Claims
- 1. 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.
- 2. A process according to claim 1, wherein the aldehyde is formaldehyde or glutaraldehyde.
- 3. A process according to claim 2, wherein the formaldehyde is in the form of an aqueous solution of formaldehyde stabilized with methanol.
- 4. A process according to claim 3, wherein the formaldehyde concentration is about 37% by weight.
- 5. 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.
- 6. A process according to claim 1, wherein the pH of the salt solution is from about 1.5 to about 3.0.
- 7. A process according to claim 6, wherein said pH is from about 1.9 to 2.3.
- 8. A process according to claim 1, wherein the salt solution is a sodium sulfate solution.
- 9. The process according to claim 8, wherein the sodium sulfate concentration is about 16 weight percent in the aqueous solution.
- 10. A process according to claim 1, wherein the salt solution is heated to a temperature between about 85.degree. F. and 140.degree. F.
- 11. A process according to claim 1, wherein the polyvinyl alcohol has a weight average molecular weight of at least 20,000.
- 12. 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.
- 13. A process according to claim 12, wherein the polyvinyl alcohol is from about 80 to 95 percent hydrolyzed.
- 14. A process according to claim 2, wherein the weight ratio of formaldehyde to polyvinyl alcohol is about 0.0095:1.
- 15. A process according to claim 2, wherein the weight ratio of glutaraldehyde to polyvinyl alcohol is about 0.0016:1.
- 16. 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.
- 17. A process according to claim 1, wherein the drying is done in a continuous dryer.
- 18. A process according to claim 1, wherein the drying is done in a batch dryer.
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a continuation-in-part of U.S. Application Ser. No. 423,798, filed Sept. 27, 1982, now abandoned.
US Referenced Citations (1)
Number |
Name |
Date |
Kind |
4240915 |
Block |
Dec 1982 |
|
Foreign Referenced Citations (2)
Number |
Date |
Country |
2073228 |
Oct 1981 |
GBX |
2074636 |
Nov 1981 |
GBX |
Continuation in Parts (1)
|
Number |
Date |
Country |
Parent |
423798 |
Sep 1982 |
|