Pliable plastic film and container using the same

Abstract

A pliable plastic film according to the present invention comprises a heat sealable sealing layer, wherein the sealing layer is made of a mixture of a propylene-α-olefin random copolymer having a crystalline melting point T m of 135 to 145° C. and a polypropylene (PP) homopolymer having a crystalline melting point T m of higher than 160° C.

1 . A pliable plastic film comprising a heat sealable sealing layer, wherein the sealing layer is made of a mixture of a propylene-α-olefin random copolymer having a crystalline melting point T m  of 135 to 145° C. and a polypropylene homopolymer having a crystalline melting point T m  of higher than 160° C. 
   
   
       2 . The pliable plastic film according to  claim 1 , wherein a content ratio of the polypropylene homopolymer is from 5 to 30% by weight based on the mixture. 
   
   
       3 . The pliable plastic film according to  claim 1 , wherein the polypropylene homopolymer has a melting point of more than 160° C. and not more than 170° C. and an isotactic pentad fraction of not less than 0.97. 
   
   
       4 . The pliable plastic film according to  claim 2 , wherein the polypropylene homopolymer has a melting point of more than 160° C. and not more than 170° C. and an isotactic pentad fraction of not less than 0.97. 
   
   
       5 . The pliable plastic film according  claim 1 , further comprising a layer containing polypropylene formed on a surface of the sealing layer. 
   
   
       6 . The pliable plastic film according to  claim 1 , further comprising a first flexible layer formed on a surface of the sealing layer, a reinforcing layer formed on a surface of the first flexible layer, a second flexible layer formed on a surface of the reinforcing layer, and an outermost layer formed on a surface of the second flexible layer, wherein
 the first flexible layer is made of a mixture of at least one kind of polymer selected from the group consisting of a propylene-α-olefin random copolymer, a propylene-α-olefin block copolymer and a syndiotactic polypropylene, and an ethylene-α-olefin copolymer elastomer, and the content ratio of the ethylene-α-olefin copolymer elastomer is from 30 to 50% by weight based on an entire of the first flexible layer,   the reinforcing layer is made of at least one kind of polymer selected from the group consisting of a polypropylene homopolymer, a propylene-α-olefin random copolymer, a propylene-α-olefin block copolymer and a cyclo olefin polymer,   the second flexible layer is made of a mixture of at least one kind of polymer selected from the group consisting of a propylene-α-olefin random copolymer, a propylene-α-olefin block copolymer and a syndiotactic polypropylene, and an ethylene-α-olefin copolymer elastomer, and the content ratio of the ethylene-α-olefin copolymer elastomer is from 30 to 50% by weight based on an entire of the second flexible layer, and   the outermost layer is made of at least one kind of polymer selected from the group consisting of a polypropylene homopolymer, a propylene-α-olefin random copolymer and a propylene-α-olefin block copolymer.   
   
   
       7 . The pliable plastic film according to  claim 6 , wherein the thicknesses of the first flexible layer and the second flexible layer respectively account for 30 to 40% of an entire of the film thickness. 
   
   
       8 . A container formed by using a pliable plastic film comprising a heat sealable sealing layer, the sealing layer being made of a mixture of a propylene-α-olefin random copolymer having a crystalline melting point T m  of 135 to 145° C. and a polypropylene homopolymer having a crystalline melting point T m  of higher than 160° C.,
 the container being provided with a sealed portion formed by heat sealing peripheral portions of the pliable plastic films in the state where the sealing layers thereof face with each other.   
   
   
       9 . The container according to  claim 8 , which is provided with an easily releasable sealed portion having a smaller peel strength than that of the sealed portion, and is also provided with a plurality of chambers partitioned with the sealed portion and the easily releasable sealed portion. 
   
   
       10 . The container according to  claim 9 , wherein the easily releasable sealed portion is heat sealed at a temperature which is higher than a crystalline melting point T m  of the propylene-α-olefin random copolymer having a crystalline melting point T m  of 135 to 145° C. and is lower than a crystalline melting point T m  of the polypropylene homopolymer having a crystalline melting point T m  of higher than 160° C. 
   
   
       11 . The container according to  claim 8 , which is subjected to a sterilization treatment at 121° C.