Ink Set for Soft Packaging Films Suppressing Bleeding and Cracking
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Solution Overview
Problem
Ink jet recording methods face challenges with bleeding and cracking when forming images on soft packaging films using a layered ink structure, due to differences in shrinkage ratios between the lower and upper layers, which are influenced by the amount of solvent in each layer.
Innovation Solution
An ink jet recording method involving the formation of a first ink layer with a specific water-soluble organic solvent content and solid content ratio, followed by a drying step to evaporate 80% or more of the water, and a second ink layer formed on top with a controlled solvent content ratio, ensuring a favorable balance to minimize bleeding and cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the lower layer ink is dried to reduce bleeding, then bleeding is suppressed, but cracks and peeling occur in the obtained image
Solution Approach 1:
The patent changes the chemical composition parameters of the ink, specifically setting the solid content concentration to 5-20 mass% and the glass transition temperature to -50℃ to -20℃. These parameter changes allow the ink to achieve both bleeding suppression and crack prevention by controlling the drying behavior and flexibility of the dried ink layer.
Solution Approach 2:
The patent uses a composite ink formulation combining multiple components: water-soluble organic solvents (glycol, glycerol), solid content (resin and pigment), and specific additives. This composite material approach creates an ink that balances drying properties with flexibility, preventing both bleeding and cracking.
2Strength
If the shrinkage ratio of the lower layer and upper layer are adjusted to reduce cracks, then cracking is suppressed, but the composition control becomes complex
Solution Approach 1:
The patent simplifies the complex composition control by establishing specific parameter ranges: solid content at 5-20 mass%, glass transition temperature at -50℃ to -20℃, and defined ratios of water-soluble organic solvents. These standardized parameters make the ink formulation easier to control while achieving uniform shrinkage behavior.
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 method effectively suppresses bleeding and cracking in the final image, ensuring stable and high-quality printing on soft packaging films by balancing the solvent content and shrinkage ratios between layers.
Implementation Method 1
a first drying step of evaporating 80% by mass or more of water contained in the first ink composition in the first ink layer
Implementation Method 2
a second drying step of evaporating a volatile component on the recording medium after the step of forming a second ink layer
Data Source
AI summary
An ink jet recording method includes forming a first ink layer by ejecting a first ink composition including water, a water-soluble organic solvent, and a solid content including at least a coloring material on a recording medium; a first drying step of evaporating 80% by mass or more of water from the first ink composition in the first ink layer; forming a second ink layer by ejecting a second ink composition including water, a water-soluble organic solvent, and a solid content including at least a coloring material on the first ink layer; and a second drying step of evaporating a volatile component of the recording medium after forming the second ink layer, in which, assuming r1 is “water-soluble organic solvent content/solid content” of the first ink composition and r2 is “water-soluble organic solvent content/solid content” of the second ink composition”, “r2/r1” is 2 or less.