Biodegradable copolymers

Abstract

The present invention relates to biodegradable PHA copolymers comprising at least two randomly repeating monomer units. The present invention further relates to a plastic article comprising a biodegradable copolymer, wherein the biodegradable copolymer comprises at least two randomly repeating monomer units (RRMU) wherein the first RRMU has the structure ##STR1## wherein R 1 is H, or C 1 or C 2 alkyl, and n is 1 or 2; the second RRMU has the structure ##STR2## wherein R 2 is a C 4 -C 19 alkyl or alkenyl; and wherein at least 50% of the RRMUs have the structure of the first RRMU. The present invention further relates to an absorbent article comprising a liquid pervious topsheet, a liquid impervious backsheet comprising a film comprising a PHA of the present invention and an absorbent core positioned between the topsheet and the backsheet.

What is claimed is: 
     
       1. A biodegradable copolymer comprising at least two randomly repeating monomer units wherein the first randomly repeating monomer unit has the structure ##STR14## wherein R 1  is H, or C 1  or C 2  alkyl, and n is 1 or 2; the second randomly repeating monomer unit has the structure ##STR15## wherein .[.when R 1  is C 1  or C 2  and n is 1, R 2  is a C 12  -C 19  alkyl or alkenyl; when R 1  is C 1  or C 2  and n is 2, R 2  is a C 4  -C 19  alkyl or alkenyl; and when R 1  is H and n is 1 or 2 ,.]. R 2  is a .[.C 4-C19  .]. .Iadd.C 4  -C 19  .Iaddend.alkyl or alkenyl; and wherein at least 50% of the randomly repeating monomer units have the structure of the first randomly repeating monomer unit. 
     
     
       2. The biodegradable copolymer of claim 1, wherein R 1  is a C 1  or C 2  alkyl and n is 1. 
     
     
       3. The biodegradable copolymer of claim 1, wherein R 1  is H and n is 2. 
     
     
       4. A biodegradable copolymer comprising at least three randomly repeating monomer units wherein the first randomly repeating monomer unit has the structure ##STR16## wherein R 1  is H, or C 1  or C 2  alkyl, and n is 1 or 2; the second randomly repeating monomer unit has the structure ##STR17## wherein R 2  is a C 4  -C 19  alkyl or alkenyl; the third randomly repeating monomer unit has the structure ##STR18## wherein R 3  is H, or a C 1  -C 19  alkyl or alkenyl; and m is 1 or 2; wherein at least 50% of the randomly repeating monomer units have the structure of the first randomly repeating monomer unit; and wherein the third randomly repeating monomer unit is not the same as the first randomly repeating monomer unit or the second randomly repeating monomer unit. 
     
     
       5. The biodegradable copolymer of claim 4, wherein R 1  is a C 1  or C 2  alkyl and m is 2. 
     
     
       6. The biodegradable copolymer of claim 4, wherein R 1  is H and m is 2. .Iadd. 
     
     
       7.  The biodegradable copolymer of claim 1, wherein R 2  is C 4  -C 7 . .Iaddend..Iadd.8. The biodegradable copolymer of claim 7, wherein R 2  is C 5 . .Iaddend..Iadd.9. The biodegradable copolymer of claim 7, wherein R 2  is C 7 . .Iaddend..Iadd.10. The biodegradable copolymer of claim 1, wherein R 2  is C 8  -C 11 . .Iaddend..Iadd.11. The biodegradable copolymer of claim 10, wherein R 2  is C 9 . .Iaddend..Iadd.12. The biodegradable copolymer of claim 1, wherein R 2  is C 12  -C 19 . .Iaddend..Iadd.13. The biodegradable copolymer of claim 8, wherein R 1  is C 1  alkyl and n is 1. .Iaddend..Iadd.14. The biodegradable copolymer of claim 12, wherein R 1  is C 1  alkyl and n is 1. .Iaddend..Iadd.15. The biodegradable copolymer of claim 4, wherein R 2  is C 4  -C 7 . .Iaddend..Iadd.16. The biodegradable copolymer of claim 15, wherein R 2  is C 5 . .Iaddend..Iadd.17. The biodegradable copolymer of claim 15, wherein R 2  is C 7 . .Iaddend..Iadd.18. The biodegradable copolymer of claim 4, wherein R 2  is C 8  -C 11 . .Iaddend..Iadd.19. The biodegradable copolymer of claim 18, wherein R 2  is C 9 . .Iaddend..Iadd.20. The biodegradable copolymer of claim 4, wherein R 2  is C 12  -C 19 . .Iaddend..Iadd.21. The biodegradable copolymer of claim 16, wherein R 1  is C 1  alkyl and n is 1. .Iaddend..Iadd.22. The biodegradable copolymer of claim 20, wherein R 1  is C 1  alkyl and n is 1. .Iaddend.