Conductive Pigment Paste Dispersion for High-Concentration Stability

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Solution Overview

Problem

Existing methods for manufacturing conductive pigment pastes struggle with achieving excellent pigment dispersibility and storage stability, especially at high pigment concentrations and viscosities, which affects the conductivity and performance of coating films.

Innovation Solution

A method involving the dispersion of a pigment dispersion resin with polar functional groups and carbon nanotubes or conductive carbon using specific dispersers, along with a solvent that matches the resin's solubility parameter, and pre-mixing with a media-less disperser to create a conductive pigment paste with improved dispersibility and stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If the pigment concentration is increased to reduce solvent usage and drying energy, then the energy consumption decreases, but the pigment dispersibility deteriorates

Engineering Contradiction:
Improvedrying energyVSAvoidpigment dispersibility
Core Design Contradiction:
Loss of energyVSManufacturing precision

Solution Approach 1:

A pigment dispersion resin with specific polar functional groups (9-23 mmol/g) acts as an intermediary between the conductive pigment and solvent, enabling high pigment concentration (5-50 mass%) while maintaining uniform dispersion. The resin prevents aggregation through its polar groups that interact with both pigment and solvent molecules.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The solubility parameter difference between pigment dispersion resin and solvent is controlled to be within 2.0 (cal/cm³)¹/², ensuring optimal compatibility. This parameter control allows high pigment concentration while maintaining dispersibility, resolving the contradiction between concentration and dispersion quality.

Inventive Principle:
Principle #35Parameter changes

2Quantity of substance

If the pigment concentration is increased to create a highly concentrated paste, then the solvent usage decreases, but the storage stability deteriorates

Engineering Contradiction:
Improvepigment concentrationVSAvoidstorage stability
Core Design Contradiction:
Quantity of substanceVSStability of the object's composition

Solution Approach 1:

The pigment dispersion resin serves as a stabilizing intermediary that prevents pigment aggregation during storage. Its polar functional groups (9-23 mmol/g) provide steric and electrostatic stabilization, maintaining uniform dispersion even at high pigment concentrations (5-50 mass%) over extended storage periods.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention creates a composite paste system combining conductive pigment, pigment dispersion resin with specific polar group concentration, and solvent in optimized ratios. This composite structure ensures both high pigment concentration and excellent storage stability through synergistic interactions among components.

Inventive Principle:
Principle #40Composite materials

3Reliability

If the pigment concentration is increased to improve conductivity, then the conductive performance improves, but the pigment dispersibility deteriorates

Engineering Contradiction:
Improveconductive performanceVSAvoidpigment dispersibility
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The pigment dispersion resin with polar functional groups (9-23 mmol/g) acts as a mediator that maintains individual pigment particle separation even at high concentrations (5-50 mass%). This prevents aggregation while preserving conductive pathways, achieving both excellent dispersibility and conductive performance in the coating film.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

By controlling the solubility parameter difference between resin and solvent to within 2.0 (cal/cm³)¹/² and optimizing polar functional group concentration (9-23 mmol/g), the system achieves optimal balance between pigment-wetting capability and dispersibility maintenance, enabling high pigment concentration with excellent conductive performance.

Inventive Principle:
Principle #35Parameter changes

4Quantity of substance

If a high viscosity paste is used to reduce solvent content, then the solvent usage decreases, but the uniform dispersion deteriorates

Engineering Contradiction:
Improvesolvent contentVSAvoiduniform dispersion
Core Design Contradiction:
Quantity of substanceVSManufacturing precision

Solution Approach 1:

The pigment dispersion resin with specific polar functional group concentration (9-23 mmol/g) acts as a lubricating intermediary between pigment particles, reducing inter-particle friction and enabling uniform dispersion even in high viscosity, low solvent formulations. This allows minimal solvent content while maintaining excellent dispersibility.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

By optimizing the solubility parameter match between resin and solvent (difference within 2.0 (cal/cm³)¹/²) and controlling polar group concentration, the system achieves reduced solvent content (5-95 mass%) while maintaining low enough viscosity for uniform dispersion through enhanced resin-pigment interaction.

Inventive Principle:
Principle #35Parameter changes

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 method results in a conductive pigment paste that maintains excellent pigment dispersibility and storage stability, even at high concentrations, leading to enhanced conductivity and performance of the coating film.

Implementation Method 1

dispersing a paste containing a pigment dispersion resin (A), a conductive pigment (B), and a solvent (C) using at least one type of disperser selected from the group consisting of a bead mill

Methodology Applied
Scientific EffectMechanical grinding: Mechanical Force

Implementation Method 2

dispersing a paste containing a pigment dispersion resin (A), a conductive pigment (B), and a solvent (C) using at least one type of disperser selected from the group consisting of a bead mill, a homogenizer, an ultrasonic disperser

Methodology Applied
Scientific EffectUltrasonic vibration: Ultrasonic Vibration

Implementation Method 3

The pigment dispersion resin (A) includes at least one polar functional group selected from the group consisting of an amide group, an imide group, an ether group, a hydroxyl group, a carboxyl group, a sulfonate group, a phosphate group, a silanol group, and an amino group

Methodology Applied
Scientific EffectPolar interaction: Ion Repulsion/Attraction

Data Source

PatentUS20240158646A1Method for manufacturing conductive pigment paste
Publication Date: 2024.05.16 KANSAI PAINT CO LTD

AI summary

The present invention relates to a solution to provide a conductive pigment paste that exhibits excellent pigment dispersibility and storage stability even as a paste with a high pigment concentration and/or high viscosity, and can be used to form a coating film excelling in conductivity and other properties. The present invention provides a method for manufacturing a conductive pigment paste. The method includes dispersing a paste containing a pigment dispersion resin (A), a conductive pigment (B), and a solvent (C) using at least one type of disperser selected from the group consisting of a bead mill, a homogenizer, an ultrasonic disperser, a kneader, an extruder, and a planetary mixer. The pigment dispersion resin (A) includes at least one polar functional group selected from the group consisting of an amide group, an imide group, an ether group, a hydroxyl group, a carboxyl group, a sulfonate group, a phosphate group, a silanol group, and an amino group, and the concentration of the polar functional group in the pigment dispersion resin (A) is from 9 to 23 mmol/g. The conductive pigment (B) contains carbon nanotubes (B-1) and/or a conductive carbon (B-2) having an average primary particle size from 10 to 80 nm. A solubility parameter δA of the pigment dispersion resin (A) and a solubility parameter δC of the solvent (C) satisfy a relationship of |δA−δC|<2.1.