US4617124A
Expired / Lapsed
US
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Polymeric microfibrous filter sheet, preparation and use
Assignee: Pall Corp
•
Filing: 1982-07-13
•
Granted: 1986-10-14
•
Expires: 2002-07-13
Abstract
Abstract Microfibrous, polymeric filter sheets and filter elements prepared therefrom comprised of a normally hydrophobic, microfibrous, polymeric web, wherein the surfaces of the microfibers making up the web are coated with a cured, precipitated, cationic, thermosetting binder resin or polymer. The filter sheet is further characterized by being hydrophilic and having a positive zeta potential. The process for preparing such filter sheets comprises four steps: (1) applying a first solution or dispersion of a precipitating agent to a hydrophobic web to at least partially wet the web; (2) applying a second solution of the binder resin or polymer to the wetted web of step (1); (3) working the wetted web of step (2) to mix the first and second solutions, thereby facilitating the precipitation of the binder resin or polymer and the distribution of the precipitated binder resin or polymer as a coating on the surface of the microfibers making up the worked web; and (4) drying and curing the coated web of step (3) to form the desired filter sheets. The filter sheets have enhanced mechanical strength, are hydrophilic, have positive zeta potentials over the pH range of from about 3 to about 10 and typically have absolute pore ratings of from about 0.5 to about 80 micrometers.
Inventors
- 👤 David B. Pall
- 👤 Peter J. Degen
- 👤 Thomas C. Gsell
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 20:18
CPC Classifications
C; C02; C02F; C02F1/00; C02F1/28; C02F1/285; A; A61; A61L; A61L2/00; A61L2/02; A61L2/022; B; B01; B01D; B01D39/00; B01D39/14; B01D39/16; B01D39/1607; B01D39/1623; B01D39/163; B01D2239/00; B01D2239/04; B01D2239/0414; B01D2239/0421; B01D2239/0471; B01D2239/08; B01D2239/10; B01D2239/12; B01D2239/1216; B01D2239/1233; B01D2239/1291
Claims Analysis
Total Claims: 99
Claim 1
Independent Claim
194 words
A process for converting a hydrophobic web comprised of polymeric microfibers to a hydrophilic, microfibrous, polymeric filter sheet exhibiting a positive zeta potential comprising: (1) applying a first solution or dispersion of a precipitating agent to said web to at least partially wet said web with said first solution or dispersion; (2) applying a second solution of a water-soluble, non-colloidal, cationic, thermosetting binder resin or polymer to the wetted web of step (1) above to form a web wetted with a mixture of said first solution or dispersion and said second solution; (3) working the wetted web of step (2) above to mix said first solution or dispersion and said second solution thereby facilitating the precipitation of said binder resin or polymer and the distribution thereof as a coating on the surfaces of the microfibers of the worked web; and (4) drying the coated web of step (3) above and curing the precipitated binder resin or polymer to provide a hydrophilic, microfibrous, polymeric filter sheet with a positive zeta potential and which is further characterized by the surfaces of the microfibers therein being coated with a cured, precipitated, thermoset, cationic binder resin or polymer.
Claim 2
Dependent Claim
194 words
A process for converting a hydrophobic web comprised of polymeric microfibers to a hydrophilic, microfibrous, polymeric filter sheet exhibiting a positive zeta potential comprising: (1) applying a first solution or dispersion of a precipitating agent to said web to at least partially wet said web with said first solution or dispersion; (2) applying a second solution of a water-soluble, non-colloidal, cationic, thermosetting binder resin or polymer to the wetted web of step (1) above to form a web wetted with a mixture of said first solution or dispersion and said second solution; (3) working the wetted web of step (2) above to mix said first solution or dispersion and said second solution thereby facilitating the precipitation of said binder resin or polymer and the distribution thereof as a coating on the surfaces of the microfibers of the worked web; and (4) drying the coated web of step (3) above and curing the precipitated binder resin or polymer to provide a hydrophilic, microfibrous, polymeric filter sheet with a positive zeta potential and which is further characterized by the surfaces of the microfibers therein being coated with a cured, precipitated, thermoset, cationic binder resin or polymer.
Claim 3
Dependent Claim
43 words
The process of claim 1 wherein said working of the wetted web of step (2) is carried out by contacting said wetted web with a roller rotating counter to the direction said wetted web is moving as the web moves past said roller.
Claim 4
Dependent Claim
18 words
The process of claim 2 wherein steps (1), (2) and (3) are carried out in a continuous manner.
Claim 5
Dependent Claim
47 words
The process of claim 3 wherein in step (1) said web is saturated with said first solution or dispersion following which a portion of said first solution or dispersion is removed from said wetted web of step (1) prior to applying said second solution in step (2).
Claim 6
Dependent Claim
40 words
The process of claim 1 wherein said drying and said curing in step (4) are carried out at an elevated temperature of from about 50 to about 150 degrees Centigrade for a period of from several minutes to several days.
Claim 7
Dependent Claim
41 words
The process of claim 5 wherein said drying and said curing in step (4) are carried out at an elevated temperature of from about 75 to about 130 degrees Centigrade for a period of from about 5 to about 60 minutes.
Claim 8
Dependent Claim
41 words
The process of claim 1 wherein said polymeric microfibers of said hydrophobic web are comprised of a polyolefin and said hydrophobic web is prewet with a wetting solution comprising water and a wetting agent prior to step (1) of claim 1.
Claim 9
Dependent Claim
10 words
The process of claim 7 wherein said polyolefin is polypropylene.
Claim 10
Dependent Claim
18 words
The process of claim 1 wherein said polymeric microfibers of said hydrophobic web are comprised of a polyamide.
Claim 11
Dependent Claim
11 words
The process of claim 9 wherein said polyamide is nylon 66.
Claim 12
Dependent Claim
11 words
The process of claim 9 wherein said polyamide is nylon 11.
Claim 13
Dependent Claim
18 words
The process of claim 1 wherein said polymeric microfibers of said hydrophobic web are comprised of a polyester.
Claim 14
Dependent Claim
11 words
The process of claim 12 wherein said polyester is polyethylene terephthalate.
Claim 15
Dependent Claim
11 words
The process of claim 12 wherein said polyester is polybutylene terephthalate.
Claim 16
Dependent Claim
39 words
The process of claim 1 wherein said hydrophobic web is comprised of microfibers having diameters of from about 0.5 to about 20 micrometers and said hydrophobic web has absolute pore ratings of from about 0.5 to about 80 micrometers.
Claim 17
Dependent Claim
35 words
The process of claim 15 wherein said microfibers have diameters of from about 1.0 to about 10 micrometers and said hydrophobic web has an absolute pore rating of from about 0.6 to about 10 micrometers.
Claim 18
Dependent Claim
30 words
The process of claim 1 wherein the concentration of said binder resin or polymer in said second solution is in the range of from about 0.1 to about 20 percent.
Claim 19
Dependent Claim
30 words
The process of claim 16 wherein the concentration of said binder resin or polymer in said second solution is in the range of from about 0.1 to about 10 percent.
Claim 20
Dependent Claim
30 words
The process of claim 18 wherein the concentration of said binder resin or polymer in said second solution is in the range of from about 1 to about 5 percent.
Claim 21
Dependent Claim
30 words
The process of claim 17 wherein the concentration of said precipitating agent in said first solution or dispersion is in the range of from about 2.5 to about 7.5 percent.
Claim 22
Dependent Claim
57 words
The process of claim 1 wherein said second solution is applied to said wetted web of step (1) in an amount such that the total weight of said binder resin or polymer added to said wetted web of step (1) is from about 1 to about 30 percent based on the dry weight of said hydrophobic web.
Claim 23
Dependent Claim
57 words
The process of claim 20 wherein said second solution is applied to said wetted web of step (1) in an amount such that the total weight of said binder resin or polymer added to said wetted web of step (1) is from about 5 to about 15 percent based on the dry weight of said hydrophobic web.
Claim 24
Dependent Claim
42 words
The process of claim 1 wherein the weight ratio of said binder resin or polymer to said precipitating agent in said wetted web of step (2) just prior to said working of said wetted web is from about 4:1 to about 1:1.
Claim 25
Dependent Claim
15 words
The process of claim 23 wherein said ratio is from about 2:1 to about 1:1.
Claim 26
Dependent Claim
14 words
The process of claim 1 wherein said precipitating agent comprises an anionic precipitating agent.
Claim 27
Dependent Claim
22 words
The process of claim 25 wherein said anionic precipitating agent contains anionic groups selected from the class consisting of carboxylate and sulfonate.
Claim 28
Dependent Claim
17 words
The process of claim 26 wherein said anionic precipitating agent is a water-soluble, self-catalyzed, thermosetting, acrylic resin.
Claim 29
Dependent Claim
24 words
The process of any one of claims 1 to 27 wherein said water-soluble, non-colloidal, cationic, thermosetting binder resin or polymer comprises an epoxy-functional polyamido/polyamino-epichlorohydrin.
Claim 30
Dependent Claim
28 words
The process of any one of claims 1 to 27 wherein said water-soluble, non-colloidal, cationic, thermosetting binder resin or polymer comprises an epoxy-functional polyamine-epichlorohydrin containing quaternary ammonium groups.
Claim 31
Dependent Claim
62 words
The process of any one of claims 1 to 27 wherein, prior to applying said first solution or dispersion to said web step (1), a mixture comprising water and a wetting agent is applied to said web to prewet said web followed by washing the prewetted web with water to remove said wetting agent while maintaining the web in a water-wetted form.
Claim 32
Dependent Claim
192 words
A process for converting a hydrophobic web comprised of polymeric microfibers to a hydrophilic, microfibrous, polymeric filter sheet exhibiting a positive zeta potential comprising: (1) applying a first solution of a water-soluble, non-colloidal, cationic, thermosetting binder resin or polymer to said web to at least partially wet said web within said first solution; (2) applying a second solution or dispersion of a precipitating agent to the wetted web of step (1) above to form a web wetted with a mixture of said first solution and said second solution or dispersion; (3) working the wetted web of step (2) above to mix said first solution and said second solution or dispersion thereby facilitating the precipitation of said binder resin or polymer and the distribution thereof as a coating on the surfaces of the microfibers of the worked web; and (4) drying the coated web of step (3) above and curing the precipitated binder resin or polymer to provide a hydrophilic, microfibrous, polymeric filter sheet with a positive zeta potential and which is further characterized by the surfaces of the microfibers therein being coated with a cured, precipitated, thermoset, cationic binder resin or polymer.
Claim 33
Dependent Claim
192 words
A process for converting a hydrophobic web comprised of polymeric microfibers to a hydrophilic, microfibrous, polymeric filter sheet exhibiting a positive zeta potential comprising: (1) applying a first solution of a water-soluble, non-colloidal, cationic, thermosetting binder resin or polymer to said web to at least partially wet said web within said first solution; (2) applying a second solution or dispersion of a precipitating agent to the wetted web of step (1) above to form a web wetted with a mixture of said first solution and said second solution or dispersion; (3) working the wetted web of step (2) above to mix said first solution and said second solution or dispersion thereby facilitating the precipitation of said binder resin or polymer and the distribution thereof as a coating on the surfaces of the microfibers of the worked web; and (4) drying the coated web of step (3) above and curing the precipitated binder resin or polymer to provide a hydrophilic, microfibrous, polymeric filter sheet with a positive zeta potential and which is further characterized by the surfaces of the microfibers therein being coated with a cured, precipitated, thermoset, cationic binder resin or polymer.
Claim 34
Dependent Claim
43 words
The process of claim 31 wherein said working of the wetted web of step (2) is carried out by contacting said wetted web with a roller rotating counter to the direction said wetted web is moving as the web moves past said roller.
Claim 35
Dependent Claim
18 words
The process of claim 32 wherein steps (1), (2) and (3) are carried out in a continuous manner.
Claim 36
Dependent Claim
45 words
The process of claim 33 wherein in step (1) said web is saturated with said first solution following which a portion of said first solution is removed from said wetted web of step (1) prior to applying said second solution or dispersion in step (2).
Claim 37
Dependent Claim
40 words
The process of claim 31 wherein said drying and said curing in step (4) are carried out at an elevated temperature of from about 50 to about 150 degrees Centigrade for a period of from several minutes to several days.
Claim 38
Dependent Claim
41 words
The process of claim 35 wherein said drying and said curing in step (4) are carried out at an elevated temperature of from about 75 to about 130 degrees Centigrade for a period of from about 5 to about 60 minutes.
Claim 39
Dependent Claim
41 words
The process of claim 31 wherein said polymeric microfibers of said hydrophobic web are comprised of a polyolefin and said hydrophobic web is prewet with a wetting solution comprising water and a wetting agent prior to step (1) of claim 31.
Claim 40
Dependent Claim
10 words
The process of claim 37 wherein said polyolefin is polypropylene.
Claim 41
Dependent Claim
18 words
The process of claim 31 wherein said polymeric microfibers of said hydrophobic web are comprised of a polyamide.
Claim 42
Dependent Claim
11 words
The process of claim 39 wherein said polyamide is nylon 66.
Claim 43
Dependent Claim
11 words
The process of claim 39 wherein said polyamide is nylon 11.
Claim 44
Dependent Claim
18 words
The process of claim 31 wherein said polymeric microfibers of said hydrophobic web are comprised of a polyester.
Claim 45
Dependent Claim
11 words
The process of claim 42 wherein said polyester is polyethylene terephthalate.
Claim 46
Dependent Claim
11 words
The process of claim 42 wherein said polyester is polybutylene terephthalate.
Claim 47
Dependent Claim
38 words
The process of claim 31 wherein said hydrophobic web is comprised of microfibers having diameters of from about 0.5 to about 20 micrometers and said hydrophobic web has pore sizes of from about 0.5 to about 80 micrometers.
Claim 48
Dependent Claim
35 words
The process of claim 45 wherein said microfibers have diameters of from about 1.0 to about 10 micrometers and said hydrophobic web has an absolute pore rating of from about 0.6 to about 10 micrometers.
Claim 49
Dependent Claim
30 words
The process of claim 31 wherein the concentration of said binder resin or polymer in said first solution is in the range of from about 0.1 to about 20 percent.
Claim 50
Dependent Claim
30 words
The process of claim 47 wherein the concentration of said binder resin or polymer in said first solution is in the range of from about 0.1 to about 10 percent.
Claim 51
Dependent Claim
30 words
The process of claim 48 wherein the concentration of said binder resin or polymer in said first solution is in the range of from about 1 to about 5 percent.
Claim 52
Dependent Claim
30 words
The process of claim 49 wherein the concentration of said precipitating agent in said second solution or dispersion is in the range of from about 2.5 to about 7.5 percent.
Claim 53
Dependent Claim
55 words
The process of claim 31 wherein said first solution is applied to said web in step (1) in an amount such that the total weight of said binder resin or polymer added to said web in step (1) is from about 1 to about 30 percent based on the dry weight of said hydrophobic web.
Claim 54
Dependent Claim
55 words
The process of claim 51 wherein said first solution is applied to said web in step (1) in an amount such that the total weight of said binder resin or polymer added to said web in step (1) is from about 5 to about 15 percent based on the dry weight of said hydrophobic web.
Claim 55
Dependent Claim
42 words
The process of claim 31 wherein the weight ratio of said binder resin or polymer to said precipitating agent in said wetted web of step (2) just prior to said working of said wetted web is from about 4:1 to about 1:1.
Claim 56
Dependent Claim
15 words
The process of claim 53 wherein said ratio is from about 2:1 to about 1:1.
Claim 57
Dependent Claim
14 words
The process of claim 31 wherein said precipitating agent comprises an anionic precipitating agent.
Claim 58
Dependent Claim
22 words
The process of claim 55 wherein said anionic precipitating agent contains anionic groups selected from the class consisting of carboxylate and sulfonate.
Claim 59
Dependent Claim
17 words
The process of claim 56 wherein said anionic precipitating agent is a water-soluble, self-catalyzed, thermosetting, acrylic resin.
Claim 60
Dependent Claim
24 words
The process of any one of claims 31 to 57 wherein said water-soluble, non-colloidal, cationic, thermosetting binder resin or polymer comprises an epoxy-functional polyamido/polyamino-epichlorohydrin.
Claim 61
Dependent Claim
28 words
The process of any one of claims 31 to 57 wherein said water-soluble, non-colloidal, cationic, thermosetting binder resin or polymer comprises an epoxy-functional polyamine-epichlorohydrin containing quaternary ammonium groups.
Claim 62
Dependent Claim
61 words
The process of any one of claims 31 to 57 wherein, prior to applying said first solution to said web in step (1), a mixture comprising water and a wetting agent is applied to said web to prewet said web followed by washing the prewetted web with water to remove said wetting agent while maintaining the web in a water-wetted form.
Claim 63
Dependent Claim
48 words
A microfibrous, polymeric filter sheet comprised of a normally hydrophobic, microfibrous, polymeric web wherein the surfaces of the polymeric microfibers of said web are coated with a cured, precipitated, cationic, thermoset binder resin or polymer, said filter sheet characterized by being hydrophilic and having a positive zeta potential.
Claim 64
Dependent Claim
48 words
A microfibrous, polymeric filter sheet comprised of a normally hydrophobic, microfibrous, polymeric web wherein the surfaces of the polymeric microfibers of said web are coated with a cured, precipitated, cationic, thermoset binder resin or polymer, said filter sheet characterized by being hydrophilic and having a positive zeta potential.
Claim 65
Dependent Claim
18 words
The filter sheet of claim 61 wherein said polymeric microfibers of said web are comprised of a polyolefin.
Claim 66
Dependent Claim
11 words
The filter sheet of claim 62 wherein said polyolefin is polypropylene.
Claim 67
Dependent Claim
11 words
The filter sheet of claim 62 wherein said polyolefin is polyethylene.
Claim 68
Dependent Claim
18 words
The filter sheet of claim 61 wherein said polymeric microfibers of said web are comprised of a polyamide.
Claim 69
Dependent Claim
12 words
The filter sheet of claim 65 wherein said polyamide is nylon 66.
Claim 70
Dependent Claim
12 words
The filter sheet of claim 65 wherein said polyamide is nylon 11.
Claim 71
Dependent Claim
18 words
The filter sheet of claim 61 wherein said polymeric microfibers of said web are comprised of a polyester.
Claim 72
Dependent Claim
12 words
The filter sheet of claim 68 wherein said polyester is polyethylene terephthalate.
Claim 73
Dependent Claim
12 words
The filter sheet of claim 61 wherein said polyester is polybutylene terephthalate.
Claim 74
Dependent Claim
26 words
The filter sheet of claim 61 wherein the microfibers of said normally hydrophobic, microfibrous, polymeric web have diameters of from about 0.5 to about 20 micrometers.
Claim 75
Dependent Claim
19 words
The filter sheet of claim 71 wherein said microfibers have diameters of from about 1.0 to about 10 micrometers.
Claim 76
Dependent Claim
26 words
The filter sheet of claim 61 wherein said filter sheet is further characterized by having absolute pore ratings of from about 0.5 to about 80 micrometers.
Claim 77
Dependent Claim
26 words
The filter sheet of claim 73 wherein said filter sheet is further characterized by having absolute pore ratings of from about 0.5 to about 10 micrometers.
Claim 78
Dependent Claim
41 words
The filter sheet of claim 61 wherein said, cured, precipitated, cationic, thermoset binder resin or polymer is present in an amount of from about 1 to about 30 percent based on the dry weight of said normally hydrophobic, microfibrous, polymeric web.
Claim 79
Dependent Claim
28 words
The filter sheet of claim 61 wherein said filter sheet is further characterized by a dry tensile strength of from about 2 to about 15 pounds per inch.
Claim 80
Dependent Claim
27 words
The filter sheet of claim 61 wherein said filter sheet has a positive zeta potential over the entire pH range of from about 3 to about 10.
Claim 81
Dependent Claim
30 words
The filter sheet of claim 61 wherein said filter sheet is further characterized by having a removal rating of negatively charged particles as low as about 0.1 micrometers or finer.
Claim 82
Dependent Claim
40 words
The filter sheet of claim 61 wherein said filter sheet is further characterized by the coating of said cured, precipitated, cationic, thermoset binder resin or polymer being of substantially uniform thickness on the surfaces of the microfibers of said web.
Claim 83
Dependent Claim
27 words
The filter sheet of claim 61 wherein said cured, precipitated, cationic, thermoset binder resin or polymer was precipitated with a precipitating agent comprising an anionic precipitating agent.
Claim 84
Dependent Claim
23 words
The filter sheet of claim 80 wherein said anionic precipitating agent contained anionic groups selected from the class consisting of carboxylate and sulfonate.
Claim 85
Dependent Claim
18 words
The filter sheet of claim 81 wherein said anionic precipitating agent was a water-soluble, self-catalyzed, thermosetting, acrylic resin.
Claim 86
Dependent Claim
25 words
The filter sheet of any one of claims 61 to 82 wherein said cured, precipitated, cationic, thermoset binder resin or polymer comprises an epoxy-functional polyamido/polyamino-epichlorohydrin.
Claim 87
Dependent Claim
29 words
The filter sheet of any one of claims 61 to 82 wherein said water-soluble, non-colloidal, cationic, thermosetting binder resin or polymer comprises an epoxy-functional polyamine-epichlorohydrin containing quaternary ammonium groups.
Claim 88
Dependent Claim
18 words
The filter sheet of claim 61 wherein said filter sheet is in the form of a filter element.
Claim 89
Dependent Claim
22 words
The filter sheet of claim 61 wherein said filter sheet has been formed into a pleated form and incorporated into a cartridge.
Claim 90
Independent Claim
30 words
A method for the filtration of particulates from a filter medium comprising passing said medium through the filter sheet of any one of claims 61 to 82, 85 or 86.
Claim 91
Dependent Claim
11 words
The method of claim 87 wherein said fluid medium is water.
Claim 92
Dependent Claim
24 words
A process for converting a hydrophobic web comprised of polymeric microfibers to a hydrophilic, microfibrous, polymeric filter sheet exhibiting a positive zeta potential comprising:
Claim 93
Dependent Claim
24 words
A process for converting a hydrophobic web comprised of polymeric microfibers to a hydrophilic, microfibrous, polymeric filter sheet exhibiting a positive zeta potential comprising:
Claim 94
Dependent Claim
50 words
(1) substantially simultaneously applying (a) a first solution or dispersion of a precipitating agent and (b) a second solution of a water-soluble, non-colloidal, cationic, thermosetting binder resin or polymer to said web to form a web wetted with a mixture of said first solution or dispersion and said second solution;
Claim 95
Dependent Claim
50 words
(1) substantially simultaneously applying (a) a first solution or dispersion of a precipitating agent and (b) a second solution of a water-soluble, non-colloidal, cationic, thermosetting binder resin or polymer to said web to form a web wetted with a mixture of said first solution or dispersion and said second solution;
Claim 96
Dependent Claim
48 words
(2) working the wetted web of step (1) above to mix said first solution or dispersion and said second solution, thereby facilitating the precipitation of said binder resin or polymer and the distribution thereof as a coating on the surfaces of the microfibers of the worked web; and
Claim 97
Dependent Claim
48 words
(2) working the wetted web of step (1) above to mix said first solution or dispersion and said second solution, thereby facilitating the precipitation of said binder resin or polymer and the distribution thereof as a coating on the surfaces of the microfibers of the worked web; and
Claim 98
Dependent Claim
54 words
(3) drying the coated web of step (2) above and curing the precipitated binder resin or polymer to provide a hydrophilic, microfibrous, polymeric filter sheet with a positive zeta potential and which is further characterized by the surfaces of the microfibers therein being coated with a cured, precipitated, thermoset, cationic binder resin or polymer.
Claim 99
Dependent Claim
54 words
(3) drying the coated web of step (2) above and curing the precipitated binder resin or polymer to provide a hydrophilic, microfibrous, polymeric filter sheet with a positive zeta potential and which is further characterized by the surfaces of the microfibers therein being coated with a cured, precipitated, thermoset, cationic binder resin or polymer.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1989-10-13 | 1990-04-14 | 1990-10-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-10-13 | 1994-04-14 | 1994-10-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-10-13 | 1998-04-14 | 1998-10-14 | $7700.00 | Window Closed / Lapsed |