Amphoteric Polymer Liquid Dispersant for Ink Jet Bleeding Control

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Solution Overview

Problem

Ink jet recording methods face challenges with bleeding and lack of sharpness at color boundaries due to ink agglomeration and penetration issues, leading to unsatisfactory abrasion resistance and preservability of recorded materials.

Innovation Solution

An ink jet recording method using a liquid dispersant with an amphoteric polymer having a core portion with an anion group and a shell portion with a cation group, dispersed in a medium, which enhances the fixing property of the anionic ink by electrostatic attraction, reducing bleeding and improving image quality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-generated harmful factors

If an acidic water-soluble resin is used for the processing liquid to prevent bleeding at color boundaries, then bleeding is reduced, but the recording medium undergoes modification with prolonged preservation, degrading preservability

Engineering Contradiction:
Improvebleeding at color boundariesVSAvoidpreservability of recorded material
Core Design Contradiction:
Object-generated harmful factorsVSReliability

Solution Approach 1:

The invention changes the pH parameter of the processing liquid from acidic (pH < 7) to neutral or slightly basic (pH 7-8.5), eliminating the harmful effect of acidic modification on the recording medium while maintaining effective ink fixation and bleeding prevention through the amphoteric polymer's unique charge properties

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention uses an amphoteric polymer that contains both cationic and anionic groups within the same molecule, creating a composite functional material that can simultaneously interact with both acidic and basic components of the ink, providing effective fixation without the harmful effects of purely acidic resins

Inventive Principle:
Principle #40Composite materials

2Strength

If a polyvalent metal-containing reaction liquid is used to destabilize coloring material and improve adhesion, then abrasion resistance improves, but the liquid must be acidic to stabilize metal ions, causing recording medium modification and reduced preservability

Engineering Contradiction:
Improveabrasion resistanceVSAvoidpreservability of recorded material
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The invention extracts and eliminates the polyvalent metal component from the processing liquid, relying instead on the amphoteric polymer's intrinsic ability to interact with coloring materials through its dual charge groups, thereby avoiding the need for acidic conditions and the associated harmful effects on the recording medium

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The amphoteric polymer acts as an intermediary substance that mediates between the ink and recording medium, providing the necessary adhesion and fixation functions without requiring acidic conditions or metal ions, thus preventing recording medium modification

Inventive Principle:
Principle #24Intermediary (Mediator)

3Object-generated harmful factors

If an amphoteric ionic polymer compound is used to increase viscosity and prevent bleeding by making pH difference larger than isoelectric point, then bleeding is reduced, but fixing of coloring material is not considered, resulting in poor adhesiveness and marker resistance

Engineering Contradiction:
ImprovebleedingVSAvoidadhesiveness and marker resistance
Core Design Contradiction:
Object-generated harmful factorsVSStrength

Solution Approach 1:

The invention creates local quality differentiation within the amphoteric polymer structure by having a core portion with anionic groups and a shell portion with cationic groups, allowing different regions of the same molecule to perform different functions: the core provides structural stability while the shell provides active interaction sites for ink fixation

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The core-shell amphoteric polymer structure combines the benefits of both anionic and cationic polymers in a single integrated material, enabling simultaneous prevention of bleeding through viscosity control and effective ink fixation through dual charge interactions, thereby achieving both bleeding prevention and good adhesiveness

Inventive Principle:
Principle #40Composite materials

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 method achieves high-definition images with reduced bleeding, excellent abrasion resistance, and improved preservability by forming firm agglomerates of the coloring material on the recording medium, enhancing the overall quality of the recorded materials.

Implementation Method 1

The liquid dispersant contains an amphoteric polymer having a core portion with an anion group and a shell portion with a cation group... enhances the fixing property of the anionic ink by electrostatic attraction

Methodology Applied
Scientific EffectElectrostatic attraction: Electrostatics

Data Source

PatentUS8752947B2Ink jet recording method and liquid dispersant
Publication Date: 2014.06.17 RICOH CO LTD

AI summary

An ink jet recording method including attaching a liquid dispersant in which an amphoteric polymer containing a core portion having an anion group and a shell portion having a cation group that covers the core portion is dispersed in a dispersing medium to a recording medium and discharging and attaching anionic ink containing a coloring material and water to the surface of the recording medium to which the liquid dispersant is attached.