US4361619A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Filter of poly(tetrafluoroethylene) and glass fibers
Assignee: EIDP Inc
•
Filing: 1981-05-20
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Granted: 1982-11-30
•
Expires: 2001-05-20
Abstract
Abstract 65-99 percent by weight poly(tetrafluoroethylene) fibers and 1-35 percent by weight glass fibers are combined in an intimate blend suitable for the preparation of filter felts having reduced leakage while maintaining high permeability to gas flow.
Inventors
- 👤 Herman H. Forsten
- 👤 Peter E. Frankenburg
- 👤 Jagdish N. Shah
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 02:34
CPC Classifications
D; D04; D04H; D04H5/00; D04H5/02; D04H1/00; D04H1/40; D04H1/44; D04H1/46; B; B01; B01D; B01D39/00; B01D39/14; B01D39/16; B01D39/1607; B01D39/1623; B01D39/20; B01D39/2003; B01D39/2017; D04H1/42; D04H1/4209; D04H1/4218; D04H1/4282; D04H1/4318; D04H1/4374; D04H1/4382; D04H1/43835; D04H1/43838; Y; Y10; Y10S; Y10S55/00; Y10S55/05; Y10T; Y10T428/00; Y10T428/29; Y10T428/2904; Y10T442/00; Y10T442/10; Y10T442/102; Y10T442/159; Y10T442/16; Y10T442/60; Y10T442/682; Y10T442/684
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
37 words
An intimate blend of poly(tetrafluoroethylene) and glass staple fibers containing 65-99 percent by weight poly(tetrafluoroethylene) fibers having a denier per filament of 2-25 and 1-35 percent by weight glass fibers having a denier per filament of 0.1-1.
Claim 2
Dependent Claim
37 words
An intimate blend of poly(tetrafluoroethylene) and glass staple fibers containing 65-99 percent by weight poly(tetrafluoroethylene) fibers having a denier per filament of 2-25 and 1-35 percent by weight glass fibers having a denier per filament of 0.1-1.
Claim 3
Dependent Claim
16 words
An improved filter felt comprising a needled batt of the intimate fiber blend of claim 1.
Claim 4
Dependent Claim
15 words
The filter felt of claim 2 wherein 1-25 percent by weight glass fibers are used.
Claim 5
Dependent Claim
15 words
The filter felt of claim 2 wherein 1-10 percent by weight glass fibers are used.
Claim 6
Dependent Claim
20 words
The filter felt of claim 2 wherein one or more batts is needled into a supporting scrim of woven fibers.
Claim 7
Dependent Claim
15 words
The filter felt of claim 5 wherein the supporting scrim is made of poly(tetrafluoroethylene) fibers.
Claim 8
Dependent Claim
16 words
The filter felt of claim 2 wherein the poly(tetrafluoroethylene) fibers have a denier per filament 5-10.
Claim 9
Dependent Claim
17 words
The filter felt of claim 7 wherein the glass fibers have a denier per filament of 0.2-0.4.
Claim 10
Dependent Claim
88 words
Process for preparing the filter felt of claim 2 by blending 65-99 percent by weight poly(tetrafluoroethylene) fibers with 1-35 percent by weight glass fibers in a picker, further blending of the fibers in a carding machine, forming a nonwoven batt by crosslapping, combining layers of the batt if necessary to form a layered batt of the desired thickness, needling the batt with a needle loom to provide a felt and heat setting the felt by heating on a tenter frame for at least two minutes at 230°-325° C.
Claim 11
Dependent Claim
23 words
The process of claim 9 wherein the layered batt is needled into one or both sides of a woven scrim of poly(tetrafluoroethylene) fibers.
Claim 12
Dependent Claim
18 words
The process of claim 10 wherein the needle density is 200 to 400 needle penetrations per square centimeter.
References Cited (Backward Citations)
US2893105A
Cited
US2933154A
Cited
US3018845A
Cited
US3197946A
Cited
US3506133A
Cited
US3796659A
Cited
US3986851A
Cited
US4093437A
Cited
US4210540A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1985-11-29 | 1986-05-31 | 1986-11-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-11-29 | 1990-05-31 | 1990-11-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-11-29 | 1994-05-31 | 1994-11-30 | $7700.00 | Window Closed / Lapsed |