Titanium Dioxide Ink Dispersion Stability via Polymer Ratio
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Solution Overview
Problem
Existing aqueous dispersions and inkjet ink compositions with titanium dioxide particles face challenges in achieving stable dispersions and effective actinic light scattering for opaque images, as particles larger than 200 nm tend to settle and do not effectively scatter light when dried on a substrate.
Innovation Solution
The use of styrene-(meth)acrylic acid polymer, styrene-maleic anhydride polymer, or styrene-maleic acid polymer as dispersing agents, with a weight ratio of titanium dioxide to polymer ranging from 19:1 to 2:1, ensures that titanium dioxide particles are dispersed with a 95th percentile size of less than 200 nm and 50th percentile size of less than 130 nm, maintaining stability and enabling effective light scattering for opaque images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If titanium dioxide particles with size greater than 200 nm are used, then the dispersion is easier to prepare, but the particles settle and do not effectively scatter light for opaque images
Solution Approach 1:
The patent changes the particle size parameter of titanium dioxide to less than 200 nm (specifically 50-200 nm) to prevent settling and improve light scattering. This parameter change resolves the contradiction by selecting a size range that maintains both manufacturability and long-term stability in aqueous dispersion
Solution Approach 2:
The patent introduces a dispersant as an intermediary substance to facilitate the dispersion of titanium dioxide particles in aqueous medium. The dispersant acts as a mediator that enables stable dispersion of fine particles without requiring complex preparation procedures, thus resolving the contradiction between ease of manufacture and dispersion stability
2Ease of operation
If titanium dioxide particles with size greater than 200 nm are used, then the particles are easier to handle, but they do not effectively scatter actinic light for opaque images
Solution Approach 1:
The patent optimizes the particle size parameter to the 50-200 nm range, which is the critical threshold for effective light scattering. Particles in this size range provide sufficient scattering of actinic light for opaque image formation while remaining manageable in aqueous dispersion. This parameter optimization resolves the contradiction between ease of operation and light scattering effectiveness
3Ease of manufacture
If conventional dispersants are used with titanium dioxide particles, then the dispersion can be prepared, but the particles settle over time
Solution Approach 1:
The patent employs a specific dispersant as an intermediary that provides steric or electrosteric stabilization to prevent particle settling. The dispersant molecules adsorb onto particle surfaces and create repulsive forces that maintain stable suspension over time, resolving the contradiction between ease of dispersion formation and long-term compositional stability
Solution Approach 2:
The patent specifies particular parameters for the dispersant (concentration, molecular weight, hydrophilic-lipophilic balance) to optimize both dispersion formation and long-term stability. By carefully controlling these parameters, the system achieves both ease of manufacture and compositional stability without particle settling
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
This approach results in stable aqueous dispersions and inkjet ink compositions that produce opaque images with high refractive index, ensuring desired opacity and light scattering properties when dried on a substrate, enhancing the quality of inkjet printed images.
Implementation Method 1
the titanium dioxide particles are dispersed within the aqueous inkjet ink composition with a dispersing polymer that is a styrene-(meth)acrylic acid polymer, styrene-maleic anhydride polymer, or styrene-maleic acid polymer
Implementation Method 2
particles of titanium dioxide that are present in an amount of at least 4 weight % and up to and including 15 weight %, and the titanium dioxide particles have a 95th percentile particle size of less than 200 nm and a 50th percentile particle size of less than 130 nm... ensuring desired opacity and light scattering properties
Data Source
AI summary
A method of inkjet printing includes ink jetting an aqueous inkjet ink composition to form a white printed image on a substrate. The aqueous inkjet ink composition comprises particles of titanium dioxide that are present in an amount of at least 4 to 15 weight % and the particles have a 95th percentile particle size of less than 200 nm and a 50th percentile particle size of less than 130 nm. The titanium dioxide particles are dispersed within the aqueous inkjet ink composition using a dispersing polymer that is a styrene-(meth)acrylic acid polymer, styrene-maleic anhydride polymer, or styrene-maleic acid polymer and the weight ratio of the titanium dioxide particles to the dispersing polymer is from 19:1 to and including 2:1.