Polyurethane Thermal Interface Material for Battery Vehicles
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Solution Overview
Problem
Current thermal interface materials (TIM) for battery-powered vehicles face challenges in achieving high thermal conductivity, cost-effectiveness, ease of application, and weather resistance, particularly with high loadings of aluminum trihydroxide (ATH) which tend to fail aging tests due to cracking under climate change conditions.
Innovation Solution
A thermal interface material composition comprising a urethane-based binder component with non-reactive polyurethane prepolymers and high loadings of aluminum trihydroxide (80-95 wt%), where the polyurethane prepolymers are reaction products of polyisocyanates and aliphatic monols, substantially free of residual isocyanate groups, and optionally include other polyurethanes and additives for improved properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If high loading of aluminum trihydroxide (80 wt% or higher) is used to achieve high thermal conductivity, then thermal conductivity increases, but the material fails aging tests due to cracking under climate change conditions
Solution Approach 1:
The patent changes the chemical composition parameters of the binder system by using a specific ratio of polyol (5-30 wt%) combined with reactive (5-40 wt%) and non-reactive (5-40 wt%) polyurethane prepolymers. This parameter optimization allows the binder to maintain flexibility and adhesion at high ATH loadings (80-95 wt%) while resisting climate-induced cracking, thus resolving the contradiction between thermal conductivity and weather resistance
Solution Approach 2:
The patent creates a composite binder system combining three different polymeric components (polyol, reactive polyurethane prepolymer, and non-reactive polyurethane prepolymer) with specific molecular weight ranges and functional groups. This multi-component composite approach provides synergistic effects where each component contributes specific properties: polyol provides flexibility, reactive prepolymer provides crosslinking and strength, and non-reactive prepolymer provides processability and crack resistance, enabling the TIM to withstand both high thermal conductivity requirements and climate change conditions
2Ease of operation
If liquid based polymeric binders are used for ease of application, then ease of application improves, but the material tends to fail aging tests with crack formation
Solution Approach 1:
The patent optimizes the molecular weight parameters of the polyurethane prepolymers (2,000-50,000 g/mol for non-reactive, 1,000-30,000 g/mol for reactive) and controls the NCO content (0.1-10.0 wt%) to achieve the right balance between liquid-state processability and final cured network strength. This parameter control allows easy application in liquid form while ensuring weather resistance after curing
Solution Approach 2:
The patent incorporates reactive polyurethane prepolymer with isocyanate groups that will crosslink during or after application. This preliminary inclusion of crosslinking capability in the liquid binder allows the material to be applied easily in liquid form while automatically developing the crosslinked network structure that provides crack resistance and weather durability during the curing process
3Ease of manufacture
If aluminum trihydroxide is used as a cheaper and non-abrasive alternative, then cost and abrasiveness improve, but thermal conductivity decreases requiring high loadings
Solution Approach 1:
The patent optimizes the particle size parameters of aluminum trihydroxide filler and controls its loading (80-95 wt%) to maximize thermal conductivity achievement. By carefully controlling filler morphology and size distribution along with the binder composition, the patent achieves the required thermal conductivity (2 W/m·K or higher) using cost-effective ATH rather than expensive high-conductivity fillers like boron nitride
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 composition achieves high thermal conductivity (2 W/m·K or higher) and passes cyclic bleeding tests, demonstrating improved weather resistance and stability.
Implementation Method 1
thermal interface material composition... achieves high thermal conductivity (2 W/m·K or higher)... filled with thermally conductive fillers... aluminum trihydroxide
Implementation Method 2
urethane based binder component... non-reactive polyurethane prepolymer... binds... aluminum trihydroxide
Data Source
AI summary
Disclosed herein are thermal interface materials comprising non-reactive polyurethane prepolymer and high loading of aluminum trihydroxide and the use thereof in battery powered vehicles.