Ray-Curable Ink Composition for Gloss Uniformity and Recoatability
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Solution Overview
Problem
Existing inkjet printing technologies result in significant gloss differences between low and high coverage rate areas, and methods using extender pigments or gelling agents can cause ejection stability issues and surface defects.
Innovation Solution
An active ray-curable ink composition comprising a polymerizable compound, polymerization initiator, and a gelling agent with a wetting index of 40 mN/m or more, which includes fatty acid esters or amides with C12-C18 hydrocarbon chains, reduces gloss differences and enhances recoatability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If an extender pigment with relatively large particle size is used to reduce gloss difference, then the gloss difference between low and high coverage rate areas is reduced, but ejection stability degrades in high-resolution inkjet printers
Solution Approach 1:
The invention changes the particle size parameter of the extender pigment from relatively large (which causes ejection stability issues) to fine particles of 0.01 μm to 0.1 μm. This parameter change allows the pigment to effectively reduce gloss difference while maintaining ejection stability in high-resolution inkjet printing.
Solution Approach 2:
The invention uses a composite approach by combining fine extender pigment particles with specific gelling agents (fatty acid amides) in controlled amounts. This composite material system achieves both gloss reduction and ejection stability through the synergistic effect of the fine particles and the gelling agent.
2Manufacturing precision
If a gelling agent such as fatty acid amide is used to reduce gloss difference, then the gloss difference between low and high coverage rate areas is reduced, but floating of gelling agent on print surface occurs causing pinholes or repellency
Solution Approach 1:
The invention optimizes the concentration parameter of the gelling agent by using fatty acid amide at a specific range of 1 mass% to 10 mass%. This parameter optimization ensures sufficient gloss reduction while preventing excessive gelling agent that would float on the surface and cause defects.
Solution Approach 2:
The invention applies the gelling agent locally in controlled amounts rather than uniformly in excess. By localizing the gelling agent at optimal concentrations in the ink composition, it reduces gloss effectively without causing floating or surface defects.
3Ease of operation
If the wetting index of cured coating film is increased to improve recoatability, then recoatability is improved, but gloss difference reduction becomes more difficult
Solution Approach 1:
The invention uses a composite material system combining fine extender pigment (0.01-0.1 μm) with fatty acid amide gelling agent (1-10 mass%). This composite system simultaneously achieves both low gloss difference and high wetting index (40 mN/m or more) by leveraging the complementary properties of the two materials.
Solution Approach 2:
The invention optimizes multiple parameters simultaneously: extender pigment particle size (0.01-0.1 μm), gelling agent concentration (1-10 mass%), and resulting wetting index (≥40 mN/m). These parameter changes work together to achieve both gloss reduction and improved recoatability.
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 composition achieves reduced gloss variation between low and high coverage areas while maintaining excellent curability and recoatability, minimizing surface defects and ensuring stable ejection.
Implementation Method 1
an active ray-curable ink composition for inkjet printing, comprising: a polymerizable compound; a polymerization initiator
Implementation Method 2
a gelling agent, wherein a wetting index of a cured coating film to be formed by inkjet printing is 40 mN/m or more
Implementation Method 3
a wetting index of a cured coating film to be formed by inkjet printing is 40 mN/m or more
Data Source
AI summary
Provided is an active ray-curable ink composition for inkjet printing, which is capable of reducing a gloss difference between a low coverage rate area and a high coverage rate area and is excellent not only in curability but also in the recoatability when applying a varnish composition on a coating film to be obtained. An active ray-curable ink composition for inkjet printing, comprising: a polymerizable compound; a polymerization initiator; and a gelling agent, wherein a wetting index of a cured coating film to be formed by inkjet printing is 40 mN/m or more.