Radiation-Curable Clear Ink Gloss and Curability Trade-Off
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Solution Overview
Problem
Radiation-curable clear inks used in ink sets often result in a loss of glossiness when applied, as existing formulations with less bulky monomers fail to maintain sufficient glossy appearance.
Innovation Solution
The use of a radiation-curable ink set comprising a clear ink with a high content of Polymerizable monomer A1 or Polymerizable oligomer A2, defined by specific volume and area criteria using van-der-Waals radius, which are ejected and cured in combination with a color ink to enhance glossiness and extendability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a radiation-curable clear ink with conventional monomers is used, then curability is achieved, but glossiness is lost
Solution Approach 1:
The patent changes the physical parameters of the monomers by selecting compounds with larger molecular volumes (0.26 nm³ or more) and larger areas in the height direction (0.25 nm² or more). This parameter change in monomer size prevents excessive crosslinking density, maintaining free volume and molecular mobility necessary for glossiness while still achieving curability through radiation polymerization.
2Shape
If bulky monomers are used to maintain glossiness, then glossiness is improved, but curability may be compromised
Solution Approach 1:
The patent carefully selects monomers within a specific volume range (0.26 nm³ or more) that balances glossiness maintenance with curability. The defined geometric parameters ensure the monomers are bulky enough to maintain glossiness but not so large that they prevent effective polymerization and crosslinking upon radiation exposure.
3Ease of manufacture
If conventional clear ink formulation is used, then ease of manufacture is maintained, but extendability and abrasion resistance are insufficient
Solution Approach 1:
The patent creates a composite clear ink formulation by combining multiple polymerizable compounds with specific volume characteristics. This composite approach enhances extendability and abrasion resistance through synergistic effects of different monomer structures while maintaining formulation feasibility through well-defined selection criteria.
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 set maintains glossy appearance and improves extendability and abrasion resistance of the coating film, reducing ink smell and enhancing curability.
Implementation Method 1
a radiation-curable ink jet composition containing a polymerizable compound... a first curing step of applying radiation to the color ink attached to the recording medium... a second curing step of applying radiation to the clear ink attached to the recording medium
Data Source
AI summary
An ink set of a radiation-curable ink jet composition containing a polymerizable compound, wherein the ink set includes a color ink and a clear ink as the radiation-curable ink jet composition, the polymerizable compound contained in the clear ink contains at least one of Polymerizable monomer A1 and Polymerizable oligomer A2, Polymerizable monomer A1 having a volume of 0.26 nm3 or more and an area in the direction of the height relative to a long side of 0.25 nm2 or more that are defined by using the van-der-Waals radius, and a total content of Polymerizable monomer A1 and Polymerizable oligomer A2 contained in the clear ink is 80% by mass or more relative to a total amount of the polymerizable compound.