UV-Curable Inkjet Ink Formulation for Dispersion Stability and Surface Slip
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Solution Overview
Problem
UV-curable inkjet inks face challenges in maintaining dispersion stability and surface slipperiness during high-speed recording, as fatty acid additives can cause bleeding and reduce ink quality due to concentration issues.
Innovation Solution
An actinic radiation-curable inkjet ink formulation with 1-8wt% wax and 0.0001-0.10wt% fatty acid, using specific wax compounds like aliphatic ketones and fatty acid esters, and setting the recording medium temperature below the sol-gel phase transition temperature to prevent dot merging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the concentration of fatty acid in the ink is increased to enhance surface slipperiness, then surface slipperiness is improved, but dispersion stability is lowered causing density unevenness and ejection instability
Solution Approach 1:
The patent precisely controls the fatty acid concentration parameter within 0.0001 to 0.10 wt% to the total mass of wax, optimizing the balance between surface slipperiness and dispersion stability. This parameter optimization prevents both insufficient slipperiness and excessive fatty acid bleeding
Solution Approach 2:
The patent uses composite material formulation by combining specific wax compounds (aliphatic ketones and fatty acid esters with 12 or more carbon atoms) with controlled amounts of fatty acid. This composite approach enhances surface slipperiness while maintaining dispersion stability through the synergistic effect of the material composition
2Ease of operation
If the concentration of fatty acid in the ink is increased to enhance surface slipperiness, then surface slipperiness is improved, but bleeding of fatty acid on the surface occurs
Solution Approach 1:
The patent optimizes the fatty acid concentration parameter to 0.0001-0.10 wt% relative to wax mass, which is sufficient to provide surface slipperiness but low enough to prevent bleeding. This precise parameter control resolves the contradiction between slipperiness enhancement and bleeding prevention
Solution Approach 2:
The patent uses wax compounds (aliphatic ketones and fatty acid esters) as a base structure that provides the desired surface properties, with minimal fatty acid addition. The wax structure serves as a stable framework that prevents fatty acid migration to the surface
3Productivity
If high-speed recording is performed to increase productivity, then recording speed is improved, but neighboring dots combine with each other lowering image quality
Solution Approach 1:
The patent utilizes the sol-gel phase transition of the UV-curable ink formulation. The ink transitions from a mobile liquid state during ejection to a gelled state upon landing on the recording medium, providing immediate pinning of dots. This phase transition enables high-speed recording by preventing dot combination even when dots are deposited in rapid succession
Solution Approach 2:
The patent incorporates wax compounds and fatty acid in predetermined amounts to pre-establish the pinning properties of the ink formulation. This preliminary preparation ensures that the ink has sufficient surface slipperiness and rapid gelling characteristics before the recording process begins, enabling high-speed operation without dot combination
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 achieves stable dispersion and surface slipperiness without bleeding, enhancing image quality and preventing dot merging during high-speed printing.
Implementation Method 1
it has been studied, for example, to add a gelling agent (hereinafter, also referred to as 'wax') to the ink to allow the ink to undergo sol-gel phase transition depending on temperature
Implementation Method 2
UV-curable inkjet methods are known in which droplets of UV-curable ink are landed on a recording medium and then cured by irradiation with ultraviolet rays to form an image
Data Source
Figure 1A~1B
Figure 2
AI summary
The purpose of the present invention is to provide: an active ray-curable inkjet ink which has good dispersion stability during storage, good surface smoothness when ejected on a recording medium, and does not undergo the bleeding of a fatty acid onto the surface of the ink; and an image formation method using the active ray-curable inkjet ink. The purpose can be achieved by an active ray-curable inkjet ink which comprises: a photopolymerizable compound; at least one wax in the total mass of 1 to 8 mass % relative to the whole mass of the ink; and a fatty acid in the total mass of 0.0001 to 0.10 mass% relative to the whole mass of the wax.