US4192707A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Heat treatment of chrysotile asbestos fibres
Assignee: Ortech Corp
•
Filing: 1977-12-29
•
Granted: 1980-03-11
•
Expires: 1997-12-29
Abstract
Abstract Asbestos fibres having excellent properties in resin reinforcement are produced by controlled heat treatment of a coarse fraction of chrysotile asbestos fibres.
Inventors
- 👤 Roger W. Glass
- 👤 Richard A. Kuntze
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 11:31
CPC Classifications
C; C08; C08K; C08K9/00; C01; C01B; C01B33/00; C01B33/20; C01B33/22; C04; C04B; C04B14/00; C04B14/38; C04B14/40
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
130 words
A method for the formation from Group 4 or Group 5 chrysotile asbestos fibres of long, very straight, smooth-surfaced, hard asbestos fibres having enhanced impact strength in resin reinforcement, which comprises: initially separating a coarse fraction from said chrysotile asbestos fibres and heat treating said coarse fraction to form said hard asbestos fibres; said heat treatment being effected by heating in an ambient atmosphere having a substantially uniform temperature of about 400° to about 600° C. for a time from about 1 to about 5 hours sufficient to increase the impact strength of the coarse fraction of fibres in resin reinforcement and insufficient to result in a loss of water of crystallization of the fibres of greater than about 2% by weight of the total weight of water of crystallization.
Claim 2
Independent Claim
130 words
A method for the formation from Group 4 or Group 5 chrysotile asbestos fibres of long, very straight, smooth-surfaced, hard asbestos fibres having enhanced impact strength in resin reinforcement, which comprises: initially separating a coarse fraction from said chrysotile asbestos fibres and heat treating said coarse fraction to form said hard asbestos fibres; said heat treatment being effected by heating in an ambient atmosphere having a substantially uniform temperature of about 400° to about 600° C. for a time from about 1 to about 5 hours sufficient to increase the impact strength of the coarse fraction of fibres in resin reinforcement and insufficient to result in a loss of water of crystallization of the fibres of greater than about 2% by weight of the total weight of water of crystallization.
Claim 3
Dependent Claim
31 words
The method of claim 1 wherein said heat treatment is effected to achieve a maximum increase in said impact strength properties without any loss of water of crystallization from the fibres.
Claim 4
Dependent Claim
31 words
The method of claim 1 wherein said heat treatment is effected in an ambient atmosphere at a temperature of about 500° to about 550° C. for about 2 to 3 hours.
Claim 5
Dependent Claim
18 words
The method of claim 1 wherein said fibres are in a pressure packed form during said heating step.
Claim 6
Dependent Claim
22 words
The method of claim 4 wherein said fibres are pressure packed to a density of about 25 to about 50 lb./cu. ft.
Claim 7
Dependent Claim
21 words
The method of claim 1 including opening said coarse fraction to an average surface area of about 3000 cm 2 /g.
References Cited (Backward Citations)
US2616801A
Cited
US3215494A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1983-03-11 | 1983-09-10 | 1984-03-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-03-11 | 1987-09-10 | 1988-03-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-03-11 | 1991-09-10 | 1992-03-11 | $7700.00 | Window Closed / Lapsed |