UV-Curable Ink Jet Layering for Glossy Coatings
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Solution Overview
Problem
Existing ink jet methods using ultraviolet curable ink sets struggle to achieve glossiness in clear ink coatings, particularly when layered over color ink coatings, which can result in reduced appearance quality in printed materials like signage.
Innovation Solution
The method involves a two-layer radiation-curable ink jet process where a first ink composition with a high monofunctional monomer content is cured and then cooled, followed by a second ink composition application and curing, using a specific polymerizable compound and photopolymerization initiator formulation to enhance glossiness and scratch resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If clear ink is applied over color ink to form a multilayer coating, then the coating provides protection and potential glossiness, but the glossiness is reduced and appearance quality deteriorates
Solution Approach 1:
The first ink composition is cured by UV irradiation before applying the second clear ink composition. This preliminary curing action creates a stable, non-reactive surface that prevents interaction between the two ink layers during subsequent curing, thereby maintaining glossiness while providing protective functionality.
Solution Approach 2:
The patent changes the chemical composition parameters of the ink system by using specific polymerizable compounds (acrylates, vinyl esters, vinyl ethers) and photopolymerization initiators with defined wavelength ranges (300-400nm UV). These parameter changes enable controlled curing that preserves surface gloss while achieving adequate coating protection.
2Stability of the object's composition
If UV irradiation is applied to cure the first ink composition, then the ink is cured and provides structural integrity, but the recording medium becomes hot which can affect subsequent ink application
Solution Approach 1:
The first ink composition is fully cured by UV irradiation before the second clear ink composition is applied. This preliminary curing action ensures complete polymerization and structural stability of the first layer, preventing thermal degradation or incomplete curing that would occur if layers were applied simultaneously or in reverse sequence.
Solution Approach 2:
The process maintains continuous useful action by immediately applying the second clear ink composition after the first layer cures, without unnecessary delays. This continuous workflow ensures the recording medium cools sufficiently while maintaining production efficiency and preventing overheating that would occur with extended UV exposure or waiting periods.
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 approach improves the glossiness and scratch resistance of the printed matter by preventing interaction between the first and second ink compositions during curing, resulting in a higher-quality finish while maintaining the image integrity of the first ink composition.
Implementation Method 1
irradiating the first ink composition adhered to the recording medium with radioactive rays
Implementation Method 2
a cooling device for cooling the recording medium
Data Source
AI summary
An ink jet method records a radiation-curable ink composition containing a polymerizable compound. The radiation-curable ink composition includes a first ink composition and a second ink composition. The ink jet method includes a first discharging step of discharging the first ink composition with an ink jet head to adhere the composition to a recording medium, a first curing step of irradiating the first ink composition adhered to the recording medium with radioactive rays, a cooling step of cooling the recording medium, a second discharging step of discharging the second ink composition with the ink jet head to adhere the composition to the cooled recording medium at least in a part of the region where the first ink composition adhered; and a second curing step of irradiating the second ink composition adhered to the recording medium with radioactive rays.