Ink Set With Polymer Emulsion Binder for Rubbing Resistance
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Solution Overview
Problem
Existing inkjet technologies face limitations in commercial printing due to issues with ink fixability, water resistance, and surface gloss, particularly when using aqueous pigment inks on common printing papers, which result in unsatisfactory rubbing resistance and image quality during high-speed recording.
Innovation Solution
An ink set comprising a pigment, polymer particles with an ethylene oxide chain, and a water-soluble polymerizable compound capable of being polymerized by active energy rays, along with a coagulant treatment liquid, which coagulates ingredients to enhance image immobilization and strength, improving rubbing resistance and glossiness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If aqueous pigment ink is used on common printing paper, then cost is reduced and adaptability is improved, but rubbing resistance and water resistance deteriorate
Solution Approach 1:
A polymer emulsion serving as a binder is introduced as an intermediary substance between the aqueous pigment ink and common printing paper. This binder adheres to both the ink particles and the paper surface, enabling effective fixation without requiring specialized inkjet papers. The binder acts as a mediating layer that bridges the incompatibility between aqueous-based ink and conventional paper, thereby improving rubbing resistance while maintaining adaptability to common printing papers.
Solution Approach 2:
The ink composition is formulated as a composite material system comprising pigment particles, polymer emulsion binder, and aqueous solvent in specific proportions. This composite structure allows the ink to function effectively on common printing paper by combining the adhesive properties of the polymer emulsion with the pigment's coloration capabilities, overcoming the limitation of using simple aqueous pigment suspensions that lack sufficient binding strength.
2Ease of manufacture
If aqueous pigment ink is used on common printing paper, then production cost is reduced, but image strength and fixability deteriorate
Solution Approach 1:
The polymer emulsion binder serves as a mediating substance that strengthens the bond between pigment particles and paper fibers. By incorporating this binder into the aqueous pigment ink formulation, the ink gains sufficient adhesion and image strength to be used on cost-effective common printing papers, thereby reducing overall production costs while maintaining acceptable image strength for commercial printing applications.
Solution Approach 2:
The ink formulation parameters are optimized by adjusting the concentration and molecular weight of the polymer emulsion binder, as well as the pigment-to-binder ratio. These parameter changes enable the ink to achieve adequate image strength on common printing paper without requiring expensive specialized substrates, thus reducing production costs while maintaining functional performance.
3Productivity
If high-speed recording is performed, then productivity is improved, but sufficient thermal fixing cannot be achieved and fixability deteriorates
Solution Approach 1:
The fixing mechanism is transitioned from a thermal-based system to a chemical-based system. Instead of relying on heat to evaporate the aqueous solvent and fix the ink (which is time-consuming and insufficient at high speeds), the formulation utilizes polymer emulsion that provides rapid adhesion through chemical bonding and coagulation upon contact with the paper. This substitution enables effective fixing at high recording speeds without requiring prolonged thermal treatment.
Solution Approach 2:
The ink formulation is modified by selecting polymer emulsions with lower glass transition temperatures and optimized molecular weights that enable rapid coagulation and fixation at ambient or mildly elevated temperatures. This parameter optimization allows the ink to achieve sufficient fixability through chemical adhesion rather than thermal evaporation, thereby supporting high-speed recording operations while maintaining reliable fixability.
4Reliability
If polymer with lowered softening temperature is used to improve fixability at high speed, then fixability is improved, but adhesion phenomenon (blocking) occurs in high-temperature environment
Solution Approach 1:
The polymer emulsion parameters are precisely controlled by selecting polymers with specific glass transition temperatures (Tg) and molecular weights. The Tg is optimized to be low enough to enable rapid coagulation and fixation at ambient or mildly elevated temperatures during high-speed recording, but not so low that the polymer becomes overly soft and adhesive in high-temperature storage environments. This parameter optimization balances fixability improvement with prevention of blocking phenomena.
Solution Approach 2:
The polymer emulsion formulation is designed with local quality considerations by incorporating specific functional groups and crosslinking agents that enhance adhesion during the fixation process but provide thermal stability during storage. The localized chemical modifications enable the polymer to exhibit different properties under different conditions: high adhesion during fixation and reduced adhesion during storage, thereby resolving the contradiction between improved fixability and prevention of blocking.
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 set achieves excellent rubbing resistance and uniform image surfaces with improved glossiness, suitable for high-speed recording on coated papers, while preventing intermixing of ink droplets and enhancing image printing properties.
Implementation Method 1
a water-soluble polymerizable compound having an ethylene oxide chain and capable of being polymerized by active energy rays
Implementation Method 2
a treating liquid containing a coagulant that coagulates ingredients in the ink composition
Data Source
AI summary
The present invention provides an ink set including: an ink composition including a pigment, polymer particles having an ethylene oxide chain in a side chain of the polymer, and a water-soluble polymerizable compound that has an ethylene oxide chain and that is polymerized by active energy rays; and a treating liquid including an aggregating agent that aggregates ingredients in the ink composition.