Ink Set Discharge Stability via Reaction Liquid Extraction
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Solution Overview
Problem
Conventional aqueous inks for ink-jet printing face issues with discharge stability and film formation on non-absorbing or low-absorbing substrates, leading to beading, unevenness, and poor adherence due to the presence of film-forming aids in the ink, which can cause nozzle clogging and inadequate film strength.
Innovation Solution
Incorporating a glycol ether-based solvent and/or glycol ether acetate-based solvent in the reaction liquid instead of the aqueous ink, with an emulsion glass transition temperature set at 50° C. or higher, improves discharge stability and film properties such as rubbing resistance and adherence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If film-forming aids (glycol ether-based solvent, glycol ether acetate-based solvent) are contained in the aqueous ink, then film formability and rubbing resistance are improved, but nozzle clogging occurs and discharge stability deteriorates
Solution Approach 1:
The patent extracts the film-forming aid (glycol ether-based solvent and/or glycol ether acetate-based solvent) from the aqueous ink formulation and places it only in the reaction liquid. This separation eliminates the harmful effect of film-forming aids causing nozzle clogging while preserving their beneficial film-forming properties in the reaction liquid where they contribute to coating film formation without compromising discharge stability.
2Ease of manufacture
If emulsion glass transition temperature is set low for easy film formation, then film formation at ambient temperature is facilitated, but nozzle clogging occurs due to emulsion solidification
Solution Approach 1:
The patent changes the glass transition temperature parameter of the emulsion to 50°C or higher, which prevents emulsion solidification at nozzle temperatures and ensures stable discharge. Simultaneously, the reaction liquid containing glycol ether-based solvent and/or glycol ether acetate-based solvent enables the emulsion to form films with adequate adherence and rubbing resistance despite the higher glass transition temperature.
3Adaptability or versatility
If conventional aqueous ink is used on non-absorbing or low-absorbing substrates, then substrate compatibility is achieved, but drying speed decreases and beading occurs
Solution Approach 1:
The patent segments the ink system into two separate components: aqueous ink for substrate coverage and reaction liquid for film formation. The reaction liquid, containing aggregating agent and film-forming aids, is discharged simultaneously or sequentially to promote rapid drying and prevent beading on non-absorbing or low-absorbing substrates while maintaining substrate compatibility through the aqueous ink component.
4Productivity
If aqueous ink is discharged with short interval on non-absorbing substrate, then printing efficiency is improved, but inter-color bleeding occurs due to insufficient drying
Solution Approach 1:
The patent applies preliminary action by including the reaction liquid with aggregating agent and film-forming aids that promote rapid drying and film formation. This preliminary preparation in the reaction liquid formulation enables the ink to dry quickly even when discharged with short intervals, preventing inter-color bleeding and maintaining image quality while allowing high printing efficiency.
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 proposed ink set achieves enhanced discharge stability and improved coated film properties, including better rubbing resistance and adherence, while preventing nozzle clogging and ensuring sufficient film strength.
Implementation Method 1
an emulsion contained in an aqueous ink becomes easier to form a film by drying at an ambient temperature
Implementation Method 2
By containing the film-forming aid of the aqueous ink, an emulsion contained in an image formed on the surface of a recording medium sufficiently sticks thereto to form a film
Implementation Method 3
an image is formed by volatilization of a solvent such as water and an organic solvent contained in the aqueous ink, on the surface of a recording medium
Data Source
AI summary
There is provided an ink set for ink-jet printing comprising an aqueous ink and a reaction liquid, wherein the aqueous ink contains an emulsion, a surfactant, an organic solvent, a pigment, and water, the reaction liquid contains an aggregating agent, 1,2-alkanediol, a glycol ether-based solvent and/or a glycol ether acetate-based solvent, and water, and the emulsion has a glass transition temperature of 50° C. or higher. The ink set for ink-jet printing is provided with an aqueous ink excellent in the discharge stability, and can form an image excellent in coated film properties such as the rubbing resistance and the adherence.