Thermally Conductive Polyurethane Adhesive With Balanced Bond Strength
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Solution Overview
Problem
Existing thermally-conductive adhesives for battery applications struggle to achieve a balance of high thermal conductivity, elongation at break, flame-resistance, low abrasiveness, and good adhesion to various materials while maintaining cost-effectiveness.
Innovation Solution
A two-component, thermally-conductive polyurethane adhesive comprising NCO-terminated and OH-terminated prepolymers, with fillers such as aluminium trihydroxide and graphite, to achieve enhanced thermal conductivity, mechanical stability, and adhesion properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If high thermal conductivity is achieved through filler addition, then thermal management performance improves, but adhesion and mechanical properties deteriorate
Solution Approach 1:
The patent modifies the chemical composition parameters of the adhesive system by introducing a tri-functional polyol component with specific molecular weight range (500-2000 g/mol) and functionality (3) that reacts with isocyanate to form crosslinked structures. This chemical parameter change enables the adhesive to maintain strong bonding and mechanical properties while accommodating high filler loads (40-80 wt% total inorganic fillers) for thermal conductivity without sacrificing adhesion to battery components.
2Temperature
If high filler content is used to improve thermal conductivity, then thermal management efficiency improves, but viscosity and processing difficulty increase
Solution Approach 1:
The patent adjusts the polyol component parameters including molecular weight (500-2000 g/mol), functionality (3), and hydroxyl value (20-80 mg KOH/g) to optimize the balance between filler loading capacity and processing viscosity. The specific tri-functional polyol structure provides sufficient reactivity and crosslinking density to maintain low viscosity even with 40-80 wt% inorganic fillers, enabling easy dispensing and processing while achieving high thermal conductivity.
3Reliability
If elongation at break is increased to accommodate thermal expansion differences, then bonding reliability improves, but structural strength may decrease
Solution Approach 1:
The patent utilizes the tri-functional polyol's crosslinking reaction with isocyanate to create a balanced polymer network structure that simultaneously provides both elasticity and strength. The specific molecular weight and functionality of the polyol component enable the cured adhesive to achieve elongation at break greater than 25% for accommodating thermal expansion differences between battery components, while maintaining structural strength through the crosslinked network formed by the tri-functional crosslinking mechanism.
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 achieves good thermal conductivity, high bond strength, flame-retardancy, low abrasiveness, and reasonable elongation, effectively addressing the challenges faced by existing adhesives.
Implementation Method 1
The cells or modules are connected to the cooling plate through a thermally-conductive material. In order to increase the mechanical stability of the battery a thermally conductive adhesive is needed.
Implementation Method 2
a catalyst capable of catalyzing the reaction of isocyanate groups with OH groups
Implementation Method 3
A. a first component (isocyanate) comprising an NCO-terminated prepolymer made by reacting at least one polyol with at least one polyisocyanate; B. a second component (polyol) comprising an OH-terminated prepolymer made by reacting at least one polyol with at least one polyisocyanate
Data Source
AI summary
Provided herein is a two-component polyurethane adhesive composition.