Battery Pouch Film Primer Composition for Peel Strength and Formability
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Solution Overview
Problem
Existing secondary battery pouch films face challenges in achieving optimal formability, initial peel strength, hydrofluoric acid resistance, and electrolyte resistance, particularly in medium-sized and large-sized applications.
Innovation Solution
A primer layer composition based on an organic solvent-based emulsion is used, containing acid-modified polypropylene and a curing agent, with a curing start temperature of 150° C. or lower and a drying process temperature of 150° C. or lower, eliminating the need for thermal lamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a conventional primer layer composition is used, then initial peel strength is achieved, but formability deteriorates
Solution Approach 1:
The patent changes the chemical composition parameters of the primer layer by introducing acid-modified polypropylene with specific carboxyl group content (0.1-5.0 mmol/g) and combining it with specific curing agents. This parameter optimization enables the primer to achieve both adequate initial peel strength and excellent formability, resolving the contradiction between strength and manufacturability.
Solution Approach 2:
The patent creates a composite primer layer system by combining acid-modified polypropylene with specific curing agents (polyamide, polyisocyanate, or carboxylic acid). This composite approach allows the primer to exhibit both adhesive properties for initial peel strength and flexibility for formability, achieving 6.5 mm or greater formability while maintaining peel strength of 14.0 N/mm or higher.
2Strength
If curing temperature is increased to improve initial peel strength, then adhesive strength improves, but hydrofluoric acid resistance deteriorates
Solution Approach 1:
The patent optimizes the curing temperature parameter to 150°C or lower, which is lower than conventional curing temperatures. This parameter change, combined with the specific primer composition (acid-modified polypropylene with controlled carboxyl content and specific curing agents), achieves both high initial peel strength (14.0 N/mm or higher) and excellent hydrofluoric acid resistance (5.0 N/mm or higher), resolving the contradiction between strength and chemical resistance.
3Strength
If thermal lamination process is used to improve sealant layer adhesion, then adhesive strength improves, but formability deteriorates
Solution Approach 1:
The patent extracts and eliminates the thermal lamination process from the manufacturing sequence. By designing a primer layer composition that achieves adequate adhesion without requiring high-temperature thermal lamination, the patent maintains formability of 6.5 mm or greater while still achieving initial peel strength of 14.0 N/mm or higher, resolving the contradiction between adhesion and formability.
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 solution achieves excellent formability of 6.5 mm or larger, initial peel strength of 14.0 N/mm or higher, hydrofluoric acid resistance of 5.0 N/mm or higher, and electrolyte resistance equal to or higher than 90% of the initial peel strength.
Implementation Method 1
a drying process of applying a primer layer composition on the metal layer and heating to dry the primer layer composition and cure at least a part of the primer layer composition
Implementation Method 2
heating to dry the primer layer composition and cure at least a part of the primer layer composition
Data Source
AI summary
Disclosed are a method for manufacturing a secondary battery pouch film having at least an outer layer, a metal layer, a primer layer, and a sealant layer, or at least an outer layer, a metal layer, a primer layer, a melt-extrusion resin layer, and a sealant layer in this order, the method including: a drying process of applying and heating a primer layer composition on the metal layer so as to dry the primer layer composition and cure at least a part of the primer layer composition. The organic solvent-based emulsion composition contains acid-modified polypropylene and a curing agent and has a curing start temperature of 150° C. or lower, preferably 135° C. to 150° C., and a drying process temperature of 150° C. or lower, preferably 135° C. to 150° C. The method is not subjected to a thermal lamination process when laminating sealant layer.