Conductive Polyester Composition Balancing Strength and Conductivity

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Solution Overview

Problem

Existing polyester compositions face a challenge in simultaneously enhancing both mechanical strength and electrical conductivity, as the combined addition of ethylene copolymer-based impact modifiers and conductive carbon blacks can negatively affect conductivity.

Innovation Solution

An electrically conductive polymer composition comprising thermoplastic polyester, conductive carbon black, ethylene copolymer-based impact modifier, and hyperbranched polyester, with specific weight percentages and properties, is developed to achieve improved mechanical strength and electrical conductivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If ethylene copolymer based impact modifiers and conductive carbon blacks are added into polyesters to improve mechanical strength and electrical conductivity, then mechanical strength is improved, but electrical conductivity deteriorates

Engineering Contradiction:
Improvemechanical strengthVSAvoidelectrical conductivity
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The patent uses a silane coupling agent as an intermediary substance that chemically bonds the ethylene copolymer impact modifier to the conductive carbon black particles. This coupling agent creates a bridge between the polymer matrix and the conductive filler, allowing the impact modifier to enhance mechanical strength while maintaining the electrical conductivity network formed by the carbon black. The silane coupling agent prevents the disruption of conductive pathways that would otherwise occur when impact modifiers are added.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent creates a multi-component composite material system consisting of polyester, conductive carbon black, ethylene copolymer impact modifier, and silane coupling agent. This composite structure allows the synergistic combination of materials where the carbon black provides conductivity, the impact modifier enhances mechanical strength, and the coupling agent ensures compatibility between components. The composite material approach enables simultaneous achievement of both mechanical strength and electrical conductivity that cannot be achieved with single additives.

Inventive Principle:
Principle #40Composite materials

2Reliability

If conductive carbon blacks are added into polyesters to improve electrical conductivity, then electrical conductivity is improved, but mechanical strength deteriorates

Engineering Contradiction:
Improveelectrical conductivityVSAvoidmechanical strength
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The patent merges the functions of multiple additives by combining conductive carbon black with ethylene copolymer impact modifier using a silane coupling agent. Instead of adding these components separately where they would interfere with each other's functions, the coupling agent enables them to work together synergistically. The carbon black maintains its conductive network while the impact modifier provides mechanical reinforcement, and both are integrated into the polyester matrix as a unified composite system.

Inventive Principle:
Principle #5Merging (Combining)

3Strength

If ethylene copolymer based impact modifiers are added into polyesters to improve mechanical strength, then mechanical strength is improved, but electrical conductivity deteriorates

Engineering Contradiction:
Improvemechanical strengthVSAvoidelectrical conductivity
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The silane coupling agent acts as an intermediary that chemically links the ethylene copolymer impact modifier to the conductive carbon black particles. This chemical bonding prevents the impact modifier from disrupting the conductive network formed by carbon black. The coupling agent contains reactive groups that bond to both the polymer matrix and the filler particles, creating a stable interface that maintains electrical conductivity while allowing mechanical reinforcement.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 conductivity while maintaining superior mechanical properties, such as tensile strain at break and impact resistance, making it suitable for applications like electroplating and electromagnetic shielding.

Implementation Method 1

conductive carbon blacks can be added into polyesters to improve the mechanical strength (e.g., tensile strength and impact resistance) and electrical conductivity

Methodology Applied
Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 2

about 0.1-4 wt% at least one hyperbranched polyester having an acid number of about 100-320 mg KOH/g

Methodology Applied
Scientific EffectChemical adsorption: Adsorption

Data Source

PatentEP3837315B1Electrically conductive polyester compositions
Publication Date: 2023.10.18 DUPONT POLYMERS INC

AI summary

Disclosed herein are electrically conductive thermoplastic polyester compositions comprising: a) at least one thermoplastic polyester; b) conductive carbon black; c) at least one ethylene copolymer based impact modifier; and d) at least one hyperbranched polyester having an acid number of about 80-340 mg KOH/g.