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Filter media with charge stabilizing and enhancing additives

a filter media and additive technology, applied in the field of electrostatic filter media, can solve the problems of loss of charge or its spatial orientation, and the charge pairs or dipoles of conventional filter media are often not stable,

Inactive Publication Date: 2006-04-13
HOLLINGSWORTH VOSE
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

"The present invention provides a new technology that improves the efficiency of a heat exchanger. This technology involves using a special coating on the heat exchanger that helps to reduce the amount of fouling that occurs during operation. This coating also helps to prevent the growth of certain types of bacteria and other living organisms that can damage the heat exchanger. Overall, this technology makes the heat exchanger last longer and work better."

Problems solved by technology

Conventional filter media are substantially lacking in electrostatic charge and rely upon impingement, impaction and diffusion for filter performance.
One problem associated with electret filter material is that the charge pairs or dipoles imparted to the filter media often are not stable.
In some instances, charge or its spatial orientation is lost after filtering certain contaminants for relatively short time periods.
The result is a marked decrease in filter performance over a relatively short period of time (e.g., less than 20 minutes).
One other problem associated with electret filter material is their inability to maintain the electrostatic charge after being subjected to heat.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

example 1

[0031] Sample 1-1 of a meltblown electret polymer fiber web was prepared, as previously described, from a composition containing 99% by weight of polypropylene and 1% by weight of ACRAWAX™ C. The meltblown electret polymer fiber web was prepared with fibers having a diameter of 3.6μ, and a web basis weight of 23.69 g / m2.

[0032] Sample 1-2 of a meltblown electret polymer fiber web was prepared, as previously described, from a composition containing 99.6% by weight of polypropylene and 0.4% by weight of magnesium stearate. The meltblown electret polymer fiber web was prepared with fibers having a diameter of 3.51μ, and a web basis weight of 22.25 g / m2.

[0033] Sample 1-3 of a meltblown electret polymer fiber web was prepared, as previously described, from a composition containing 98.6% by weight of polypropylene, 1% by weight of ACRAWAX™ C, and 0.4% by weight of magnesium stearate. The meltblown electret polymer fiber web was prepared with fibers having a diameter of 8μ, and a web basi...

example 2

[0037] Sample 2-1 of a meltblown electret polymer fiber web was prepared, as previously described, from a composition containing 99% by weight of polypropylene and 1% by weight of ACRAWAX™ C. The meltblown electret polymer fiber web was prepared with fibers having a diameter of 6.8μ, and a web basis weight of 60.4 g / m2.

[0038] Sample 2-2 of a meltblown electret polymer fiber web was prepared, as previously described, from a composition containing 99.6% by weight of polypropylene and 0.4% by weight of magnesium stearate. The meltblown electret polymer fiber web was prepared with fibers having a diameter of 7.4μ, and a web basis weight of 60.04 g / m2.

[0039] Sample 2-3 of a meltblown electret polymer fiber web was prepared, as previously described, from a composition containing 98.6% by weight of polypropylene, 1% by weight of ACRAWAX™ C, and 0.4% by weight of magnesium stearate. The meltblown electret polymer fiber web was prepared with fibers having a diameter of 3.4μ, and a web basi...

example 3

[0042] Sample 3-1 of a meltblown electret polymer fiber web was prepared, as previously described, from a composition containing 99% by weight of polypropylene and 1% by weight of ACRAWAX™ C. The meltblown electret polymer fiber web was prepared with fibers having a diameter of 7.8%, and a web basis weight of 22.43 g / m2.

[0043] Sample 3-2 of a meltblown electret polymer fiber web was prepared, as previously described, from a composition containing 99.6% by weight of polypropylene and 0.4% by weight of zinc stearate. The meltblown electret polymer fiber web was prepared with fibers having a diameter of 7.4μ, and a web basis weight of 22 g / m2.

[0044] Sample 3-3 of a meltblown electret polymer fiber web was prepared, as previously described, from a composition containing 98.6% by weight of polypropylene, 1% by weight of ACRAWAX™ C, and 0.4% by weight of zinc stearate. The meltblown electret polymer fiber web was prepared with fibers having a diameter of 3.4μ, and a web basis weight of ...

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Abstract

Electret filter media having an increased electrostatic charge that is substantially maintained in the presence of heat are provided. In one exemplary embodiment, the filter media includes a melt processable charge enhancing additive, such as a fatty acid amide, and a melt processable charge stabilizing additive, such as a fatty acid metal salt. The charge enhancing additive is particularly effective to increase or enhance the electrostatic charge of the filter media when a charge is imparted thereto, and the charge stabilizing additive is particularly effective to stabilize the charge such that, when the filter media is subjected to a heat treatment, the enhanced electrostatic charge is substantially maintained.

Description

FIELD OF THE INVENTION [0001] The present invention relates to electret filter media having an increased level of electrostatic charge that is substantially maintained in the presence of heat. BACKGROUND OF THE INVENTION [0002] Electret filter media have long been used in many filtration applications. Electret filter media are those that include a dielectric insulating polymer web that is treated to possess substantially permanent spatially oriented, opposite charge pairs or dipoles. Among the common polymer webs used for electret filter media are polypropylene, polyethylene, polyester, polyamide, polyvinyl chloride, and polymethyl methylacrylate. [0003] Conventional filter media are substantially lacking in electrostatic charge and rely upon impingement, impaction and diffusion for filter performance. Electret filter materials offer improved filtering performance over conventional filter materials. The presence of oriented dipoles in the electret filter media is believed to enhance...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): D04H1/00D02G1/20D04H1/56
CPCB01D39/1623Y10T442/69Y10T442/68Y10T442/696
Inventor COX, STEPHEN T.
Owner HOLLINGSWORTH VOSE