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Patent US4518652A successfully refreshed from Google Patents.
US4518652A
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Method for forming a lightweight cementitious structural product and product formed thereby
Assignee: United States Gypsum Co
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Filing: 1983-07-15
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Granted: 1985-05-21
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Expires: 2003-07-15
Abstract
Abstract A method for producing a lightweight set cementitious product, and more specifically, gypsum wallboard, having excellent strength and paper-to-core bond, which method comprises producing a foam comprising polyvinyl alcohol and water, introducing the foam thus formed into an aqueous cementitious slurry, depositing the slurry between paper cover sheets, and permitting the cementitious slurry to set. In a further embodiment an emulsion formed of asphalt and wax is added to the cementitious slurry to impart water resistance, the polyvinyl alcohol of the foaming agent cooperating with the asphalt and wax emulsion to improve the water resistant properties of the set gypsum wallboard.
Inventors
- 👤 Michael D. Willoughby
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 12:03
CPC Classifications
C; C04; C04B; C04B28/00; C04B28/14; C04B24/00; C04B24/24; C04B24/26; C04B24/2623; C04B2111/00; C04B2111/00474; C04B2111/00612; C04B2111/0062; Y; Y10; Y10T; Y10T428/00; Y10T428/249921; Y10T428/249953; Y10T428/249967; Y10T428/249968
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
66 words
A method for the production of a lightweight structural member, which comprises preparing a settable aqueous slurry of a cementitious material, mixing an aqueous foam into said slurry, forming said slurry into the proper shape for said structural member, and setting and drying said cementitious material, said foam being prepared by passing water and a foaming agent consisting essentially of polyvinyl alcohol through a foaming apparatus.
Claim 2
Independent Claim
66 words
A method for the production of a lightweight structural member, which comprises preparing a settable aqueous slurry of a cementitious material, mixing an aqueous foam into said slurry, forming said slurry into the proper shape for said structural member, and setting and drying said cementitious material, said foam being prepared by passing water and a foaming agent consisting essentially of polyvinyl alcohol through a foaming apparatus.
Claim 3
Dependent Claim
21 words
A method according to claim 1, wherein said cementitious material is calcium sulfate hemihydrate and said structural member is gypsum wallboard.
Claim 4
Dependent Claim
17 words
A method according to claim 2, wherein said polyvinyl alcohol is dissolved in said aqueous foaming agent.
Claim 5
Dependent Claim
18 words
A method according to claim 2, wherein said polyvinyl alcohol has a degree of hydrolysis of from 75%-95%.
Claim 6
Dependent Claim
17 words
A method according to claim 2, wherein said polyvinyl alcohol has a degree of hydrolysis of 87%-91%.
Claim 7
Dependent Claim
24 words
A method according to claim 2, wherein said foam has a density of from about 2 lbs to about 20 lbs per cubic foot.
Claim 8
Dependent Claim
22 words
A method according to claim 2, wherein an asphalt-wax emulsion is added to said aqueous slurry to render said gypsum board water-resistant.
Claim 9
Dependent Claim
45 words
A method according to claim 2, wherein said foam is formed by adding dry powdered polyvinyl alcohol to said water at ambient temperature, and passing the mixture through a foaming apparatus, whereby said polyvinyl alcohol becomes dissolved in said water and a foam is formed.
Claim 10
Dependent Claim
55 words
A lightweight structural member produced by preparing a settable aqueous slurry of a cementitious material, mixing an aqueous foam into said slurry, forming said slurry into the proper shape for said structural member, and setting and drying said cementitious material, said foam being prepared from water and a foaming agent consisting essentially of polyvinyl alcohol.
Claim 11
Dependent Claim
55 words
A lightweight structural member produced by preparing a settable aqueous slurry of a cementitious material, mixing an aqueous foam into said slurry, forming said slurry into the proper shape for said structural member, and setting and drying said cementitious material, said foam being prepared from water and a foaming agent consisting essentially of polyvinyl alcohol.
Claim 12
Dependent Claim
22 words
A structural member according to claim 9, wherein said cementitious material is calcium sulfate hemihydrate and said structural member is gypsum wallboard.
Claim 13
Dependent Claim
18 words
A structural member according to claim 10, wherein said polyvinyl alcohol is dissolved in said aqueous foaming agent.
Claim 14
Dependent Claim
19 words
A structural member according to claim 10, wherein said polyvinyl alcohol has a degree of hydrolysis of from 75%-95%.
Claim 15
Dependent Claim
18 words
A structural member according to claim 10, wherein said polyvinyl alcohol has a degree of hydrolysis of 87%-91%.
Claim 16
Dependent Claim
25 words
A structural member according to claim 10, wherein said foam has a density of from about 2 lbs to about 20 lbs per cubic foot.
Claim 17
Dependent Claim
20 words
A structural member according to claim 10, wherein said slurry includes an asphalt-wax emulsion to render said gypsum board water-resistant.
Claim 18
Dependent Claim
51 words
A structural member according to claim 10, wherein said foam is formed by adding dry powdered polyvinyl alcohol to said water at ambient temperature to form a foaming mixture, and passing the mixture through a foaming apparatus, whereby said polyvinyl alcohol becomes dissolved in said water and a foam is formed.
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) | 1988-05-20 | 1988-11-19 | 1989-05-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-05-20 | 1992-11-19 | 1993-05-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-05-20 | 1996-11-19 | 1997-05-21 | $7700.00 | Window Closed / Lapsed |