US4210697A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for preparing hydrophobic porous fibrous sheet material of high strength and porosity and product
Assignee: Pall Corp
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Filing: 1978-09-15
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Granted: 1980-07-01
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Expires: 1998-09-15
Abstract
Abstract A process is provided for preparing hydrophobic porous fibrous sheet material suitable for use as a filter due to its inertness, strength, resistance to deterioration at elevated temperatures, and porosity, comprising impregnating a porous fibrous substrate with an aqueous dispersion consisting essentially of polytetrafluoroethylene or polytrifluorochloroethylene in an amount within the range from about 2 to about 40% by weight of the emulsion, and a silicone resin prepolymer such as a reactive polydimethylsiloxane in an amount within the range from about 0.1 to about 8% by weight of the emulsion; and drying the substrate at a temperature above about 525° F. to cure the silicone resin prepolymer, forming a hydrophobic polymer, and sinter-bond the polytetrafluoroethylene or polytrifluorochloroethylene thereto and to the substrate, thereby forming a hydrophobic porous fibrous sheet material that is inert, has a high strength, and a high resistance to deterioration at elevated temperature; each of the silcone polymer and polytetrafluoroethylene or polytrifluorochloroethylene unexpectedly synergizing the hydrophobicity and strength imparted to the substrate by the other. A hydrophobic porous fibrous sheet material also is provided, comprising a substrate of porous fibrous sheet material impregnated with a composition consisting essentially of polytetrafluoroethylene or polytrifluorochloroethylene and a silicone resin, said polytetrafluoroethylene or polytrifluorochloroethylene being sinter-bonded to the silicone resin and to the substrate, each of the silicone polymer and polytetrafluoroethylene or polytrifluorochloroethylene synergizing the hydrophobicity and strength imparted to the substrate by the other.
Inventors
- 👤 Joseph G. Adiletta
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 19:19
CPC Classifications
D; D06; D06M; D06M15/00; D06M15/19; D06M15/21; D06M15/244; D06M15/256; D06M15/37; D06M15/643; Y; Y10; Y10T; Y10T442/00; Y10T442/20; Y10T442/2221; Y10T442/223
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
156 words
A process for preparing a hydrophobic porous fibrous sheet material which comprises impregnating a substrate of porous fibrous sheet material with an aqueous dispersion consisting essentially of at least one polymer selected from the group consisting of polytetrafluoroethylene and polytrifluorochloroethylene in an amount within the range from about 2 to about 40% by weight of the emulsion, and a silicone resin prepolymer in an amount within the range from about 0.1 to about 8% by weight of the emulsion; and drying the substrate at a temperature above about 525° F. to cure the silicone resin prepolymer, formingg a hydrophobic polymer, and sinter-bond the polytetrafluoroethylene or polytrifluorochloroethylene thereto and to the substrate, thereby forming a hydrophobic porous fibrous sheet material that is inert, has a high strength and a high resistance to deterioration at elevated temperature; each of the silicone polymer and polytetrafluoroethylene or polytrifluorochloroethylene synergizing the hydrophobicity and strength imparted to the substrate by the other.
Claim 2
Dependent Claim
156 words
A process for preparing a hydrophobic porous fibrous sheet material which comprises impregnating a substrate of porous fibrous sheet material with an aqueous dispersion consisting essentially of at least one polymer selected from the group consisting of polytetrafluoroethylene and polytrifluorochloroethylene in an amount within the range from about 2 to about 40% by weight of the emulsion, and a silicone resin prepolymer in an amount within the range from about 0.1 to about 8% by weight of the emulsion; and drying the substrate at a temperature above about 525° F. to cure the silicone resin prepolymer, formingg a hydrophobic polymer, and sinter-bond the polytetrafluoroethylene or polytrifluorochloroethylene thereto and to the substrate, thereby forming a hydrophobic porous fibrous sheet material that is inert, has a high strength and a high resistance to deterioration at elevated temperature; each of the silicone polymer and polytetrafluoroethylene or polytrifluorochloroethylene synergizing the hydrophobicity and strength imparted to the substrate by the other.
Claim 3
Dependent Claim
34 words
A process in accordance with claim 1, in which the substrate is a preformed fibrous substrate selected from the group consisting of woven and nonwoven sheet material, cloth and fabric, mats, webs and batts.
Claim 4
Dependent Claim
42 words
A process in accordance with claim 1, in which said substrate is impregnated by mixing the polymer and prepolymer with the fibrous material of which the substrate is to be formed and then forming the substrate of impregnated porous fibrous sheet material.
Claim 5
Dependent Claim
45 words
A process in accordance with claim 3, in which said mixing is carried out by blending an aqueous dispersion of said polymer and prepolymer with a slurry of the fibrous material of which the substrate is to be formed and then forming said sheet material.
Claim 6
Dependent Claim
14 words
A process in accordance with claim 1, in which the fibrous material is hydrophilic.
Claim 7
Dependent Claim
16 words
A process in accordance with claim 5, in which the hydrophilic fibrous material comprises synthetic fibers.
Claim 8
Dependent Claim
14 words
A process in accordance with claim 1, in which the fibrous material is hydrophobic.
Claim 9
Dependent Claim
16 words
A process in accordance with claim 7, in which the hydrophobic fibrous material comprises inorganic fibers.
Claim 10
Dependent Claim
17 words
A process in accordance with claim 8, in which the inorganic fibers are glass or mineral wool.
Claim 11
Dependent Claim
13 words
A process in accordance with claim 1, in which the polymer is polytetrafluoroethylene.
Claim 12
Dependent Claim
13 words
A process in accordance with claim 1, in which the polymer is polytrifluorochloroethylene.
Claim 13
Dependent Claim
16 words
A process in accordance with claim 1, in which the silicone resin prepolymer is a polysiloxane.
Claim 14
Dependent Claim
14 words
A process in accordance with claim 12, in which the polysiloxane is polydimethyl siloxane.
Claim 15
Dependent Claim
26 words
A process in accordance with claim 1, in which the dispersion is applied to the substrate by dipping the substrate in a body of aqueous dispersion.
Claim 16
Dependent Claim
24 words
A process in accordance with claim 1, in which the dispersion is applied to the substrate by spraying the aqueous dispersion on the substrate.
Claim 17
Dependent Claim
19 words
A process in accordance with claim 1, in which the dispersion is applied to the substrate by kissing rolls.
Claim 18
Dependent Claim
25 words
A process in accordance with claim 1, in which the dispersion is applied to the substrate by spreading or coating the dispersion on the substrate.
Claim 19
Dependent Claim
44 words
A process in accordance with claim 1, in which the curing of the silicone polymer is effected by heating the impregnated material at a temperature in excess of about 250° F., and then the polymer is sinter-bonded at a temperature above about 620° F.
Claim 20
Dependent Claim
95 words
A hydrophobic porous fibrous sheet material comprising a composition consisting essentially of a substrate of porous fibrous sheet material impregnated with a polymer selected from the group consisting of polytetrafluoroethylene and polytrifluorochloroethylene in an amount within the range from about 3% to about 15%, and a silicone resin in an amount within the range from about 0.1% to about 8%, said polytetrafluoroethylene or polytrifluorochloroethylene being sinter-bonded to the silicone resin and to the substrate, each of the silicone polymer and polytetrafluoroethylene or polytrifluorochloroethylene synergizing the hydrophobicity and strength imparted to the substrate by the other.
Claim 21
Dependent Claim
95 words
A hydrophobic porous fibrous sheet material comprising a composition consisting essentially of a substrate of porous fibrous sheet material impregnated with a polymer selected from the group consisting of polytetrafluoroethylene and polytrifluorochloroethylene in an amount within the range from about 3% to about 15%, and a silicone resin in an amount within the range from about 0.1% to about 8%, said polytetrafluoroethylene or polytrifluorochloroethylene being sinter-bonded to the silicone resin and to the substrate, each of the silicone polymer and polytetrafluoroethylene or polytrifluorochloroethylene synergizing the hydrophobicity and strength imparted to the substrate by the other.
Claim 22
Dependent Claim
17 words
A hydrophobic porous fibrous sheet material in accordance with claim 19 in which the polymer is polytetrafluoroethylene.
Claim 23
Dependent Claim
17 words
A hydrophobic porous fibrous sheet material in accordance with claim 19 in which the polymer is polytrifluorochloroethylene.
Claim 24
Dependent Claim
19 words
A hydrophobic porous fibrous sheet material in accordance with claim 19 in which the silicone polymer is a polysiloxane.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1983-07-01 | 1983-12-31 | 1984-07-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-07-01 | 1987-12-31 | 1988-07-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-07-01 | 1991-12-31 | 1992-07-01 | $7700.00 | Window Closed / Lapsed |