CELLULOSE ACETATE BUTYRATE SEMIPERMEABLE MEMBRANES AND THEIR PRODUCTION

• US 3,607,329 A
• Filed: 04/22/1969
• Issued: 09/21/1971
• Est. Priority Date: 04/22/1969
• Status: Expired due to Term

• Current Assignee: Serop Manjikian
• Original Assignee: Serop Manjikian
• Inventors: MANJIKIAN SEROP
• Application Number:
  US04/818,397
• Time in Patent Office: 882 Days
• US Class Current: 106/170.16
• CPC Class Codes: B01D 2323/12 Specific ratios of components used
• CPC Class Codes: B01D 67/0011 Casting solutions therefor
• CPC Class Codes: B01D 71/18 Mixed esters, e.g. cellulose acetate-butyrate

Abstract

Semipermeable membranes are produced by casting a solution consisting essentially of cellulose acetate butyrate, triethyl phosphate, a flux promoter and an organic solvent into a film, and subsequently gelling the film by immersion in water. The membranes of the invention find particular utility in separation of solutes from solutions by osmosis or reverse osmosis.

Claims

2. A method according to claim 1 in which the cellulose acetate butyrate in (a) contains about 17 percent combined butyryl groups and about 29.5 percent combined acetyl groups.

3. A method according to claim 1 in which the cellulose acetate butyrate in (a) has a rated viscosity between about 10 and 50 seconds by ASTM method D-1343-T.

4. A method according to claim 1 in which the flux promotor in (c) comprises in combination glycerol in amount from about 1.5 percent to about 6 percent and n-propanol in amount from about 4.5 percent to about 18 percent.

5. A method according to claim 1 in which the flux promoter in (c) comprises in combination glycerol in amount from about 1.5 percent to about 6 percent and lactic acid in amount From about 4.5 percent to about 18 percent.

6. A method according to claim 1 in which the organic solvent in (d) is acetone.

7. A method according to claim 1 in which the casting solution comprises:

a. cellulose acetate butyrate of about 17 percent combined butyryl groups and about 29.5 percent combined acetyl groups and viscosity about 15 seconds by ASTM method D-1343-54T, in amount about 22 percent;

b. Triethyl phosphate in amount about 25 percent;

c. glycerol in amount about 2 percent;

d. n-propanol in about 6 percent; and

e. acetone in amount about 45 percent.

8. A method according to claim 1 in which a time up to about 90 seconds is allowed for removal by evaporation of part of the volatile constituents of said film before immersion in water.

9. A method according to claim 8 in which a time of about 60 seconds is allowed for removal by evaporation of part of the volatile constituents of said film before immersion in water.

10. A semipermeable membrane made by the method of claim 1.