Non-woven filter composite

• US 5,582,865 A
• Filed: 01/12/1994
• Issued: 12/10/1996
• Est. Priority Date: 12/12/1988
• Status: Expired due to Term

• Current Assignee: Entegris Incorporated
• Original Assignee: Extraction Systems, Inc. (Entegris Incorporated)
• Inventors: Kinkead, Devon A., Rezuke, Robert W.
• Primary Examiner(s): DUDASH, DIANA L
• Application Number:
  US08/180,529
• Time in Patent Office: 1,063 Days
• Field of Search: 427/244, 427/366, 427/346, 427/180, 427/557, 427/559, 427/185, 427/184, 427/374.4
• US Class Current: 427/244
• CPC Class Codes: A61L 9/046 with the help of a non-organic compound
• CPC Class Codes: A62B 23/025 the filter having substantially the shape of a mask surgical face masks A41D13/11
• CPC Class Codes: B01D 2239/0407 comprising particulate additives, e.g. adsorbents apparatus incorporating gas filtering material B01D46/0036
• CPC Class Codes: B01D 2239/0464 Impregnants
• CPC Class Codes: B01D 2239/065 More than one layer present in the filtering material apparatus incorporating such gas filtering material B01D2275/10
• CPC Class Codes: B01D 2239/0695 Wound layers apparatus incorporating such gas filtering material B01D2275/105
• CPC Class Codes: B01D 39/08 Filter cloth, i.e. woven, knitted or interlaced material metallic B01D39/10
• CPC Class Codes: B01D 39/1623 of synthetic origin
• CPC Class Codes: B01D 46/12 in multiple arrangements
• CPC Class Codes: B01D 53/46 Removing components of defined structure
• CPC Class Codes: B01J 20/28028 Particles immobilised within fibres or filaments
• CPC Class Codes: B32B 2262/0276 Polyester fibres
• CPC Class Codes: B32B 2307/724 Permeability to gases, adsorption
• CPC Class Codes: B32B 5/022 Non-woven fabric
• CPC Class Codes: B32B 5/26 another layer next to it also being fibrous or filamentary relative arrangement of fibres or filaments of different layers B32B5/12
• CPC Class Codes: B32B 7/02 Physical, chemical or physicochemical properties
• CPC Class Codes: F24F 3/167 Clean rooms, i.e. enclosed spaces in which a uniform flow of filtered air is distributed air distribution by perforated walls F24F7/10

Abstract

A method of making a high efficiency, low pressure drop, adsorptive, non-woven filter composite is disclosed, comprising a high surface area chemically impregnated adsorbent, and a non-woven carrier material; and a method for forming said composite comprising dry application of the chemically impregnated adsorbent to the non-woven carrier material which is then heated and calendared with or without a cover sheet.

Claims

1. A method for forming a vapor absorptive non-woven air filter composite comprising thermo-plastic fibers and adsorptive particles, said composite having a given fiber density, comprising the steps of:

providing a non-woven carrier material having a substantially flat top surface and comprising thermo-plastic fibers of lower fiber density relative to the fiber density of the resultant composite;

under dry conditions, applying adsorbent particles of a range of particle sizes to said top surface of said carrier material,

agitating said carrier material until the adsorbent particles penetrate the top surface of the carrier material and become distributed throughout the depth of said carrier material;

thereafter heating said carrier material and applied adsorbent particles; and

calendering the heated carrier material with said adsorbent particles distributed therethrough;

wherein said heating and calendering steps are performed for a period of time and under a pressure selected to be sufficient for said adsorbent particles to become retained within said heated and calendered carrier material to form a calendered composite having an open fibrous structure of said given fiber density with the surfaces of said distributed adsorbent particles being substantially exposed for contact with air passing through said calendered composite, said resulting non-woven air filter composite being characterized by a pressure drop sufficient for use as an air filter.

3. The method of claim 1 or 2, further comprising the step of applying a wire mesh to the carrier material prior to said calendering step.

4. The method of claim 3, further comprising the step of embossing said carrier material after said calendering step.

5. The method of claim 4, further comprising the step of pleating said carrier material after said embossing step.

6. The method of claim 1 or 2 wherein said non-woven carrier material comprises a non-woven batting having a non-woven top layer surface attached to a relatively higher fiber density non-woven backing layer.

7. The method of claim 1 or 2 wherein said adsorbent particles are chemically impregnated carbon particles.

8. The method of claim 7 wherein said carbon particles are impregnated with chemicals selected from the group consisting of copper chloride, iodine, bromine, transition metal oxides and salts thereof, sodium carbonate, sodium chromate, triethylenediamine, tromethamine, potassium hydroxide and potassium iodide.

9. The method of claim 1 or 2 wherein said adsorbent particles are ion exchange resins.

10. The method of claim 1 or 2, wherein said calendering step includes using at least one calender roll which is temperature controlled.

11. The method of claim 1 or 2 wherein said adsorbent particles are non-impregnated activated carbon particles.

12. The method of claim 1 or 2 wherein said range of particle sizes lies between about 20 and 140 mesh.

13. The method of claim 1 or 2 wherein said step of agitating said carrier material comprises agitating said carrier material in a direction which is both perpendicular to the direction of travel of the carrier material and along said substantially flat surface of said carrier material.

14. The method of claim 1 or 2 further comprising the step of applying a cover sheet to said open surface of the carrier material.

15. The method of claim 14 further comprising the step of applying a second cover sheet to a second surface of said carrier material, said second surface being opposite said open surface.

16. The method of claim 1 or 2 wherein said step of applying adsorbent particles comprises the step of fluidizing said adsorbent particles on a vibrator tray.

17. The method of claim 16 further comprising the step of spilling said adsorbent particles from said vibrator tray into a roller system from which said particles fall onto said carrier material.

19. The method of claim 1 or 2 wherein the resulting air filter composite that is formed has a thickness of about 0.8 inches.

21. The method of claim 6 wherein said top layer is thicker along the depth dimension of said carrier material than said backing layer.

22. The method of claim 6 wherein said backing layer comprises a needle-punched layer.

23. The method of claim 13 wherein said carrier material is agitated using a roll bar.

25. The method of claim 1 or 2 wherein the thermoplastic fibers of said non-woven carrier material are of uniform material composition.

26. The method of claim 1 or 2 wherein said calendering step is carried out at a calendering pressure of 3000-5000 psi.

2. A method for forming a vapor adsorptive non-woven air filter composite comprising thermo-plastic fibers and adsorptive particles, said composite having a given fiber density, comprising the steps of:

providing a non-woven carrier material having a substantially flat top surface and comprising thermo-plastic fibers of lower fiber density relative to the fiber density of the resultant composite;

under dry conditions, applying adsorbent particles of a range of particle sizes to said top surface of said carrier material;

agitating said carrier material until the adsorbent particles penetrate the top surface of the carrier material and become distributed through the depth of said carrier material;

heating said carrier material to a temperature below the melting point of the fibers of said carrier material; and

calendering the heated carrier material with said adsorbent particles distributed therethrough;

wherein said calendering step is performed under a pressure selected to be sufficient for said adsorbent particles to become retained within said heated and calendered carrier material to form a calendered composite having an open fibrous structure of said given fiber density with the surfaces of said distributed adsorbent particles being substantially exposed for contact with air passing through said calendered composite, said resulting non-woven air filter composite being characterized by a pressure drop sufficient for use as an air filter.

18. The method of claim 2 wherein the non-woven carrier material that is provided comprises polyester fibers.

20. The method of claim 2 wherein said heating step is performed after said applying and agitating steps.

24. The method of claim 2 wherein said thermo-plastic fibers are formed of polyester and during said heating step said polyester fibers are heated to a temperature in the range of 250°

-350°

F.