UV-Curable Inkjet Ink for Polypropylene Adhesion
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Solution Overview
Problem
Conventional inkjet ink compositions face challenges in achieving high surface gloss, high image density, and excellent substrate adhesion, particularly on polypropylene, while minimizing the feeling of grain in low-density images and ensuring antiblocking properties.
Innovation Solution
The inkjet ink composition comprises a radically polymerizable monomer blend with specific components, including N-vinyllactam, cyclic trimethylolpropane formal acrylate, phenoxyethyl acrylate, and a difunctional/trifunctional (meth)acrylate, along with a bisacylphosphine polymerization initiator, optimized for a surface tension range of 34.0 to 40.0 mN/m, which promotes excellent curing properties and substrate interaction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional inkjet ink compositions are used, then printing can be performed on various recording media, but the surface gloss and image density are insufficient
Solution Approach 1:
The patent optimizes the surface tension parameter of the ink composition to 34.0-40.0 mN/m and carefully controls the ratios of polymerizable compounds (monofunctional: 40-70 wt%, difunctional: 5-30 wt%, polyfunctional: 5-20 wt%). These parameter changes enable the ink to achieve high surface gloss and image density while maintaining consistent print quality across different recording media.
Solution Approach 2:
The patent employs a composite ink composition system combining multiple types of polymerizable compounds (N-vinyllactam, cyclic trimethylolpropane formal acrylate, phenoxyethyl acrylate, and difunctional/polyfunctional (meth)acrylates) with a bisacylphosphine polymerization initiator. This composite formulation achieves superior surface gloss and image density that cannot be obtained with single-component inks.
2Manufacturing precision
If the ink composition is optimized for high image density, then print quality improves, but graininess increases in low-density images
Solution Approach 1:
The patent uses a combination of monofunctional, difunctional, and polyfunctional polymerizable compounds that provide different local properties: monofunctional compounds contribute to flow and coverage, while difunctional and polyfunctional compounds provide crosslinking density. This local quality differentiation allows high image density without excessive graininess in low-density areas.
Solution Approach 2:
The patent controls the surface tension within 34.0-40.0 mN/m and adjusts the functional group ratios to optimize the balance between image density and grain reduction. This parameter optimization ensures that ink distributes evenly without forming excessive aggregates that cause graininess.
3Strength
If the ink composition uses high surface tension to improve adhesion, then substrate adhesion improves, but surface gloss decreases
Solution Approach 1:
The patent optimizes surface tension to a specific range (34.0-40.0 mN/m) that balances adhesion and gloss. This intermediate surface tension value allows sufficient substrate wetting and adhesion while preventing excessive spreading that would reduce surface gloss and create graininess.
Solution Approach 2:
The composite formulation with multiple polymerizable compounds provides synergistic effects: the combination of different functional groups creates a cured film structure that maintains both strong substrate adhesion and high surface gloss, resolving the traditional trade-off between these properties.
4Ease of manufacture
If conventional ink formulations are used, then printing process is simple, but antiblocking properties are insufficient
Solution Approach 1:
The patent adjusts the surface tension parameter to 34.0-40.0 mN/m and controls the polymerizable compound composition, which results in cured ink films with optimal surface energy. This parameter optimization provides excellent antiblocking properties while maintaining a relatively simple printing process that does not require additional treatment steps.
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 composition results in high surface gloss, high image density, reduced graininess, enhanced substrate adhesion, and improved antiblocking properties, particularly on polypropylene, ensuring superior print quality and durability.
Implementation Method 1
a curing step of curing the discharged ink composition by irradiating with UV using a light-emitting diode that emits UV having an emission peak wavelength in the range of 300 to 400 nm
Implementation Method 2
irradiating with UV using a light-emitting diode that emits UV having an emission peak wavelength in the range of 300 to 400 nm so that the maximum illumination intensity on the recording medium surface is 600 to 1,600 mW/cm2
Data Source
AI summary
An inkjet ink composition is provided that includes (Component A) a radically polymerizable monomer including at least Components A-1 to A-4, (Component A-1) an N-vinyllactam, (Component A-2) a compound represented by Formula (1), (Component A-3) a compound represented by Formula (2) or Formula (3), and (Component A-4) a di- or higher-functional (meth)acrylate compound and, as (Component B) a polymerization initiator, (Component B-1) a bisacylphosphine compound, the total content of Components A-1 to A-3 being 65 to 90 wt%, the content of Component A-4 being 1 to 9 wt%, and the surface tension at 25°C being 34.0 to 40.0 mN/m.