"Multilayer Film"

Abstract

The present invention relates to a multilayer film coextruded from an aliphatic polycarbonate and polylactic acid-based polymer and a method for producing the same. According to the present invention, a multilayer film having excellent adhesive property can be manufactured even without a separate adhesive layer.

1 . A multilayer film, in which at least one aliphatic polycarbonate layer containing aliphatic polycarbonate and at least one polylactic acid-based polymer layer containing polylactic acid-based polymer are laminated in at least two layers. 
     
     
         2 . The multilayer film of  claim 1 , wherein the multilayer film is laminated by coextrusion. 
     
     
         3 . The multilayer film of  claim 2 , wherein the coextrusion is performed by melt extruding the aliphatic polycarbonate at 120 to 210° C. and the polylactic acid-based polymer at 180 to 250° C. and then performing coextrusion using a T-die, blown, or tubular type of extruder. 
     
     
         4 . The multilayer film of  claim 2 , wherein the multilayer film is uniaxially or biaxially stretched at 60 to 90° C. with a stretch ratio of 2 to 6 times. 
     
     
         5 . The multilayer film of  claim 4 , wherein the multilayer film has a shrinkage ratio of 5 to 60% when submerged in a warm water bath at 70 to 100° C. for 30 seconds, after it is uniaxially or biaxially stretched. 
     
     
         6 . The multilayer film of  claim 1 , wherein the polylactic acid-based polymer layer containing the polylactic acid-based polymer is laminated on one surface of the aliphatic polycarbonate layer containing the aliphatic polycarbonate or the polylactic acid-based polymer layers containing the polylactic acid-based polymer are laminated on both surfaces of the aliphatic polycarbonate layer containing the aliphatic polycarbonate. 
     
     
         7 . The multilayer film of  claim 1 , wherein the aliphatic polycarbonate is polycarbonate copolymer or terpolymer obtained by reaction of carbon dioxide and one or more epoxide compounds, which are selected from the group consisting of (C2-C10) alkylene oxide substituted or unsubstituted with halogen or alkoxy; (C4-C20) cycloalkylene oxide substituted or unsubstituted with halogen or alkoxy; and (C8-C20) styrene oxide substituted or unsubstituted with halogen alkoxy, alkyl, or aryl. 
     
     
         8 . The multilayer film of  claim 1 , wherein The aliphatic polycarbonate copolymer has a glass transition temperature (Tg) of 0 to 40° C., and the terpolymer has a glass transition temperature (Tg) of 0 to 110° C. 
     
     
         9 . The multilayer film of  claim 1 , wherein the aliphatic polycarbonate is polypropylene carbonate. 
     
     
         10 . The multilayer film of  claim 1 , wherein the polylactic acid-based polymer has an L-lactic acid content of 80 wt % or more.