Hybrid UV-IR Curing of Photocurable Resin for Scratch Resistance
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Solution Overview
Problem
Current photocurable resin compositions face challenges in achieving efficient curing with ultraviolet light, particularly in reducing irradiation time, increasing cross-linking density, and preventing curling without using special additives, while also being cost-effective and effective under various irradiation conditions.
Innovation Solution
The method involves applying infrared irradiation with a wavelength range of 1-6 microns to a photocurable resin composition to enhance the decomposition efficiency of photo polymerization initiators, followed by ultraviolet irradiation for a shorter duration than typically required, and optionally including post-infrared irradiation to reduce curing time and stress relaxation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If ultraviolet light irradiation is used to cure photocurable resin composition, then curing reaction is initiated, but irradiation time is long and curing efficiency is low
Solution Approach 1:
The patent applies preliminary infrared irradiation to heat the photocurable resin composition before ultraviolet curing. This preliminary heating action activates the photo polymerization initiators in advance, creating a more favorable condition for subsequent UV curing and significantly reducing the required UV irradiation time.
Solution Approach 2:
The patent changes the temperature parameter of the photocurable resin composition by applying infrared irradiation. This temperature increase enhances the decomposition efficiency of photo polymerization initiators and accelerates the polymerization reaction rate, thereby improving overall curing efficiency.
2Productivity
If photo polymerization initiators are increased to promote curing reaction, then curing rate improves, but process cost increases
Solution Approach 1:
The patent changes the temperature parameter through infrared irradiation to enhance the decomposition efficiency of existing photo polymerization initiators. This approach achieves higher curing rates without increasing the amount of initiators, thereby avoiding increased material costs.
3Stability of the object's composition
If metal oxide ultra fine particles are added to prevent curling, then curling is reduced, but cross-linking density and hardness characteristics are lowered
Solution Approach 1:
The patent applies preliminary infrared irradiation to heat and pre-activate the resin system before UV curing. This preliminary action enables achieving both curling prevention and high hardness characteristics without requiring metal oxide additives that would compromise cross-linking density.
4Reliability
If ultraviolet light irradiation is applied for long duration, then complete curing is achieved, but energy consumption increases and yellowing occurs
Solution Approach 1:
The patent applies preliminary infrared irradiation to heat the resin and activate initiators before UV curing. This preliminary action creates optimal conditions for rapid and complete curing under reduced UV exposure, minimizing energy consumption and preventing yellowing while ensuring complete curing.
Solution Approach 2:
The patent changes the temperature parameter through infrared heating to accelerate the polymerization reaction kinetics. This enables achieving complete curing with shorter UV irradiation time, thereby reducing energy consumption and minimizing photodegradation that causes yellowing.
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 significantly reduces curing time, enhances scratch resistance, and decreases the amount of photo polymerization initiators needed, while minimizing curling and maintaining high cross-linking density without the use of special additives, thus improving the overall curing process efficiency and cost-effectiveness.
Implementation Method 1
applying infrared irradiation having a wavelength range between 1 and 6 microns to a photocurable resin composition including at least one photo polymerization initiator, from which volatile components have been removed by a heating process in advance
Implementation Method 2
from which volatile components have been removed by a heating process in advance
Implementation Method 3
The photo polymerization initiators become activated through absorption of light (in particular, UV) to thereby initiate such reactions as cleavage reaction, hydrogen abstraction and electron transfer so that there are produced such materials as radical molecules and hydrogen ions that initiate the polymerization reaction
Implementation Method 4
The photo polymerization initiators become activated through absorption of light (in particular, UV)
Implementation Method 5
applying a post infrared irradiation within one hour after the application of the ultraviolet ray irradiation so as to accelerate a curing reaction or to apply a stress relaxation effect
Data Source
Figure 1
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Figure 3A~3B
AI summary
A technology for curing a photocurable resin composition by ultraviolet ray/infrared ray hybrid irradiation is provided. An infrared ray irradiation is applied at least one of before or after the application of ultraviolet ray irradiation to a photocurable resin composition, from which volatile components have been removed by a heating process, to have the photocurable resin composition cured. It becomes possible to relax the ultraviolet ray irradiation conditions for photo curing by applying an infrared ray irradiation as compared with the case in which the infrared ray irradiation is not applied, and, in particular, the scratch resistance characteristics of a cured film are significantly enhanced. Moreover, because of a combination of ultraviolet ray irradiation and infrared ray irradiation, the curing time period of a cured film can be reduced and/or stress relaxation effects can be produced . Besides, it becomes possible to control the reflectance of a cured film by varying an irradiation amount of infrared ray.