Polymerizable Liquid Crystal Composition Volume Shrinkage
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing image display devices with optically anisotropic layers or phase difference films suffer from suboptimal contrast due to volume shrinkage during polymerization, which disrupts the alignment state of liquid crystal compounds.
Innovation Solution
A polymerizable liquid crystal composition is developed by blending a compound represented by Formula (I) with a specific compound represented by Formula (II), where the array of aromatic and alicyclic rings is aligned similarly between the two compounds, and at least one of A5 or G3 in Formula (II) is a 1,4-cyclohexylene group, to alleviate volume shrinkage and enhance contrast.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polymerizable liquid crystal composition is used to form an optically anisotropic layer, then the device can achieve optical compensation and viewing angle expansion, but volume shrinkage during polymerization disrupts the liquid crystal alignment state and reduces image contrast
Solution Approach 1:
The patent introduces a specific compound (Formula II) as an intermediary substance between the polymerizable liquid crystal compound (Formula I) and the final cured structure. This compound has a rigid core structure with aromatic and alicyclic rings that maintains structural integrity during polymerization, acting as a mediator that prevents volume shrinkage from disrupting the liquid crystal alignment while still allowing the polymerization reaction to proceed for optical compensation functionality.
Solution Approach 2:
The patent creates a composite liquid crystal composition by blending the polymerizable liquid crystal compound (Formula I) with the specific compound (Formula II) having rigid aromatic and alicyclic ring structures. This composite material combines the polymerizable properties needed for optical compensation with the structural stability of the rigid compound, achieving both optical functionality and alignment preservation during curing.
2Manufacturing precision
If the liquid crystal compound is immobilized in a smectic phase to create an optically anisotropic layer, then phase difference control is achieved, but the polymerization process causes volume shrinkage that degrades image contrast
Solution Approach 1:
The patent modifies the chemical structure parameters of the liquid crystal composition by incorporating Compound (II) with specific rigid ring structures (aromatic and alicyclic) into the polymerizable liquid crystal Compound (I). This structural parameter change increases the overall rigidity and reduces the polymerization-induced volume shrinkage, allowing the smectic phase to be maintained with better alignment stability during curing, thus preserving image contrast while maintaining phase difference control.
3Adaptability or versatility
If a stretched birefringent film is used as an optical film, then optical compensation is achieved, but the invention seeks to replace it with a liquid crystal-based optically anisotropic layer for improved performance
Solution Approach 1:
The patent utilizes the phase transition properties of liquid crystal compounds, specifically the smectic phase, to create an optically anisotropic layer that can be cured while maintaining its liquid crystal order. The rigid compound (Formula II) stabilizes this phase transition process, ensuring that the liquid crystal molecules maintain their aligned configuration during polymerization, thereby achieving alignment stability comparable to or better than stretched birefringent films while providing the versatility of liquid crystal-based optical compensation.
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 blended composition results in improved contrast for image display devices by allowing the specific compound to intercalate between the molecules of the reverse dispersion liquid crystal compound, mitigating volume shrinkage and maintaining alignment, thereby enhancing the overall performance of the image display device.
Implementation Method 1
a polymerizable liquid crystal composition comprising: a compound represented by Formula (I); and a compound represented by Formula (II)
Data Source
AI summary
Provided is a polymerizable liquid crystal composition with which an image display device having an excellent contrast can be manufactured; and a cured product, an optical film, a polarizing plate, and an image display device. The polymerizable liquid crystal composition contains a compound represented by Formula (I). L1-SP1-D5-(A1)a1-D3-(G1)g1-D1-[Ar-D2]q1-(G2)g2-D4-(A2)a2-D6-SP2-L2 . . . (I), and a compound represented by Formula (II), L5-SP5-D9-(A5)a3-D10-(G3)g3-D11-M . . . (II).