Biaxially Stretched Polyamide Film Molding Packaging Material
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Solution Overview
Problem
Existing packaging materials for lithium ion secondary batteries face challenges in moldability and productivity due to the need for a slipperiness imparting component and increased thickness of the outer layer film, which affects volume capacity and generates pinholes and cracks during molding.
Innovation Solution
A molding packaging material with a biaxially stretched polyamide film layer as the outer layer, a thermoplastic resin layer as the inner layer, and a metal foil layer in between, where the fracture strength to fracture strain ratio of the polyamide film is between 230 MPa to 360 MPa, and the static to dynamic friction ratios are within specific ranges, enhancing moldability without the need for a slipperiness coating and maintaining sufficient volume capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the surface of the outer layer film is coated with a fatty acid amide-based slipperiness imparting component, then the moldability is improved, but the productivity is reduced due to the additional coating process
Solution Approach 1:
The invention extracts and removes the slipperiness imparting component (fatty acid amide coating) from the packaging material structure. Instead of coating the outer layer film with slipperiness agents, the patent uses a biaxially stretched polyamide film with specifically controlled physical properties (fracture strength 200-400 MPa, fracture strain 0.3-0.8) that inherently provides the necessary moldability without requiring additional coating processes, thereby maintaining productivity.
2Manufacturing precision
If the thickness of the outer layer film is increased to be larger than the thickness of the metal foil layer, then the moldability is improved, but the volume capacity ratio of the content decreases
Solution Approach 1:
The invention changes the physical parameters of the outer layer film by using a biaxially stretched polyamide film with specifically controlled fracture strength (200-400 MPa) and fracture strain (0.3-0.8). This parameter optimization allows the film to achieve excellent moldability at thinner thicknesses, enabling the outer layer thickness to be equal to or less than the metal foil layer thickness while still preventing pinholes and cracks during molding, thus maintaining high volume capacity ratio.
3Ease of operation
If a slipperiness imparting component is used, then the slipping of the material into a die is improved, but the process complexity increases due to the coating process
Solution Approach 1:
The invention makes the outer layer film self-sufficient by selecting a biaxially stretched polyamide film with inherent properties (fracture strength 200-400 MPa, fracture strain 0.3-0.8) that automatically provide the necessary slipperiness and moldability. The material serves its own function without requiring external coating processes or additional slipperiness imparting components, thereby simplifying the overall process while maintaining ease of operation during molding.
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
This configuration suppresses stress concentration and uniform transformation during molding, preventing pinholes and cracks, ensuring excellent moldability and high-volume capacity without the need for a slipperiness coating, and maintaining sufficient volume capacity.
Implementation Method 1
This configuration suppresses stress concentration and uniform transformation during molding, preventing pinholes and cracks
Implementation Method 2
a biaxially stretched polyamide film layer as an outer layer
Implementation Method 3
when the coefficient of static friction between the outer surfaces of the biaxially stretched polyamide film layer is defined as 'A' and the coefficient of dynamic friction between the outer surfaces of the biaxially stretched polyamide film layer is defined as 'B', the A/B value is in the range of 1.0 to 2.0
Data Source
AI summary
A molding packaging material 1 of this invention contains a biaxially stretched polyamide film layer 2 as an outer layer, a thermoplastic resin layer 3 as an inner layer, and a metal foil layer 4 disposed between the both layers 2 and 3, in which a biaxially stretched polyamide film in which when the fracture strength of the film is defined as “X” and the fracture strain of the film is defined as “Y”, the X/Y value is 230 MPa to 360 MPa is used as the biaxially stretched polyamide film 2. The molding packaging material can secure excellent moldability even when the molding packaging material is not coated with a slipperiness imparting component.