US4785049A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Forming clear gel and transparent film by reacting alumina hydrate with vinyl alcohol-vinyl acetate copolymer
Assignee: Alcoa Corp
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Filing: 1987-07-27
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Granted: 1988-11-15
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Expires: 2007-07-27
Abstract
Abstract A stable gel is formed by reacting alumina hydrate sol and a vinyl alcohol-vinyl acetate copolymer in an aqueous solution having pH less than about 7 to form a polymeric sol and then transforming the sol to a gel. The copolymer preferably comprises polyvinyl acetate that is about 85-99% hydrolyzed. The gel is drawn into a thin layer and water is removed to form a thin, substantially crack-free film. The film makes a stable, generally transparent insulating material.
Inventors
- 👤 Willy M. Balaba
- 👤 Gary J. DiFranco
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 02:15
CPC Classifications
C; C08; C08K; C08K3/00; C08K3/18; C08K3/20; C08K3/22
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
105 words
A method for preparing a stable gel comprising alumina hydrate combined with a water-soluble partially hydrolized polyvinyl acetate polymer, said method comprising (a) preparing a sol comprising a colloidal dispersion of alumina hydrate in an aqueous medium, (b) mixing said sol with a water-soluble partially hydrolyzed polyvinyl acetate polymer comprising about 85-99% vinyl alcohol groups, (c) reacting said alumina hydrate with said copolymer in an aqueous solution having a pH of less than about 7, thereby to form a polymeric sol comprising alumina hydrate combined with the said polymer, and (d) transforming the polymeric sol to a stable gel by eliminating the aqueous dispersion medium.
Claim 2
Independent Claim
105 words
A method for preparing a stable gel comprising alumina hydrate combined with a water-soluble partially hydrolized polyvinyl acetate polymer, said method comprising (a) preparing a sol comprising a colloidal dispersion of alumina hydrate in an aqueous medium, (b) mixing said sol with a water-soluble partially hydrolyzed polyvinyl acetate polymer comprising about 85-99% vinyl alcohol groups, (c) reacting said alumina hydrate with said copolymer in an aqueous solution having a pH of less than about 7, thereby to form a polymeric sol comprising alumina hydrate combined with the said polymer, and (d) transforming the polymeric sol to a stable gel by eliminating the aqueous dispersion medium.
Claim 3
Dependent Claim
34 words
The method as claimed in claim 1 further comprising, before transforming step (d), (e) adding to the sol a water-soluble plasticizer selected from the group consisting of diethylene glycol, polyethylene glycol and mixtures thereof.
Claim 4
Dependent Claim
13 words
The method as claimed in claim 2 wherein the plasticizer is diethylene glycol.
Claim 5
Dependent Claim
15 words
The method as claimed in claim 1 wherein the polyvinyl acetate is about 87-97% hydrolyzed.
Claim 6
Dependent Claim
19 words
The method as claimed in claim 1 wherein the molecular weight of the polymer is greater than about 50,000.
Claim 7
Dependent Claim
19 words
The method as claimed in claim 1 wherein the molecular weight of the polymer is greater than about 100,000.
Claim 8
Dependent Claim
24 words
The method as claimed in claim 1 wherein step (a) includes hydrolyzing an aluminum alkoxide in an aqueous acidic solution to form a sol.
Claim 9
Dependent Claim
20 words
The method as claimed in claim 1 wherein step (c) is performed at an elevated temperature of about 50°-100° C.
Claim 10
Dependent Claim
16 words
The method as claimed in claim 1 wherein steps (a) and (b) are performed substantially simultaneously.
Claim 11
Dependent Claim
19 words
The method as claimed in claim 1 wherein step (d) is performed by removing water from the polymeric sol.
Claim 12
Dependent Claim
57 words
The method of claim 2 wherein the polymeric sol of step (c) comprises at least 10 wt. % of the polymer, said method further comprising the formation of a film by (f) drawing the gel into a layer having a thickness of less than about one millimeter, and (g) removing any remaining water from the gel layer.
Claim 13
Dependent Claim
17 words
The method of claim 11 wherein step (g) comprises heating the gel layer at an elevated temperature.
Claim 14
Dependent Claim
26 words
A stable clear gel comprising alumina hydrate combined with a water-soluble partially hydrolyzed polyvinyl acetate polymer, said gel being formed by the method of claim 1.
Claim 15
Dependent Claim
15 words
The gel of claim 11 having at least about 50% light transmission at 500 nm.
Claim 16
Dependent Claim
11 words
A substantially crack-free film formed by the method of claim 11.
Claim 17
Dependent Claim
11 words
A substantially crack-free film formed by the method of claim 12.
Claim 18
Dependent Claim
40 words
A stable gel prepared in an aqueous solution having a pH less than about 7, said gel being the reaction product of an alumina hydrate sol and a water-soluble partially hydrolyzed polyvinyl acetate polymer comprising about 85-99% vinyl alcohol groups.
Claim 19
Dependent Claim
40 words
A stable gel prepared in an aqueous solution having a pH less than about 7, said gel being the reaction product of an alumina hydrate sol and a water-soluble partially hydrolyzed polyvinyl acetate polymer comprising about 85-99% vinyl alcohol groups.
Claim 20
Dependent Claim
98 words
A transparent, thin, crack-free film formed by the steps of (a) forming a polymeric sol by reacting an alumina hydrate sol and a water-soluble partially hydrolyzed polyvinyl acetate polymer in an aqueous solution containing a water-soluble plasticizer and having pH less than 7, wherein said solution contains at least 10 wt. % of a polymer comprising about 85-99% vinyl alcohol groups, (b) transforming the sol to a gel by eliminating the aqueous dispersion medium, (c) drawing the gel into a thin layer, and (d) removing any remaining water from the thin layer, thereby to form a thin film.
Claim 21
Dependent Claim
98 words
A transparent, thin, crack-free film formed by the steps of (a) forming a polymeric sol by reacting an alumina hydrate sol and a water-soluble partially hydrolyzed polyvinyl acetate polymer in an aqueous solution containing a water-soluble plasticizer and having pH less than 7, wherein said solution contains at least 10 wt. % of a polymer comprising about 85-99% vinyl alcohol groups, (b) transforming the sol to a gel by eliminating the aqueous dispersion medium, (c) drawing the gel into a thin layer, and (d) removing any remaining water from the thin layer, thereby to form a thin film.
Claim 22
Dependent Claim
22 words
The film of claim 18 wherein said plasticizer is selected from the group consisting of diethylene glycol, polyethylene glycol and mixtures thereof.
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) | 1991-11-15 | 1992-05-16 | 1992-11-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-11-15 | 1996-05-16 | 1996-11-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-11-15 | 2000-05-16 | 2000-11-15 | $7700.00 | Window Closed / Lapsed |