Ink Composition Host-Guest Complex Adaptive Surface Tension
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Solution Overview
Problem
Aqueous inkjet inks face challenges in maintaining optimal surface tension across different stages of the inkjetting process, as the addition of surface active agents alters surface tension uniformly, failing to adapt to the specific requirements of droplet jetting and spreading on a receiving medium.
Innovation Solution
An ink composition comprising a pigment, an aqueous vehicle, a host compound capable of forming a host-guest complex with a surface active agent, and a surface active agent with a first part affinity for the host compound and a second part with higher affinity for the hydrophobic receiving medium surface, allowing for adaptive surface tension adjustment based on the printing phase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a surface active agent is added to an ink composition, then the surface tension is reduced to improve droplet spreading on the receiving medium, but the surface tension cannot be optimized for different stages of the ink jetting process
Solution Approach 1:
The patent employs a dynamic surface tension adjustment mechanism using host-guest chemistry. The surface active agent is initially complexed with a host compound (such as cyclodextrin) to form a host-guest complex that remains in the ink composition without actively reducing surface tension. Upon contact with the receiving medium, the surface active agent dissociates from the host compound, dynamically switching from an inactive complexed state to an active free state, thereby reducing surface tension only when needed for droplet spreading.
Solution Approach 2:
The host compound acts as an intermediary that temporarily holds the surface active agent in an inactive form. The host-guest complex serves as a mediator between the surface active agent and the receiving medium, controlling the release timing. The host compound enables the surface active agent to be transported through the ink jetting system without premature activation, and then facilitates its release at the appropriate location (upon contact with the receiving medium).
2Area of stationary object
If the surface tension is reduced to improve droplet spreading, then the droplet coverage on the receiving medium is enhanced, but the jetting stability may be compromised
Solution Approach 1:
The patent applies preliminary action by pre-complexing the surface active agent with the host compound before the ink jetting process. This preliminary complexation prevents the surface active agent from reducing surface tension during ink storage and jetting, thereby maintaining jetting stability. The surface tension reduction action is postponed until after successful droplet ejection, when the complex dissociates upon contact with the receiving medium, ensuring both stable jetting and good spreading.
3Ease of operation
If a surface active agent is used to modify surface tension, then the ink composition can achieve better wettability on the receiving medium, but the surface tension remains constant throughout the ink jetting process
Solution Approach 1:
The patent implements parameter changes by transforming the surface tension from a constant value to a variable parameter that changes in response to environmental conditions. The surface tension remains high (stable parameter) during ink storage and jetting due to complexation, then changes to a low value (variable parameter) upon contact with the receiving medium due to dissociation. This dynamic parameter change enables both jetting stability and improved wettability.
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 composition achieves optimal surface tension for both droplet formation and spreading on the receiving medium, enhancing jetting stability and image homogeneity by dissociating the surface active agent to lower surface tension upon contact, thus improving droplet spreading and coverage.
Implementation Method 1
a host compound, which is soluble or dispersible in the aqueous vehicle and has a cavity capable of hosting a guest compound; a surface active agent, having a first part and a second part, wherein the first part has an affinity towards the cavity of the host compound and is capable of forming a host-guest complex with the host compound
Implementation Method 2
a surface active agent, having a first part and a second part, wherein the first part has an affinity towards the cavity of the host compound and is capable of forming a host-guest complex with the host compound and wherein the second part has a hydrophobic character and an affinity towards the hydrophobic surface of the receiving medium
Data Source
AI summary
The invention relates to an ink composition comprising a pigment, an aqueous vehicle, a host compound having a cavity and a surface active agent, wherein the surface active agent is capable of binding to the cavity of the host compound.The invention further relates to a method for preparing such ink compositions and to a method for applying an image onto a receiving medium using such ink composition.