Pre-treatment Liquid for Coated Paper Image Quality

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Solution Overview

Problem

Conventional image forming methods using pre-treatment liquids on coated papers face issues with image granularity and glossiness deterioration due to the interaction between the pre-treatment liquid and the recording medium, leading to cohesion ability loss and contamination problems.

Innovation Solution

A pre-treatment liquid comprising a water-soluble cationic polymer, a surface conditioner with a polyether-modified polydimethylsiloxane structure, and an acetylene glycol surfactant, which improves ink penetration, cohesion, and gloss retention when applied to coated papers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a pre-treatment liquid is applied to a recording medium having a coating layer to prevent image bleeding, then image quality is improved, but the pre-treatment liquid contacts transfer members and causes contamination, damages transfer members, and deteriorates image quality through retransfer

Engineering Contradiction:

Improveimage qualityVSAvoidcontamination and damage to transfer members

Core Design Contradiction:

Manufacturing precisionVSObject-generated harmful factors

Solution Approach 1:

The pre-treatment liquid is applied to the recording medium in advance to modify the coating layer surface properties before inkjet printing, creating optimal conditions for ink absorption and preventing bleeding. This preliminary modification ensures that the ink penetrates properly without causing contamination to transfer members during subsequent handling.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The invention modifies the chemical and physical parameters of the coating layer through the pre-treatment liquid, changing its surface energy, porosity, and hydrophilicity to optimize ink reception. These parameter changes enable the coating layer to absorb ink effectively without requiring excessive pre-treatment liquid that would cause contamination.

Inventive Principle:

Principle #35Parameter changes

2Object-generated harmful factors

If the pre-treatment liquid is dried after application to prevent transfer, then transfer problems are solved, but cohesion ability of the pre-treatment liquid deteriorates and image glossiness is reduced

Engineering Contradiction:

Improvetransfer of pre-treatment liquidVSAvoidimage glossiness and cohesion

Core Design Contradiction:

Object-generated harmful factorsVSManufacturing precision

Solution Approach 1:

The pre-treatment liquid is designed as a single-use, disposable treatment that is applied, allowed to dry, and then serves its function without needing to maintain cohesion. Once dried, it forms a stable modified layer that prevents transfer while maintaining image quality, eliminating the need for continuous cohesion.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The invention changes the physical state of the pre-treatment liquid from liquid to dried film, fundamentally altering its properties. In liquid form, it modifies the coating layer; in dried form, it provides a stable, non-transferring surface that maintains glossiness and cohesion for image formation.

Inventive Principle:

Principle #35Parameter changes

3Speed

If aqueous ink is used on a recording medium without a coating layer, then penetration is improved, but droplets merge on the surface causing color changes and bleeding

Engineering Contradiction:

Improveink penetrationVSAvoidimage quality and color accuracy

Core Design Contradiction:

SpeedVSManufacturing precision

Solution Approach 1:

The pre-treatment liquid creates local quality differences within the coating layer, generating zones with different absorption capacities. This localized modification ensures that ink penetrates at optimal rates in different areas, preventing both excessive penetration that causes bleeding and insufficient penetration that causes droplet merging.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The invention changes the physical and chemical parameters of the coating layer through pre-treatment, modifying its porosity, surface energy, and hydrophilicity. These parameter changes enable the coating layer to control ink penetration speed and distribution, achieving optimal balance between penetration and prevention of droplet merging.

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 solution effectively prevents deterioration of image granularity and glossiness on coated papers by enhancing ink penetration and cohesion, while minimizing contamination and transfer issues during the drying process.

Implementation Method 1

a flocculant formed of a water-soluble cationic polymer obtained by copolymerizing an amine monomer and an epihalohydrin monomer

Methodology Applied

Scientific EffectFlocculation: Flocculation

Implementation Method 2

the surface conditioner is a compound having a polyether-modified polydimethylsiloxane structure

Methodology Applied

Scientific EffectSurface tension reduction: Surfactant

Implementation Method 3

the surfactant is an acetylene glycol surfactant

Methodology Applied

Scientific EffectSurfactant action: Surfactant

Implementation Method 4

the pre-treatment liquid is dried after applied

Methodology Applied

Scientific EffectEvaporation: Evaporation

Data Source

PatentEP2774771B1Pre-treatment liquid and image forming method

Publication Date: 2019.09.04 RICOH CO LTD

Figure 1

AI summary

A pre-treatment liquid includes a flocculant formed of a water-soluble cationic polymer obtained by copolymerizing an amine monomer and an epihalohydrin monomer; a surface conditioner; a surfactant; a water-soluble organic solvent; and water.