US3821074A
Expired / Lapsed
US
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Paper from pitch based organic fibers
Assignee: Unifrax I LLC
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Filing: 1972-12-07
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Granted: 1974-06-28
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Expires: 1992-12-07
Abstract
Abstract Bonded fibrous articles are made from mixtures of fusible and infusible pitch-novolac fibers, as well as similar mixtures of fusible and infusible novolac fibers. The fibrous mixtures are formed into the desired shapes and the fusible fibers are cured, forming firm bonds with the infusible fibers during the curing step. The resulting fibrous articles show excellent dimensional stability as well as chemical and thermal resistance. The fibers may be formed into flat sheet-like products which are suitable as thermal and electrical insulators and show good resistance against chemical attack.
Inventors
- 👤 R Lin
- 👤 H Murty
- 👤 A Pietrantuone
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 20:51
CPC Classifications
H; H01; H01B; H01B3/00; H01B3/18; H01B3/48; H01B3/485; D; D04; D04H; D04H1/00; D04H1/40; D04H1/58; D04H1/64; D21; D21H; D21H13/00; D21H13/10; D21H13/20; D21H13/22
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
13 words
A process according to claim 1 wherein said fusible fiber comprises a novolac.
Claim 2
Dependent Claim
18 words
A process according to claim 1 wherein said fusible fiber comprises said mixture of pyrogenous residue and novolac.
Claim 3
Dependent Claim
30 words
A process according to claim 1 wherein said mixture comprises about 20 percent fusible novolac fibers and about 80 percent infusible fibers of said mixture of pyrogenous residue and novolac.
Claim 4
Dependent Claim
17 words
A process according to claim 1 wherein the curing agent is an aldehyde combined with a catalyst.
Claim 5
Dependent Claim
17 words
A process according to claim 1 wherein the curing agent is an amine combined with a catalyst.
Claim 6
Dependent Claim
33 words
A process according to claim 1 wherein the fibers are compressed at a pressure less than 5 psi and heated to a temperature in the range of from about 90* to 200* C.
Claim 7
Dependent Claim
27 words
A process according to claim 7 wherein the heating step is followed by a second heating to a temperature range of from about 200* to 400* C.
Claim 8
Dependent Claim
92 words
A process according to claim 1 wherein the fiber mixture comprises about 20 percent fusible fibers and 80 percent infusible fibers, the mixture is suspended in water and deposited in a flat sheet upon a screen with the removal of water, followed by the addition of hexamethylenetetramine as a curing agent, the fibers being simultaneously compressed and heated at a temperature of from about 150* to 180* C, the pressure released and a second heating period continued at a temperature of from 200* to 370* C to form a bonded fibrous sheet.
Claim 9
Dependent Claim
169 words
A process for making an infusible fibrous sheet, comprising the steps of: a. Preparing a mixture of from 10 to 40 percent of fusible fibers and from 60 to 90 percent of infusible fibers, said fusible and infusible fibers selected from novolacs and pyrogenous residues combined with from 5 to 40 wt percent of a novolac, said novolac in each instance having two or more available sites for polymerization, said fibers being from about 0.1 micron to about 300 microns in diameter; b. Suspending said mixture in a fluid; c. Depositing said mixture of fibers upon a permeable support; d. Removing the fluid suspending agent from said fibers; e. Contacting the fibers with a curing agent selected from the group consisting of aldehydes and amines, in the presence of a catalyst; and, f. Compressing the fibers at a pressure less than 5 psi and simultaneously heating said fibers to a temperature of from about 90* to about 200* C for sufficient time to effect curing of the fusible fibers.
Claim 10
Dependent Claim
13 words
A process according to claim 10 wherein said fusible fibers comprise a novolac.
Claim 11
Dependent Claim
18 words
A process according to claim 10 wherein said fusible fibers comprise said mixture of pyrogenous residue and novolac.
Claim 12
Dependent Claim
30 words
A process according to claim 10 wherein said mixture comprises about 20 percent fusible novolac fibers and about 80 percent infusible fibers of said mixture of pyrogenous residue and novolac.
Claim 13
Dependent Claim
147 words
A bonded fibrous article comprising infusible fibers selected from the group consisting of novolac fibers, fibers of a pyrogenous residue combined from 5-40 wt percent of a novolac, and mixtures thereof, said article prepared by suspending, in a fluid a mixture comprising from 10 to 40 percent fusible fibers and from 60 to 90 percent infusible fibers, said fusible and infusible fibers each selected from the group consisting of novolac fibers and fibers of a pyrogenous residue combined with a novolac; depositing said mixture upon a substrate and removing said fluid; contacting said fibers with a catalyst and a curing agent selected from the group consisting of aldehydes and amines; and heating said fibers to a temperature of from 90* to 200* C under a pressure of less than 5 psi to cure said fusible fibers to an infusible state and to thereby bind said infusible fibers.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-06-27 | 1977-12-27 | 1978-06-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-06-27 | 1981-12-27 | 1982-06-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-06-27 | 1985-12-27 | 1986-06-28 | $7700.00 | Window Closed / Lapsed |