Filtration Medias, Fine Fibers Under 100 Nanometers, and Methods

a technology of fine fibers and filtration media, applied in the field of polymeric fine fibers, can solve the problems of unfavorable change of filtration characteristics, and achieve the effect of preventing sufficient delamination of the fine fiber layer

Inactive Publication Date: 2009-08-13
ELMARCO SRO
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0008]Preferably, solvent bonding is provided between the substrate layer and the fine fiber layer to prevent delamination of the fine fiber layer sufficient for use in filtration applications.

Problems solved by technology

Such delamination or loss of part of the fine fiber layer can undesirably change filtration characteristics.

Method used

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  • Filtration Medias, Fine Fibers Under 100 Nanometers, and Methods
  • Filtration Medias, Fine Fibers Under 100 Nanometers, and Methods
  • Filtration Medias, Fine Fibers Under 100 Nanometers, and Methods

Examples

Experimental program
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Effect test

example 1

[0158]Tests were performed on of a commercially available filter media composite product Donaldson Company, Inc., Minneapolis, Minn. Considering the media was contained in a cartridge, filter media samples were carefully removed from a cartridge for testing. Observations showed that the filter media composite included a coarser filter media substrate material and a layer of fine fibers deposited thereon. As shown in the scanning electron-microscope image of FIG. 18, fiber diameter of the fine fibers in the fine fiber layer was observed to typically greater than 100 nanometers and there was not a significant amount of fine fibers with diameters of less than 100 nanometers.

[0159]The composite media included a basis weight of 71.03 lb / 3000 ft2; a Frazier Permeability of 13.5 (CFM @ 0.5″ WG); and a caliper thickness of 0.3 mil. Testing results indicated that the filter media could qualify as MERV 14 (based on fractional efficiency data), with an initial pressure drop of 362.87 Pa.

[0160]...

example 2

[0161]Tests were performed on the substrate filter media of example 1 for purposes of attempting to better evaluate the filtration characteristics of the fine fiber layer. Specifically, samples of the commercially available filter media composite product Donaldson Company, Inc., Minneapolis, Minn. were first soaked in isopropyl alcohol to dissolve and thereby remove the fine fiber layer. The fine fibers appeared to completely dissolve in isopropyl alcohol, which is why isopropyl alcohol was chosen as the solvent. The samples were then allowed to dry to evaporate the isopropyl solvent and then the samples were tested.

[0162]The substrate media included a basis weight of 71.27 lb / 3000 ft2; a Frazier Permeability of 15.3 (CFM @ 0.5″ WG); and a caliper thickness of 0.3 mil. Testing results indicated that the filter media could qualify as MERV 13 (based on fractional efficiency data), with an initial pressure drop of 378.13 Pa.

[0163]Pore size and fractional efficiency test data for Exampl...

example 3

[0164]Tests were performed on an uncoated, relatively low grade cellulose fiber material substrate filter media that was used as the substrate material for the fine fiber filter media composite of Example 4. The substrate filter media was purchased from Ahlstrom of under the brand / model designation AFI-23N-4. Thus, there was no need to prepare the sample through an isopropyl alcohol soak as was done for Example 2.

[0165]The substrate media included a basis weight of 59.8 lb / 3000 ft2; a Frazier Permeability of 23.4 (CFM @ 0.5″ WG); and a caliper thickness of 0.4 mil. Testing results indicated that the filter media could qualify as MERV 12 (based on fractional efficiency data), with an initial pressure drop of 242.63 Pa.

[0166]Pore size and fractional efficiency test data for Example 3 were as follows and / or are shown in FIGS. 14 and 16:

TABLE 8Pore size (μm)Test Number123MeanSDMax40.639.242.640.811.68Mean12.012.212.012.0730.13Smallest2.522.472.382.45670.07

TABLE 9Cumulative Filter Flow, ...

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Abstract

An electrospinning fine fiber production methodology for generating a significant amount of fibers with diameters of less than 100 nanometers is provided. Also, a filter media composite comprising a substrate layer and an electrospun fine fiber layer having a increased efficiency relative to pressure drop and / or a controlled pore size distribution is provided. According to some embodiments nylon is electrospun from a solvent combination of formic and acetic acids.

Description

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS[0001]This patent application claims the benefit of U.S. Provisional Patent Application No. 60 / 989,218, the entire teachings and disclosure of which are incorporated herein by reference thereto.FIELD OF THE INVENTION[0002]The present invention generally relates to polymeric fine fibers such as may be made from electrostatic spinning of fibers from a polymeric solution, methods involving the same and / or new filter media composite structures incorporating fine fibers.BACKGROUND OF THE INVENTION[0003]The production of fine fibers from polymeric solution through electrostatic spinning (a.k.a. “electro-spinning”) via an electric field created by a voltage differential between a collecting electrode and a spinning electrode is known. For example, as shown in U.S. Pat. No. 6,743,273, polymeric solution is pumped to a spinning electrode in the form of a rotating emitter in which the pump solution is pumped from a reservoir and forced through hol...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): B01D53/22D04H1/4334D04H1/4374D04H1/728
CPCB01D39/1623B01D2239/025Y10S977/762B82Y30/00B01D39/04
Inventor GREEN, THOMAS B.KING, SCOTTY L.LI, LEI
Owner ELMARCO SRO
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