Photocurable Composition for Liquid Crystal Displays
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Solution Overview
Problem
Conventional photocurable compositions using photobase generators face issues with high costs due to excessive photobase generator requirements, limited applicability for heat-sensitive members, and uncertain storage stability, particularly in the context of liquid crystal display devices.
Innovation Solution
A photocurable composition comprising an epoxy compound, an acrylic ester compound, an isocyanate compound, a photobase generator, and a compound with a thiol group, with specific mass ratios and structural characteristics, optimizing the reactivity and storage stability by adjusting the amounts of these components to reduce the photobase generator requirement and enhance curing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a photobase generator is used as a reaction initiator to avoid inhibition by oxygen and moisture, then the polymerization reaction can proceed without inhibition, but the cost increases due to excessive photobase generator requirements
Solution Approach 1:
The patent changes the concentration parameter of the photobase generator from excessive amounts in conventional compositions to a controlled range of 0.1-5 mass%, and adjusts the mass ratio of epoxy compound to photobase generator to 100:0.1-5, thereby reducing the quantity of photobase generator while maintaining reliable polymerization reaction
Solution Approach 2:
The patent creates a composite photocurable composition by combining epoxy compound, acrylic ester compound, isocyanate compound, photobase generator, and compound with thiol group in specific ratios, where the synergistic interaction of multiple components enables effective curing with reduced photobase generator content
2Temperature
If a photobase generator is used to achieve curing at room temperature or low heating temperature, then heat-sensitive members can be processed, but storage stability becomes uncertain
Solution Approach 1:
The patent optimizes the mass ratio of epoxy compound to photobase generator within 100:0.1-5 and controls the content of compound with thiol group at 5-50 mass% based on total composition, which stabilizes the composition during storage while maintaining the ability to cure at room temperature or low heating temperature
Solution Approach 2:
The patent uses a photobase generator that can be easily decomposed by light irradiation after serving its function of initiating polymerization, allowing the system to maintain stability during storage (when no light is present) and activate only when needed, effectively separating the storage state from the curing state
3Quantity of substance
If the mass ratio of epoxy compound to photobase generator is optimized to reduce photobase generator content, then cost decreases and storage stability improves, but curing reactivity may be affected
Solution Approach 1:
The patent introduces compound with thiol group as an intermediary substance that mediates between the photobase generator and epoxy compound, enhancing the efficiency of the polymerization initiation process and enabling effective curing even with reduced photobase generator content
Solution Approach 2:
The patent formulates a composite system where acrylic ester compound and isocyanate compound work synergistically with the epoxy compound and photobase generator, creating multiple reaction pathways that maintain high curing reactivity despite lower photobase generator concentration
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 composition achieves excellent curing reactivity and high storage stability, suitable for liquid crystal display devices with improved optical properties and reduced photobase generator usage, enabling effective adhesion and delayed curability.
Implementation Method 1
a photobase generator, which is a base in which the polymerization reaction is not inhibited by oxygen or moisture, and the shrinkage of the cured product is small, and the reaction initiator does not cause problems such as corrosion or yellowing by irradiation with light
Implementation Method 2
a photocurable composition that cures the members from a liquid to a solid by irradiation with light
Data Source
Figure 1~2
AI summary
There is provided a photocurable composition including Component (A): epoxy compound, Component (B): acrylic ester compound, Component (C): isocyanate compound, Component (D): photobase generator, and Component (E): compound having a thiol group, in which Component (A) has two or more epoxy groups in one molecule, Component (B) has two or more acryloyl groups in one molecule, Component (C) has two or more isocyanate groups in one molecule, and Component (E) has two or more thiol groups in one molecule, and a ratio of a total mass of Component (A), Component (B), Component (C), and Component (D) to a mass of Component (E) is (Component (A) + Component (B) + Component (C) + Component (D)): Component (E) = 74: 26 to 20: 80.