Inkjet Ink Viscosity Control for High-Speed Jetting Stability

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Solution Overview

Problem

Inkjet printing systems face challenges with high-speed printing on lightweight recording media, where inkjet failures can occur due to meandering or flapping of the media, leading to image deterioration, and aqueous inks with high viscosities are difficult to print using conventional heads without compromising storage stability or dryability.

Innovation Solution

An image forming method using an ink composition with a water-soluble polymer of 1,000 or more molecular weight, a surfactant with HLB between 3 to 12, and a viscosity of 10 mPa·s to 14 mPa·s, allowing for high-frequency jetting of large droplets without deteriorating storage stability or dryability, and including polymer particles for enhanced stability and scratch resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the recording medium is conveyed at a high speed (30 m/min or higher), then productivity is improved, but the recording medium may meander or flap causing jetting failure

Engineering Contradiction:

Improveprinting speedVSAvoidjetting stability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent changes the physical parameters of the ink by adjusting viscosity to 10-14 mPa·s at 30°C and droplet volume to 60-120 pL, enabling stable jetting at high conveyance speeds without meandering or flapping issues

Inventive Principle:

Principle #35Parameter changes

2Reliability

If the distance between the recording medium and the head is increased to prevent contact, then jetting failure is reduced, but landing accuracy deteriorates

Engineering Contradiction:

Improvejetting stabilityVSAvoidlanding accuracy

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent optimizes droplet volume to 60-120 pL and viscosity to 10-14 mPa·s, allowing for improved landing accuracy even at larger head-to-medium distances required for high-speed conveyance

Inventive Principle:

Principle #35Parameter changes

3Reliability

If the droplet volume is increased to improve jetting stability, then a head capable of jetting large droplets is required, but nozzle diameter becomes large requiring high viscosity ink

Engineering Contradiction:

Improvecontinuous jettabilityVSAvoidnozzle requirements

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent optimizes the balance between viscosity (10-14 mPa·s) and droplet volume (60-120 pL), enabling use of conventional inkjet heads without requiring large nozzle diameters or excessively high viscosity inks

Inventive Principle:

Principle #35Parameter changes

4Productivity

If aqueous ink with high viscosity is used to enable high-speed printing, then productivity is improved, but storage stability and dryability are deteriorated

Engineering Contradiction:

Improveprinting speedVSAvoidstorage stability

Core Design Contradiction:

ProductivityVSStability of the object's composition

Solution Approach 1:

The patent optimizes viscosity to 10-14 mPa·s at 30°C, which is high enough for stable jetting at high speeds but low enough to maintain storage stability and dryability of the aqueous ink

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses a composite ink formulation containing water-soluble polymer, water-soluble organic solvent, and surfactant that work together to achieve the optimal viscosity range while maintaining storage stability and dryability

Inventive Principle:

Principle #40Composite materials

5Stability of the object's composition

If conventional aqueous ink with low viscosity is used, then storage stability is maintained, but high-speed printing capability is lost

Engineering Contradiction:

Improvestorage stabilityVSAvoidprinting speed

Core Design Contradiction:

Stability of the object's compositionVSProductivity

Solution Approach 1:

The patent increases viscosity from conventional low viscosity (several mPa·s) to an optimized range of 10-14 mPa·s, enabling high-speed printing capability while maintaining storage stability through controlled composition

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

Enables high-quality image formation at high speeds with high productivity, maintaining storage stability and dryability of the ink, and improving scratch resistance on non-absorbent or low-absorbent recording media.

Implementation Method 1

forming an image by jetting, onto a recording medium, an ink composition as liquid droplets each having a volume of from 60 pL to 120 pL, by using an inkjet head

Methodology Applied

Scientific EffectInkjet printing: Jet

Implementation Method 2

the ink composition having a viscosity at 30°C in a range of from 10 mPa·s to 14 mPa·s

Methodology Applied

Scientific EffectViscosity control:

Implementation Method 3

a surfactant having an HLB in a range of from 3 to 12 and a number average molecular weight of less than 1,000

Methodology Applied

Scientific EffectSurfactant action: Surfactant

Data Source

PatentEP3020566B1Image forming method and image recording material

Publication Date: 2017.03.22 FUJIFILM CORP

AI summary

Provided is an image forming method including forming an image by jetting, onto a recording medium, an ink composition as liquid droplets each having a volume of from 60 pL to 120 pL, by using an inkjet head, the ink composition incluings a water-soluble polymer having a number average molecular weight of 1,000 or more, a water-soluble organic solvent, and a surfactant having a HLB in a range of from 3 to 12 and a number average molecular weight of less than 1,000, and the ink composition having a viscosity at 30°C in a range of from 10 mPa·s to 14 mPa·s.