Inkjet Ink Supply Control for Thermal Polymerization Stability
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Solution Overview
Problem
Existing inkjet recording devices using radical curable UV inks for solder masks face issues with thermal polymerization due to radical species, leading to ink thickening and polymerization reactions, especially under high application volumes and high productivity requirements, which compromise coating film durability and solder heat resistance.
Innovation Solution
The method involves controlling the ink supply to a first sub-tank such that the amount of newly supplied ink exceeds the amount remaining, minimizing ink residence time to maintain ink stability and prevent thermal polymerization, using a radical polymerizable ink containing a thermosetting component.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the amount of thermosetting component is increased to improve coating film durability, then coating film durability is improved, but ink viscosity increases requiring higher heating temperature
Solution Approach 1:
The patent controls the residence time of ink in the heating section as a critical parameter. By limiting how long ink stays in the heated zone, the system can process high-viscosity ink containing thermosetting components without allowing excessive thermal polymerization to occur, thus maintaining ink stability while achieving the required heating effect for proper viscosity adjustment
2Ease of operation
If the ink is heated at higher temperature to adjust viscosity, then viscosity is adjusted to optimum range, but thermal polymerization risk increases
Solution Approach 1:
The patent employs a heating section with controlled length that allows ink to pass through quickly at elevated temperature for viscosity adjustment, then immediately enters a cooling section. This rapid transit prevents prolonged exposure to high temperatures that would cause thermal polymerization, thus achieving viscosity control while maintaining ink stability
Solution Approach 2:
The system dynamically controls temperature and residence time parameters. By adjusting the heating section length and ink flow rate, the patent optimizes the balance between achieving proper viscosity through heating and preventing excessive thermal polymerization that would compromise ink stability
3Reliability
If ink degassing is performed under high temperature conditions, then dispensing reliability is improved, but thermal polymerization is promoted
Solution Approach 1:
The patent performs degassing in advance within the ink supply tank before ink enters the heating and dispensing sections. By removing dissolved gases early at lower temperatures, the system eliminates cavitation risks later during high-temperature dispensing without exposing ink to prolonged high-temperature conditions that would cause polymerization
Solution Approach 2:
The patent divides the thermal processing into distinct segments: a heating section for viscosity adjustment and a separate cooling section for temperature reduction. This segmentation allows controlled heating for the necessary duration to achieve proper ink flow properties, followed by rapid cooling to prevent thermal polymerization before ink reaches the dispensing head
4Productivity
If high application volume and high productivity are achieved, then productivity is improved, but ink residence time increases causing polymerization
Solution Approach 1:
The patent employs a circulation system that dynamically adjusts ink flow through the heating and cooling sections. By maintaining continuous circulation at optimized flow rates, the system achieves high application volumes and productivity while ensuring ink residence time remains sufficiently short to prevent thermal polymerization during repeated circulation cycles
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 approach ensures stable ink discharge over time without thickening or polymerization, enhancing coating film durability and solder heat resistance by suppressing thermal decomposition and optimizing photo-curing and post-bake thermal curing efficiency.
Implementation Method 1
a heating device for heating at least a flow path of the ink in the first sub-tank
Implementation Method 2
a degassing device connected to the first sub-tank to degas the ink supplied from the first sub-tank
Implementation Method 3
the ink is a radical polymerizable ink containing a thermosetting component
Data Source
Figure 1A~1B
Figure 2
Figure 3
AI summary
An inkjet recording method for ejecting ink from an inkjet head 24a to record an image comprises a main tank 51 that serves as an ink supply source, a first sub-tank 241 that is connected to the main tank 51 and to which ink is supplied, a degassing device that is connected to the first sub-tank 241 and degasses the ink supplied from the first sub-tank 241, a second sub-tank 245 that supplies the ink degassed by the degassing device to an inkjet head 24a and controls a negative pressure applied to the inkjet head 24a, and a heating device 270 that heats at least a flow path of the ink in the first sub-tank 241. The method further comprises a control unit 40 that feeds the ink so that the amount of ink freshly supplied from the main tank 51 to the first sub-tank 241 is greater than the amount of ink remaining inside the first sub-tank 241. The ink is a radical polymerizable ink containing a thermosetting component.