Biaxially Stretched Polyamide Battery Case Material
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Solution Overview
Problem
Conventional battery case materials face productivity issues due to the need for lubrication coating and increased thickness, which affects formability and volume capacity ratio.
Innovation Solution
A battery case material comprising a biaxially stretched polyamide film layer, a thermoplastic resin unstretched film layer, and an aluminum foil layer, with the polyamide film having a specific density range and thickness, and integrated via a urethane adhesive layer, eliminating the need for lubrication coating and maintaining a suitable thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a fatty acid amide series lubrication giving component is coated onto the surface of the outer layer film to enhance sliding performance, then formability is improved, but productivity decreases due to added coating process and cleaning operations
Solution Approach 1:
The invention extracts and eliminates the lubrication giving component from the battery case material structure. Instead of coating lubrication substances onto the outer layer film, the patent uses a biaxially stretched polyamide film with specific physical properties (density 1.120-1.160 g/cm³, tensile strength ratio) that inherently provides the necessary sliding performance during deep drawing, thereby removing the coating process and associated cleaning operations
Solution Approach 2:
The invention changes the physical parameters of the outer layer film by specifying a biaxially stretched polyamide film with density of 1.120-1.160 g/cm³ and controlled tensile strength ratio (axial direction 70-130 MPa, transverse direction 60-120 MPa, ratio 0.85-1.15). These parameter changes enable the film to achieve excellent formability without requiring additional lubrication coatings
2Ease of manufacture
If the outer layer film is increased in thickness with respect to the thickness of the aluminum foil layer to improve formability, then formability is improved, but volume capacity ratio decreases
Solution Approach 1:
The invention changes the critical parameter of the outer layer film from thickness to density and molecular orientation characteristics. By specifying a biaxially stretched polyamide film with density of 1.120-1.160 g/cm³ and controlled tensile strength ratio, the patent achieves excellent formability with thinner films (0.01-0.05 mm), thereby maintaining high volume capacity ratio while improving formability
3Ease of operation
If a fatty acid amide series lubrication giving component is coated onto the outer layer film, then sliding performance is improved, but adherence to processing equipments occurs due to evaporation during vacuum deairing and sealing
Solution Approach 1:
The invention extracts and removes the lubrication giving component entirely from the battery case material system. The sliding performance is achieved through the inherent properties of the biaxially stretched polyamide film (density 1.120-1.160 g/cm³, specific tensile strength ratio) rather than through coated lubrication substances, thereby eliminating evaporation and adherence problems during vacuum processing
Solution Approach 2:
The invention replaces the lubrication giving component (which causes harmful evaporation and adherence) with a disposable-like functional property of the biaxially stretched polyamide film itself. The film's molecular orientation and physical structure provide the necessary sliding performance without requiring separate lubrication substances that would evaporate and cause adherence issues
Data Source
AI summary
A battery case material includes a biaxially stretched polyamide film layer as an outer layer, a thermoplastic resin unstretched film layer as an inner layer, and an aluminum foil layer interposed between the two film layers. As the biaxially stretched polyamide film, a biaxially stretched polyamide film having a density of 1,132 to 1,158 kg/m3 is used. In the battery case material, excellent formability can be secured without coating a lubrication giving component, and sufficient volume capacity ratio can be obtained.