UV Curing Heat-Sensitive Substrates with Active Cooling
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Solution Overview
Problem
Current printing methods for absorbent article components face challenges in curing inks on heat-sensitive substrates at high speeds without damaging the substrates, particularly when using ultraviolet curable inks, as high radiation intensity can destroy the substrate during the curing process.
Innovation Solution
A printing system that includes a cooling apparatus adjacent to the substrate to manage heat energy while curing ultraviolet curable inks, ensuring the substrate temperature remains below its onset temperature, thereby preventing damage and allowing for efficient curing at high speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high radiation intensity is used to cure ultraviolet curable inks at high speeds, then curing efficiency is improved, but the substrate is damaged due to excessive heat
Solution Approach 1:
A cooling apparatus is introduced as an intermediary between the radiation source and the substrate during the curing process. This cooling apparatus (comprising cooling rollers and/or air knives) actively removes heat from the substrate, mediating the harmful thermal effect of ultraviolet radiation while allowing the curing reaction to proceed at high speeds without damaging the heat-sensitive substrate
2Loss of time
If high radiation intensity is applied to cure ink quickly, then curing time is reduced, but heat energy accumulates and destroys the substrate
Solution Approach 1:
The cooling apparatus operates continuously or periodically during the curing process to intermittently or continuously remove heat from the substrate. This periodic cooling action prevents heat accumulation even when high radiation intensity is applied, allowing rapid curing while maintaining substrate temperature below the onset temperature
Solution Approach 2:
The harmful heat energy generated by ultraviolet radiation during high-speed curing is converted into a controllable parameter by introducing active cooling. The cooling apparatus transforms the potentially destructive thermal effect into a manageable condition, allowing the system to exploit high radiation intensity for rapid curing while using the cooling mechanism to prevent substrate damage
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 system effectively cures ultraviolet curable inks on heat-sensitive substrates without damaging them, enabling high-speed processing while maintaining substrate integrity.
Implementation Method 1
a cooling apparatus adjacent the advancing substrate and configured to remove heat energy from the substrate during the curing process so as to maintain the maximum temperature of the substrate in the illumination zone below the onset temperature
Implementation Method 2
energy curable inks that are cured by chemical reactions. Examples of energy curable inks may include ultraviolet curable inks. Once energy curable ink is deposited in a liquid state on a substrate, the ink may be cured and solidified by subjecting the ink to a radiation source, such as ultraviolet light
Implementation Method 3
During the curing process, the radiation source imparts energy to the ink. The energy imparted to the ink from the radiation source is proportional to the intensity of the radiation directed at the ink and the time during which ink is subjected to the radiation
Data Source
Figure 1A
Figure 1B
Figure 1C
AI summary
The present disclosure relates to a methodfor printing and curing energy curable inks (304) printed on a substrate (200) having an onset temperature Tonset(C°). The printing systems (300) may include a printing station (302) and a light source (308). During operation, the printing station (302) deposits energy curable ink (304) onto a first surface (202) of the substrate (200) to define a printed region (400), and the light source (308) directs ultraviolet light (310) onto the first surface (202) of the substrate (200) to define an illumination zone (312) on the first surface (202) of the substrate (200). The substrate (200) is advanced in a machine direction (MD) to advance the printed region (400) through the illumination zone (312) to cure the energy curable ink (304). While the printed region (400) advances through the illumination zone (312), the ultraviolet light (310) heats the substrate (200) from an initial temperature Tin(C°) entering the illumination zone (312) to a maximum temperature Tmax(C°), wherein Tmax(C°) ≤ Tonset(C°).