Thermally Conductive Silicone Composition for Filler Stability

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Solution Overview

Problem

Existing thermally conductive silicone compositions face issues with filler precipitation, flexibility, and storage stability, leading to uneven quality and increased thermal resistance, particularly in applications requiring high flexibility and heat dissipation.

Innovation Solution

A thermally conductive silicone composition containing specific components: an alkenyl group-containing organopolysiloxane, a hydrosilyl group-containing organopolysiloxane, a silanol group-containing organopolysiloxane with controlled viscosity, a thermally conductive filler with defined BET surface area and particle size, and a cross-linking agent, which enhances flexibility and suppresses filler precipitation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a large amount of spherical thermally conductive filler is mixed in the composition to achieve high thermal conductivity, then thermal conductivity is improved, but the filler is likely to precipitate leading to poor storage stability

Engineering Contradiction:
Improvethermal conductivityVSAvoidstorage stability
Core Design Contradiction:
ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent introduces a specific polymer as an intermediary substance between the spherical thermally conductive filler and the silicone composition matrix. This polymer modifies the interaction between filler particles and the base material, preventing filler precipitation while maintaining high thermal conductivity. The polymer acts as a mediator that stabilizes the filler distribution without compromising the thermal performance.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Ease of operation

If a low viscosity polymer is used to achieve high flexibility, then flexibility is improved, but the thermally conductive filler is likely to precipitate with time

Engineering Contradiction:
ImproveflexibilityVSAvoidfiller precipitation resistance
Core Design Contradiction:
Ease of operationVSStability of the object's composition

Solution Approach 1:

The patent modifies the viscosity parameter of the polymer used in the composition. By carefully selecting a polymer with specific viscosity characteristics, the formulation achieves optimal balance between flexibility and filler stability. The viscosity parameter is tuned to provide sufficient fluidity for flexibility while creating a matrix structure that prevents filler particle settling over time.

Inventive Principle:
Principle #35Parameter changes

3Stability of the object's composition

If aluminum hydroxide filler is used to suppress precipitation, then storage stability is improved, but the flexibility of cured products becomes insufficient

Engineering Contradiction:
Improveprecipitation suppressionVSAvoidflexibility
Core Design Contradiction:
Stability of the object's compositionVSEase of operation

Solution Approach 1:

The patent employs a composite filler system combining aluminum hydroxide with other thermally conductive materials such as aluminum oxide or boron nitride. This composite approach allows the aluminum hydroxide to provide precipitation suppression while the other filler components contribute to thermal conductivity and maintain flexibility. The synergistic combination of different filler materials resolves the contradiction between stability and flexibility.

Inventive Principle:
Principle #40Composite materials

4Stability of the object's composition

If polysaccharides are used as precipitation-preventing material, then filler precipitation is suppressed, but thermal decomposition occurs at high temperatures reducing flexibility and thermal conductivity

Engineering Contradiction:
Improveprecipitation suppressionVSAvoidheat resistance
Core Design Contradiction:
Stability of the object's compositionVSReliability

Solution Approach 1:

The patent replaces polysaccharide-based precipitation prevention materials with synthetic polymer alternatives that do not suffer from thermal decomposition. The synthetic polymer, while potentially less biodegradable, provides long-term stability across a wider temperature range without decomposing. This substitution trades off environmental considerations for improved thermal reliability and consistent performance at elevated temperatures.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

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 flexibility, improved storage stability, and reduced thermal resistance, ensuring consistent quality and effective heat dissipation properties in thermally conductive members.

Implementation Method 1

a silanol group-containing organopolysiloxane having a viscosity, at 25°C, of 10 mPa·s or more and 500 mPa·s or less... the content of the silanol groups in the component (C) is 1% by mass to 8% by mass

Methodology Applied
Scientific EffectHydrogen bonding:

Implementation Method 2

a component (A) that is an alkenyl group-containing organopolysiloxane; a component (B) that is an organopolysiloxane having two or more hydrosilyl groups within one molecule... a component (D) that is an addition reaction catalyst

Methodology Applied
Scientific EffectAddition cross-linking reaction:

Implementation Method 3

a component (E) that is at least one or more types of thermally conductive filler selected from the group consisting of a metal, a metal oxide, a metal hydroxide, a metal nitride, and a metal carbide... high heat dissipation properties can be imparted

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentEP4499753B1Thermally conductive silicone composition and method for producing thermally conductive member using the composition
Publication Date: 2025.10.08 WACKER CHEMIE AG

AI summary

Provided is a thermally conductive silicone composition for obtaining a thermally conductive member having high flexibility and excellent heat dissipation properties, the thermally conductive silicone composition having excellent storage stability and heat resistance. The thermally conductive silicone composition according to the present invention is a thermally conductive silicone composition containing : a component (A) that is an alkenyl group-containing organopolysiloxane; a component (B ) that is an organopolysiloxane having two or more hydrosilyl groups within one molecule; a component (C) that is a silanol group-containing organopolysiloxane having a viscosity, at 25°C, of 10 mPa.s or more and 500 mPa.s or less; a component ( D) that is an addition reaction catalyst; a component (E) that is a thermally conductive filler having a BET speci fic surface area of 30 m2/g or less and an average particle diameter of 1 to 100 µm; and a component (F) that is a cross-linking agent, wherein the content of a filler having a BET specific surface area of 50 m2/g or more in the composition is 3 parts by mass or less relative to 100 parts by mass of a total amount of the components (A) and (B).