Polybutylene Terephthalate Battery Packaging Laminate
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Solution Overview
Problem
Conventional film-shaped battery packaging materials face challenges in moldability and warp resistance, particularly when using polybutylene terephthalate films, as they require complex apparatuses and result in low productivity, and are prone to pinholes and cracks during molding, which can lead to short-circuits.
Innovation Solution
A battery packaging material comprising a laminate structure with a base material layer, a barrier layer, and a cured resin layer, where at least one base material layer is formed of a polybutylene terephthalate film with a piercing strength-to-thickness ratio of 1.02 N/µm or more, enhancing moldability and reducing warp likelihood.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If polybutylene terephthalate film is used as base material layer, then dimensional stability and chemical resistance are improved, but moldability deteriorates due to pinholes and cracks during molding
Solution Approach 1:
The invention uses a laminate structure combining polybutylene terephthalate film (providing dimensional stability and chemical resistance) with polyethylene terephthalate film (providing good moldability and pinhole resistance). This composite structure allows both materials to contribute their respective advantages, resolving the contradiction between stability and moldability.
Solution Approach 2:
Different layers of the laminate serve different functions: the polybutylene terephthalate layer provides dimensional stability and chemical resistance where needed, while the polyethylene terephthalate layer provides moldability and pinhole resistance during the molding process. Each material is positioned where its specific properties are most beneficial.
2Weight of moving object
If film thickness is reduced to achieve weight reduction, then weight is improved, but reliability deteriorates due to increased likelihood of pinholes and cracks
Solution Approach 1:
The laminate structure combines thin films of polybutylene terephthalate and polyethylene terephthalate to achieve weight reduction while maintaining reliability. The polyethylene terephthalate layer specifically provides pinhole and crack resistance even at reduced thickness, allowing the overall package to be lighter without sacrificing reliability.
3Temperature
If polybutylene terephthalate film is used to improve crystallinity and thermal stability, then thermal stability is improved, but ease of manufacture deteriorates due to complex lamination apparatus requirements
Solution Approach 1:
The invention uses a practical laminate structure of two films that can be manufactured using conventional lamination equipment. This approach achieves thermal stability through the polybutylene terephthalate layer without requiring complex apparatus, as the two-film laminate is compatible with standard manufacturing processes.
4Stability of the object's composition
If aluminum alloy foil layer is used for barrier properties, then chemical resistance is improved, but weight is worsened due to metal density
Solution Approach 1:
The invention replaces the traditional aluminum alloy foil (heavy but provides barrier) with a laminate of plastic films that includes polyethylene terephthalate and polybutylene terephthalate. This plastic-based laminate provides comparable chemical resistance and barrier properties while significantly reducing weight, accepting that the plastic films are consumable packaging materials rather than reusable metal components.
Data Source
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AI summary
Provided is a packaging material for batteries, which is not susceptible to warping, while having excellent formability. A packaging material for batteries according to the present invention is configured from a laminate that is sequentially provided at least with one or more substrate layers, a barrier layer, a cured resin layer and a thermally fusible resin layer in this order. At least one of the substrate layers is formed of a polybutylene terephthalate film; and the value (X/Y) which is obtained by dividing the puncture strength X (N) of the laminate by the thickness Y (µm) of the polybutylene terephthalate film, said puncture strength X (N) being determined by piercing the laminate from the substrate layer side by a method that complies with the prescription of JIS Z1707 (1997), is 1.02 N/µm or more.