Thermally Conductive Silicone Rubber Composition Oil Bleed Reduction
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Solution Overview
Problem
Existing thermally conductive silicone rubber compositions contaminate surrounding substrates due to oil fraction bleeding and low-boiling fraction volatilization during curing, which are not adequately reduced in previous formulations.
Innovation Solution
A thermally conductive silicone rubber composition is developed with specific organopolysiloxane and organohydrogenpolysiloxane components, an adhesion promoter, and a thermally conductive filler, optimized to minimize oil fraction bleeding and low-boiling fraction volatilization through controlled viscosity, cyclic siloxane content, and catalyst usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional thermally conductive silicone rubber compositions are used, then thermal conductivity is achieved, but oil fraction bleeding and low-boiling fraction volatilization contaminate surrounding substrates
Solution Approach 1:
The patent applies parameter changes by carefully controlling the viscosity of the organopolysiloxane (10-500,000 mPa·s) and limiting cyclic siloxane content (≤1,000 ppm) to prevent oil fraction bleeding and low-boiling fraction volatilization while maintaining thermal conductivity. This resolves the contradiction by adjusting physical parameters of the base polymer to eliminate harmful emissions without sacrificing thermal performance.
Solution Approach 2:
The patent uses composite materials by combining organopolysiloxane with specific viscosity ranges, organohydrogenpolysiloxane, adhesion promoters, and thermally conductive fillers (alumina, boron nitride, silicon carbide) to create a formulation that achieves both low contamination and high thermal conductivity. The composite structure allows synergistic effects where each component contributes to either reducing harmful fractions or enhancing thermal properties.
2Stability of the object's composition
If silicone rubber composition is cured, then crosslinking and structural stability are achieved, but oil fraction bleeds out and low-boiling fraction volatilizes
Solution Approach 1:
The patent applies preliminary action by pre-selecting organopolysiloxane with controlled viscosity (10-500,000 mPa·s) and low cyclic siloxane content (≤1,000 ppm) before curing. This preliminary selection of base polymer parameters prevents oil fraction bleeding and low-boiling fraction volatilization during the subsequent curing process, while still achieving stable crosslinked structure through the addition of organohydrogenpolysiloxane and catalyst.
3Temperature
If thermally conductive filler is added to improve thermal conductivity, then heat dissipation performance increases, but composition complexity and processing difficulty increase
Solution Approach 1:
The patent applies local quality by selecting specific types of thermally conductive fillers (alumina, boron nitride, silicon carbide) with defined particle size ranges and incorporating them into a carefully formulated polymer matrix. This targeted approach ensures high thermal conductivity in critical areas while maintaining overall composition manageability through controlled polymer viscosity and standardized filler specifications.
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 effectively reduces oil fraction bleeding and low-boiling fraction volatilization, enhancing handling characteristics and adhesiveness while maintaining excellent thermal conductivity and physical properties.
Implementation Method 1
an organopolysiloxane that has at least two silicon-bonded alkenyl groups in each molecule (A), an organohydrogenpolysiloxane that has at least two silicon-bonded hydrogen atoms in each molecule (B)... a platinum group metal-type catalyst (E)
Implementation Method 2
a thermally conductive filler (D)... alumina, boron nitride, or silicon carbide
Data Source
AI summary
A thermally conductive silicone rubber composition comprises: (A) an organopolysiloxane that contains at least two silicon-bonded alkenyl groups in each molecule, that does not contain silicon-bonded hydroxyl and alkoxy groups, and that has a content of cyclic siloxanes having from 4 to 20 siloxane units of not more than 1,000 ppm in mass units; (B) an organopolysiloxane that contains at least two silicon-bonded hydrogen atoms in each molecule and that does not contain silicon-bonded alkenyl, hydroxyl group, and alkoxy groups; (C) an adhesion promoter; (D) a thermally conductive filler; and (E) a hydrosilylation reaction catalyst; wherein the total quantity of components (B) and (C) is from 0.5 to 10 mass% of the total quantity of components (A), (B), and (C). The composition is characterized by reduced oil fraction that bleeds out during the course of curing, and by reduced low-boiling fraction that volatilizes during the course of curing.