Curing Indicator Printing Coating for UV Curing Reliability
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Solution Overview
Problem
Existing radiation-cured coating systems face challenges with incomplete curing, leading to migration of coating components through substrates, particularly in rapid printing processes, which results in printing waste and quality issues.
Innovation Solution
A coating composition comprising reactive compounds, radical photoinitiators, amine compounds, and non-photobleaching colored dyes, which reacts with free radicals to indicate sufficient curing, allowing for reliable human perception of curing completion without the need for additional analytical equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If maximum lamp output is used to guarantee curing of the coating film, then curing reliability is improved, but coating quality deteriorates due to yellowing and other printing quality issues
Solution Approach 1:
The patent employs a color-changing indicator system where a dye embedded in the coating composition changes color based on the curing state. During UV irradiation, the dye transitions from an initial color to a different color when sufficient curing is achieved, providing visual feedback without requiring maximum lamp output that causes yellowing. This allows optimization of curing parameters to avoid harmful effects while ensuring adequate curing.
2Measurement precision
If complicated spectroscopic based measuring methods are used to determine curing, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent replaces complex spectroscopic measurement systems with a simple visual color-change indicator system. The dye in the coating composition directly indicates curing state through color change observable by human eye or simple sensors, eliminating the need for sophisticated infrared or near-infrared spectroscopic equipment while maintaining sufficient measurement precision for production control.
3Ease of operation
If photobleaching dyes are used to indicate curing, then ease of operation is improved, but reliability deteriorates because they do not provide reliable indication of actual curing
Solution Approach 1:
The patent uses a specific dye as an intermediary that responds to UV irradiation in a controlled manner. The dye is selected and formulated to change color at curing levels that ensure complete polymerization, serving as a reliable mediator between the UV curing process and visual indication. The dye's color change is correlated with actual curing chemistry, providing both ease of operation and reliability.
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 proposed solution provides an economical and reliable method for ensuring sufficient hardening of radiation-curing printing coatings, reducing waste and quality issues by allowing for real-time visual confirmation of curing completion.
Implementation Method 1
the radical photoinitiator (R) contains species (of the so called type II photoinitiator) that are able to interact with amino groups in such a way that the generation of free radicals is activated when exposed to electromagnetic radiation
Implementation Method 2
non-photobleaching colored dye (C) which is able to react with free radicals under bleaching of its color
Implementation Method 3
from 40 - 97 wt.% of reactive compound (M) containing at least one free radically polymerizable double bond
Data Source
AI summary
The invention relates to a coating composition having an amine value of 6 – 90 mg KOH comprising:i) from 40 – 97 wt.% of reactive compound (M) containing at least one free radically polymerizable double bond,ii) from 2.5 – 20 wt.% of radical photoinitiator (R), iii) amine compound (D) containing at least one amino group and iv) non-photobleaching colored dye (C) which is able to react with freeradicals under bleaching of its color, wherein the wt.% is relative to the total weight of the composition,(M) is different from (R); (D) is different from (R); and (C) is different from (R) and (M); andthe radical photoinitiator (R) contains species that are able to interact with amino groups in such a way that the generation of free radicals is activated when exposed to electromagnetic radiation.