein the thickness of the netting is in a range of about 75 micrometers to about 250 micrometers; and
c. bonding at least one layer of a gas-permeable filtration material to the downstream surface of said at least one layer of supportive material, the filtration layer formed from a plurality of bonded fibers.
29. The method in accordance with claim 28 , wherein the step of bonding further comprises hot calendering the supportive layer to the netting layer, thereby forming the particulate-releasing upstream surface on the netting.