Polyolefin Packaging Film Structure for Recyclable Gas Barriers
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Solution Overview
Problem
Existing packaging films with non-polyolefin-based adhesives deteriorate the quality of recycled resins and do not adequately maintain gas barrier properties.
Innovation Solution
A packaging film structure comprising a polyolefin substrate layer, an anchor coat layer with a polyurethane resin, and a vapor deposition layer, bonded by a polyolefin adhesive resin, which mitigates expansion and contraction stresses to maintain gas barrier properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If non-polyolefin-based adhesives are used to bond the gas barrier layer, then gas barrier properties are maintained, but the quality of recycled resins deteriorates
Solution Approach 1:
The invention changes the chemical composition parameter of the adhesive layer from non-polyolefin-based resin to polyolefin-based resin (specifically polyethylene or polypropylene with 90 mass% or more content). This parameter change allows the adhesive to be compatible with polyolefin recycling processes while maintaining bonding functionality between the gas barrier layer and other film layers.
Solution Approach 2:
The invention creates a composite laminate structure consisting of multiple layers: polyolefin base layer, gas barrier layer (metal oxide or organic compound), and polyolefin-based adhesive layer. This composite structure integrates the gas barrier functionality with polyolefin compatibility, enabling both barrier performance and recyclability.
2Object-generated harmful factors
If polyolefin-based adhesive resin is used to increase the ratio of polyolefin-based resins, then recyclability improves, but gas barrier properties deteriorate
Solution Approach 1:
The invention segments the packaging film into distinct functional layers: a polyolefin base layer for recyclability, a dedicated gas barrier layer for barrier properties, and a polyolefin-based adhesive layer for bonding. This segmentation allows each layer to perform its specific function optimally without compromising the others.
Solution Approach 2:
The polyolefin-based adhesive layer acts as an intermediary between the polyolefin base layer and the gas barrier layer. It provides effective bonding while being chemically compatible with the polyolefin base layer, ensuring that the gas barrier layer remains intact and functional during recycling processes.
3Strength
If adhesive resin composition is bonded by melt extrusion, then bonding strength increases, but thermal expansion stresses affect the gas barrier layer
Solution Approach 1:
The invention changes the thermal parameters of the adhesive layer by using polyolefin-based resin with specific melting and thermal expansion characteristics. The adhesive layer's thermal properties are matched to the polyolefin base layer, reducing thermal expansion stress differentials during the melt extrusion bonding process and subsequent temperature variations.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The film suppresses the decrease in polyolefin-based resins and maintains excellent gas barrier properties, facilitating easy recycling and quality preservation of contents.
Implementation Method 1
a vapor deposition layer (40)
Implementation Method 2
heat of the adhesive resin composition transfers to the substrate layer via the vapor deposition layer
Implementation Method 3
is then cooled by a cooling roll to a low temperature
Data Source
AI summary
A packaging film includes a gas barrier film, an adhesive layer, and a sealant layer in this order. The gas barrier film includes a substrate layer, an anchor coat layer, and a vapor deposition layer in this order, the substrate layer includes a polyolefin substrate layer containing a polyolefin-based resin, the anchor coat layer contains a polyurethane resin, and the anchor coat layer has a thickness of 0.02 μm or more. The adhesive layer is obtained by bonding an adhesive resin composition containing a polyolefin adhesive resin to the gas barrier film by melt extrusion, and the sealant layer contains a polyolefin-based resin.