Asymmetric Polymerizable Liquid Crystal Compound for Film Durability
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Solution Overview
Problem
The solubility and durability of optically anisotropic films formed using polymerizable liquid crystal compounds are compromised due to variations in polymerization conditions and the type of polymerizable compound used, leading to issues with birefringence changes under high temperature and humidity exposure.
Innovation Solution
A polymerizable liquid crystal compound with an asymmetric structure, featuring a sterically hindered group in the aromatic ring and differing C log P values for the groups extending in the long-axis direction, improves solubility and durability by inhibiting moisture absorption and enhancing molecular packing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polymerizable liquid crystal compound with conventional structure is used, then the optically anisotropic film can be formed, but the solubility is deteriorated and durability is compromised due to birefringence changes under high temperature and humidity
Solution Approach 1:
The patent applies asymmetry by introducing a sterically hindered group at the para position of the aromatic ring in the liquid crystal compound structure. This asymmetric substitution creates different spatial environments for the polymerizable groups, improving molecular packing and solubility while maintaining the optically anisotropic properties necessary for film formation and durability
Solution Approach 2:
The patent applies local quality by specifically modifying the aromatic ring structure with a sterically hindered group at the para position, while keeping other parts of the molecule intact. This localized structural modification targets the solubility and durability issues without affecting the overall liquid crystal properties and optical performance of the compound
2Ease of manufacture
If the structure of liquid crystal compound is modified to improve solubility, then solubility becomes good, but the durability and birefringence stability under high temperature and humidity may be compromised
Solution Approach 1:
The asymmetric substitution with a sterically hindered group improves solubility by preventing excessive molecular aggregation, while the rigid aromatic core and liquid crystalogenic groups maintain the molecular anisotropy necessary for stable birefringence. The asymmetric structure promotes uniform molecular orientation in the film, preserving optical stability
Solution Approach 2:
The patent changes the structural parameters of the liquid crystal compound by introducing the sterically hindered group, which modifies the molecular volume, shape, and intermolecular interaction parameters. These parameter changes improve solubility while the liquid crystal phase behavior and optical properties are maintained through careful selection of the core structure
3Reliability
If conventional polymerizable liquid crystal compounds are used, then the optically anisotropic film can be formed, but moisture absorption occurs leading to durability issues
Solution Approach 1:
The patent converts the potential harm of moisture absorption by designing a molecular structure where the sterically hindered group creates a hydrophobic environment around the polymerizable groups. This structural feature effectively repels moisture while the polymer network formed after curing provides additional barrier properties, transforming the challenge of moisture resistance into a design advantage
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 proposed compound achieves excellent solubility and durability for optically anisotropic films, maintaining birefringence stability even under high temperature and humidity conditions, as evidenced by improved retardation values and resistance to environmental changes.
Implementation Method 1
the solubility and durability of optically anisotropic films formed using polymerizable liquid crystal compounds are compromised due to variations in polymerization conditions and the type of polymerizable compound used, leading to issues with birefringence changes under high temperature and humidity exposure
Data Source
AI summary
An object of the present invention is to provide a polymerizable liquid crystal compound having excellent solubility, which is used for the formation of an optically anisotropic film having excellent durability, a method for producing the same, a polymerizable liquid crystal composition, an optically anisotropic film, an optical film, a polarizing plate, and an image display device. The polymerizable liquid crystal compound of the embodiment of the present invention is a polymerizable liquid crystal compound represented by Formula (1), L1-SP1-A1-D3-G1-D1-Ar-D2-G2-D4-A2-SP2-L2 . . . (1) in Formula (1), the ClogP value of the group represented by L1-SP1-A1-D3-G1-D1 and the ClogP value of the group represented by L2-SP2-A2-D4-G2-D2 are different from each other, and at least one of the ClogP values is 3.3 or more.