Battery Packaging Adhesive Composition for Wet-Heat Delamination
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Solution Overview
Problem
Existing electrical storage device packaging materials face issues with adhesive strength and durability in high temperature environments, leading to delamination and poor moldability due to hydrolysis of polyester skeletons and low molecular weight adhesives.
Innovation Solution
An adhesive formulation containing an ester bond-containing polyol, a polyisocyanate compound, and an epoxy resin, with specific molecular weight and concentration ranges, to enhance adhesive strength and durability in high temperature conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If a polyester polyurethane resin is used in the adhesive layer, then moldability and appearance are improved, but adhesive strength decreases due to hydrolysis of the polyester skeleton in high-temperature environments
Solution Approach 1:
The patent uses a composite adhesive system combining polyester polyol (for moldability and appearance) with polyisocyanate (for cross-linking and strength). This composite approach allows the adhesive to achieve both good moldability from the polyester component and high adhesive strength through cross-linking reactions with polyisocyanate, resolving the contradiction between shape formation and strength maintenance.
Solution Approach 2:
The patent specifies precise parameter ranges: polyol molecular weight of 10,000-50,000, polyisocyanate content of 5-50 parts by mass per 100 parts polyol, and isocyanate group content of 0.5-5.0 mmol/g. By optimizing these parameters, the adhesive achieves balanced performance with sufficient moldability from lower molecular weight polyol and adequate adhesive strength through controlled cross-linking density.
2Ease of manufacture
If the adhesive layer contains only polyester polyurethane resin without epoxy resin, then processability is improved, but delamination occurs in the molded product under severe external environment
Solution Approach 1:
The patent creates a composite adhesive system combining polyester polyol with polyisocyanate compound. This composite provides both processability from the polyester component and enhanced durability through cross-linking networks formed by polyisocyanate, preventing delamination under severe environmental conditions while maintaining ease of manufacturing.
Solution Approach 2:
The patent defines specific parameter ranges to balance processability and durability: polyol molecular weight of 10,000-50,000 for adequate flow and processing, polyisocyanate content of 5-50 parts by mass for sufficient cross-linking, and isocyanate group content of 0.5-5.0 mmol/g for controlled reaction rate. These parameter optimizations ensure both manufacturability and long-term reliability.
3Shape
If a polyol with low weight average molecular weight is used, then the adhesive is softer and more moldable, but adhesive strength becomes inferior in high temperature atmosphere
Solution Approach 1:
The patent optimizes the polyol molecular weight to 10,000-50,000, which provides adequate softness and moldability while maintaining sufficient adhesive strength through cross-linking. This parameter optimization ensures the adhesive remains processable at lower temperatures while developing adequate strength at elevated temperatures through the cross-linking network.
Solution Approach 2:
The patent combines polyester polyol with polyisocyanate compound to create a composite adhesive system. The polyester polyol provides moldability and flexibility, while the polyisocyanate forms cross-linking networks that maintain adhesive strength at high temperatures, resolving the contradiction between softness and high-temperature strength.
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 adhesive exhibits excellent stress relaxation, adhesive strength, and moldability in high temperature environments, providing improved wet heat durability and heat seal resistance.
Implementation Method 1
an adhesive for an electrical storage device packaging material containing a polyol compound (A), a polyisocyanate compound (B)...
Implementation Method 2
the molecular weight decreases due to hydrolysis of the polyester skeleton, and delamination occurs in the molded product when the packaging material is continuously exposed to a severe external environment
Data Source
AI summary
An adhesive for an electrical storage device packaging material containing a polyol compound (A), a polyisocyanate compound (B), and an epoxy resin (C), in which the polyol compound (A) contains an ester bond-containing polyol, and the following formula is satisfied when a stress at the time when a cured film obtained by performing curing under the condition of 80° C. for 2 weeks is stretched to twice its length at a speed of 6 mm/min under an environment of 20° C. and 65% RH is S1 [N/mm2], and a stress at the time when the cured film is held for 100 seconds in a stretched state is S2 [N/mm2]. Formula: 10.0≤(S1−S2)/S1×100≤40.0.