Ink Formulation for Plain Paper Inkjet Recording

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Inkjet recording on plain paper faces issues such as feathering, bleeding, reduced image density, color forming property, water resistance, light resistance, gas resistance, and fixing property due to inferior ink absorbability, which existing inks fail to adequately address without compromising image quality or increasing complexity and energy consumption.

Innovation Solution

An ink formulation with a solid content of 10% to 30% comprising a water-dispersible resin and a pigment, optimized surfactants, and polyhydric alcohols like glycerin to enhance permeability, drying speed, and reliability, ensuring high image quality and stability without nozzle clogging.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If aqueous ink is used for inkjet recording on plain paper, then the apparatus is simple and energy-saving, but the image quality deteriorates due to feathering, bleeding, and reduced density

Engineering Contradiction:
Improveapparatus simplicityVSAvoidimage quality
Core Design Contradiction:
Device complexityVSManufacturing precision

Solution Approach 1:

The patent changes the chemical parameters of the ink by introducing a specific water-dispersible resin system with controlled molecular weight (5,000-50,000) and functional groups. This resin modification allows the ink to achieve both good image quality on plain paper and maintain apparatus simplicity without requiring complex heating or drying systems

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite ink formulation combining water-dispersible resin, pigment, and specific additives. This composite material approach enables the ink to simultaneously provide good dispersion stability, high image density, and fast drying on plain paper, resolving the contradiction between simplicity and image quality

Inventive Principle:
Principle #40Composite materials

2Reliability

If pigment is used as coloring agent to improve water resistance and light resistance, then durability is enhanced, but density and color forming property are reduced

Engineering Contradiction:
Improvewater resistance and light resistanceVSAvoidimage density
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The patent optimizes the particle size parameter of the pigment to 0.01-1.0 μm and controls the resin-to-pigment ratio at 1:9 to 9:1. These parameter changes enable pigment-based ink to achieve both high durability and high image density, overcoming the traditional trade-off between pigment durability and dye density

Inventive Principle:
Principle #35Parameter changes

3Manufacturing precision

If solid content is increased to improve image density and color forming property, then image quality is enhanced, but viscosity increases causing nozzle clogging

Engineering Contradiction:
Improveimage densityVSAvoidjet stability
Core Design Contradiction:
Manufacturing precisionVSStability of the object's composition

Solution Approach 1:

The patent carefully controls the solid content parameter within 1-20% and optimizes the resin molecular weight to 5,000-50,000. These parameter changes ensure the ink maintains low viscosity for reliable jetting while achieving high image density through optimized solid content composition

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent uses local quality by creating a water-dispersible resin with specific functional groups distributed throughout the ink formulation. This localized functional distribution improves pigment dispersion and maintains low viscosity even at higher solid contents, preventing nozzle clogging while enhancing image density

Inventive Principle:
Principle #3Local quality

4Speed

If permeability is enhanced to reduce bleeding and improve drying speed, then fixation is improved, but feathering and show through increase

Engineering Contradiction:
Improvedrying speedVSAvoidfeathering control
Core Design Contradiction:
SpeedVSManufacturing precision

Solution Approach 1:

The patent optimizes the surface tension parameter of the ink by selecting specific surfactants and controlling the resin structure. This parameter adjustment enables the ink to achieve fast drying speed through enhanced permeability while simultaneously reducing feathering and show through effects

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 achieves high image density, improved color forming properties, and reliable jetting performance on plain paper with enhanced drying speed and resistance, comparable to electrophotographic systems, while maintaining low viscosity and surface tension for efficient inkjet operation.

Implementation Method 1

hydrophilicity is imparted to the pigment surface by surface modification such as oxidation, sulfonation or graft polymerization

Methodology Applied
Scientific EffectSurface modification:

Implementation Method 2

dispersibility has been improved and particle diameters have been minimized

Methodology Applied
Scientific EffectDispersion: Dispersion (of waves)

Implementation Method 3

enhance permeability

Methodology Applied
Scientific EffectPermeation: Permeation

Implementation Method 4

control the permeability of the ink into the paper

Methodology Applied
Scientific EffectCapillary action: Capillary Action

Implementation Method 5

a surface tension of the ink is 35 mN/m or less

Methodology Applied
Scientific EffectSurface tension reduction: Surface Tension

Implementation Method 6

wetting agents such as glycerin

Methodology Applied
Scientific EffectWetting: Wetting

Implementation Method 7

a viscosity of the ink is 5 mPa·s to 20 mPa·s at 25°C

Methodology Applied
Scientific EffectViscosity control:

Implementation Method 8

enhanced drying speed

Methodology Applied
Scientific EffectEvaporation: Evaporation

Data Source

PatentEP1926785B1Ink for recording, and ink cartridge, ink recorded matter, inkjet recording apparatus and inkjet recording method using the same
Publication Date: 2016.05.04 RICOH CO LTD
  • EP1926785B1 patent drawingFigure 1
  • EP1926785B1 patent drawingFigure 2
  • EP1926785B1 patent drawingFigure 3

AI summary

There is provided an ink for recording, which contains: a coloring agent; a water-dispersible resin; a wetting agent; a surfactant; and water, wherein a total solid content of the coloring agent and the water-dispersible resin is 10% by mass to 30% with respect to a total mass of the ink, a ratio B/C is 0.1 to 1.6 where B is a solid content of the coloring agent in the ink, and C is a solid content of the water-dispersible resin in the ink, a viscosity of the ink is 5 mPa·s to 20 mPa·s at 25°C, and a surface tension of the ink is 35 mN/m or less.