Ink Formulation Ejection Stability and Image Glossiness
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Solution Overview
Problem
Inkjet recording processes using inks with pigments and water-soluble polyurethane polymers face issues with low glossiness, ejection stability, and optical density, particularly when thermal energy is used to eject the ink, as the polymer components tend to stick to the recording head, causing misalignment and reduced image quality.
Innovation Solution
The ink formulation includes a pigment, a water-soluble polyurethane polymer, a polyethylene oxide alkyl ether with 12 or more carbon atoms, and an ethylene oxide-propylene oxide (EO-PO) type surfactant, where the surfactant is adsorbed on the polyethylene oxide alkyl ether, reducing hydrophobic interaction with the recording head and enhancing the ink's surface activity, thereby improving ejection stability, glossiness, and optical density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If an ink containing a water-soluble polyurethane polymer is used to improve glossiness, then the glossiness of the image is improved, but the ejection stability of the ink deteriorates due to polymer sticking to the recording head
Solution Approach 1:
The patent introduces a surfactant as an intermediary substance between the polyurethane polymer and the recording head. This surfactant adsorbs onto the polymer chains, creating a protective layer that prevents direct contact and sticking between the polymer and the recording head surface, thereby maintaining ejection stability while preserving the glossiness enhancement effect of the polymer
Solution Approach 2:
The patent modifies the chemical parameters of the ink formulation by adjusting the type, concentration, and molecular weight of the surfactant added to the ink containing water-soluble polyurethane polymer. These parameter changes optimize the balance between the polymer's glossiness-enhancing properties and its tendency to stick to the recording head, achieving stable ejection while maintaining image quality
2Reliability
If an EO-PO type surfactant is added to improve ejection stability, then the ejection stability is improved, but the glossiness and optical density of the image deteriorate
Solution Approach 1:
The patent optimizes the concentration and molecular weight parameters of the EO-PO type surfactant to achieve the minimum effective amount needed for ejection stability without excessive surfactant that would interfere with pigment adhesion and image glossiness. By precisely controlling this parameter, the surfactant provides sufficient stabilization while minimizing negative impact on image quality
Solution Approach 2:
The patent creates a composite ink system combining water-soluble polyurethane polymer, EO-PO type surfactant, and pigment in specific proportions. This composite formulation allows the surfactant to fulfill its ejection stability function while the polymer maintains glossiness and the pigment provides optical density, with each component synergistically contributing to the overall performance
3Reliability
If the content of EO-PO type surfactant is increased to improve ejection stability, then the ejection stability is improved, but the optical density of the resulting image deteriorates
Solution Approach 1:
The patent determines the optimal concentration parameter of EO-PO type surfactant that provides sufficient ejection stability while minimizing interference with pigment deposition and optical density. By identifying this optimal point, the formulation achieves stable ink ejection without excessive surfactant that would reduce image optical density
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 combination of components in the ink significantly improves ejection stability, glossiness, and optical density of the resulting image, ensuring high-quality image production by inhibiting face wetting and promoting pigment surface retention, while maintaining the ink's compatibility and fixing time.
Implementation Method 1
an ethylene oxide-propylene oxide (EO-PO) type surfactant, where the surfactant is adsorbed on the polyethylene oxide alkyl ether
Implementation Method 2
an ink jet recording process in which an ink is ejected from a recording head by the action of thermal energy
Data Source
AI summary
The invention provides an ink for use in an ink jet recording process in which an ink is ejected from a recording head by the action of thermal energy, the ink comprising a pigment, a water-soluble polyurethane polymer, a compound represented by a general formula (1) having a weight-average molecular weight of 1,000 or more and 8,500 or less, and a polyethylene oxide alkyl ether, the alkyl group of which has 12 or more carbon atoms,wherein, based on the total mass of the ink, the content (mass %) of the compound represented by the general formula (1) is 0.4 times or more and 10.0 times or less in terms of mass ratio with respect to the content (mass %) of the polyethylene oxide alkyl ether.