US4734208A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Charge-modified microfiber filter sheets
Assignee: Pall Corp
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Filing: 1985-03-28
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Granted: 1988-03-29
•
Expires: 2005-03-28
Abstract
Abstract Filter media comprised of charge modified, resin coated inorganic microfibers are prepared by mixing inorganic microfibers with an aqueous solution of a water soluble, noncolloidal cationic thermosetting binder resin to form a dispersion, following which a precipitating agent is added to precipitate the binder resin and coat the microfibers. The coated microfibers may be used in the dispersed or suspended form as a filter aid. Preferably they are formed into a filter sheet which is then dried and cured to form a filter sheet of narrowly distributed pore size, pore sizes as small as one-half micron, and having a positive zeta potential in alkaline media. Glass is the preferred microfiber and polyamine-epichlorohydrins the preferred resins. By providing the normally negative zeta potential microfibers with a positive zeta potential the binder resins used to coat the microfibers substantially enhance particulate removal capabilities of the microfiber filter sheet.
Inventors
- 👤 David B. Pall
- 👤 Peter J. Degen
- 👤 Irving B. Joffee
- 👤 Warren M. Foss
- 👤 Thomas C. Gsell
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 01:15
CPC Classifications
B; B01; B01D; B01D39/00; B01D39/14; B01D39/20; B01D39/2003; B01D39/2017; B01D39/2024; B01D2239/00; B01D2239/04; B01D2239/0471
Claims Analysis
Total Claims: 28
Claim 1
Independent Claim
79 words
A filter sheet exhibiting a positive zeta potential over a pH range of from about 3 to about 10 comprising: a mat of inorganic microfibers normally having a negative zeta potential substantially uniformly coated with a cured, precipitated cationic thermosetting binder resin or polymer, said binder resin or polymer being present in an amount sufficient to impart said positive zeta potential to said filter sheet and to bond said microfibers together thereby imparting tensile strength to said filter sheet.
Claim 2
Dependent Claim
79 words
A filter sheet exhibiting a positive zeta potential over a pH range of from about 3 to about 10 comprising: a mat of inorganic microfibers normally having a negative zeta potential substantially uniformly coated with a cured, precipitated cationic thermosetting binder resin or polymer, said binder resin or polymer being present in an amount sufficient to impart said positive zeta potential to said filter sheet and to bond said microfibers together thereby imparting tensile strength to said filter sheet.
Claim 3
Dependent Claim
22 words
The filter sheet of claim 1 wherein said microfibers are selected from the group comprising glass microfibers, titanate microfibers, and mixtures thereof.
Claim 4
Dependent Claim
25 words
The filter sheet of claim 1 wherein said binder resin or polymer is selected from the group comprising epoxide-based resins, polyamido/polyamino-epichlorohydrin resins, and polyamine-epichlorohydrin resins.
Claim 5
Dependent Claim
30 words
The filter sheet of claim 1 wherein the weight ratio of said binder resin or polymer to said microfibers is in the range of from about 1:100 to about 40:100.
Claim 6
Dependent Claim
26 words
The filter sheet of claim 4 wherein the weight ratio of said binder resin or polymer to said microfibers is from about 5:100 to about 30:100.
Claim 7
Dependent Claim
22 words
The filter sheet of claim 1 wherein said filter sheet has actual pore sizes ranging from about 0.5 to about 50 micrometers.
Claim 8
Dependent Claim
21 words
The filter sheet of claim 1 wherein said filter sheet has a minimum tensile strength of about 0.4 pounds per inch.
Claim 9
Dependent Claim
24 words
The filter sheet of claim 7 wherein said filter sheet has a tensile strength of from about 0.4 to about 3 pounds per inch.
Claim 10
Dependent Claim
28 words
The filter sheet of claim 1 wherein said microfibers are staple fibers and have a mean diameter in the range of from about 0.1 to about 10 micrometers.
Claim 11
Dependent Claim
20 words
The filter sheet of claim 1 wherein the maximum pore size of said filter sheet is 20 micrometers or less.
Claim 12
Dependent Claim
11 words
The filter sheet of claim 1 further comprising a porous backing.
Claim 13
Dependent Claim
22 words
A method for the filtration of particulates from a fluid medium comprising passing said medium through the filter sheet of claim 1.
Claim 14
Dependent Claim
73 words
A filter sheet exhibiting a positive zeta potential in alkaline media consisting essentially of: a mat of inorganic microfibers normally having a negative zeta potential substantially uniformly coated with a cured, precipitated, cationic thermosetting binder resin or polymer, said binder resin or polymer being present in an amount sufficient to impart said positive zeta potential to said filter sheet and to bond said microfibers together, thereby imparting tensile strength to said filter sheet.
Claim 15
Dependent Claim
73 words
A filter sheet exhibiting a positive zeta potential in alkaline media consisting essentially of: a mat of inorganic microfibers normally having a negative zeta potential substantially uniformly coated with a cured, precipitated, cationic thermosetting binder resin or polymer, said binder resin or polymer being present in an amount sufficient to impart said positive zeta potential to said filter sheet and to bond said microfibers together, thereby imparting tensile strength to said filter sheet.
Claim 16
Dependent Claim
22 words
The filter sheet of claim 13 wherein said microfibers are selected from the group comprising glass microfibers, titanate microfibers, and mixtures thereof.
Claim 17
Dependent Claim
25 words
The filter sheet of claim 13 wherein said binder resin or polymer is selected from the group comprising epoxide-based resins, polyamido/polyamino-epichlorohydrin resins, and polyamine-epichlorohydrin resins.
Claim 18
Dependent Claim
30 words
The filter sheet of claim 13 wherein the weight ratio of said binder resin or polymer to said microfibers is in the range of from about 1:100 to about 40:100.
Claim 19
Dependent Claim
26 words
The filter sheet of claim 1 wherein the weight ratio of said binder resin or polymer to said microfibers is from about 5:100 to about 30:100.
Claim 20
Dependent Claim
22 words
The filter sheet of claim 13 wherein said filter sheet has actual pore sizes ranging from about 0.5 to about 50 micrometers.
Claim 21
Dependent Claim
21 words
The filter sheet of claim 13 wherein said filter sheet has a minimum tensile strength of about 0.4 pounds per inch.
Claim 22
Dependent Claim
24 words
The filter sheet of claim 13 wherein said filter sheet has a tensile strength of from about 0.4 to about 3 pounds per inch.
Claim 23
Dependent Claim
28 words
The filter sheet of claim 13 wherein said microfibers are staple fibers and have a mean diameter in the range of from about 0.1 to about 10 micrometers.
Claim 24
Dependent Claim
20 words
The filter sheet of claim 13 wherein the maximum pore size of said filter sheet is 20 micrometers or less.
Claim 25
Dependent Claim
11 words
The filter sheet of claim 13 further comprising a porous backing.
Claim 26
Dependent Claim
22 words
A method for the filtration of particulates from a fluid medium comprising passing said medium through the filter sheet of claim 13.
Claim 27
Dependent Claim
19 words
The filter sheet of claim 11 wherein said porous backing is intimately adhered to said mat of inorganic microfibers.
Claim 28
Dependent Claim
19 words
The filter sheet of claim 23 wherein said porous backing is intimately adhered to said mat of inorganic microfibers.
References Cited (Backward Citations)
US4617128A
Cited
US4645567A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-03-29 | 1991-09-28 | 1992-03-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-03-29 | 1995-09-28 | 1996-03-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-03-29 | 1999-09-28 | 2000-03-29 | $7700.00 | Window Closed / Lapsed |