US3773533A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for the manufacture of gypsum board
Assignee: Mitsui Toatsu Chemicals Inc
•
Filing: 1971-10-04
•
Granted: 1973-11-20
•
Expires: 1991-10-04
Abstract
Abstract A process for the manufacture of a gypsum board wherein Alpha type hemihydrate gypsum by-produced in the wet process of phosphoric acid manufacturing is ground and mixed with water and a metal ion of iron or aluminum to form an aqueous slurry containing said gypsum and said slurry is enclosed between two sheets of board paper while maintaining the pH value of said slurry at 4 to 7, thereby said slurry sets to form said gypsum board.
Inventors
- 👤 T Omoto
- 👤 T Inoue
- 👤 H Aizawa
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 06:26
CPC Classifications
C; C04; C04B; C04B28/00; C04B28/14; C04B28/145; C04B28/146
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
59 words
A process as claimed in claim 1 wherein a water-soluble salt of a metal selected from the group consisting of aluminum and iron is added as said metal ion to said hemihydrate gypsum in an amount of 0.3 to 3.0 parts by weight as hydrate of said salt per 100 parts by weight of said Alpha -type hemihydrate gypsum.
Claim 2
Dependent Claim
58 words
A process as claimed in claim 1 wherein a water-soluble salt of a metal selected from the group consisting of aluminum and iron is added as said metal ion to said slurry in an amount of 0.3 to 3.0 parts by weight as hydrate of said salt per 100 parts by weight of said Alpha -type hemihydrate gypsum.
Claim 3
Dependent Claim
35 words
A process as claimed in claim 1 wherein said pH value is maintained by adding a member selected from thE group consisting of basic compounds of alkali metals and alkaline earth metals to said slurry.
Claim 4
Dependent Claim
25 words
A process as claimed in claim 1 wherein said Alpha -type hemihydrate gypsum is ground to a specific surface area between 2,500 and 5,000 cm2/g.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-11-19 | 1977-05-21 | 1977-11-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-11-19 | 1981-05-21 | 1981-11-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-11-19 | 1985-05-21 | 1985-11-20 | $7700.00 | Window Closed / Lapsed |