Pigment Ink Composition for Redispersibility and Storage Stability

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Solution Overview

Problem

Inkjet printing using pigments faces challenges with redispersibility and storage stability due to pigment aggregation, leading to sedimentation and clogging issues, which affect printing characteristics and nozzle discharge.

Innovation Solution

An ink composition comprising a pigment, a specific polymer formed from selected monomers, a styrene-butadiene resin, a water-soluble organic solvent, and a nonionic surfactant, optimized in terms of mass percentages and surface tension, to enhance redispersibility and storage stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a water-insoluble coloring agent such as a pigment is used, then durability to light, ozone, and water is improved, but redispersibility deteriorates when the ink dries

Engineering Contradiction:

Improvedurability to light, ozone, and waterVSAvoidredispersibility

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

A polymer dispersing agent is introduced as an intermediary substance between the pigment particles and the aqueous medium. This dispersing agent has both hydrophobic groups that interact with the pigment surface and hydrophilic groups that interact with water, enabling the pigment to remain dispersed in the aqueous ink and facilitating redispersibility after drying.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The ink composition uses a composite approach by combining pigment particles with a polymer dispersing agent system. The dispersing agent forms a composite structure where the polymer coating on pigment particles provides both stability in the aqueous medium and redispersibility upon contact with water after drying.

Inventive Principle:

Principle #40Composite materials

2Reliability

If a pigment is used as a coloring agent, then toughness to light, ozone, and water is improved, but storage stability deteriorates due to sedimentation

Engineering Contradiction:

Improvetoughness to light, ozone, and waterVSAvoidstorage stability

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The polymer dispersing agent acts as a mediator that prevents direct interaction between pigment particles, reducing aggregation and sedimentation. The polymer coating provides steric stabilization, keeping pigment particles evenly distributed throughout the ink during storage.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention optimizes parameters including the molecular weight, composition, and concentration of the polymer dispersing agent. By carefully controlling these parameters, the ink achieves optimal balance between pigment dispersion stability during storage and redispersibility after drying.

Inventive Principle:

Principle #35Parameter changes

3Manufacturing precision

If pigment particles aggregate, then printing characteristics deteriorate, but nozzle clogging is avoided

Engineering Contradiction:

Improveprinting characteristicsVSAvoidnozzle clogging

Core Design Contradiction:

Manufacturing precisionVSObject-generated harmful factors

Solution Approach 1:

The polymer dispersing agent serves as a protective intermediary that prevents pigment aggregation while maintaining individual particle separation. This ensures smooth nozzle discharge without clogging while preserving the printing quality that requires uniform pigment distribution.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention controls pigment particle size distribution and polymer dispersing agent concentration to optimize the balance between preventing nozzle clogging and maintaining printing characteristics. The particle size is kept within a specific range to ensure easy nozzle passage while the polymer coating maintains dispersion stability.

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 ink composition achieves excellent redispersibility and storage stability, preventing pigment aggregation and ensuring consistent printing performance without nozzle clogging, while maintaining high-quality dyeing with improved light and water resistance.

Implementation Method 1

an nonionic surfactant... at 25° C., the surface tension is 20 to 40 mN/m

Methodology Applied

Scientific EffectSurface tension reduction: Surfactant

Implementation Method 2

a polymer D formed from at least two types of monomers selected from a group consisting of a monomer A, a monomer B and a monomer C... excellent in redispersibility and storage stability

Methodology Applied

Scientific EffectSteric stabilization: Dispersion (of waves)

Data Source

PatentUS9181446B2Ink composition and printing method

Publication Date: 2015.11.10 NIPPON KAYAKU CO LTD

AI summary

Provided are: an ink composition for ink-jet printing use, which has good re-dispersibility after being dried and does not undergo the change in properties of the ink even when stored for a long period; and an ink-jet printing method and a dyeing method each using the ink composition. The ink composition according to the present invention comprises: a pigment; water; a polymer (D) composed of at least two monomers independently selected from the group consisting of a monomer (A), a monomer (B) and a monomer (C) respectively represented by specific formulae; a styrene-butadiene resin; a water-soluble organic solvent; and a nonionic surfactant.