Inkjet Ink for Polypropylene Substrates

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Solution Overview

Problem

Aqueous inks face challenges in forming images on non-polarized substrates like polypropylene (PP) due to poor wettability and abrasion resistance, leading to blurring and inadequate solid filling, especially when using silicone-based surfactants which provide excessive wettability but insufficient robustness.

Innovation Solution

The development of an ink comprising water, an organic solvent, a silicone-based surfactant, and a polyester-based urethane resin with a polyolefin portion, which balances wettability and film hardness, along with a specific ratio of silicone-based surfactant and organic solvent, such as 1,2-propane diol, to enhance image quality and abrasion resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If silicone-based surfactant is used to improve wettability on PP substrate, then image coverage is improved, but abrasion resistance deteriorates

Engineering Contradiction:

Improveimage coverageVSAvoidabrasion resistance

Core Design Contradiction:

Manufacturing precisionVSStrength

Solution Approach 1:

The patent changes the chemical composition parameters of the surfactant system by combining silicone-based surfactant (for wettability) with polyester-based urethane resin having polyolefin portion (for abrasion resistance). This parameter change resolves the contradiction by allowing both good image coverage and robust abrasion resistance to coexist in the ink formulation.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses a composite material approach by formulating ink with multiple resin components: polyester-based urethane resin having polyolefin portion (5-50 mass%) for abrasion resistance, and acrylic resin (10-60 mass%) for flexibility. This composite formulation allows the ink to simultaneously achieve good wettability on PP substrate and sufficient abrasion resistance.

Inventive Principle:

Principle #40Composite materials

2Object-affected harmful factors

If aqueous ink is used for printing on non-polarized substrate like polypropylene, then health safety is improved, but wettability deteriorates

Engineering Contradiction:

Improvehealth safetyVSAvoidwettability

Core Design Contradiction:

Object-affected harmful factorsVSManufacturing precision

Solution Approach 1:

The patent introduces polyester-based urethane resin having polyolefin portion as an intermediary substance that bridges the polar aqueous ink and non-polar polypropylene substrate. This resin component has affinity to both polar and non-polar environments, enabling effective wettability and adhesion on PP substrate while maintaining the safety benefits of aqueous-based formulation.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent modifies the chemical composition of the aqueous ink by adding specific resin components (polyester-based urethane resin with polyolefin portion and acrylic resin) that change the surface properties and wettability parameters, enabling the ink to effectively wet non-polarized PP substrate while remaining health-safe.

Inventive Principle:

Principle #35Parameter changes

3Strength

If ink forms strong film on plastic film surface, then abrasion resistance is improved, but flexibility of film deteriorates

Engineering Contradiction:

Improveabrasion resistanceVSAvoidfilm flexibility

Core Design Contradiction:

StrengthVSStability of the object's composition

Solution Approach 1:

The patent optimizes the molecular weight and composition parameters of the resin components. The polyester-based urethane resin having polyolefin portion (5-50 mass%) provides abrasion resistance, while the acrylic resin (10-60 mass%) with controlled glass transition temperature (30-110°C) and molecular weight (20,000-80,000) maintains film flexibility. This parameter optimization resolves the contradiction between strength and flexibility.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite film structure through the combination of polyester-based urethane resin and acrylic resin in specific ratios. This composite material system provides both abrasion resistance from the urethane resin and flexibility from the acrylic resin, resolving the contradiction between these two properties.

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 ink achieves improved wettability on PP and other substrates, resulting in high-quality images with enhanced robustness and abrasion resistance, particularly when a heating step is included after printing, improving the overall performance on non-porous media.

Implementation Method 1

a surfactant including a silicon-based surfactant

Methodology Applied

Scientific EffectSurface tension reduction: Surfactant

Implementation Method 2

an organic solvent

Methodology Applied

Scientific EffectEvaporation: Evaporation

Implementation Method 3

a resin including a polyester-based urethane resin having a polyolefin portion

Methodology Applied

Scientific EffectFilm formation:

Data Source

PatentUS10000067B2Ink, inkjet recording method, and inkjet recorded matter

Publication Date: 2018.06.19 RICOH CO LTD

AI summary

Ink includes water, an organic solvent, a surfactant including a silicon-based surfactant, and a resin including a polyester-based urethane resin having a polyolefin portion.