Multi-layer film balancing optics and peel strength
Solution Overview
Problem
Protection films used for packaging and surface protection, such as those on electronic devices, often lack a balance of good optics, tear resistance, rigidity, and low stretching during peeling, which are essential for easy removal without damage or residue.
Innovation Solution
A multi-layer film comprising two outer layers of low density polyethylene and polypropylene, with a core layer of ethylene copolymer, specifically 1-octene, providing a balance of properties like good optics, tear resistance, and low stretching during peeling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single-layer protection film is used, then the structure is simple and manufacturing is easy, but it cannot achieve a balance of good optics, tear resistance, rigidity, and low stretching during peeling
Solution Approach 1:
The protection film is divided into multiple functional layers, each with specific polymer compositions and thicknesses. The multi-layer structure segments the film into an outer layer (providing release properties), a core layer (providing mechanical strength and optics), and an adhesive layer (providing bonding), allowing each layer to optimize its specific function while collectively achieving the desired balance of properties
Solution Approach 2:
The film uses composite materials with different polymer compositions in each layer. The outer layer uses a polymer blend optimized for release properties, the core layer uses high-density polymer for strength and optics, and the adhesive layer uses polymer designed for bonding. This composite structure allows the film to simultaneously achieve good optics, tear resistance, rigidity, and low stretching during peeling
2Strength
If the film has high tear resistance and rigidity, then protection capability is improved, but stretching during peeling increases making removal difficult
Solution Approach 1:
The film is segmented into layers with different mechanical properties. The core layer provides high tear resistance and rigidity for protection, while the outer layer is designed with specific polymer composition and thickness to provide release properties that reduce stretching during peeling. This segmentation allows the film to maintain strength while enabling easy removal
Solution Approach 2:
The outer layer uses a polymer blend with specific composition ratios and controlled thickness (5-50 μm) to optimize release properties. By adjusting the polymer composition parameters and layer thickness, the film achieves low stretching during peeling while the core layer maintains high tear resistance and rigidity
3Strength
If the outer layer thickness is increased to improve protection, then mechanical strength is improved, but optical clarity decreases
Solution Approach 1:
The film structure segments the thickness distribution across layers. The outer layer has controlled thickness (5-50 μm) optimized for release properties and optical clarity, while the core layer contains the majority of the film thickness providing mechanical strength. This segmentation allows the thinner outer layer to maintain optical clarity while the thicker core layer provides the necessary mechanical strength
Solution Approach 2:
The film uses composite material structure where the outer layer employs a polymer blend optimized for optical properties and release characteristics, while the core layer uses high-strength polymer. This composite approach allows the outer layer to remain thin for optical clarity while the core layer compensates for mechanical strength requirements
Data Source
AI summary
The present invention concerns a multi-layer film comprising at least three layers, with two outer layers and one core layer, wherein the two outer layers comprise between > 50 wt. % and 85 wt. % of a low density polyethylene having a density between 0.915 g/cm3 and 0.935 g/cm3 and between 15 wt.% and < 50 wt. % of a polypropylene with a density between 0.890 and 0.920 g//cm3 based on the total weight of polymers of the layer, wherein further the core layer comprises an ethylene copolymer comprising 1-octene and having a density between 0.910 g/cm3 and 0.925 g/cm3.