Inkjet Ink Surfactant Systems for Optical Density Control
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Solution Overview
Problem
Inkjet printing faces challenges in achieving high optical density (O.D.) across various paper types due to competing effects of ink penetration and spreading, which are influenced by surfactant and solvent interactions, leading to suboptimal printing performance.
Innovation Solution
The development of inkjet ink compositions incorporating specific surfactant systems, including alkoxylated alkyne-containing alkylene diols and acetylene alcohols or alkoxylated phosphate esters, which minimize ink penetration and enhance spreading, thereby optimizing dot density and optical density on different paper types.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If conventional surfactants with high solubility are used, then ink composition stability is improved, but optical density is reduced due to excessive ink penetration
Solution Approach 1:
The patent changes the solubility parameter of the surfactant from high solubility to limited solubility (less than 0.5% in 5% glycerol/water mixture). This parameter change allows the surfactant to remain stable in the ink composition while preventing excessive ink penetration into the paper, thereby improving optical density without sacrificing composition stability.
2Illumination intensity
If ink penetration is increased to improve dot density, then optical density is improved, but ink spreading is reduced leading to poor print quality
Solution Approach 1:
The patent introduces a limited solubility surfactant as an intermediary substance that mediates between ink penetration and spreading requirements. This surfactant selectively interacts with the ink composition to control penetration into the paper while maintaining adequate spreading, thus resolving the contradiction between these two competing requirements.
3Ease of operation
If surfactant concentration is increased to improve spreading, then dot density is improved, but agglomeration occurs reducing print quality
Solution Approach 1:
The patent changes the solubility parameter of the surfactant to limited solubility (less than 0.5% in 5% glycerol/water mixture). This parameter change ensures that even at the concentrations needed for effective spreading, the surfactant does not dissolve completely, thereby preventing agglomeration and maintaining composition stability while achieving adequate ink spreading.
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 surfactant systems improve optical density by controlling ink penetration and spreading, resulting in higher dot density and better print quality on both uncoated and coated papers, while maintaining stability and preventing agglomeration.
Implementation Method 1
The surfactant systems improve optical density by controlling ink penetration and spreading
Implementation Method 2
Surfactants in inkjet inks are used to modify surface tension, which can facilitate one or more of ink transport in a print head, drop ejection from a firing chamber, and drop spreading and penetration on substrates
Data Source
AI summary
Disclosed herein are ink compositions comprising a self-dispersed pigment in a liquid vehicle. The liquid vehicle can comprise a solvent/water mixture in which the composition further comprises a surfactant system having limited solubility/compatibility with the liquid vehicle. Also disclosed are surfactant systems comprising at least a first and a second surfactant, where the first surfactant is selected from alkoxylated alkyne-containing alkylene diols and N-alkyl pyrrolidones, and wherein the first surfactant has a solubility of less than 0.5% in a 5% glycerol/water mixture, and where the a second surfactant is selected from acetylene alcohols comprising linear or branched C1-C14 alkyls, and alkoxylated phosphate esters.