Biodegradable resin film or sheet and process for producing the same

• US 20060257676A1
• Filed: 05/27/2003
• Published: 11/16/2006
• Est. Priority Date: 05/27/2003
• Status: Abandoned Application

• Current Assignee: Asahi Kasei Life & Living Corporation
• Original Assignee: Asahi Kasei Life & Living Corporation
• Inventors: Sukigara, Masayuki, Itada, Mitsuyoshi
• Application Number:
  US10/558,266
• Publication Number:
  US 20060257676A1
• Time in Patent Office: Days
• US Class Current: 428/480
• CPC Class Codes: B29C 55/005 characterised by the choice of materials
• CPC Class Codes: B29K 2105/0088 Blends of polymers
• CPC Class Codes: B29K 2995/006 Bio-degradable, e.g. bioabsorbable, bioresorbable or bioerodible
• CPC Class Codes: C08J 2300/16 Biodegradable polymers
• CPC Class Codes: C08J 2367/04 Polyesters derived from hydroxy carboxylic acids, e.g. lactones C08J2367/06 takes precedence
• CPC Class Codes: C08J 5/18 Manufacture of films or sheets
• CPC Class Codes: C08L 2666/18 Polyesters or polycarbonates according to C08L67/00 - C08L69/00; Derivatives thereof
• CPC Class Codes: C08L 67/02 Polyesters derived from dicarboxylic acids and dihydroxy compounds C08L67/06 takes precedence
• CPC Class Codes: C08L 67/04 Polyesters derived from hydroxycarboxylic acids, e.g. lactones C08L67/06 takes precedence
• CPC Class Codes: Y10T 428/31786 Of polyester [e.g., alkyd, etc.]

Abstract

A biodegradable resin drawn film or biodegradable resin drawn sheet that is excellent in transparency, impact resistance and film re-forming capability (recyclability); and a process for producing the same. In particular, a biodegradable resin drawn film or biodegradable resin drawn sheet composed mainly of a mixture of (A) a biodegradable resin of greater than or equal to 30° C. as a glass transition temperature Tg and (B) a biodegradable resin of less than or equal to 5° C. as a glass transition temperature Tg characterized in that a multiplicity of domains comprising component (B) mainly in the configuration of lamellar or rod-shaped pieces are present in a continuous phase comprising component (A) substantially in parallel to the external surface of the film or sheet; and a process for producing the same.

Claims

1-11. -11. (canceled)

12. A biodegradable resin drawn film or biodegradable resin drawn sheet comprising a mixture comprising (A) a biodegradable resin having a glass transition temperature Tg of greater than or equal to 30°

C. according to the differential scanning calorimetry (JIS-K

     7121) and (B) a biodegradable resin having a glass transition temperature of less than or equal to 5°

C. according to the differential scanning calorimetry (JIS-K

     7121) wherein;

the weight ratio of (A)/(B) is 90/10 to 60/40;

a multiplicity of domains comprising component (B) in the configuration of lamellar or rod-shaped pieces are present in a continuous phase comprising component (A);

said lamellar or rod-shaped pieces are substantially in parallel to the external surface of the film or sheet; and

the thickness (D) of said lamellar or rod-shaped pieces is less than 150 nm per piece.

13. The biodegradable resin drawn film or biodegradable resin drawn sheet according to claim 12, wherein the component (A) and/or (B) is a biodegradable polyester.

14. The biodegradable resin drawn film or biodegradable resin drawn sheet according to claim 12, wherein the component (A) is a polylactic acid polymer derived mainly from L-lactic acid and/or D-lactic acid.

15. The biodegradable resin drawn film or biodegradable resin drawn sheet according to claim 12, wherein a weight ratio (A)/(B) is 90/10 to 75/25.

16. The biodegradable resin drawn film or biodegradable resin drawn sheet according to claim 14, wherein the component (A) comprises a composition prepared by mixing (A1) a crystalline polylactic acid having an optical purity OP (A1) and (A2) an amorphous polylactic acid having an optical purity OP (A2) and which composition satisfies the following equations (1) and (2):

80%≦

OP(A1)≦

100%, 0%≦

OP(A2)<

80%  

 

(1)
20%≦

[A2]/([A1]+[A2])≦

100%  

 

(2)

wherein [A1]+[A2]=100%, [A1] represents a weight ratio (unit;

%) of the crystalline polylactic acid (A1), and [A2] represents a weight ratio (unit;

%) of the amorphous polylactic acid (A2).

17. The biodegradable resin drawn film or biodegradable resin drawn sheet according to claim 13, wherein the component (B) is at least one polycondensed aliphatic polyester derived from an aliphatic dicarboxylic acid and an aliphatic diol or at least one polycondensed aliphatic aromatic polyester derived from an aromatic dicarboxylic acid, an aliphatic dicarboxylic acid and an aliphatic diol.

18. The biodegradable resin drawn film or biodegradable resin drawn sheet according to claim 17, wherein the polycondensed aliphatic polyester or the polycondensed aliphatic aromatic polyester is selected from the group consisting of polyethylene adipate, polypropylene adipate, polybutylene adipate, polyhexene adipate, polyethylene succinate, polypropylene succinate, polybutylene succinate, polybutylene succinate adipate, polyethylene terephthalate succinate and polybutylene adipate terephthalate.

19. The biodegradable resin drawn film or biodegradable resin drawn sheet according to claim 12, which has a haze value measured by using a hazemeter (ASTM-D 1003-95) of less than 5%.

20. A composite film or composite sheet, comprising at least one layer which is a biodegradable resin drawn film or biodegradable resin drawn sheet according to any one of claims 12 to 19.

21. A process for producing a biodegradable resin drawn film or biodegradable resin drawn sheet which comprises the steps of melt extruding a mixture comprising two types of the biodegradable resins having glass transition temperatures Tg which differ by greater than or equal to 25°

C. according to the differential scanning calorimetry (JIS-K

     7121), and drawing in at least one direction until the thickness of the ultimate film or sheet becomes greater than or equal to 1/200 times and less than or equal to 1/40 times the height of the die lip opening (in other words, until the area of the ultimate film or sheet becomes greater than or equal to 40 times and less than or equal to 200 times as large as the area of the film or sheet just extruded from the die lip).

22. The process for producing a biodegradable resin drawn film or biodegradable resin drawn sheet according to claim 21, wherein after the mixture comprising two types of the biodegradable resins is melt extruded from the die lip and drawn in the molten state in at least one direction until the thickness becomes greater than or equal to 1/20 times and less than or equal to ½

times the height of the die lip opening (in other words, until the area becomes greater than or equal to 2 times and less than or equal to 20 times as large as the area of the film or sheet just extruded from the die lip), the film or sheet is quenched to make it substantially amorphous and then drawn in at least one direction.

23. The process for producing a biodegradable resin drawn film or biodegradable resin drawn sheet according to claim 21 or 22, wherein the mixture of two types of biodegradable resins is a mixture comprising (A) a biodegradable resin having a glass transition temperature Tg of greater than or equal to 30°

C. according to the differential scanning calorimetry (JIS-K

     7121) and (B) a biodegradable resin having a glass transition temperature of less than or equal to 5°

C. according to the differential scanning calorimetry (JIS-K

     7121) and the weight ratio of (A)/(B) is 90/10 to 60/40.