Radiation-Curable Clear Ink Composition for Gloss and Scratch Resistance
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Solution Overview
Problem
The use of specific radiation-curable clear inks in ink sets results in a loss of glossy appearance after application, particularly when a clear ink with a large amount of low bulky monomer is used.
Innovation Solution
Incorporating a predetermined amount of a bulky monomer A with a volume of 260 angstrom 3< or more and an area of 25 angstrom 2< or more into the clear ink, along with a weighted average glass transition temperature of 48°C or more for the polymerizable compounds, to enhance scratch resistance and maintain glossy appearance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a clear ink with a large amount of low bulky monomer is used, then the ink is easy to discharge and apply, but the glossy appearance is lost after application
Solution Approach 1:
The patent changes the physical parameters of the monomers by selecting bulky monomers with specific volume (260 ų or more) and area (25 Ų or more) characteristics. This parameter change allows the monomer to provide both ease of discharge and maintain glossy appearance by creating a coating film with appropriate molecular packing and surface properties.
Solution Approach 2:
The patent uses a composite approach by combining bulky monomer A with other polymerizable compounds (monofunctional and multifunctional monomers) in specific ratios. This composite material strategy allows the clear ink to achieve both easy dischargeability and glossy appearance maintenance through synergistic effects of different monomer components.
2Strength
If the weighted average glass transition temperature of polymerizable compounds is increased to 48°C or more, then scratch resistance is enhanced, but the ink may become harder to discharge
Solution Approach 1:
The patent carefully controls the glass transition temperature parameter of the polymerizable compounds to be 48°C or more, which enhances scratch resistance while maintaining dischargeability. This is achieved by selecting monomers with appropriate Tg values and combining them in specific ratios, balancing the rigidity needed for scratch resistance with the fluidity needed for easy discharge.
3Shape
If bulky monomer A with specific volume and area is incorporated into clear ink, then glossy appearance is maintained, but the formulation complexity increases
Solution Approach 1:
The patent defines specific parameter thresholds for bulky monomer A (volume ≥260 ų, area ≥25 Ų) to systematically identify suitable monomers. This parameter-based approach simplifies the formulation process by providing clear selection criteria, reducing the complexity of finding appropriate monomers while ensuring glossy appearance maintenance.
Solution Approach 2:
The patent applies local quality by focusing on the specific structural characteristics of monomer A (bulkiness, volume, area) that locally affect the coating film properties. By targeting these specific molecular properties, the formulation achieves glossy appearance without requiring complex overall formulation adjustments.
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 solution effectively suppresses a reduction in gloss and enhances scratch resistance while maintaining a glossy appearance, improving the overall quality of the coating film.
Implementation Method 1
an ink set of radiation-curable ink jet compositions each including a polymerizable compound component... a first curing step of irradiating the color ink adhered to the recording medium with radioactive rays... a second curing step of irradiating the clear ink adhere to the recording medium with radioactive rays
Data Source
Figure 1
AI summary
Provided is an ink set of radiation-curable ink jet compositions each including a polymerizable compound component. The ink set includes a color ink and a clear ink as the radiation-curable ink jet compositions. The polymerizable compound component contained in the clear ink includes a monomer A having a volume of 260 angstrom3 or more and an area of 25 angstrom2 or more in the height direction with respect to a long side defined by a van-der-Waals radius, and the content of the monomer A contained in the clear ink is 80 mass% or more based on the total amount of the polymerizable compound component.