Thermally Conductive Polyurethane Adhesive for EV Battery Bonding
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Solution Overview
Problem
Current thermally conductive adhesives used in the automotive industry, particularly for electric vehicle battery compartments, fail to meet the requirements of high thermal conductivity, strong bond strength, and durability due to limitations in application process, cure speed, and exposure resistance.
Innovation Solution
A thermally-conductive, two-component polyurethane adhesive is developed, comprising a first component with polyisocyanate and a second component with polyetherpolyol, both containing thermally conductive fillers such as aluminium trihydroxide, expandable graphite, and graphene, which are mixed to achieve a concentration of 40 to 80 wt% thermally conductive filler in the adhesive.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If thermally conductive fillers are added to achieve high thermal conductivity, then thermal management performance is improved, but application process and cure speed deteriorate
Solution Approach 1:
The patent uses a composite filler system combining aluminium trihydroxide (ATH) with expandable graphite and graphene. This composite approach allows the fillers to work synergistically: ATH provides thermal conductivity and fire resistance, while graphite and graphene enhance thermal pathways. The two-component polyol system (polyester polyol and polyether polyol) creates a composite polymer matrix that balances cure speed and thermal properties, resolving the contradiction between thermal conductivity and cure speed.
Solution Approach 2:
The patent optimizes the particle size distribution of ATH filler using a multimodal distribution with specific D10, D50, and D90 values. This parameter optimization ensures proper filler packing and dispersion, maintaining thermal conductivity while preventing excessive viscosity that would slow application and curing. The aspect ratio of graphite and graphene is controlled at greater than 2 to enhance thermal pathways without overly impacting rheology.
2Temperature
If high concentration of thermally conductive filler is used to improve thermal conductivity, then thermal management is enhanced, but bond strength and durability worsen
Solution Approach 1:
The patent employs a composite filler system where aluminium trihydroxide is combined with expandable graphite and graphene in specific ratios. This composite approach creates a synergistic effect where the fillers form interconnected thermal pathways while the polyol matrix maintains structural integrity. The two-component polyol system (polyester and polyether) creates a balanced matrix that bonds effectively even with 40-80 wt% filler content.
Solution Approach 2:
The patent uses multimodal particle size distribution of ATH filler where different size ranges serve different functions: finer particles fill voids and create dense packing for thermal pathways, while coarser particles provide structural framework. This local differentiation of filler functions maintains bond strength while achieving high thermal conductivity through optimized filler architecture.
3Temperature
If thermally conductive fillers are added to meet thermal management requirements, then thermal conductivity is improved, but application process and exposure resistance worsen
Solution Approach 1:
The patent carefully controls the particle size parameters of ATH filler (D10, D50, D90 values) to optimize the balance between thermal conductivity and rheological properties. The aspect ratio of graphite and graphene is specified as greater than 2 to enhance thermal pathways while minimizing impact on application viscosity. These parameter optimizations enable the high-filler adhesive to maintain workable consistency for proper application.
Solution Approach 2:
The composite filler system of ATH, expandable graphite, and graphene creates a synergistic structure where the combination of materials improves thermal conductivity more efficiently than individual fillers alone, allowing lower overall filler concentrations that maintain better application properties. The two-component polyol system also contributes to balanced rheology for ease of application.
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, and reasonable elongation, effectively addressing the thermal management and structural integrity needs of electric vehicle battery compartments.
Implementation Method 1
Thermal conductivity is achieved predominantly using thermally conductive fillers... (a2, b3) thermally conductive filler which comprises: (i) aluminium trihydroxide having a multimodal particle size distribution; (ii) expandable graphite, and (iii) graphene, and/or graphite
Implementation Method 2
at least one catalyst capable of catalyzing the reaction of a hydroxyl group with an isocyanate group... (b2) at least one catalyst capable of catalyzing the reaction of a hydroxyl group with an isocyanate group
Implementation Method 3
A thermally-conductive, two-component polyurethane adhesive comprising: (A) a first component (isocyanate component), comprising: (a1) at least one polyisocyanate; (B) a second component (polyol component), comprising: (b1) at least one polyetherpolyol
Data Source
AI summary
Provided herein is a two-component polyurethane adhesive composition.