Patent US4390574A successfully refreshed from Google Patents.
US4390574A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Felt material of layer of fine denier felt and layer of coarse denier felt
Assignee: Insituform Netherlands BV
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Filing: 1981-07-31
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Granted: 1983-06-28
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Expires: 2001-07-31
Abstract
Abstract The present invention relates to the provision of a filling material such as an inorganic filler in the felt, especially a needled felt. The resulting felt material is formed into a tube for use in a passageway lining process in which the felt material is soaked in a curable resin. The purpose of the filling material is to reduce the quantity of resin required to impregnate the felt, thereby to reduce the cost of the process.
Inventors
- 👤 Eric Wood
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 18:43
CPC Classifications
D; D04; D04H; D04H1/00; D04H1/40; D04H1/42; D04H1/4209; D04H1/4218; D04H1/44; D04H1/46; D04H1/48; D04H1/488; D04H1/498; Y; Y10; Y10T; Y10T428/00; Y10T428/13; Y10T428/131; Y10T428/1314; Y10T428/1352; Y10T428/1362; Y10T428/24; Y10T428/24942; Y10T442/00; Y10T442/50; Y10T442/57
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
41 words
A felt material comprising (a) at least one layer of felt of fine denier, (b) at least one layer of felt of coarse denier, and (c) a filling material having a specific gravity substantially the same as that of said felt.
Claim 2
Dependent Claim
41 words
A felt material comprising (a) at least one layer of felt of fine denier, (b) at least one layer of felt of coarse denier, and (c) a filling material having a specific gravity substantially the same as that of said felt.
Claim 3
Dependent Claim
53 words
A felt material according to claim 1, wherein said felt material is formed into a tube, said at least one layer of felt of fine denier being adjacent the outer surface of said tube, and said at least one layer of felt of coarse denier being adjacent the inner surface of said tube.
Claim 4
Dependent Claim
22 words
A felt material according to claim 2, wherein the outer surface of said felt tube is coated with a liquid impermeable membrane.
References Cited (Backward Citations)
GB1449455A
Cited
US4250172A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-06-27 | 1986-12-27 | 1987-06-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-06-27 | 1990-12-27 | 1991-06-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-06-27 | 1994-12-27 | 1995-06-28 | $7700.00 | Window Closed / Lapsed |