Aqueous Ink Post-Treatment Liquid Solubility Parameter Control
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Solution Overview
Problem
Existing image forming technologies face challenges in achieving glossiness when a post-treatment liquid is applied to an unfixed image formed by aqueous ink, as the liquid mixes with the ink, preventing the formation of a uniform coating film and resulting in poor glossiness.
Innovation Solution
An image forming set comprising an aqueous ink with a colorant, water-soluble organic solvent, and water, and a post-treatment liquid with a urethane resin or acrylic resin, where the solubility parameter of the post-treatment liquid's mixed solution is lower than that of the ink's mixed solution by 1.5 (cal/cm3)1/2 or greater, ensuring the post-treatment liquid forms a uniform coating without mixing with the ink.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the post-treatment liquid is applied onto a surface of an image formed by ejecting the aqueous ink in the unfixed state, then high-speed printing can be realized, but the post-treatment liquid is mixed into the image, preventing the formation of a uniform coating film and resulting in poor glossiness
Solution Approach 1:
The patent changes the solubility parameter of the post-treatment liquid by selecting specific water-soluble organic solvents with carefully controlled ratios. The mixed solution contains a water-soluble organic solvent with a solubility parameter of 15.0 to 25.0 (cal/cm³)¹/² in an amount of 5 wt% to 50 wt%, creating a solubility parameter difference of 1.5 (cal/cm³)¹/² or more with the aqueous ink. This parameter adjustment prevents mixing while enabling uniform coating film formation on unfixed images, achieving both high-speed printing and good glossiness.
2Ease of operation
If the solubility parameter difference between the post-treatment liquid and aqueous ink is small, then the post-treatment liquid can be applied, but the liquid mixes with the ink, leading to poor glossiness
Solution Approach 1:
The patent establishes a specific solubility parameter range (15.0 to 25.0 (cal/cm³)¹/²) for the water-soluble organic solvent and controls its concentration (5 wt% to 50 wt%) in the post-treatment liquid. This creates an optimal solubility parameter difference of 1.5 (cal/cm³)¹/² or more with the aqueous ink, preventing mixing while maintaining ease of application and achieving good glossiness.
Solution Approach 2:
The post-treatment liquid uses a composite solvent system combining water and specific water-soluble organic solvents (such as polyhydric alcohols, carboxylic acid esters, or amides) in controlled proportions. This composite material approach allows tuning the overall solubility parameter to achieve the required difference with the ink, preventing mixing while maintaining applicability and glossiness.
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
This solution effectively imparts glossiness to the image by forming a uniform coating film on the image, even when applied to an unfixed state, while maintaining the ink's properties and improving abrasion resistance.
Implementation Method 1
A solubility parameter of a mixed solution of the water-soluble organic solvent and the water in the post-treatment liquid is lower than a solubility parameter of a mixed solution of the water-soluble organic solvent and the water in the aqueous ink by 1.5 (cal/cm3)1/2 or greater
Data Source
AI summary
To provide an image forming set including: an aqueous ink including a colorant, a water-soluble organic solvent, and water; and a post-treatment liquid including a water-soluble organic solvent, water, and at least one of a urethane resin and an acrylic resin, wherein a solubility parameter of a mixed solution of the water-soluble organic solvent and the water in the post-treatment liquid is lower than a solubility parameter of a mixed solution of the water-soluble organic solvent and the water in the aqueous ink by 1.5 (cal/cm3)1/2 or greater.