POLYLACTIC ACID COMPOSITION, FOAM MOLDED ARTICLE THEREOF AND METHOD OF PRODUCING THE SAME

• US 20130203877A1
• Filed: 03/29/2011
• Published: 08/08/2013
• Est. Priority Date: 03/29/2010
• Status: Active Grant

• Current Assignee: Kazunori Tsuda, Kosuke Uchiyama
• Original Assignee: Kosuke Uchiyama
• Inventors: Uchiyama, Kosuke, Tsuda, Kazunori, Suzuki, Tenya
• Granted Patent: US 8,921,434 B2
• Time in Patent Office: Days
• US Class Current: 521/79
• CPC Class Codes: B29C 44/3446 Feeding the blowing agent
• CPC Class Codes: B29C 44/586 with a cavity increasing in size during foaming
• CPC Class Codes: B29C 48/022 characterised by the choice of material
• CPC Class Codes: B29C 48/03 characterised by the shape of the extruded material at extrusion
• CPC Class Codes: B29C 48/37 Gear pumps
• CPC Class Codes: B29C 48/655 having three or more threads
• CPC Class Codes: B29C 48/76 Venting , drying means; Degassing means
• CPC Class Codes: B29K 2067/046 PLA, i.e. polylactic acid or polylactide
• CPC Class Codes: C08G 18/428 Lactides
• CPC Class Codes: C08G 18/6644 having at least three hydroxy groups
• CPC Class Codes: C08G 18/73 acyclic
• CPC Class Codes: C08G 2101/00 Manufacture of cellular products
• CPC Class Codes: C08G 63/08 Lactones or lactides
• CPC Class Codes: C08G 63/88 Post-polymerisation treatment
• CPC Class Codes: C08G 63/91 Polymers modified by chemical after-treatment
• CPC Class Codes: C08J 2201/024 Preparation or use of a blowing agent concentrate, i.e. masterbatch in a foamable composition
• CPC Class Codes: C08J 2201/026 Crosslinking before of after foaming
• CPC Class Codes: C08J 2201/03 Extrusion of the foamable blend
• CPC Class Codes: C08J 2203/08 Supercritical fluid
• CPC Class Codes: C08J 2367/04 Polyesters derived from hydroxy carboxylic acids, e.g. lactones C08J2367/06 takes precedence
• CPC Class Codes: C08J 3/24 : Crosslinking, e.g. vulcanising, of macromolecules mechanical aspects B29C35/00; crosslinking agents C08K
• CPC Class Codes: C08J 9/122 : Hydrogen, oxygen, CO2, nitrogen or noble gases
• CPC Class Codes: C08K 3/26 : Carbonates; Bicarbonates
• CPC Class Codes: C08K 3/34 : Silicon-containing compounds
• CPC Class Codes: C08K 5/29 : Compounds containing one or more carbon-to-nitrogen double bonds
• CPC Class Codes: C08L 67/04 : Polyesters derived from hydroxycarboxylic acids, e.g. lactones C08L67/06 takes precedence

Abstract

An object of the present invention is to inexpensively provide a method and device of producing a high viscosity polylactic acid composition, which composition is appropriate for foam molding having a high expansion ratio and is stable, and a foam molded article having a high expansion ratio formed of said high viscosity polylactic acid composition. A method of producing a polylactic acid foam molded article of the present invention which can achieve the above-described object is characterized by comprising a step of mechanically grinding a polylactic acid composition by applying a shear force, using a device equipped with an injection molding machine (B) or an extrusion molding machine (G), an orifice portion (S) and a foaming mold (P), in a foaming gas atmosphere in the orifice portion (S). The above-described polylactic acid composition is obtained by mechanically grinding polylactic acid, which polylactic acid is cross-linked by polyisocyanate, by applying a shear force in an inert gas atmosphere, said polylactic acid composition obtained by the grinding being characterized by having an MI value of 0.05 or more and 5 or less, which MI value is measured at 190° C. under a load of 21.6 kg in accordance with JIS K7210 (ISO 1133) (FIG. 2).

Claims

1-10. -10. (canceled)

11. A polylactic acid composition obtained by mechanically grinding polylactic acid, which polylactic acid is cross-linked by polyisocyanate, by applying a shear force in supercritical condition of an inert gas, wherein the amount of said polyisocyanate combined is 0.4 to 5% by weight based on polylactic acid, and said polylactic acid composition obtained by the grinding has an MI value of 0.05 or more and 5 or less, which MI value is measured at 190°

C. under a load of 21.6 kg in accordance with JIS K7210 (ISO

     1133).

12. The polylactic acid composition according to claim 11, wherein a number average molecular weight in polystyrene equivalent of said polylactic acid composition obtained by the grinding measured by GPC is less than 1.5 million.

13. The polylactic acid composition according to claim 11, wherein said polyisocyanate is triisocyanate, tetraisocyanate or diisocyanate, or which comprises any of the adduct forms of said polyisocyanates.

14. The polylactic acid composition according to claim 11, which contains 0.5 to 5% by weight of calcium carbonate or talc particle.

15. A foam molded article formed of the polylactic acid composition according to claim 11.

16. The foam molded article according to claim 15, which maintains the shape thereof after 90°

C. hot water is poured into the foam molded article.

18. A method of producing a foam molded article formed of the polylactic acid composition according to claim 11, said method comprising a step of mechanically grinding said polylactic acid composition by applying a shear force, using a device equipped with an injection molding machine (B) or an extrusion molding machine (G),an orifice portion (S) and a foaming mold (P), in supercritical condition of a foaming gas in the orifice portion (S).

19. A foam molded article produced by the production method according to claim 18.

17. A method of producing a polylactic acid composition obtained by mechanically grinding polylactic acid, which polylactic acid is cross-linked by polyisocyanate, by applying a shear force, wherein the amount of said polyisocyanate combined is 0.4 to 5% by weight based on polylactic acid, said grinding is conducted in supercritical condition of an inert gas, and said polylactic acid composition obtained by the grinding has an MI value of 0.05 or more and 5 or less, which MI value is measured at 190°

C. under a load of 21.6 kg in accordance with JIS K7210 (ISO

     1133).