Free Radical Curable Inkjet Ink for Retroreflective Adhesion
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Solution Overview
Problem
Existing free radical curable inkjet inks used for manufacturing signs, such as traffic and guidance signs, face challenges in adhesion to retroreflective substrates under varying temperatures and have lower reflectivity compared to screen printing inks, necessitating improvements in adhesion and retroreflectivity.
Innovation Solution
Incorporating a mixture of quinacridone, diketopyrrolo pyrrole, and mixed crystal pigments with controlled particle sizes and double bond density in the ink composition, along with a specific polymerizable composition and dispersants, to enhance adhesion and retroreflectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If free radical curable inkjet inks are used for printing on retroreflective substrates, then printing flexibility and variable data capability are improved, but adhesion under temperature variations and retroreflectivity deteriorate compared to screen printing inks
Solution Approach 1:
The patent uses a composite ink formulation containing both monofunctional and polyfunctional polymerizable compounds, along with specific pigment mixtures (azo pigments combined with other pigments), to achieve both flexibility and reliable adhesion across temperature variations
Solution Approach 2:
The patent optimizes specific parameters including the functionality distribution of polymerizable compounds (monofunctional vs polyfunctional ratio), pigment composition ratios, and particle size distribution to balance printing flexibility with adhesion reliability under temperature variations
2Productivity
If free radical curable inkjet inks are used for printing on retroreflective substrates, then printing efficiency is improved, but retroreflectivity deteriorates compared to screen printing inks
Solution Approach 1:
The patent employs composite pigment systems combining azo pigments with additional pigment types, and composite polymerizable compositions with specific functionality distributions, to enhance retroreflectivity while maintaining inkjet printing efficiency
Solution Approach 2:
The patent adjusts critical parameters including pigment concentration, particle size distribution (5-20 μm range), and polymerizable compound composition to optimize the balance between printing efficiency and retroreflectivity performance
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 provides inkjet inks with improved adhesion to retroreflective substrates across temperature variations and enhanced retroreflectivity, matching or exceeding the performance of screen printing inks.
Implementation Method 1
free radical curable inkjet inks, preferably UV curable inkjet inks
Data Source
AI summary
A free radical curable inkjet ink containing a colour pigment and a polymerizable composition, wherein the colour pigment is a mixture of colour pigments including at least one colour pigment selected from a quinacridone pigment, a diketopyrrolo pyrrole pigment, and a mixed crystal thereof; wherein the average particle diameter of the colour pigment is between 80 nm and 240 nm as determined by a dynamic light scattering technique using a laser diode having an emission wavelength of 635 nm; wherein the polymerizable composition contains 95.0 to 99.0 wt% of monofunctional polymerizable compounds; wherein the monofunctional polymerizable compounds include a monomer selected from the group consisting of N-vinyl caprolactam, acryloyl morpholine, cyclic trimethylolpropane formal acrylate and vinyl methyl oxazolidinone; and wherein the polymerizable composition has a double bond density DBD of at least 5.40. An inkjet printing method with the free radical curable inkjet ink is also disclosed.