Abstract Polyvinyl acetals are prepared by de-esterifying a polyvinyl ester in solution in methanol containing an alkali metal hydroxide to produce a suspension of polyvinyl alcohol particles in methanol and methyl ester, acidifying the suspension with sulphuric acid, adding an aldehyde and reacting to form the acetal. Specified esters are polyvinyl acetate, propionate and butyrate. Specified aldehydes are butyraldehyde, isobutyraldehyde, propionaldehyde and valeraldehyde. Specified hydroxides are sodium and potassium hydroxides. The de-esterification may be carried out at from room to the reflux temperature and the acetalization preferably at the reflux temperature. Both reactions may be conducted under superatmospheric pressures. The excess sulphuric acid may be neutralized, e.g. with sodium hydroxide, and the acetal precipitated by mixing the solution with water and washed in a large excess of water.
Inventors
👤 Richard H Cahill
👤 Fazio Charles A De
👤 John C Lukman
Bibliographic Details
Application Number—
JurisdictionUS
Data Sourcegoogle_patents
Last Synchronized2026-11-04 09:02
CPC Classifications
C; C08; C08F; C08F8/00; C08F8/28
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
149 words
PROCESS FOR THE PRODUCTION OF POLYVINYL BUTYRAL, WHICH COMPRISES DE-ESTERIFYING POLYVINYL ACETATE IN SOLUTION IN ESSENTIALLY ANHYDROUS METHANOL CONTAINING SODIUM HYDROXIDE UNTIL AT LEAST 98% OF THE ACETATE GROUPS HAVE BEEN CONVERTED TO HYDROXYL GROUPS TO PRODUCE A SUSPEN SSION OF PARTICLES OF POLYVINYL ALCOHOL IN A LIQUID COMPRIDING METHANOL AND METHYL ACETATE, ADDING TO SAID SUSPENSION SULFURIC ACID IN METHANOL AND THEN BUTYRALDEHYDE IN AN AMOUNT SUFFICIENT TO PROVIDE 0.4 TO 0.6 MOLECULE OF BUTYRALDEHYDE PER ALCOHOLIC HYDROXYL GROUP OF THE POLYVINYL ALCOHOL, THE AMOUNT OF SULFURIC ACID BEING SUFFICIENT TO ACIDIFY SAID POLYVINYL AND REACTING SAID BUTYRALDEHYDE AND SAID POLYVINYL ALCOHOL AT A TEMPERATURE OF AT LEAST 64*C. TO PRODUCE A SOLUTION OF POLYVINYL BUTYRAL HAVING A BUTYRAL, CONTENT OF AT LEAST ABOUT 76% CALCULATED AS POLYVINYL BUTYRAL, THE TOTAL PERIOD FOR SAID DE-ESTERIFICATION STEP AND SAID REACTION WITH BUTYRALDEHYDE TAKING NOT MORE THAN ABOUT TWO HOURS
Claim 2
Dependent Claim
149 words
PROCESS FOR THE PRODUCTION OF POLYVINYL BUTYRAL, WHICH COMPRISES DE-ESTERIFYING POLYVINYL ACETATE IN SOLUTION IN ESSENTIALLY ANHYDROUS METHANOL CONTAINING SODIUM HYDROXIDE UNTIL AT LEAST 98% OF THE ACETATE GROUPS HAVE BEEN CONVERTED TO HYDROXYL GROUPS TO PRODUCE A SUSPEN SSION OF PARTICLES OF POLYVINYL ALCOHOL IN A LIQUID COMPRIDING METHANOL AND METHYL ACETATE, ADDING TO SAID SUSPENSION SULFURIC ACID IN METHANOL AND THEN BUTYRALDEHYDE IN AN AMOUNT SUFFICIENT TO PROVIDE 0.4 TO 0.6 MOLECULE OF BUTYRALDEHYDE PER ALCOHOLIC HYDROXYL GROUP OF THE POLYVINYL ALCOHOL, THE AMOUNT OF SULFURIC ACID BEING SUFFICIENT TO ACIDIFY SAID POLYVINYL AND REACTING SAID BUTYRALDEHYDE AND SAID POLYVINYL ALCOHOL AT A TEMPERATURE OF AT LEAST 64*C. TO PRODUCE A SOLUTION OF POLYVINYL BUTYRAL HAVING A BUTYRAL, CONTENT OF AT LEAST ABOUT 76% CALCULATED AS POLYVINYL BUTYRAL, THE TOTAL PERIOD FOR SAID DE-ESTERIFICATION STEP AND SAID REACTION WITH BUTYRALDEHYDE TAKING NOT MORE THAN ABOUT TWO HOURS