Ink-Jet Ink Formulation for Stable Ejection and Image Quality
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Solution Overview
Problem
Pigment inks used in ink-jet recording apparatuses tend to thicken and solidify, leading to ejection failure and image defects due to drying, and the addition of penetrating agents can cause colors to become lighter or transparent, affecting image quality.
Innovation Solution
The use of a water-based ink containing a pigment dispersion, a super-penetrating agent with specific solubility parameters, and a high SP organic solvent, such as 1,3-propanediol, to improve ink penetration and stability, preventing color lightening and maintaining image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If pigment ink is used to improve light resistance and water resistance, then image toughness is improved, but ink ejection fails when the ink has not been ejected for a while due to thickening and solidification
Solution Approach 1:
The patent changes the chemical parameters of the ink by introducing a hydrophilic group onto the pigment surface, modifying the pigment's properties to enable stable dispersion in aqueous medium without requiring dispersants that would compromise ejection reliability
Solution Approach 2:
The patent creates a composite structure by combining pigment particles with hydrophilic groups grafted onto their surfaces, forming a hybrid material that exhibits both the durability of pigment and the ejection stability of water-based inks
2Manufacturing precision
If recording heads with small-sized nozzles are used to improve image quality, then image precision is improved, but disarray in ejecting direction of ink droplets occurs
Solution Approach 1:
The patent modifies the surface properties of pigment particles by grafting hydrophilic groups, changing the interfacial parameters between pigment and aqueous medium to ensure stable dispersion and consistent ejection behavior from small-sized nozzles
3Speed
If penetrating agent is added to promote ink infiltration into recording media, then ink penetration is improved, but colors of ink droplets become lighter or transparent after prolonged non-use
Solution Approach 1:
The patent extracts the penetrating function from traditional penetrating agents and transfers it to the hydrophilically modified pigment surface, eliminating the need for separate penetrating agent components that cause color degradation
Solution Approach 2:
The hydrophilically modified pigment serves multiple functions simultaneously: it provides coloration, maintains stable dispersion without dispersants, and enables sufficient penetration into recording media, replacing the need for multiple separate additives
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 formulation ensures stable ejection and desired image quality by preventing ink thickening and color changes, even after prolonged non-use, while enhancing ink penetration into recording media, thus reducing image defects.
Implementation Method 1
The ink contains a high SP organic solvent and a super-penetrating agent. The content of 1,3-propanediol in the ink is from 10% to 20% by mass based on the mass of the ink.
Implementation Method 2
the ink tends to adhere to discharge rollers before the ink has penetrated into recording media when the recording media are discharged through a pair of discharge rollers (offset)
Data Source
AI summary
An ink for ink-jet recording apparatuses, includes water, a pigment dispersion, and a super-penetrating agent and a high SP organic solvent respectively having a predetermined solubility parameter (SP value). All of differences (ΔSPs) between SP values of the neighboring organic solvents are from 0.5 to 5.0 in order of SP values thereof, and the difference of SPmax−SPmin is 12 or less in which SPmax is the highest SP value of an organic solvent among organic solvents in the high SP organic solvent and SPmin is the smallest SP value of an organic solvent among organic solvents in the super-penetrating agent.