Inkjet Recording Method Delayed UV Curing
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Solution Overview
Problem
Conventional inkjet recording methods using radiation-curable inks often result in printed materials with low surface gloss and conspicuous stripe unevenness due to immediate curing of ink droplets upon landing, which affects the shape and spreading of the droplets.
Innovation Solution
An inkjet recording method employing an ink set with cyan, magenta, and black inks containing specific polymerizable compounds and a polymerization initiator, where the inks are discharged and exposed to actinic radiation in a controlled manner using a lamp-equipped inkjet head with trailing and leading lamps to optimize curing, ensuring the outer surface of the droplets remains liquid for a longer period, promoting spreading and coalescence while preventing interior droplet interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If radiation-curable ink is discharged and immediately cured upon landing, then curability is improved, but surface gloss deteriorates and stripe unevenness becomes conspicuous
Solution Approach 1:
The patent applies preliminary action by introducing a delay between ink discharge and radiation exposure. The ink is discharged first, allowed to spread and coalesce on the recording medium, and then exposed to radiation. This timing control prevents premature curing that would otherwise inhibit droplet spreading and cause surface defects, while still ensuring complete curing afterward.
Solution Approach 2:
The patent employs periodic action through controlled timing intervals between discharge and exposure. By regulating the exposure timing to occur after a specific period following discharge, the system allows the ink to undergo natural spreading and coalescence processes before curing begins, thereby achieving both good curability and surface quality.
2Productivity
If radiation exposure intensity is increased to improve curability, then curing speed is improved, but droplet spreading is inhibited and stripe unevenness worsens
Solution Approach 1:
The patent applies preliminary action by ensuring that ink discharge and spreading occur before radiation exposure begins. The timing is controlled so that the ink completes its spreading and coalescence process on the recording medium before the radiation exposure starts, preventing premature curing that would inhibit droplet movement and cause stripe patterns.
Solution Approach 2:
The patent employs periodic action through controlled timing intervals between discharge and exposure. By regulating the exposure timing to occur after a specific period following discharge, the system allows the ink to undergo natural spreading and coalescence processes before curing begins, thereby achieving both good curability and surface quality.
3Reliability
If ink droplets are cured immediately upon landing, then curability is improved, but droplet shape is fixed prematurely causing poor spreading and coalescence
Solution Approach 1:
The patent applies preliminary action by introducing a delay between ink discharge and radiation exposure. The ink is discharged first, allowed to spread and coalesce on the recording medium, and then exposed to radiation. This timing control prevents premature curing that would otherwise inhibit droplet spreading and cause surface defects, while still ensuring complete curing afterward.
Solution Approach 2:
The patent employs periodic action through controlled timing intervals between discharge and exposure. By regulating the exposure timing to occur after a specific period following discharge, the system allows the ink to undergo natural spreading and coalescence processes before curing begins, thereby achieving both good curability and surface quality.
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 produces printed materials with high surface gloss, inconspicuous stripe unevenness, and improved curability, achieving high color saturation and image reflection density by controlling the exposure timing and intensity to prevent droplet interference and enhance the curing process.
Implementation Method 1
an ink set comprising at least a cyan ink, a magenta ink, a yellow ink, and a black ink, the inks of each color comprising a polymerizable compound and a polymerization initiator
Data Source
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AI summary
An inkjet recording method is provided in which image formation is carried out by employing an ink set, the inks of each color including a polymerizable compound and a polymerization initiator, and discharge of the inks being repeated 2 to 16 times for the same area, the method including at least (1) a step of discharging an ink via an inkjet head, (2) a step of irradiating the discharged ink with actinic radiation by exposure means having an illumination intensity of at least 50 mW/cm2 but less than 500 mW/cm2 at a time between 0 and 1.0 second after ink discharge so that the integrated exposure for a wavelength region of 240 to 400 nm is no greater than 40 mJ/cm2, and (3) a step of irradiating the discharged ink with actinic radiation by exposure means having an illumination intensity of at least 500 mW/cm2 after at least 1.0 second has passed after ink discharge so that the integrated exposure for a wavelength region of 240 to 400 nm is 20 to 250 mJ/cm2.