Core-Shell Latex Particles for Ink-Jet Durability
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Solution Overview
Problem
Ink-jet inks using dyes lack durability due to low water, smear, and light fastness, while replacing dyes with pigments improves durability but can lead to increased viscosity and clogging issues with latex additives.
Innovation Solution
Development of latex particles with a polymer core and a urethane polymer shell, where the shell has a glass transition temperature at least 10°C higher than the core, to enhance durability without compromising print reliability, achieved by forming a monomer emulsion, polymerizing core and shell monomers, and incorporating urethane acrylate monomers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dyes are used as colorants in thermal ink-jet inks, then vibrant colors and low cost are achieved, but image durability (water fastness, smear fastness, and light fastness) is poor
Solution Approach 1:
The patent introduces latex particles as an intermediary substance that binds pigment particles together and to the substrate. This mediator allows the use of pigments (which provide durability) while the latex matrix ensures good adhesion and smear resistance, resolving the contradiction between durability and ease of manufacture.
Solution Approach 2:
The invention creates a composite material system consisting of pigment particles dispersed in a latex matrix. This composite approach combines the advantages of pigments (durability, light fastness) with the advantages of latex (adhesion, smear resistance), achieving both image durability and manufacturing feasibility.
2Reliability
If pigments are used as colorants instead of dyes, then image durability is improved, but smear fastness may be lessened due to surface properties
Solution Approach 1:
The patent uses latex particles forming a flexible film matrix that encapsulates pigment particles. This thin film structure protects the pigment surface from smearing while maintaining the durability benefits of pigments, effectively resolving the smear fastness issue.
Solution Approach 2:
The latex acts as an intermediary between the pigment particles and the external environment, providing a protective layer that prevents direct contact and smearing of pigment particles, thereby improving smear fastness while maintaining durability.
3Reliability
If latexes are added to ink-jet inks to improve image durability, then durability is enhanced, but viscosity increases leading to clogging and misdirected print drops
Solution Approach 1:
The patent modifies the parameters of the latex particles, specifically controlling their size distribution and glass transition temperature. By optimizing these parameters, the latex provides maximum durability enhancement at minimum concentration, reducing viscosity impact while maintaining reliability benefits.
Solution Approach 2:
The invention creates latex particles with specific local properties - a core-shell structure where the shell has different characteristics than the core. This local quality differentiation allows the particles to provide durability where needed while maintaining overall ink flow properties.
4Reliability
If high concentrations of latex are used to ensure print reliability, then durability is improved, but viscosity increases causing clogging issues
Solution Approach 1:
The patent changes key parameters of the latex particles including size (50-500 nm range) and glass transition temperature (at least 10°C higher in shell than core). These parameter optimizations allow high print reliability at low concentrations, preventing clogging while maintaining durability.
Solution Approach 2:
The core-shell structure essentially creates an optimized version of traditional latex particles, with the shell acting as a protective copy that enhances performance while reducing the overall amount of material needed, thereby preventing clogging.
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 latex particles improve image durability and shear stability, reducing the need for high latex concentrations by up to 75% while maintaining print reliability and film-forming properties.
Implementation Method 1
polymerizing core and shell monomers to form a core-shell latex particle
Implementation Method 2
the latex particles improve image durability and shear stability, reducing the need for high latex concentrations by up to 75% while maintaining print reliability and film-forming properties
Data Source
AI summary
A latex particle for use in ink-jet inks can comprise a latex polymer core and a latex polymer shell such that the latex polymer shell has a Tg that is at least 10° C. greater than the Tg of the latex polymer core. The latex polymer core can comprise at least one polymerized core monomer. The latex polymer shell can comprise at least two polymerized shell monomers including a urethane acrylate monomer.