Water-based pigment inks

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Solution Overview

Problem

Existing water-based inks for inkjet printing on non-porous substrates, such as BOPP and PET, lack good jetting performance, printed image quality, ink storage stability, long open time, resolubility, and robust film-forming properties without the need for chemical primers or pre-treatments.

Innovation Solution

A water-based ink formulation using a poly(styrene-maleic acid) co-polymer or poly(styrene-maleamic acid) co-polymer as a dispersant, surfactant, and binder, which does not require additional polymers, allowing direct printing on non-chemically treated substrates with excellent adhesion, resolubility, and film-forming properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If water-based inks are formulated for inkjet printing on non-porous substrates, then adhesion and film-forming properties are improved, but jetting performance and storage stability deteriorate

Engineering Contradiction:
ImproveadhesionVSAvoidjetting performance
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The patent changes the chemical parameters of the ink formulation by using poly(styrene-maleic acid) co-polymer with specific acid number (≥255 mg KOH/g) and molecular weight (3,000-20,000 Daltons), and controlling pigment concentration (0.1-10%) and polymer solids content (0.1-5%), to achieve both good jetting performance and adhesion on non-porous substrates without chemical pre-treatment

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent uses a composite ink formulation combining poly(styrene-maleic acid) co-polymer with specific pigments and water-based vehicle, where the co-polymer serves multiple functions as dispersant, surfactant, and binder, creating a composite material that resolves the contradiction between jetting performance and adhesion

Inventive Principle:
Principle #40Composite materials

2Strength

If chemical primers or pre-treatments are applied to substrates, then adhesion is improved, but process complexity and manufacturing cost increase

Engineering Contradiction:
ImproveadhesionVSAvoidprocess complexity
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The patent extracts and eliminates the need for chemical primer layers or substrate pre-treatments by incorporating adhesion-promoting functionality directly into the ink formulation through the poly(styrene-maleic acid) co-polymer, thereby simplifying the overall printing process while maintaining good adhesion on non-porous substrates

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The ink formulation performs self-service by containing all necessary adhesion-promoting properties within the poly(styrene-maleic acid) co-polymer, allowing the ink to adhere directly to non-porous substrates without requiring external chemical primers or pre-treatment processes

Inventive Principle:
Principle #25Self-service

3Stability of the object's composition

If multiple polymers are used in ink formulation, then film-forming properties are improved, but ink complexity and manufacturing cost increase

Engineering Contradiction:
Improvefilm-forming propertiesVSAvoidink complexity
Core Design Contradiction:
Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The patent applies the multi-functionality principle by designing the poly(styrene-maleic acid) co-polymer to simultaneously serve as dispersant, surfactant, and binder in the ink formulation, thereby achieving robust film-forming properties while minimizing ink complexity and eliminating the need for multiple separate polymer additives

Inventive Principle:
Principle #6Universality (Multi-functionality)

4Duration of action of stationary object

If ink formulations are optimized for storage stability, then shelf life is improved, but jetting performance and open time deteriorate

Engineering Contradiction:
Improvestorage stabilityVSAvoidopen time
Core Design Contradiction:
Duration of action of stationary objectVSDuration of action of moving object

Solution Approach 1:

The patent optimizes the balance between storage stability and open time by carefully controlling the acid number (≥255 mg KOH/g) and molecular weight (3,000-20,000 Daltons) of the poly(styrene-maleic acid) co-polymer, and adjusting pigment to polymer solids ratio, thereby achieving both long shelf life and extended open time with good jetting performance

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 exhibits good adhesion, resolubility, and film-forming properties on non-porous substrates without chemical pre-treatment, ensuring reliable printing with vibrant colors and durability through adhesion, scratch resistance, and resistance to water and alcohol, suitable for industrial applications.

Implementation Method 1

a polymeric dispersant based on a poly(styrene-maleic acid) co-polymer and/or a poly(styrene-maleamic acid) co-polymer

Methodology Applied
Scientific EffectDispersion: Dispersion (of waves)

Implementation Method 2

a polymeric dispersant based on a poly(styrene-maleic acid) co-polymer and/or a poly(styrene-maleamic acid) co-polymer

Methodology Applied
Scientific EffectSurfactant: Surfactant

Implementation Method 3

The ink exhibits good adhesion, resolubility, and film-forming properties on non-porous substrates without chemical pre-treatment

Methodology Applied
Scientific EffectAdhesion: Adhesive

Data Source

PatentEP4153691B1Water-based pigment inks
Publication Date: 2026.01.28 SUN CHEMICAL BV

AI summary

The present invention relates to a printing ink composition comprising a polymer selected from a poly(styrene-maleic acid) co-polymer having an acid number of ≥ 225 mg KOH/g, a poly(styrene-maleamic acid) co-polymer having an acid number of ≥ 225 mg KOH/g or a combination thereof, wherein the co-polymer is a lithium, sodium, potassium, ammonium or quaternary ammonium salt or combinations thereof. The printing ink composition is suitable for directly printing onto non-porous substrates particularly without the need for a chemical primer layer or chemical pre-treatment.