Biaxially Oriented HDPE Film for Recyclable Bag-Drop Packaging
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Solution Overview
Problem
Current large bags made from laminate polyester (PET) and polyethylene films pose recyclability issues due to the combination of dissimilar materials, necessitating the development of an all-polyethylene film that maintains good bag-drop performance.
Innovation Solution
A biaxially oriented polyethylene film comprising a core layer with specific weight percentages of olefin-block copolymer, low-density polyethylene, and high-density polyethylene, and tie layers with similar compositions, enhancing the film's structural integrity and recyclability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polyester (PET) is laminated to polyethylene films to create large bags, then good bag-drop performance is achieved, but recyclability problems occur due to dissimilar materials
Solution Approach 1:
The patent applies homogeneity by creating an all-polyethylene film structure where the core layer and tie layers are all composed of polyethylene materials (including recycled polyethylene). This eliminates the dissimilar material laminate (PET/PE) and creates a homogeneous polyethylene structure that maintains bag-drop performance while enabling recyclability, as the entire film can be processed and recycled as single-stream polyethylene.
Solution Approach 2:
The patent uses composite materials by combining different types of polyethylene (including recycled polyethylene, low-density polyethylene, and high-density polyethylene) in specific layers. The core layer comprises recycled polyethylene and polyethylene, while tie layers comprise low-density polyethylene and high-density polyethylene. This composite structure maintains mechanical properties and bag-drop performance while achieving recyclability through the use of recyclable polyethylene components.
2Ease of manufacture
If an all-polyethylene film is created to improve recyclability, then recyclability is enhanced, but structural integrity and bag-drop resistance may be compromised
Solution Approach 1:
The patent applies segmentation by dividing the film into distinct functional layers: a core layer providing bulk strength and drop resistance, and tie layers providing structural integrity and bonding. The core layer comprises recycled polyethylene and polyethylene, while tie layers comprise low-density polyethylene and high-density polyethylene. This segmented structure allows each layer to perform its specific function, maintaining overall strength and bag-drop resistance while enabling recyclability.
Solution Approach 2:
The patent applies parameter changes by carefully controlling the composition ratios and physical properties of different polyethylene components in each layer. The core layer uses specific ratios of recycled polyethylene to virgin polyethylene, while tie layers use specific combinations of low-density and high-density polyethylene. These parameter optimizations ensure that the film maintains adequate strength and bag-drop resistance properties while achieving recyclability through the use of recyclable polyethylene materials.
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 exhibits improved puncture resistance, dart-drop resistance, and bag-drop burst resistance, making it a more effective and recyclable alternative to traditional laminate films.
Implementation Method 1
biaxially oriented polyethylene film
Implementation Method 2
oriented in at least one direction, and/or oriented in both directions
Data Source
AI summary
In one example embodiment, disclosed is a polyethylene film, which in example embodiment(s) may comprise, consists essentially or, or consists of: (A) a core layer and a first tie layer on a first side of the core layer consisting essentially of: (i) at least about 20 wt. % olefin-block copolymer; (ii) at least about 40 wt. % low-density polyethylene; and (iii) at least about 40 wt. % high-density polyethylene, wherein “consisting essentially of” and “about,” among other words, are defined elsewhere in this disclosure; (B) a second tie layer on a second side of the core layer comprising, consisting essentially of, or consisting of: (i) at least about 20 wt. % low-density polyethylene; and (ii) at least about 40 wt. % high-density polyethylene; and (C) skin layer(s), be oriented in one or two directions; and contain additional layers external to the skin layer(s).