Patent US4961891A successfully refreshed from Google Patents.
US4961891A
Expired / Lapsed
US
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Method of making high compressibility gasket material
Assignee: Garlock Sealing Technologies LLC
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Filing: 1989-11-15
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Granted: 1990-10-09
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Expires: 2009-11-15
Abstract
Abstract A highly compressible gasket material is formed by fusing two filled sheets of PTFE containing dispersed microballoons to a central unfilled sheet of PTFE which provides tensile strength to the material. The two unfilled sheets each constitute from 20% to 25% of the overall thickness of the gasket material. This method provides a unitary gasket assembly having an overall compressibility of 45% or more, but the thicker unfilled PTFE central area of the assembly provides excellent recovery characteristics and resistance to creep relaxation.
Inventors
- 👤 Stefan Pitolaj
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 19:23
CPC Classifications
B; B29; B29C; B29C67/00; B29C67/02; B29C67/04; F; F16; F16J; F16J15/00; F16J15/02; F16J15/06; F16J15/10; F16J15/104; F16L; F16L23/00; F16L23/16; F16L23/18; F16L49/00; F16L49/04
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
75 words
A method for forming a gasket material which includes: forming first and second sheets of unsintered polytetrafluoroethylene having fully embedded, hollow, rigid collapsible particles dispersed therein and bonded thereto, forming a third sheet of unsintered polytetrafluoroethylene, positioning said third sheet between said first and second sheets to form a three layered structure, sintering said three layered structure at temperatures above the gel point of polytetrafluoroethylene to fuse the three layers into a unitary gasket structure.
Claim 2
Independent Claim
75 words
A method for forming a gasket material which includes: forming first and second sheets of unsintered polytetrafluoroethylene having fully embedded, hollow, rigid collapsible particles dispersed therein and bonded thereto, forming a third sheet of unsintered polytetrafluoroethylene, positioning said third sheet between said first and second sheets to form a three layered structure, sintering said three layered structure at temperatures above the gel point of polytetrafluoroethylene to fuse the three layers into a unitary gasket structure.
Claim 3
Dependent Claim
26 words
The method of claim 1 which includes forming said third sheet to have at least twice the thickness of each of said first and second sheets.
Claim 4
Dependent Claim
37 words
The method of claim 1 which includes forming each of said first and second sheets to a thickness which is within the range of from 20% to 25% of the total thickness of said three layered structure.
Claim 5
Dependent Claim
28 words
The method of claim 1 which includes forming each of said first and second sheets so that said hollow particles constitute from 15% to 25% by weight thereof.
Claim 6
Dependent Claim
28 words
The method of claim 4 which includes forming each of said first and second sheets so that said hollow particles constitute between 18% and 21% by weight thereof.
Claim 7
Dependent Claim
37 words
The method of claim 5 which includes forming each of said first and second sheets to a thickness which is within the range of from 20% to 25% of the total thickness of said three layered structure.
Claim 8
Dependent Claim
55 words
The method of claim 1 which includes forming each of said first and second sheets by mixing polytetrafluoroethylene in powdered form with a liquid and glass microballoons and mixing the resultant composite to disperse the glass microballoons, filtering the composite to remove excess liquid therefrom and calendering the composite to form a particle containing sheet.
Claim 9
Dependent Claim
25 words
The method of claim 7 which includes adding said microballoons in sufficient quantity to form 15% to 25% by weight of said particle containing sheet.
Claim 10
Dependent Claim
37 words
The method of claim 8 which includes forming each of said first and second sheets to a thickness which is within the range of from 20% to 25% of the total thickness of said three layered structure.
References Cited (Backward Citations)
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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) | 1993-10-08 | 1994-04-09 | 1994-10-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-10-08 | 1998-04-09 | 1998-10-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-10-08 | 2002-04-09 | 2002-10-09 | $7700.00 | Window Closed / Lapsed |