Battery Packaging Material Isocyanate Curing Control
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Solution Overview
Problem
Conventional battery packaging materials face challenges in achieving both electrolytic solution resistance and ink printing characteristics, particularly with the use of isocyanate group-containing curing agents, where insufficient reaction leads to poor electrolytic solution resistance and excessive reaction results in ink rejection, hindering printability, especially in pad printing.
Innovation Solution
A battery packaging material comprising a laminate structure with a protective layer, base material layer, and heat-sealable resin layer, where the absorbance ratios in specific infrared wavenumber ranges are optimized to ensure excellent electrolytic solution resistance and ink printing characteristics, using a urethane resin formed from polyols and isocyanate group-containing compounds, and incorporating an adhesive layer for improved layer adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a protective layer is formed by curing using an isocyanate group-containing curing agent, then electrolytic solution resistance is improved, but ink printing characteristics deteriorate when the reaction proceeds excessively
Solution Approach 1:
The patent applies parameter changes by precisely controlling the reaction degree of isocyanate groups through adjusting the curing conditions (temperature, time, catalyst amount) to achieve an unreacted isocyanate group content of 1-20 mmol/kg. This optimal parameter range ensures both sufficient electrolytic solution resistance and adequate ink adhesion, resolving the contradiction between over-curing (which improves resistance but harms printability) and under-curing (which maintains printability but insufficient resistance).
Solution Approach 2:
The patent implements feedback control by measuring the unreacted isocyanate group content and using this information to adjust and optimize the curing process. By monitoring the reaction progress and controlling the isocyanate group content within the specific range of 1-20 mmol/kg, the system achieves the optimal balance between electrolytic solution resistance and ink printing characteristics, preventing both insufficient and excessive reaction.
2Loss of information
If reverse printing is used to form a print on the base material layer, then discriminability is improved, but adhesion between layers deteriorates causing delamination
Solution Approach 1:
The patent applies the inversion principle by switching from reverse printing (printing on the base material layer) to direct printing (printing on the protective layer). This inverted approach allows the ink to be applied directly to the cured protective layer surface, maintaining both the discriminability function and the structural integrity of the laminate, thereby eliminating the delamination issue while preserving information display capability.
3Loss of information
If a seal with a print is attached to the base material layer, then discriminability is improved, but thickness and weight increase
Solution Approach 1:
The patent applies the merging principle by combining multiple functions into the protective layer: it serves as both the protective barrier against electrolytic solution and the printing substrate for information display. By integrating the printing function directly into the protective layer rather than adding a separate printed seal, the patent achieves discriminability while avoiding the increase in thickness and weight that would result from attaching an additional component.
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 optimized battery packaging material achieves superior electrolytic solution resistance and ink printing characteristics, allowing for effective ink fixation and print formation, even with pad printing, while maintaining structural integrity and reducing thickness and weight.
Implementation Method 1
a protective layer formed by curing using a curing agent such as an isocyanate group-containing curing agent
Implementation Method 2
a maximum value A of absorbance detected in an infrared wavenumber range of 2800 to 3000 cm−1 and a maximum value B of absorbance detected in an infrared wavenumber range of 2200 to 2300 cm−1
Data Source
AI summary
A battery packaging material that is excellent in electrolytic solution resistance and ink printing characteristics of the surface. A battery packaging material comprising a laminate having at least a protective layer, a base material layer, a barrier layer, and a heat-sealable resin layer in this order, wherein a maximum value A of absorbance detected in an infrared wavenumber range of 2800 to 3000 cm−1 and a maximum value B of absorbance detected in an infrared wavenumber range of 2200 to 2300 cm−1 satisfy the relation: 0.05≤B/A≤0.75, as measured from an outermost surface of the protective layer, using attenuated total reflection Fourier transform infrared spectroscopy.