Battery Case Adhesive Composition for Low-Temperature Lamination

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Solution Overview

Problem

Existing adhesives used in packaging materials for lithium batteries face challenges in achieving both low-temperature lamination process adhesion and heat resistance, which are crucial for improving productivity and durability.

Innovation Solution

An adhesive composition comprising a crystalline modified olefin polymer, an acid anhydride monomer with a ring structure and multiple acid anhydride groups, and a cross-linking agent, such as an epoxy compound, is used to enhance adhesion and heat resistance through a cross-linking reaction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If an adhesive composition containing maleic anhydride-modified propylene-butene copolymer, epoxy resin, and 1,2,3,6-tetrahydrophthalic anhydride is used, then heat resistance is improved, but adhesion during low-temperature lamination process deteriorates

Engineering Contradiction:
Improveheat resistanceVSAvoidadhesion during low-temperature lamination
Core Design Contradiction:
TemperatureVSUse of energy by moving object

Solution Approach 1:

The invention changes the chemical parameters of the adhesive composition by specifying precise component ratios: maleic anhydride-modified propylene-butene copolymer (5-20 mass%), epoxy resin (70-85 mass%), and 1,2,3,6-tetrahydrophthalic anhydride (5-20 mass%). This parameter optimization enables the adhesive to achieve both low-temperature lamination adhesion and heat resistance by balancing the reactive components for cross-linking with the base polymer for initial bonding

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention uses a composite adhesive system combining three distinct components: maleic anhydride-modified propylene-butene copolymer (provides low-temperature adhesion), epoxy resin (provides cross-linking and heat resistance), and 1,2,3,6-tetrahydrophthalic anhydride (provides additional cross-linking and thermal stability). The synergistic interaction of these composite materials resolves the contradiction between low-temperature bonding and high-temperature performance

Inventive Principle:
Principle #40Composite materials

2Productivity

If a low-temperature lamination process is implemented to improve productivity, then manufacturing efficiency is improved, but adhesion performance deteriorates

Engineering Contradiction:
Improvelamination process efficiencyVSAvoidadhesion strength
Core Design Contradiction:
ProductivityVSStrength

Solution Approach 1:

The invention optimizes the adhesive composition parameters to enable effective bonding at lower temperatures. The maleic anhydride-modified propylene-butene copolymer (5-20 mass%) provides excellent low-temperature adhesion, while the controlled ratio of epoxy resin and anhydride ensures sufficient cross-linking even at reduced lamination temperatures, thus maintaining adhesion strength while improving productivity

Inventive Principle:
Principle #35Parameter changes

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 composition achieves excellent adhesion during low-temperature lamination and improved heat resistance, making it suitable for packaging materials, particularly for battery cases.

Implementation Method 1

Such an adhesive composition is cured by a cross-linking reaction between the crystalline modified olefin polymer, the acid anhydride monomer, and the cross-linking agent

Methodology Applied
Scientific EffectCross-linking reaction: Chemical Bonding

Implementation Method 2

The acid anhydride monomer has two or more acid anhydride groups. Therefore, in the cross-linking reaction, the cross-link density is improved

Methodology Applied
Scientific EffectCross-linking reaction: Chemical Bonding

Data Source

PatentEP4585660A1Adhesive composition, laminate, packaging material, and packaging material for battery cases
Publication Date: 2025.07.16 MITSUI CHEMICALS INC
  • EP4585660A1 patent drawingFigure 1~2B
  • EP4585660A1 patent drawingFigure 3~4
  • EP4585660A1 patent drawing

AI summary

An adhesive composition includes a crystalline modified olefin polymer, an acid anhydride monomer, and a cross-linking agent. The crystalline modified olefin polymer is obtained by modifying a crystalline α-olefin polymer having 2 to 20 carbon atoms with a monomer having a functional group capable of reacting with an epoxy group or an oxazoline group. The acid anhydride monomer has a ring structure and two or more acid anhydride groups. The cross-linking agent includes an epoxy compound and/or an oxazoline compound.