Thermally Conductive Silicone Composition for High-Temperature Adhesion
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Solution Overview
Problem
Traditional thermally conductive silicone compositions used in high-temperature environments, such as those found in vehicle engine rooms, experience increased hardness and peel-off issues due to unreacted components and reduced reactivity, leading to reduced heat resistance and flexibility.
Innovation Solution
A thermally conductive composition comprising organopolysiloxane with alkenyl groups, organo-hydrogen polysiloxane with hydrosilyl groups, a polysiloxane compound with methacryloyl groups, and a hydrosilylation catalyst, where the molecular weight of the methacryloyl group is smaller than the alkenyl group, promoting controlled cross-linking and reducing hardness increases even at high temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional thermally conductive silicone composition is used in high-temperature environment (150°C or higher), then initial thermal conductivity is achieved, but hardness increases over time causing peel-off from heating element and heat-dissipating element
Solution Approach 1:
The invention changes the molecular weight parameter of the polysiloxane compound to resolve the contradiction. Specifically, it uses a polysiloxane compound with a methacryloyl group having a weight average molecular weight of 10,000 or less, which is smaller than that of the organopolysiloxane with alkenyl groups. This parameter change ensures complete reaction at high temperatures, preventing hardness increase and maintaining adhesion strength while preserving thermal conductivity.
Solution Approach 2:
The invention creates a composite curing system combining two different polysiloxane compounds with distinct functional groups (alkenyl and methacryloyl). This composite approach allows the alkenyl-containing polysiloxane to provide initial crosslinking and structural framework, while the methacryloyl-containing polysiloxane with lower molecular weight ensures complete reaction and eliminates unreacted components, thereby maintaining both thermal conductivity and adhesion at high temperatures.
2Ease of operation
If molecular weight of polysiloxane is increased to reduce cross-linking density and maintain flexibility, then flexibility is improved, but reactivity decreases leading to unreacted components at high temperature
Solution Approach 1:
The invention segments the polysiloxane components into two distinct functional groups: one with alkenyl groups for providing flexibility through lower cross-linking density, and another with methacryloyl groups having smaller molecular weight for ensuring high reactivity. This segmentation allows each component to fulfill its specific role without compromising the other, achieving both flexibility and complete reaction at high temperatures.
Solution Approach 2:
The invention applies parameter changes by controlling the molecular weight of the methacryloyl-containing polysiloxane to be 10,000 or less, which is specifically smaller than the molecular weight of the alkenyl-containing polysiloxane. This parameter optimization ensures that the lower molecular weight component maintains high reactivity and mobility for complete reaction, while the higher molecular weight component provides the desired flexibility.
3Reliability
If functional group concentration is increased to improve heat resistance, then thermal stability is improved, but hardness increases causing peel-off
Solution Approach 1:
The invention resolves this contradiction by changing the molecular weight parameter of the polysiloxane compound rather than simply adjusting functional group concentration. By using a methacryloyl-containing polysiloxane with molecular weight of 10,000 or less, the invention achieves complete reaction at high temperatures, ensuring heat resistance without creating excessive cross-linking density that would cause hardness increase and peel-off.
Solution Approach 2:
The composite system combines polysiloxane with alkenyl groups (providing flexible crosslinking) and polysiloxane with methacryloyl groups of lower molecular weight (providing complete reaction and heat resistance). This composite approach achieves heat resistance through complete reaction rather than through high functional group concentration alone, thereby maintaining adhesion 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 composition maintains flexibility and heat resistance under high temperatures, preventing peel-off and ensuring long-term adhesion to heating and dissipating elements.
Implementation Method 1
organopolysiloxane having an alkenyl group, organo-hydrogen polysiloxane having a hydrosilyl group, and a hydrosilylation catalyst
Implementation Method 2
curable liquid types of thermally conductive compositions... used as thermally conductive members, such as heat-dissipating gap fillers for conducting heat generated from a heating element to a heat-dissipating element
Data Source
AI summary
A thermally conductive composition comprising: (A) an organopolysiloxane having an alkenyl group, (B) an organopolysiloxane having a hydrosilyl group, (C) a thermally conductive filler, (D) a polysiloxane compound having a methacryloyl group, and (E) a hydrosilylation catalyst, a weight average molecular weight Mwd of the (D) being smaller than a weight average molecular weight Mwa of the (A).