Claims
- 1. A method of purifying a biodegradable aliphatic polyester produced without using a catalyst and separated out and collected after polymerization reaction, comprising about 50 to 100 mole percent of lactic acid and about 50 to 0 mole percent of glycolic acid, having a weight average molecular weight of about 3,000 to 50,000 as determined by gel permeation chromatography with a polystyrene standard and containing oligomers having a molecular weight up to 1,000 as determined by gel permeation chromatography with a polystyrene standard, said method comprising:
- (a) dissolving, in 100 parts by volume of a water-soluble organic solvent, a crude biodegradable aliphatic polyester which contains said oligomers to produce a solution,
- (b) gradually adding 50 to 150 parts by volume of water to the solution with stirring,
- (c) recovering a resulting precipitate or oil layer, and
- (d) washing the recovered precipitate or oil layer with water to obtain a purified biodegradable aliphatic polyester containing equal to or less than 3% by weight of oligomers.
- 2. The method according to claim 1, wherein both lactic acid and glycolic acid are present in the biodegradable aliphatic polyester.
- 3. The method according to claim 1, wherein the water-soluble organic solvent is a member selected from the group consisting of acetone, tetrahydrofuran, dioxane, dimethylformamide and dimethylsulfoxide.
- 4. The method according to claim 3, wherein the readily water-soluble organic solvent is acetone.
Priority Claims (1)
Number |
Date |
Country |
Kind |
2-098510 |
Apr 1990 |
JPX |
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Parent Case Info
This application is a continuation of United States application Ser. No. 07/684,270 filed Apr. 12, 1991, now abandoned.
US Referenced Citations (6)
Foreign Referenced Citations (6)
Number |
Date |
Country |
0026599 |
Apr 1981 |
EPX |
0145240 |
Jun 1985 |
EPX |
0190833 |
Aug 1986 |
EPX |
0202065 |
Nov 1986 |
EPX |
0283925 |
Sep 1988 |
EPX |
2491351 |
Apr 1982 |
FRX |
Continuations (1)
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Number |
Date |
Country |
Parent |
684270 |
Apr 1991 |
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