High efficiency active electrostatic air filter and method of manufacture

DETAILED DESCRIPTION OF THE INVENTION The active electrostatic filter contains a core layer of a bendable material, from 0.
05 to 0.
45 inches in thickness selected from polymeric foam or a high loft fibrous polymeric material such as air laid polyester fibers having a density of from 0.
5 to 5 ounces per square yard (OPSY).
The fibers are resin bonded by a resin such as an acrylic resin or point bonded or needle, bonded.
In a preferred embodiment the central or core layer is comprised of a thermoset material.
This material removes most of the particles from the air stream, typically at least 80% of the incoming particles having sizes up to 10 microns.
The particle capture efficiency of the core material is enhanced by placing a layer of passive or active electrostatic polymer material on each side of the core material.
The material can be woven or non woven.
Passive electrostatic materials are used which become charged as air flows past the polymers that tend to have natural static charges.
Active electrostatic materials contain charge control agents.
These are preferred since the available active electrostatic fibrous materials produce an undesirably high-pressure drop as a filtration media and are not cleanable.
The material is usually formed by casting, extrusion or weaving from a polymer of a nonsaturated alkene monomer having 2-8 carbon atoms.
One type of material is woven polypropylene netting having a thickness from 0.
01 to 0.
10 inches, usually from 0.
02 to 0.
06 inches.
The yarn diameter can be from 1-35 denier, preferably from 5-20 denier.
The ratio of warp to fill yarn is from 1.
2/1 to 3/1 and the netting is woven in a manner to resemble a honeycomb structure.
A commercially available material is a honeycomb weave netting of 8 mil thick polypropylene fibers available in thicknesses of 0.
03 and 0.
05 inches.
The yarn count is 51 warp and 32 fill.
The outside grill layer does not contribute to filtering but is present to hold the angled media after it has been formed.
Again, the layer must be capable of being easily bent or deformed during the assembly process