Latex Particulates for Inkjet Inks with Intermingled Polymer Strands

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Solution Overview

Problem

Aqueous inkjet inks face challenges with latex particulates regarding stability and durability under thermal shear conditions and storage, particularly when used on nonporous media, leading to nozzle reliability issues and instability over time.

Innovation Solution

Incorporating intermingled low Tg and high Tg polymer strands in latex particulates, synthesized using vinyl monomers, to mimic polyurethane properties, providing superior scratch resistance and stability without using polyurethane materials, while matching refractive indices for improved gloss and haze.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If latex particulates are incorporated into aqueous inkjet inks to improve durability and scratch resistance, then the durability and abrasion resistance of prints are improved, but the ink stability during storage and nozzle reliability under thermal shear conditions deteriorate

Engineering Contradiction:
Improvescratch resistanceVSAvoidnozzle reliability
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The patent modifies the chemical composition parameters of the latex particulates by incorporating specific functional groups (carboxyl, hydroxyl, amine) and controlling molecular weight and glass transition temperature. These parameter changes enable the latex to maintain stability during storage while providing adequate scratch resistance, resolving the contradiction between durability improvement and nozzle reliability.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent creates composite latex particulates that combine multiple polymer components with different functional groups and properties. This composite structure allows the latex to exhibit both stability during storage and durability after printing, effectively resolving the contradiction between scratch resistance and nozzle reliability by integrating complementary material properties.

Inventive Principle:
Principle #40Composite materials

2Duration of action of stationary object

If latex particulates are used to enhance durability on nonporous media, then outdoor weatherability and water resistance are improved, but the ink stability over time deteriorates due to settling

Engineering Contradiction:
Improveoutdoor weatherabilityVSAvoidink stability
Core Design Contradiction:
Duration of action of stationary objectVSStability of the object's composition

Solution Approach 1:

The patent optimizes the molecular weight and glass transition temperature parameters of the latex particulates to achieve a balance between stability and performance. By controlling these parameters within specific ranges, the latex remains stably dispersed in the ink during storage while forming durable films on nonporous media for long-term outdoor weatherability.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent introduces surface functional groups (carboxyl, hydroxyl, amine) on the latex particulates that provide localized interaction with the ink vehicle and substrate. This local quality enhancement improves both the stability of the latex in the ink formulation and the adhesion/durability on the printed surface, resolving the contradiction between weatherability and storage stability.

Inventive Principle:
Principle #3Local quality

3Strength

If polyurethane dispersions are used to provide scratch resistance, then abrasion resistance is improved, but wet durability and solvent resistance deteriorate

Engineering Contradiction:
Improvescratch resistanceVSAvoidsolvent resistance
Core Design Contradiction:
StrengthVSObject-affected harmful factors

Solution Approach 1:

The patent develops composite latex particulates that combine multiple polymer components with different functional groups. This composite structure provides scratch resistance similar to polyurethane while the specific functional group composition (carboxyl, hydroxyl, amine) enhances solvent and water resistance, effectively resolving the contradiction between abrasion resistance and solvent resistance.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent modifies the chemical composition parameters of the latex by incorporating specific functional groups and controlling the ratio of hard and soft segments. These parameter changes enable the latex to achieve both scratch resistance and improved solvent/wet durability, overcoming the limitations of conventional polyurethane dispersions.

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 resulting latex particulates enhance the durability and stability of inkjet inks, improving scratch resistance and outdoor weatherability, and maintaining performance across various substrates and printing architectures.

Implementation Method 1

When printed as part of an inkjet ink, a latex component of the ink can form a film on a media surface, entrapping and protecting the colorant within the hydrophobic print film

Methodology Applied
Scientific EffectFilm formation:

Implementation Method 2

latex particulate compositions and associated methods described herein can include intermingled low Tg polymer strands and high Tg polymer strands providing for a unique latex structure

Methodology Applied
Scientific EffectGlass transition temperature differential:

Implementation Method 3

the refractive index of the low Tg polymer strand can be within 1% of the refractive index of the high Tg polymer strand

Methodology Applied
Scientific EffectRefractive index matching: Refraction

Data Source

PatentEP2895532B1Latexes and associated inkjet inks
Publication Date: 2020.07.01 HEWLETT PACKARD DEVELOPMENT COMPANY LP

AI summary

The present disclosure provides latexes and related methods and inkjet inks incorporating such latexes. A latex particulate can comprising multiple intermingled discrete polymer strands, including a low Tg polymer strand having a Tg below 50°C and a high Tg polymer strand having a Tg at 50°C or above. The Tg of the high Tg polymer strand can be at least 50°C greater than the Tg of the low Tg polymer strand, and the average refractive index of the monomers of the low Tg polymer strand can be within 1% of the average refractive index of the monomers of the high Tg polymer strand.