Ink Formulation Extends Printhead Lifetime

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Solution Overview

Problem

High-speed pagewidth inkjet printers, particularly those with Memjet® printheads, face challenges in printhead lifetime due to aggressive inks, especially dye-based inks that corrode heater elements, leading to reduced print quality and shorter printhead lifespan, with existing solutions involving potentially harmful solvents like ethylene glycol and sulfolane.

Innovation Solution

An inkjet ink formulation comprising a disazo dye, 1,3-propanediol, a high-order glycol such as triethylene glycol, and water, without harmful co-solvents like ethylene glycol and sulfolane, which improves printhead lifetime while maintaining low toxicity and enhancing rehydration and anti-curl properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If uncoated heater elements are used in Memjet printheads, then heat transfer efficiency and self-cooling characteristics are improved, but printhead lifetime is reduced due to corrosion from aggressive inks

Engineering Contradiction:

Improveheat transfer efficiencyVSAvoidprinthead lifetime

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent changes the chemical composition parameters of the ink formulation by selecting specific dye structures (with electron-withdrawing groups at positions 2 and 6 of the central arylene ring) and co-solvent ratios (ethylene glycol 10-30 wt%, sulfolane 5-20 wt%) to reduce the ink's aggressiveness toward heater elements, thereby extending printhead lifetime while maintaining thermal efficiency

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite ink formulation combining specific disazo dye structures with a tailored co-solvent system (ethylene glycol and sulfolane in specific ratios) to achieve synergistic effects that reduce corrosion while maintaining printing performance

Inventive Principle:

Principle #40Composite materials

2Reliability

If protective coatings are applied to heater elements, then printhead lifetime is improved, but heat transfer efficiency and self-cooling characteristics are reduced

Engineering Contradiction:

Improveprinthead lifetimeVSAvoidheat transfer efficiency

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent converts the harmful corrosiveness of the ink into a beneficial property by formulating the ink to specifically avoid corroding uncoated heater elements, through careful selection of dye chemistry and co-solvent composition, thereby eliminating the need for protective coatings while maintaining longevity

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Adaptability or versatility

If black dye-based inks are used in multi-color printheads, then printing capability is provided, but printhead lifetime is limited due to high corrosiveness of black dyes

Engineering Contradiction:

Improveprinting capabilityVSAvoidprinthead lifetime

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent modifies the chemical parameters of black dye-based inks by specifying particular disazo dye structures with electron-withdrawing substituents and optimizing co-solvent composition to dramatically reduce corrosion while preserving black ink's essential printing functions

Inventive Principle:

Principle #35Parameter changes

4Reliability

If ethylene glycol and sulfolane are used as co-solvents, then printhead lifetime is improved, but ink toxicity increases

Engineering Contradiction:

Improveprinthead lifetimeVSAvoidink toxicity

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent optimizes the concentration parameters of ethylene glycol (10-30 wt%) and sulfolane (5-20 wt%) within safe ranges that provide maximum corrosion protection while minimizing toxicity, and balances these with water content to achieve low overall toxicity

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 formulation significantly extends printhead lifetime, achieving over 380 million ejections with improved lightfastness and rehydration characteristics, and meets safety standards by avoiding harmful solvents, making it suitable for a wide range of applications.

Implementation Method 1

a disazo dye of formula (I)

Methodology Applied

Scientific EffectLight absorption: Absorption (EM radiation)

Implementation Method 2

thermal bubble-forming printheads

Methodology Applied

Scientific EffectThermal bubble formation: Bubble

Implementation Method 3

thermal bubble-forming printheads

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 4

resistive heater elements

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Implementation Method 5

self-cooling characteristics

Methodology Applied

Scientific EffectHeat transfer: Conduction (thermal)

Data Source

PatentEP3583173B1Low toxicity ink formulations with improved printhead lifetime

Publication Date: 2020.11.04 MEMJET TECH LTD

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AI summary

An Inkjet ink includes; (i) a disazo dye of formula (1); (ii) 1,3-propanediol; (iii) a glycol compound selected from the group consisting of: triethylene glycol and tetraethylene glycol; and (iv) water. The ink has low toxicity and is preferably absent ethylene glycol and sulfolane.