Biodegradable plastic composition, biodegradable plastic shaped body and method of producing same

• US 5,124,371 A
• Filed: 11/13/1990
• Issued: 06/23/1992
• Est. Priority Date: 11/14/1989
• Status: Expired due to Fees

• Current Assignee: Director-General of the Agency of Industrial Science and Technology, the Ministry of International Trade and Industry of Japan (Government of Japan), JSP Corporation (Mitsubishi Electric Corporation)
• Original Assignee: Director-General of the Agency of Industrial Science and Technology, the Ministry of International Trade and Industry of Japan (Government of Japan), JSP Corporation (Mitsubishi Electric Corporation)
• Inventors: Iwamoto, Akira, Tokiwa, Yutaka, Takeda, Kiyoshi
• Primary Examiner(s): Michl, Paul R.
• Assistant Examiner(s): MERRIAM, ANDREW EDWIN
• Application Number:
  US07/611,558
• Time in Patent Office: 588 Days
• Field of Search: 523/124, 523/125, 525/411, 525/415, 525/450
• US Class Current: 523/124
• CPC Class Codes: C08L 67/04 Polyesters derived from hydroxycarboxylic acids, e.g. lactones C08L67/06 takes precedence

Abstract

A biodegradable plastic composition is disclosed which includes a polycaprolactone and a poly-β-hydroxybutyrate. Disclosed also is a biodegradable plastic shaped body formed of such a composition. The shaped body may be produced by melt-mixing a blend of a polycaprolactone, a poly-β-hydroxybutyrate and a copolymerization catalyst to copolymerize a portion of the polycaprolactone with a portion of the poly-β-hydroxybutyrate, thereby to obtain a caprolactone/β-hydroxybutyric acid copolymer-containing melt, which is subsequently shaped into a desired form.

Claims

1. A biodegradable plastic composition comprising at least 70% by weight of a blend of a polycaprolactone and a poly-β

-hydroxybutyrate and 5-30% by weight of a copolymer of caprolactone and β

-hydroxybutyric acid, based on the total weight of said polycaprolactone, said poly-β

-hydroxybutyric acid and said copolymer.

2. The composition as claimed in claim 1, wherein said polycaprolactone and poly-β

-hydroxybutyrate have number average molecular weights of 1,000-120,000 and 10,000-1,000,000, respectively.

3. The composition as claimed in claim 1, wherein the weight ratio of said polycaprolactone to said poly-β

-hydroxybutyrate is 9;

1 to 2;

8.

4. The composition as claimed in claim 1, wherein said copolymer has a molar ratio of caprolactone to β

-hydroxybutyric acid of 2;

8 to 8;

2.

5. The composition as claimed in claim 1, wherein said copolymer has a melting point of 80°

-160°

C.

6. A biodegradable plastic shaped body formed of a mixture containing a copolymer of caprolactone and β

-hydroxybutyric acid and at least 70% by weight of a blend of a polycaprolactone and a poly-β

-hydroxybutyrate.

7. A method of producing a shaped body formed of a biodegradable plastic material, comprising the steps of:

providing a blend of a polycaprolactone, a poly-β

-hydroxybutyrate and a copolymerization catalyst effective to compolymerize said polycaprolactone with said poly-β

-hydroxybutyrate;

mixing said blend at a temperature and for a period of time sufficient to melt said polycaprolactone and said poly-β

-hydroxybutyrate and to copolymerize a portion of said polycaprolactone with a portion of said poly-β

-hydroxybutyrate, thereby to obtain 5-30 wt. % of a caprolactone/β

-hydroxybutyric acid copolymer in a melt in admixture with the remaining polycaprolactone and poly-β

-hydroxybutyrate; and

shaping said melt into a desired form.

8. The method as claimed in claim 7, wherein said mixing and shaping steps are effected with an extruder.