A high performance multilayer film for packaging

Abstract

A high-performance multilayer film for packaging, the structure being: BL/TIE/PO1/POX/PO3, obtained once by multilayer coextrusion and biaxial stretching, wherein: the total thickness of the multilayer film is 8 to 100 micrometers; the absolute value of the difference of the solubility parameters between the PO1 and PO3 layer materials is ≥0.1 and ≤0.5, and the absolute value of the difference of the cohesive energy density is ≥3, and ≤5; the solubility parameter and cohesive energy density of the POX bridge material are based on one of the PO1 and PO3 layer materials, and it's transitioned to the other in a gradient way; the absolute value of the difference of the solubility parameters between adjacent layers from the PO1 layer to the POX bridge and the PO3 layer is ≤0.1(J·cm−3)1/2, and the absolute value of the difference of the cohesive energy density is ≤3 J/cm3.

1 . A high-performance multilayer film for packaging, wherein: the structure of the multilayer film is as follows:
   BL/TIE/PO1/POX/PO3   Structure (1)
   In Structure (1), explicated from left to right:   BL represents the outer layer and the material is polyamide, or polyester or ethylene-vinyl alcohol copolymer;   TIE represents the bonding layer and the material is the maleic anhydride grafted copolymer with the PO1 layer material as the carrier;   PO1 represents a main stretching layer, also known as a PO1 layer, and the material is polyethylene or polypropylene;   POX represents a stretching transition bridge, also known as a POX bridge, and the material is any one or a mixture of at least two of polyethylene, polypropylene, modified polyethylene and modified polypropylene; X represents the number of layers, and X is 1, 2, 3, . . . , but not 0;   PO3 represents an inner layer, also known as a PO3 layer, and the material is any one or a mixture of at least two of polyethylene, polypropylene, modified polyethylene and modified polypropylene;   The multilayer film in structure (1) is obtained once by multilayer coextrusion and biaxial stretching, wherein, the biaxial stretching is carried out by a two-step stretching method of longitudinal stretching first and transverse stretching later;   The total thickness of the multilayer film is 8 micrometers to 100 micrometers, the thickness of the PO1 layer is 30 to 60% of the total thickness of the multilayer film; the thickness of the POX layer is 10 to 20% of the total thickness of the multilayer film; the thickness of the PO3 layer is 8 to 20% of the total thickness of the multilayer film;   The selection requirements for the density of materials of the PO1 layer, the POX layer and the PO3 layer are as follows: When the PO1 layer is polyethylene, the density of the PO1 layer is 0.87˜0.97 g/cm 3 ; when the PO1 layer is polypropylene, the density of the PO1 layer is 0.86˜0.91 g/cm 3 ; the density of the POX bridge is 0.86˜0.97 g/cm 3 , and the density of the PO3 layer is 0.87˜0.97 g/cm 3 ;   The absolute value of the difference of the solubility parameters between the PO1 layer and the PO3 layer material is greater than or equal to 0.1(J·cm −3 ) 1/2 , and less than or equal to 0.5(J·cm −3 ) 1/2 , and the absolute value of the difference of the cohesive energy density between the PO1 layer and the PO3 layer material is greater than or equal to 3 J/cm 3 , and less than or equal to 5 J/cm 3 ; the solubility parameter and the cohesive energy density of the POX bridge material are based on one of the PO1 layer material and the PO3 layer material, and it's transitioned to the other in a gradient way;   The absolute value of the difference of the solubility parameters between adjacent layers from the PO1 layer to the POX bridge and to the PO3 layer is less than or equal to 0.1(J·cm −3 ) 1/2 , and meanwhile, the absolute value of the difference of the cohesive energy density between adjacent layers from the PO1 layer to the POX bridge and to the PO3 layer is less than or equal to 3 J/cm 3 .   
     
     
         2 . The high-performance multilayer film for packaging of  claim 1 , wherein: the solubility parameter and the cohesive energy density of the POX bridge material are based on one of the PO1 layer material and the PO3 layer material, and it's transitioned to the other in an increment or decrement way; 
     
     
         3 . The high-performance multilayer film for packaging of  claim 1 , wherein: the solubility parameter and the cohesive energy density of the POX bridge material are based on one of the PO1 layer material and the PO3 layer material, and it's transitioned to the other in a V-shaped gradient way; 
     
     
         4 . The high-performance multilayer film for packaging of  claim 1 , wherein: the solubility parameter and the cohesive energy density of the POX bridge material are based on one of the PO1 layer material and the PO3 layer material, and it's transitioned to the other in a M-shaped gradient way; 
     
     
         5 . The high-performance multilayer film for packaging of  claim 1 , wherein: the solubility parameter and the cohesive energy density of the POX bridge material are based on one of the PO1 layer material and the PO3 layer material, and it's transitioned to the other in a W-shaped gradient way.