Ink Composition Crystallinity Control for Color and Light Resistance

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Solution Overview

Problem

Inkjet printers face challenges in achieving good color reproducibility, abrasion resistance, durability, light resistance, and gloss with current inks, as dye-based inks lack water resistance and pigment inks suffer from color degradation and inferior gloss compared to dye inks.

Innovation Solution

An ink composition using a pigment with reduced crystallinity, maintained crystalline structure, and specific particle size, combined with a hydrosoluble solvent and water, is developed, utilizing a microreactor for pigment precipitation and a dispersing agent to enhance dispersion stability and inkjet printing performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If pigment is used as coloring agent to improve light resistance and water resistance, then durability is improved, but coloring quality deteriorates due to beam coherence and multiple reflections

Engineering Contradiction:
Improvelight resistanceVSAvoidcoloring quality
Core Design Contradiction:
ReliabilityVSIllumination intensity

Solution Approach 1:

The patent applies parameter changes by precisely controlling the crystallinity of the pigment particles. By adjusting the crystallinity index to a specific range (0.15-0.35), the invention optimizes the balance between light resistance and coloring quality. This parameter optimization reduces unwanted light scattering while maintaining the pigment's inherent durability advantages.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention uses composite materials by combining pigment particles with specific crystallinity characteristics and resin coatings. The resin coating serves multiple functions: it protects the pigment particles, enhances dispersion stability, and modifies optical properties to reduce beam coherence effects, thereby improving coloring quality while preserving light resistance.

Inventive Principle:
Principle #40Composite materials

2Stability of the object's composition

If pigment particulates coated with resin are used to improve fixing property and gas resistance, then dispersion stability is improved, but gloss deteriorates compared to dye ink

Engineering Contradiction:
Improvedispersion stabilityVSAvoidgloss
Core Design Contradiction:
Stability of the object's compositionVSIllumination intensity

Solution Approach 1:

The patent optimizes the resin coating thickness and composition parameters to achieve the desired balance. By controlling the resin content and molecular weight, the invention maintains adequate dispersion stability while minimizing the negative impact on gloss. The resin layer is optimized to be thin enough to allow light penetration for gloss while providing sufficient protection for dispersion stability.

Inventive Principle:
Principle #35Parameter changes

3Illumination intensity

If pigment crystallinity is reduced to improve coloring quality, then color saturation is improved, but light resistance and gas resistance deteriorate drastically

Engineering Contradiction:
Improvecoloring qualityVSAvoidlight resistance
Core Design Contradiction:
Illumination intensityVSReliability

Solution Approach 1:

The patent applies parameter changes by precisely controlling the crystallinity index within a specific range (0.15-0.35). This optimized crystallinity level is sufficient to improve coloring quality by reducing beam coherence effects, while maintaining enough crystalline structure to preserve the pigment's light resistance and gas resistance properties. The resin coating further protects the pigment particles, ensuring durability is maintained even at reduced crystallinity.

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 improved color quality, light resistance, and image gloss without degrading pigment characteristics, enabling high-saturation and bright images on various paper types.

Implementation Method 1

the coloring of the pigment ink is degraded by coherence of beams of light having different wavelengths and phases produced by multiple reflections of the beams of light within the pigment

Methodology Applied
Scientific EffectLight scattering: Scattering

Implementation Method 2

utilizing a microreactor for pigment precipitation

Methodology Applied
Scientific EffectPrecipitation: Precipitation

Implementation Method 3

a pigment represented by the following chemical formula 1; a hydrosoluble solvent; and water. The pigment satisfies the following relation 1: 0.040 < Y/X ≤ 0.15, where X is peak intensity at a diffraction angle 2θ of from 26.5° to 27.5° and Y is peak intensity at a diffraction angle 2θ of from 11.0° to 11.5° in a CuKα X-ray diffraction spectrum

Methodology Applied
Scientific EffectCrystallization: Crystallisation

Implementation Method 4

a dispersing agent to enhance dispersion stability and inkjet printing performance

Methodology Applied
Scientific EffectDispersion: Dispersion (of waves)

Data Source

PatentEP2712899B1Ink composition, recording method, printed matter, ink cartridge, and inkjet recording device
Publication Date: 2017.09.06 RICOH CO LTD
  • EP2712899B1 patent drawingFigure 1
  • EP2712899B1 patent drawingFigure 2
  • EP2712899B1 patent drawingFigure 3~4

AI summary

An ink composition contains a pigment represented by the following chemical formula 1; a hydrosoluble solvent; and water, wherein the pigment satisfies the following relation 1: 0.040 &lt; Y/X &lt; 0.200 (Relation 1), where, in a CuKa X-ray diffraction spectrum having a wavelength of 1.541 Å, X represents a peak intensity at a Bragg (2θ ± 0.2 °) angle in a range of 2θ of from 26.5 ° to 27.5 ° and Y represents a peak intensity at a Bragg (2θ ± 0.2 °) angle in a range of 2θ of from 11.0 ° to 11.5 °: