UV Curable Ink for Display Bezel Patterns
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Solution Overview
Problem
Conventional ultraviolet curable ink compositions for printing bezel patterns on display substrates suffer from instability at high temperatures, leading to decomposition and thickening issues due to light-induced polymerization reactions, which affect the adhesion and curing quality of the patterns.
Innovation Solution
A UV curable ink composition comprising a colorant, epoxy monomer, oxetane monomer, cationic photopolymerization initiator, and polymerization inhibitor, with a specific weight ratio of epoxy to oxetane monomer between 1:0.5 to 1:6, which provides improved thermal stability and maintains curing properties even at high temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional ultraviolet curable ink composition uses oxonium salt as photopolymerization initiator, then the composition can be cured by light irradiation, but the oxonium salt decomposes at high temperature to form Lewis acid which initiates polymerization reaction causing thickening problem
Solution Approach 1:
The patent changes the chemical parameters of the photopolymerization initiator system by replacing oxonium salt with a combination of iodonium salt and sulfonium salt. This parameter change eliminates the high-temperature decomposition issue while maintaining light-curing functionality, thereby resolving the contradiction between reaction stability and composition stability at high temperature.
Solution Approach 2:
The patent uses a composite photopolymerization initiator system comprising iodonium salt and sulfonium salt together with a photobase generator. This composite approach provides synergistic effects where the iodonium and sulfonium salts remain stable at high temperatures while still enabling efficient UV curing, thus resolving the stability contradiction.
2Duration of action of stationary object
If the ink composition is stored at high temperature for long time, then the composition remains stable, but natural curing reaction occurs causing viscosity increase or phase change to solid
Solution Approach 1:
The patent incorporates a polymerization inhibitor that preliminarily prevents natural curing reactions during storage. This inhibitor actively counteracts any spontaneous polymerization that might occur at high temperatures over time, allowing long-term storage without viscosity increase or phase change while maintaining composition stability.
3Strength
If the bezel pattern has large film thickness, then the adhesion is improved, but the taper angle increases causing short-circuit and bubble generation
Solution Approach 1:
The patent optimizes the monomer composition parameters, specifically using epoxy monomer and oxetane monomer in a weight ratio of 1:0.5 to 1:6. This parameter optimization enables the formation of thin film patterns with small taper angles that maintain good adhesion strength while preventing short-circuits and bubble generation.
Solution Approach 2:
The patent achieves different local qualities within the bezel pattern by controlling the curing characteristics. The composition allows for uniform curing throughout the thin film thickness, creating a pattern with consistent properties that simultaneously achieves small taper angle and adequate adhesion, rather than requiring thick film for adhesion.
Data Source
AI summary
The present invention relates to an ultraviolet curable ink composition including a colorant, an epoxy monomer, an oxetane monomer, a cationic photopolymerization initiator, and a polymerization inhibitor, wherein the weight ratio of epoxy monomer:oxetane monomer is 1:0.5 to 1:6, to a method for forming a bezel pattern by using the same, to a bezel pattern manufactured thereby, and to a display substrate having the same.