White Pigment Ink Set With pH-Triggered Voids for Adhesion

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Solution Overview

Problem

Existing ink technologies struggle to achieve a balance between high covering property and adhesiveness of images on impermeable base materials, particularly when using white pigments, leading to decreased adhesion due to excessive void formation.

Innovation Solution

An ink set comprising a treatment liquid with a pH of 4.5 or less or 9.5 or greater, and an ink containing a compound A that generates gas at similar pH levels, along with a resin and white pigment, where the ratio of white pigment to compound A is controlled to maintain adhesiveness while forming appropriate voids for improved covering.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If an ink containing white pigment is used to record an image, then the covering property is improved, but the adhesiveness to impermeable base material deteriorates

Engineering Contradiction:
Improvecovering propertyVSAvoidadhesiveness
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The patent applies parameter changes by precisely controlling the pH of the ink within 4.5-9.5 and the ratio of white pigment to compound A within 10-100. This ensures that when the ink contacts the treatment liquid, gas is generated at a controlled rate, forming appropriate voids that improve covering property while maintaining adhesiveness. The pH parameter control prevents excessive gas generation that would cause poor adhesion, while still achieving sufficient covering.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent utilizes porous material principles by intentionally forming voids within the ink film through controlled gas generation. These voids create a porous structure that enhances light scattering and covering property. The void formation is controlled by the pH-dependent gas-generating reaction between compound A and the treatment liquid, creating an optimal balance between covering and adhesion.

Inventive Principle:
Principle #31Porous materials

2Reliability

If the pH of the ink is adjusted to generate gas for improving covering property, then the covering property is improved, but the adhesiveness deteriorates due to excessive void formation

Engineering Contradiction:
Improvecovering propertyVSAvoidadhesiveness
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The patent resolves this contradiction through precise parameter control: pH is maintained within 4.5-9.5 and the white pigment to compound A ratio within 10-100. These parameter ranges ensure that gas generation occurs at a moderate rate upon contact with treatment liquid, forming sufficient voids for covering property while preventing excessive void formation that would compromise adhesiveness.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent applies partial action by using a moderate amount of compound A relative to white pigment (ratio of 10-100). This controlled stoichiometry ensures that gas is generated in sufficient quantity to create voids for covering property, but not in excess quantity that would create too many voids and reduce adhesion. The partial gas generation achieves the optimal balance.

Inventive Principle:
Principle #16Partial or excessive action

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 set achieves excellent covering properties and adhesiveness to impermeable base materials by controlling void formation, enhancing image visibility and stability on non-porous surfaces.

Implementation Method 1

an ink containing a compound A which generates gas in an environment of a pH of 4.5 or less or 9.5 or greater

Methodology Applied
Scientific EffectGas generation through pH-dependent chemical reaction: Chemical Bonding

Data Source

PatentEP3950355B1Ink set, use of ink set, method for recording image, and object with recorded image
Publication Date: 2026.03.11 FUJIFILM CORP
  • EP3950355B1 patent drawingFigure 1
  • EP3950355B1 patent drawingFigure 2
  • EP3950355B1 patent drawing

AI summary

Provided are an ink set capable of recording an image having an excellent covering property and excellent adhesiveness to an impermeable base material, an image recording method, and an image recorded material. The ink set is an ink set including a treatment liquid having a pH of 4.5 or less or 9.5 or greater, and an ink containing a compound A which generates gas in an environment of a pH of 4.5 or less or 9.5 or greater, a resin, water, and a white pigment and having a pH of greater than 4.5 and less than 9.5, in which a ratio of a content mass of the white pigment to a content mass of the compound A in the ink is 1 or greater and 160 or less.