US4472552A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Continuous process for making solid, free-flowing water dispersible PVA-aldehyde reaction product
Assignee: WR Grace and Co
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Filing: 1983-11-21
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Granted: 1984-09-18
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Expires: 2003-11-21
Abstract
Abstract A polyvinyl alcohol-aldehyde reaction product is produced continuously in a rotating contactor by contacting solid particles of the polyvinyl alcohol with the aldehyde in an acidic aqueous salt solution. The product can be dried and then sieved to remove oversize particles. A preferred aldehyde is either formaldehyde or glutaraldehyde which reacts with the polyvinyl alcohol to produce a reaction product that can be used as a fluid loss control agent in oil fields.
Inventors
- 👤 John J. Blouin
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 14:07
CPC Classifications
B; B01; B01J; B01J19/00; B01J19/28; C; C08; C08F; C08F8/00; C08F8/48; B01J2208/00; B01J2208/00008; B01J2208/00017; B01J2208/0053; B01J2208/00592; C08F2810/00; C08F2810/20
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
70 words
A process for the continuous production of a polyvinyl alcohol-aldehyde reaction product comprising (a) adding to a rotating continuous reactor to form a mixture (i) solid particles of polyvinyl alcohol, (ii) an aldehyde, and (iii) an aqueous salt solution adjusted to have an acidic pH; (b) mixing the mixture of step (a) in the reactor until a polyvinyl alcohol-aldehyde reaction product is obtained; and (c) drying the polyvinyl alcohol-aldehyde material.
Claim 2
Dependent Claim
70 words
A process for the continuous production of a polyvinyl alcohol-aldehyde reaction product comprising (a) adding to a rotating continuous reactor to form a mixture (i) solid particles of polyvinyl alcohol, (ii) an aldehyde, and (iii) an aqueous salt solution adjusted to have an acidic pH; (b) mixing the mixture of step (a) in the reactor until a polyvinyl alcohol-aldehyde reaction product is obtained; and (c) drying the polyvinyl alcohol-aldehyde material.
Claim 3
Dependent Claim
13 words
A process according to claim 1, wherein the aldehyde is formaldehyde or glutaraldehyde.
Claim 4
Dependent Claim
22 words
A process according to claim 2, wherein the formaldehyde is in the form of an aqueous solution of formaldehyde stabilized with methanol.
Claim 5
Dependent Claim
15 words
A process according to claim 3, wherein the formaldehyde concentration is about 37% by weight.
Claim 6
Dependent Claim
30 words
A process according to claim 2, wherein the formaldehyde is added as paraformaldehyde and the amount added is less than the stoichiometric amount needed to react with the polyvinyl alcohol.
Claim 7
Dependent Claim
20 words
A process according to claim 1, wherein the pH of the salt solution is from about 1.5 to about 3.0.
Claim 8
Dependent Claim
15 words
A process according to claim 6, wherein said pH is from about 1.9 to 2.3.
Claim 9
Dependent Claim
15 words
A process according to claim 1, wherein the salt solution is a sodium sulfate solution.
Claim 10
Dependent Claim
20 words
The process according to claim 8, wherein the sodium sulfate concentration is about 16 weight percent in the aqueous solution.
Claim 11
Dependent Claim
22 words
A process according to claim 1, wherein the salt solution is heated to a temperature between about 85° F. and 140° F.
Claim 12
Dependent Claim
20 words
A process according to claim 1, wherein the polyvinyl alcohol has a weight average molecular weight of at least 20,000.
Claim 13
Dependent Claim
30 words
A process according to claim 1, wherein the polyvinyl alcohol has a weight average molecular weight of from about 90,000 to 200,000 and is at least about 75 percent hydrolyzed.
Claim 14
Dependent Claim
18 words
A process according to claim 12, wherein the polyvinyl alcohol is from about 80 to 95 percent hydrolyzed.
Claim 15
Dependent Claim
18 words
A process according to claim 2, wherein the weight ratio of formaldehyde to polyvinyl alcohol is about 0.0095:1.
Claim 16
Dependent Claim
18 words
A process according to claim 2, wherein the weight ratio of glutaraldehyde to polyvinyl alcohol is about 0.0016:1.
Claim 17
Dependent Claim
32 words
A process according to claim 1, wherein the salt solution is a sodium sulfate solution and the sodium sulfate solution and aldehyde are first premixed before being mixed with the polyvinyl alcohol.
Claim 18
Dependent Claim
15 words
A process according to claim 1, wherein the drying is done in a continuous dryer.
Claim 19
Dependent Claim
15 words
A process according to claim 1, wherein the drying is done in a batch dryer.
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) | 1987-09-18 | 1988-03-19 | 1988-09-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-09-18 | 1992-03-19 | 1992-09-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-09-18 | 1996-03-19 | 1996-09-18 | $7700.00 | Window Closed / Lapsed |