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.Math.cm.sup.−3).sup.1/2, and the absolute value of the difference of the cohesive energy density is ≤3 J/cm.sup.3).

Claims

1. A high-performance multilayer film for packaging, wherein the high-performance multilayer has a structure according to Structure (1):
BL/TIE/PO1/POX/PO3  Structure (1) wherein in Structure (1) BL represents an outer layer and is comprised of a polyamide, a polyester or an ethylene-vinyl alcohol copolymer material; TIE represents a bonding layer and is comprised of a maleic anhydride grafted copolymer material; PO1 represents a main stretching layer and is comprised of polyethylene or polypropylene material; POX represents a stretching transition bridge and is comprised of any one or a mixture of at least two of polyethylene, polypropylene, modified polyethylene and modified polypropylene material, wherein the POX bridge is comprised of one or more layers; and PO3 represents an inner layer and is comprised of any one or a mixture of at least two of polyethylene, polypropylene, modified polyethylene and modified polypropylene material; wherein the multilayer film is obtained 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, thereby obtaining the multilayer film in coextruded and biaxially stretched form; wherein a total thickness of the multilayer film is from 8 micrometers to 100 micrometers, a thickness of the PO1 layer comprises from 30 to 60% of the total thickness of the multilayer film; a thickness of the POX bridge comprises from 10 to 20% of the total thickness of the multilayer film; and a thickness of the PO3 layer comprises from 8 to 20% of the total thickness of the multilayer film; wherein when the PO1 layer material is polyethylene, a density of the PO1 layer is from about 0.87 to about 0.97 g/cm.sup.3, or when the PO1 layer material is polypropylene, the density of the PO1 layer is from about 0.86 to about 0.91 g/cm.sup.3, a density of the POX bridge is from about 0.86 to about 0.97 g/cm.sup.3, and a density of the PO3 layer is from about 0.87 to about 0.97 g/cm.sup.3; wherein an absolute value of a difference of solubility parameters between the PO1 layer material and the PO3 layer material is greater than or equal to 0.1 (J.Math.cm.sup.−3).sup.1/2 and less than or equal to 0.5 (j.Math.cm.sup.−3).sup.1/2, and an absolute value of a difference of cohesive energy density between the PO1 layer material and the PO3 layer material is greater than or equal to 3 J/cm.sup.3 and less than or equal to 5 J/cm.sup.3; a solubility parameter and a cohesive energy density of the POX bridge material are based on the solubility parameter and the cohesive energy density, respectively, of one of the PO1 layer material and the PO3 layer material, and the solubility parameter and the cohesive energy density of the POX bridge material are values that form a gradient to transition from the solubility parameter and the cohesive energy density, respectively, of the one of the PO1 layer material and the PO3 layer material toward the solubility parameter and the cohesive energy density, respectively, of the other one of the PO1 layer material and the PO3 layer material; and wherein an absolute value of the difference of the solubility parameters between the PO1 layer material and the POX bridge material and between the PO3 layer material and the POX bridge material, is less than or equal to 0.1 (J.Math.cm.sup.−3).sup.1/2, and an absolute value of the difference of the cohesive energy density between the PO1 layer material and the POX bridge material and between the PO3 layer material and the POX bridge material is less than or equal to 3 J/cm.sup.3.

2. The high-performance multilayer film for packaging of claim 1, wherein the gradient of the solubility parameter and the cohesive energy density of the POX bridge material is either incremental or decremental.

3. The high-performance multilayer film for packaging of claim 1, wherein the gradient of the solubility parameter and the cohesive energy density of the POX bridge material is a V-shaped gradient.

4. The high-performance multilayer film for packaging of claim 1, wherein the gradient of the solubility parameter and the cohesive energy density of the POX bridge material is a M-shaped gradient.

5. The high-performance multilayer film for packaging of claim 1, wherein the gradient of the solubility parameter and the cohesive energy density of the POX bridge material is a W-shaped gradient.

Description

SPECIFIC EMBODIMENT

[0026] With reference to the embodiments, the present invention will be described in detail: Embodiment 1: In the structure of multilayer film, PO1 is polypropylene; POX is high density polyethylene/linear low density polyethylene+high density polyethylene/linear low density polyethylene+ethylene-octene copolymer; ethylene-octene copolymer, the number of layers is four; PO3 is polypropylene. See Table 1:

TABLE-US-00001 TABLE 1 Absolute value of the difference of the cohesive Absolute value of energy the difference of density the solubility Cohesive between Solubility parameters between energy adjacent Density parameter adjacent layers density layers Layer Polymer (g/cm.sup.3) (J .Math. cm.sup.−3).sup.1/2 (J .Math. cm.sup.−3).sup.1/2 (J/cm.sup.3) (J/cm.sup.3) PO1 Polypropylene 0.9000 8.10 0.10 65.61 1.61 (homopolymerization) PP POX High density 0.9600 8.00 64.00 polyethylene HDPE Linear low density 0.9250 7.94 0.06 63.04 0.96 polyethylene LLDPE + high density polyethylene Linear low density 0.9460 7.98 0.04 63.68 0.64 polyethylene LLDPE + ethylene-octene copolymer Ethylene-octene 0.9190 7.89 0.09 62.25 1.43 copolymer PO3 Polypropylene 0.9050 7.80 0.09 60.84 1.41 (copolymerization) PP
The density, solubility parameter and cohesive energy density of each polymer can be seen in Table 1, and the absolute value of the difference of the solubility parameters between the PO1 layer and the PO3 layer material is 0.30 (J.Math.cm.sup.−3).sup.1/2. 0.1 (J.Math.cm.sup.−3).sup.1/2<0.30 (J.Math.cm.sup.−3).sup.1/2<0.5 (J.Math.cm.sup.−3).sup.1/2, and the absolute value of the difference of the cohesive energy density between the PO1 layer and the PO3 layer material is 4.773 J/cm.sup.3. 3 J/cm.sup.3<4.773 J/cm.sup.3<5 J/cm.sup.3, which meets the conditions for setting the stretching transition bridge. The stretching transition bridge POX is a four-layer structure, and the solubility parameter and the cohesive energy density of the POX bridge material are based on the PO1 layer material, and it's transitioned to the PO3 layer material in a V-shaped 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.Math.cm.sup.−3).sup.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.sup.3.

[0027] The following embodiments are presented in a table, and no more detailed description is made by text to save space.

Embodiment 2

[0028] In the structure of multilayer film, PO1 is polypropylene; POX is high density, polyethylene/linear low density polyethylene/high density polyethylene, the number of layers is three; PO3 is ethylene-octene copolymer. See Table 2:

TABLE-US-00002 TABLE 2 Absolute value of the difference of the cohesive Absolute value of energy the difference of density the solubility Cohesive between Solubility parameters between energy adjacent Density parameter adjacent layers density layers Layer Polymer (g/cm.sup.3) (J .Math. cm.sup.−3).sup.1/2 (J .Math. cm.sup.−3).sup.1/2 (J/cm.sup.3) (J/cm.sup.3) PO1 Polypropylene 0.9000 8.10 0.10 65.61 1.61 (homopolymerization) High density 0.9600 8.00 64.00 polyethylene HDPE POX Linear low density 0.9250 7.95 0.05 63.20 0.80 polyethylene LLDPE High density 0.9200 7.90 0.05 62.41 0.79 polyethylene HDPE PO3 Ethylene-octene 0.9100 7.80 0.10 60.80 1.61 copolymer
The solubility parameter and the cohesive energy density of the POX bridge material are based on the PO1 layer material, and it's transitioned to the PO3 layer material.

Embodiment 3

[0029] In the structure of multilayer film, PO1 is high density polyethylene; POX is linear low density polyethylene/low density polyethylene, the number of layers is two; PO3 is ethylene-octene copolymer. See Table 3:

TABLE-US-00003 TABLE 3 Absolute value of the difference of the cohesive Absolute value of energy the difference of density the solubility Cohesive between Solubility parameters between energy adjacent Density parameter adjacent layers density layers Layer Polymer (g/cm.sup.3) (J .Math. cm.sup.−3).sup.1/2 (J .Math. cm.sup.−3).sup.1/2 (J/cm.sup.3) (J/cm.sup.3) PO1 High density 0.9600 8.00 0.05 64.00 0.80 polyethylene HDPE POX Linear low 0.9250 7.95 0.05 63.20 0.79 density polyethylene LLDPE Low density 0.9200 7.90 62.41 polyethylene LDPE PO3 Ethylene-octene 0.9100 7.80 0.10 60.80 1.61 copolymer
The solubility parameter and the cohesive energy density of the POX bridge material are based on the PO1 layer material, and it's transitioned to the PO3 layer material.

Embodiment 4

[0030] In the structure of multilayer film, PO1 is high density polyethylene; POX is linear low density polyethylene/high density polyethylene+low density polyethylene, the number of layers is two; PO3 is high density polyethylene+polypropylene. See Table 4:

TABLE-US-00004 TABLE 4 Absolute value of the difference of the cohesive Absolute value of energy the difference of density the solubility Cohesive between Solubility parameters between energy adjacent Density parameter adjacent layers density layers Layer Polymer (g/cm.sup.3) (J .Math. cm.sup.−3).sup.1/2 (J .Math. cm.sup.−3).sup.1/2 (J/cm.sup.3) (J/cm.sup.3) PO1 High density 0.9600 8.00 0.05 64.00 0.80 polyethylene HDPE Linear low 0.9250 7.95 0.05 63.20 0.79 density polyethylene LLDPE POX High density 0.9200 7.90 62.41 polyethylene LDPE + low density polyethylene LDPE PO3 High density 0.9188 7.85 0.05 61.62 0.79 polyethylene HDPE + polypropylene PP
The solubility parameter and the cohesive energy density of the POX bridge material are based on the PO1 layer material, and ifs transitioned to the PO3 layer material.

Embodiment 5

[0031] In the structure of multilayer film, PO1 is polypropylene; POX is high density polyethylene/linear low density polyethylene/low density polyethylene, the number of layers is three; PO3 is ethylene-octene copolymer. See Table 5:

TABLE-US-00005 TABLE 5 Absolute value of the difference of the cohesive Absolute value of energy the difference of density the solubility Cohesive between Solubility parameters between energy adjacent Density parameter adjacent layers density layers Layer Polymer (g/cm.sup.3) (J .Math. cm.sup.−3).sup.1/2 (J .Math. cm.sup.−3).sup.1/2 (J/cm.sup.3) (J/cm.sup.3) PO1 Polypropylene 0.9000 8.10 0.10 65.01 1.61 (homopolymerization) High density 0.9600 8.00 0.05 64.00 0.80 polyethylene HDPE POX Linear low density 0.9250 7.95 63.20 polyethylene LLDPE Low density 0.9200 7.90 0.05 62.41 0.79 polyethylene LDPE PO3 Ethyiene-octene 0.9100 7.80 0.10 60.80 1.61 copolymer
The solubility parameter and the cohesive energy density of the POX bridge material are based on the PO1 layer material, and it's transitioned to the PO3 layer material.

Embodiment 6

[0032] In the structure of multilayer film, PO1 is polypropylene; POX is high density polyethylene/linear low density polyethylene+ethylene-octene copolymer, the number of layers is two; PO3 is ethylene-octene copolymer. See Table 6:

TABLE-US-00006 TABLE 6 Absolute value of the difference of the cohesive Absolute value of energy the difference of density the solubility Cohesive between Solubility parameters between energy adjacent Density parameter adjacent layers density layers Layer Polymer (g/cm.sup.3) (J .Math. cm.sup.−3).sup.1/2 (J .Math. cm.sup.−3).sup.1/2 (J/cm.sup.3) (J/cm.sup.3) PO1 Polypropylene 0.9 8.1 0.1 65.61 1.61 (homopolymerization) PP POX High density 0.96 8 64 0.96 polyethylene HDPE Linear low density 0.9198 7.9 0.1 63.04 polyethylene LLDPE + ethylene-octene copolymer PO3 Ethylene-octene 0.91 7.8 0.1 60.84 2.2 copolymer PP
The solubility parameter and the cohesive energy density of the POX bridge material are based on the PO1 layer material, and it's transitioned to the PO3 layer material.

Embodiment 7

[0033] In the structure of multilayer film, PO1 is polypropylene; POX is high density polyethylene+ethylene-octene copolymer ethylene-octene copolymer linear low density polyethylene+ethylene-octene copolymer, the number of layers is three; PO3 is polypropylene. See Table 7:

TABLE-US-00007 TABLE 7 Absolute value of the difference of the cohesive Absolute value of energy the difference of density the solubility Cohesive between Solubility parameters between energy adjacent Density parameter adjacent layers density layers Layer Polymer (g/cm.sup.3) (J .Math. cm.sup.−3).sup.1/2 (J .Math. cm.sup.−3).sup.1/2 (J/cm.sup.3) (J/cm.sup.3) PO1 Polypropylene 0.9000 7.8 0.05 60.84 0.78 (homopolymerization) PP POX High density 0.9500 7.85 0.05 61.62 0.78 polyethylene HDPE + ethylene-octene copolymer Ethylene-octene 0.9100 7.8 60.84 copolymer Linear low density 0.9190 7.9 0.1 62.41 1.57 polyethylene LLDPE + ethylene-octene copolymer PO3 Polypropylene 0.9088 7.995 0.095 63.92 1.51 (copolymerization) PP + modified polyethylene (EVA)
The solubility parameter and the cohesive energy density of the POX bridge material are based on the PO1 layer material, and it's transitioned to the PO3 layer material in a V-shaped way,

Embodiment 8

[0034] In the structure of multilayer film, PO1 is polypropylene; POX is modified polyethylene+high density polyethylene/linear low density polyethylene/linear low density polyethylene+modified polyethylene, the number of layers is three; PO3 is ethylene-octene copolymer. See Table 8:

TABLE-US-00008 TABLE 8 Absolute value of the difference of the cohesive Absolute value of energy the difference of density the solubility Cohesive between Solubility parameters between energy adjacent Density parameter adjacent layers density layers Layer Polymer (g/cm.sup.3) (J .Math. cm.sup.−3).sup.1/2 (J .Math. cm.sup.−3).sup.1/2 (J/cm.sup.3) (J/cm.sup.3) PO1 Polypropylene 0.9000 8.10 0.05 65.61 0.81 (homopolymerization) PP POX Modified 0.9585 8.05 0.10 64.80 1.60 polyethylene (EVA) + high density polyethylene HDPE Linear low density 0.9250 7.95 62.20 polyethylene LLDPE Linear low density 0.9500 7.85 0.10 61.62 1.58 polyethylene LLDPE + Modified polyethylene (EVA) PO3 Polypropylene 0.9100 7.80 0.05 60.84 0.78 (copolymerization) PP + modified polyethylene (EVA)
The solubility parameter and the cohesive energy density of the POX bridge material are based on the PO1 layer material, and it's transitioned to the PO3 layer material.

[0035] It should be noted that the above described embodiments are only for illustration of technical concept and characteristics of present invention with purpose of making those skilled in the art understand the present invention. The technicians in this art could make change on the basis of the above embodiment, such as choosing different densities of materials, choosing different activators, etc, and thus these embodiments shall not limit the protection range of present invention. The equivalent changes or modifications according to spiritual essence of present invention shall fall in the protection scope of present invention.