Thermoplastic Resin Composition with Graphite Flakes for Thermal Conductivity

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Solution Overview

Problem

Thermoplastic resins used in electronic devices face challenges in achieving high thermal conductivity while maintaining moldability and insulating properties, as high concentrations of thermally conductive inorganic fillers can lead to electrical conductivity, mold wear, and reduced processability.

Innovation Solution

A thermoplastic resin composition with a specific molecular structure, including units with biphenyl groups and divalent linear substituents, combined with an inorganic filler, which enhances thermal conductivity and allows for lower processing temperatures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If a large amount of highly thermally conductive inorganic matter is mixed into a thermoplastic resin, then thermal conductivity is improved, but electrical insulation deteriorates and the composition becomes electrically conductive

Engineering Contradiction:

Improvethermal conductivityVSAvoidelectrical insulation

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

The patent applies local quality by using graphite flake particles with specific aspect ratios (length-to-thickness ratio of 10 or more) to create localized thermal conduction paths while maintaining electrical insulation. The anisotropic structure of graphite flakes allows heat conduction in the plane of the flakes without establishing continuous electrical conduction paths through the resin matrix.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent changes the parameter of inorganic filler geometry from conventional shapes to specifically shaped graphite flake particles with controlled aspect ratios. This parameter change enables achieving high thermal conductivity at lower filler concentrations (5-30 vol%) compared to conventional fillers, thereby maintaining electrical insulation while improving thermal conductivity.

Inventive Principle:

Principle #35Parameter changes

2Temperature

If a large amount of ceramic filler such as alumina is mixed into a thermoplastic resin, then thermal conductivity is improved, but mold wear increases due to high hardness of the filler

Engineering Contradiction:

Improvethermal conductivityVSAvoidmold wear

Core Design Contradiction:

TemperatureVSEase of manufacture

Solution Approach 1:

The patent employs graphite flake particles which, while having high thermal conductivity, are softer than alumina and other ceramic fillers. This substitution reduces mold wear and extends mold life, making the manufacturing process more sustainable and cost-effective over time.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Temperature

If a large amount of inorganic matter is mixed into a thermoplastic resin, then thermal conductivity is improved, but processability deteriorates due to high density of the filler

Engineering Contradiction:

Improvethermal conductivityVSAvoidprocessability

Core Design Contradiction:

TemperatureVSEase of manufacture

Solution Approach 1:

The patent uses graphite flake particles with specific aspect ratios to create efficient thermal conduction networks at lower filler concentrations. This local optimization of filler geometry allows achieving high thermal conductivity without the high filler loads that cause processing difficulties and increased density.

Inventive Principle:

Principle #3Local quality

4Temperature

If liquid crystal polyester is oriented by external fields to achieve high thermal conductivity, then thermal conductivity in a specific direction is improved, but the processing becomes difficult due to high magnetic flux density requirements

Engineering Contradiction:

Improvethermal conductivityVSAvoidprocessing difficulty

Core Design Contradiction:

TemperatureVSEase of manufacture

Solution Approach 1:

The patent replaces the need for high magnetic flux density fields (3 tesla or more) with a mechanical approach using graphite flake particles that inherently provide anisotropic thermal conductivity. The flakes are incorporated into the resin matrix and naturally orient during processing, eliminating the need for complex high-field magnetic orientation equipment and procedures.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 while maintaining electrical insulation and processability, enabling the production of thermally conductive sheets suitable for electronic devices.

Implementation Method 1

the present invention relates to a thermoplastic resin composition which simultaneously has high thermal conductivity, favorable moldability, and a favorable insulating property due to a synergistic effect which is brought about by using, in combination, (i) a highly thermally conductive matrix resin and (ii) a thermally conductive inorganic filler

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS11572437B2Thermoplastic resin, thermoplastic resin composition, and heat conductive sheet

Publication Date: 2023.02.07 KANEKA CORP

AI summary

A thermoplastic resin (A) including, in its main chain structure, a unit (i) having a biphenyl group, a unit (ii) having a substituent biphenyl group, a unit (iii) having a specific number of atoms in its main chain, and a unit (iv) having a specific number of atoms in its main chain provides a thermoplastic resin which has a low liquid crystal phase transition temperature and a low isotropic phase transition temperature, is highly thermally conductive, and can be processed by molding at a low melting temperature.