Patent US3870538A successfully refreshed from Google Patents.
US3870538A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Gypsum set accelerator
Assignee: National Gypsum Co
•
Filing: 1973-05-07
•
Granted: 1975-03-11
•
Expires: 1993-05-07
Abstract
Abstract A gypsum set accelerator, produced by compression milling a mixture of ground gypsum rock and starch, and the addition thereof to an aqueous slurry of settable calcined gypsum such as in the forming of paper-covered gypsum wallboard.
Inventors
- 👤 Edward A Burkard
- 👤 Donald A Kossuth
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 15:20
CPC Classifications
C; C04; C04B; C04B28/00; C04B28/14; C04B2103/00; C04B2103/10; C04B2103/12; C04B2111/00; C04B2111/00474; C04B2111/00612; C04B2111/0062
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
43 words
AN ACCELERATOR FOR ACCELERATING THE SETTING REACTION OF CALCIUM SULFATE HEMI-HYDRATE AND WATER CONSISTING ESSENTIALLY OF THE FINELY GROUND PRODUCT OF A COMPRESION MILLING OF A MIXTURE OF ABOUT 1 TO 99 PERCENT ALCIUM SULFATE DIHYDRATE AND ABOUT 1 TO 99 PERCENT STARCH.
Claim 2
Dependent Claim
43 words
AN ACCELERATOR FOR ACCELERATING THE SETTING REACTION OF CALCIUM SULFATE HEMI-HYDRATE AND WATER CONSISTING ESSENTIALLY OF THE FINELY GROUND PRODUCT OF A COMPRESION MILLING OF A MIXTURE OF ABOUT 1 TO 99 PERCENT ALCIUM SULFATE DIHYDRATE AND ABOUT 1 TO 99 PERCENT STARCH.
Claim 3
Dependent Claim
43 words
An accelerator for accelerating the setting reaction of calcium sulfate hemi-hydrate and water consisting essentially of the finely ground product of a compression milling of a mixture of about 1 to 99 percent calcium sulfate dihydrate and about 1 to 99 percent starch.
Claim 4
Dependent Claim
43 words
An accelerator for accelerating the setting reaction of calcium sulfate hemi-hydrate and water consisting essentially of the finely ground product of a compression milling of a mixture of about 1 to 99 percent calcium sulfate dihydrate and about 1 to 99 percent starch.
Claim 5
Dependent Claim
28 words
An accelerator as defined in claim 1 wherein said accelerator has a surface area as determined by a Fisher Sub-Sieve Sizer of from about 10,000 to 20,000 cm2/gm.
Claim 6
Dependent Claim
17 words
An accelerator as defined in claim 1 wherein said mixture ratio is from about 1:3 to 3:1.
References Cited (Backward Citations)
US2078199A
Cited
US3573947A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-03-10 | 1978-09-09 | 1979-03-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-03-10 | 1982-09-09 | 1983-03-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-03-10 | 1986-09-09 | 1987-03-11 | $7700.00 | Window Closed / Lapsed |